Journal of the History of Biology, Vol. 3, No. 2

Dollo on Dollo's Law: Irreversibilityand the Status of EvolutionaryLaws STEPHEN JAY GOULD Museum of Comparative Zoology, Harvard University Cambridge, Massachusetts

I. DOLLO'S FORMULATION OF DOLLO'S LAW Irr,versibilit6: je suis bien tranquille sur l'avenir et l'utilite de cette notion: seulement, pour la soutenir ou pour la combattre, il faut bien la comprendre, ce qui n'arrive pas toujours!

L. Dollo in letter to T. Edinger, July 9, 1927 Othenio Abel launched Palaeobiologica with a wish that the ideas of Louis Dollo might flourish and bring prosperity to the new journal.1 Palaeobiologica did not survive the war; Dollo's name lives as a masthead to the law of irreversibility, but his forgotten work presents this notion in a fashion altogether different from the formulations of our textbooks. Abel's journal may have met a kinder fate. Dollo's law, moreover, has fallen into disrepute along with the entire enterprise that sought to abstract historical laws from the phenomena of phylogeny. I find this unfortunate for two reasons: 1. Apart from any judgment on the merit of Dollo's law, I regret this foreclosure of discussion since the debate on historical laws illuminates so many issues in the philosophy of biology (reductionism, the nature of history). 2. Irreversibility, in its most important sense, is a notion quite different from the standard set of such 'laws"-those named for Cope, Williston, etc. By an ironic twist, as we shall see, "Dollo's law" emerges as a particularized statement of the 1. Othenio Abel, "Die Festgabe der 'Palaeobiologica,'" (1928), 1-8.

Palaeobiologica,

Journal of the History of Biology, vol. 3, no. 2 (Fall 1970), pp. 189-212.

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general reason for our rejection of an approach to phylogeny based on a search for such historical laws. Louis Dollo (1857-1931) was a much misunderstood man. Born and educated in Lille, he began a lifetime career at the Brussels Museum in 1882 after a brief stint as a mining engineer. His open support of Germany during the First World War precluded any future popularity with his Belgian colleagues; yet with a stubbornness that he attributed to his Breton ancestry, he remained at his post as a virtual recluse. While he maintained a few loyal friends and a uniquely high status in the paleontological community of Europe, his seclusion and avoidance of the politics of scientific societies fostered his reputation as a quietly dedicated, coldly dispassionate scientist. All that he hid from his colleagues he disclosed in the extraordinary correspondence with Dr. Tilly Edinger, found after the latter's death in 1967; here, interspersed with Wagnerian quotations of death and yearning, we find the words of a lonely and tormented idealist. As he concealed his feelings by force of personality, so also did he withhold his ideas by habits of writing. He wrote neither text nor review article, and we paleontologists have forgotten that his pale'ontologie ethologique was the source for a type of research that we all pursue today-the study of adaptation in relationship to environment. He wrote no discursive prose, no elaboration of general ideas, but listed his contentions only as sets of summary propositions. The quoted source for all his evolutionary theorizing is a two page resume in the Proces-Vebaux of 1893 for the geological society of Belgium (translated as an appendix to this article); rarely did he elaborate any further in his later works. He wrote to Edinger of his views on scientific prose (September 21, 1929): "Dollo's style, a telegraphic style-difficult to read . . . Yes, but clear, brief, precise-that is my purpose! The consequence of a strong mathematical educationl An original memoir is not a storyl" These examples of his published statements on irreversibility are typical: A Dollo epitome. 2 Nautilus does not yet have fins; Octopus has them no longer. From this point of view the series ends where it begins. But there is nothing contrary to irreversibility in this. After all, Octopus has not turned into a nautiloid. 2. 1912, p. 117. A chronological bibliography of Dollo's work on irreversibility is presented at the close of this article. Citations herein are by date and refer to these works.

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Dollo on Dollo's Law The didactic Dollo demonstrating that unrolled ammonoids have not reverted to the ancestral straight nautiloid :3 None of them has become the ancestral Orthoceras again . neither wholly, nor partially: neither in the initial chamber, nor in the sutures, nor in the aperture, nor in the siphon, nor in the ornament, nor in the process of uncoiling. Magnificent examples of irreversibility! Yet from the totality of such apothegms emerges a very definite and consistent view of the natural world, of evolution and of paleontology. Dollo's thoughts on irreversibility flow naturally, almost inevitably, from this conceptual framework. Divorced from it, his phrases are easily misinterpreted. When understood but depicted without the theoretical underpinning that Dollo provided, irreversibility appears as an isolated curiosity, and one is left wondering why Dollo invoked it so often and with so much ardor. Dollo on the natural world: Dollo was educated in the mechanistic tradition that dominated late nineteenth-century science. His strong reductionist bias taught him that the goal of biology was to abstract from the organic world a set of governing laws patterned after the deterministic system then prevalent in physics. This belief not only prescribed a general methodology (to search for laws), but also led Dollo to an important particular conclusion: the necessary association of a cause and its effect meant that a given environment would always elicit the same type of adaptive morphological response. When L. Plate criticized the law of irreversibility on the grounds that "the organic world cannot be ordered according to absolutely inviolable laws," Dollo replied:4 I cannot declare myself to be in agreement with him, because if there are natural laws, they must be as constant for organisms as for the inorganic world. It seems only that they are more complicated and, as a consequence, more difficult to discover and to define for organisms. To admit the contrary would be to return to vitalism. And after both he and Tilly Edinger had written independently to each other of the garden at Stratford-On-Avon where the flowers mentioned in Shakespeare's plays are grown (letter of June 4, 1927), he commented: 3. 1922, p. 219. 4. 1922,p. 223.

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Shakespeare Garden: yes the coincidence is curious! But there is something even more curious! In a purely mechanical explanation of the universe, this coincidence was already scheduled, billions of years ago in the primitive nebula of Kant, to occur on May 31, 19271 Otherwise, where would it have come from? For there is no chance in nature! The famous French mathematician Laplace (the successor of Kant in natural cosmogeny) said that "we call chance the phenomena of which we are, for the moment, incapable of discovering the causes." And another explanation of the universe? I do not know of any. Dollo on the nature of evolution: Three of Dollo's evolutionary views are particularly relevant to his notion of irreversibility: 1. Evolution is discontinuous. De Vries, in fact, credited Dollo as the first to have stated this postulate on the basis of modern evolutionary ideas.5 2. In the course of evolution, different organs often evolve independently of each other and at different rates., In a paper on lungfish evolution Dollo emphasized this "overlapping (chevauchement) of specializations" and cited as an example:7 "Hipparion has passed the Equus stage in its dentition; Equus has passed the Hipparion stage in limb development." Although he returned infrequently to this principle in his published work, he considered it of great importance, for he listed it along with irreversibility, discontinuity, and limitation among "my laws of evolution." 8 3. Evolution is limited. Dollo used this phrase in two senses. First, evolution is limited because a highly specialized organism cannot adjust to a rapidly altered environment and becomes extinct-an acceptable statement for modern evolutionists. Of the specialized turtle, Lytoloma, Dollo wrote:9 All is sacrificed to an overly precise purpose. They have lost the necessary plasticity to continue to evolve . . . A new proof that evolution is limited, since it is the organisms whose structure responds most exactly to a determined adaptation which disappear without descendants . . . We still have 5. 1912, p. 140. 6. Paleontologists today refer to this phenomenon as "mosaic evolution." 7. 1895, p. 88. 8. Letter to Tilly Edinger, November 26, 1927. It is often mentioned in subsequent letters. 9. 1903, pp. 25-26.

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Dollo on Dollo's Law turtles, crocodiles, lacertilians and even rhynchocephalians, but we have no more dinosaurs, ichthyosaurs, plesiosaurs, mosasaurs, or pterosaurs. Second, evolution is limited because each lineage has a definite life cycle based on an inherently finite capacity for phyletic variation.10

Dollo wrote in his short paper on the laws of evolution:'1 "Is evolution limited or indefinite? Does each organism carry within itself a boundless power of metamorphosis or must it necessarily become extinct after having run through a determined cycle? . . . All organisms must necessarily become extinct after having run through a determined cycle which may, however, be extremely long." Later, Dollo supported the view of his "eminent maltre," A. Giard, that 'living fossils" such as Lingula and the opossum have stopped evolving "because they have no more dispensable potential for modification and they would die rather than change." 12 Dollo on the nature of paleontology: Dollo believed that "phylogeny will always be the supreme goal of Paleontology," 13 but he deplored the speculative approach, so characteristic of late nineteenth-century paleontology, that built lineages from morphological series without regard to the adaptive significance of observed stages. A truly evolutionary paleontology could only result from the synthesis of two approaches:14 "Phylogenetic paleontology which studies inherited characters in order to establish filiation and ethological paleontology which studies adaptive characters in order to recognize convergences." Failure to recognize convergence was the prime error of the speculative school.'5 Only an ethological approach could correct such errors. 10. Such a belief is usually associated with various shades of vitalism, but this was certainly not the case with Dollo. Lamarck was accused of vitalism for his belief in the sentiment intdrieur, but the existence of such fluxes and flows was central to his view of the physical world and carried no implication of a special status for life. Likewise, Dollo believed that phyletic life cycle was as natural an idea as individual life cycle. As a convinced mechanist, Dollo was a foe of vitalism in any of its forms. Never could any internal force work to produce or even to preserve an inadaptive configuration. An "old" species dies because it cannot evolve the required adaptation to a changing environment. 11. 1893., p. 165. 12. 1905a, p. 131. 13. 1909a, p. 386. 14. Ibid., p. 387. 15. To emphasize this point, Dollo often and proudly cited his demonstration (1895) that the gephyrocercal tail of modern lungfishes is a secondary adaptation to benthic life and not a sign of primitive status. At that

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Basic environments are few; stages in a lineage many. At some point in the history of most lineages, a derived form will return to the environment of a distant ancestor. Since this environment requires a definite and predictable functional adaptation (a consequence of Dollo's determinism), convergence to the external form of the ancestor must occur. If paleontology can succeed in its "supreme goal," these convergences must be recognizable; the derived form must be distinguishable from its distant ancestor of the same environment. It is at this point that the concept of irreversibility enters Dollo's system, for irreversibility provides the guarantee that

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convergent forms can be distinguished and placed in their proper positions in an evolutionary sequence. Irreversibility is no isolated curiosity in Dollo's thought, but an essential step in his argument that paleontology is a worthwhile endeavor. time, many paleontologists wanted to view living lungfish as survivors of a primitive stock that had given rise to terrestrial vertebrates.

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Dollo on Dollo's Law The definition of irreversibility is given in this context in Dollo's work on secondary quadrupedalism in dinosaurs.16 This article begins: In all studies of adaptation, we must distinguish with care whether we are dealing with a primary or a secondary adaptation. In other terms, whether the organism is evolving to

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16. 1905b.

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satisfy certain determined conditions of existence for the first time, or, having once left these conditions of existence, it is retuming to them, after having adopted, for a more or less long time, another way of life. He then defines irreversibility as follows: An organism never returns exactly to a former state, even if it finds itself placed in conditions of existence identical to those in which it has previously lived. But by virtue of the indestructibility of the past . . . it always keeps some trace of the intermediate stages through which it has passed.'7 Though Dollo is often done the injustice of being lumped with the orthogeneticists, it is clear that he never proposed irreversibility for all evolutionary events. Quite the contrary, for he only invoked the concept when he needed to show that complete structural reversal did not accompany reversal in function or environmental preference (see Fig. 1 for an example illustrated by Dollo). He applied irreversibility only to complicated morphologies: "Functional or physiological reversal occurs; structural or morphological reversal does not occur." 18 Within this theme that complicated structures are not reevolved, Dollo mixed two statements of rather different status. 1. The entire organism never returns to a former state: If organisms could reacquire an ancestral form exactly, only an extremely complete fossil record of gradual change would permit the attainment of Dollo's "supreme goal"-the establishment of phylogeny. For, to demonstrate such a reversal, one would have to be able to link the second appearance through all intermediate stages to the form most different from beginning and end points (to a terrestrial mammal for the whale that became a fish). Given the imperfection of the geological record'9 and, especially, Dollo's belief in the discontinuity of evolution, such a linking could not be imagined. This first statement is not an empirical postulate (if such reversals occur, we cannot discern them), but an a priori methodological assumption that preserves the possibility of establishing phylogenies. Speaking of sawfish, Dollo writes:20 Sawfish have not become sharks again. Otherwise, how would we be able to know that they had once been depressi17. 18. 19. 20.

Ibid., 1903, 1895, 1922,

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p. 443. p. 32. p. 88. p. 218.

Dollo on Dollo's Law form rays in a benthic life intercalated between the primary and secondary nectic life. We know it because, in reality, sawfish are not sharks, but squaliform rays. He called the notion of complete reversibility a "postulate which, unless we possessed an absolutely complete paleontological series (which we are far from having), would destroy aUlpossibility of arriving at phylogenies, the supreme goal of morpholOg-ft 21 ogy."2 2. A complex part of an organism never returns exactly to a former state. This is a testable statement about convergent structures.22 Dollo claimed that he based his phylogenies on this second statement of irreversibility, but this was rarely true. He based them on careful morphological comparisons of all parts, not only upon the "indestructible" signs of ancestry preserved in the convergent structure; a phylogeny can be established even if one part reverts exactly to a former state. For example, he states that modern pycnodont fishes are either deep-bodied and adapted to a planktonic life or fusiform and adapted to nektonic life.23 Assuming that the ultimate ancestors of pycnodonts were fusiform, which of the two modem groups represents the primitive state? Not the fusiform species, says Dollo, because deepbodied pycnodonts appear first in the geologic record (chronology) and maintain primitive squamation, teeth, and vertebral column (morphology). The following phylogeny is thus established without irreversibility fusiform pycnodonts

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Now we can discern an example of irreversibility because the 21. 1907, p. 12. 22. It is a testable statement only if "good faith" is maintained in interpreting the qualifying term "complex." This term gives the statement an "open texture" that allows an unscrupulous supporter to exclude any event from its domain by claiming that the event was not sufficiently complex. See Friedrich Waismann, "Verifiability," in A. Flew (ed.), Language and Logic (Oxford: Basil Blackwell, 1951). Flew claims that we lose interest in such a hypothesis because it has suffered "death by a thousand qualifications" (A. Flew, New Essays in Philosophical Theology [London SCM Press], pp. 96-97). With a reasonable limit upon the term "complex", Dollo's statement is testable; if "complex" is used to exclude any possible counterinstance, the statement becomes unfalsifiable. 23. 1912, pp. 108-109.

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neural spines of secondarily fusiform pycnodonts still possess the reinforcement layers needed by their planktonic ancestors to support the great body height. Likewise, this statement cannot be used, as Dollo claimed,24 to determine the direction of evolution. Chronology and not the obviously reptilian nature of fish-like Ichthyosaurus teaches us that the lineage of crossopterygian fish-terrestrial reptileichthyosaur did not proceed in reverse order. Were these stages known only as an isolated structural sequence of modern forms, we could not establish direction without some additional postulates on the nature of evolutionary change.25 Although we reject the more elaborate claims made by Dollo for this second statement of irreversibility, its importance is by no means diminished. As an affirmation that secondary convergences can be recognized morphologically by their preservation of some trace of an intermediate stage,26 this statement of irreversibility is central to Dollo's scientific study of adaptation. While the status of each of these two statements of irreversibility is different-one statement is an unprovable but necessary assumption, the other a testable proposition-Dollo correctly offered the same justification for both. The unifying theme is complexity. Precise reversal does not occur because this would require that the organism retrace, exactly and in the same order, an extremely large number of steps. Since the components of an organism can evolve independently of one another (his belief in mosaic evolution), the reacquisition of a complex structure will demand nearly as many independent steps as there are components-it cannot be claimed that the parts of a structure are complex effects of a single cause.27 The theory of probability would not permit the second occurrence of such a large series of independent events. Thus Dollo insisted, though the opposite claim is still being made,28 that irreversibility is not a mere empirical generalization from the facts of phylogeny. Such a charge was insulting to a man who prided himself on the deductive powers he had acquired through mathematical study. 24. 1922, p. 224, for example. 25. See 1905b, p. 442. 26. Osborn referred to irreversibility as the "law of alternate adaptation." H. F. Osborn, The Origin and Evolution of Life (New York: Charles Scribner's Sons, 1917). 27. Pleiotropy, and Gregor Mendel for that matter, were unknown when Dollo formulated his views. 28. Branislav Petronievics, "Sur la loi de l'6volution irreversible," Sci. Prog., 13 (1918), 406-419; 0. H. Schindewolf, Grundfragen der Paldontologie (Stuttgart: Schweizbart, 1950), p. 209.

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Dollo on Dollo's Law The irreversibility of evolution is not simply an empirical law resting on facts of observation, as many have believed. It has deeper causes which lead it, in the last analysis, to a question of probabilities as with other natural laws. In effect, evolution is a summation of perfectly determined individual variations in a perfectly determined order. In order for it to be reversible, we would have to admit the intervention of causes exactly inverse to those which gave rise to the individual variations which were the source of the first transformation and also to their fixation in an exactly inverse order-a circumstance so complex that we cannot imagine that it has ever occurred. Otherwise, we might as well maintain that by throwing into the air the characters necessary for printing the Iliad, the poem would be completely composed by the simple fall of these little metallic blocks.29 Dollo never stated it quite so explicitly, but I think it fair to infer that he based the application of irreversibility upon the position of a phenomenon in a complexity continuum. An identical organism, he stated, is less likely to be re-evolved than an identical organ; a simple function can be reversed, a complex structure cannot.30 When a phenomenon reaches a sufficient degree of complexity, requiring a sufficient number of independent steps for its realization, repetition becomes "absolutely unimaginable-there are too many other possibilities, the probability is nil."3' In his work on lungfish, he wrote: "Notice that we are not speaking here of an isolated character but of an entire series of characters . . . Now it is, above all, in its action upon highly multiple elements, that we can affirm with certainty that evolution is not reversible." 32 As with all continua, there will be problems with borderline cases, and Dollo cited as examples of irreversibility some phenomena that most of us would class in the simple, reversible range.33 I would put in this category of misplaced borderline cases the claims that bone derived from cartilage cannot revert to cartilage, and that secondarily marginal trilobite eyes will 29. 1913, p. 59. 30. 1900, p. 14; 1903, p. 32. 31. 1922, p. 215. 32. 1895, p. 122. 33. It is, of course, well known that simple structures with a simple genetic base can be reconstituted when lost. See Bjorn Kurten, "Return of a lost structure in the evolution of the felid dentition," Soc. Scient. Fenn. Comment. Biol., 26 (1963), 3-11; G. Hemmingsmoen, "Zig-zag evolution." Norsk Geol. Tids., 44 (1964), 341-352.

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not assume their original position relative to the glabella.34 These examples are unfortunate, for they lead to the implication that Dollo had in mind more than just complexity as a justification for irreversibility. Irreversibility, as most of the vernacular words we borrow for scientific jargon, is not blessed with the unambiguity of a single meaning. As we have been using the term, irreversibility is a function of the complexity of a series of independent events. There is, however, another sense of irreversibility exemplified by a notice I once found tacked to a coffee machine: "Irreversibility: you can't get your dime back, by pouring the coffee back into the machine." The dime is lost not because many independent events are involved in its return (flipping 100 heads in a row with an honest coin), but because the machine is programmed in such a way that once the dime is committed, it can't be reclaimed without breaking the rules (jimmying the lock, bribing the collector). The irreversibilities proposed by various orthogenetic theories fall in this second category. If it were true that successive members of phyletic series always increased in size, then a reverse trend would be excluded not because smaller size is a complex genetic change but because evolution would then be programmed to prevent this tendency as long as the rules were followed. Did Dollo ever speak of an irreversibility in this second sense? In particular, were certain trends in evolution programmed in such a way that embarkment upon them committed a lineage to a definite and irreversible course of development? Here Dollo is ambiguous. He often wrote that certain specialized forms cannot become generalized, but these short, declamatory statements leave us wondering whether this irreversibility arises because specialized forms inevitably lose structures too intricate to be regained (the usual argument based on complexity) or because something inherent in the evolutionary process dictates that lineages must proceed from generalized to specialized forms (the orthogenetic argument based on programmed sequence). Refuting, for example, the link between ptyctodont arthrodires and holocephalians, Dollo wrote: "If ptyctodonts are holocephalians then the most ancient holocephalians are the most specialized. How, from this state, could they give rise to their successors. Impossible. And here is a new application of the irreversibility of evolution." 35 34. 1909b, p. 430; 1909a, p. 410. 35. 1907, p. 7.

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Dollo on Dollo's Law The solution to this problem is probably contained in Dollo's views on the limitation of evolution, for here we find the same ambiguity (see page 193). Limitation based on the inability of a very specialized form to adapt to new conditions leads to an irreversibility determined by the loss or irrevocable modification of complex structures. Limitation based on the curtailment of "plastic potential" in racial old age leads to an irreversibility determined by programmed sequence. Since he speaks of limitation in both senses, we must conclude that an orthogenetic interpretation of a few of Dollo's statements on irreversibility is not inconsistent with his view of the evolutionary process. Thus, Dollo must share a portion of the blame for the morass of confusion that his law generated in our literature. And yet, the text that defines irreversibility as an adjunct of orthogenetic theories does Dollo a great injustice, for only a very few of his statements could be fairly interpreted in this light and none need be. In conclusion, three senses of irreversibility may be discerned in Dollo's works: 1. An a priori assumption that a whole organism never reverts completely to a prior phylogenetic stage. 2. A testable hypothesis that a complex part of an ancestor never reappears in exactly the same form in a descendant. These two propositions are the heart of irreversibility; all of Dollo's statements can, and probably should, be tied to one of them. They have the same justification (a probability argument based on complexity) and play the same role (a method for the recognition of convergences). 3. Certain evolutionary trends are necessarily unidirectional. This interpretation can be attached only to a very few of Dollo's statements. If in Dollo's mind at all, it played an extremely minor role in his thought on irreversibility. II. THE DEBATE OVER IRREVERSIBILITY Tis with our judgments as our watches, Go just alike, yet each believes his own.

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A. Pope, Essay on Criticism The literature on irreversibility is a quagmire. I had harbored the naive hope of finding some chronological trend in opinion; either the happy discovery that accumulating wisdom drives out

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misinterpretation or the cynical result that the further we get from Dollo's writing, the less likely we are to read it and the more likely, therefore, to misrepresent. I find, instead, that the tendency to misread (or not read) is timeless: the same errors have been cropping up with the same frequency ever since the debate started. I have tried, therefore, to delimit what I consider the six major interpretations of Dollo's opinion. For several of these we have Dollo's own refutation of views attributed to him, recalling Marx's famous abjuration of "marxism." A primary division arises from the two principal meanings of irreversibility: Dollo's based on the improbability of reversion in complex structures, and the orthogenetic based on the necessity of following a programmed sequence. Among those who incorrectly imparted an orthogenetic interpretation to Dollo's views, we see two tendencies. 1. Orthogeneticists who cited their misunderstanding to support a theory of ineluctable trends. Deperet defined Dollo's law as "the fact that a lineage, having once embarked on the path of a determined specialization, can in no case turn back upon the road already travelled." We find him, a few pages later, using this definition to support a claim that "each phyletic branch has a geologic career in which we can distinguish a phase of youth, a phase of maturity, and finally a phase of senility or degeneration preparatory to extinction of the type."36 Likewise, Cuenot, who believed that "orthogenesis is preparatory to the future of lineages just as ontogenesis is preparatory to the future of an individual," interpreted Dollo's law to mean that certain trends were necessarily unidirectional.37 Beurlen, though not completely in the orthogenetic camp, shared the antimechanism of Deperet and Cuenot. He devoted an entire chapter to a supposed demonstration that the validity of Dollo's law demolishes a purely mechanistic interpretation of the natural world: "The knowledge that phylogenetic history is irreversible means that a mechanistic-causal interpretation, however it is constructed, either primarily Lamarckian or primarily Darwinian, cannot alone suffice for an understanding of phylogeny." 38 Dollo, a convinced mechanist, would have taken great 36. Charles Deperet, Les Transformations du monde animal (Paris: Ernest Flammarion, 1919), pp. 243, 246. 37. L. Cuenot, L'Evolution biologique, (Paris: Masson, 1951), pp. 49-51, 537. 38. K. Beurlen, Die stammesgeschichtlichen Crundlagen der Abstammungslehre (Jena: Gustav Fischer, 1937), p. 42.

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Dollo on Dollo's Law offense at such a use of his work, for he had stated explicitly39 that irreversibility offered no challenge to a mechanistic world view. 2. Darwinians who attack a fallacious orthogenetic interpretation, often with the very arguments Dollo used to support his version of irreversibility. Easton,40 for example, wrote: "About the same time that the doctrine of orthogenesis was proposed, a collateral hypothesis was suggested in Europe by Dollo. It was Dollo's belief that evolution was always progressive-that is, that creatures, once they started down a certain path, never retreated nor could they resume a former condition." To undermine this supposed definition of Dollo's law, Easton cited the return to water of ichthyosaurs and whales, an example used often by Dollo to substantiate his notion of irreversibility.41 Similar orthogenetic misdefinitions are proposed as Dollo's own and rejected by Beerbower and Ehrenberg.42 Four major arguments are presented by scientists who recognized at least a part of Dollo's claim-that reversibility of structure is the object of debate. 3. Dollo claimed only that complex structures could not be reacquired.43 This is not always valid because ancestral structures are preserved in early ontogenetic stages (due to acceleration) and may again become adult in paedomorphic forms. Nopcsa attributed the reappearance of the postorbital bar in mammals to such a process and stated:44 "The unexplainable but important fact, that the life-history of each individual is always a distorted recapitulation of the history of its whole phylum, gives the clue by which we can understand why a 39. 1905a, p. 130. 40. W. H. Easton, Invertebrate Paleontology (New York: Harper, 1960), p. 42. 41. 1912, p. 106, and 1922, p. 216. 42. J. R. Beerbower, Search for the Past (Englewood Cliffs, N. J.: PrenticeHall, 1960), p. 156; Kurt Ehrenberg, Palaozoologie (Vienna: Springer, 1960), p. 22. 43. The correct interpretation so far. 44. Francis Nopcsa, "Reversible and irreversible evolution; a study based on reptiles," Proc. Zool. Soc. London, (1923), 1058. The same point has been made, with different examples in: G. J. Fejervary, "Quelques observations sur la loi de Dollo et 1'epistr6phogenese en consideration speeiale de la loi biog6n6tique de Haeckel," Bull. Soc. Vaud. Sci. Nat., 53 (1920), 343-372; P. P. Sushkin, "Notes on the pre-Jurassic tetrapods from the U.S.S.R.," Trav. Inst. Pal6ozool. Acad. Sci. U.S.S.R. Leningrad, 5, (1936), 43-91; and, more recently by: M. A. Shishkin, "Morphogenetic factors and the irreversibility of evolution," Paleont. J., 3 (1968), 293-299.

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limited reversal of evolution can occur." Dollo had anticipated this objection and provided a counterargument based on the fact that "ontogeny is not a complete and exact recapitulation of phylogeny."45 Not only is recapitulation always imperfect (precluding the exact reacquisition of a structure), it is also far from universal in occurrence. Of the ontogeny of the turtle Dermochelys coriacea, Dollo wrote:46 if There must be a perturbation in recapitulation-since we refuse to admit perturbation, we arrive at a phylogeny in opposition to chronology, paleontology, ethology, etc. Let us avoid abusing a law whose fallacies have already been enunciated by the illustrious Fritz Muller; it has value only if we apply it with discrimination. Moreover, he wrote to Tilly Edinger: "It is clear, a priori, that ontogeny cannot be a complete and exact recapitulation of phylogeny. Just think how long it would then take for even a simple individual to develop I"47 4. Dollo claimed that no structural reversal of any kind was possible in evolution. Two misinterpretations are involved here since Dollo believed that no complete reversion of complex structures could occur. Many authors have cited incomplete reversions of complex structures as exceptions to Dollo's law. The secondary isodont teeth of cetaceans, recalling the dentition of ultimate reptilian ancestors, is a perennial favorite: Stromer and Scott invoked it and Rensch regarded it as an "unquestionable exception to Dollo's views.48 But Dollo had answered the very same objection in 1907: Now the evolution of the dentition of whales is one of the most beautiful examples of the irreversibility of evolution, since the secondary isodont dentition is not a return to the primitive 45. 1922, p. 216. 46. 1901, p. 20. 47. Letter of November 17, 1928. Dolo had enormous respect for Haeckel despite his doubts about recapitulation. He wrote to Tilly Edinger (letter of June 30, 1928): "I do not want you to compare me with Haeckell . . . We exchanged publications, but I never had a personal relationship with him. Nevertheless, a curious thing, he was interested in me and in my work. Abel went to see him several times and, each time, he asked: 'How is Dollo? What is Dollo doing?"' 48. E. Stromer, Lehrbuch der Palaozoologie, vol. 2, Wirbeltiere (Leipzig: B. G. Teubner, 1912), p. 288; W. B. Scott, A History of Land Mammals in the Western Hemisphere, (New York: Macmillan, 1929), p. 656; Bernhard Rensch, Evolution Above the Species Level (New York: Columbia University Press, 1960), p. 124.

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Dollo on Doao's Law isodont dentition but is an isodont dentition of completely different morphology. It is infuriating that M. von Arthaber chose to contradict before he had understood.49 Atavisms have often been cited as exceptions to Dollo's law.50 Abel5l devoted a lengthy chapter to dismissing this claim by showing that atavistic structures never produce complete reversion. Dollo dismissed it more gently: "Have you noticed my simian atavism on this photograph (Darwin's point on the ear). But it is only partial and that is a beautiful example of irreversibility 1"52 Other authors have tried to refute Dollo by pointing out that complete reversion occurs in simple structures. Back mutation is often cited.53 Stromer invoked the size reversion of dwarf hippos and elephants; Boulenger noted that lost vertebrae have been regained in several fish lineages.54 Most ironic are the statements of authors who unwittingly use Dollo's own formulation to refute their misconception of Dollo's law: Deeply entrenched is the conception that phylogenetic development is irreversible (Dollo's Law). But this is so only in certain cases, especially when we are dealing with the entire organism or complex organs. A reversion to phylogenetically earlier states can occur in simple structures . . . The unrestricted use of Dollo's law . . . as with the similarly extreme use of the biogenetic law, has led the study of phylogeny into too many errors of interpretation.55 5. Dollo did not claim that all evolution was irreversible, but only that lost structures could not be regained in the same form. Pressured by self-styled opponents of Dollo's law who brought up the irrelevant examples of reversion in simple structures cited above, many of Dollo's supporters restricted the law to a "sure thing," but emasculated it in so doing. Diener, and especially 49. 1907, p. 7. 50. Rensch, in Evolution, cites several standard examples. 51. Othenio Abel, Palaobiologie und Stammesgeschichte (Jena: Gustav Fischer, 1929). 52. Letter to Tilly Edinger, November 21, 1926. 53. Rensch, Evolution, p. 124; Walter Zimmermann, "Methoden der Phylogenetik," in G. Heberer (ed.) Die Evolution der Organismen (Stuttgart: Gustav Fischer, 1954), pp. 25-102. 54. Lehrbuch, p. 285; G. A. Boulenger, "L'Tvolution est-elle reversible? considerations au sujet de certains poissons," Compt. Rend. Acad. Sci., 168, (1919), 41-44. 55. Adolf Remane, "Die Geschichte der Tiere," in G. Heberer (ed.) Die Evolution der Organismen (Stuttgart: Gustav Fischer, 1954), p. 419.

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Abel, are identified with this restriction, and their opinion was copied by many later authors.56 Simpson referred to this practice as a "kindly tradition," but Dollo himself had disavowed it: "The irreversibility of evolution does not only apply to lost or reduced organs, but also to functional organs."57 The point is that in so restricting Dollo's law, its essential relationship to complexity of structure is obscured and its value as a general statement destroyed. 6. Dollo claimed only that complex structures could not be reevolved; this is a valid statement. Some short textbook statements have presented Dollo's own position in a favorable light;58 others, unfortunately a majority, expound the orthogenetic interpretation. Other works, which consider the question in greater detail, support both Dollo's formulation and his justification based on probabilities. Here we find the writings of Schindewolf, Blum, Muller, and, especially, Simpson. Muller, arguing from genetics, spoke of "the sheer statistical improbability, amounting to an impossibility, of evolution ever arriving at the same complex genic end-result twice." Blum, from a thermodynamic standpoint, stated that "the chances of retracing the steps of evolution over any distance becomes vanishingly small as the complexity of organisms and their environment increase.59 Thus few critics who attached Dollo's name to their discussion of irreversibility correctly presented what Dollo himself had said. I cannot avoid the feeling that these misstatements arise from unfamiliarity with the intellectual context of Dollo's irreversibility. For Dollo, a law of irreversibility functions as a guarantee that convergences can be recognized by preservation of some ancestral structure(incomplete reversion). Convergence 56. Karl Diener, Palaontologie und Abstammungslehre (Leipzig: Samml. Goschen, 1910); Othenio Abel, Grundzuge der Palaeobiologie der Wirbeltiere (Stuttgart: Schweizbart, 1912), and Palaobiologie; for example, in: W. K. Gregory, "On the meaning and limits of irreversibility in evolution," Am. Nat., 70, (1936), 517-528; G. S. Carter, Animal Evolution: A Study of Recent Views and Its Causes (London: Sidgwick and Jackson, 1951). 57. G. G. Simpson, The Major Features of Evolution (New York: Columbia University Press, 1953), p. 310; Dollo, 1909a, p. 397. 58. A. M. Davies, An Introduction to Paleontology (London: Thomas Murby, 1947); R. C. Moore, C. G. Lalicker, and A. G. Fischer, Invertebrate Fossils (New York: McGraw-Hill, 1952). 59. 0. Schindewolf, Palaontologie; H. F. Blum, Time's ArTrow and Evolution (Harper Torchbacks, 1962), p. 200; H. J. Muller, "Reversibility in evolution considered from the standpoint of genetics," Biol. Rev., 14 (1939), 27; G. G. Simpson, Evolution, and This View of Life (New York: Harcourt, Brace and World, 1964).

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Dollo on Dollo's Law is the major impediment to phylogenetic interpretations; phylogeny is the goal of paleontology. In this context, Dollo could scarcely have been excluding anything but complete reversal. When this context is not known, criticism may be based solely on the various vernacular senses of irreversibility; numerous interpretations (none of them Dollo's) will then arise. The seemingly endless and often acrimonious debates that have raged about the concept of irreversibility have almost always been based not on substantive disagreement concerning the course of evolution, but rather on the sheer semantic misunderstanding generated by using one term-"Dollo's law"-for a variety of contradictory concepts. III. IRREVERSIBILITYAND THE STATUS OF EVOLUTIONARYLAWS The nonrecurrence of experienced events must be one of the oldest notions of the human mind, for in any real experience our sensation of time is unidirectional and the irreversibility of history and of evolution seem to be corollaries of this.

H. Blum, Time's Arrow and Evolution, p. 179 Our textbooks of evolution usually describe Dollo's notion of irreversibility in conjunction with other supposed "evolutionary laws"-usually with "Cope'slaw" that body size tends to increase in phyletic sequences and "Williston's law" that large numbers of similar elements tend to be reduced to fewer differently specialized units. The attempt to order phylogenetic events into regularities sufficiently pervasive to be termed laws was a popular strategy earlier in this century. It was centered on the reductionist view that biology should be patterned on the formal structure of the physical sciences. W. K. Gregory, a major proponent of this strategy, held that "we ought logically to begin with the forces inside the hydrogen atom and work outward and upward through organic chemistry to man."60 The Newtonian synthesis had produced a set of descriptive generalizations that ordered complex results into a simpler lawful structure. Thus, it was argued, the maturation of evolutionary biology to true science depended on the discovery of lawful structure among phylogenetic events. The laws of Cope and Williston are attempts at descriptive 60. W. K. Gregory, "Basic patents in nature," Science, 78 (1933), 561566.

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generalization. Dollo's law, on the other hand, has a very different status. Previously, I divided Dollo's law into two statements: (1) The entire organism never returns to a former state. (2) A complex part of an organism never returns exactly to a former state. The first, as discussed on page 196, is no statement about data at all, but a necessary a priori assumption that phylogenies can be established, given the nature of evolution and the fossil record. The second seems to have the form of an empirically grounded statement, but the ambiguity introduced by varying interpretations of "complex" has robbed it of any precise meaning and general usefulness (see note 22). Almost any reversion can be excluded from its domain by claiming either that the structures involved were not sufficiently complex or that the genetic basis for an elaborate morphological change was simple. If this second part of "Dollo's law" is not a useful statement in arguments about specific phylogenies, what is its status and has it any importance? If we assume that complex evolutionary events generally have complex causes,6' then Dollo's law simply affirms that the results of evolution conform to our general notion of history as a sequence of unique phenomena.62 And Dollo's finest insight was that he provided as his justification of evolutionary irreversibility the very same argument advanced today for the uniqueness of historical events-the statistical improbability that the incalculable number of independent configurations antecedent to and comprising any historical event should ever occur twice. Thus, Dollo's law is not an adjunct of evolutionary theory. It is a statement, framed in terms of animals and their evolution, of the nature of history; or, put another way, it is an affirmation of the historical nature of evolutionary events. As is so often the case, we are indebted to G. G. Simpson for this perceptive interpretation: "That evolution is irreversible is a special case of the fact that history does not repeat itself. 61. The argument leveled against Dollo's law by Nopcsa and Fej6rvary (note 44) was based on a denial of this premise. They claimed that complex reversions could be produced by the reasonably simple mechanism of acceleration followed by paedomorphosis. In this sense, their argument is potentially the strongest of any leveled against Dollo's law, but it failed because nature doesn't work in the way they imagined. Yet even if it did, we could still preserve Dollo's law by claiming that such reversions were not really complex and that only reversions with complex causes should be covered by the law. This is what I mean in stating that almost any empirical challenge against the law can be refuted. 62. G. G. Simpson, This View of Life, and quote of H. Blum introducing this section.

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Doao on Dollo's Law The fossil record and the evolutionary sequences that it illustrates are historical in nature, and history is inherently irreversible." 63 This interpretation of Dollo's law is involved in our judgment upon the descriptive generalizations of Cope and Williston and upon the entire enterprise of lawmaking for phylogenetic results. Simpson has distinguished immanent from configurational properties of the universe (the former as "the unchanging properties of matter and energy and the likewise unchanging processes and principles arising therefrom"; the latter as "the actual state of the universe or of any part of it at a given time.64 Laws are framed for immanent properties: we are not interested in the melting behavior of a particular ice cube but in the properties of water in general. Physics rarely deals with the configurational; if its formal structure is lawlike, this is because it has excluded the configurational from its domain. The error made by reductionists who attempted to formulate laws for the results of evolution was that they assumed a similar focus for biology and physics. But biology often deals with the configurational and the search for so-called historical laws among such properties is not a fruitful endeavor. While I agree with Watson and Siever that there is no formal distinction between historical and non-historical science,65 there is a difference of emphasis. There are nomothetic undertones to the results of evolution-the principle of natural selection is among them-and it is here that our laws must be formulated. They must be based on immanent processes that produce events, not on the events themselves. The "laws" of Cope and Williston, based as they are on configurational properties, are not laws in the ordinary sense but descriptive generalizations of low-order probability that describe some common regularities without explaining anything. "Dollo's law" is not among these. Quite the contrary: since irreversibility is an acknowledgment of the historical nature of evolutionary events and since that very nature precludes the formulation of laws for these events, "Dollo's law" is a particularized statement of our reason for rejecting the approach to evolutionary biology that led to the laws of Cope and Williston. Dollo is done an injustice 63. This View of Life, p. 186. 64. Ibid., p. 122. Nagel makes a similar distinction between nomothetic and ideographic properties (Ernest Nagel, "The logic of historical analysis," in H. Feigl and M. Brodbeck [eds.], Readings in the Philosophy of Science [New York: Appleton-Century-Crofts, 1953], pp. 688-700). 65. R. A. Watson, "Is geology different? A critical discussion of The Fabric of Geology," Phil. Sci., 33, (1966), 172-185; Raymond Siever, "Science: observational, experimental, historical," Am. Scientist, 56, (1968), 70-77.

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when his views are relegated to the wastebasket of archaic strategies, for irreversibility is no outmoded historical law; rather, the search for historical laws is outmoded because we have now recognized the significance of irreversibility in Dollo's sense. Yet surely there is something ironic here, for Dollo himself was a reductionist and quite committed to the search for historical laws. In fact, when he presents his justification for irreversibility, his words betray the determinism that characterized most reductionist thinking prior to the advent of quantum physics: To repeat "perfectly determined individual variations in a perfectly determined order . . . we would have to admit the intervention of causes . . . in an exactly inverse order."66 I doubt that Dollo ever perceived the anti-deterministic implications of the larger generality of which his irreversibility forms a special case. And yet, if the operas of Wagner, which Dollo loved perhaps more than his fossils, are any guide, it is upon the content of the piece itself and not the intent of its author that we must judge a man's work.67 66. 1913, p. 59. 67. I thank Ernst Mayr, Director of the Museum of Comparative Zoology, Everett Mendelsohn, History of Science Department, Harvard University, and Carl Putz, Philosophy Department, De Pauw University for their careful and extensive criticism of the manuscript. A. S. Romer kindly lent me the correspondence of Dollo and Tilly Edinger and regaled me with the bits of human interest that substitute a living man for the abstract ideas gleaned from his published work.

APPENDIX THE LAWS OF EVOLUTION, by Louis Dollo (Translated from Bull. Soc. Belge Geol. Paleontol. Hydrol., 7 [1893], 164166). I. According to the brilliant conception of the immortal Charles Darwin (1809-1882): Evolution-the transformation of organisms-results from the fixation of individual useful variations by the influence of natural selection provoked by the struggle for existence. All species, animal or vegetable, which exist or have existed since the appearance of life on the globe, owe their origin to this fundamental law. II. But: 1. What is the cause of individual variations?

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Dollo on Dollo's Law 2. What is their amplitude? Is it small? Is it large? Is evolution extremely slow, or does it occur by rather rapid jumps? 3. From another viewpoint, is evolution reversible? Can an organism return (either totally or partially) to a former condition already realized in the series of its ancestors?-either by returning in a single jump or by passing, in reverse order, through the various stages which led to its origin. 4. Finally, is evolution limited or indefinite? Does every organism carry within itself a boundless power of metamorphosis, or must it necessarily become extinct after having run through a determined cycle? III. The solution of these questions is of great importance for the biologist, not simply for the enormous interest which they offer in themselves, but also because of their applications. IV. Mr. Dollo is of the opinion: 1. that evolution occurs by rather rapid jumps. 2. that an organism cannot return, even partially, to a former state already realized in the series of its ancestors. 3. that ali organisms must necessarily become extinct, after having run through a determined cycle which may, however, be extremely long. He expresses this by saying: Evolution is discontinuous, irreversible and limited. V. The author then presented his reasons for thinking that this must be so. Then he cited a large number of examples, drawn from living and fossil animals and from living plants, to support his viewpoints. VI. Mr. Dollo is happy to say that his ideas have been accepted by his mentor, Mr. A. Giard, Professeur i la Sorbonne, and by his good friend, Mr. P. Pelseneer, Professeur a l'tcole normale de Gand. He thanked these two naturalists for the cases of discontinuity and irreversibility which they had so kindly communicated to him (Mr. Giard: crustaceans, plants; Mr. Pelseneer: molluscs). He thanked two other of his best friends as well: Mr. J. Massart, Assistant A l'Institut botanique de l'Universit6 de Bruxelles, who pointed out to him many interesting facts related to discontinuity and irreversibility among plants; and Mr. G. Boulenger of the British Museum who called his attention to numerous aspects of the structure of living reptiles which have a considerable bearing on these questions. He also mentioned with satisfaction that Mr. L. Errera, Professeur a l'Universite de Bruxelles, agrees at least partially with his views. Finally, in conclusion, he stated that Mr. P. Hallez, Professeur a la Facult6 des Sciences de Lille, following his most recent studies on worms, concluded that evolution was discontinuous. VII. Mr. Dollo was led to these generalizations through his specialized research on fossil bones that he has been pursuing for twelve years at the Brussels Museum. He first announced them in his course at the Solvay Institute (University of Brussels) (Signed lesson of November 12, 1890). Later he returned to them, notably in Giard's Bulletin (September

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STEPHEN JAY GOULD 20, 1891) and in this Society's Bulletin (October 25, 1892). VIII. The author noted with pleasure that his ideas have been adopted without reservation by Mr. A. Lameere, Professeur a l'Universite de Bruxelles, in his Esquisse de la Zoologie (Brussels, 1892) and in the syllabus of his Cours sur le Transformisme (University extension; lesson 3; 1893). IX. Mr. Dollo intends to gather together in a small illustrated volume all the important cases of discontinuity, irreversibility, and limitation collected by him and his friends.6 X. Is this to say that the laws enunciated above are the only ones which direct the evolution of organisms? Not at all. There are many other fundamental laws: Examples: the law of recapitulation, the law of necessary regression, etc. Short Bibliography of Dollo's Work on Irreversibility "Les Lois de l'6volution," Bull. Soc. belge GMol.Pal. Hydr., 7 (1893), 164-166. "Sur la phylog6nie des dipneustes," Bull. Soc. belge Geol. Pal. Hydr., 9 (1895), 79-128. "Macrurus Lecointei, poisson abyssal nouveau, recueilli par l'exp6dition antarctique belge," Bull. Acad. r. Belg. Cl. Sc., (1900), 383-401. "Sur l'origine de la tortue luth (Dermochelys coriacea)," Bull. Soc. r. Sci. me4dic. nat. Bruxelles, 59 (1901), 17-40. "Eochelone brabantica, Tortue marine nouvelle du Bruxellien (Eocbne moyen) de la Belgique," Bull. Acad. T. Belg. Cl. Sci., (1903), 792-801. "Un nouvel opercule tympanique de Plioplatecarpus, Mosasaurien plongeur," Bull. Soc. belge GMol.Pal. Hydr., 19 (1905a), 125-131. "Les Dinosauriens adapt6s A la vie quadrupede secondaire," Bull. Soc. belge Gt6ol. Pal. Hydr., 19 (1905b), 441-448. "Les Ptyctodontes sont des arthrod6res," Bull. Soc. belge Ge'ol. Pal. Hydr., 21 (1907), 97-108. "La Palk6ontologie ethologique," Bull. Soc. belge GMol. Pal. Hydr., 23 (1909a), 377-421. "Les Poissons voiliers," Zool. Jahrb., 27 (1909b), 419-438. "Les Cephalopodes adaptes A la vie nectique secondaires et A la vie benthique tertiare," Zool. Jahrb. Suppl., 15 (1912), 105-140. "Podocnemius congolensis, tortue fluviatile nouvelle du Montien (Pal6ocene inf6rieur) du Congo et l'evolution des cheloniens fluviatiles," Ann. Mus. Congo belge, Geol. Pal. Miner., serie 3, Bas et Moyen Congo, 1 (1913), 47-65. "Les Cephalopodes d6rouls et l'irreversibilit6 de l'6volution," Bijdragen tot de Dierkunde, (1922), 215-227. 68. Such a volume was never published.

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ActionPropreand ActionCommune: The Localizationof CerebralFunction JUDITH P. SWAZEY Harvard University Program on Technology and Society Cambridge, Massachusetts

Throughout the nineteenth century, and into the twentieth, advancing knowledge about the brain's functions kept in perpetual motion a pendulum which swung between two polar beliefs. Especially as concerns the "psychic" functions of the cerebrum, upholders of "action propre" asserted that specific functions have specific loci within a major subdivision of the brain while supporters of "action commune," or field theory, maintained that a structure such as the cerebrum exerts a unitary or equipotential action. The effective impetus to a detailed scientific study of the brain as the "organ of mind" came in the nineteenth century, in part through the impact upon scientific thought of the physiologic doctrine of phrenology.' Phrenology's founder, Franz Joseph Gall (1758-1828), and its chief popularizer, G. Spurzheim (17761832) sought to establish empirically the postulates that brain is the organ of mind and that, in producing mental phenomena, brain has a highly specific action propre. In emphasizing the significance of Gall's and Spurzheim's work, however, one must realize that both of their postulates were well established, at least speculatively, before the nineteenth century. That there is an intimate connection between brain and soul or mind is an idea which has been held by most thinkers since 1. Gall defined the physiology of the brain as "la connaissance des facultes et des qualites primitives, et du si6ge de leurs conditions mat6rielles."-Franz Joseph Gall, Anatomie et physiologie du systeme nerveux en general et du cerveau en particulier, avec des observations sur la possibilitM de reconnaitre plusiers dispositions intellectuelles et morales de l'homme et des animaux par la configuration de leurs tates, 4 vols. (Paris, 1810-19), III, 4. Journal of the History of Biology, vol. 3, no. 2 (Fall 1970), pp. 213-234.

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Galen, following the lead of the Alexandrian anatomists, located the psychic faculties in the brain's substance. Galenists of later centuries housed the soul's "sensitive, motor, and intellectual faculties" in the fluid-filled ventricles of the brain. A shift from ventricular to specific brain localization was suggested by the seventeenth-century anatomist and physiologist Thomas Willis, in his classic work Cerebri Anatome (1664).2 Studying the gross divisions of the brain, Willis found that cardiac arrest was caused by manipulation of the cerebellum, and death by its removal, and concluded that the cerebellum is the seat of involuntary motions. The medulla, he believed, was the common trunk of the cerebrum and cerebellum, coming into "rapport"with the former through the "internodes," or basal ganglia. Believing the cerebrum to be the seat of voluntary motions, he localized memory and will in the convolutions, imagination in the corpus callosum, sense perception in the corpus striatum, and certain emotions in the base of the cerebrum. Returning to the more general of Gall's two postulates, the belief that there is some such entity as conscious mind and that it is somehow dependent upon brain, was firmly entrenched in biological and/or philosophical thought by the authority of Cartesian dogma. Descartes attempted to resolve Galenian ambiguities concerning the status of the senses by providing a location for nonextended secondary qualities in a real entity, the "thinking substance," or res cogitans. The soul, joined to the whole body because "it is one and in some manner indivisible," interacts with the animal spirits in the brain, directs them, and is altered by them through the pineal gland, or conarium, located above the fourth ventricle.3 Yet, though mind and body interact, Descartes clearly did not identify brain with mind. The Cartesian dualism is a complete one: the soul, or mind, which includes innate ideas and all phases of conscious life dependent upon the action of external agencies, "can work independently of the brain."4 Descartes thus taught that through a part of the brain a nonextended substance comes into effective contact with the world of extension. But from his statements a second generation of Cartesians, perhaps 2. J. Soury, "Cerveau," in Dictionnaire de physiologie, ed. C. Richet (Paris: G. Balliere et Co., 1897), II, 566f; H. Isler, Thomas Willis, 16211675. (New York: Hafner, 1968). 3. Rene Descartes, Passions of the Soul, in Philosophical Works, trans. E. S. Haldane and G. R. T. Ross (Cambridge [Eng.] University Press, 1911), I, art. 30-32, 34, 41. 4. Rend Descartes, Meditations, ii, reply to objection 3, in Phil. Works, II.

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Action Propre and Action Commune unable to comprehend a nonspatial entity existing independently of the extended world, came to think of mind as something localized and wholly confined in the body. The conarium became the "seat of the soul". This popular (mis)interpretation of Cartesian dualism created the problem which subsequent theories of epistemology and perception have sought to solve: how can that which is unextended know and achieve purpose in an extended universe? The subsequent tangled historical disputes over the relationship between "mind and body" is a central thread in our story for, as we shall see, Gall's work was stimulated by French sensationalism while Flourens, opposing Gall's organology, sought to restore the Cartesian unity of the soul. PHRENOLOGY:ACTION PROPRE The doctrine of physiognomy or craniology, labeled "phrenology" in 1815, had its immediate genesis in the anatomical observations of the young Franz Gall, who believed he could correlate some of his classmates' mental characteristics with the shape of their heads. His belief in this correlation principle grew stronger when he went on to observe the inmates of prisons and insane asylums whose mental traits were regarded as established because they had led their possessors to their present status. Gall began lecturing on his new doctrine of physiognomy at Vienna in 1795, and was joined there by Spurzheim in 1808. On March 14, 1808, the two men presented a memoir as candidates for admission to the Institut de France. The memoir, detailing many of Gall's excellent and original anatomical researches, contains a succinct statement of the nature of, and supposed anatomical bases for, phrenology: Le cerveau se compose d'autant de systemes particuliers qu'il exerce de fonctions distincts. Or ces idees physiologiques derivaient de faits anatomiques, a savior, que les nerfs naissent des divers amas de substance gris, et que les divers systemes particuliers du cerveau resultant de la pluralite des faisceaux s'epanouissant dans les ganglions de la base et dans les circonvolutions.5 5. F. Gall and G. Spurzheim, Recherches sur le systWme nerveux en general et du cerveau en particulier: Memoire present6 a l'Institut de France, le 14 Mars, 1808; suivi d'observations sur la rapport qui en a fait 6W cette compagnie par ses commissaires (Paris, 1809), p. 228.

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Although Gall, from the foregoing quotation, believed that the physiologic tenets of phrenology were adduced from anatomical "facts," students of Gall's writings from Flourens on have pointed out that the converse is true: Gall was first of all a phrenologist, and undertook his studies of brain anatomy for a post hoc validation of his belief in action propre. One may, following Bentley's lead,6 seek for the foundations of Gall's organology in his adherence to French sensationalism and German faculty psychology. The French sensationalists most often and respectfully cited by Gall include CondiHlac (1715-1780), Bonnet (1720-1790), and Cabanis (1757-1808). These thinkers, in essence, centered their work upon an acceptance and modification of John Locke's epistemology. Locke, attempting to resolve the problems posed by the Cartesian dualism, came to stand for the concept of the mind as a tabula rasa. For our purposes, the central point of the tabula rasa is Locke's contention that the mind derives the "materials of reason and knowledge" from two sources: from "observations employed about external sensible objects," and from "the internal observations of our minds perceived and reflected on by ourselves." 7 Condillac, who began by completely accepting Lockean epistomology, came to reject reflection as a source of knowledge.8 In abolishing reflection he logically should have, but did not, recognize the Humian predicament of having no uniting principle to connect isolated and unintelligible sensory phenomena and thus make knowledge, the association of ideas, possible. Gall, however, saw the predicament and offered a solution. Mind is not only compounded of various sensory impressions but is also organized. Just as there is a material basis for sensations themselves, so there must be a material basis for the organization of mind.9 For Gall, the soul's "faculties" developed in correspondence with their proper cerebral organs, just as for Condillac knowledge grew by the addition of new senses.10 6. M. Bentley, "On the Psychological Antecedents of Phrenology," Psychol. Monographs, 21 (1915), 102. 7. John Locke, An Essay Concerning the Human Understanding (1690), ed. A. C. Fraser, (New York: Dover, 1959), vol. II, chap. 1, par. 1, notes 1-4. 8. E. B. Condillac, Traits des sensations (1754), in Oeuvres completes (Paris, 1798), III, 3, 6. 9. Gall, Anatomie, III, 231-232. 10. Flourens suggested that Gall saw an analogy between the senses' functions and the soul's faculties because he "saw that sensory functions are distinct and wanted the soul's faculties to be equally distinct"-De la phrenologie, (Paris: Gamier Freres, 1863), p. 63.

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Action Propre and Action Commune Functional interaction among brain structures was demonstrated after Gall. But the idea of interaction, essential to phrenology, was seen before Gall in Cabanis' belief that "thought" depends upon the "intimate organization" and the "integrity" of the brain." In the Anatomie,12 Gall paralleled Cabanis' belief that the external senses provide the materials for reason while the internal organs regulate instinctive life, and that the diverse functions of the brain serve to combine and rearrange sense impressions, attach signs to them, and thus produce thought. The sensationalists, then, turned to the structure of the brain and nervous system to account for both the diversity of sensation and the unity of consciousness, believing that psychic phenomena such as attention, memory, and will result from a combination of sensory excitations in the brain. Gall, not content to rest solely with sensationalism, elevated the brain's integrative and transforming functions to "higher faculties" or "plural intelligences" with strictly localized organs. The atmosphere in which Gall matured at Strassburg and Vienna was that of the "faculties" of the German empirical psychologists. Wolff wrote his Psychologia Empirica in 1732, his Psychologia Rationalis in 1740. Crusius' (d.1775) revision of Wolff's potential faculties into forces of judgment, imagination, thought, and so on, seems to have been the current doctrine during Gall's era. A link with sensationalism was provided by Karl Franz von Irwing (d. 1801), who held that both sensations and the most abstract integration of ideas have bases in the brain's fibrous structure. We find, then, that Gall's phrenology is a blend of the French and German schools of his time, a blend in which he replaced "the empty causes of Wolff by the organic causes of anatomy and sensationalism." 13 Gall was well equipped to seek for the "organic causes of anatomy." His skill as an anatomist is best reflected in the tribute of his severest doctrinal critic, Pierre Flourens: "Je n'oublierai jamais l'impression que j'eprouvai la premiere fois que je vis Gall dissequer un cerveau. II me semblait que je n'avais pas encore vu cet organe." 14 In evaluating Gall-the-anatomist, however, Flourens wisely distinguished between his "general anatomy," of which "much is spoken," and 11. P. Cabanis, Rapportes du physique et du moral de l'homme (1788), in Oeuvres completes de Cabanis (Paris, 1823-1825), III, 189. 12. Gall, Anatomie, III, 10. 13. Bently, Psychol. Monographs, 21 (1915), 111. 14. Flourens, De la phrenologie, p. 19.

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his "special anatomy" of cerebral organs, of which "Gall himself speaks as little as possible." 15 Having experimentally demonstrated the validity of assigning intellectual functions such as perception exclusively to the brain, rather than to the sense organs,16 Gall's "special anatomy" had to serve a double purpose. First, it had to show that no one part of the brain is the seat of mind, and, second, that the postulated "cerebral organs" which house the "faculties" are built in the same way as other functional nerve units. To both Gall and Spurzheim, Bichat's interpretation of the sympathetic nervous system revealed the pattern for all nervous components of the body. With Bichat, they denied the existence of a sympathetic nerve, holding instead that there is merely a sequence of communications between ganglia of various regions. Each ganglion has an independent, isolated action, and "each emits in different ways a multitude of ramifications which carry to their respective organs the radiation of the focus from which they derive." 17 Believing that function elucidates structure, Gall and Spurzheim formulated a purely functional rather than morphological definition of the nervous system. Attempting to describe the brain in a manner compatible with their general view that the nervous system consists of many structurally and functionally independent units, they began with the traditional division of the brain mass into cerebrum and cerebellum, each composed of gray and white matter.'8 Two essential features of these structures' anatomy are the "apparatuses of 'formation and of reunion'." Discussing the apparatus of formation, Gall noted that since the brain consists of several different divisions with different functions, it must develop from different fascicles, each fascicle composed of "diverging fibers." The nature of this proposed schema of brain development may be illustrated by Gall's discussion of the cerebrum: We see that the original fascicles are here produced by the gray substance of the medulla oblongata, and reinforced at different places by particular masses of gray substance; and that consequently everything here is subject to the same laws as are the nervous systems of the abdomen, chest . . . and 15. Ibid., p. 61. 16. Gall, Anatomie, II, 251. 17. Gall and Spurzheim, Rechlerches, p. 76: trans. 0. Temkin, "Remarks on the Neurophysiology of Gall and Spurzheim," in Science, Medicine, and History, ed. E. A. Underwood. (London: Oxford University Press, 1953), II. 18. Gall, Anatomie, I, 66, 68.

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Action Propre and Action Commune cerebellum . . . We see the fascicles of the brain expanding successively, so as to arrive at the end of their formation and to become the organs of the noblest and most important functions of the animal organism.19 In the foregoing statement, as elsewhere, Gall stresses the importance of the "law of successive reinforcements." 20 To its author, the "law" explained how the large mass of the hemispheres could originate from the brain's common trunk, the medulla, and, most important, suggested how the plurality of "cerebral organs" could arise. For the modern reader, as Temkin observes,2' perhaps the most "provoking"part of the special anatomy is the idea that the functional part of the cerebral organs is to be found in the gray matter covering the fibers rather than in the substance from which they originated. Here, notes Temkin, "Gall and Spurzheim are both very modern and at the same time very remote from modern concepts". "The convolutions of the brain", Gall asserted, "are nothing but the peripheral expansions of the fascicles composing it; therefore the convolutions of the brain must be recognized as the part where the instincts, sentiments, penchants, talents, and, generally, the moral and intellectual forces are exercised." 22 To give the theory of cortical localization general plausibility, Gall and Spurzheim had to assume that the nervous system's functional unity originates and terminates in the gray matter. Further, since complex mental acts depend on cooperation between the "cerebral organs," it was vital to hypothesize that the terminal gray matter can communicate with the corresponding gray matter of other units. This necessary communication was anatomically provided for by the "apparatus of reunion." 23 Since Gall felt-although unable to demonstrate it-that the apparatus of formation's fibers terminated in the cortex, he postulated that the apparatus of reunion is composed of "reentering fibers" which originate in the cortex.24 Various parts of 19. Ibid., p. 200: trans. 0. Temkin, in "Remarks on the Neurophysiology of Gall and Spurzheim." 20. Gall and Spurzheim, Recherches, p. 66. 21. "Remarks on the Neurophysiology of Gall and Spurzheim," p. 287. 22. F. Gall, Sur les fonctions du cerveau et SUT celles de chacune de ses parties,

(Paris,

1822-25),

II, 13.

23. Gall, Anatomie, p. 201f. 24. By "diverging" and "re-entering" fibers Gall meant, roughly, what are now called projection fibers and commissural and association fibers. To present neuroanatomists the most confusing element in Gall's discussion is his lack of differentiation between descending and ascending projection

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the apparatus of reunion include the re-entering fibers of the cerebellar pons, and the anterior and posterior commissures, fornix, and corpus callosum of the cerebrum.25 We have seen that Gall's study of brain anatomy was based upon his functional definition of the nervous system and oriented toward proving the existence of his cerebral organs. In this orientation lay the fatal weakness of Gall's "special anatomy." For, as Flourens remarked, "chose etrangel"-although all of phrenology rests upon the reality of these organs, neither Gall nor any of his followers says precisely what they are.26 Gall, indeed, carefully stated that he did not pretend to explain the faculties by reference to cerebral organs, but that he did find the brain's structure to have a "necessary and immediate relation to their function."27 Phrenology's founder thus opened himself to Flourens' charge that he, in truth, never had a decisive opinion about cerebral organs, that he "never saw them but only imagined them for faculties." Gall "commence par imaginer une hypothese, et puis il imagine une anatomie pour son hypothese." 28 In view of its considerable lack of factual basis, one may concur with Temkin's judgment that the "great attractiveness of [Gall and Spurzheim's] anatomical demonstrations lay in their giving physiological meaning to the structure of the brain. At a time when many of the best anatomists did not dare go beyond strict morphology, Gall and Spurzheim offered a theory which was simple as well as most comprehensive."29 Gall's and Spurzheim's "cerebral physiology," phrenology, was at once as simple and as comprehensive as the "special anatomy" upon which it was purportedly based. The first of phrenology's three central tenents is that the skull's exterior shaping corresponds to that of its interior and to the brain's conformation. For, in keeping with his belief that function determines form, Gall held that the formation of the "eminences" which mark the loci of faculties is determined in embryogenesis, and that the skull then forms to conform with these eminences. Secondly, phrenology asserts that mind can be accurately and fibers. Since Gall held that the brain originates from the medulla, all his "projection" fibers are anatomically descending but functionally both ascending and descending (Temkin, "Remarks on the Neurophysiology of Gall and Spurzheim," p. 288). 25. Gall, Anatomie, pp. 201, 459. 26. Flourens, De la phrenologie, p. 62. 27. Anatomie, I, XXV. 28. Flourens, De la phrenologie, p. 62. 29. "Remarks on the Neurophysiology of Gall and Spurzheimi," p. 289.

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Action Propre and Action Commune meaningfully analyzed in a number of separate "faculties." Blending French sensationalism and German faculty psychology, Gall held that each faculty or "intelligence" has its own perception, memory, judgment, and so forth. Thus, mind or "intelligence proprement dit" is merely "l'expression collective de toutes les facultes, ou meme le resultat de leur action commune et simultanee."30 Gall's list of the twenty-seven innate faculties31 was derived chiefly from the list of the Scottish-school psychologists, Thomas Reid and Dugal Stewart.32 Spurzheim, in his elaboration of Gall's phrenology, added seven faculties, revised their terminology, and established a new and more complete topography. As anatomists have failed to validate the signficance of the skull's shape, so too have psychologists and neurophysiologists failed to establish the existence of phrenological "faculty units." The final and central phrenological proposition, as I have indicated in discussing Gall's special anatomy, is that "chaque intelligence a son organe propre,"33 and that these organs are differentially localized in the cerebral convolutions. Accordingly, an excess in any faculty is correlated with enlargement of its cerebral locus, while a recession denotes lack of the faculty. Phrenology's most obvious and fatal flaw, as critics soon perceived, is the fact that the cerebral organs could not be physically demonstrated. This finding in turn offered a convenient "fudge factor" for practioners of phrenology because it provided for innumerable loopholes in the doctrine's interpretive method. For instance, if a correlation between a given faculty and its cerebral locus proved inaccurate, the phrenologist could account for the failure by asserting that expression of the faculty in question had been suppressed or altered by other, more dominant faculties. From the time of its first official promulgation in the 1808 memoir, when it still seemed scientifically plausible, phrenology was never generally accepted as a science. That scientists immediately recognized phrenology as, at best, a controversial and difficult doctrine is seen in the cautious conclusions by the committee which reviewed the memoir, a committee chaired by the eminent Georges Cuvier. It is necessary to repeat again, if only for the instruction of 30. 31. 32. (New 33.

Anatomie, IV, 341. Ibid., II, 3; III, 81. Edwin G. Boring, A History of Experimental Psychology, York: Appleton-Century-Crofts, 1950), pp. 205-209, 458. Gall, Anatomie, IV, 319, 323, 327, 341.

2nd ed.

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the public, that the anatomical questions with which we have been occupied in this report do not have an immediate and necessary relation to the physiological doctrine put forth by M. Gall on the functions and the influence of the relative volume of the different parts of the brain, and that all that we have brought out concerning the structure of the encephalon would be equally true or false without there being the least thing to conclude from it for or against the doctrine, which can only be judged by totally different means.34 Within a few years Pierre Flourens and his followers would produce evidence to show that phrenology's major tenets clearly lacked valid bases in anatomical and physiological fact. In the interim, the major grounds for the scientists' rejection of Gall's doctrine rested upon philosophical grounds. Phrenology's analysis of the mind into faculties with spatially discrete loci violated the cherished Cartesian dogma of the unity of the soul, and, by making beliefs such as liberty and morality mere results of cerebral interactions, it seemed to destroy "free will." The essence of these immediate reactions to the philosophical consequences of phrenology are seen most clearly in Flourens' later charge to Gall: Vous ne dites rien de l'unite de l'intelligence, de l'unite du moi, ou vous la niez. Mais l'unite de l'intelligence, l'unite du moi, est un fait sens intime; et le sens intime est plus fort que toutes les philosophies. . . . Gall renverse la philosophie ordinaire, et puis il veut que toutes les consequences de la philosophie ordinaire subsistent. II suprime le moi, et il veut qu'il ait une 'ame. II suprlme le libre arbitre, et il veut qu'il y ait une morale.35 The storm of criticism which broke over Gall's highly specific psychophysics had a catalytic effect upon the research scene of the time. In particular, to decisively confirm or refute the existence of "plural intelligences" housed in "cerebral organs," scientists had to extend existing knowledge of the nature of and relations between brain structure and functions. By 1850, 34. Memoires de la classe des sciences math6matiques et physiques de l'Institut de France (1808), p. 160: translated by E. Boring in Experimental Psychology, p. 59. 35. Flourens, De la phrenologie, pp. 30, 44. While scientists largely rejected phrenology, it had a deep and lasting popular appeal. The doctrine, spread throughout Europe and America by such men as Spurzheim, George Combe, and the Fowler brothers, flourished for a century among a broad range of lay groups.

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Action Propre and Action Commune through discoveries frequently couched against Gall's tenets, the physiology and neuroanatomy of the brain was established as a central problem in the study of the nervous system. As Boring has observed, Phrenology was playing its ambiguous role as cause and symptom of the Zeitgeist, which was moving mind away from the concept of the unsubstantial Cartesian soul to the more material neural function. Phrenology was wrong only in detail and respect of the enthusiasm of its supporters.36 PIERRE FLOURENS: ACTION PROPRE ET ACTION COMMUNE At the beginning of the nineteenth century, in concordance with philosophical thought, the prevailing doctrine of anatomical schools held that the whole brain is a common sensorium; that the extremities of the nerves are organized, so that each is fitted to receive a peculiar impression [which] is carried along the nerves to the sensorium, and presented to the mind; and that the mind, by the same nerves which receive sensations, sends out the mandate of the will to the moving parts of the body.37 With Gall's and Spurzheim's 1808 memoire the pendulum swung sharply, if briefly, from this concept of total action commune to the total action propre of Gall's organology. But, in the reaction against phrenology, researches begun by men such as Charles Bell and Luigi Rolando began immediately to move the pendulum back toward action commune. By 1825, in Pierre Flourens' concept that the brain functions by both an action commune and an action propre, the pendulum seemed to have stabilized midway between Gall and Descartes. Charles Bell's 1811 Idea of a New Anatomy of the Brain, in which he announced his famous experiments on the functions of the dorsal and ventral spinal nerves, used those experiments and clinical observations to controvert Gall's functional atomism. For Bell, the cerebrum's action propre controls intelligence, and the same principle in the cerebellum controls unconscious, involuntary activity. Both "grand divisions of the brain," in conjunction with the nerves, effect an action commune: to endow 36. Boring, Experimental Psychology, p. 57. 37. C. Bell, Idea of A New Anatomy of the Brain (London: Strahan, Preston, 1811.)

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"the frame of the body with the characters of life" and "hold the vital parts together . . . as one system." His allocation of cerebral and cerebellar functions was determined largely by his study of the course and function of specific nerves, especially his erroneous linking of the cerebellum with posterior, and the cerebrum with anterior, spinal nerves. In Gallian-like tones, Bell further argued for an equipotential action propre on the basis that "the brain . . . has grand divisions and subdivisions; and as the forms exist before the solid bones enclose the brain . . . they are evidently not accidental . . . but have a correspondence with distinctions in the uses and parts of the brain." Finally, on the bases of clinical observations, his own experiments, and "strict anatomy," Bell agreed with Gall's localization of psychic functions in the cerebral convolutions. Charles Bell never claimed priority over Flourens in "correctly" determining the functions of different brain structures. Luigi Rolando, however, did claim priority on the basis of an 1809 publication in which, drawing upon pre- and postmortem clinical observations, he stated that the hemispheres are "the principal seat of the immediate cause of sleep, of dementia, of apoplexy, of melancholia, and of mania." 38 Although, as Flourens pointed out, this statement is equivalent to localizing higher mental functions in the cerebrum, it does not assign intelligence and perception exclusively to the hemispheres. Further, opposing Gall and Bell, Rolando erroneously held that the cerebrum's activity is due to the great motility of its fibers, thus making white rather than gray matter basic to psychophysical functions. Drawing upon evidence indicating that all sensory nerves of the head except the olfactory and visual run to the medulla, Rolando located sensation in this structure rather than in the cerebrum. The work of M. Lorry (1760) and J. J. C. LeGallois (1809)39 had shown that the medulla is essential to life because it contains the "noeud vital" ("vital knot," or, today, respiratory center). As the principal seat of sensibility, the vital knot became, for Rolando, the new sensorium commune. Rolando's chief experiments were directed toward the func38. Soury, Dictionnaire de physiologie, ed. C. Richet, pp. 615-616. 39. Legallois, too, was led to the principle of functional localization by his researches: "Every time that a certain portion of the brain or cord is destroyed a function ceases abruptly . . . It was by this method that I discovered the location of the respiratory center, and it will be by this method, that, up to a certain point, we will discover the uses of certain parts of the brain."-ExpOriences suT le principle de la vie (Paris: D'Hautel, 1812), pp. 142-43.

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Action Propre and Action Commune tions of the cerebellum, which he thought was the organ for the preparation and secretion of "nervous force." Using the recently developed Voltaic pile, he stimulated the brain and found that muscular contractions became increasingly violent as the electrodes approached the cerebellum. The experiments were crude, and one is not sure precisely where his stimulus was effective. But his gross findings were clear enough to have him designate the cerebellum as the "battery" from which "nervous energy" is derived. In view of the history of researches into cerebral localization, Pierre Flourens exaggerated his originality when he said, of his 1822 memoire "ca elte a premiere fois que les diverses masses du cerveau ont ete distinguees par leur fonctions."40 Yet few contemporaries paid heed to priority claims such as Rolando's, for his localizations, particularly those drawn from clinical inferences were ill-defined, and his theories did not meet experimental testing. In contrast, Flourens was led to his conclusions concerning action propre and action commune by experiments which stand today as models of control and precision. Physiologists, noted Flourens, had long been confused by observing two equally certain facts: the specialization of our organs, which creates functional diversity, and the subordination of this diversity to the unity of the organism.41 Working by two guiding principles, he set out to resolve this confusion by determining the functions of different parts of the brain. Experiments, Flourens held, must bear directly upon one's conclusions. Thus, in place of the philosopher's rationalistic methods or the use of indirect clinical inference, Flourens relied upon direct observation of the relation between a part of the brain and its function. In fulfilling his first principle, he dealt solely with correlations between the intelligence and instincts and brain structures of lower animals, preferring to leave the problem of "human reason" to "Descartes and his successors." 42 Working chiefly with pigeons, dogs, and rabbits, he pioneered the method of extirpation of parts. By developing techniques which enabled him to operate precisely, without multilating tissue, he could be 40. P. Flourens, etudes vraies SUT le cerveau (Paris: Garnier Fr6res, 1863), p. 132. As a protege of Cuvier, Flourens' major researches on the brain were presented by Cuvier to the Academie des Sciences in 1822 and 1823. Portions of the memoires were first published in the Arch. Gen. de Med. 2:321 (1823), and, in their entirety, were published in book form as Recherches experimentales in 1824 (2nd ed., 1842). 41. Flourens, A:tudes vraies, p. 194. 42. Ibid., p. 212.

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sure, as a Rolando never could be, of exactly where ablation caused cessation of a given function. Flourens' description of the effects of cerebellar extirpations in the dog illustrates his second guiding principle, which demands the isolation of that part whose function is to be determined. The description is so lucid, as Fulton commented, that it could serve for any modern textbook.43 I removed the cerebellum in a young but vigorous dog by a series of deeper and deeper slices. The animal lost gradually the faculty of orderly and regular movement. Soon he could only walk by staggering in zig-zags . . . He had all his intellectual faculties, aRlhis senses; he was only deprived of the faculty of coordinating and regularizing his movements. Fulfillment of the principle of isolation of parts requires a clear prior idea of the functional relationships one wishes to study. On anatomical grounds Flourens chose to study as separate units the hemispheres, cerebellum, corpora quadrigemina, spinal cord, and nerves. Of his many first-class reports on the effects of extirpation, the succinct description in his 1822 memoir of the pigeon whose hemispheres had been extirpated may be cited as perhaps the best: It held itself erect very well; it flew when I threw it into the air . . . the irises of both eyes were very mobile, nevertheless it did not see; it did not hear, never moved spontaneously, assumed almost always the appearance of an animal asleep or drowsy . . . When I left it to itself, it remained calm and absorbed; in no case did it give a sign of volition. In a word, picture to yourself an animal condemned to perpetual sleep, and deprived even of the faculty of dreaming during this sleep; such, almost exactly, had become the state of this pigeon whose hemispheres I had removed. Of a similarly operated pigeon, he added: "If it encountered an obstacle it collided with it . . . again and again. . . If, however, only one hemisphere was removed, the animal immediately lost the sight of the opposite eye." As a result of such extirpation studies, Flourens became the first to show by experiment that vision depends upon the integrity of the cerebral cortex. Of 43. J. Fulton, Selected Readings in the History of Physiology (Springfield, Ill.: Charles C. Thomas, 1930), p. 266; Flourens, Recherches, translated by J. Olmsted in "Pierre Flourens," Science, Medicine and History, II, 295.

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Action Propre and Action Commune broader significance, however, is the generalization which he formulated in his 1823 memoir: "All perception, all volitions, occupy the same seat in these [cerebrall organs; the faculty of perceiving, of willing, merely constitutes therefore a faculty which is essentially one."44 With this statement Flourens most clearly expressed the essence of his physiology: the belief in unity of action in different parts of the nervous system. Belief in equipotential function for each major brain division was strengthened by the further discovery that the hemispheres can lose part of their substance without loss of function, and that, depending upon the amount of tissue extirpated, a lost function can be completely reacquired. Flourens observed that as he increased the amount of tissue extirpated in a given portion of the cerebrum, the exercise of that locus's function became progressively weaker; in addition, the functional energy of every other portion of the cerebrum was reduced until, "as one sensation is lost completely, all of them are. Consequently, there is no different origin for any of the faculties nor for any of the sensations, [although] the different sense organs nevertheless have a distinct origin in the cerebral mass." 45 Turning to the cerebellum, experiments such as the one previously cited on the dog led Flourens to conclude that this unit functions to coordinate movement and locomotion. In his 1822 memoire, he compared the gait of a decerebellate pigeon to that of a drunken man. Sir Charles Sherrington later credited Flourens' interpretation of this phenomeon as marking the formal introduction into physiology of the idea of nervous coordination.46 A third "first" reported in the 1822 memoire resulted from experiments on extirpation of the frontal areas and basal ganglia. Flourens confirmed the fact that the corpora quadrigemina are the visual center of the brain, and went on to show that uni44. Translated by Olmsted in "Pierre Flourens," p. 293. 45. From Flourens' Recherches, translated by W. Dennis in Readings in the History of Psychology (New York: Appleton-Century-Crofts, 1948). Dennis literally translated the French "sensation," although, with respect to the cerebrum, Flourens refers to the modern term "perception." 46. E. Schafer, Textbook of Physiology (Edinburgh: Y. J. Pentland, 1900), II, 909. In his 1823 memoir Flourens elaborated his idea that cerebellar ablation produces effects similar to those of alcohol. Comparing a decerebellate sparrow to one given drops of alcohol, he found that, after both had lost coordination, the drunken bird went on to lose its "higher mental" functions. He concluded that, after a certain amount is consumed, alcohol's action extends from the cerebellum to other parts of the brain.

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lateral ablation of the corpora, while producing contralateral ocular disturbances, does not abolish movement of the iris. Flourens' studies of the medulla, cord, and nerves chiefly extended rather than originated exact knowledge of these units' functions. He repeated the observations of Lorry, Legallois, and Rolando on the cessation of respiration and other involuntary

actions when the medulla is transected at various levels.47

For

Flourens, as for his predecessors, the medulla was the body's 'Corganof conservation," a nerve center which unites volitions before they are executed and orders sensations before they are perceived.48 Within the medulla, the vital knot's unique control over life and death made it "une chose merveilleuse et d'un ordre supreme que la grande specialite d'action qui gouverne le systeme nerveux." 49 As did the contemporaneous work of Bell and Magendie, Flourens' researches showed that the cord's function is conduction while that of the nerves is transmission. In connection with these researches, another first was his demonstration of the action of anaesthetic agents on the nervous system of lower animals. He found, for example, that an etherized dog showed no evidence of pain when the cord was exposed and the dorsal nerve roots pinched.50 One can readily see, as Olmstead remarked, why Flourens "got so excited over the action of anaesthetics." 51 For, extending his observations to include the medulla and cerebrum as well as the cord, he noted that the etherized animal first lost "the principle of sensation, then the principle of movement, always in this order."52 From these 47. Flourens, "Nouvelles experiences sur le syst6me nerveux," Mem. de l'Acad. des Sci., 9 (1826), 478. 48. Flourens, ttudes vraies, p. 195. 49. Ibid., p. 133. Between 1851 and 1858, Flourens succeeded in locating the vital knot more precisely, showing that it occupies an area of not more than 5 mm in the V-shaped apex of the fourth ventricle or beak of the calamus scriptorius. ("Note sur le point vital de la moelle allongee," Compt. Rend. Acad. Sci., 33:438 [1851]; "Nouveaux d6tails sur le noeud vital," ibid., 47: 803 [1858]). 50. P. Flourens, "Note touchant les effets de l'inhalation 6ther6e sur la moelle 6pini6re," Compt. Rend., 24:161 (1847). In connection with the much-publicized Bell-Magendie priority dispute, it is of interest that in this paper Flourens gave Bell credit for discovering the spinal nerve roots' functions and immediately became embroiled with a resentful compatriot, Fran4ois Magendie. 51. "Pierre Flourens," p. 300. 52. P. Flourens, "Note touchant les effets de l'inhalation 6th6ree sur la moelle allongee," and "Note touchant I'action de 1'ether sur les centr6s nerveux," Compt. Rend., 24:253, 340 (1847).

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Action Propre and Action Commune observations he concluded that anaesthesia acts first on the cerebrum, disturbing intelligence, then on the cord to extinguish sensation and movement, and finally on the vital knot to extinguish life. As had his extirpation experiments, the effects of anaesthesia confirmed Flourens' three major conclusions concerning the action propre and action commune by which the brain functions:53 1. La diversite de nos facultes a sa source dans la diversite meme des organes qui les determinent. 2. La fonction de chaque organe est propre, independent, exclusive, une. 3. [The obvious subordination of diversity to the functional unity of the whole organism arises because] Entre les phenomenes de la vie, il en est de primitifs et de secondaires; et c'est par cette subordiantion reglee que se concilient tout a la fois, dans un meme system, l'unite et l'independence. On disait, d'ailleurs, que tout a ete arrange pour que chaque partie a action distinct pCutse passer des autres . . . Ce qu'on appelle nature, n'est qu'un grand art divin. In 1842 Flourens published his Examen de la Phrenologie, a work in which he evoked the authority of his own researches and the Cartesian doctrine of the unity of the mind to prove that "Gall pretend . . . que le cerveau se partage en plusiers organes, dont chacun loge une faculte particuliere de l'ame, et il se trompait."54 In addition to the experimental and philosophical bases which we have reviewed, Flourens further rejected Gall's doctrine because "if anything, it is actually a psychology, not a physiology." Gall might have succeeded in elevating his special anatomy to the status of physiology, Flourens felt, had he performed the necessary experiments. Gall erred primarily, then, in searching for the mind's faculties, for physiology does not look for these things. Psychology studies the spirit, while physiology does not go beyond studying the brain and proper functioning of its parts.55 Flourens, in summary, cited the three errors which Gall committed by failing to confine his doctrine within the bounds of physiologic fact: 53. etudes vraies, pp. 134, 191, 286. 54. De la phrenologie, p. 25. 55. etudes vraies, pp. 186-189.

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Ii veut que la partie du cerveau dans laquelle siege l'intelligence se partage en plusiers petites organes, distinctes les uns des autres: erreur physiologique. II nie l'unite de l'intelligence, il veut que la Volonte, que la raisone, ne soient que de resultats: erreurs psychologiques; il ne voit, dans le libre arbitre qu'un determination forcee, et par consequent encore qu'un resultat: erreur moral.56 "THE NEW PHRENOLOGY" In the second quarter of the nineteenth century physiologists such as Johannes Muller relied primarily upon Flourens' account of the brain as a fairly simple organ.57 With, for example, Flourens' insistence upon the cerebrum's unitary exercise of psychic functions, there seemed no reason to study differentiation within the cerebrum itself. In 1862, five years before his death, Flourens voiced in a philosophical vein the broad motives of his own researches: "I picture to myself physiology, a probe in her hand, eagerly turning over unknown soil in order to discover there the sources of life, and to make them redound to the profit of all humanity." 58 One year prior to this statement, in the person of Paul Broca, physiology's probe had unearthed the first major challenge to Flourens' concept of action propre and action commune. As with Flourens' refutation of Gall, however, a complex current of observation and speculation had again set the pendulum in motion long before Broca's localization of the speech center in 1861. It is beyond the scope of this paper to trace the myriad details of the "new phrenology." We may note, however, that the simple Flourenian picture of the brain began to change radically from 1830 to 1850, as new techniques were developed to study the histology of the nervous system. By 1850, improvements in microscopy and tissue preparation had shown the brain to be a complex, apparently anastomosing network of cells and fibers, and workers supposed, echoing Bonnet and other sensationalists of earlier times, that the physiologic explanation of mind would be gained from further knowledge of this network. Recalling the discussion of sensationalism, it will be seen that the new histological picture of the brain neatly paralled associationism's 56. De la phTenologie, p. 33. 57. J. Muller, Physiology of the Senses, Voices, and Muscular Motion, with the Mental Faculties, trans. W. Baly (London, 1848), p. 1334. 58. "Note sur la curabilitR des blessures du cerveau," Compt. Rend. 55:69 (1862).

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Action Propre and Action Commune view of the mind as an infinitude of ideas bound together into higher mental processes through the "law of association." Paul Broca's critical discovery was made against this background of complementary biological and philosophical pictures of brain and mind. He was also following the traditions of his fellow physicians and surgeons at the Bicetre and Salpetriere who, for many years, had sought to controvert Flourens by showing a constant difference in location of brain lesions with various sensory, motor, and mental dysfunctions in their patient.59 On April 12, 1861, Broca began medical treatment of a patient, Leborgne, incarcerated at the Bicetre for thirty years solely because he could not talk. Broca's tests convinced him that Leborgne's aphasia was not due to lack of intelligence, or a muscular dysfunction in the larynx or speech organs. On April 17 Leborgne conviently died of a gangrenous infection, and autopsy revealed a lesion at the base of the third frontal convolution of his left hemisphere. In his 1861 paper, citing supporting cases, Broca concluded that Leborgne's aphasia was due not to a muscular defect but to loss of the memory for words, and that the language center is localized in the left frontal convolution.60 By 1863, recognizing that his discovery suggested the valid use of convolutions as topographical marks to localize given centers, Broca effectively attacked Flourenian doctrine: Du moment qu'il sera demonstre dans replique qu'une faculte intellectuelle reside dans un point determine des hemispheres, la doctrine de l'unite du centre nerveux intellectuel sera renversee, et il sera hautment probable, sinon tout 'a fait certain, que chaque circonvolution est affectee par des fonctions particulieres.61 Within a decade, Broca's clinically derived principle of the localization of function received support from experimental physiology's localization of sensory and motor centers. This new 59. For a good summary of studies by supporters and opponents of Flourens up to Broca's discovery, including Magendie, Desmoulins, Serres, and the tcole de la Salpetriere workers, see Soury, Dictionnaire de physiologie, pp. 617-647. 60. P. Broca, "Remarques sur la siege de la faculte du language articule suivies d'une observation d'Aphemie," Bull. Soc. Anatom., 6 (1861), 338. Broca's work, too, was the subject of priority disputes. The claimants, J. B. BouilUaud and G. Dax, maintained that in 1825 and 1836, respectively, they had located the center for articulate speech in the anterior portion of the hemispheres on the basis of clinical study of aphasia. 61. Quoted in Soury, Dictionnaire de physiologie, p. 650.

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"scientific phrenology" began with the 1870 work of Fritsch and Hitzig. Systematically placing electrodes in the dog's cerebral cortex, they found in certain anterior regions that strong stimulation produced generalized, convulsive movements. This discovery alone was highly significant, for by producing movement through electrical stimulation they overthew the generally accepted doctrine of the cortex's inexcitability, which had been fostered by workers such as Flourens and Magendie on the basis of less detailed and controlled studies. Of greater significance, for our story, was Fritsch and Hitzig's finding, in their first experiment, that stimulation with weak currents revealed localized areas controlling five separate groups of muscles. Their recognition that these motor centers, while confirming Broca's principle, are by no means as discrete as Gall's "organs", is seen in the following statement: "The muscles of the back, tail, and abdomen we have often enough exicted to contract from points lying between those marked, but no circumscribed point from which they could be individually stimulated could be satisfactorily determined." 62 By 1876, workers such as Ferrier, Nothangel, Carville, and Duret had determined more deailed maps of the motor centers.63 Meanwhile, acceptance of Muller's doctrine of specific nerve energies had instigated a search for sensory centers. In 1873, using ablation and electrical stimulation, David Ferrier received credit for first fixing the visual center in the occipito-angular region of the monkey's cortex.64 By the close of the nineteenth century two more centers had been localized-hearing in the temporal lobes and touch in the post-central region behind the motor area. Apart from its intrinsic interest, at least to those concerned with the history of the neurosciences, the development of theories of cerebral localization in the nineteenth century seems an interesting case study for the historian interested in the parameters of theory formation and acceptance or rejection in biology. 62. Quoted in David Ferrier, The Croonian Lectures on Cerebral Localization (London: Smith, Elder, and Co., 1890), p. 18. 63. See D. Ferrier, The Functions of the Brain (New York: G. Putnam, 1876). 64. With respects to Ferrier's priority, Fulton cites the forgotten clinical and experimental studies of Panizza which, in 1855, led him to conclude that the parieto-occipital area is the part of the cortex essential for vision (Physiology of the Nervous System, p. 347); D. Ferrier, "Experiments on the Brain of Monkeys," Phil. Trans., 165 (1875), 433. Ferrier's original paper on the visual center was in the West Riding Lunatic Asylum Reports, 3, 1873.

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Action Propre and Action Commune Phrenology, moreover, exemplifies a key problem of assessment in the history of science: how important, in the development of a given field of science, is a speculative theory which seems "correctly" oriented now but at the time it was promulgated lacked an experimental or even a sound experiential basis? For years after their 1808 memoir, Gall and Spurzheim strove to win acceptance for their views on the highly specific localization of psychic functions in the brain. The lay public was highly receptive to their doctrine. But scientists refused to recognize phrenology, at first on primarily philosophical grounds, and then on the basis of Flourens' evidence for action propre and action commune. In 1861, conversely, Paul Broca's colleagues quickly accepted and sought to confirm his principle of specific functional localization. The responses of the scientific community to the views of a Gall, Flourens, and Broca are readily understandable when placed in the context of their times. Given the empirical and conceptual state of the art, nineteenth-century investigators of the nervous system were particularly aware of the need to evolve sound laboratory and clinical methods on which to base study of the gross and fine structures and the functions of a subsystem such as the brain. On the question of methodology alone, it is scarcely surprising that Gall's views were at best treated cautiously by his peers. For Gall, albeit an excellent anatomist, based his functional principles upon a "special anatomy" whose essential structures-the cerebral organs-no one, himself included, could demonstrate. The cordial reception accorded Flourens' and Broca's views, in turn, was due in part to the fact that they were derived from beautifully executed laboratory experiments and from good clinical work. One must also look, as we have done too briefly, at factors such as the broader milieu of thought in which a scientific concept develops. We have seen, for example, that Flourens used, while Gall fruitlessly combatted, the widely held Cartesian concept of the unity of mind. Broca and his followers, in turn, worked toward establishing a "new phrenology" within the compatible framework provided by the psychological and philosophical views of associationism. The importance of phrenology to the development of a scientific study of the brain, as I have suggested, seems to lie preeminently in the amount of experimentation it helped to generate-mostly, as in Flourens' case, among those anxious to refute Gall's tenets. This role alone precludes us from dismissing phrenology as "merely" an amusing, quasi-scientific, popular 233

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fad (its rise and fall as a popular movement offers an absorbing study for the historian of ideas). It seems worth pointing out, finally, that the controversy over action propre versus action commune did not end with the localization of sensory and motor "centers." Beginning in 1875, the debate centered around the figures of Friedrich Goltz and Hermann Munk, who argued respectively for Flourens' views and for the precise localization of Broca and his followers. In the first quarter of the twentieth century, in turn, using the new methods of experimental animal psychology developed by Thorndike, Franz and Lashley modernized the tradition of Flourens and Goltz with their principles of mass action and equipotentiality. Then, while not accepting as precise a localization for complex functions as Broca did for language, the work of neurophysiologists such as D. 0. Hebb moved the pendulum back toward action propre. Thus, clothed in modern terms and modified by the development of new techniques, one can still see the unsettled issues between Gall and Flourens.

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ElectricityandtheNervousFluid RODERICK W. HOME Department of History and Philosophy of Science University of Melbourne, Parkville, Victoria, Australia

Throughout its history, one of the more pressing questions which physiology has sought to answer has concerned the manner in which muscular contractions are brought about. Until fairly recently the answer to this question has almost always involved recourse to "animal spirits" of one kind or another: following Galen, these spirits were supposed to flow from the brain through the nerves to the muscles, where they stimulated the contraction. Few of the theoretical modifications introduced from time to time disturbed this basic pattern of explanation; such modifications usually concerned instead either the nature of the spirits themselves, or the way in which they induced the contractions, or both. Within the traditional pattern of explanation just outlined, there remained two very different possibilities: one could regard the "animal spirits" as immaterial influences of some kind, or one could regard them as a material agency. The latter view, always widely accepted, became increasingly popular during the seventeenth and eighteenth centuries as part of the widespread acceptance of the Cartesian demand that all the phenomena of nature be explained solely in terms of motions and impacts among the particles of matter. As time passed, however, it became clear that the simple kinds of mechanism envisaged by Descartes were inadequate, and during the eighteenth century numerous branches of science compromised by introducing for explanatory purposes unexplained forces and subtle fluids of one kind or another. In the case of muscle physiology, the work of Albrecht von Haller constituted an important stage in this development. It is my purpose in this paper to investigate the rationale of Haller's discussions on the nature of the nervous fluid, and in particular to try to reach some understanding of Journal of the History of Biology, vol. 3, no. 2 (Fall 1970), pp. 235-251.

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why he dismissed out of hand the suggestion that the nervous fluid might be the same fluid as that held responsible for electrical action. Incidentally to this, I shall try to indicate the extent to which Galvani had to meet Hailer's objections when he postulated his "animal electricity" a few years later.' HALLER'SDISCUSSION OF MUSCULAR CONTRACTIONS AND THE NERVOUS FLUID Much of the early discussion of muscular contraction was vitiated by the presumption that a muscle can contract only in response to an impulse transmitted to it by the nerve. Hailer realized that muscular fibre possesses the ability to contract of its own accord, without the intervention of any nervous impulse. Accordingly, he drew a careful distinction between the properties of irritability and sensibility in muscular tissue: any part where a contraction could be observed upon stimulation he called irritable, whereas he reserved the term sensible for those parts whose stimulation caused signs of unrest (in animals) or was consciously noticed (if a human being was involved).2 From a long series of experiments, he concluded that the only parts which possess sensibility are those which are supplied with nerves, whereas irritability he found to be a property of the muscular fibres themselves.3 His distinction enabled Haller to separate the traditional problem into two parts. He could consider firstly the manner in which the nerve transmits a stimulus to the muscle (the stimulus being brought about either by an exercise of the will or by an irritation of the brain or nerve fibre), and he could then treat as a quite 1. I thus reject at the outset the critical attitude adopted by Philip C. Ritterbush in his Overtures to Biology: The Speculations of EighteenthCentury Naturalists (New Haven: Yale University Press, 1964), toward those eighteenth-century physiologists who sought to identify the nervous fluid with the electrical one. In the context of the time, and given the prevailing theories of nervous action and electricity, I regard the possibility of such an identification as a perfectly proper subject of scientiftc inquiry; the two fluids had been ascribed properties which were almost identical, and experiment had shown unequivocally that they were at least related, for electricity had been found to be remarkably effective in stimulating muscular contractions. 2. Albrecht von Haller, A Dissertation on the Sensible and Irritable Parts of Animals (Baltimore: Johns Hopkins Press, 1936; a reprint of the English edition of 1755), pp. 8-9. The term "irritability" had been introduced into physiology by Francis Glisson in his Tractatus de nlatura substantiae energetica of 1672, during a discussion of the means whereby bile is discharged into the intestines. 3. Haller, A Dissertation, p. 24.

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Electricity and Nervous Fluid separate problem the way in which the muscle responds to stimulation, whether the stimulus be transmitted via the nerve, or whether it be due to an irritant applied directly to the muscle. In this paper I shall be concerned with Haller's answer to the first of these questions. Let us note in passing, however, his answer to the second of them. Haller rejected the traditional explanation of muscular contraction in terms of elasticity, on the grounds that (i) elasticity is a property of dry fibres, and dried muscular fibres are deprived of all their irritability; (ii) "elasticity is a property of hard bodies, and irritability of the softest"; and (iii) the fibres of old subjects are more elastic than those of young ones, but they are less irritable. In addition, he repeated two of Robert Whytt's arguments: "the motion of the heart ceases and is renewed spontaneously, which is not observed in any elastic fibre, and upon pricking steel with a needle you produce no irritation in it." 4 He rejected Whytt's conclusion, however, that the soul acts to contract the fibres that are touched to prevent their being injured, his rejection being based on his distinction between irritability and sensibility; the soul he held to be active only in the case of the latter. His ultimate conclusion was that "irritability is a property of the animal gluten, the same as we acknowledge attraction and gravity to be properties of matter in general, without being able to determine the cause of them."5 In other words, he concluded that contractility is a power innate to muscle fibre, a power to which he later gave the name "vis insita," a power "found in no other part of the human body." 6 Beyond this, concerning the vis insita, we do not indeed inquire; as this seems to be a more brisk attraction of the elementary parts of the fibre by which they mutually approach each other, and produce as it were little knots in the middle of the fibre. A stimulus excites and augments this attractive force, which is 4. Ibid., p. 40. Whytt had presented his arguments in his Essay on the Vital and Other Involuntary Motions of Animals (Edinburgh, 1751). 5. Haller, A Dissertation, p. 42. 6. Haller, First Lines of Physiology, 2 vols. in one (New York: Johnson Reprint Corp., 1966; a reprint of William Cullen's translation of the third Latin edition of 1767), I, 233. The concept of irritability did not appear in the editions of 1747 and 1751, and it was not until the third edition that Haller included a reasonable account of this aspect of his work (Lester S. King, Introduction to the 1966 reprint, p. xl).

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placed in the very nature of the moving fibre. The other explanations are hypotheses. . .7 It was remarked at the outset of this paper that the Cartesian demand for mechanical explanations was widely accepted among eighteenth-century physiologists. At least four different mechanical explanations had been suggested, however, for the transmission of impulses by the nerves, and in Haller's time the issues between them had yet to be resolved. Some of these explanations in fact went beyond the traditional one based on "animal spirits" and accounted for the transmission in terms of vibrations, whether gross vibrations of the nerve as a whole, or microscopic vibrations of the particles of which it was composed,8 or vibrations of the particles of some aethereal medium supposedly pervading it,9 or some combination of these.'0 At the same time, however, more traditional kinds of explanation invoking the flow of a fluid through the nerves remained popular, being expounded most notably in the writings of Boerhaave and his pupils-amongst whom, of course, Haller is to be numbered. In the fourth volume of his Elementa physiologiae,l' and again in his First Lines of Physiology, Haller presented a number of arguments against all explanations invoking vibrations. Since the nervous fibres are not tense either in their origin or in their termination, he said, they cannot possibly vibrate. Again, in many cases they cannot vibrate because they are firmly tied to 7. Ibid., I, 236. 8. T. Morgan, Mechanical Practice of Physick, (London, 1735), pp. 145ff. 9. Isaac Newton, Opticks, or a Treatise of the Reflections, Refractions, Inflexions and Colours of Light, (New York: Dover, 1952; based on the 4th edition, London, 1730), Query 24, p. 353. Consistent with his well-known mid-career abandonment of ether hypotheses, Newton, in Query 12 in the first (1704) edition of the Opticks, spoke simply of vibrations "being propagated along the solid fibres" of the nerves, without mentioning the ether at all. The wording of this Query remained unaltered in subsequent editions, although of course an entirely new interpretation had to be put on it following the addition of what became Query 24 in 1717. It would be interesting to know what prompted Newton to extend his ether hypothesis to the action of the nerves in the way he did, but so far as I am aware this is a question which Newton scholars have not yet investigated. 10. David Hartley, for example, in his Observations on Man (London, 1749), combined the last two possibilities. Haller, in his Elementa physiologiae (IV, 358), listed a number of others besides Morgan, Newton, and Hartley who had denied the existence of a nervous fluid, but I have not checked his references to see which particular variant of the vibration theory each espoused. 11. Lausanne, 1762.

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Electricity and Nervous Fluid solid substance (here he gave as an example the fact that the nerves of the heart are tied to the great arteries). Furthermore, he argued, the nerves are totally devoid of elasticity, since when a nerve is cut in two, it neither becomes shorter, nor are the divided ends drawn back. In addition, "the extreme softness of the medulla in the brain, with all the phenomena of pain and convulsion, leaves no room to suspect any sort of tension concerned in the effects or operations produced by the nerves." Finally, he noted that muscles situated above the point of irritation are never convulsed, only those below. "This," he argued, "is a consequence altogether disagreeing with elasticity; for an elastic cord propagates its tremors every way, from the point of percussion to both extremities." 12 All of Haller's arguments except the last impinge only upon the hypothesis that the nerve vibrates like a stretched string; they do not rule out either microscopic vibrations of the particles of the nerve fibre, or ethereal vibrations along the lines suggested by Newton.'3 Far more penetrating arguments against vibratory hypotheses in general had been given already by Whytt in his Essay on the Vital and other Involuntary Motions of Animals. Whytt had argued first against both those explanations which invoked an elastic power in the nervous fibres and those which postulated oscillations of an animal spirit, on the grounds that inert matter does not possess any power of generating motion. How then, he asked, could a pinprick or a drop of acid cause the large contractions which are observed? He had also rejected the possibility of ethereal oscillations on the grounds that such oscillations must follow the ordinary laws of vibration of elastic bodies, and are hence incompatible with the observed 12. For convenience the quotations are taken from the FiTst Lines of Physiology (I, 219-220). In vol. IV of the Elementa physiologiae, the same arguments, sometimes expanded a little, appear on pp. 361-365. It is worth noting as well that several of the arguments had been given earlier by Boerhaave in his renowned Institutiones medicae (see, for example, the English translation published by W. Innys [London, 1742-46] under the title Dr. Boerhaave's Academical Lectures on the Theory of Physic (II, 310-313)). They were repeated by many other authors throughout the rest of the century. 13. Elsewhere in the Elementa physiologiae (IV, 378-379), Haller did argue against the ether hypothesis on the grounds that the ether could not be confined within the nerves. He was there concerned to argue, however, that the nervous fluid, whose existence he was by then taking for granted, was not to be identified with the ether; his argument was not designed to rule out the possibility of ether vibrations being confined in the nerves, and it certainly did not do so.

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alternate contractions and relaxations of stimulated muscle, since the latter motion has a period which decays in time. If we have reservations about the effectiveness of Haller's arguments, he certainly had none; he felt that he had shown any explanation in terms of vibrations to be untenable, and so he adopted the alternative and more traditional hypothesis of a nervous fluid: If neither the phenomena of sense nor motion can be explained from the nature of elasticity, the only probable supposition that remains is, that there is a liquor sent through the brain, which, descending from thence through the nerves, flows out to all the extreme parts of the body; the motion of which liquor, quickened by irritation, operates only according to the direction in which it flows through the nerve; so that convulsions cannot thereby ascend upwards, because of the resistance made by the fresh afflux of fluid from the brain. But the same liquid being put in motion in an organ of sense, can carry that sensation upwards to the brain; seeing it is resisted by no sensitive torrent coming from the brain in a contrary direction.14 The postulation of a fluid matter acting in the manner indicated raised a number of questions. For instance, where are the channels through which the fluid flows, and what happens to the fluid once it has arrived at the muscle? Microscopic analysis had failed to reveal any channels in the nerves, and the failure of nerve fibres to swell when a ligature was applied to them seemed contrary to expectations on any theory of fluid flow. Haller could not account for these observations; he dismissed them rather as indicating only the weakness of our senses, "but [they] have not any validity against the real existence of a juice or spirit in the nerves."15 He supposed that much of the fluid sent to the extremities was exhaled through the cutaneous nerves; he added, however, that he suspected that "a part [adheres] to the fibre; and thus it happens, that the muscles grow strong with exercise, and their brawny parts become thicker." 16 Given the existence of a nervous fluid, the manner in which that fluid actually brought about muscular contractions remained unclear; it was no more unclear, however, than the manner in which any stimulus applied directly to the muscle caused a contraction. In this regard, Haller remarked that 14. First Lines of Physiology, I, 220. 15. Ibid., p. 221. 16. Ibid., p. 243.

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Electricity and Nervous Fluid the direct manner by which the nerves excite motion in the muscles, is so obscure, that we may almost for ever despair of its discovery . . . [but] you may suppose the nervous liquor to be of a stimulating nature, by which means it forces the elementary particles of the muscular fibre to approach nearer to each other . . . That muscle then is contracted which in a given time receives more of the nervous fluid, whether that be occasioned by the will, or by some irritating cause arising in the brain, or applied to the nerve.17 He proceeded to discuss the great wastage of power in the muscles, concluding that the action of the nervous or animal fluid is very powerful . . . nor does this seem to be otherwise explicable, than by the incredible celerity by which the influx of this fluid obeys the command of the will. But how, or whence it acquires such a velocity, is not in our power to say; it is sufficient, that we know the laws of its motion are such, that a given action of the will produces a new and determinate celerity in the nervous fluid.18 What was the nature of this powerful fluid of whose existence he was convinced? Haller remarked that many held it to be "incompressible and watery, but of a lymphatic or albuminous nature." '9 This opinion he rejected, largely on account of the extreme motility the fluid had to have if it was to explain nervous action satisfactorily. "Moreover, it is very thin and invisible, and destitute of all taste and smell; yet reparable from the aliments." In particular, "it is carefully to be distinguished from that visible, viscid liquor exhaling into the intervals of the nervous chords." 20 Haller's fluid, it eventuated, was not at all like ordinary gross fluid matter. This presented no difficulty, however; the science of his day was filled with subtle fluids ranging from the phlogiston of the chemists, through the fluid of fire, responsible in one manifestation for heat and in another for light, to the pair of fluids responsible for those mysterious phenomena, electricity and magnetism. It seemed clear to Haller that the nervous fluid resembled these-that is, it was a subtle fluid. The only question remaining was whether it was identical with one of the other fluids, or whether it was instead a new and different fluid, a subtle fluid sui generis. 17. 18. 19. 20.

Ibid., Ibid., Ibid., Ibid.,

pp. 236-237. p. 240. p. 221. p. 222.

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HALLER'SREJECTION OF THE ELECTRICALFLUID In 1745, at about the same time as Haller began his researches on irritability,21 the advent of the Leyden jar had made it painfully obvious to the recipients of electrical discharges that electricity was remarkably effective as a stimulant of muscular contractions. Since the "electricians" of the time accounted for the effects they produced in terms of the excitation and transmission of a subtle electrical fluid (thought by many to be closely related to, if not identical with, Boerhaave's celebrated fluid, Fire), it was only natural that Haller should entertain the possibility that the nervous fluid was just another manifestation of the electrical one.22 Suggestions linking the two had appeared in print even before the sensational announcement of the Leyden experiment,23 and from what has been said in the previous section of this paper, it is clear that the electrical fluid could well have been the ideal substance for Haller's purposes: it was a subtle fluid; it had been shown by Watson24 to move with 21. This dating of Hailer's first researches on irritability is due to Lester S. King, "Introduction" to First Lines of Physiology. 22. In view of the persistence in the literature of statements to the contrary, it perhaps needs to be emphasized that Benjamin Franklin was not the first to introduce the notion of a subtle electrical fluid into electrical theory, for the earlier effluvialists such as Nollet and Watson had also invoked such a peculiar fluid in their attempt to account for the phenomena. Franklin's innovation was that he regarded an electrified body as one containing either more or less than its normal quota of fluid, whereas his predecessors had described the electrified state in terms of an excitation of the fluid already present. 23. Thus Motte, in his authorized translation of Newton's Principia (London, 1726; reprinted London, 1968, p. 393), had described as an "electric and elastic spirit" the ether which Newton had invoked to explain, amongst other things, how "all sensation is excited, and the members of animal bodies move at the command of the will." A few years later, Hales (Haemastaticks [London, 1733; reprinted New York, 19641, p. 59), cited some of Stephen Gray's experiments in support of the electrical theory. Then in the very paper in which he announced Musschenbroek's famous discovery to the world (Hist. l'Acad. Roy. Sci., 1746, Mem. p. 16), the abb Noilet remarked that he considered a person who drew a spark from an electrified body "comme remplie on p,enetree d'un fluide subtil, dont la r6percussion se fait sentir plus ou moins fort, plus ou moins profondement, i proportion de la grandeur du choc qu'il a regu . . . Cette commotion n'est qu'un mouvement de pression imprime a un fluide fort dlastique." Nollet's explanation of the appearance of sparks in electrical discharges was framed in the same terms; it involved a "repercussion" of two opposing streams of electrical fluid. Haller cited Hausen, Boissier, and Deshais as other early proponents of the theory (Elementa physiologiae, IV, 378); Rothschuh has given a more complete listing in his article "Von der Idee bis zum Nachweis der tierischen Elektrizitat" (Sudhoifs Archiv, 44 [1960], 25-44). 24. William Watson, Phil. Trans. Roy. Soc., 45 (1748), 76-85.

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Electricity and Nervous Fluid extreme rapidity; and it had the desired effect on muscular tissue. Yet Haller rejected the electrical fluid, claiming that the nervous fluid was something quite distinct. Why? In his First Lines of Physiology Haller mentioned only very briefly the possibility that the nervous fluid was electrical. "Many of the moderns," he remarked, "will have it to be extremely elastic, of an etherial or of an electrical matter . . . An electrical matter is, indeed, very powerful, and fit for motion." 25 To counter the suggestion he raised two objections, but he did not elaborate on them. One was that the electrical fluid "is not confinable within the nerves." Secondly, "a ligature on a nerve takes away sense and motion, but cannot stop the motion of a torrent of electrical matter." 2' These arguments were sufficient, he felt, to justify the bald assertion that "the animal spirits are not of the nature of an electric torrent." 27 As usual, Haller set out his arguments in more detail in his Elementa physiologiae.28 In this case, however, the arguments were given even more fully in papers by Felice Fontana and Marc Antoine Caldani (both written in 1757) which Haller had included in the third volume of his Memoires sur la nature sensible et irritable, des parties du corps animal.29 Fontana and Caldani had directed their arguments particularly at a M. Laghi, who had dared to make the controversial identification, and who in doing so had apparently tried to explain why, despite the electrical conductivity of the surrounding tissues, the electrical fluid could nevertheless be confined within the nerves.30 His theory was characterized by Caldani as follows: M. Laghi conjecture . . . que les electrique, que la matiere de ce l'univers, est determinee par le suc nerfs; & que les esprits electriques,

esprits sont de nature nom repandue partout nerveux 'a courir par les envelopes par le enacite

25. First Lines.. I, 221. 26. Ibid. 27. Ibid., p. 237. 28. IV, 378-380. 29. Lausanne, 1760. Henceforth referred to as Memoires. 30. Tommaso Laghi (1709-1764) was professor of medicine at Bologna at the time. I have not been able to consult any of his works, but since my concern is with the arguments against the electrical hypothesis rather than those for it, the omission should not be significant. From remarks made elsewhere by Caldani (Haller-Caldani Briefwechsel, ed. E. Hintzsche, [Bern, 19661, p. 16), it seems likely that Laghi's defense of the electrical hypothesis appeared in his Epistola responsoria ad Caesarium Pozzi (Bologna, 1756).

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du suc nerveux, ne sont arretes dans les fibres musculaires, qu'autant que celles-ci sont chaudes & flexibles.31 If Caldani's characterization is correct, Laghi's "suc nerveux" was supposed to have a rather peculiar ability to retain the electrical fluid despite its being surrounded by tissues which are electrical conductors. Caldani took Laghi to mean that the "suc nerveux" was an electrical insulator: in that case, he argued, it would simply stop the transmission of the signal along the nerve, without in any way preventing the electrical fluid from spreading into all the neighboring tissues. Fontana raised a different but equally powerful objection when he asked: Comment se peut-il qu'un muscle seul se meuve au gre de la volonte, & qu'un grand nombre de muscles ne se contractent pas en meme temps? Comment empeche-t-on que le vapeur electrique ne s'epande dans tous les muscles, qu'aborde ce nerf, plus voisins meme du cerveau?32 Much of Laghi's argument for the identity of the fluids seems to have been based on analogy, and Fontana in particular spent much time in heaping ridicule on the analogies drawn. However, both he and Caldani also produced other arguments of more lasting interest against the identification suggested. Caldani, for example, wrote: Je ne sai pas d'ailleurs, si on pourra accorder au suc nerveux la sagesse necessaire, pour mener la matiere electrique dans un nerf preferablement "aun autre: ou le pouvoir de dispenser cette matiere des loix de l'equilibre, pour lui faire enfiler un seul des nerfs, qui sortent du cerveau.33 Caldani here raised a serious difficulty. He was rather unfair, however, in using it to reject just the electrical theory. The same problem could equally well have been used to refute any other theory of nervous action. The question as to how the brain initiated impulses in a single nerve was unanswerable on any theory currently available: equally ad hoc modifications would have had to be made to Haller's fluid theory, for example, as were required in the electrical theory, before it could have provided an answer. In the passage just quoted, Caldani referred to the 'laws of equilibrium" of the electrical fluid. To understand his reference, and also to understand an argument offered by Fontana which 31. Me6moires, p. 461. 32. Ibid., p. 207. 33. Ibid., p. 463.

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Electricity and Nervous Fluid will be outlined in a moment, an appreciation of the state of electrical theory at the time is necessary. Until 1749, all theories of electricity had sought above all to explain the phenomena of electrical attraction and repulsion. They had postulated the emission of an electrical matter from electrified bodies: the most sophisticated of them, that due to Nollet, posited a double stream of electrical matter, one stream moving outward from the electrified body, the other moving inward toward it. In 1749, however, Benjamin Franklin suggested a very different type of theory:34 all matter has mixed with it a natural quantity of an electrical fluid, and bodies become electrified if they have either an excess or a deficiency of the fluid, acquiring "positive" and "negative" charges respectively in the two cases. Franklin's theory was directed particularly at explaining the phenomena associated with the Leyden jar, and also the general phenomena of conduction; it was not very adequate for explaining the traditional problems of attraction and repulsion. At no stage in his early papers, indeed, did Franklin spell out in detail his views concerning these problems, and it was not until 1755 that he tried to provide an answer in terms of static interactions between the atmospheres of electrical fluid he envisaged surrounding positively charged bodies and other atmospheres or lumps of uncharged or negatively charged matter.35 His attempt was not very successful, and in any case it came too late to prevent others, nominally adherents of his views, from attempting to explain the appearances in a semieffluvial fashion quite at variance with what he had had in mind.36 Of these the most influential was the Italian, Giambatista Beccaria, and it was upon Beccaria's exposition of the theory that Haller and his correspondents relied as they attacked Laghi's assertion that the nervous and electrical fluids were one and the same thing.37 34. Franklin's theory was expounded in a series of letters he wrote to his friends in London between 1747 and 1755 (the first detailed exposition being given in 1749). The letters were published under the general title Experiments and Observations on Electricity, Made at Philadelphia in America, the first group appearing in print in 1751. A new edition was prepared by I. Bernard Cohen, Benjamin Franklin's Experiments (Cambridge, Mass.: Harvard University Press, 1941); this is the edition I have used. 35. Benjamin Franklin's Experiments, p. 302. 36. I am currently preparing a detailed study of these aspects of Franklin's work. 37. For example, Fontana (M4moires p. 207) began his critique of Laghi as follows: "Si M. Laghi en admet l'identitW, voici ce que j'aurois a lui objecter, d'aprAs le P. Beccaria." (my emphasis).

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Beccaria began by stating his adherence to Franklin's doctrine that a body is electrified when it contains either more or less than its natural quota of the electrical fluid, and he accepted wholeheartedly the explanations Franklin had given for the behavior of the Leyden jar, and for a large number of experiments involving the sharing of charges between bodies.38 However, after carefully defining "the signs of electricity" characterizing an electrified body so as to include the attraction of light objects as well as the giving of sparks and the sensation of the electric wind, he asserted that the fundamental principle of electricity was that "All the signs of electricity are due to the vapor expanding itself from a body in which it is in a greater quantity into

one in which there is

less."39

That is, for Beccaria, electrical

attractions were due to a flow of electrical fluid.40 That this was the theory that Haller and his correspondents accepted is clear from the phraseology they chose in describing it. Fontana, for example, stated the basic idea as follows: La matiere electrique est une espece de vapeur, qui sort d'un corps, ou elle est en abondance, pour entrer dans un autre, oui il y en a moins, & elle donne des marques de ce passage, dont la force est dans la raison de la difference de la quantite de ce fluide dans ces deux corps.41 It was clearly unimportant to them which of the above attitudes one took toward the role of the electrical fluid in electrical phenomena. All that was important to them was that an electrical fluid was postulated: they were then concerned only to argue that it was not the active principle responsible for the transmission of nervous impulses. Which theory one accepted did make a difference, however, as to the sorts of arguments which could be presented to counter suggestions such as that made by Laghi. Because he accepted Beccaria's theory, Fontana was able to develop the following argument in addition to those already cited: 38. Giambatista Beccaria, Dell' elettricismo artificiale e naturale (Turin, 1753). 39. Ibid., p. 17 (my emphasis): "ogni segno elettrico avvenga pel vapore, che da un corpo, in cui e in quantit& maggiore si espande nell' altro, in cui e in minore quantit'a." 40. Beccaria was not simply reverting to the traditional effluvial theory, however: as he pointed out himself, the impact of an outward-flowing stream of matter hardly provided a straightforward mechanical explanation for the inward motion of the bodies in its path. 41. Memoires, p. 207.

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Electricity and Nervous Fluid La matiere electrique doit etre dans les nerfs & dans les muscles dans une proportion inegale, puisqu'aucun mouvement n'en resulteroit, si la quantite etoit egale: elle paroit pourtant l'etre, puisque les nerfs &les muscles sont electrifables par communication [i.e. they are conductors]. On sait que le frottement des corps de cette classe, n'ebranle pas l'equilibre de la matiere electrique, ne cause aucun torrent, & par consequent aucun mouvement.42 The last phrase in this passage provides the clue, I believe. Evidently, Laghi had interpreted muscular contractions as ordinary electrical attractions caused by a flow of electrical fluid from the nerve to the muscle. Fontana is arguing that in a system of conductors in contact, no flow of fluid can occur of a kind which can give rise to such electrical attractions; according to Beccaria's theory, attractions only occured if there was a flow of fluid across a dielectric (usually air, of course). By 1760, then, there were in print a number of powerful arguments against any identification of the electrical and nervous fluids. Let us review briefly those which have been discussed in this paper. Firstly, there is the argument that because the nerves are surrounded by electrical conductors, any electric current flowing in them will be dissipated into the surrounding tissues. Haller's argument based on ligatures of the nerves remains unanswered. There is the question of how an electrical impulse originating in the brain can be confined to a single nerve. There is Fontana's argument, just given, that an attraction giving rise to contractions can only occur if inequalities in the distribution of the fluid can be established, and they cannot be since all the tissues involved are conductors. Finally, there is the argument (implicit in Fontana's ridicule) that the analogy drawn between the electrical and nervous fluids is simply a bad analogy. These are weighty arguments. Yet in 1791 Galvani found no difficulty in explaining his experimental results in terms of an "animal electricity" flowing in the nerves. It will be our task in the next section to review the effect of developments in the intervening period on the validity of the above arguments, so as to determine the extent to which Galvani's position was a tenable one.43 42. Ibid. (my emphasis). 43. Haller's statement cited above (p. 241) that the nervous fluid is "reparable from the aliments" suggests another important difference between it and the electrical fluid. Ordinary matter and the electrical fluid were held to be independent species of being; the total quantity of each

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"ANIMALELECTRICITY" In the years between 1760 and 1791, there were two developments in particular, one in electrical theory and one in animal physiology, which are relevant to our present discussion. The change in electrical theory is the least striking of the two. Indeed, the fact that there was a change has not generally been appreciated by historians, since insufficient attention has been paid to Beccaria's work; but it was nevertheless significant, because it imposed still tighter constraints on the role which the electrical fluid could play in physiological theory. In 1756 Franz Aepinus and Johan Carl Wilcke, working together, developed an air condenser; that is, a device which was essentially a Leyden jar, but one in which the insulating layer was air rather than glass.44 As it became more and more widely known, their discovery sounded the death knell for all electrical theories which involved the emission of a fluid (including Beccaria's), and at the same time it led to the rejection of Franklin's own theory of static interactions between electrical atmospheres. The only remaining alternative, and the one which was gradually if reluctantly accepted by physicists following its formulation by Aepinus,46 was to suppose that masses of the electrical fluid exert forces on each other and on ordinary bodies at a distance-that is, forces were invoked which were no more explained than was the force of gravity. This change in the theory in no way supported Laghi's arguments-indeed, it undermined one of them even more than Fontana had done already-but it did lead to a clarification of the issues involved. Laghi, it will be recalled, had ascribed the muscular contractions to a simple "electrostatic" attraction in the universe was conserved, and one could not be converted into the other by any means. His statement that part of an animal's food intake is converted into nervous fluid suggests that Haller, like Boerhaave before him, took the latter to be simply an extremely subtle form of ordinary matter, and not an independent species of being. Elsewhere, in fact (Elementa physiologiae, IV, 381), Haller stated explicitly that while the nervous fluid was certainly extremely subtle, it was yet denser than fire or ether or electric or magnetic matter-since it could be contained in the as-yet-unobserved channels in the nervesl Possibly he was reluctant to raise arguments such as these against the electrical theory directly for fear of being accused of being too devoted to his own particular physiological "system." 44. Aepinus, MWm. Acad. Berlin (1756), pp. 119-121. For Wilcke's part in the discovery, see C. W. Oseen, Johan Carl Wilcke, ExperimentalPhysiker (Uppsala, 1939), pp. 50-51. 45. Aepinus, Tentamen theoriae electricitatis et magnetismi (St. Petersburg, 1759).

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Electricity and Nervous Fluid brought about by the flow of electrical fluid from the nerve to the muscle. According to Aepinus's theory, however, such a flow of fluid would not produce an attraction. As in Beccaria's theory, an insulating gap was required between the end of the nerve and the muscle if an electrical attraction was to occur, for only then could electricity accumulate on the end of the nerve to exert its attractive force across the intervening space. If anything, then, the new theory made it even more evident than before that the contractions were not due to electrical attractions. Henceforth, those physiologists who wished to identify the electrical with the nervous fluid had to explain the contractions in terms of a stimulation of the muscle by a current of electrical fluid flowing from the nerve; how the fluid effected this stimulation remained unexplained, as did the generation of the nerve-currents in the brain despite the fact that all the tissues involved were electrical conductors. Presumably pressure gradients were developed in the electrical fluid in the brain, but it was not at all clear how this could happen. The changes in electrical theory thus had some influence on the dispute we are considering in this paper. Much the more striking of the two developments mentioned above, however, was the discovery in the 1770's that the shock administered by the fish known as the torpedo, well known since antiquity, was just an electric shock.46 More specifically, it was shown that the fish could accumulate at will quite large quantities of electricity of opposite sign at opposite ends of the peculiar cellular structures with which they are endowed. Furthermore, Hunter's anatomical investigations showed that these structures were extraordinarily well supplied with nerves. For the electrically minded physiologist the conclusion was obvious: the cellular structures functioned as a Leyden jar, drawing charge from the nerves (which were thus seen as being analogous to the "conductor" of the electrical machine from which the more common type of Leyden jar was charged). The whole argument was no more than an analogy, of course, but it was an analogy of a particularly convincing kind, for it rested on the clear demonstration that the fish could generate electrical charges. It could not be dismissed as lightly as Fontana had dismissed Laghi's crude analogies twenty years earlier.47 46. A useful summary of the work which led to this conclusion has been given by W. Cameron Walker in his article, "Animal Electricity before Galvani," Annals of Science, 2 (1937), 84-113. 47. It was in fact sufficiently strong to convert Fontana himself to the electrical theory.

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The phenomena associated with the torpedo had other consequences for the arguments we are considering. Firstly, the torpedo provided conclusive evidence that gradients could be set up in the electrical fluid even though all the tissues involved seemed to be conductors. If this could happen in the torpedo's cells, it could also happen in the brain, and so could give rise to electrical currents in the nerves. In addition, the fact that the electrical apparatus of the torpedo was confined to a particular tissue was relevant to the argument which claimed that any electrical impulse in the nerves would be dissipated into the surrounding tissue. If the fluid could be confined to one particular tissue in the torpedo, it could be asked, why could it not also be confined to a single tissue, the nerve fibre, in other circumstances? One thing which would certainly prevent the dissipation of electrical impulses from the nerves would be an insulating sheath around them. There was, of course, no anatomical evidence for the existence of such sheaths, and it was presumably for this reason that Haller and his correspondents, Fontana and Caldani, ignored the possibility in constructing the arguments discussed earlier; Haller, however, could not find any channels to conduct his fluid, either, and this did not prevent him from assuming their existence. At any rate, Galvani, convinced already by his experiments with frogs that muscular contractions were brought about by a flow of "animal electricity," did not hesitate to postulate the existence of insulating "oily" sheaths around the nerves, and, unable to find them, he offered as a "proof" of their existence the results of a chemical distillation of nerve matter which yielded a large amount of oil.48 With this postulated, however, it became awkward to explain how contact with the outside of the nerve fibre could stimulate the muscle. To answer this, Galvani suggested that the insulating layer was very thin, so that its insulating properties could break down under appropriate circumstances. Since one such set of circumstances was the application of mechanical pressure, Galvani could have easily overcome Haller's objections based on his experimentswith ligatures, though he did not in fact do so.49 48. Luigi Galvani, Commentary on the Effects of Electricity on Muscular Motion, trans. Margarget Glover Foley; notes and introd. by I. Bernard Cohen (Norwalk, Connecticut: Burndy Library, 1953), p. 76. 49. It should be remarked that Galvani's views on the function of the nerves were rather unorthodox in ways quite unrelated to those discussed in this paper. He did not adopt the traditional view of the nervous fluid as the medium responsible for the transmission of impulses from the brain

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Electricity and Nervous Fluid CONCLUSION It may be seen, then, that if one was prepared to accept the existence of insulating sheaths on the nerves, all the arguments raised against the proposed identification of the nervous and electrical fluids, except one, could be answered satisfactorily. The single exception involved the question of how an electrical disturbance in the brain could be confined to a single nerve, and, as was indicated earlier, it was scarcely fair to hold this sort of objection against the electrical theory alone. In that case, there remained no convincing argument to show why one should not accept the identification of the two fluids. On the other hand, of course, it remained an open question as to whether there was any convincing argument to show why one should accept the identification either. Galvani thought that his experiments provided just such an argument.

to the muscles. Rather, he regarded it as something whose circulation from the inside of a muscle to the outside (or perhaps vice versa) via a nerve resulted in the muscle contracting (Commentary, p. 82). This peculiar feature of his theory does not affect the preceding argument, however, since for Galvani as for everybody else, muscular contractions were still supposed in the end to be due to the flow of a subtle fluid through the nerves, and it was this fluid which he held to be electrical in character.

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Darwinand the Physiologists, or the Medusaand ModemCardiology RICHARD D. FRENCH Visiting Research Fellow, Program in History and Philosophy of Science, 70 Washington Road, Princeton, New Jersey

Historians of biology have become aware that our understanding of the relationship between evolutionary and physiological thought in the nineteenth century seems to belie the cliche that The Origin of Species effected a revolution in all aspects of biological science. As long ago as 1925, the physiologist Pembrey, in a contribution on his speciality to the book, Evolution in the Light of Modern Knowledge, noted that "it is a matter for surprise that. . . [the effects of the Darwinian theory upon physiology] are not more obvious and definite."1 Mendelsohn, in a review article on the biological sciences in the nineteenth century has entered "a plea . . . to bring evolution back into biology and to examine the impact that evolutionary concepts had on other studies of living systems." 2 Schiller has contrasted "evolution with its synthetic view embracing a great variety of natural phenomena, the use of the species as working material, the importance of chance, the anti-teleological outlook," and "physiology with its analytical procedures, the use of the individual as working material, the deterministic explanation of each particular phenomenon excluding chance, conceived as an end in itself and devised as such by the experimental approach."3 According to Schiller, the reasons for the independent development of nine1. M. S. Pembrey, "Physiology" (Chapter VII) in Evolution in the Light of Modern Knowledge, (London, 1925), 263. Pembrey claimed nevertheless that "the effects can be traced clearly." 2. E. Mendelsohn, "The Biological Sciences in the Nineteenth Century: Some Problems and Sources," History of Science, 3 (1964), 53. 3. J. Schiller, "Physiology's Struggle for Independence in the First Half of the Nineteenth Century," History of Science, 7 (1968), 64. Journal of the History of Biology, vol. 3, no. 2 (Fall 1970), pp. 253-274.

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teenth-century physiology and an evolution-dominated biology deserve investigation.4 This paper is an attempt to clarify, by a case study, some aspects of the relationship between Darwinian thought and the researches of the rising school of scientists responsible for the rebirth of British physiology in the latter part of the nineteenth century. In 1876 Charles Darwin was the first honorary member elected to the newly formed Physiological Society of Great Britain,5 and his election was more than an act of affectionate veneration. It was the recognition of a very considerable debt to his ideas owed by founding members like Michael Foster, Walter Gaskell, George Romanes, and John Burdon Sanderson. It is an elusive debt, but one which may be profitably pursued toward an understanding of the direction in which this new school of physiologists betook itself. Darwin's botanical research utilized many physiological ideas. Darwinian thought, through published works like The Origin of Species and Insectivorous Plants (1875), and through private correspondence, in turn generated an intellectual climate which not only inspired certain areas of physiological research, but also legitimized assumptions about the evolutionary relationship between structure and function which permitted an extraordinarily fruitful cross-fertilization between apparently disparate lines of investigation. George Romanes (1848-1894) is one of the lesser known of Michael Foster's discoveries during his tenure as Praelector and later Professor of Physiology at Cambridge. Romanes graduated in 1874 and subsequently worked in University College, London, with John Burdon Sanderson. He was, as the Victorians would have it, "a man of private means," who could afford to finance 4. J. Schiller, "Evolution, Physiology, and Finality: Reflections on the Absence of Physiologists from Symposia on Evolution," The Physiologist, 2 (1959), 50-54. See also J. A. Lindsay, "Darwinism and Medicine," The Lancet (Nov. 6, 1909), p. 1329; C. L. Prosser, "Comparative Physiology in Relation to Evolutionary Theory," in Evolution After Darwin, I (1960), 569-594, esp. 569, 571; C. S. Sherrington, The Integrative Action of the Nervous System (London, 1915), pp. 235-236, 236n; J. S. Burdon Sanderson, "Elementary Problems in Physiology," Rep. Brit. Assn. Advan. Sci. (1889), p. 604; Presidential Address, ibid. (1893), pp. 13, 28. 5. E. A. Sharpey-Shafer, History of the Physiological Society during Its First Fifty Years, 1876-1926 (Supplement to J. Physiol., Cambridge, 1927), p. 13. See also E. Romanes, The Life and Letters of George John Romanes, 2nd ed. (London, 1896), pp. 50-52. Darwin, who cared much for animals, sympathized with the physiologists in their battle with the antivivisectionists. F. Darwin (ed.), The Life and Letters of Charles Darwin (London, 1887) II, 199-210; and F. Darwin and A. C. Seward (eds.), More Letters of Charles Darwin (London, 1903) II, 435-441.

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Darwin and the Physiologists his own research and contemplate it at leisure. Profoundly influenced by The Origin of Species and his personal friendship with its author (which arose through a correspondence on one of Romanes' articles in Nature) ,6 the young physiologist equipped his summer home on the Scottish coast with a marine laboratory, and determined to study the nervous system of the jellyfish.7 The existence and nature of nervous tissue in the jellyfish, or Medusa, was still an open question, despite considerable research. For Romanes, there was an evolutionary context to the investigation which gave it "unusual interest:" "nerve-tissue had been clearly shown to occur in all animals higher in the zoological scale than the Medusae, so that it was of much importance to ascertain whether or not the first occurrence of this tissue was to be met with in this class".8 The primary difficulty in detecting a nervous system seems to have been the histological intractability of the gelatinous tissue of the jellyfish swimming bell. The Medusa, or jellyfish, is a coelenterate, shaped like an umbrella. It swims by the rhythmic contraction of its swimming bell, the concave surface of which is overlaid by a uniformly thin layer of muscle tissue. Around the rim of the swimming bell is a circle of differentiated marginal tissue, consisting of a regular number of marginal bodies, or lithocysts, and their interconnecting tissue. The only previous work on jellyfish in which Romanes seems to have put any faith at all was Haeckel's description of certain nervous elements within this marginal tissue, and this account was regarded as by no means conclusive.9 6. G. S. Romanes, "Permanent Variation of Colour on Fish," Nature 8 (1873), 101. See also E. Romanes, Life and Letters, pp. 12ff. 7. "Whether George Romanes first obtained inspiration from Foster for his investigations on Medusae is less certain. The subject seems to have suggested itself to him whilst convalescing from typhoid at Nigg on the Cromarty Firth, where his family had a summer residence, and where the opportunities for such observations were considerable" E. A. SharpeySchafer, History of the Physiological Society, p. 25n. 8. G. J. Romanes, Jelly-fish Star-fish, and Sea-urchins: Being a Research on Primitive Nervous Systems (London, 1885), p. 13. 9. G. J. Romanes, "Preliminary Observations on the Locomotor System of Medusae", Phil. Trans. Roy. Soc. Lond., 166 (1876), 269-271. For previous work on jellyfish, see the above paper, and G. J. Romanes, "Concluding Observations on the Locomotor System of Medusae," Phil. Trans. Roy. Soc. Lond. 171 (1880), 198-202, and Jelly-fish, pp. 12-22. By the time the last-named was published (1885), a certain amount of reliable work done simultaneously with that of Romanes had been published, notably by the Hertwigs. For a more general survey extending back to the period under consideration, see T. H. Bullock and G. A. Horridge, Structure and Function

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If the demonstration of a histologically distinguishable nervous system was difficult, Romanes' choice of the jellyfish as experimental material was nevertheless an extremely fortunate one.10 The ability of the swimming bell to survive section and continued stimulation permitted Romanes considerable insight into various fundamentals of nervous function. I have attempted to assess Romanes' contribution to the substantive growth of neurophysiology in a previous paper." 11 Romanes' initial work on the jellyfish effectively circumvented the question of a histologically distinguishable nervous system. He made what he called the "fundamental observation:" that the excision of every ounce of marginal tissue from the rim of the swimming bell left the latter paralyzed, while the marginal tissue continued its rhythmical contraction.12 By further excision experiments, he satisfied himself that the spontaneity of the swimming bell was largely concentrated in the marginal bodies.13 These findings naturally gave rise to the question of the relationship between the muscular sheet of the swimming bell and the marginal bodies, the latter apparently being the seat of typically nervous control phenomena. Romanes found that the paralyzed swimming bell reacted to mechanical and electrical stimulation, of appropriate strength, in a manner indistinguishable from a normal contraction.14 He noted, indeed, that "when the constant current is being applied to the mutilated bell the latter often contracts in a somewhat rhythmic manner," though he could not say with certainty at this stage in his experiments, that this observation might not be an artifact. Thus far the muscular tissue of the bell had acted more or less like striated muscle;15 it apparently possessed the ability to respond to direct stimulation but lacked spontaneity. in the Nervous Systems of Invertebrates (London, 1965), I, 459-534. For histological difficulties, see ibid, 466. The reader is referred to this work in regard to substantive questions on the nervous system of the jellyfish. 10. Bullock and Horridge, ibid, I, 462; G. J. Romanes, Phil. Trans. 171 (1880), 169-170. 11. "Some Concepts of Nerve Structure and Function in Great Britain, 1875-1885: Background to Sir Charles Sherrington and the Synapse Concept," Medical History, 14 (1970), 154-165. 12. G. J. Romanes, "Locomotion of Medusidae," Nature, 11 (1875), 29. 13. G. J. Romanes, Phil. Trans. 166 (1876), 272-279. 14. "Every Medusa, when its centres of spontaneity have been removed, responds to a single stimulation by once performing that action which it would have performed in response to that stimulation had its centres of spontaneity still been intact" (Phil. Trans. 166 [1876], 281, 282). 15. Though it could not easily be made to contract tetanically. See below.

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Darwin and the Physiologists Section of the swimming bell soon demonstrated, however, that the similarity between the contractile sheet of the bell and a striated muscle was deceptive. The irritability of the bell as a whole was retained through an almost unbelievable amount of section. For example, the bell could be cut spirally producing a single strip which still responded to stimulation with a wave of contraction passing down its length. Progressive narrowing of the width of such a strip would eventually result in a wave of contraction, stimulated at one end of the strip, being unable to pass the narrow point. Romanes introduced the term "block"to signify the blockage of the wave of contraction.16 At this juncture, although his own efforts to demonstrate histologically the presence of nervous tissues in either the swimming bell or its margin had failed, Romanes decided to publish his findings. As he wrote to E. A. Schiifer in September 1875: It seems to me that the histology can very well wait for future treatment-that its absence is not sufficient justification for withholding the results I have already observed. These results after all, are the most important; for they prove that some structural modification there must* be; whether or not this modification is visible is of subordinate interest. Besides, I do not, of course, intend to abandon the microscopical part of the subject altogether. In my view, inquiry into function in this case must certainly always precede inquiry into structure. 17 The following extract from his first paper to the Royal Society (submitted in the fall of 1875 and published the following year) illustrates Romanes' conception of the questions invoved: Is the contractile tissue of the swimming-organ pervaded by a definite system of sensory and motor tracts, so to speak, radiating to and from the marginal centres? Or is the contractile tissue of the swimming-organ of a more primitive nature, the functions of nerve and muscle being more or less blended throughout its substance? Now, for my own part I deem this question the most interesting one with which the present paper is concerned; for the evolutionist, no less than the physiologist, will recognize its importance as of the highest . . . it is to the Medusae we must look for the first decided 16. Phil. Trans. 166 (1876), 288-290. Very occasionally, of contractile waves could be overcome (p. 294). 17. E. Romanes, Life and Letters, p. 37.

initial blockage

*Italics in the quotations are the original author's.

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integrations of tissue having, to say the least, something, closely resembling a nervous function to subserve; and . . . these integrations appear in the form of intensely localized centres of spontaneity. It therefore becomes a matter of pressing moment to ascertain the manner in which the spontaneous impulses are transmitted from these centres and distributed throughout the contractile tissue of the swimming-organwhether a definite system of lines of discharge becomes evolved pari passu with a definite system of centres of spontaneity, or contractile tissue can afford, so to speak, to retain more or less of its protoplasmic nature after spontaneity has become so far developed as to be localized in definite centres. Although first appearances indicated "definite lines of (nervous) discharge" to be highly unlikely, since on current models such lines of discharge would have to coincide precisely with the diverse modes of section which the organism could sustain, Romanes felt the fact that blockage of a wave of contraction in a progressively narrowed strip took place "completely and exclusively" at a single point demonstrated otherwise. He postulated "a more or less intimate plexus of . . . lines of discharge, the constituent elements of which are endowed with the capacity of vicarious action," and had a low degree of integration. It was the section of these primitively differentiated lines, "functionally, if not structurally, nerves," which resulted in a block.18 19 The question had changed, or rather developed. No longer was there a concern about presence of nerve in jellyfish. Now "the most interesting question" was a restatement of the classical biological problem of structure and function, a groping toward an evolutionary definition of nerve.20 If the so-called "differentiated lines of discharge" existed in the swimming bell in a "more or less intimate plexus" which permitted the transmission of impulses almost deviously to surmount severe section, and if no microscopical evidence for structural manifestations of these 'lines of discharge" existed, then clearly function must antecede specialized structure, perhaps as an initially invisible property 18. Phil. Trans. 166 (1876), 291-293. 19. For nerve fibers and blocks in tissue bridges, see G. A. Horridge, "An Action Potential from the Motor Nerves of the Jellyfish Aurellia aurita Lamarck," Nature 171 (Feb. 28, 1953), 400; and T. H. Bullock, and G. A. Horridge, Nervous Systems of Invertebrates I, 494. 20. For Romanes on the definition of nerve, see "Further Observations on the Locomotor System of Medusae," Phil. Trans. Roy. Soc. Lond. 167 (1877), 692, 696-697, 697n; see also Jelly-fish pp. 23-25.

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Darwin and the Physiologists of the protoplasm.21 For Romanes himself, an evolutionary solution (suitably deductive) was to be found in Herbert Spencer's Principles of Psychology.22 He had, as he said, "kept all these more or less fishy deductions out of the R. S. papers,"23 but he was not as reticent to the members of the Royal Institution, to whom he said in an evening lecture in May, 1877: Those among you who are acquainted with Mr. Herbert Spencer's writings are doubtless well aware how strong a case he makes out in favour of his theory respecting the genesis of nerves. This theory, you will remember, is that which supposes incipient conductile tissues, or rudimentary nerve fibres to be differentiated from the surrounding contractile tissues, or homogeneous protoplasm by a process of integration which is due simply to use. Thus, beginning with the case of undifferentiated protoplasm, Mr. Spencer starts from the fact that every portion of the colloidal mass is equally excitable and equally contractile. But soon after protoplasm begins to assume definite shapes recognized by us as specific forms of life . .24 When . . . a line of passage becomes fully developed, it is a nerve fibre distinguishable as such by the histologist; but before it arrives at its completed stage-i.e. before it is observable as a distinct structure-Mr. Spencer calls it a "line of discharge."25 21. "I have hitherto failed to detect any structural modifications of the tissue in the regions occupied by these supposed lines of discharge" (Phil. Trans. 166 [18761, 293). 22. H. Spencer, The Principles of Psychology, 2nd ed. (London, 1870) I, 511-521. For a somewhat later treatment of the same problem from an embryological point of view, see F. M. Balfour's address to the Department of Anatomy and Physiology of the British Association. Rep. Brit. Assn. Advanc. Sci. (1880), pp. 636-644, esp. pp. 642 and 644. See also Darwin to Balfour in More Letters of Charles Darwin II, 424-425. 23. In a letter to Darwin, August 1877. E. Romanes, Life and Letters, p. 64. 24. "Evolution of Nerves and Nervo-Systems," Proc. Roy. Instit. Gr. Brit. 8 (1879), 429. Lecture delivered May 25, 1877. 25. Ibid., 430. At the conclusion of the lecture (448n), Romanes noted that other thinkers besides Spencer had come to similar conclusions. In his later (1885) book, Jelly-fish (p. 87n), he cited Lamarck: "Dans toute action, le fluide des nerfs qui la provoque, subit un mouvement de deplacement qui y donne lieu. Or, lorsque cette action a ete plusieurs fois repetee il n'est pas douteux que le fluide que l'a execut6e, ne se soit fray6 une route, qui lui devient alors d'autant plus facile A parcounr, qu'il l'a effectivement plus souvent franchie, et qu'il n'ait lui-meme une aptitude plus grande i suivre cette route frayee, que celles qui le sont moins". The excerpt is from Lamarck, Philosophie zoologique, (1809) II, 318-319. It is slightly different

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Romanes' speculations struck an extraordinarily resonant chord in Britain in the mid-seventies. Three very separate lines of physiological research became linked, their common element being a concern with questions about the evolutionary relationship between structure and function in nervous units; this common element was generated ultimately by The Origin of Species and immediately by the correspondence and discussions taking place between Romanes, Charles Darwin, and Michael Foster. It is a truism that The Origin of Species brought the concept of the interrelatedness of living organisms and the identity of the mechanisms by which they adapt and evolve to the forefront of biological science. It was not uncharacteristic of Darwin, in particular, when in his book, Insectivorous Plants, he spoke of the "transmission of the motor impulse" and the "reflex nature of the protoplasmic aggregation" which he noted in Drosera.26 This casual transposition of animal into vegetable physiology was by no means unqualified. Nevertheless, Darwin's eagerness to demonstrate the affinities between the two was barely suppressed: "Nothing could be more striking than the appearance of the above four leaves, each with their tentacles pointing truly to the two little masses of phosphate on their discs. We might imagine that we were looking at a lowly organized animal seizing prey with its arms."27 Darwin was no more successful than Romanes in localizing the tissues through which the "motor impulse" was transmitted; in both Drosera and Dionaea he deduced that the relatively undifferentiated "cellular tissue" was involved. In Drosera, he was able to correlate the shape and orientation of these cells with "the rate and manner of diffusion of the motor impulse." 28 In Dionaea he was less successful, concluding that the impulse was transmitted more or less diffusely in all directions by the cellular tissue.29 Romanes' reaction to all this was given in his letter to Darwin of July 20, 1875: from that given by Romanes, who cites the same pages of the 1830 edition, which I have not seen. The reference was sent to Romanes by Darwin in a letter now in the possession of the American Philosophical Society. See also Life and Letters of George John Romanes, 2nd ed., p. 54. 26. C. R. Darwin, Insectivorous Plants (London, 1875), pp. 234-277, 313-318. 27. Ibid., p. 246. See also J. Schiller, "Claude Bernard et Darwin," Physis 7 (1965), 484-485, or Claude Bernard et les problUmes scientifiques de son temps (Paris, 1967), pp. 150-151; F. Darwin (ed.), Life and Letters of Charles Darwin, 3rd ed. (London, 1887), pp. 98, 320-322; and F. Darwin and A. C. Seward, (eds.), More Letters of Charles Darwin (London, 1903) I, 216; II, 266-267, 369. 28. Insectivorous Plants, 247-253. 29. Ibid., 313-318.

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Darwin and the Physiologists Your letter arrived just in time to prevent my sending an order to my bookseller for 'Insectivorous Plants', for, of course, it is needless to say that I shall highly value a copy from yourself. At first I intended to wait until I should have more time to enjoy the work but a passage in this week's 'Nature' determined me to get a copy at once. This passage was one about reflex action, and I am very anxious to see what you say about this, because in a paper I have prepared for the 'B.A.' [British Association for the Advancement of Science] on Medusae I have had occasion to insist upon the occurrence of reflex action in the case of these, notwithstanding the absence of any distinguishable system of afferent and efferent nerves. But as physiologists have been so long accustomed to associate the phenomena of reflex action with some such distinguishable system, I was afraid they might think me rather audacious in propounding the doctrine that there is such a thing as reflex action without well-defined structural channels for it to occur in. But if you have found something of the same sort in plants, of course I shall be very glad to have your authority to quote. And I think it follows deductively from the general theory of evolution that reflex action ought to be present before the lines in which it flows are sufficiently differentiated to become distinguishable as nerves.30 Darwin and Romanes had a fairly considerable correspondence on their common problems, the latter remarking, "I believe it is chiefly by comparing lines of work that in such novel phenomena truth is to be got at." 31 Romanes was not the only physiologist in communication with Darwin and influenced by him. In 1873 the Professor of Physiology at University College London, John Burdon Sanderson, inspired by Darwin's insectivorous plant research,32 and supplied with material by him,33 began a series of investigations on the 30. E. Romanes, Life and Letters, p. 34. The article referred to is A. W. Bennett, "Darwin on Carnivorous Plants," Nature 12, (1875), 206-209, 228-231. 31. E. Romanes, Life and Letters, pp. 56, 62-63, 65. Darwin and Seward More Letters of Charles Darwin, II, 51-52. See also Romanes' reference to Darwin's Drosera work in Phil. Trans. 167 (1877), 701n.-702n. 32. "I did not suggest to Sanderson his electrical experiments, though no doubt, my remarks led to his thinking of them"-Darwin to J. D. Hooker, 1874, in More Letters of Charles Darwin, II, 402. 33. Ibid., II, 395. Darwin and Burdon Sanderson's extensive correspondence on this subject is in the Darwin Collection of the University of Cambridge Library and the Sinclair Collection of the Woodward Library, University of British Columbia.

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electrical properties of plant cells which was to interest him for the rest of his career. His results with Dionaea showed, in Darwin's words, that "when leaves are irritated, the current is disturbed in the same manner as takes place during the contraction of the muscle of an animal." 34 Burdon Sanderson introduced the use of the capillary electrometer for studying electrical variations in plants and later used this apparatus to study the same phenomena in the cardiac muscular tissue of the frog.35 Darwin was also corresponding with Michael Foster regarding the use of the nerve poison urari (curare) on insectivorous plants. In an undated letter now in the University of Cambridge Library, Foster advised Darwin, "I think I am right in saying that in the absence of histologically distinct nervous elements urari seems inert-e.g. amoebae go their ways as usual in even strong solutions of it-and protoplasm generally seems to be unaffected by it."36 Foster's views on the broader theoretical issues are clear from remarks on "The Fundamental Properties of Nervous Tissues" in the second edition of his textbook, (1878): In its simplest and probably earliest form, a nerve is nothing more than a thin strand of irritable protoplasm, forming a means of vital communication between a sensitive ectodermic cell exposed to extrinsic accidents, and a muscular, highly contractile cell (or a muscular process of the same cell) buried at some distance from the surface of the body, and thus less susceptible to external influences. If in Hydra, we imagine the junction of the ectodermic muscular process with the body of its cell to be drawn out into a thin thread (as is said to be the case in some other Hydrozoa), we should have just such a primary nerve. Since there would be no need for such a means of communication to be contractile and capable of itself changing in form, but on the other hand an advantage in its 34. Insectivorous Plants, p. 318. 35. J. S. Burdon Sanderson and F. J. M. Page, "On the Mechanical Effects and on the Electrical Disturbance consequent upon Excitation of the Leaf of Dionaea muscipula," PToc. Roy. Soc. Lond. 25 (1877), 411434; "On the Time Relations of the Excitatory Process in the Ventricle of the Heart of the Frog," J. Physiol. 2 (1880), 384-435. See also F. Gotch, "Sir John Burdon Sanderson, Bart. 1828-1905," Proc. Roy. Soc. Lond. [B], 79 (1907), x-xi; F. A. Willius and T. J. Dry, A History of the Heart and the Circulation, (London, 1948), 186-187; and W. Biedermann, "Electromotive Action in Vegetable Cells," Electrophysiology, trans. F. A. Welby (London: I, 1896; II, 1898) II, 1-31. 36. University of Cambridge Library, Darwin MS 58, #141.

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Darwin and the Physiologists remaining immobile, and in its dimensions being reduced as much as possible consistent with the maintenance of irritability, the primary nerve would in the process of development lose the property of contractility in proportion as it became more irritable, i.e. more apt in the propagation of waves of

disturbance arising in the ectodermic cell.37 The concluding line of this passage cites "the valuable observations of Romanes on the movements of Hydrozoa."38 In his exposition on the spinal cord, Foster speaks of its nerve cells as composing a "functionally continuous protoplasmic network,"39 and more than echoes Spencer in his conclusion: We may infer that the protoplasmic network spoken of above is, so to speak, mapped out into nervous mechanisms by the establishment of lines of greater or less resistance, so that the disturbances in it generated by certain afferent impulses are directed into certain efferent channels. But the arrangement of these mechanisms is not a fixed or rigid one.40 This theme of inherent protoplasmic irritability is present both in Darwin, who suggested that contraction of both protoplasm and cell wall in the insectivorous plants is responsible for their movement, and in Romanes.41 42, 43 All of this somewhat elaborate background is intended to convey the intellectual atmosphere, keyed to the question of the evolutionary relationship between structure and function, which permeated the rather intimate circle of British physiologists in the mid-seventies. For Foster himself, the question was not only an interesting theoretical one requiring treatment in his textbook, but also one which had arisen earlier as having critical con37. M. Foster, A Textbook of Physiology, 2nd ed. (London, 1878), pp. 85-86. See also Foster on protoplasmic irritability in his anonymous "Animals and Plants," Quarterly Review, 126 (1869), 259-261. 38. Foster, A Textbook of Physiology, p. 86n. 39. Ibid., p. 472. 40. Ibid., p. 473. See also p. 485. 41. Insectivorous Plants, pp. 254-259. 42. PTOC. Roy. Instit. 8 (1879), 432-433. John Burdon Sanderson, in an address to the British Association in 1889, rather acidly remarked that one of the alternatives open to a physiologist who fails to find structure to correlate with function "is to fall back on that worn-out Deus ex machina, protoplasm, as if it afforded a sufficient explanation of everything which cannot be explained otherwise." Rep. Brit. Assn. Advanc. Sci. (1889), p. 607. 43. Foster, in a review of Verworn's General Physiology in 1895, alluded to his "rash youth" when he had "wild dreams of building up a new physiology by beginning with the study of the amoeba and working upwards." Quoted in A. Hughes, A History of Cytology (London, 1959), p. 142.

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sequences for his own research on the mechanism of the heart's beat. In 1859, and again ten years later, Foster had challenged the accepted view that the nerve ganglia of the sinus venosus, of the auricular septum, and at the base of the ventricle caused the rhythmic beat of the heart. His original paper, abstracted in the Report of the British Association, stated that section showed the power of beating rhythmically to be diffused through all parts of the snail's heart, and thus not dependent upon any localized mechanism.44 In 1869, he demonstrated that the application of an interrupted current to the lower two-thirds of the frog ventricle, where nervous elements could not be distinguished, nevertheless produced, "a series of beats separated from each other by distinct intervals of complete rest." Contrasting this result with the tetanus which such stimulation would produce in striated muscle, he concluded: "the cardiac muscular tissue itself differs for some reason or other from ordinary muscular tissue in a disposition towards rhythmic rather than continuous contraction; and. . . the influence of the ganglia is probably not rhythmic but continuous, whatever the exact nature of that influence be."145 In 1875,46 Foster and A. G. Dew-Smith demonstrated that stimulation of the in vitro snail's heart by single induction shock produced a characteristic, normal heart beat despite the absence of histologically distinguishable nerve ganglia or fibres and the apparent muscular homogeneity of the molluscan cardiac tissue.47 It was the ability 44. M. Foster, "On the Beat of the Snail's Heart," Rep. Brit. Assn. Advanc. Sci. (1859) Trans. of the Sections, p. 160. 45. M. Foster, "Note on the Action of the Interrupted Current on the Ventricle of the Frog's Heart," J. Anat., 3 (1869), 400-401. 46. For the background to this and subsequent work dealt with in this paper, see J. N. Langely, "Sir Michael Foster. In Memoriam," J. Physiol. 35 (1907), 234, 237, 238-239, and "Walter Holbrook Gaskell," Proc. Roy. Soc. Lond. [B], 88 (1915), xxviii-xxix; W. H. Gaskell, "The Contraction of Cardiac Muscle," in Schafer, Textbook of Physiology (London, 1900), II, 169-227. The classical researches of Stannius had generated the interest. Note the contributions of Engelmann, who in 1875 argued that, within the ventricle, the wave of contraction might be transmitted directly from one cardiac muscle cell to another. For later developments, see J. A. E. Eyster and W. J. Meek, "The Origin and Conduction of the Heart Beat," Physiol. Rev. 1 (1921), 3-43. 47. M. Foster and A. G. Dew-Smith, "On the Behaviour of the Hearts of Mollusks under the influence of Electric Currents," Proc. Roy. Soc. Lond. 23 (1875), 320-321. See also Foster and Dew-Smith, "The Effects of the Constant Current on the Heart," J. Anat. Physiol. 10 (1876), 735-771; and Foster, "Some Effects of Upas Antiar," ibid., 586-594. For Romanes' response to Foster and Dew-Smith on the heart's rhythmicity and to

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Darwin and the Physiologists of such tissue to retain physiological harmony and co-ordination which required explanation: We believe that all our knowledge of protoplasm (and we might point especially to the harnonious working of groups of cilia and ciliated cells) favors the idea of . . . a consensus among the several parts of any mass of protoplasm which acts together as a whole. Nor ought there really to be any difficulty in supposing such communications to be effected by molecular movements in the undifferentiated protoplasm; for there must be in protoplasm many kinds of currents and internal motions for which we have at present no names. We might further urge that there must be in undifferentiated protoplasm the rudiments of all the fundamental functions present in the differentiated structures in higher animals. Thus the process by which the condition of the aortic region of the snail's ventricle is communicated to the auricular region seems to be the rudiment of the muscular sense.48 In the frog's heart, where the contractile elements were far more differentiated and perhaps more isolated from one another than in the snail, Foster and Dew-Smith suggested that since rhythmicity appeared to be an intrinsic property of the muscular tissues themselves, perhaps the co-ordination function attributed to the protoplasm of the snail's heart was fulfilled by the nervous elements present in the heart of the higher animal.49 60 Thus the mid-seventies saw the conjunction of three very separate lines of research, each seeking to answer essentially physiological questions, each apparently hinging on the same question of the antecedence of function to structure in the evolution of nervous elements. The evolutionary climate of ideas generated the formulation of these questions in a theoretical context which made comparison of the three lines of research Burdon Sanderson and Page on rhythmicity of Dionoea, see Phil. Trans. 171 (1880), 187-188. 48. Foster and Dew-Smith, Proc. Roy. Soc. 23 (1875), 358; see also J. Anat. Physiol. 10 (1876), 739-741, 770-771. 49. Foster and Dew-Smith, J. Anat. Physiol. 10 (1876), 761; and Proc. Roy. Soc. 23 (1875), 339. 50. Darwin's son Francis was working in London under Foster's and E. Klein's direction during this cardiological research. See F. Darwin, "On the Structure of the Snail's Heart," J. Anat. Physiol. 10 (1876), 506-510. Young Darwin got to the crux of the problem when he said: "The anatomical relations corresponding to physiological conduction and insulation are no doubt at present obscure or unknown" (p. 510). Francis Darwin often assisted his father in botanical research.

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inevitable, despite their apparent variety. An examination of the results of the link between Romanes' jellyfish research and the cardiological research of the Cambridge school of Michael Foster and Walter Gaskell shows just how productive the comparisons thus arising were. In the first half of 1875, Foster and Romanes recognized that they were both faced, in the lower ventricle and in the jellyfish bell, with phenomena indicating the presence of nervous elements, in the absence of any histological evidence of such elements.5' Since evolution made it logical that similar structures (heart and jellyfish bell), faced with similar functional problems (rhythmic beating expelling blood and water respectively), might develop similar mechanisms to deal with these problems, the two lines of research became regarded by their investigators as mutually significant. Hence it was with Foster's results in mind that Romanes began his extensive section experiments on the jellyfish. He noted in his first Royal Society paper that electrical stimulation of the paralyzed jellyfish bell produced a form of tetanus, "not of the nature of an apparently single prolonged contraction . . . but that of a number of contractions rapidly succeeding one another -as in the heart under similar excitation." 52 It was the recognition of these gross functional affinities which came to supplant and transcend the histological basis upon which the two lines of research were originally linked. Romanes' last two Royal Society papers are filled with comparisons of the jellyfish with the heart, while the histological analogy between the two had been destroyed by the work of E. A. Schafer on the jellyfish, carried out in Romanes' summer laboratory in August 1877.53 Using gold chloride stain, Schafer was able to demonstrate the presence of distinct nerve fibers underlying the muscular sheet of the jellyfish swimming bell.54 55 Romanes was at first 51. Romanes' account of his discussions with Foster is in a letter to E. A. Schafer of June 1875. E. Romanes' Life and Letters, pp. 30-31. 52. Phil. Trans. 166 (1876), 286. 53. "Possibly the microscope may show something, and so I have asked Schafer to come down, who, as I know from experience, is what spiritualists call 'a sensitive'-I mean he can see ghosts of things where other people can't. But still, if he can make out anything in the jelly of Aurelia, I shall confess it to be the best case of clairvoyance I ever knew" (Romanes to Darwin, August 1877 in E. Romanes, Life and Letters, p. 66). 54. E. A. Schafer, "Observations on the Nervous System of Aurelia aurita," Phil. Trans. Roy. Soc. Lond. 169 (1878), 563-575. See Bullock and Horridge, Nervous Systems of Invertebrates, I, 466-473; C. Sherrington, "Sir Edward Sharpey-Schafer and his contributions to neurology," Edinburgh Med. J. n.s., 92 (August 1935), 397-398; and E. G. T. Liddell, The

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Darwin and the Physiologists cautious in accepting Schafer's results, but his last two papers utilized them fully.56 The new similarities between heart and jellyfish were based upon observations such as their common resistance to tetanus (noted above) and demonstration of "summation of stimuli" or "cstaircaseaction."57 Both lines of research seemed, in the late seventies, to be moving toward an essentially compromise solution in regard to questions of the origins of rhythmicity. In the vertebrate heart and the jellyfish, nervous ganglia present in the sinus venosus and marginal bodies respectively were thought to act as sources of the spontaneity of the heart cavities and the swimming bell. On the other hand, direct artificial stimulation of the ventricle and the paralyzed swimming bell showed that these muscular tissues possessed an inherent rhythmicity even when all connections with ganglionic tissue had been excised. The conclusion reached by Foster58 and Romanes59 was that the ganglia produce some kind of stimulation, perhaps continuous, which was transmitted by nervous structures to the muscles, whose intrinsic properties determined their rhythmic response. It is in the context of the foregoing rather crude characterization of the state of the question regarding the role of ganglia in producing rhythmic muscular action, that the cardiological researches of Walter H. Gaskell must be considered. Gaskell was a pupil of Foster's at Cambridge, who had spent the inevitable year in Germany studying under Carl Ludwig. His Discovery of Reflexes (Oxford University Press, 1960), p. 30; also, W. C. Gibson, Creative Minds in Medicine (Springfield, Ill., 1963), pp. 58-59; J. R. Baker, "The Cell Theory: A Restatement, History, and Critique. Part III: The Cell as a Morphological Unit," Quart. J. Microscop. Sci. 93 (1952), 173-174. 55. Schiifer's work, of course, required Romanes to modify his espousal of Spencer's views. See Jelly-fish, pp. 85-86. For Romanes' general ideas on the evolution of the nervous system, see his Mental Evolution in Animals (London, 1883), esp. pp. 24-33, 60, 64. 56. G. J. Romanes, Phil. Trans. 167 (1877), 664n. The response of H. Newell Martin of John Hopkins was perhaps typical: "Many thanks for the abstract of your Medusa work which you sent me. It is very important, but I feel an unscientific tendency to grieve over the loss of conductivity along special tracts not differentiated into nerve fibres: it was so nice" (Martin to Schafer, March 24, 1878, Wellcome Institute of the History of Medicine [London], Sharpey-Schafer Collection, "American Colleagues"). 57. Ibid., 685-690. 58. "It becomes necessary, therefore, to modify the hypothesis of an automatic centre in the sinus in the sense that the action of that centre is not an intermittent but a continuous one." Foster and Dew-Smith, J. Anat. Physiol. 10 (1876), 771. 59. Phil. Trans. 171 (1880), 162-189.

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approach was strongly influenced by Foster and, because of the parallel development of the two lines of investigation, by Romanes' research on the jellyfish. Charles Sherrington, who was studying under Foster and Gaskell during the period when Gaskell's research was being carried out, said many years later, The question which . . . [Romanes] put to the swimming bell and answered from it, led, it is not too much to say, to the development of modem cardiology. Medusa swims by the beat of its bell, and Romanes examining it discovered there and analyzed the two phenomena now recognized world-over in the physiology of the heart, and there spoken of as the "pace-maker" and "conduction-block". Romanes' work . . . directly inspired Gaskell's on the heart, the latter proving in its turn and in due course a stepping-stone to James Mackenzie and to Sir Thomas Lewis.60 It has been shown that the interdependence of the two lines of research owed to an evolutionary climate of ideas and was of slightly longer standing than perhaps Sherrington realized. Unquestionably, Romanes learned his basic approach and some techniques from Foster. But he was using a biological system of unique properties, and he was forced to develop appropriate concepts and techniques as his research progressed. In so doing he gained significant insights into nerve function, only a few of which are evident herein. Some of Romanes' concepts and techniques were crucial for Gaskell's demonstration of the myogenic origin and propagation of the wave of contraction which is the heart beat. In Foster's textbook of 1878, his summary of the state of knowledge as to the seat of spontaneity, or automatism, of the heart showed that the relative roles of the cardiac ganglia and the cardiac muscle in producing this automatism were as yet unclear.6' It was recognized that "no solution of the phenomena can be considered satisfactory which is not at the same time a solution, of the difficult problem, why in a normal heart beat the sequence of constituent contractions is always such as it is." 62 Gaskell's contributions to the resolution of these questions were published in two papers, in the Philosophical Transactions 60. Edinburgh Med. J., n.s. 92 (August 1935), 397. But cf. W. LangdonBrown, "W. H. Gaskell and the Cambridge Medical School," PrOC. Roy. Soc. Med. (Sect. of History of Medicine) 33 (1939), 1-12. 61. M. Foster, A Textbook of Physiology, 2nd ed. pp. 89, 143. 62. Foster and Dew-Smith, J. Anat. Physiol. 10 (1876), 759.

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Darwin and the Physiologists of 1882,63 and in the Journal of Physiology of 1883.64 The first paper was primarily significant for its methodological innovations. Gaskell introduced his suspension method for recording the beats of a frog's heart: This method enables slight variations in the force of the contractions of both auricles and ventricles to be simultaneously registered as accurately as has hitherto been accomplished for the rhythm alone. Its principle consists in the fixing of a point of the heart and registering the contractions of any two points which are separated by that fixed point, the recording being effected by means of two levers attached by silk threads to the two parts of the heart thus separated65 Gaskell was able, using this method and an adjustable clamp on the auriculo-ventricular ring, to reproduce and expand observations already made on the Continent on the phenomenon of the ventricle responding to only every second or third or more contraction of the auricle. He was able to show that progressively tightening the clamp brought about, through increased mechanical pressure on the auriculo-ventricular ring, a concomitant increase in the ratio of auricular to ventricular beats, until finally ventricular beats ceased entirely. His suspension method of recording showed that as the frequency of contraction decreased, the force of ventricular contraction increased. Hence, it was inconceivable that the excitability of the ventricular muscle had been reduced by the increased pressure of the clamp. The clamp must have produced its effect by reducing the strength of impulses coming from the motor ganglia. Further experiments involving differential treatments of contiguous tissue areas in an attempt to isolate muscular from nervous effects (such as heating the auricles and sinus without heating the ventricle, or applying poisons to the ventricle only) appeared to confirm this inference. Gaskell thus concluded that discrete impulses, arising in motor ganglia in the sinus venosus, passed from it down the heart, causing rhythmic contraction by each cavity in sequence. The rhythmicity of the isolated ventricle and the response of the 63. W. H. Gaskell, "On the Rhythm of the Heart of the Frog and on the Nature of the Action of the Vagus Nerve," Phil. Trans. Roy. Soc. Lond. 173 (1882), 993-1032. 64. W. H. Gaskell, "On the Innervation of the Heart, with Especial Reference to the Heart of the Tortoise," J. Physiol. 4 (1883), 43-127. 65. The quote is from Gaskell's second paper, J. Physiol. 4 (1883), 48. For the detailed description, see the first paper, Phil. Trans. 173 (1882), 994-995. Cf. Romanes' method, Phil. Trans. 167 (1887), 684-685, and Foster's and Dew-Smith's, J. Anat. Physiol. 10 (1876), 735.

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ventricle to every nth contraction of the auricle were epiphenomena arising from the ability of ventricular muscle to summate stimuli.66 It may be that Gaskell got the idea for the differential treatment of contiguous tissue areas from Romanes' elegant demonstration, by a similar method, of the effects of curare on the swimming bell of the jellyfish.67 Romanes' influence is much clearer and more important, however, in Gaskell's classic second paper. This paper was heralded by a rather frantic postscript appended to the previous one, stating that recent experiments had compelled him to fundamentally alter his views.68 In fact, Gaskell had begun an historic series of experiments on the tortoise and skate hearts, believing, The views held by physiologists upon many points connected with the innervation of the heart have been too exclusively based upon observations upon a single type of heart, viz. that of the frog. It is therefore very advisable to control these experiments by a corresponding elaborate series of observations upon the hearts of a large number of other animal types, and in this way to trace the evolution of function in the same way as the morphologist tracks that of structure.69 In Romanes' attempt to elucidate the possible role of nervous elements in the rhythmic beat of the swimming bell, his experiments had involved the stimulation of a progressively narrowed strip of tissue of the bell. He found that at a certain width, the tissue would inevitably be unable to further transmit the visible wave of contraction initiated by the stimulus in the wider part of the strip. Similar effects could be observed at the point in a strip of tissue to which mechanical pressure was applied.70 Occasionally successive waves of contraction might surmount these barriers.7' As noted earlier, Romanes called these hindrances to the passage of a wave of contraction "blocks."As used by Gaskell, the technique of stimulating excised strips of mus66. Phil. Trans. 173 (1882), 993-1105. 67. Phil. Trans. 166 (1876), 299-300. Bullock notes that later research on the jellyfish utilized experiments similar to Gaskell's; Bullock does not trace the concept back to Romanes, who himself was not the first to use it, though he may have arrived at it independently (Bullock and Horridge, Nervous Systems of Invertebrates, I, 503). 68. Phil. Trans. 173 (1882), 1031-1032. 69. J. Physiol. 4 (1883), 43; see also p. 48. 70. Phil. Trans. 166 (1876), 295. 71. Ibid., 294.

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Darwin and the Physiologists cular tissue and the concept of "block" became keys to a new understanding of cardiac function. Gaskell noted that in the tortoise the isolated ventricle beat as surely and steadily as the auricle. Thus their respective sources of rhythmical automatism must be of the same natureeither neurogenic and located in the ganglia of the auricle and of the upper part of the ventricle, or myogenic and diffused through the muscle of both chambers, including the lower part of the ventricle, its apex, where ganglia were absent.72 The crucial experiment was a testing of the rhythmical power of an isolated strip of cardiac muscle from the apex of the ventricle. Gaskell wrapped the strip in wire of a circuit of weak interrupted current, placed one end of the strip in contact with a second circuit of single induction shocks and recorded the contractions of the strip on a kymograph. First contractions caused by suprathreshold73 single induction shocks were weak and irregular due to the presence of a number of blocks in the muscle, each preventing the continuous passage of waves of contraction. The additions of a subthreshold interrupted current, wrapped around the entire strip, to the single induction shocks gradually broke down the blocks, until each shock produced a regular and powerful wave of contraction down the full length of the strip, and the threshold of the strip began to lower. Finally, all artificial stimulation was removed. The strip of ventricular muscle thus conditioned continued its regular rhythmical contraction, independently of artificial or nervous stimulation, for up to thirty hours.74 For Gaskell, these contractions were "clearly both myogenic and automatic." The absence of nerve ganglia and the mode of development of the contractions showed that both rhythmicity and spontaneity were properties inherent in the cardiac muscle itself, properties which allowed the muscle to be "taught to

beat."75 He concluded: Since . . . the purely myogenic rhythm of the apex is closely related to that of the ventricle and therefore . . . to that of the auricle, and since no line of demarcation can be drawn between the rhythm of the auricle and that of the sinus, the logical conclusion is that the rhythm of the sinus and therefore of the whole heart depends upon the rhythmical 72. 73. 74. 75.

J. Phlysiol. 4, (1883), 51. Gaskell did not use the term "threshold." Gaskell, J. Physiol., 4 (1883), 52. Ibid., 53.

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properties of the muscular tissue of the sinus, and not upon any special rhythmical nervous apparatus.76 Having eliminated the neurogenic origin of the heart beat, Gaskell next considered the role of nerve in transmitting the impulse, in an attempt to explain the sequential contraction of the cavities of the heart. The particular anatomy of the tortoise heart, in contrast to that of the frog, allowed Gaskell to section all the nerves passing between the sinus and the ventricle.77 He found that this "does not in the slightest degree affect the due sequence of ventricular upon auricular beat." In contrast, cutting away the auricle from the ventricle and leaving the nerve trunks intact resulted in a completely inert ventricle. From this Gaskell inferred: "The ventricle contracts in due sequence with the auricle because a wave of contraction passes along the auricular muscle and induces a ventricular contraction when it reaches the auriculo-ventricular groove." 78 Drawing again on Romanes' method of progressive section,79 Gaskell exised increasing portions of the muscular tissue of the midpart of the tortoise auricle. This produced an artificial block: just as the ventricle might respond, when the auriculo-ventricular groove was clamped, to every second auricular contraction, so too in this preparation the lower half of the auricle and the ventricle were seen to contract sequentially in response to every second contraction of the upper auricle. As the tissue bridge in the midauricle was narrowed, the ratio of upper auricle to lower auricleventricle contractions increased, until finally the latter were stilled. This artificial block produced a delay in the passage of the wave of contraction just as did the auriculo-ventricular ring in the in vivo heart. Gaskell hypothesized that the heart beat originated from a peristaltic wave of contraction passing down a tubular structure 'like that of an artery or a ureter" and evolved into its present complex arrangement of muscle fibers producing sequential contraction of the different cavities.80 "If then," he wrote, "such an alteration of conduction power occurred naturally at any point, a pause or rather an alteration of rate in the progress of the contraction would take place here of the same character as the pause between the contractions of the auricle 76. Ibid., 56. 77. "The intracardiac nerves and ganglia as they paes from the sinus to the ventricle are situated externally" (ibid., 62); see also 47. 78. Ibid., 64. For Romanes' reaction, see Jelly-fish pp. 73n-74n. 79. See Gaskell, J. Physiol. 4 (1883), 66n for reference to Romanes. 80. Ibid., 64-81. For evolution of the heart, see also 116-124.

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and the ventricle." 81 He concluded that diminished conductivity in the auriculo-ventricular groove produced there a natural block, which resulted in the pause observed. Gaskell's demonstration of the myogenic origin and transmission of the heart beat and his conception of the heart block are clear enough. The idea of the pacemaker is present in Gaskell's work, although the term itself was not introduced until the twentieth century by Sir Thomas Lewis. Romanes knew that a single marginal body, or lithocyst, could animate the entire swimming bell of the jellyfish.82 Hence, in the intact organism, one of the marginal bodies-the fastest firing one-was responsible for setting the frequency of the rhythm and was prepotent over the slower firing bodies.83 This idea of the prepotence of the fastest paced center of spontaneity was adopted by Gaskell to explain the dominance of the sinus venosus in the control of the normal heart beat, when experiments on vagal stimulation revealed centres of spontaneity in the ventricle. He concluded that an independent ventricular rhythm "remains latent, and cannot make itself apparent, because the ventricle is compelled to contract in due sequence from the more rapid contractions emanating from the sinus."84 These ideas were not, however, elaborated at any length. In the review article alluded to at the beginning of this paper, Mendelsohn asked: "Was evolution responsible for the new widespread interest in comparative investigations of the late nineteenth century?" 85 Undoubtedly it was, in the case dealt with in this paper, though here one might prefer to use the term "biological analogy" rather than comparative method, since our case developed largely independently of any self-conscious program. In retrospect, we can see that though the impact of evolution upon physiology was neither as revolutionary nor as pervasive as upon some other biological sciences, subtle but nevertheless historically interesting effects may be traced. Acknowledgements The research on which this paper is based was supported by a Research Training Scholarship (Weilcome Institute of the History of Medicine, London) and a Rhodes Scholarship. I should like to 81. Ibid., 71. 82. Phil. Trans. 166 (1876), 289-290. 83. Phil. Trans. 171 (1880), 727. See Bullock and Horridge, Nervous Systems of Invertebrates, I, 493, 503. 84. J. Physiol. 4 (1883), 86-88. 85. History of Science 3 (1964), 53.

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thank my supervisors Dr. F. N. L. Poynter, Dr. A. C. Crombie, Professor D. Whitteridge and especially Dr. J. Schiller, for their advice and assistance. Finally, I am indebted to Gerald L. Geison for his very useful criticisms and corrections.

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Lamarck,Evolution, and the Politics of Science RICHARD W. BURKHARDT, JR. Department of the History of Science Harvard University Cambridge, Massachusetts

Lamarck's evolutionary theory, briefly mentioned in a lecture in 1800 and further developed in later writings, seems to have made little impression upon Lamarck's contemporaries. Several explanations for this lack of response, in addition to the usual unhelpful statements about the time not being "ripe,"have been offered. Logically enough, these explanations for the most part have ascribed the poor reception of Lamarck's evolutionary theory to either the existence of hostile views dominating the science of the time or the insufficiency of Lamarck's own arguments and examples-or to a combination of the two. Certainly both of these factors played fundamental roles in the response to Lamarck's evolutionary theory. What has not been commented upon in any detail is the way in which Lamarck's highly personal thoughts about science and about the scientific community of his day were crucial for the way in which he presented his evolutionary views and thus, presumably, for the way in which these views were received. Lamarck looked upon the needs of science somewhat differently than did most of his younger contemporaries. Moreover, in a curious way, he displayed simultaneously an insensitivity to the difficulties others might have in accepting his novel views and a conviction that these views would indeed be poorly received. For these reasons, and possibly also because he doubted that his strength would last through all of his projected works, it appears that he did not really take great pains to present his theory in such a fashion as to compel his contemporaries to treat it seriously. He seems to have thus assured his theory of the very fate that he feared it would have. Only brief remarks on the development and structure of Lamarck's evolutionary theory will be made here. Primary attenJournal of the History of Biology, vol. 3, no. 2 (Fall 1970), pp. 275-298.

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tion will be devoted instead to Lamarck's conception of his own role as scientist, to his perception of his relations with the rest of the French scientific community, and to the effect that these views seem to have had on the way in which he presented his evolutionary ideas. In light of these considerations certain aspects of the reception of Lamarck's theory will be examined. Clearly these are not the only problems of interest in regard to the immediate fate of Lamarck's evolutionary hypothesis. Crucial to the whole question, obviously, is the problem of the strengths and the weaknesses of Lamarck's hypothesis relative to the scientific evidence available in his time. But this problem, which needs to be treated at length, will not be elaborated upon here. The scientific enterprise is a complex, multidimensional, human activityas one writer has stated, "Science stands in the region where the intellectual, the psychological and the sociological coordinate axes intersect." IThe focus of the present essay will be limited to several largely unexplored psychological and social factors relevant to the presentation and reception of Lamarck's evolutionary ideas.2 LAMARCK AND THE FRENCH SCIENTIFIC COMMUNITY The most familiar image of Lamarck is probably that of the aged, poor, and blind scientist in the last years of his life, forgotten by the vast majority of the scientists of his day and comforted only by a devoted daughter's assurances that posterity would grant him the recognition that he had not received from his contemporaries. This image is based largely upon comments made by :tienne Geoffroy Saint-Hilaire.3 Upon Lamarck's death, the sharpest critique of the scientific community that had neglected Lamarck came from the pen of Frangois-Vincent Raspail.4 Not an unbiased observer, Raspail 1. J. M. Ziman, Public Knowledge: An Essay Concerning the Social Dimension of Science (Cambridge, 1968), p. 11. 2. The author is currently completing a doctoral dissertation at Harvard University on Lamarck's evolutionary theory and its reception. 3. See especially Fragments biographiques, pr9ce'd6s d',tudes SUT la vie, les ouvrages et les doctrines de Buffon (Paris, 1838), pp. 81-82. 4. "MNcrologie; parallle," Annales des sciences d'observation, 3 (1830): 159-160. This article is not mentioned by Marcel Landrieu in Lamarck: le fondateur du transformisme (Paris, 1909), a biography which, if somewhat lacking in critical analysis, is nevertheless generally an excellent source of information. Part of the article was reproduced but unidentified as to authorship by A. Giard in his preface to "Discours d'ouverture des cours de zoologie . . . par J.-B. Lamarck," Bulletin Scientiflque de la France et de la Belgique, 40 (1907): 449. Giard, citing the original source

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Lamarck and the Politics of Science displayed a disdain for established authority (scientific as well as political) which led (or perhaps allowed) him to make observations that other men would have hesitated to put into print. Raspail's little-known article concerning Lamarck appeared in the short-lived journal that Raspail co-edited with Jacques Frederic Saigey.5 In the article Raspail contrasted the works and successes of two recently deceased scientists-Lamarck and the eminent chemist Nicolas-Louis Vauquelin. Vauquelin, like Lamarck, had been a member of the First Class of the Institut and a professor at the Museum d'Histoire naturelle. There, in Raspail's view, was where the similarities between the two men ended. Vauquelin, said Raspail, was a man who "cultivated science and fortune at the same time," while Lamarck, up every morning at five o'clock for science, "forgot fortune, and lived forgotten by power": Little suited to intrigue and to the cares [menagemens] of ambition, [Lamarck] expressed his large views boldly, without accommodating them to the tastes of the various powers that passed successively before him. He struggled against adversaries who, in becoming more powerful than he, seemed to eclipse him with the renown bestowed upon them by journalism and ministerial favors .. . Vauquelin, surrounded by flatterers and disciples, died in opulence. His fortune would have satisfied the cupidity of twenty heirs. His positions have swelled the cumuls of seven to eight scientists who divided up the spoils. Lamarck, blind and paralyzed, at his last breath felt of the passage as Lyc6e, IV, 1829, takes the passage directly from F. Picavet, Les Iciologues (Paris, 1891), p. 599. Picavet seems also to have been unaware of the identity of the author of the article. On Raspail see Dora B. Weiner, Raspail: Scientist and Reformer (New York and London, 1968). 5. Four volumes of the Annales des sciences d'observation appeared: two in 1829 and two in 1830. On the Annales see Weiner, Raspail, p. 76. Weiner notes that Raspail was "excessively prone to feeling slighted by professors and academicians" (p. 74), but she does not indicate the extent to which the Annales served as an outlet for Raspail's and Saigey's feelings about certain aspects of contemporary French science. At one point, venting their distress over the "coteries" dominating French science, they wrote: "Oh! que cette science qui a tant de charmes aux yeux de la jeunesse et des amateurs devient affligeante quand on penetre plus avant dans son sanctuaire! Vous qui la cultivez dans la retraite, croyez-nous, conservez bien toute la puret6 de vos illusions; n'approchez pas." Annales, 3 (1830), 158. De Blainvifle, Cuvier, Chevreul, and numerous other prominent scientists of the day were roughly treated in the Annales, which prove to be an interesting source for comments on the internal politics of French science in this period.

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only a few tears flow, but these were sincere and unselfish. His death is, for his two daughters, not only a sorrowful loss, but a calamity besides. He was of no use to the powers that be [le pouvoir]; how will the powers that be think of being useful to his family? Will the scientists, too busy soliciting for themselves, have enough time to awaken compassion for it? Vauquelin was replaced by M. Serullas at the Institut, and at the Museum by M. Chevreul. The first nomination honors the Institut, the second has added one sinecure more to the sinecures already in existence. The two places of M. Lamarck were solicited for while he was alive; the intrigue will not be inactive after his death.6 The above images of Lamarck and the French scientific community in 1829 are not without foundation.7 One must assume on the basis of the scientific positions that Lamarck attained during his career, however, that he had not always been divorced from the power structure of the French scientific community. Though perhaps not as adept at pursuing his own selfinterests as were certain other notable scientific figures, he was not negligent in seeking for himself a position in the official scientific structure when that structure was being reorganized during the Revolution.8 Nor did he fail in the course of his career to take an interest in various priority concerns. He displayed, as will be shown, a keen and perhaps even exaggerated sense of scientific rivalry. In 1777 Lamarck received for a proposed work on the plants of France virtually the strongest official support available-Buffon, apparently impressed by the non-Linnaean aspects of Lamarck's approach, arranged to have the work published at government expense.9 Buffon's relationships with government ministers, one 6. Annales 3, pp. 159-160. The translations from the French are the author's own. 7. For more details on the "intrigue" concerning the positions left open by Lamarck's death consult Pol Nicard, etude sur la vie et les travaux de M. Ducrotay de Blainville (Paris, 1890), pp. 105-111, and the Annales des sciences d'observation, 2 (1829), 152; 3 (1830), 305, 310-312, 469-470, 474475. 8. See Lamarck's M6moire sur les cabinets d'histoire naturelle et particuliWrement sur celui du jardin des plantes (n.d., 1790?), reproduced in Landrieu, Lamarck, pp. 42-51. 9. Correspondance relating to this matter may be found in Oeuvres complRtes de Buffon, nouvelle 6dition . . . par J.-L. Lanessan . . suivie de la correspondance . . . recueillie et annot6e par J. Nadault de Buffon (Paris, 1884-1885), 14, 356-360. Landrieu seems to have been unaware of the existence of these materials.

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Lamarck and the Politics of Science may note, tended to be excellent.") Lamarck's Flore frangoise was published in 1778."1 Shortly thereafter Lamarck was chosen (again, evidently, with Buffon's support) to fill a vacant spot in the botanical section of the Academy of Sciences. Under the circumstances this was quite extraordinary, for Lamarck had been presented by the Academy en seconde ligne behind Jean Descemet. the candidate en premiere ligne. By the decision of the king, Lamarck received the position.1" In 1781 Buffon entrusted his son to Lamarck's care and sent the two of them on an extended tour, securing for Lamarck for the purpose the title of Correspondant du Jardin et du Cabinet du Roi and giving him several scientific missions to fulfill in that capacity. Upon his return to Paris Lamarck apparently devoted most of his energies to work on the botanical section of the Encyclopedie methodique. Buffon died in 1788, but in the following year La Billarderie, the new Intendant of the Jardin du Roi, created for Lamarck the position of Gardes des Herbiers du Cabinet du Roi. The science of pre-Revolutionary France was evidently not without its politics, and these politics apparently proved on several occasions to be to Lamarck's advantage. In 1789 the Committee of Finances, named by the National Assembly, suggested for reasons of economy that the position of Garde des Herbiers at the Jardin du Roi be suppressed, and Lamarck was thus in danger of losing the place that he had only just received. In arguing that the position should not be suppressed, Lamarck maintained that it was not "one of those useless positions, created under the ancien regime for the well-being of certain favored individuals." 13 In speaking of his own qualifications as a botanist, he commented that the prospect of having to meet with the obstacles of "envy" and the "preferences" in10. See Condorcet's "tloge de M. le Comte de Buffon," Oeuvres de Condorcet (Paris, 1847), 3, 360-361. 11. Flore franmoise, 3 vols. (Paris: Imprimerie Royale, 1778). Though the title page reads 1778, the work apparently did not appear until 1779, as evidenced by the report of 1779 by Duhamel and Guettard included in the work. 12. Cuvier, who mentioned this incident in his gloge of Lamarck, remarked that Descemet "was never able to recover the place that this sort of unjust favor [passe-droit] made him miss." "tloge de M. Lamarck," Mnzoires de l'Academie Royale des Sciences de l'Institut de France, 13 (1835), viii. Landrieu, Lamarck, p. 38, has published the note from the minister to the permanent secretary of the Academy (then Condorcet) announcing the king's decision. 13. MWnzoiresur le projet du Comite' des Finances, relatif a la suppression de la place de Botaniste attach. au Cabinet d'Histoire naturelle (Paris, n.d. [1789]). In Landrieu, Lamarck, p. 36.

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volved in "intrigue" had been unable to diminish his ardor and keep him from planning a general botanical work.14 By the beginning of the Revolution, evidently, Lamarck's experience within the scientific community had given him a strong feeling that, in the midst of the pursuit of science, personal interests were frequently pursued as well. Unfortunately very little is known about Lamarck's activities during the early years of the Revolution.'5 He emerged from the tumultuous first half of the 1790s occupying a place in the First Class of the Institut and a chair at the Museum d'Histoire naturelle. The 1790s were critical years for Lamarck's professional career and for the development of his evolutionary thought. Early in the decade he considered species to be immutable. By 1800, however, he had changed his mind. During the decade, he undertook in the capacity of Professor at the Museum d'Histoire naturelle the study and teaching of a field virtually new to him-"the zoology of the insects, worms, and microscopic animals" (in short, to use Lamarck's term, the "invertebrates"). By no means, though, did he confine himself to this task. Among his other activities at this time was a long and ineffective battle that he waged against the new chemistry of Lavoisier. It was particularly in the course of this last-mentioned undertaking that he came to view the science of his time as being dominated by unphilosophical views and selfish personal interests.'6 Lamarck's confrontation with the newly formed chemical orthodoxy of his day began publicly in 1794 with the appearance 14. Considerations en faveur du chevalier de Lamarck, ancien officier au Regiment de Beaujolais, de l'Acad6mie Royale des Sciences, Botaniste du Roi, attache au Cabinet d'Histoire Naturelle (Paris, 1789). In Landrieu, Lamarck, p. 35. The projected work to which Lamarck referred was apparently the Thedtre Universel de Botanique mentioned in the Flore frangoise, I, cxviii. 15. Lamarck's connections during the most difficult days of this period were presumably rather good. By a countermanding order made on his behalf by the Comiie de Salut public (April 17, 1794) he was exempted from the act of the previous day by which he (as a member of the nobility) would have had to leave Paris. See F.-A. Aulard, Recueil des Actes du Comite de Salut public (Paris: Imprimerie nationale, 1899), XII, 640. 16. Slightly earlier, in the years that he was supposed to be Garde des Herbiers at the Jardin du Roi (1789-1793), Lamarck presumably found evidence for the view that personal interests stood in the way of his own attempts to advance the science of botany. It seems that he was not allowed by the botanists at the Jardin (Ren6 Louiche Desfontaines and Antoine-Laurent de Jussieu) to work with some of the collections there. On this subject see Edmond Perrier, "Lamarck et le transformisme actuel," Centenaire de la Fondation du Mus&um d'Histoire naturelle (Paris, 1893), pp. 479-480, or Landrieu, Lamarck, p. 52 (fn. 2).

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Lamarck and the Politics of Science of his Recherches sur les causes des principaux faits physiques.17 This work, according to Lamarck, had actually been composed some eighteen years earlier and had been presented to the Academy of Sciences in 1780.18 Busy in 1780 with botanical works, he was unable to publish his physical "researches" just then, but he took care to have the permanent secretary of the Academy affix his paraph to the manuscript in order to assure for Lamarck a date for his ideas should any problems of priority arise.9 When the work was finally published, however, no one but Lamarck seems to have felt that the ideas in question were worthy of this precaution. An explication of Lamarck's physico-chemical views cannot be undertaken here, nor is it necessary for this discussion. What is important for the present purposes is Lamarck's attitude toward the lack of response that his physico-chemical writings received. He continued the argument of the Recherches in his Refutation de la theorie pneumatique (1796), contrasting his own "pyrotic" theory of chemistry with the views of Fourcroy and the other "pneumatic" chemists. His observations on the little attention that the earlier work had received were the following: Certainly when in the important search for the laws of nature and the phenomena resulting from them a new consideration is presented to the public, reason and an interest in the truth require that it be examined and submitted to the light of discussion, in order to better appreciate its worth. But, one well suspects, the particular interest of the authors whose view this consideration contradicts can lead them to neglect the examination of it, and even to neglect as long as possible all discussion regarding it. It seems that this is what has happened since the publication of my Recherches, and it is 17. 2 vols. (Paris, Maradan). 18. Ibid., I, vii. 19. Ibid., I, viii. This was not the only time that Lamarck displayed an interest in matters of priority. On one occasion he communicated a meteorological observation to the First Class of the Institut and had the observation inserted in the proc8s verbal "pour prendre date d ce sujet." Institut de France. Acad&mie des Sciences. Proc?s verbaux des stances de l'Acad6mie. 1 (An IV-VIII, 1795-1799; published in 1910), 63. A much more significant example of a priority concern on Lamarck's part is revealed in the friction with Cuvier over who was the first to think of certain changes in the classification of the invertebrates (the most notable being the placement of the molluscs above the insects in a serial arrangement of the invertebrates). Both men made a number of comments about this dispute. See, for example, Cuvier's "Ploge de M. Lamarck," p. xxv, fn. 1, and Lamarck's Philosophie zoologique (Paris, 1809), I, 122-123.

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probable that it will always happen in similar circumstances. It is well enough known that the interest of scientists is not always in accord with the interest of the sciences.20 Like the Recherches, Lamarck's Refutation de la theorie pneumatique seemed to fall upon deaf ears. Therefore in 1796 Lamarck began presenting his physico-chemical views to the First Class of the Institut in a series of memoirs, hoping thereby to elicit a detailed discussion of his arguments. His desires were not realized. Eventually he chose not to finish the reading of the memoirs, for they seemed, he said, "to weary several of my colleagues and to be disagreeable to them." 21 He published the memoirs in 1797 under the title of Me'moires de physique et d'histoire naturelle.22 The objections that Lamarck offered to the new chemistry of Lavoisier, however misguided these objections may have seemed to Lamarck's contemporaries, had seemed to Lamarck to be the consequences of right thinking about the fundamentals on which the science of chemistry ought to be founded. Convinced of the merits of his arguments, he believed when his arguments were neglected that this neglect was the result of a conspiracy against him engineered by persons who feared that their theories (and hence their reputations) would be destroyed by his observations.23 It seems that by the early 1800's, when Lamarck 20. RWfutation de la thgorie pneumatique (Paris, 1796), pp. 2-3. 21. M,6moires de Physique d'histoire naturelle (see fn. 22), p. 410. 22. Lamarck, intending to publish these memoirs successively, as he read them to the Institut, first entitled the proposed collection M*6moires presentant les bases d'une nouvelle thgorie, physique et chimique, fond6e sur la consideration des molecules essentielles des composes, et sur celle des trois #tats principaux du feu dans la nature; servant en outre de developpement a l'ouvrage intituLW:Rgfutation de la Th.6orie pneumatique. (Paris, An V [1797]). This title page apparently appeared when the first memoir was published. The full title which Lamarck later substituted for it, and by which the collection of memoirs is generally known, is MWmoires de Physique et d'Histoire naturelle, .6tablis sur des bases de raisonnement indapendantes de toute th,eorie; avec l'exposition de nouvelles considerations sur la cause generale des dissolutions; sur la mati&re du feu; sur la couleur des corps; sur la formation des composes; sur l'origine des min,6raux; et sur l'organisation des corps vivans (Paris, An V [1797]). 23. In addition to the example cited on pp. 281-282, see Lamarck's Mtmoires de Physique et d'Histoire naturelle, p. 409 (fn.) and his Hydrog6ologie, pp. 103, 122, 159 (fn.), and 164. For comments regarding the neglect of his meteorological work, which he viewed in similar terms, consult his "Sur les variations de l'etat du ciel . . ." Journal de physique, 56 (1802), 138, his Annuaires m9t6orologiques (especially no. 9, for 1808), and his "Met6orologie," Nouveau Dictionnaire d'histoire naturelle, 20 (ParisD1terville, 1818), 474-477.

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Lamarck and the Politics of Science first began to make his evolutionary ideas known, he had come to expect little favorable reaction, indeed little reaction at all, to the various ideas he was expressing.24 In his Recherches sur l'organisation des corps vivans, from which his better known Philosophie zoologique developed, he wrote: I am well aware that now few people will take interest in what I am going to set forth, and that among those who may peruse this book, the majority will claim to find here only systems, only vague opinions, by no means founded upon exact knowledge. They will say it; they will not write it.25 One can safely doubt that the major French chemists at the end of the eighteenth century felt threatened by Lamarck's ideas and thus actively conspired against him. Busy with their own researches, which were proving to be quite profitable, they had little reason to display any sort of intellectual sympathy for the framework Lamarck was proposing, which, despite Lamarck's claims for its significance and novelty, must have struck them as inappropriate and outmoded. One wonders, however, how they did respond, or managed not to respond, to the chemical and physical memoirs that Lamarck read at the meetings of the Institut. Lamarck's published comments alluding to the repression of his ideas are for the most part not very specific. In a remarkable unpublished sketch, however, he not only displayed the rancor that his unsuccessful struggles had left with him, but he also gave a fairly explicit description of the methods by which he believed the neglect of his ideas was being brought about: il s'agit dis-je de verser dans les societes particuli'eres en profitant des occasions que l'on fait naltre, le ridicule et le mepris sur l'individu qui a l'audace de ne pas croire ce qu'on fait accroire si facilement a tout le monde. Il y a pour cela un art qui est fort perfectionne dans les grandes villes. On n'a point la maladresse de declamer longuement et avec chaleur contre l'individu; on se feroit soupgonner de prevention, de jalousie, 24. After 1802, in fact, Lamarck did not deliver any memoirs of his own at the Institut. The reason for this is not altogether clear, but may in part have been due to the fact that the last memoir he delivered at the Institut was not only commented upon but in fact severely criticized (by Laplace). The memoir was Lamarck's "Memoire sur les variations de l1'tat du ciel," published in the Journal de physique, 56 (1802), 114-138. The incident is referred to in a letter from Etienne Geoffroy Saint-Hilaire to Cuvier, Institut de France (Fonds Cuvier), MS 3225 (12). 25. (Paris, 1802), p. 69.

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&c. &c. Mais avec quelques monosyllabes employes a propos, un sourir meme et un clein d'oeil, un air de dedain, passant promptement a autre chose, on produit tout l'effet desire. Et si paraventure quelque question par un homme sans finesse etoit faite a cet egard; deux mots suffisent en reponse: celui dont on parle c'est un homme qui ne sgait rien, qui ne connois pas les faits; qui n'a jamais fait d'experience. Ainsi un certain nombre de suppots du grande oeuvre, repandus dans tous les coins de la societe n'attaquant jamais ouvertement l'ennemi commun, mais le ruinant partout dans l'obscurite, ne lui laissent aucun moyen de deffense. De cette maniere ils previennent tout ebranlemant du bel edifice qu'ils concourent a maintenir.26 One suspects that although there is probably considerable distortion in Lamarck's view of the personal motives involved in the neglect of his physico-chemical ideas, there is probably still a good deal of truth in the general picture presented above. Potential contributions to science may be judged tacitly and may never receive a public hearing.27 A scientist and his work may be discredited by means of innuendo rather than through open confrontation. Such mechanisms seem to have been operating in respect to Lamarck's evolutionary ideas. Before examining some aspects of the reception of Lamarck's evolutionary ideas, some elaboration upon Lamarck's conception of his role as scientist is in order. LAMARCKAS NATURALISTE PHILOSOPHE From Lamarck's writings one can get a fairly good sense of what he considered his role as scientist to be-that of a man with the powers of meditation and the breadth of vision neces26. Mus6um national d'Histoire naturelle, MS 756, ler cahier, p. 11. The passage is from a discourse apparently originally intended as an introduction to Lamarck's Hydrog6ologie, the manuscript of which bears the title Physique terrestre. The discourse is entitled "Discours contenant une discussion critique sur les th6ories physiques en general, sur celles maintenant etablies, sur les moyens pris pour les maintenir, enfin sur les difficultes d'operer des rectifications dans les 6carts otd l'on s'est jette." The manuscript of the discourse is incomplete. For the passage cited here, minor abbreviations in the manuscript have been replaced by the full words. Lamarck's spellings have been preserved. In the manuscript Lamarck wrote "proneurs" above "supp6ts" and "6difice" above "oeuvre" (line 15 of the above passage). 27. See the interesting observations by Michael Polanyi, "The Growth of Science in Society," Minerva, 5 (1967), 533-545.

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Lamarck and the Politics of Science sary to give to science the rational foundations and the direction that it needed. The role seems to have become clarified in his mind in the 1790s as he criticized at length the new chemistry of Lavoisier and as he struggled against what he considered to be an over-emphasis in contemporary science upon the importance of facts and facts alone. By 1800 he had a name for the performer of this role-the Naturaliste philosophe.28 It was in the spirit of the Naturaliste philosophe, the naturalistphilosopher, that Lamarck attacked the chemistry of Lavoisier, projected the broad undertaking that was to be his "terrestrial physics," and conceived his theory of evolution. The manuscript version of the introduction to Lamarck's Hydrogeologie is instructive in presenting Lamarck's view of the progress of scientific methodology up to the beginning of the nineteenth century: Dans les sciences physiques, on s'est d'abord trop presse d'etablir des theories sur chacune des parties de ces sciences; en sorte qu'on a ete contraint de se passer de la connoissance d'une multitude de faits dont la consideration neanmoins est essentielle pour decouvrir les veritables loix de la nature. Ce tort, contre lequel des personnes sages se sont elevees avec beaucoup de raison, a ete a la fin remplace par un autre, qui est tout aussi nuisible 'al'avancement de nos connoissances physiques que le premier, et qui lui est entirerement oppose. II semble qu'un penchant naturel, entraine toujours l'homme vers un exces quelconque, et l'empeche, dans tout, de saisir le seul point convenable a l'objet. En effet, c'est a present un merite fort estime que de ne s'occuper qu'a recueillir des faits. On doit en rechercher de toutes parts; on doit les considerer tous isolement; enfin on doit se circonscrira partout dans les plus petits details; cette marche seule, dit-on, est estimable. Pour moi je pense qu'il peut etre maintenant utile de rassembler les faits recueillis, et de s'efforcer 'a les considerer 28. The phrase was used by Lamarck in the introductory lecture to his course at the Museum in 1800 and appeared in print in his SystWme des animaux sans vertebres (Paris, 1801), p. 11. Lamarck does not define the phrase, nor does he use it to the exclusion of similar phrases. The phrase does seem to be especially useful in describing him, however, for it suggests the important meditative element involved in his approach to the study of nature. One may note an interesting connection between Lamarck's ideas about the importance of the habit of meditation and his notion of the effects of use and disuse: he observes that of all the organs of man's body, the brain-the "organ of thought"-is most affected by exercise (Rech. org. corps vivans, p. 126).

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dans leur ensemble, afin d'en obtenir les resultats genenraux les plus probables. Celui qui conclueroit que dans l'etude de la nature, nous devons toujours nous borner a amasser des faits; ressembleroit 'a un architecte qui conseilleroit toujours de tailler des pierres, de preparer des mortiers, des bois, des ferrures, &c. et qui n'oseroit jamais employer ces materiaux pour construire un edifice.29 Lamarck was not afraid to build an edifice. As Naturaliste philosophe he aspired to see things whole, and he refused to restrict his science to problems that he considered to be of secondary interest and importance. He did not deny the importance of facts, nor did he fail to agree that "system-building" in science tended only to be wasted effort. But, as he asked rhetorically in his Hydrogeologie, what must one then do with such questions as whether or not the beds of the oceans had changed in the course of the earth's history? . . . are we reduced to being able to form only arbitrary hypotheses, only gratuitous assumptions on these basic subjects, and, as many now think, must we avoid, under the pretext of this danger, envisaging the most important questions, only to occupy ourselves with the consideration of those of an inferior order, only to gather without end all the small facts that appear, and only to study them in isolation down to the most minute details without ever trying to discover the general facts or those of the first order, of which the others are only the last results?30 Lamarck was interested in "facts", but his facts were what he called grands faits, not petits faits; facts of the first order of imnportance,not of the second order of importance.3' As he posed the above question he was in the midst of working on his 29. Museum national d'Histoire naturelle, MS 756, ier cahier, p. 3. 30. Hydroge'ologie (Paris, An X [18021), pp. 5-6. Three years later Lamarck introduced his hypothesis of geological change in the following terms: "Perhaps it will be said that it would be wiser to be silent tin regard to a number of geological facts] than to offer some supposition that one would not know how to prove, even if it had some likelihood. I do not think so, and I believe that the course of silence is good for nothing. Every effort to lift the veil which hides nature's operations from us is useful; a mediocre idea often gives birth to a better one, and by force of trying one will perhaps obtain some successes. All that is important in such circumstances is to give as certain only that which is clearly demonstrated." "Considerations sur quelques faits applicables A la theorie du globe." Annales du Mus6um d'Histoire naturelle, 6 (1805), 38-39. 31. Hydrog6ologie, p. 7.

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Lamarck and the Politics of Science Physique terrestre, which was to encompass "considerations of the first order" relative to the earth's atmosphere (meteorology), to the earth's crust (hydrogeology), and to living organisms (biology).32

LAMARCK'SPRESENTATION OF HIS EVOLUTIONARYIDEAS Lamarck's appraisal of the way his ideas would be treated by his contemporaries, his desire to deal with problems of the first magnitude, and his fear that failing health would prevent him from completing all of his projected researches combined to influence the way in which he presented his evolutionary theory. These factors display themselves in the section entitled "motives for this work" introducing his Recherches sur l'organisation des corps vivans. The Recherches originated, Lamarck said, when he decided to publish the opening discourse of his course for 1802 so that the ideas expressed in it would not be misrepresented. Having intended at first to publish just the discourse, he "soon felt the necessity of adding some developments to it in order to be better understood." The book was written rapidly.33 Materials that Lamarck had intended to use in his Biologie were employed, for he feared that his health might not permit him to finish the Biologie after he finished his Meteorologie, which he planned to publish first.34 Lamarck's comments on the reception that he expected for his ideas are extremely interesting: I am well aware that the novelty of the considerations exposed in this work and especially their extreme dissimilarity with what is commonly thought in these matters call for a more extensive treatment in order that the base of the considerations in question be better founded and more easily perceived. Despite that, I have said enough about them so that the small number of those to whom I address these Recherches may be in a position to understand me and to recognize what is justified. There is, indeed, enough knowledge 32. Ibid., p. 8. 33. Lamarck says he wrote the book rapidly but does not indicate just how much time the writing took. The time from the delivery of the discourse (27 floreal an 10) to when he delivered a copy of the published book to the Institut (9 thermidor an 10) was slightly less than two and a half months. It is not entirely clear from what Lamarck says, however, whether he began work on the book before or after he delivered the discourse. 34. Pages v-vi.

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spread among the men who have seriously occupied themselves with the observation of nature, so that each of them can easily supply the details and all the applications that are missing here. I am furthermore aware that even if I were to give to this writing the dimensions that its object calls for, there are, considering the present state of science, many reasons standing in the way of my principles being or rather appearing to be appreciated by those who ought to be the natural judges of them. I have acquired much experience in this regard, so that I know almost in advance what for the present must result from my efforts to make known some important truths that I have succeeded in discovering. My goal, nevertheless, will be completely fulfilled as soon as I have recorded them.35 Lamarck's feelings about personal motives influencing the response to his ideas have been seen in some of his earlier writings. What is particularly striking about the above passage is Lamarck's apparent lack of concern relative to convincing the prominent scientists of his day of the validity of his views. He seems to have been interested in making known his ideas, but rather less inclined to worry about trying to prove them to those disinclined to appreciate them in the first place.36 Those who were sympathetic with his observations were to be left with the task of verifying them. This, one must suppose, was a highly inopportune moment in Lamarck's career for him to adopt such a posture. Undoubtedly somewhat discredited in the eyes of his contemporaries by his physico-chemical speculations and, it seems, by his meteorological researches as well, Lamarck was in no position to tackle the fundamental problems of biology in an apparently speculative fashion and hope that his thoughts would be considered attentively. It should be remarked at this point that beyond his oftenverbalized awareness that new ideas tend to catch on slowly, Lamarck seems to have been singularly insensitive to the specific difficulties others might have in accepting his views. Though 35. Ibid., pp. vi-viii. 36. This approach seems to have been fully as characteristic of Lamarck's actual behavior as the other approach that he suggested (see below, p. 297). Lamarck's ambivalence on this matter, indicated by his numerous attempts to promulgate his views, suggests how much he cared about his ideas but how incapable he was of advancing them in a way that would impress his contemporaries and how frustrated he was from his earlier unsuccessful intellectual ventures.

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Lamarck and the Politics of Science Ducrotay de Blainville's Histoire des sciences de l'organisation is not uniformly reliable, the following comment made there about the difficulty of impressing Lamarck with a criticism is probably an apt one: . . . it must be admitted that it was scarcely with the intention of enlightening himself that [Lamarck] entertained discussion. Indeed he listened very little, and instead of responding to objections, he would enter again into the exposition of his doctrines. IR e'tait lui-meme et ne pouvait rien recevoir d'ailleurs.37 Indeed, neither criticism, ridicule, nor neglect could shake Lamarck's confidence in the merits of his own ideas. In the Philosophie zoologique he wrote "the facts I am stating are very numerous and positive, and the consequences I have deduced from them have appeared to me to be just and necessary, so that I am persuaded that only with difficulty will they be replaced by better ones." 38 On a more modest note, on the basis of an argument that only observed facts and not the consequences drawn from them, could be counted on as true, he provided the following statement concerning what he was presenting: . . . the thoughts, the reasoning, and the explanations set forth in this work ought to be considered as mere opinions which I am proposing for the purpose of indicating what seems to me to be, and what may actually take place.39 That was not to say, however, that he had given up hope of influencing the science of his time: In publishing these observations, with the results that I have deduced from them, my purpose is to invite enlightened men who love the study of nature to follow them and to verify them, and to draw from them on their own part the consequences that they consider appropriate.40 A similar expression of intent may be found in the avertissement to the Histoire naturelle des animaux sans vertebres (1815). There Lamarck also added the plea that his work be examined in the same spirit in which it was written, 'because 37. Henri-Marie Ducrotay de Blainville, Histoire des sciences de l'oTganisation et de leurs progrTs comme base de la philosophie, redigee etc. par. F.-L. M. Maupied (Paris, 1845), III, 358. 38. Philosophie zoologique (Paris, 1809), I, xviii. 39. Ibid., I, xxiii. 40. Ibid.

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in examining it with an opposite or prejudiced frame of mind, the best established considerations, even the clearest truths, will only seem to be errors."41' By 1815, however, this plea was probably too late. Lamarck's various presentations of his evolutionary theorythe most notable being in several introductory lectures for his course at the Museum, in the Recherches sur l'organisation des corps vivans, in the Philosophie zoologique, and in the introduction to the Histoire naturelle des animaux sans vertebresdisplay successive refinements in the interrelation of their parts. In the earliest presentation (1800), an introductory lecture on the importance of the study of the invetebrates, Lamarck stated that beginning with the simplest animals, and through time and favorable circumstances, nature had brought all her productions into existence.42 Changes in an animal's way of life, Lamarck said, affect the animal's structure, and the structural changes thus acquired are passed on to succeeding generations. In this presentation Lamarck already had some examples of such changes to offer: the web-footing of water birds, the claws of perching birds, and the elongated legs of wading birds were presented as the results of the accumulated effects of the influence of habit upon structure. Denying the existence of a linear series of species or genera, Lamarck maintained that a series of graduated complexity did exist between the "principal masses, such as the large families" of animals. Species and genera were to be looked upon as lateral ramifications from the general series. Lamarck gradually assembled his ideas of 1800 into a coherent theory. By 1809 in his Philosophie zoologique the theory had taken on a rather definite framework based on two factors: the inheritance of acquired characteristics, used to explain the lateral ramifications from the general series; and "the cause which continually tends to make organization more complex," responsible for the general series itself. By 1815 in his Histoire naturelle des animaux sans vertebres Lamarck felt able to say that "on the source of existence, of the manner of being, of the faculties, of the variations, and of the phenomena of organization of the different animals" he had presented "a truly general theory, linked everywhere in its parts, always consistent in its principles, and applicable to all the known data." 43 41. Pages iii-iv. 42. "Discours d'ouverture, prononce le 21 floreal an 8 [May 11, 1800]," Systeme des animaux sans vertebres (Paris: Deterville, 1801), pp. 1-48. 43. Pages iii-iv. Lamarck's preference for presenting theories in a

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Lamarck and the Politics of Science Lamarck also suggested in the Histoire naturelle that in presenting the essential facts relative to the organization and the resultant faculties of the various invertebrates he would be providing the pie'ces justificatives of the ideas published in the Philosophie zoologique and further developed in the Histoire naturelle. Despite this insistence on the factual basis of his theory, however, he never carefully showed the way in which his facts and his theory were related. The successive presentations of his theory were not so much attempts to persuade readers of the theory's validity as they were simple expositions of the theory itself. Lamarck, it seems, was not especially concerned about the details. It does not appear that he worried over his examples of evolutionary change, and he may well have been surprised, despite his claims of awareness of his contemporaries' interest in facts, to find that his examples of evolutionary change attracted more attention than did the general arguments of his work.44 Perhaps because of the unfavorable response to these examples he omitted them from the final presentation of his evolutionary views. His theory continued to be associated, much to his disadvantage, with such examples as that of the giraffe gaining its long neck and forelegs through the efforts of successive generations of giraffes stretching to reach the leaves above them. THE RECEPTION OF LAMARCK'SEVOLUTIONARYIDEAS: THE ROLE OF CUVIER With the exception of a few brief and scattered comments Lamarck's evolutionary ideas were publicly received in silence. deductive form is explicitly stated in a manuscript entitled "La Biologie", which has been published by Pierre-P. Grass6, Rev. Sci., 5 (1944), 267-276 (see p. 271). Despite this preference, Lamarck indicates in the manuscript (believed to have been written between 1809 and 1815) his intention to write a major work (La Biologie) which would begin with an exposition of facts rather than general principles for the very purpose of convincing his contemporaries of the validity of his views. The work was never executed, and the form of the introduction to the Histoire naturelle of 1815 was not appreciably different from Lamarck's earlier writings. 44. There is a strong parallel here between Lamarck's biological writings and his meteorological writings. Looking back in his eleventh and final Annuaire meteorologique (pour I'an 1810) on the Annuaires he had published for more than a decade, Lamarck admitted a strategic error on his part in not treating the probabilities given in the Annuaires seriously enough: "I perhaps greatly wronged the study that I wanted to encourage, supposing incorrectly that more attention would be paid to the observations recorded in the different numbers of the Annuaire than to the probabilities presented there" (p. 167).

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Attention will be paid here to the posture toward Lamarck's ideas adopted by the dominant figure of French natural science at the time: Georges Cuvier. Georges Cuvier's magisterial and disapproving presence has long been recognized as a factor in the poor reception of Lamarck's evolutionary theory by his contemporaries. Cuvier's reasons for opposing the hypothesis of species mutability have been dealt with at length elsewhere and do not need to be repeated here.45 Primary concern here will be with the way in which he treated Lamarck's views. It is not likely that Lamarck's physico-chemical views were neglected for reasons of jealousy, as Lamarck had assumed, and the same can be said of the treatment of his evolutionary views. This does not mean, however, that these views were not methodically neglected. Consider the following statement written by Cuvier in 1806, setting forth his view of what scientific bodies had to do to assure for the science of geology the growth of which that science was capable: [Scientific bodies] must maintain in [geology's] regard the conduct that they have maintained since their establishment in regard to all the other sciences: To encourage with their eulogies those who report positive facts, and to retain an absolute silence over the systems which succeed to one another.46 One may well presume that the "absolute silence" recommended for "systems" was the very antidote that had first been applied to Lamarck's chemical theories and was later applied to his zoological theories. To Cuvier, evidently, Lamarck's chemical and zoological theories both appeared as "vast edifices [constructed] on imaginery bases," and thus both deserved the same treatment. In his Eloge of Lamarck Cuvier wrote: . . .whatever interest [Lamarck's zoological works] may have excited by their positive parts, no one believed their systematic part dangerous enough to merit being attacked; it was left in the same peace as the chemical theory.47 One may suppose that Cuvier's use of the words "dangerous 45. William Coleman, Georges Cuvier, Zoologist: A Study in the History of Evolution Theory (Cambridge, Mass.: Harvard University Press, 1964). 46. "Rapport de l'Institut national . . . sur un ouvrage de M. Andr, ayant pour titre: Theorie de la surface actuelle de la terre," Journal des mines, 21 (1807), 421. 47. "tloge de Lamarck," (see fn. 12 above), p. ii.

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Lamarck and the Politics of Science enough to merit being attacked" instead of some equivalent of "reasonable enough to merit being considered" is not without significance. One may also remark that, in the statement that Lamarck's zoological speculations were "left in the same peace as the chemical theory," the word "peace" should probably be interpreted strictly as the public silence that Cuvier recommended for all "systems." Certainly the picture that ?tienne Geoffroy Saint-Hilaire painted of the last years of Lamarck's life was not one of peaceful neglect. In Geoffroy's words, "attacked on all sides, insulted even by odious jests, Lamarck, too indignant to respond to such cutting epigrams, submitted to the insult from them with a sorrowful patience." 48 Geoffroy Saint-Hilaire was a friend of Lamarck, and he himself adopted the general theory that modern species have descended from primitive forms, but these are not reasons to doubt the validity of his statement. In an unpublished manuscript one finds Cuvier writing about Lamarck: "In truth his explanations are sometimes very amusing despite the admiration that some naturalists pretend to show for them."49 In another work, published posthumously, Cuvier's comment on authors who had favored the idea of species transformation was: "From the moment that these authors wished to enter into detail they fell into ridicule." 60 Frederic Cuvier said of his brother Georges that he put ideas of species transformation . . . in the rank of those frivolous games of the imagination with which the truth has nothing in common; with which one may amuse oneself when they are skillfully and gracefully presented, but which lose all their charm when taken seriously.5'

It requires no great feat of the imagination to suppose that Cuvier at times made light of the ideas of Lamarck-one is simply left wondering what specific plaisanteries he conceived. If most of these productions are lost forever to the historian, owing to Cuvier's program of public silence in such matters, a 48. Fragments biographiques, (see fn. 3 above), p. 81. 49. Institut de France (Fonds Cuvier), MS 3065, p. 122. The manuscript, entitled "Sur la variet6 de composition des animaux," had only been just begun when Cuvier died in 1832. The original French of the passage cited is: "en verite ses explications sont quelquefois bien plaisantes malgr6 l'admiration que quelques naturalistes affectent de montrer pour elles." 50. Legons d'anatomie comparFe, 2nd ed. (1835), I, 101. 51. "Observations preliminaires," Recherches sur les Ossemens fossiles, 4th ed., 1 (1834), viii.

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few examples still remain.52 Perhaps the best example comes from the manuscript of the first edition of Cuvier's Recherches sur les Ossemens fossiles, now considered at the Museum national d'Histoire naturelle in Paris. In the introductory discourse to the published version of this work there is a lengthy paragraph presenting ideas which are attributed somewhat vaguely in a footnote to De Maillet, Rodig, and Lamarck.53 An examination of the published passage indicates that the ideas referred to are for the most part Lamarck's. The passage, which follows a brief discussion of the theories of the earth of Leibniz, De Maillet, and Buffon begins: In our times, some freer minds than ever have also wanted to exercise themselves on [the subject of the origin of the earth]. Some writers have reproduced and prodigiously extended the ideas of De Maillet. They say that all was fluid in the origin; that the fluid engendered at first some very simple animals such as the monads or other infusorial and microscopical species, that, through time and in taking up diverse habits, the races of these animals became more complex and diversified themselves to the point where we see them today.54 At this point in the published work Cuvier continues with a reference to ideas which can be found in Lamarck's Hydrogeologie. At this point in the manuscript, however, Cuvier continues with the following caricature of evolutionary thought, which never appeared in print: . . .that the habit of chewing, for example, resulted at the end of a few centuries in giving them teeth; that the 52. See in the published works Cuvier's Histoire des sciences naturelles . complet6e etc. par Magdeleine de Saint-Agy, III (1841), 85-88; Legons d'anatomie compar6e, 2nd ed., I (1835), 99-102 (esp. p. 101); and for general comments upon Lamarck's work, Cuvier, "Ploge de Lamarck." 53. Recherches sur les Ossemens fossiles (Paris, 1812), I: 28. The footnote reads: "Voyez la Physique de Rodig, p. 106. Leipsig, 1801; et la p. 169 du 2e tome de Telliamed. M. de Lamarck est celui qui a developpe dans ces derniers temps ce systeme avec le plus de suite et la sagacite la plus soutenue dans son Hydrog6ologie et dans sa Philosophie Zoologique." In the 1830 edition of the Discours sur les Revolutions . . . du Globe . . . and in the fourth edition of the Ossements fossiles the phrase "et la sagacit6 la plus soutenue" is dropped from the footnote. Cuvier's reference to Telliamed is apparently to the 1749 edition of that work, where beginning on page 169, volume 2, the idea that flying fish may be transformed into birds is presented. The Rodig work referred to is apparently the work entitled Lebende Natur. Page 106 of this work also has a discussion of the transformation of flying fish into birds. 54. Recherches sur les Ossemens fossiles, I, 28.

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Lamarck and the Politics of Science habit of walking gave them legs; ducks by dint of diving became pikes; pikes by dint of happening upon dry land changed into ducks; hens searching for their food at the water's edge, and striving not to get their thighs wet, succeeded so well in elongating their legs that they became herons or storks. Thus took form by degrees those hundred thousand diverse races, the classification of which so cruelly embarrasses the unfortunate race that habit has changed into naturalists.55 The above passage provides an excellent example not only of Cuvier's incisive rhetoric but also of his general inclination to confront Lamarck's theory, when he mentioned it at all, on the level of the examples offered in its support, and not in its general aspects. One should also remark that the discussion of the hen changed by habit into a heron or stork, exaggerated though it may be, does have a counterpart in Lamarck's writings; the example of the fish being changed into a duck and vice versa, however, may be traced perhaps to DeMaillet or Rodig but not to Lamarck. In discussing Lamarck, Cuvier characteristically lumped him together with scientifically disreputable popularizers such as De Maillet, Rodig, and Robinet.56 Lamarck's cause cannot have been helped by the association. Even a sympathetic observer such as ttienne Geoffroy SaintHilaire had to admit that Lamarck's presentation suffered from some "great flaws in execution." These flaws, said Geoffroy Saint-Hilaire, were what Lamarck's adversaries used to Lamarck's disadvantage: In order to arrive at the demonstration of the true principle of the variability of forms in organized beings, Lamarck too often produced profuse, exaggerated, and for the most part 55. Musdum national d'Histoire naturelle, MS 631, pp. 35-36. The original is as follows: "que l'habitude de macher par exemple, finit au bout de quelques si6cles par leur donner des dents; l'habitude de marche, leur donna des jambes; les canards a force de plonger devinrent des brochets; les brochets a force de se trouver a sec se chang6rent en canards; les poules en cherchant leur pature au bord des eaux, et en s'efforqant de ne pas se mouiller les cuisses, r6ussirent si bien a s'alonger les jambes qu'elles devinrent des herons ou des cigognes. Ainsi se formerent par degres ces cent mille races diverses, dont la classification embarrasse si cruellement la race malheureuse que l'habitude a changee en naturalistes." It may be noted, as Coleman, in Georges Cuvier (p. 191), has already done, that the manuscripts of Cuvier's published works almost invariably correspond precisely to the published works themselves. An omission of the sort represented by this passage is quite rare. 56. See the first two items cited in fn. 52 above and Cuvier's article "Nature," Dictionnaire des sciences naturelles, 34 (1825), 261-268.

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erroneous proofs, which his adversaries, adept at seizing the weak side of his talent, hastened to pick up and bring to light.57 It is difficult to estimate just how much the posture of Cuvier toward Lamarck's evolutionary ideas may have influenced contemporaries who might otherwise have been disposed to give Lamarck's ideas some serious attention. Presumably Cuvier's influence in this regard was considerable. The combination of public neglect and private ridicule seems to have been devastating for Lamarck's evolutionary theory. To criticize Cuvier's antievolutionary role in the history of science, however, without at the same time being critical of Lamarck's own responsibility for the fate of his own ideas, is to present a very one-sided analysis. Lamarck was unquestionably well aware that Cuvier claimed never to go any farther than the facts would allow him. Lamarck was similarly well aware that Cuvier's example was a weighty one in the eyes of the vast majority of the naturalists of the day. There is a strong likelihood that one reason Lamarck did not tie at least the early presentations of his evolutionary theory to factual evidence was that his theory did not initially arise in response to specific facts, or at least not to specific facts that directly suggested the process of evolution, so much as it arose as the result of considerations of certain broad problems such as the origin of life and the possible extinction of species. But it seems that after Lamarck conceived of his evolutionary theory, for a number of reasons which have been suggested here, he proceeded to present it in a highly speculative fashion, paying little attention to factual evidence that might have been summoned in its support. Almost flamboyant,-considering the circumstances-in his inattention to the sort of details needed to give his theory some semblance of legitimacy in the eyes of most of his contemporaries, he left his work open to ridicule. As Raspail, the sharp-tongued observer of the French scientific scene, remarked in the year after Lamarck's death: "Among us ridicule is a deadly weapon; all its blows are mortal." 58 In the course of his writings Lamarck made a number of statements of considerable wisdom concerning scientific methodology and the intellectual and psychological problems of the individual scientist. Some of these, it must be admitted, contrast 57. Fragments biographiques, p. 81. 58. Annales des sciences d'observation, 3 (1830), 277. The comment comes from an article on teratological studies entitled "Monstruosites remarquables" in which Raspail defends the researches of ttienne Geoffroy Saint-Hilaire.

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Lamarck and the Politics of Science rather strikingly with certain aspects of his own scientific work. It is especially interesting to note that he once observed: "Men who strive in their works to push back the limits of human knowledge know well that it is not enough to discover and prove a useful truth that was previously unknown, but that it is necessary also to be able to propagate it and get it recognized." 59 Lamarck was capable of prescribing the appropriate course of action but he was incapable of executing it. EPILOGUE Lamarck viewed man as a part of nature. Though he hedged somewhat in his comments about man's animal origins, his thoughts on this subject were clear enough. For him to say that man was a part and a product of nature was not the same, however, as to say that man was an unreservedly admirable product of nature or nature's ultimate product (despite what one might be led to suppose on the basis of some of his comments about the "plan" of nature). Lamarck viewed man as "the most surprising and admirable" being on the earth, but also as combining in himself the worst sorts of qualities as well as the best.60 Self-concern, an excess of which results in egoism, and a desire to dominate were seen by Lamarck as integral parts of human nature.6' The mention of these views is not meant to suggest that the pessimistic side of Lamarck's thoughts on human nature was a derivative of his own experiences within the French scientific community. Conversely, though, it seems that his thoughts on the way individual scientists at times behaved would not have brightened his outlook on human nature. On the broadest scale, Lamarck's view of man could be extremely grim. Man, as Lamarck saw him, was not simply a part of nature, but a disruptive part. It is significant that the only extinctions of species that Lamarck could imagine were extinctions caused by man. While others were writing on the great progress man would experience in the future, Lamarck, though not denying man's potential, expressed serious reservations. The following passage is offered in closing as Lamarck's most disconcerting comment on man and as surely one of the very earliest prophecies of global ecological disaster as the result of human action: By his egoism too short-sighted for his own good, by his 59. Philosophie zoologique, II, 450. 60. "Homme," Nouveau Dictionnaire d'histoire naturelle, 15 (1817), 270. 61. Ibid., p. 273.

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tendency to revel in all that is at his disposal, in short, by his lack of concern for the future and for his fellow man, man seems to work for the annihilation of his means of conservation and for the destruction of his own species. In destroying everywhere the large plants that protect the soil in order to secure things to satisfy his greediness of the moment, man rapidly brings about the sterility of the ground on which he lives, dries up the springs, and chases away the animals that once found their subsistence there. He causes large parts of the globe that were once very fertile and well populated in all respects to become dead, sterile, uninhabitable, and deserted. Neglecting always the words of experience, abandoning himself to his passions, he is perpetuually at war with his own kind, destroying them everywhere and under all pretexts, so that one sees formerly great populations become more and more diminished. One could say that he is destined to exterminate himself, after having rendered the globe uninhabitable.62 Acknowledgments The author gratefully acknowledges the permission of the Museum d'Histoire naturelle and the Institut de France to consult the manuscript sources cited in this paper. The research for this paper was supported in part by a National Science Foundation travel grant. 62. Ibid., pp. 270-271 n.

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The Originsof the SpiralTheory of Phyllotaxis WILLIAM M. MONTGOMERY Department of History University of Texas, Austin

In September 1829, at the Convention of German Scientists and Physicians at Heidelberg, two young botanists, Carl Schimper and Alexander Braun, presented papers outlining a new theory describing the distribution of leaves around an axis, or, to use the botanical term, phyllotaxis.' The theory broke with past writings on the subject in two essential respects: it postulated that all leaf distribution should be understood as a spiral and, more importantly, that all possible spiral variations may be defined by the fractions of several mathematical series well known to students of the theory of numbers. Although their fellow botanists applauded the originality and elegance of the spiral theory, not all of them would accept it in the form that Schimper and Braun proposed. Auguste and Louis Bravais wanted to revise the theory for empirical reasons, suggesting some numerical values slightly different from those of Schimper and Braun.2 Julius Sachs mistrusted the theory for epistomological reasons; to him it seemed to lack a satisfactory causal explanation and was too heavily laden with fanciful numerology.3 Though twentieth-century scientists have paid 1. Anon., "Botanische Verhandlungen bei der achten Versammlung deutscher Naturforscher und Aerzte von 18. bis 24. September 1829 in Heidelberg," Flora, 12 (2) (1829), 591, 602-604. I am indebted to Professor Adolf Meyer-Abich for calling my attention to two recent papers describing the careers of Schimper and Braun: Karl Magdefrau, "Karl Friedrich Schimper. Ein Gedanken zu seinem 100. Todestag," Beitrage zur naturkundlichen Forschung in Siidwest-Deutschland, 27 (1968), 3-20; Brigitte Hoppe, "Deutscher Idealismus und Naturforschung. Werdegang und Werk von Alexander Braun (1805-1877)," Technik Geschichte, 36 (1969), 111-132. Part of the research for this article was completed in Marburg, Germany, with the aid of an exchange scholarship of the Federation of GermanAmerican Clubs. 2. Auguste et Louis Bravais, "Essai sur la disposition des feuilles curvis6rikes," Annales des Sciences Naturelles, 7 (Bot.) (1837), 42-110. 3. Julius Sachs, A History of Botany (1530-1860), trans. Henry E. E. Garnsey, rev. Isaac B. Balfour (Oxford: Clarendon, 1890), pp. 163, 168. Journal of the History of Biology, vol. 3, no. 2 (Fall 1970) pp. 299-323.

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proportionately less attention to the theory than their predecessors, interest has not died out, and developments in it have continued up to the present day.4 The basic epistomological questions raised about Braun's and Schimper's work make it more important to the historian than most scientific ideas of its degree of specialization. Furthermore, the "philosophical" significance of what they wrote is complemented by the charm of its ingenuity, an ingenuity that even their detractors have been pleased to acknowledge. Braun and Schimper naturally had a number of predecessors in the study of leaf arrangement. The earliest of these seems to have been Andrea Caesalpino, who demonstrated an awarness of geometrical regularity in leaf distribution in his De plantis libri (1583).5 Somewhat later Sir Thomas Browne treated the matter in his neo-Pythagorean The Garden of Cyprus (1658). Searching nature for examples of the X-shaped quincunx pattern, he discovered catkins, artichoke leaves, thistle heads, and pine cones. He noticed five-petaled flowers and cycles of five leaves rounding a stalk, and he even perceived the quincunx in decussate leaves.6 His term acquired a more specific meaning when Nehemiah Grew applied it to flowers of five petals. This usage of the word in the Anatomy of Plants (1682) has continued to the present day. Grew also referred to Browne's use of the word with respect to leaf distribution but failed to indicate precisely what it might mean.7 The term's application to petals is of less interest for the story of the spiral theory; but one biologist, the Genevan, Charles Bonnet, finally gave it some precision in his study of leaves. Although Bonnet did not mention Browne in his book, Recherches sur l'usage des feuilles dans les plantes (1754),8 he may well have known where the word quincunx originated. Grew's book had been translated into French,9 and Bonnet probably read it. Never4. R. Snow, "Problems of phyllotaxis and leaf determination," Endeavour, 14 (56) (1955), 190-199. See also E. G. Cutter and B. R. Voeller, "Changes in leaf arrangement in individual fern apices, "Journal of the Linnean Society of London (Bot.), 56 (366) (1959), 225-236. 5. Sachs, History, p. 163. 6. Geoffrey Keynes (ed.), The Works of Sir Thomas Browne, Vol. IV, Hydriotaphia; Brampton Urns; The Garden of Cyrus (London: Faber & Gwyer, 1929), pp. 70-88. 7. Nehemiah Grew, The Anatomy of Plants (London: W. Rawlins, 1682), p. 165. 8. Charles Bonnet, Recherches sur l'usage des feuilles dans les plantes . . .(Gbttingen and Leyden: E. Luzac, fils., 1754). 9. Nehemiah Grew, Anatomie des plantes . . . (Leyden: P. Vander Aa, 1685).

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The Spiral Theory of Phyllotaxis theless, Browne was not alone in inspiring Bonnet's ideas about the arrangement of leaves; there was also his fellow Genevan, the mathematician and philosopher, Louis Calandrini. Unfortunately, the only available evidence for Calandrini's thoughts on the subject seems to be Bonnet's book itself, which makes it necessary to consider Calandrini as a footnote to the better known author. Bonnet believed that the principal function of leaves is the absorption of moisture and that this task can be most effectively performed if the leaves cover one another as little as possible. He recognized five forms of leaf distribution, three of which were already commonly acknowledged by the botanists of his day though not necessarily under the same names. These were alternate, descussate (which Bonnet termed a Paires croisees), and whorled distributions. His fourth order was the quincunx. In describing it he asked his readers to imagine five longitudinal lines equally spaced around a stem. The first leaf appears on the first line, the second leaf above it on the third line, the third leaf on the fifth line, the fourth leaf on the second line, and the fifth leaf on the fourth line. The first leaf of the new series then appears on the first line directly above the first leaf of the series below. Bonnet's quincunx differs from the arrangement described by Browne in that Bonnet's spiral of five leaves circles the stem twice, whereas Browne's circles it only once. Furthermore, Bonnet restricted the term quincunx to this one formation rather than applying it loosely to any and every overlapping leaf arrangement. This stipulation, however, was not entirely without exception, for Bonnet described certain variations on the basic quincunx pattern. First of all, he noted that a few cycles contain more or fewer than five leaves. Equally important was his observation that the first leaf of each new cycle does not really stand directly above the first leaf of the preceding cycle. In all the plants he examined there was a slight twist either to the left or right so that the first leaves of each cycle, and hence the cycles themselves, gradually described a spiral around the stem. This fact he took to be a further example of nature's preventing one leaf from covering another. It was a variation, though, which he found in none of the other orders-only in the quincunx.10 Bonnet called his fifth order the redoubled spiral. This con10. Bonnet, RecheTches, pp. 160-181.

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sisted of several rows of parallel spirals running around the stem. In the pine he found equidistant, parallel spirals of seven leaves each, a total of twenty-one leaves per cycle. In the fir he noted five parallel spirals of eleven leaves each for a total of fifty-five leaves." On an attached table he listed twentyeight herbaceous and thirty-three woody genera whose leaves were distributed in a quincunx formation, but pine and fir were his only examples of redoubled spirals.'2 The latter category is particularly interesting, however, for Bonnet attributed its discovery to Calandrini."3 In the book's acknowledgements Bonnet had also said: The engraving which portrays the five orders of distributions which are observed in the leaves is from the hand of Mr. Calandrini to whom I further owe the observations and views which have served the basis of my work.14 Whether this blanket acknowledgement may also bear on Bonnet's idea of the quincunx is unknown. Calandrini was cited in a number of places in the book, but in the chapter on leaf distribution Bonnet only mentioned him in connection with the redoubled spiral. Quite probably the quincunx idea was developed by Bonnet alone, and his friend's engraving represented essentially Bonnet's ideas. In spite of Bonnet's effective presentation, the idea of spiral leaf formations did not pass into the common literature of botany and, hence, remained more or less unknown. In 1811, when the idea was revived by Palisot de Beauvois in a paper he read before the Institut Imperial de France, his hearers were excited by the novelty of it.'5 Palisot briefly outlined Bonnet's system and sought to relate it to his studies of the pith. He explained that in trees with whorled, spiral, or scattered distribution the medulary sheath is angular in shape; but in trees with opposite leaf distribution the medulary sheath is round or oval. Further, in a case of three-leaf whorls, the medulary sheath forms a triangle; and in the cases of four- and five-leaf spirals the medulary sheaths are tetragons and pentagons respectively. According to Palisot, the five-leaf spiral is the most common, 11. Ibid., pp. 165-166. 12. Ibid., pp. 167-168. Bonnet used the word espAces rather than genres, but his examples were of the latter. 13. Ibid., p. 166. 14. Ibid., p. v. 15. Aubert de Petit-Thouars, Histoire d'un morceau de bois (Paris: the author, 1815), pp. 111-113.

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The Spiral Theory of Phyllotaxis but exceptions do occur; in the illustration which accompanied the article he included examples of thirteen-, eight-, five-, and four-leaf spirals. Palisot did not notice that his thirteen-leaf spiral took five revolutions and his eight-leaf spiral three to complete their cycles, whereas the five-leaf spiral took only two-a matter which Carl Schimper would later consider of some importance. Palisot also suggested that alternate leaves might be considered as a spiral of two,'6 but when he set up his own categories of leaf distribution in a second article, he separated them into whorled, opposite, alternate, and spiral. He apparently wanted to include all spirals in the last category but unfortunately added the misleading remark that Bonnet referred to this category as the quincunx. Most of this article was devoted to whorls, but, in closing, Palisot observed that not only are most spirals distributed by fives, but also most sepals, petals, and stamens. He thought this worthy of further consideration.17 Palisot's remarks on leaf distribution, unlike Bonnet's, suffered no neglect. Aubert du Petit-Thouars devoted a chapter of his book, Histoire d'un morceau de bois (1815), to a polemical critique of Palisot's work in which he sought to undermine any of Palisot's possible claims to originality by tracing the origin of the quincunx idea back to Thomas Browne's "ouvrage trescurieux," The Garden of Cyrus, and citing brief comments on the subject made by Grew and Malpighi.18 Aside from these essentially historical remarks, however, he added nothing to the theory itself. The next new ideas on leaf distribution were offered by Augustin P. de Candolle. His Organographie ve'getale (1827) reduced leaf distribution to two great classes: one in which several leaves appear on the same horizontal level, a whorl, and one in which the leaves appear singly. Opposite leaves he 16. Palisot Baron de Beauvois, "Premier memoire et observations sur I'arrangement et la disposition des feuilles; sur la moelle des vegetaux; et sur la conversion des couches corticles en bois," Memoires de la classe des sciences mathematiques et physiques de l'Institute de France, 1811 (pt. 2), 130-132 and plate II. 17. Palisot, "Second m6moire sur l'arrangement et la disposition des feuilles," Memoires de la classe des sciences mathematiques et physiques de l'Institute de France, 1811 (pt. 2), 155-162. 18. Petit-Thouars, Histoire, pp. 111-113. The observations he ascribed to Malpighi I have not been able to locate. Petit-Thouars was cryptic, referring only to the chapter de Foliis on page 48 of the quarto edition. There is such a chapter beginning on that page in Marcelli Malpighi, "Anatomes Plantarum," Opera Omnia (unknown: Vander Aa, 1687), but neither Browne nor the quincunx is mentioned there.

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classes simply as whorls of two leaves. He followed Bonnet's terminology, indicating that opposite leaves may be arranged in paires croisees, but noted also that the pairs may be arranged spirally, that is, displaced at acute angles with several pairs elapsing before one pair falls directly above another again. Likewise, the leaves of a whorl may fall in the intervals between those of the whorls above and below. De Candolle objected to the use of the terms alternate and scattered, as they had often been applied to all leaves placed singly, on the grounds that all distribution shows order of one kind or another. Among leaves placed singly he recognized Bonnet's three categories: alternate, in the strict sense; quincunx; and spiral-reserving the term quincunx for formations of five leaves only and spiral for formations of more than five leaves. In the latter category he mentioned the possibility of triple, five-fold, six-fold or even eight-fold parallel spirals. Thus, he concluded, basically there are only two types of distribution, whorls and spirals, since, in principle, alternate leaves can be regarded as spirals. Moreover, even these two types cannot be completely separated, for many young dicotyledons whose leaves are whorled or opposite gradually acquire spiral or alternate distribution by the elongation of the stem. The opposite process also occurs in monocotyledons, though not as often. De Candolle further commented on spirals that come to resemble whorls by the bunching together of leaves at intervals along the stem. Like Bonnet, he wanted to suggest a physiological reason for leaf distribution. The function of leaves is to decompose carbonic gas and evaporate excess water, which requires exposure to sunlight. Therefore, unless the leaves are placed fairly far apart, they must be arranged so as not to cover one another.'9 The year 1827 was also marked by a German discussion of leaf placement. Carl Friedrich Philipp von Martius of Munich alluded to the matter briefly in a paper he delivered before the Convention of Scientists and Physicians that September in Munich.20 He presented the concluding portion of the paper at the next convention in Berlin in September 1828.21 The author's principal interest was not the distribution of leaves but the structure of flowers; however, he found it necessary 19. Auguste P. de Candolle, Organographzie Veg&tale (Paris: Deterville, 1827), I, 325-331. 20. Carl Friedrich Philipp von Martius, "fiber die Architectonik der Bluthen," Isis, 21 (1828), 522-529. 21. Martius, "uber die Architectonik der Bliithen," Isis, 22 (1829), 333341.

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The Spiral Theory of PhyllotaNis to discuss the former because of the prevailing theory of metamorphosis elaborated in Goethe's The Metamorphosis of Plants (1790).22 According to this idea, the structures of the flower were taken to be "metamorphosised" leaves-a notion not tied to any assumed historical process but rather to an ideal type leaf. Goethe's main concern was establishing a single basic plan for all the appendages of the plant stem.23 His own writings had treated the anatomical form of the various appendages, but now Martius implicitly extended the idea to include the manner of their distribution. Martius dissented from what he described as the common view that the flower develops from whorls of metamorphosised leaves; he saw flowers as developing in spirals.24 He emphasized this more strongly in the second part of the paper, declaring that leaves and flowers form a "unity." Everything in the flower is a "leaf," and these leaves are distributed spirally. He mentioned the familiar five-leaf spiral in connection with flower structures; though instead of citing de Candolle or Bonnet, he commented on the common awareness of this formation among gardeners.25 Martius, in claiming that all leaf distribution is in principle spiral, thus took a step further than de Candolle's suggestion that spirals and whorls might merely be equivalent. He also made a contribution to the metamorphosis theory that broadened its scope and suggested further investigation. In addition to his preoccupation with spirals, Martius exhibited a second concern which bears on the Schimper-Braun theory. Martius was impressed by the common appearance of the numbers three and five in flower formations, associating the former with monocotyledons and the latter with dicotyledons.26 Other authors familiar with the phenomenon included Lorenz Oken, who also ascribed the numbers two and four to the lower acotyledons.27 Schimper himself commented on the popular speculation about these observations.28 Spirals and 22. Bertha Mueller (ed.), Goethe's Botanical Writings (Honolulu: University of Hawaii Press, 1952), pp. 30-78. 23. For a discussion, see Agnes Arber, The Natural Philosophy of Plant Form (Cambridge: Cambridge University Press, 1950), pp. 59-61. 24. Martius, Isis, 22 (1828), 523. 25. Ibid., 21 (1829), 334-336. 26. Ibid., 22 (1828), 524-525. 27. Lorenz Oken, "Rede fiber das Zahlengesetz in den Wirbeln des Menschen," Festreden der Koniglichen Akademie der Wissenschaften zu Miinchen, 2 (1826-1835), 13. 28. Carl Schimper, "Beschreibung des Symphytum Zeyheri und seiner zwei deutschen Verwandten der S. bulbosum Schimp. und S. tuberosum

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numerical formations, then, were current interests of botanists, and it did not take long for Schimper and Braun to respond to them. The young scientists seized on the topic almost immediately. According to a footnote in the published version of the Heidelberg paper, Schimper claimed he had been working on the paper for "a couple of years." 29 If we take that assertion literally, it would date the beginning of his investigation to some time in 1827. Braun was evidently not behind him. In a letter dated August 1831, Braun ascribed his first serious interest in leaf formation to a discussion with Johannes Rbper, whom he visited in Basel during the spring of 1827, and to R6per's article on inflorescence of the same period.30 At that time Braun and Schimper had ample opportunity to discuss phyllotaxis. Their friendship first developed when they were students together in Heidelberg. Braun's last semester there was the summer of 1827. Attracted by the reputations of the Naturphilosophen, Friedrich Schelling and Lorenz Oken, he enrolled in the newly established University of Munich for the winter semester of 1827-28; but Schimper remained in Heidelberg until the following year, when Braun's glowing reports induced him to follow.31 The achievement of those two years was described at Heidelberg and published by the Magazin fur Pharmacie in January 1830. Schimper began his explanation of the spiral theory by saying that the length of the stem between each leaf is not important. The key relationship is the angle by which each leaf is displaced from the next as measured to the left or right around the axis. The leaves ascend spirally around the axis until one of them occupies a spot directly above the first leaf. To make the idea clearer, he suggested the image of a pocket watch to represent the cross section through the stem as seen from above. If the first leaf sprouts from the twelve and the next highest from the four, the spiral is to the right -i.e., the privileged point of view is above and within the Jacq. nebst Erlauterungen uber die Asperifolien iiberhaupt, namentlich iuber deren Blattstellung und Inflorescenz und Pflanzen-Ei," Magazin fur Pharmacie, 29 (1830), 16. 29. Ibid., p. 70. 30. Alexander Braun to Johannes Roper, August 31, 1831, Cecilie Mettenius, Alexander Braun's Leben (Berlin: G. Reimer, 1882), p. 197. The article referred to was probably Roper's "Observationes aliquoit in florum inflorescentiarumque naturam," Linnaea, 1 (1826), 433-466. I wish to thank Mr. Jack Vaughn for translating portions of it. 31. (Cecilie Mettenius), "Alexander Braun," Leopoldina, 13 (1887), 53.

306

The Spiral Theory of Phyllotaxis spiral. Since the second leaf falls at four, a divergence of onethird of the circumference from the first, the third must faUl at eight. The fourth falls directly above the first, the fifth above the second, and so forth. Unlike Bonnet, Schimper regarded the cycle as an exact one. For him there was no twist displacing leaf number one of each cycle. Expressing the divergence between leaves as a fraction of the circumference allowed the numerator of such a fraction to indicate the number of revolutions required to complete one period, or cycle, and the denominator to indicate the number of leaves in the cycle-leaf number four of the previously mentioned example being the first leaf of the new cycle and hence not included in the old one. Furthermore, Schimper pointed out that since all the leaves have the same divergence, it does not ordinarily matter which leaf is picked as the first; the counting can begin anywhere. He emphasized that it is not enough to know the number of leaves in a period to know their divergence; one must also know the number of revolutions-that is, the denominator and the numerator of the fraction are required to give the complete information.32 Schimper then directed his attention to the question of which divergences actually occur in nature. Of the natural examples he had discovered, the two "simplest" periods, one-half and onethird, are very common in nature. Furthermore, divergences whose magnitudes lie between these two values are more common than those whose magnitudes lie between one-third and one-fourth. Schimper had not found living examples smaller than one-fourth. Divergences greater than one-half are unnecessary since they can be expressed more easily by their complements; two-thirds, for example, amounts to the same thing as one-third. It all depends on the direction in which one starts around the axis to get to the next highest leaf, and one might as well go the shortest way. More importantly, only a few of the many possible fractions between one-half and one-fourth actually occur in nature33 -a fact which Schimper ascribed to a strict law. "For," he said, "I need hardly remark that everything accidental is completely banned, and that the necessity of the numbers which we have obtained is already proved by the manner in which we have obtained them."34 The determinism is significant. Schimper's world was ruled by logical 32. Schimper, "Beschreibung," pp. 4-13. 33. Ibid., pp. 16-24. 34. Ibid., p. 24.

307

WILLIAM M. MONTGOMERY

necessity; chance and probability were excluded from serious scientific consideration. In character with this outlook, Schimper introduced his law not by citing observations but rather by deducing it from certain ideally postulated conditions. He began by noting that nature prefers the shorter periods, those with fewer leaves and thus divergence fractions of smaller digits. One-half and onethird have the shortest cycles and also the largest divergences. All those fractions lying between them have progressively longer cycles. However, in selecting those divergences between one-half and one-third which should actually appear, nature follows two conflicting laws: one which dictates that leaves should be as widely separated as possible and one which dictates that they approach one another. The divergence one-half represents the first of these laws in its purest form; the divergence one-third represents the second.35 Divergences lying between these two represent a compromise derived by adding the numerators and denominators of the two fractions together: "Not 1 period with 1 revolution and 2 members, not 1 period with 1 revolution and 3 members, but 1 period with 1 + 1 revolutions and 2 + 3 members is formed = 2/5." 36 Further examples are produced simply by adding numerators and denominators of the two previous ones: 1/3 + 2/5 = 3/8.37 Now neither of these new values lies exactly between one half and one-third. Both of these values are in fact part of a series: 1/2, 1/3, 2/5, 3/8, 5/13, 8/21, 13/34 . . . Although Schimper did not say so, this series is generally called the Fibonacci series after its medieval inventor, Leonardo Fibonacci of Pisa. Schimper perceived in the series a very general significance, for it progressed "as the path of nature requires everywhere, which (process) never increases endlessly, but according to a law of restraint, the great and general law of discontinuity, (natura non facit saltus is the greatest untruth) insists on limitation and simplicity." 38 It is important to note that Schimper did not regard the Fibonacci series simply as a basic, unexplained given with a purely empirical significance. Nor was he proposing a mystical numerology-a neo-Pythagorean conception of nature in which Number determines all. The mathematical series was the product of still more basic causes, which Schimper could describe only 35. 36. 37. 38.

Ibid., p. 25. Ibid., p. 26. Ibid. Ibid., p. 27.

308

The Spiral Theory of Phyllotaxis vaguely. At this point he tried to explain them in a manner typical of Naturphilosophen, as the resolution of two dialectically conflicting forces. Yet the explanation did not completely satisfy him, and he was to return to the problem again. For the moment, though, all he could do was declare "that the number itself is only a product and is derived from the living relationships in which the leaf organs appear through their production."39 Schimper's next difficulty was to explain the existence of some anomalies, for there are divergences between one-half and one-third that do not correspond to the Fibonacci series, although they are presumably still related to it. The divergence 18/47, which Schimper found in cedar cones, is made up of a numerator, 2+ 3 +5 + 8 = 18, and a denominator, 5 + 8 +13 + 21 = 47. There are also thistle varieties with an involucral divergence determined by adding the numerators and denominators of 1/2, 1/3, 2/5, 3/8, 5/13, 8/21, and again 5/13. This produces 25/65.40 "Thus," concluded the triumphant author, "every appearance of accident vanishes."4' Later he added the somewhat inconsistent remark that fractions between one-half and one-third not belonging to the series either do not occur or occur "only very accidentally."42 However, this fact did not alter, in his own mind, the "necessity" of the "number relationships." The stumbling block of the anomalous divergences was to lead the consistent Braun into even more number-juggling than it had Schimper, for neither could allow "accident" very much interference with the consistency of nature's laws. After all, if one is attempting to demonstrate a common plan for all stem appendages, exceptions must be fitted in. Another theme to be treated was alternating periods. Schimper pointed out that each cycle is a unity in itself, which on a given plant may alternate with others of differing divergence. Such alteration is particularly common in flower parts, whose calyx, corolla, stamens, and carpels often reveal differing divergences-though Schimper denied that the absence of these differences should be ascribed to an abortion. He explained the spiral of flower parts using the example of a rose calyx. It is a five-membered spiral; and, counting from the outside of the bud that produced it, one requires two circuits to include all its members in the order of their appearance.43 The matter 39. 40. 41. 42. 43.

Ibid., Ibid., Ibid., Ibid., Ibid.,

p. 33. pp. 28-33. p. 31. pp. 32-33. pp. 35-42.

309

WILLIAM M. MONTGOMERY

of flower parts naturally led to the question of whorls. Following the line of argument initiated by Martius, Schimper declared, "Whorled leaves in the sense in which they are usually defined, that they originate around one and the same point or node, i.e., in the same level of the stem, do not exist."44 He perceived a "definite succession" in them that was noticeable even in the case of decussate and opposite leaves. This exclusiveness of spiral forms throughout the plant inspired an italicized exclamation centered in the middle of the page: Thus nowhere an accidentl" 45 Following this pronouncement Schimper placed a catalogue of the species and genera which exemplify the various divergences appearing in nature. For the divergence 1/2 he enumerated a large number of cases, but anomalies continued to plague him. He cited the example 7/15, which is very close to 1/2, and the example 3/7, which is similarly close to 2/5. For 2/5 itself there are many cases, and the number of examples for 3/8 is likewise large. Five-thirteenths is well represented, but 8/21, 13/34, and 18/47 are not as common. Seven-twentieths, almost 1/3, appears in one case; 1/3 itself is uncommon. Among the divergences between 1/3 and 1/4 he found examples of 2/7 and 5/18. One-fifth and 1/8 occur in whorls. He also cited many whorls of two and three leaves but fewer of four or more. To assist his readers with some of the more complicated formations, he listed the divergence of a large number of involucres.46 As indicated earlier, Schimper's practice of assigning all divergences values less than one-half was purely a matter of convenience. Five-thirteenths, for example, has a complement, eight-thirteenths, which may be obtained by measuring the long way around the stem. However, Schimper thought that the choice between the two modes of measurement is not entirely arbitrary; for the overlapping sheaths of Umbelliferae and Junci convinced him that leaves have a younger and an older edge. At the node, the older portion of the leaf appears lower on the stem, that is, on the outer circumference. The edge of the sheath which is overlapped he considered younger; the sheath is thus rolled in itself, not on itself. Since the older edge of the leaf is easily distinguished from the younger, one can determine the true direction of the spiral. Sheaths which succeed one another in the same direction he termed syn44. Ibid., p. 37. 45. Ibid., p. 44. 46. Ibid., pp. 46, 53-63.

310

The Spiral Theory of Phyllotaxis tropic; and the natural spiral of many of them did, he thought, proceed the long way around the axis. Strictly speaking, then, the larger of the two possible divergence fractions is the true description. Moreover, Schimper found that the direction of most sheaths alternates with each leaf, placing all the older leaf edges on one side of the stem and all the younger edges opposite them in an antitropic formation.47 That such an organization in no way resembles a spiral did not seem to occur to Schimper. The ambiguous outcome of this investigation aside, it was, nevertheless, an interesting effort on Schimper's part to look beyond the numerical series for a more basic insight into the origin of leaf formations. At the conclusion of his paper, the author commented on the tentative state of his theory and promised a more thorough publication on the subject in the near future.48 However, before considering Schimper's proposed work, I would like to describe the paper on evergreen cones that Braun brought out in 1831. Unlike Schimper's article, Braun's is not the text he delivered in Heidelberg in September 1829. The paper is much too long, about 200 pages, to have been presented orally; and it contains no remarks to an obviously present audience such as appear in Schimper's paper. However, it is probably safe to assume that the paper grew out of the lecture Braun presented at Heidelberg, and it contains no indication that the author had changed his mind about any important point since that time. In substance the paper agreed with Schimper's presentation, and Braun acknowledged his friend's priority.49 Nevertheless, Braun's emphasis was slightly different. He devoted a great deal of space to the practical matter of determining the divergence angle of actual specimens and took pains to work out elaborate arithmetical consequences of Schimper's basic insight. In treating the matter of exceptional divergences, Braun also launched out in a new direction. He proposed the existence of a second mathematical series of divergences lying between one-third and one-fourth. Then, with more inventiveness than plausibility, he developed an elaborate scheme for explaining cases that were covered by neither series. If, in the latter effort, Braun laid himself open to the charge of having 47. Ibid., pp. 47-52. 48. Ibid., pp. 70-71. 49. Alexander Braun, "Vergleichende Untersuchung iiber die Ordnung der Schuppen an den Tannenzapfen als Einleitung zur Untersuchung der Blattstellung uberhaupt," Verhandlungen der Kaiserlichen LeopoldinischCarolinischen Akademie der Naturforscher, 15 [1] (1831), 197.

311

WILLIAM M. MONTGOMERY

dabbled in numerology, it certainly did no harm to his reputation for industry and resourcefulness. Braun agreed with Schimper's contention that whorls are arranged spirally, thus granting the spiral law a universal application. Turning to evergreen cones, he pointed out that each cone exhibits a number of more or less obvious sets of parallel spiral lines. The steeper these lines, the more numerous they are. In the example considered, Braun found the sets of five and eight the most obvious; but there is also a less obvious set of thirteen steeper lines and a vertical set of twenty-one lines. Obviously, these are not the basic spiral, for each of the five parallel lines can contain only one-fifth of all the scales on the cone, and each line from the set of eight parallel lines can contain only one-eighth of them. However, if one observes the less steep sets of lines, one finds a set of three, a set of two, and finally a single spiral which contains every scale on the cone. Since there are on this cone twenty-one possible horizontal displacements, each period of the spiral contains twenty-one scales; and the twenty-second scale falls directly above the first. Now the twenty-second scale does not fall above the first in a single revolution of the cone. In fact, it takes eight revolutions because each scale is separated from the next highest by a fraction of 8/21 of the circumference of the cone. From this point Braun launched a rather clever explication of the arithmetical relations among the secondary spirals and between them and the basic spiral.50 These considerations were entirely his own, for there is nothing comparable to them in the Schimper article. They are, however, of more mathematical than botanical interest, adding nothing basically new to the theory. Getting back to more fundamental matters, Braun warned that the divergence of a particular leaf formation can hardly be determined by direct measurements since, for example, the difference between the divergences 13/34 and 55/144 is less than 81/2 minutes of arc. The only way to determine the divergences is to count the number of members and revolutions in the basic spiral. In cases where the basic spiral is difficult to find, one must deduce it by observing the composition of the secondary spirals. To give the reader a notion of what actually appears in nature, he cited examples of cones which have divergences all the way from 2/5 to 21/55. In this it 50. Ibid., pp. 204-237.

312

The Spiral Theory of Phyllotaxis appears that the divergences might sometimes vary not only within the same species, but even on the same cone. It was only at this point that Braun explained the system of adding numerators and denominators by which the series of divergences is built up. This generally followed Schimper's explanation; however, in Braun's account the two conflicting principles according to which leaves diverge from and approach one another do not appear. Braun also added a number of features of his own. Among these was his expression of the series in a much more general fashion: 1+

I

+ 1

+ 1 +...

He indicated further that if one alters the first fraction in the series to 1/2, 1/3, or 1/4, one produces similar series of fractions lying between 1/3 and 1/4, 1/4 and 1/5, and 1/5 and 1/6.51 Braun, too, included a catalogue of the examples of all the divergences he had discovered, listing not only higher plants but also leaf mosses. In one family, the Compositae, he found so many examples that he included a separate list of them. While examining whorls, especially Compositae periclinia, he noted that some larger, greener leaves of the whorl tend to cover the edges of the smaller, paler ones-a fact he took to mean that they do not appear simultaneously but according to the same ordering that the more obvious spiral forms exhibit.52 Like Schimper, Braun was concerned by the many leaf formations that were not included in the basic series. However, Braun's effort to work them into the system was much more elaborate than that of his friend, and it led down a rather dubious path. Braun began with an example Schimper had cited, the divergence 18/47. This is produced not by the combination which would normally appear in the series, 8 + 13 - 21, 21 + 34 = 55 but rather by a combination in which 5/13 is substituted for 51. Ibid., pp. 238-260. 52. Ibid., pp. 262-289.

313

WILLIAM

M. MONTGOMERY

8/21. This procedure of skipping a member in the normal succession of the series can produce a variety of anomalies: 3 + 8 = 11 or 2 + 5 = 7. 5 + 13 = 18 8 + 21 = 29 The anomalies seemed important, for Braun found species in which some of them were the standard cases.53 Inconveniently, not all of them could be covered by the above method, and Braun was obliged to invent new ways to generate the necessary fractions. He did this by deriving secondary series from each member of the basic series. TABLE 1. Secondary Series

0+n.1 1) 1+ n.2 2) 1+n.1 2+n.3 3)

+n*2-

3+n.5

8

9

3

4

5

113

215

517

419

5f11

6113 7115

8117

9119

= 215

318

4111

5114

6117

7120 8123

9f26

5113

7118

9J23 11128 13133 15138 17143

-=

318

6

7

2

n

10

...

1021

. ..

12

10129

11132

...

113

19148

21f53

...

215

..

318

...

5113

26169 29177 32185 5113 8121 ll129 14137171452015323161 4) 2+n3= 5 ? n.8 5n = 8121 13134 18147 23160 28173 33186 58199 431 112 481125 531138 5) 8+n.13

In Table 1, as n increases, the successive derivative fractions approach the basic fraction as a limit. Natural examples do not exist for all the fractions indicated in the table. From the series approaching 1/2, Braun found them up to n = 7, for 1/3 up to n = 14, for 2/5 up to n = 10, and for 3/8 up to n = 4.54 The secondary series were an important phenomenon for Braun. "It will show us," he said, "that the examination of the relationships which diverge from the basic series leads not at all into an unlimited field of blind deviation from the rule but rather directly again back to the law itself.55 In other words, he was quite as insistent as Schimper upon eliminating the appearance of deviation. Moreover, Braun was not finished. It was, after all, possible to derive a further series from each of the secondary series. For 53. Ibid., pp. 291-302. 54. Ibid., pp. 306-309. 55. Ibid., pp. 309-310.

314

0o

The Spiral Theory of Phyllotaxis example, one could use the series approaching 1/2, (O + n.l)/ 1 + n.2. The last member of this series which also corresponds to the basic series occurs when n 2 for (O + 2.1)/ (1 + 2.2) = 2/5. If one adds to its numerator and denominator the numerator and denominator of the first deviant member, 3/7 (when n = 3), one has the beginnings of a whole new series, which can be extended in the same fashion as the basic one: 2/5, 3/7, 5/12, 8/19, 13/31, 21/50.. ..56 One need not stop with 3/7 because this procedure may be repeated for every other member of the secondary series. Braun's table shows what happens. TABLE 2. Tertiary Series I.

Of1,

113,

2f5, 318, 5f 13, 8121,

317, 5112, 81 19, 13131,

II.

419, 7f 16, 11125, 18141,

III.

5111, 9120, 14131, 23151,

IV.

...

6113, 11f24, 17157, 28161,

...

112

From series I he found natural examples up to 8/21, from series II up to 11/25, and from series III up to 14/31. However, from a further table constructed to approach 1/3 and 2/5, he discovered only three natural examples.57 Braun now turned to the more constructive activity of describing the basic series whose values lie between 1/3 and 1/4. It appears as follows: 1/3, 1/4, 2/7, 3/11, 5/18, 8/29, 13/47. . . . He also noted the possibility of similar series between 1/4 and 1/5, 1/5 and 1/6, and so forth. He included a catalogue of the natural examples he had discovered from the smaller divergence series. Naturally, too, there are exceptions to these, formations which Braun included by erecting more series up series, though in a slightly different way from what he had done with the group 1/2, 1/3, 2/5, 3/8.. . B8 Braun concluded his article by repeating Schimper's argument that leaves have an older and a younger half. Rolled sheaths, he agreed, do show the true succession of the spiral to be the long way around the stem; but he thought the simple manner of expressing divergences ought to be maintained for 56. Ibid., p. 313. 57. Ibid., pp. 314-315. 58. Ibid., pp. 318-333.

315

WILLIAM M. MONTGOMERY

the sake of convenience.69 Furthermore, he valued such considerations highly as a means of penetrating beyond mathematical rules to basic causes. I only want to indicate in the last observations that the true nature of leaf placement is not yet comprehended through its purely mechanical determination, with which we have almost completely occupied ourselves; to the circle of scientific research in which we have been active up to this point, another is attached, which has for a goal discovering the true and not merely the apparent progression and origin of leaf placement. It is chiefly the observation of the rolling of sheaths that draws up the curtain, which up to this point has veiled the higher goal.60 Braun was now able to announce that the goal was in sight. He promised his readers a forthcoming book by Carl Schimper to be published in Cotta in 1831 under the title Die Blatterzeugung im Gewichsreich.61 Braun's mentioning a new book by Schimper was more specific than what Schimper himself had said in his own article. Evidently, in the time lapse between the two papers, Schimper had developed his plans to the point of agreeing on a deadline with his prospective publisher. However, there were suggestions about the book's contents even in his own paper. He intended to devote space to the natural direction of spirals, as Braun indicated; but he further wanted to talk about changes in divergence between cycles, particularly in relation to bracts and flowers.62 Already, in early 1830, Schimper had firm ideas about new developments in the spiral theory and plans to bring these views before the public. But at this point one encounters a mystery, for his book did not appear in 1831. In fact, it did not appear at all, though a few plates were printed. However, in the aftermath of the July revolution the business outlook was so unfavorable that Cotta, the publisher, abandoned the project. It is unclear why he failed to revive it with the return of normal conditions. It has been suggested that Schimper simply failed to complete the project; such failures were not uncommon with him.03 On the other hand, in January 1834 Braun wrote his old friend George Engelmann that the pub59. Ibid., pp. 383-386. 60. Ibid., p. 386. 61. Ibid., p. 387. 62. Schimper, "Beschreibung," pp. 69-71. 63. L. Jost, "Eine unbekannte Schrift Karl Schimpers," deutschen botanischen Gesellschaft, 58 (1940), 307-308.

316

Berichte der

The Spiral Theory of Phyllotaxis lisher's son had decided to revive the book,f64 which suggests that a manuscript may have been available after all. In any case the decision was not carried out. Meanwhile, Schimper delivered a lecture on phyllotaxis to the botanical section of the Convention of Scientists and Physicians meeting at Stuttgart in September 1834. At its conclusion, the presiding officer, Christian Nees von Esenbeck, announced that it would be printed by the Leopoldinische Akademie.165This did not happen either. Nevertheless, we know Schimper was still seeking a publisher, for in October he approached the editor of Flora with a proposal. It was later publicly explained that the editor lacked the space for what Schimper had in mind; the necessary plates were evidently a particular obstacle.66 The public explanation does not tell the whole story, however, for only five months later Flora printed a reconstruction of the Stuttgart lecture, authored not by Schimper but by Alexander Braun 187 The appearance of this paper angered Schimper, and in spite of Braun's generous apology in a later issue, their friendship was permanently affected. According to Braun, the secretary of the botanical section was absent at the time of Schimper's address and thus failed to obtain an abstract. Shortly after the meeting the secretary wrote to Braun in Carlsruhe, asking if Braun could write the necessary summary. As chance would have it, Schimper was also visiting Braun in Carlsruhe; before his departure, Braun was able to present him with a provisional copy of the abstract for correction. Afterward, however, Braun became dissatisfied with the idea of publishing a simple abstract and chose to develop an elaborate reconstruction of the lecture. Because of the Flora publishing deadline, he lacked the time to send this to Schimper for approval.638 In spite of the public explanations of the participants, the entire affair remains mysterious. One has the impression that, however eager Schimper may have been to put his ideas into print, his efforts to do so were in some way unsatisfactory. 64. Alexander Braun to George Englemann, January 2, 1834, Mettenius, Braun's Leben, p. 279. 65. Anon., "Versammlung der Naturforscher zu Stuttgart am 18ten September 1834," Isis, 1836, p. 233. 66. Carl Schimper, "Letter," Flora, 18 [2] (1835), 749-750, 754-755. 67. Alexander Braun, "Dr. Carl Schimper's Vortrage uber die Moglichkeit eines wissenschaftlichen Verstandnisses der Blattstellung, u.s.w.," Flora, 18 [1] (1835), 145-160, 161-176, 177-191. 68. Alexander Braun, "Nachtragliche Erlauterung zu meinem Aufsatz in Nr. 10, 11 und 12 der 'Flora' laufendes Jahres uber Dr. Schimper's Vortrage," Flora, 18 [21 (1835), 738-740, See also W. Hofmeister, "Karl Friedrich Schimper," Botanische Zeitung, 26 (1868), 35.

317

WILLIAM

M. MONTGOMERY

There was talk at the Stuttgart meeting that "Dr. Schimper was not capable of communicating his views understandably." 69 The secretary, in his note to Braun requesting an abstract, remarked, "I consider you-Mr. Schimper not excepted-to be the only one capable of giving a clear, direct overview on two pages of the natural laws in question." 70 Moreover, it was even suggested that Schimper had merely formulated an abstract system from facts originally discovered by Braun. To this Braun's reply was emphatic. He published an apology affirming Schimper's claim to full authorship of the spiral theory and describing himself as a "pupil" of Schimper. Braun defended his friend's hesitancy to publish, noting that the task Schimper had assumed, that of producing an entire system, was much more formidable than his own piecemeal discussion of its details.7' This was probably the nub of the matter. One suspects that Schimper's urgent striving for a complete, all-encompassing system condemned him to perpetual failure. His results pleased neither him nor his audience; and to mask their mutual dissatisfaction, Schimper and his potential publishers played out an elaborate scenario, which always ended in frustration. Returning to the Stuttgart lecture itself, one notes that its unorthodox form of publication was matched by the unorthodoxy of some of its contents. It began ordinarily enough with a summary of matters that Schimper and Braun had already discussed. But on the subject of whorls Schimper introduced the explanation of divergence changes that he had promised in his 1830 paper. He wanted to treat the divergence between two sparate whorls by adding a particular fraction or "prosenthesis" to the numerator of the divergence of the whorls in question. For example, the divergence between paired leaves (a whorl of two) is one-half. The various possible divergences between pairs Schimper expressed as follows:

1 + 1/2, 2

1 + 2/3, 2

1 + 3/5, 2

1 + 5/8, 2

1 + 8/13, 2

.

(In this case the divergences of the prosentheses are being calculated the long way around the axis.) Divergences other than one-half were handled in the same way: 3+ 1/2, 5

3+2/3, 5

3+3/5, 5

3+5/8, 5

69. Braun, "Nachtragliche Erlauterung," p. 741. 70. Mettenius, Braun's Leben, p. 301. 71. Braun, "Nachtriigliche Erl&uterung," pp. 742-746.

318

. .

The Spiral Theory of Phyllotaxis Moreover, the prosentheses themselves form a series, which in turn may appear in whorls with intervals between them. A sample divergence is: 1 + 1/2 !72 1

+2 2

Schimper maintained that these prosentheses affect not only the divergence between whorls of the same stem, but also between leaves on a stem and those on a branch leading from it. The prosentheses had another application, which, according to Braun, filled the last possible gap in the theory of phyllotaxis, thus bringing the entire geometric system to its completion. In most plants, the article observed, the divergences between leaves, bracts, petals, stamens, and carpels usually varies; and in the lower orders, this variation is indeed the rule. As in the transition from one whorl to the next, Schimper found in the transition from one divergence to the next a prosenthesis. There are two forms: a "sharpened transition" and a "mitigated transition." As an example of the former, Schimper cited a transition from 3/5 to 5/8. He arbitrarily selected a small fraction whose denominator somehow seemed related to that of the preceding divergence: (1 + 2)/(5 ? 5) = 3/10. Or another possibility: (0 + 1)/ (5 + 5) = 1/10. This prosenthesis is to be added to the numerator of the following divergence, in this case 5/8, just as in the cases of whorl transitions. For the mitigated transition the situation is reversed; some small fraction with a denominator related to the following divergence is added to the numerator of the preceding divergence. In a case of a 1/2 divergence changing to 8/13, the transition between them is (1 + 1/13)/2 14/26 = 7/13.73 According to the article, " the different possible sizes of these transitions together form a little system, which can be derived from a general law."74 Fortunately, this general law remained unexplained! Yet, however unsatisfactory the prosentheses appear to the modern reader, to Braun and Schimper they seemed most important. Without the idea of a prosenthesis, the spiral theory did not cover the many cycles of differing divergences, which appear especially in flowers-thus leaving the way open to an "arbitrarily handled theory of abortion." 75 72. 73. 74. 75.

Braun, "Dr. Carl Schimper's Vortrage," pp. 165-169, 192. Ibid., pp. 170-176. Ibid., p. 173. Ibid., p. 178.

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With the prosentheses Schimper was attempting to complete a system that included all the phenomena of phyilotaxis. Yet the Stuttgart lecture left one vital topic quite untouched. What did Schimper think about the natural cause of leaf placement? What was the ground that lay beneath the abstract numerical series? Upon approaching the Absolute we are disappointed, for Schimper could never explain it. Some fragmentary suggestions have been discovered, though, in an unpublished Schimper manuscript composed probably about 1832. There Schimper considered a theory of leaf placement he hardly even hinted at in print. Its most distinctive feature was his attempt to handle a biological phenomenon by means of an analogy drawn from physics. Each leaf was to be regarded as the peak of a "wave." The "wave" encompasses two to three revolutions of the stem, its declining edge consisting of exactly one revolution and its ascending edge exceeding one revolution to the extent of the leaf divergence. In a formation of 5/8, the descent would be 8/8 and the ascent 13/8. Schimper had, as usual, coined a lot of fancy new terminology to describe his ideas; the divergence, for example, he referred to as an "enthesis." As in his earlier article, Schimper viewed the fractions of the series as expressing a "reconciliation" between two conflicting forces; and he constructed several secondary series similar to those in Braun's paper. The prosentheses, which he described later at Stuttgart, were also discussed. The argument unfolded at an extremely idealized level, exhibiting a more definite inclination to Naturphilosophie than did any of the published papers.76 The terminology is a particular curiosity; the enthesis and prosenthesis are oddly reminiscent of Hegel's thesis and antithesis. Confronted with a cooperative research effort, one's natural response is to ask about the relative share of each scientist in developing the theory. Braun was more vocal on this point than Schimper; publicly he always attributed the basic ideas to his older friend, depicting himself as the subordinate fellow worker. Nevertheless, his public discussion of this question never got down to details, and his private opinion seems to have been somewhat different. Roper, not Schimper, inspired his original interest in phyllotaxis. As for the development of the spiral theory, a manuscript memoir Braun wrote in 1835 attributed substantial credit to himself. In this account Braun was first led by Schimper to reduce all leaf formations to 76. Jost, "Eine unbekannte Schrift," pp. 309-313.

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The Spiral Theory of Phyllotaxis whorls.77 This was also Roper's approach to flower structures.78 Braun defended this position against Martius's spiral idea in a talk delivered in January 1828.79 At the same time, though, he developed the fractional method of representing leaf divergence; and in August 1828 his study of pine cones sparked the realization that all the scales could be represented as belonging to a single spiral. Typically, it was Schimper who christened Braun's idea with the term divergence. More significantly, Schimper made the discovery that many of the most common divergences could be arranged in the order of the Fibonacci series.80 I have no reason to question that account; the proper verdict seems to be that the spiral theory was truly a joint creation. Braun's reluctance to advance this claim publicly I ascribe to the attitude of deference that marked his relationship to Schimper in the early years of their friendship and to the fact that Braun's fractional technique for representing divergence naturally loomed smaller in his own eyes than Schimper's spectacular innovation. On the other hand, Braun contributed more than his share to the clarity and public reputation of the idea. Evaluating the intrinsic merit of the theory itself is equally complicated. Botanists today agree with Schimper and Braun that there is a remarkable correspondence between leaf divergences and the values of the Fibonacci series or, less commonly, of the related series lying between 1/3 and 1/4. However, in keeping with the modern probabilistic methods of science, they prefer to treat this correspondence as statistical rather than absolute. Furthermore, they agree with the Bravais brothers in considering this a distribution around the limits of these series rather than their individual fractions81-a view Bonnet anticipated to some extent by his observation that each cycle of the quincunx is slightly twisted, blurring the exactness of the distribution. If durability is an acceptable argument, the main proposition of the spiral theory has held up fairly well. But perhaps more interesting are those portions of the theory which have been completely rejected, particularly Braun's secondary series and Schimper's prosentheses. Why did the discoverers try to cover the exceptional cases and 77. Ibid., p. 323. 78. Rbper, "Observations," pp. 436-438. 79. Alexander Braun to his parents, January "Alexander Braun," p. 54. 80. Jost, "Eine unbekannte Schrift," pp. 323-324. 81. Snow, "Problems of Phyllotaxis," p. 194.

10, 1828, (Mettenius),

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boundary regions within their purview by such lame contrivances? What was the "arbitrarily handled theory of abortion" they were so determined to combat? The exaggerated vigor with which Braun and Schimper rejected the idea of accident in plant form was probably aimed at certain trends in the Naturphilosophie of their day. In searching for ideal norms of plant form, botanists like Christian Nees von Esenbeck, Heinrich Link, and Gottlieb Bischoff made liberal use of the term "deformation" (Missbildung) to describe forms they considered incomplete (Unvollkommen). Teratology, an expression coined by Geoffrey Saint-Hilaire for the study of abnormalities, had become extremely popular. In botany this fad can be partly traced to the influence of de Candolle, who made it a key element in his morphology.82 In order to establish criteria for a natural system, de Candolle postulated a "symmetry" in plant form. According to this notion of symmetry, the true type of a plant is to be determined by the relative position of its organs. This is comparable among species and genera, enabling the systemist to make his decision. However, de Candolle had observed a difficulty in that the basic symmetry of some species is obscured by what he referred to as the regular abortion of certain organs. The abortion is not complete though; some signs are always accessible to the eye of the astute observer.83 There is something unsatisfactorily paradoxical about a "'regular abortion." In their groping toward the principle of homology, the botanists of the 1820's were employing an unsuitable conceptual framework. Braun and Schimper were not the only objectors either. Goethe, for example, complained about de Candolle: . . . (he) assumes a certain regularity on the part of nature, and everything that fails to coincide with it he calls abnormalities and deviations, which-through abortion, extraordinary development, atrophy, or amalgamation-mask and conceal the basic principle. In contrast, Goethe defended his own outlook: Metamorphosis is a higher concept-it governs the regu82. Emmanuel Radl, Geschichte der biologischen Theorien, 2nd ed. (Berlin: Wilhelm Engelmann, 1913), Vol. I, pp. 330-333. Adolf Hansen, Goethes Metamorphose der Pflanzen. Geschichte einen botanischen Hypothese, pt. 1 (Giessen: Alfred Topelmann, 1907), 123, 138-142. 83. Augustin P. de Candolle, Theorie elementaire de la botanique, 2nd ed. (Paris: Deterville, 1819), pp. 88-105.

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The Spiral Theory of Phyllotaxis lar and the irregular; it explains the formation of the single rose as well as the double one, the production of the common tulip as well as the rarest orchid.84 Braun and Schimper, then, were defending their notion of metamorphosis against what seemed to them an unjustified reliance on the idea of abortion.85 Unfortunately, in their campaign for regularity in plant form, they seized on some very clumsy weapons. Prosentheses and secondary series were even less help to botany than regular abortions. It should be remembered, however, that these two eccentric ideas are not central to the spiral theory and do not constitute a serious objection to it. The really important problem-one Braun and Schimper could not begin to solve-was explaining the basic reason for mathematical regularity in leaf arrangement. Their rather futile gestures in this direction deserve sympathy. The riddle was an extremely difficult one, and only recently has anyone made much progress toward solving it. In general, much of what appears as cloudy idealism in these papers was an effort to come to grips with problems that Braun and Schimper were simply not equipped to handle. They did the best they could with the intellectual tools at their disposal; and it seems fair to say that the handicaps of their idealist philosophy were quite outweighed by the inspiration it afforded toward their creative accomplishment. 84. J. W. Goethe, "The Influence of my Publication," Mueller (ed.), Writings, p. 211. 85. For a comparison of the spiral theory and symmetry from a somewhat different point of view, see Walter Baron, "Die idealistische Morphologie Al. Brauns und A. P. de Candolles und ihr Verhaltnis zur Deszendenzlehre," Beihefte zum Botanischen Centralblatt, 48 (1931), 328331.

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Humboldt,Darwin, and Population* FRANK N. EGERTON Division of Social Sciences University of Wisconsin-Parkside Kenosha, Wisconsin

INTRODUCTION Darwin's theory of evolution by natural selection was based in part upon a new perspective in population biology. In a previous article I attempted to describe the immediate steps leading to this perspective.' It was obvious that Charles Lyell had written an important synthesis on the subject to which Darwin was greatly indebted.2 My task seemed clear-to account for the sources of Lyell's ideas and then to show how Darwin built upon and went beyond them. Advances in the understanding of biogeography constituted part of the story, and Alexander von Humboldt was discussed only for his contributions to this subject.3 Furthermore, Darwin's Journal of 1. "Studies of Animal Populations from Lamarck to Darwin," J. Hist. Biol., 1 (1968), 225-259. Since its publication, two other papers have been published which have discussed the development of Darwin's ideas on population; neither paper discussed the important role of Humboldt. Robert M. Young, "Malthus and the Evolutionists: the Common Context of Biological and Social Theory," Past & Present, no. 43 (May 1969), 109-145 and Peter Vorzimmer, "Darwin, Malthus, the Theory of Natural Selection," J. Hist. Ideas, 30 (October 1969), 527-542. 2. Charles Lyell, Principles of Geology, Being an Attempt to Explain the Former Changes of the Earth's Surface, by Reference to Causes Now in Operation, 3 vols. (London: John Murray, 1830-33), vol. II. 3. Alexander von Humboldt and Aim6 Bonpland, Essai sur la g6ographie des plantes; accompagn6 d'un tableau physique des regions 6quinoxiales, fond6 sur des mesures executtes, depuis le dixiAme degni de latitude borgale jusqu'au dixiAme degrn de latitude australe, pendant les annUes 1799, 1800, 1801, 1802 et 1803 (Paris: Levrault, Schoell, 1807 [dated 1805]; complete facsimile ed., Mexico City: Institut Panam6ricain de Giographie et d'Histoire, 1955). * An abridged version of this paper was presented at the meeting of the History of Science Society in Washington, D.C., on 29 December 1969. Journal of the History of Biology, vol. 3, no. 2 (Fall 1970), pp. 325-360.

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Researches (1839; 2nd ed., 1845, retitled Voyage of the Beagle) was only briefly discussed because the numerous accounts of population in it were not synthesized into a biological theory, and they did not seem to represent an advance beyond Lyell's contribution. Subsequently, a comparative study of Darwin's Journal of Researches and Humboldt's Personal Narrative of travels in America has convinced me that a major influence was omitted from my previous account.4 Humboldt seems to have been as significant an influence upon Darwin as was Lyell. This conclusion is based upon three points: (1) Humboldt made major contributions to the relevant topics; (2) Darwin read Humboldt before he read Lyell; and (3) Lyell also read Humboldt and benefited from Humboldt's contributions. This re-evaluation of influences does not, however, substantially alter the assessments I made in my previous article concerning the importance of Lyell's and Darwin's contributions. I credited both of them with having made primarily synthetic contributions, and even though Humboldt's writings undoubtedly assisted them in their tasks more than previously indicated, the syntheses nevertheless remain the achievements of Lyell and Darwin.5 Each penetrated enigmas that Humboldt left unexplained. Each did so with information not available to Humboldt when he wrote his Personal Narrative, but which became available while he was still active. That Lyell and Darwin, but not Humboldt, wrote The Principles of Geology and The Origin of Species is not to be explained primarily on the basis merely of information available. Other important factors were the attitudes and perspectives which they brought to bear upon the relevant problems. Humboldt ranged widely, but this prevented him from concentrating long enough upon 4. Humboldt, Voyage aux r,4gions 6quinoxiales de nouveau continent fait dans les ann,es 1799 d 1804 par Alexandre de Humboldt et Aime Bonpland: Relations historiques, 3 vols. (Paris: F. Schoell, 1814-19). For this study I have used Williams' English translation, which is far from ideal, but the one Darwin read. It is entitled Personal Narrative of Travels to the Equinoctial Regions of the New Continent, during the Years 1799-1804, by Alexander de Humboldt, and Aim6 Bonpland; with Maps, Plans, &c. Trans. Helen Maria Williams, 7 vols. (London: Longman, Hurst, Rees, Orme, and Brown, 1814-29; facsimile ed., New York: AMS Press, 1966 [hereafter cited as PN]). The vols. I have used are dated as follows: I: 3rd ed., 1822; II: 3rd ed., 1822; III: 2nd ed., 1822; IV: 1st ed., 1819; V: 1st ed., 1821; VI: 1st ed., 1826; VII: 1st ed., 1829. 5. This reference is to Darwin's Origin of Species, not his Journal of Researches.

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Humboldt, Darwin, and Population a subject to achieve the great scientific generalizations that he sought. Although Humboldt's influence upon Darwin is apparent upon comparison of their travel books, it is not especially obvious if one reads only Darwin's Journal of Researches. This was not because Darwin avoided mention of Humboldt -I find 23 references to him, though none are indexed-but because citations of factual material do not always convey adequately the extent of influence.6 In one footnote Darwin indicated that he considered Humboldt the foremost American traveler, but in this comment he only expressed the consensus.7 Darwin was later to cite in The Descent of Man Humboldt's Personal Narrative, but once again the references leave no impression of significant intellectual debt.8 The case is otherwise when one reads Darwin's Autobiography, which he mainly composed in May to August 1876, and which was published posthumously in 1887: During my last year at Cambridge [1830-31] I read with care and profound interest Humboldt's Personal Narrative. This work and Sir J. Herschel's Introduction to the Study of Natural Philosophy stirred up in me a burning zeal to add even the most humble contribution to the noble structure of Natural Science. No one or a dozen other books influenced me nearly so much as these two. I copied out from 6. Charles Darwin, Journal of Researches into the Geology and Natural History of the Various Countries Visited by H. M. S. Beagle, Under the Command of Captain Fitzroy, R. N. from 1832 to 1836 (London: Henry Colburn, 1839; citations from facsimile ed., New York, London: Hafner, 1952 [hereafter cited as JR]). He cited Humboldt without a reference on pp. 24, 36, 110, 288, 293, 361, 449, 471. He also cited Humboldt's works as follows: Personal Narrative was cited on pp. 12, 18, 331, 431, 432, 627; Political Essay on the Kingdom of New Spain was cited on pp. 152, 347, 447, 520, 521; Fragmens de g6ologie et climatologie asiatiques, 2 vols. (Paris, 1831) was cited on pp. 103, 274, 295; as quoted in Cuvier's Theory of the Earth, cited on pp. 614-615. Darwin also mentioned without reference Aime Bonpland, p. 164. 7. JR, p. 110. Humboldt, in turn, used and praised Darwin's writings. Humboldt, Kosmos. Entwurf einer physischen Weltbeschreibung, 5 vols., (Stuttgart, Tiibingen, 1845-62). Citations from English trans. by E. C. Ott6, assisted by B. H. Paul (in vol. IV) and W. S. Dallas (in vol. V), Cosmos: a Sketch of a Physical Description of the Universe, 5 vols., (London: Henry G. Bohn, 1849-58), I, 221, 237, 286, 297, 302, 315, 338; II, 437; V, 288, 389. 8. Darwin, The Descent of Man, and Selection in Relation to Sex (London: John Murray, 1871; 2nd ed., 1874; citations from Modern Library ed., New York, 1936), chap. 3, n. 28; chap. 7, p. 542; chap. 19, nn. 43 and 69.

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Humboldt long passages about Teneriffe, and read them aloud.9

Humboldt's accounts aroused a strong desire in Darwin to make a similar scientific journey, and he hoped to persuade one or more of his friends to join him. On 11 July 1831 he wrote to Professor John Stevens Henslow: "I hope you continue to fan your Canary [Islands] ardor: I read & reread Humboldt; do you do the same, & I am sure that nothing will prevent us seeing the great Dragon Tree [of Teneriffe]." 10 When his dream was realized in the voyage of the Beagle, Darwin wrote Henslow that "at Santa Cruz, whilst looking amongst the clouds for the Peak," he repeated to himself "Humboldt's sublime descriptions." After exploring a Brazilian jungle he wrote: "I formerly admired Humboldt, I now almost adore him; he alone gives any notion of the feelings which are raised in the mind on first entering the Tropics." 11 These glowing tributes have been noted by a number of scholars, but Darwin's very enthusiasm in these passages gives the impression that he derived much more inspiration than education from reading Humboldt. An extended documentation and evaluation of Humboldt's influence upon Darwin is needed, and the present paper attempts to fill this need for 9. The Autobiography of Charles Darwin, 1809-1882, with Original Omissions Restored, ed. Nora Barlow (New York: Harcourt, Brace, 1959), pp. 67-68. On 4 August 1881 Hooker wrote to Darwin and asked: "Now will you give me your idea as to whether I should be right in calling Humboldt the greatest of scientific travellers, or only the most accomplished,-or most prolific?" To which Darwin replied on 6 August 1881: "I believe that you are fully right in calling Humboldt the greatest scientific traveller who ever lived, I have lately read two or three volume again. His Geology is funny stuff; but that merely means that he was not in advance of his age. I should say he was wonderful, more for his near approach to omniscience than for originality." Life and Letters of Sir Joseph Dalton Hooker O.M., G.C.S.I., Based on Materials Collected and Arranged by Lady Hooker, ed. Leonard Huxley, 2 vols. (London: John Murray, 1918), II, 223. The Life and Letters of Charles Darwin, including an Autobiographical Chapter, ed. Francis Darwin, 3 vols. (London: John Murray, 1887; citation from American ed., 2 vols. New York: D. Appleton, 1887), II, 422. See also Jean Th6odorids, "Humboldt and England," British J. Hist. Sci., 3 (1966), 39-55. Idem, "Humboldt et Darwin," Actes du XI' Congr&s internat. Hist. Sci., 5 (1968), 87-92. Darwin's remarks on Humboldt's geology probably refers only to the PeTsonal Narrative, and not to A Geognostical Essay (cited below, n. 103). 10. Darwin and Henslow, the Growth of an Idea. Letters 1831-1860, ed. Nora Barlow (London, Berkeley, Los Angeles: John Murray, University of California, 1967), p. 26. Darwin later wrote a letter of appreciation to Humboldt; the latter's reply of 18 September 1839 is quoted on p. 26, n. 2. 11. Ibid., pp. 53, 55. Dated 18 May 1832.

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Humboldt, Darwin, and Population population biology and related topics. Before turning to specific examples, however, it seems desirable to compare and contrast their travel books generally. Both books have the same basic organization; they describe the places, climate, natural resources, agriculture, mining, people,12 political situation, and various objects as encountered, with topical discussions embedded where most appropriate. For example, particular plants and animals or particular farming practices might be found at a number of places, but were usually discussed in detail either where first seen or where the encounter was most significant; elsewhere in the narrative, where relevant, the reader was referred to this account. Both authors directed their books toward both the scientist and the general reader. The authors were concerned not to bore the latter with too many scientific details (but many more such details were included than would likely appear in a twentiethcentury counterpart of their books). Some detailed scientific accounts they relegated to monographs on which they invited scientific specialists to work. Both authors referred to earlier scientific and travel literature where appropriate. Both described selected personal experiences and people encountered, and they reacted to the people as individuals rather than as representatives of some group, such as priests or government officials. In spite of many vexations while traveling, each author wrote in a pleasant tone and showed generosity in judging others. Both espoused liberal ideals, praised democratic institutions, and condemned slavery and tyranny when encountered. It can be argued that the above attributes are also found in other travel books by naturalists of the period, and that therefore the similarities arise because both followed a common tradition rather than that Darwin followed Humboldt specifically. This argument deserves mention because each of them did study other travel literature. Indeed, Humboldt was strongly influenced by the excellent model provided by his "celebrated teacher and friend, George Forster. Through him 12. Erwin H. Ackerknecht, "George Forster, Alexander von Humboldt and Ethnology," Isis, 46 (1955), 83-95. Pierre Huard and Jean Th6odoridbs, "Humboldt et l'anthropologie," Sudhoifs Archiv Gesch. Med. Naturwiss, 46 (1962), 69-81. A number of studies on Humboldt have appeared since I submitted this paper for publication. Two of these of particular relevance are: Charles Minguet, Alexandre de Humboldt, Historien et G&Ographe de l'Am&ique espagnole (1799-1804) (Paris: Frangois Maspero, 1969) and Heinrich Pfeiffer, ed., Alexander von Humboldt: Werk und Weltgeltung (Munich: R. Peper, 1969).

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began a new era of scientific voyages, the aim of which was to arrive at a knowledge of the comparative history and geography of different countries," 13 which Forster presented in his Voyage round the World (1777).14 But it was Humboldt's Personal Narrative that profoundly influenced Darwin and served as a pattern for his Journal of Researches. Other travel literature he consulted for the sake of gathering information. The contrasts between Humboldt's and Darwin's books seem much less significant than the similarities. The most striking difference is in their length. Darwin's Journal of Researches was not short; it has 630 pages, with about 224,000 words.-' But Humboldt's Personal Narrative, in the first English translation, is in seven volumes which have a total of 3992 pages with about 917,700 words-about four times longer than Darwin's book. Humboldt traveled in northern South America, Mexico, and Cuba; Darwin traveled in southern South America, as part of a global voyage. Their paths intersected only at the Canary Islands and Lima, Peru. Had their paths crossed more often, Darwin would undoubtedly have cited Humboldt even more often. Latin America, when Humboldt visited it in 1799-1804, had been under Spanish rule, but at the time of Darwin's visit, 1832-1835, it had gained its independence.1" Humboldt was inclined to discuss the economic conditions of the countries he visited in much greater detail than Darwin, and he also discussed extensively, though Darwin did not, the native languages.17 Darwin may not have paid close attention to Humboldt's linguistic discussions, but he could have noticed that there is an interesting parallel between the evolution and geography of languages and of biological species. Languages, like species, spread when a population either expands or otherwise migrates from one area to another, and in new locations both are apt to diverge from those found in the place 13. Humboldt, Cosmos, II, 436. 14. Forster (1754-94), A Voyage Round the World, in His Britannic Majesty's Sloop, Resolution, Commanded by Capt. James Cook, dutring the Years 1772, 3, 4, and 5, 2 vols. (London: B. White, J. Robson, P. Elmsly, G. Robinson, 1777; reprinted with introd. by Robert L. Kahn as vol. 1 of Georg Forsters Werke, Berlin: Akademie Verlag, 1968). 15. The revised ed. of 1845 had only about 213,000 words. These are Nora Barlow's estimates. R. B. Freeman, The Works of Charles Darwin: An Annotated Bibliographical Handlist (London: Dawsons of Pall Mall, 1965), p. 15. 16. But the Beagle did not return to England until 2 October 1836. 17. PN, III, 241-275, 299-303 et passim. But Darwin later discussed this point in The Origin of Species, 1st ed., p. 422, and in The Descent of Man, chap. 3.

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Humboldt, Darwin, and Population of origin. Just as divergent populations become varieties and eventually separate species, so divergent languages become dialects and eventually different languages. In both cases the newly separated entities have affinities that indicate their common origin. POPULATION When one turns to a comparison of their writings on population, one finds many similarities, but influence is a more complex matter than can be exhibited in parallel passages. This is particularly true when the subject is as broad in scope as is population, and when the one being influenced is an active thinker who shapes the contributions of others to meet his own needs, as did Darwin. The following discussion of population biology is divided into two parts-human and animal-though these are related, and neither Humboldt nor Darwin made a special point of separating them in their books. Ideas from one could and did seep over into the other. They are separated here for two reasons: (1) clarity of issues; and (2) to show that, although in human demography Darwin respectfully followed Humboldt's lead, in animal demography Darwin, aided by Lyell's outlook, went beyond Humboldt. Humboldt had an amazing breadth of knowledge. He mastered practically every existing science, including the social sciences, and he was probably the only person living in the nineteenth century to do so. He may have gained insight from Buffon's example of discussing aspects of both animal and human population biology, but given the breadth of Humboldt's interests, one imagines that he would have studied both subjects even if he had never read Buffon.18 The main stimulus for his demogarphic studies was probably the training in geography which he received in 1789-90 at the University of Goettingen,19 and that interest was most likely reinforced by the week he spent in 1797 with the renowned pioneer in public health, Dr. Johann Peter Frank.20 It seems probable that Humboldt's Personal Narrative was 18. 1 have discussed Buffon in my doctoral dissertation entitled "Observations and Studies of Animal Populations before 1860: A Survey Concluding with Darwin's Origin of Species" (Madison: University of Wisconsin, 1967), pp. 189-205, 259-262. 19. Ackerknecht, "Forster, Humboldt and Ethnology," pp. 83, 88, 91. 20. Hanno Beck, Alexander von Humboldt, 2 vols. (Wiesbaden: Franz Steiner, 1959-61), I, 96.

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responsible for inculcating in Darwin an interest in population and for encouraging Darwin to read Malthus. These two points form a central thesis of this paper. Why did Humboldt's book exert this influence? The answer seems to be as follows. First, as already shown, Darwin had a tremendous admiration for Humboldt. Second, Humboldt clearly believed that demographic knowledge was very important. Because of his admiration, Darwin accepted this judgment. But Darwin did not have a strong professional interest in economics, which was the framework of Humboldt's discussion. Humboldt must have aroused Darwin's interest in demography by repeatedly showing that, in spite of the importance of culture, the populations of men and domestic animals are significantly affected by some of the same environmental factors that affect wild animals. Having developed an interest in demography, Darwin must have read Malthus (whether he remembered it or not) on Humboldt's recommendation-not by chance as he later implied: "I happened to read for amusement Malthus on Population." 21 Furthermore, Darwin's unshakable confidence in Malthus' theory just at the time of widespread criticism must have been, to some extent, due to Humbold't endorsement.22 Human Demography Although Humboldt strongly endorsed Malthus, he was not himself a Malthusian. And to make this curious situation worse, he failed to make explicit (if he knew) the extent of his disagreement. Malthus' thesis was that population always grows faster than subsistence, and therefore there is always overpopulation.23 Humboldt evidently felt that Malthus was astute 21. Darwin, Autobiography, p. 120. 22. William Price Albrecht, William Hazlitt and the Malthusian Controversy (Albuquerque: University of New Mexico, 1950). J. A. Banks and David V. Glass, "A List of Books, Pamphlets, and Articles on the Population Question, published in Britain in the Period 1793 to 1880," in Introduction to Malthus, ed. David V. Glass (London, New York: Watts, John Wiley and Sons, 1953), pp. 79-112. Harold A. Boner, Hungry Generations: The Nineteenth-Century Case Against Malthusianism (New York: King's Crown Press, 1955). Marx and Engels on Malthus, ed. Ronald L. Meek (New York: International Publishers, 1954). Kenneth Smith, The Malthusian Controversy (London: Routledge and Kegan Paul, 1951). Kingsley Davis, "Malthus and the Theory of Population," in The Language of Social Research, ed. Paul F. Larzarsfeld and Morris Rosenberg (Glencoe: Free Press, 1955), pp. 540-553, p. 588nn. 23. Thomas Robert Malthus, An Essay on the Principle of Population; or, a View of Its Past and Present Effects on Human Happiness; with an

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Humboldt, Darwin, and Population for having clarified the danger of overpopulation, but that this danger was not as likely as Malthus believed. In his Political Essay on the Kingdom of New Spain (1811) he wrote that Malthus' Essay on the Principle of Population was "one of the most profound works in political economy which has ever appeared." 24 Humboldt's reservations were indicated while yet voicing praise: The Canary islands are still remote from feeling the evils that arise from too considerable a population, and of which Mr. Malthus has unfolded the causes with so much precision and knowledge. The misery of the people has considerably diminished since the cultivation of potatoes has been introduced, and since they have begun to sow more maize than wheat and barley.25 Humboldt's reservations appeared even more pronounced in the volume published a few years later, but this time it may have been only the disciples of Malthus, and not the master himself, with whom Humboldt wished to part company. In disagreeing with some earlier estimates of the growth rates of American countries, he remarked: "These numbers, I confess, do not affright me from the motives that would alarm the zealous disciples of the system of Malthus." 26 That he was not a zealous Malthusian is also clear from his frequent laments over the sparse population in South America.27 He strongly condemned infanticide and abortion among the Indians and felt no inclination to justify these practices on Malthusian grounds. He was also relieved that the abortive drinks of the Indians were unknown in Europe.28 Inquiry into Our Prospects Respecting the Future Removal or Mitigation of the Evils which It Occasions, 2nd ed. (London: J. Johnson, 1803), chaps. 1-2. 24. Humboldt, Essai politique sur le Royaume de la Nouvelle Espagne, 2 vols. (Paris, 1811). All citations are from the English translation, which was used by Darwin, entitled Political Essay on the Kingdom of New Spain trans. John Black, 4 vols. (London, Edinburgh: Longman, Hurst, Rees, Orme, and Brown; H. Colburn; W. Blackwood; Brown and Crombie, 1811; facsimile ed., New York: AMS Press, 1966), I, chap. 4, p. 107. 25. PN, I, 292. 26. PN, VI, 121. For his explanation of the slower growth rate, see the quotation below, n. 44. 27. E.g.: "The imperfection of political institutions may for ages have converted places, where the commerce of the world should be found concentrated, into deserts; but the time approaches when these obstacles will exist no longer" (PN, V, 513). See also many of the above quotations. 28. "We may congratulate the civilized nations of Europe, that they have

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One biographer, Keilner, recently suggested that Humboldt was "following the procedure of Malthus," when "he prepared a lst of the excess of births over deaths in those countries of which figures could be obtained, and related the rate of mortality to the climatic conditions of the district." 29 This statement is true in the sense that both Malthus and Humboldt carried out some investigations in statistical demography. But it is unlikely that Malthus had much, if any, influence upon Humboldt's demographic researches. The first edition of Malthus' Essay (1798) contained few statistical data (primarily in chap. 7), and Humboldt had already completed his own demographic researches (but not his writing) when Malthus published the much longer second edition (2 vols., 1803). Even in Malthus' second edition there were no statistical innovations, and it is difficult to see what Humboldt might have found applicable for his own reports, since the rate of population increase would have been essential to his economic outlook, even if he had never heard of Malthus.30 Humboldt wrote extensively and capably about New World populations, always being mindful of the political and economic context. He evaluated both the actual and potential resources of the regions he visited. He constantly speculated upon how the wealth and population of various areas could be increased -by clearing away the forests, by persuading the Indians to become farmers instead of nomadic hunters, by planting different crops, by permitting trade with non-Spanish colonies, and by many other means. He was not always able to provide either a thorough analysis of the problems or infallible solutions, but he tried to avoid superficial judgments. When he hitherto had no knowledge of ecbolics in appearance so little injurious to health. The introduction of these drinks would perhaps increase the depravity of manners in towns, where one quarter of the children see the light only to be abandoned by their parents" (PN, V, 32). On this practice, see George Devereux, A Study of Abortion in Primitive Societies. A Typological, Distributional, and Dynamic Analysis of the Prevention of Birth in 400 Preindustrial Societies (London and New York: T. Yoseloff and Julian Press, 1960), pp. 37, 179, 197, 304. 29. Charlotte (Mrs. L.) Keilner, Alexander von Humboldt (London, New York, Toronto: Oxford University Press, 1963), p. 103. 30. Malthus' statistical abilities were rated low by Harald Westergaard, Contributions to the History of Statistics (London: P. S. King and Son, 1932; facsimile edition, New York: Ogathon Press, 1968), pp. 125-129. A more detailed, but not more favorable, analysis has recently been made by Michael Drake, "Malthus on Norway," Population Studies, 20 (1966), 175-196. Idem, Population and Society in Norway, 1735-1865 (Cambridge: The University Press, 1969), chap. 2.

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Humboldt, Darwin, and Population could get them, he published extensive population statistics, these being germane to his economic description of a region and also a means of substantiating his demographic comments. Darwin, though less at home in discussing economics than was Humboldt, nevertheless made similar assessments: Considering the enormous area of Brazil, the proportion of cultivated ground can scarcely be considered as anything, compared to that which is left in the state of nature: at some future age, how vast a population it will support!3' Population statistics were not as essential to Darwin's as to Humboldt's discussion, but since Darwin was impressed with their importance, he provided them when he could.32 Since Humboldt was not writing a general treatise on population, he did not discuss fertility extensively. He was certainly aware, however, that the potentials for human population increase were much greater than what occurred. He accepted Benjamin Franklin's claim (1755), as publicized by Malthus, that the English in America could double their population in 25 years.33 Data which Humboldt had on Latin America indicated, however, that its growth was not so rapid.34 He also knew that the rate of population growth in Europe was considerably slower than in the New World.35 The relative population of the different races at a given locale was something Humboldt almost always discussed.36 Perhaps he knew of Franklin's opposition to admitting nonEnglish people into the English colonies. Franklin believed 3 1. JR, p. 27. 32. JR, p. 140: Buenos Ayres-60,000, Monte Video-15,000; p. 337: Chiloe-42,000; p. 421: Coquimbo-6000 to 8000; p. 516: Sydney-23,000; p. 533: Hobart Town-13,826, Tasmania-36,505; p. 570: Port Louis20,000; p. 575: Cape Town-15,000, South Africa-200,000; p. 580: St. Helena Island-about 5000; p. 594: Angra-about 10,000. 33. PN, VI, 116. Benjamin Franklin, "Observations concerning the Increase of Mankind, Peopling of Countries, &c.," anonymous appendix in William Clarke, Observations on the Late and Present Conduct of the French, with Regard to Their Encroachments upon the British Colonies in North America (Boston, 1755); reprinted in The Writings of Benjamin Franklin, ed. Albert Henry Smyth, 10 vols. (New York, London: Macmillan, 1905-7), III, 63-73. Franklin's estimate proved to be excellent, as indicated by the censuses taken from 1790-1890. Conway Zirkle, "Benjamin Franklin, Thomas Malthus and the United States Census," Isis, 48 (1957), 58-62. 34. PN, VI, 121-122. 35. New Spain, I, chap. 4, pp. 106-107. See also PN, I, 288. 36. E.g., PN, III, 326, 430, 435-438, 444; VI, 129-142. New Spain, I, chap. 6, p. 131; chap. 7, p. 256.

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that those people, whether Negro slaves or Europeans, were inferior to the English, and that the English could easily populate the North American continent without assistance from others.37 It is doubtful that Humboldt, a German, would have agreed with this; I detect no racial bigotry in his writing. There were two basic reasons why he considered the racial composition of a population important. The first was that political and military loyalties tended to be racially determined. The Negro slaves of Haiti had already revolted and taken control of that island, and he suspected that the continuation of slavery would lead to similar uprisings elsewhere. The second reason was that he found that races tended to differ in economic productivity. He was prepared to admit, however, that a race might be somewhat modified in its characteristics by the place in which it lived: The Spaniards transplanted to the torrid zone having become under new skies strangers to the remembrances of their mother country, must have felt more sensible changes than the Greeks, settled on the coasts of Asia Minor and of Italy, the climates of which differ so little from those of Athens and Corinth. It cannot be denied that the character of the Spanish Americans has received different modifications from the physical constitution of the country.38 Darwin rightly felt that Humboldt had collected useful prognostic data in his racial statistics, and he followed his example: In the same census of 1832 there were in Chiloe and its dependencies forty-two thousand souls. The greater number of these appear to be little copper-coloured men of mixed blood. Eleven thousand actually retain their Indian sumame; but it is probable that not nearly all of them are of pure blood. Their manner of life is the same with that of the other poor inhabitants, and they are all Christians: but it is said that they yet retain some strange superstitious ceremonies, and that they pretend to hold communication with the devil in certain caves. Formerly, every one convicted of this offence was sent to the Inquisition at Lima. Many of those people who are not included in the eleven thousand cannot be distinguished by their appearance from Indians. Gomez, the governor of Lemuy, is descended from noblemen 37. Franklin, "Observations," par. 13, 22-24. Franklin did not reprint par. 23-24 after the 1755 edition. 38. PN, III, 426-427. Cf. New Spain, chap. 6-7.

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Humboldt, Darwin, and Population of Spain on both sides, but by constant intermarriages with natives, the present man is an Indian. On the other hand, the governor of Quinchao boasts much of his pure Spanish blood.39 On the island of Chileo miscegenation may have occurred without serious strife, but in many places racial antagonism was evident. At Bahia Blanca when Darwin exclaimed against the army's massacre of the Indians, the reply was: "Why, what can be done? they breed so !"40 It was evident in these accounts by Humboldt and Darwin that there was a struggle between the races, in which the weaker race was subjugated and perhaps even exterminated. Once Darwin stated this explicitly: "The varieties of man seem to act on each other in the same way as different species of animals-the stronger always extirpating the weaker."41 But because the situations were usually revolting, moral indignation often inhibited scientific curiosity, and this kind of struggle usually elicited from both Humboldt and Darwin social, economic, or moral, rather than biological commentary. In view of the importance of competition or struggle for Darwin's subsequent theory of evolution, it seems worthwhile to distinguish three kinds of human struggle that he and Humboldt met with in South America, even though neither of them explicitly did so.42 One was between the races within the same civilization, as discussed above. A second was the struggle of an individual against nature, such as the several accounts which greatly impressed Humboldt, of men and women who had managed to escape from crocodiles which had snatched them from the banks of rivers.43 The third kind of struggle was the totality of the individual struggles that comprised the second kind. The distinction may seem trivial, but it is distinct from the second because whether or not a population flourishes is not indicated by the fate of some individual who may have been 39. JR, p. 337. 40. JR, p. 120. 41. JR, p. 520. Darwin later cited Humboldt under the heading of "On the Extinction of the Races of Man" in The Descent of Man, chap. 7. 42. Competition refers to the attempt of two or more organisms to acquire the same thing, such as light, water, food, or shelter. Darwin liked to use the term "struggle," which includes competition, but also includes the struggle of an organism against his inanimate environment and the struggle between predator and prey. See L. C. Birch, "The Meanings of Competition," American Naturalist, 91 (1957), 5-18. See also below, n. 73. 43. PN, IV, 423-424. See V, 706-707. Crocodiles are discussed below.

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observed, but whose fate was atypical. Both Humboldt and Darwin remarked upon these kinds of struggle because they visited places where such struggles were conspicuous. In one suggestive passage Humboldt raised the question of natural selection only to let it drop: We might be tempted to think that made and vigorous, because feeble want of care; and that the strongest causes cannot act on the Indians of the manners of our peasants.44

savages all appear well children die young for alone survive: but these the Missions, who have

Darwin was most impressed by the harshness of the situation of the Fuegian Indians at the southern extremity of South America: At night, five or six human beings, naked and scarcely protected from the wind and rain of this tempestuous climate, sleep on the wet ground coiled up like animals. Whenever it is low water they must rise to pick shell-fish from the rocks; and the women, winter and summer, either dive to collect sea eggs, or sit patiently in their canoes and with a baited hair-line jerk out small fish. If a seal is killed, or the floating carcass of a putrid whale discovered, it is a feast: such miserable food is assisted by a few tasteless berries and fungi. Nor are they exempt from famine, and, as a consequence, cannibalism accompanied by parricide.45 Although they did not have to withstand the invasion of Europeans, each tribe was "surrounded by other hostile ones, speaking different dialects; and the cause of their warfare would appear to be the means of subsistence." "There is no reason to believe that the Fuegians decrease in number . . . Nature by making habit omnipotent, and its effects hereditary, has fitted the Fuegian to the climate and the productions of his country." 46

The overall picture which Humboldt presented of South 44. PN, III, 234. In a later volume, VI, 61, Humboldt observed: "What we have seen of the power of man struggling against the force of nature in Gaul, in Germany, and recently, but still beyond the tropics, in the United States, can scarcely give any just measure of what we must expect from the progress of civilization in the torrid zone." These two passages were not cited in the survey by Conway Zirkle, "Natural Selection Before the 'Origin of Species,'" Proc. Amer. Philos. Soc., 84 (1941), 71-123. 45. JR, p. 236. 46. JR, p. 237.

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Humboldt, Darwin, and Population America portrayed its civilization as struggling against a wide range of obstacles. Usually civilization succeeded, though sometimes only slowly.47 When it failed, Humboldt usually detected political and economic mismanagement.48 The emphasis which Humboldt placed upon the political and economic management of colonies as being essential to their welfare was not lost upon Darwin, who often expressed the same kinds of judgments in his Journal of Researches. Darwin was not generally censorious of the Latin Americans. If he deplored the Argentine campaigns to exterminate the Indians, he also condemned his countrymen for having been responsible for the decimation of the aborigines of New Zealand and Australia.49 He did believe, however, that the English had been much better colonizers than the Spanish or the French.50

Some causes of human mortality-open conflict between societies, the predation of wild animals, and infanticide-have already been discussed. Others that Humboldt encountered were poor diet,51 famine,52 diseases, and earthquakes. The last of these, of course, occurs only in certain areas of the world, but regions of South America are foremost among them. In a long discussion of earthquakes, Humboldt described the destruction which they had caused to life and property.53 Darwin confirmed Humboldt's accounts through personal experi47. For example: "The town of Cariaco has been repeatedly sacked in former times by the Caribs. Its population has agumented rapidly, since the provincial authorities, in spite of the prohibitory orders of the court of Madrid, have often favoured the trade with foreign colonies. The population has doubled in ten years and amounted, in 1800, to more than 6000 souls. The inhabitants are active in the cultivation of cotton" (PN, III, 191). 48. For example: "The same spirit of monoply has shut up the Meta, the Rio Atracto, and the river of Amazons. Strange policy that, which teaches mother-countries to leave those regions uncultivated where nature has deposited all the germs of fertility! The wild Indians have every where availed themselves of this want of population. They have dawn near the rivers, they molest the passengers, and attempt to reconquer what they have lost for so many ages" (PN, IV, 567). 49. JR, pp. 520-521, 533-534. 50. Sydney, Australia "is a most magnificent testimony to the power of the British nation. Here, in a less promising country, scores of years have effected many times more, than the same number of centuries have done in South America" (JR, p. 515). The French and English in Mauritius were contrasted in JR, pp. 571-572. 51. PN, II, 194. 52. New Spain, I, chap. 5, pp. 121-123. 53. PN, III, 445; IV, 3, 36. In the earthquake of 26 March 1812, many of Humboldt's friends were among the 12,000 inhabitants killed in Caracas.

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ence. He landed at Concepcion two weeks after it had been destroyed by an earthquake, and he suspected that if it had struck during the night instead of at midday, the mortality would have been many thousands rather than less than one hundred. He was much impressed by the material damage which occurred, and he concluded that "earthquakes alone are sufficient to destroy the prosperity of any country." 54 The importance of disease as a mortality factor was a matter of common experience, but the causes of diseases remained one of the great mysteries of nature. Though Humboldt was not a physician, his scientific interests encompassed diseases. He read widely in medicine and brought to this subject his outstanding scientific judgment.55 His discussions were sensible and cautious, but the evidence was insufficient to enable him to significantly clarify the etiology of diseases. He attempted to collect information on the history of diseases in America, but the information was scant and in many cases did not permit a definite identification.56 For present purposes there is no need to dwell upon Humboldt's speculations concerning etiology, but one of them is worth quoting both for being a good guess that was not followed up and for showing how animal demography could be related to human demography. He asked, "Do the moschettoes themselves increase the insalubrity of the atmosphere?" It seemed probable, on the one hand, that these insects were merely attracted to locations that were unhealthy to man, in which case there would be no causal connection. On the other hand, when one reflected that a cubic foot of air is often peopled by a million of [these] winged insects which contain a caustic and venomous liquid . . . we are led to inquire whether the presence of so many animal substances in the air must not occasion particular 54. JR, pp. 371-373. 55. Heinrich Schipperges, "Humboldts Beitrag zur Medizin des 18. Jahrhunderts," in Alexander von Humboldt. Studien zu seiner universalen Geisteshaltung, ed. Joachim Heinrich Schultze (Berlin: Walter de Gruyter, 1959), pp. 36-68. Idem, "Quellen zu Humboldts medizinischem Weltbild," Sudhoffs Archiv Gesch. Med. Naturwiss., 43 (1959), 147-171. Idem, "Alexander von Humboldt und die Medizin seiner Zeit," Archiv fiur Kulturgeschichte. 41 (1959), 166-182. 56. The glossary by Phyllis Richmond is of some help in equating Humboldt's names of diseases with modern names, but this does not answer the question of whether the diseases were consistently diagnosed under the same name in the first place. Phyllis A. Richmond, "Glossary of Historical Fever Terminology," J. Hist. Med., 16 (1961), 76-77.

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Humboldt, Darwin, and Population miasmata. I think that these substances act on the atmosphere differently from sand and dust; but it will be prudent to affirm nothing on this subject.57 He had to leave this question unanswered, as did Darwin, who in the same cautious spirit offered observations that he hoped might help dispel the mystery of contagion. Neither of his discussions of "miasma" was very extensive, but in both he cited Humboldt's observations.58 The theoretical framework for investigating the etiology of disease was ecological, and this being the case, Darwin must have felt that there was no better authority that he could cite on diseases in America than Humboldt. Animal Demography Humboldt As mentioned above, Humboldt had an interest in all the sciences and social sciences, and although his contributions to zoology were less extensive than to some other sciences, they were nevertheless noteworthy.59 His observations on animal demography were thus one aspect of a general interest in biology. However, when discussing animal demography he usually had uppermost in his mind the relation of animals to man's needs. Just as he collected statistics on human populations to assist in his economic evaluation of a region, so also he collected, when he could, statistics on farm products. If these products were coffee, indigo, or cotton, their quantities were expressed in weight, bulk, or monetary value, according to the demands of the market. But with hoofed animals it was usually easiest to merely count them, and in this case Humboldt could easily bring into play his knowledge of human demography. For example, when figures on animal populations were incomplete, he could apply the same methodology he used to estimate human populations from incomplete data: . . . In the Llanos of Caraccas the proprietors of the great hatos are entirely ignorant of the number of the cattle 57. PN, V, 110-1l1. 58. JR, pp. 446-447, 520-522. Darwin cited Humboldt, New Spain, IV, 199. 59. Karl Eduard Rothschuh, "Alexander von Humboldt und die Physiologie seiner Zeit," Sudhoifs Archiv, 43 (1959), 97-113.

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they possess. They only know that of the young cattle, which are branded every year with a letter or mark peculiar to each herd. The richest proprietors mark as many as 14,000 head every year; and sell to the number of five or six thousand. According to official documents,60 the exportation of hides from the whole Capitania General amounted annually for the West India islands alone to 174,000 skins of oxen and 11,500 of goats. When we reflect that these documents are taken from the books of the customhouses, where no mention is made of the fraudulent dealings in hides, we are tempted to believe that the estimation of 1,200,000 oxen wandering in the Llanos from the Rio Carony and the Guarapiche to the lake of Maracaybo is much underrated. The port of Guayra alone exported annually from 1789 to 1792, 70,000 or 80,000 hides entered in the customhouse books, scarcely one fifth of which was for Spain.61 And he compared the livestock populations of America and Europe, just as elsewhere he compared the human populations. At the same time he pointed out that civilization had progressed further in Europe, where more land was devoted to plant crops than to herds.02 Since the livestock populations were largely controlled by man, Humboldt sometimes indicated where more cattle or other domestic animals could easily be raised.63 Just as man himself was not entirely independent of his natural environment, neither were his animals. Sheep could not be raised in large numbers on the Venezuelan plains because the climate was too hot and they were too easily killed by jaguars and wolves.64

The domestic animals that flourished in Latin America had to be able to withstand many hardships: Harassed during the day by gadflies, and moschettoes, the horses, mules, and cows find themselves attacked at night by enormous bats, that fasten on their backs, and cause wounds that become dangerous, because they are [subsequently] filled with acaridae and other hurtful insects. In the time of great drought, the mules gnaw even the thorny melo60. Informe del Conde de Casa-Valencia, manuscript, which we have already quoted several times.-Humboldt's note. 61. PN, IV, 338-339. 62. PN, IV, 342. On comparison of European and American populations, see PN, VI, 335-342. New Spain, I, chap. 4, pp. 105-108. 63. PN, V, 573, 685. 64. PN, VI, 45.

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Humboldt, Darwin, and Population cactus . . . During the great inundations these same animals lead an amphibious life, surrounded by crocodiles, waterserpents, and manatees. Yet, such are the immutable laws of nature, their races are preserved in the struggle with the elements, and amid so many sufferings and dangers.65 But even when domestic animals struggled against the hardships of semi-wild conditions, they remained under some protection from man. Theirs was a far less intensive struggle for existence than that found in the jungles of South America. Humboldt reluctantly acknowledged this in a nostalgic passage: You find yourself in a new world, in the midst of untamed and savage nature. Now it is the jaguar, the beautiful panther of America, that appears upon the shore; and now the hocco66 with its black plumage and its tufted head that moves slowly among the sausoes. Animals of the most different classes succeed each other [on the banks, as one travels down the river]. "It is just as it was in Paradise," said our pilot, an old Indian of the missions. Every thing indeed here recalls to mind that state of the primitive world, the innocence and felicity of which ancient and venerable traditions have transmitted to all nations: but in carefully observing the manners of animals between themselves, we see that they mutually avoid and fear each other. The golden age has ceased; and in this Paradise of the American forests, as well as every where else, sad and long experience has taught all beings that benignity is seldom found in alliance with strength.67 Two examples of struggle in nature which seem to have especially impressed Humboldt were of amphibious species-the flying fish, hunted by dolphins in the ocean and birds in the air;68 and the capybara (Hydrochoerus hydrochaeris), hunted by crocodiles in the rivers and jaguars on the banks. Concerning the second of these "unfortunate animals," he expressed surprise that, without defenses before "two powerful enemies, they can become so numerous; but they breed with the same 65. PN, IV, 395-396. 66. "Crax alector, the peacock pheasant; C. pauxi, the cashew bird."Humboldt's note. C. alector L. 1766 is now called Black Curassow; C. pauxi = Pauxi pauxi (L. 1766), now called Helmeted Curassow. 67. PN, IV, 421-422. 68. PN, II, 14-15.

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rapidity as the cobayas, or little guinea pigs, which come to us from Brazil." 69 Distressing though such situations may have seemed to Humboldt, they nevertheless showed him that under natural conditions some species can survive intensive predation. This lesson could be applied to other situations where man was predator. The progress of civilization, eighteenth-century intellectuals were fond of saying, went through three phases: hunting, herding and husbandry. As a total means of subsistence, the first phase seemed too primitive to Humboldt to be desirable as a permanent means of subsistence.70 He must have felt, however, that certain wild animal populations should be wisely managed as a profitable natural resource. Three examples he met with in South America and discussed in some detail were pearls, guacharos, and arrau turtles. None of these, it may be noted, required the sacrifice of grazing or arable land for their maintenance. Humboldt's discussion of pearl fisheries showed a good grasp of significant factors in animal demography, but he lacked enough information to draw conclusions on its prospects in South America. He pointed out that although Ceylon had 600 pearl divers, they were only allowed to dive for one month a year, whereas at Cubagua they dived all year long. When one considered that the pearl oyster, which lived nine or ten years, only began making a pearl in its fourth year, it was evident that the rate at which they had been dug was too rapid for their growth rate.7' Hence, they had disappeared from Latin America except in Panama and the mouth of the Rio de la Hacha. Even if the annual harvest were better regulated, it was not certain that they would return, because their former sites might no longer be suitable for their needs: . . .We are ignorant whether earthquakes have altered the nature of the bottom of the sea, or whether the changes of the submarine currents may have had an influence either 69. PN, IV, 426. 70. He felt, however, that the shift from hunting to herding or husbandry involved a certain amount of loss of vitality: "The Indian of the Missions is more secure of subsistence. Not being continually struggling against hostile forces, against the elements and against man, he leads a more monotonous life, less active, and less fitted to impart energy to the mind, than the savage or independent Indian. PN, III, 220. See also III, 15. 71. Species determination in oysters is presently under dispute. See P. Korringa, "Recent Advances in Oyster Biology," Quart. Rev. Biol., 27 (1952), 266-308, 339-365.

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Humboldt, Darwin, and Population on the temperature of the water or on the abundance of certain molluscae on which the aronde feeds.72 The over-exploitation of pearl oysters may have warned Humboldt of this danger elsewhere. He expressed concern over this possibility when he became acquainted with the slaughter of nestling guacharos. This odd bird was first described scientifically by Humboldt, who pointed out that it "is almost the only frugiverous nocturnal bird that is yet known."73 It nested in great numbers in the Cavern of the Guacharo, located in the Sierra del Guacharo. Although the nests were located fifty to sixty feet above their heads, the Indians managed to knock the young out of the nests with poles. Each summer they killed several thousand nestlings for the fat deposits on their peritoneum. This fat was melted over fires and converted into cooking oil for the missionaries. The missionaries assured him that the numbers of the guacharos had not diminished because of this hunting. Humboldt attributed its survival to the Indians' fear of going as far back into the cave as the birds did and also to the habit of some guacharos of nesting in smaller caves, too narrow to admit the body of a man.74 The guacharo's range is greater than Humboldt knew, it being found in the Guianas, Trinidad, Venezuela, Colombia, Ecuador, Peru, and Bolivia.75 The one bit of information that Humboldt might have been able to supply, but did not, was the number of nestlings per nest.76 Again, he lacked enough 72. PN, II, 277. This pessimism was well founded, because the Latin American pearls did not achieve commercial importance, though their inferior quality was a factor as wel as their lack of abundance: "Philip the Second's celebrated pearl, which weighed 250 carats, and was valued at 150,000 dollars, came from St. Margarita. Yet the pearls of the West are not to be compared with those of the East in shape, beauty, colour, or texture. I am not aware that any established fishery is now conducted at St. Margarita, or on the coast of Columbia, on an extensive scale, after the failure of the Columbia and Panama speculation in 1826." John R. Philpots, Oysters, and All about Them, 2 vols. (London, Leicester: Richardson, 1890), II, 940. 73. PN, III, 126. A Latin description is on p. 125. 74. PN, III, 124-130. 75. Rodolphe Meyer de Schauensee, assisted by Eugene Eisenmann, The Species of Birds of South America and Their Distribution (Narberth, Pa.: Livingston Publishing Co. for Academy of Natural Sciences of Philadelphia, 1966), p. 146. 76. Some demographic details are now available: the normal clutch is 2 to 4 eggs, with a median of 2.7; it breeds on Trinidad from December to September, with a complete nesting cycle lasting five months; some adults raise two broods a year; there is a 50% nesting success. David W. Snow, "The Natural History of the Oilbird, Steatornis caripensis, in Trinidad,

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information to estimate the continuation of this resource, which has considerably diminished since he wrote. If mosquitoes are excepted, the most spectacular concentrations of animals that Humboldt witnessed were of the Arrau turtle (Podocnemis expansa Schweigger 1812), which laid its eggs on the beaches of a few islands in the Orinoco River near its junction with the Apure, some 450 miles inland. These turtles laid when the river was lowest, from the end of January until March 20-25. The Indians were waiting, but unless they waited out of sight the arraus would not come from the water. Formerly the Indian tribes competed with each other for the eggs, many of which were broken during conflicts. However, the eggs were deposited uniformly enough on the beaches that the missionaries could measure off a portion of the beaches for each tribe. The turtles would begin arriving soon after sunset, but the number of animals that dig the beach during the night is so considerable that day surprises many of them before the laying of their eggs is terminated. They are then urged on by the double necessity of depositing their eggs and closing the holes they have dug, that they may not be perceived by the tigers [before returning to the water].77 The late arraus were in danger of being caught by the Indians or jaguars. Having so often estimated human populations, Humboldt decided to estimate also the number of eggs laid annually by the arrau: W. I. Part 1: General Behavior and Breeding Habits," Zoologica (New York), 46 (1961), 27-49 + 2pls. "Part 2: Population, Breeding Ecology and Food," Zoologica, 47 (1962), 199-221 + 4 pls. I am endebted for asistance in locating this paper to Dr. Mary H. Clench, Department of Birds, Carnegie Museum, Pittsburgh. 77. PN, IV, 485. For recent accounts, see the following. Raymond M. Gilmore, "Fauna and Ethnozoology of South America," Handbook of South American Indians, Julian Haynes Steward, ed. (Washington: Smithsonian Institution, Bureau of American Ethnology, Bulletin 143, 1950), VI, 345464; see pp. 400-405. James Jerome Parsons, The Green Turtle and Man (Gainesville: University of Florida Press, 1962), pp. 84, 89-93. Janis A. Roze, "Pilgrim of the River," Natural History, 73, no. 7 (August 1964), 35-41. P. E. Vanzolini, "Notes on the Nesting Behaviour of Podocnemis expansa in the Amazon Valley (Testudines, Pelomedusidae)," Pap6is Avulsos de Zoologia, 20 (1967), 191-215. I am endebted for assistance in locating these sources and those in notes 80 and 81 to Neil D. Richmond, Department of Reptiles and Amphibians, Carnegie Museum, Pittsburgh, and to George R. Zug, Division of Reptiles and Amphibians, Smithsonian Institution, Washington, D.C.

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Humboldt, Darwin, and Population Estimating at one hundred, or one hundred and sixteen, the number of eggs that one tortoise produces; and reckoning that one third of these is broken at the time of laying, particularly by the mad [i.e., late] tortoises; we may presume that, to obtain annually five thousand jars of [egg] oil, three hundred and thirty thousand arrau tortoises, the weight of which amounts to one hundred and sixty-five quintals, must come and lay thirty-three millions of eggs on the three shores appropriated to this harvest.78 But this figure was only a preliminary estimate. He goes on to say that "the results of these calculations are much below the truth." One might wonder why he did not give the correct figures in the first place. The answer, though not stated, is that people are more skeptical of large than small figures. It was traditional to state the largest minimum figure that one could safely defend, and then argue upward, according to whatever additional evidence could be brought in. Humboldt's next evidence seems, however, to violate this tradition: "Many tortoises lay only sixty or seventy eggs." The apparent inconsistency disappears, though, when one realizes that he is arguing not for a reduction in the number of eggs present, but for an increase in the number of females laying them. Even all the females that arrived did not lay, because "a great number of these animals are devoured by jaguars at the moment they get out of the water." Now, his above estimate had been based upon the number of eggs that were used for making the egg oil. He went on to point out that many other eggs were laid which never became part of the oil, and he finally concluded: "We must admit that the number of turtles which annually deposite their eggs on the banks of the Lower Oroonoko is near a million. This number is very considerable for so large an animal, weighing half a quintal, and of which the greater part is destroyed by men." Humboldt saw very few male Arraus and wondered why. He could only say that it was unlikely that they killed each other during the mating season the way male crocodiles did.79 The Indians also dug up the eggs of another turtle, El Terecay (Podocnemis dumeriliana Schweigger 1812), which did not 78. PN, IV, 489. Young females lay only 50 to 60 eggs; the average number per nest is 82 to 85, and the maximum record is 150, according to Roze, 'Pilgrim of the River." 79. PN, IV, 495.

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lay them in communal areas, thus making it difficult to estimate their numbers.80 The population biology of two other kinds of animals, crocodiles and mosquitoes, interested Humboldt because they were hinderances to man. The Orinoco Crocodile (Crocodylus intermedius Graves 1819) was a man-killer. Humboldt's colleague, Aime Bonpland, measured a male that was 22 feet three inches long, which is the longest specimen ever recorded.81 Humboldt attempted to estimate its age, ostensibly from data on the Nile Crocodile (C. niloticus), which he reported reached puberty when ten years old and eight feet long. His calculations were not given, but since he concluded that it would reach 22 feet, three inches when 28 years old, he must have divided the total length by the rate of growth of the first 10 years, which was eight-tenths of one foot per year. These calculations actually appear to be based upon measurements made by Descourtilz at Santo Domingo on the North American Crocodile (C. acutus Cuvier 1807) 82 The Orinoco Crocodile seemed to feed primarily upon the capybara, which lived in groups of 50-60 on the river banks. The male crocodiles were rare, which Humboldt attributed to the weaker ones being killed by the stronger during the mating season.83 The female laid fewer eggs than did the arrau, which seemed connected with the fact that the female crocodile could easily defend herself and therefore return to her nest hole and help her young into the water when hatched, whereas the female arrau was too vulnerable to safely do this.84 Adult crocodiles were extremely difficult to kill, because there 80. Both P. expansa and P. dumeriliana are found in the Amazon as well as in the Orinoco. On their ranges see Fred Medem, "Informe sobre reptiles Colombianos (II.) El Conocimiento actual sobre la Distribucion geografica de las Testidinata en Colombia," Boletin del Museo de Ciencias Naturales (Caracas), 2-3 (1956-57, pub. 1958), 13-45; see pp. 25-26, 29. Medem, "Datos zoo-geograficos y ecologicos sobre los Crocodylia y Testudinata de los Rios Amazonas," Caldasia, 8 (1960), 341-351; see pp. 346, 348. 81. According to Fred Medem, "Informe sobre Reptiles Colombianos. III: Investigaciones sobre la Anatomia craneal; Distribucion geografica y ecologia de Crocodylus intermedius (Graves) en Colombia," Caldasia, 8 (1958), 175-215; see p. 212. 82. Michel ttienne Descourtilz (1775-ca. 1835), Voyages d'un naturaliste, et ses observations faits sur les trois r6gnes de la nature, dans plusieurs ports de mer FranCais, en Espagne, au continent de l'Am6rique septentrionale, d Saint-Yago de Cuba, et e St.-Domingne, 3 vols. (Paris: Dufart, p6re, 1809), III, 6-108; see p. 102 and chart facing p. 50. 83. PN, IV, 422-423. Humboldt cited Descourtilz, but without a title. 84. PN, IV, 494-495.

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Humboldt, Darwin, and Population were few places a gun shot could pierce their skin. Some individuals lived near Indian villages for years and pulled into the river unwary persons who ventured too near. Humboldt was pessimistic over the prospect of ever ridding the Orinoco and its tributaries of this menace because of the difficulty of killing them.85 Spectacular though the crocodiles, jaguars, turtles, and guacharos were, the animals that may have impressed Humboldt most were the mosquitoes. His tentative speculations concerning their possible connection to disease has been quoted above. Since this was only a vague possibility to him, his interest in them was much more aroused by their constant harassment. He reported that "the multitude of these little animals may render vast regions almost uninhabitable."86 Seldom did Humboldt's emotional reaction to a situation seem to inhibit his scientific thinking about it. Detestable though the mosquitoes were, he described with the assistance of Pierre Andre Latreille what he thought were five new species, with their habitats, and three of their determinations are still valid.87 Although his travel plans rendered it impractical for him to spend much time studying the life histories of the many kinds of mosquitoes, he urged other naturalists to undertake this task.88 He contributed, nevertheless, a substantial body of information. The part of the mosquito's life most easily observed is its feeding on man. Those who traveled the Orinoco were bound to notice that there was a wide range of difference in the pain different species inflicted when they bit. This being so, it was easy to notice that different species were active at different times of day and also that different species lived in different regions of the river system. He was very impressed by the regularity of their diurnal cycle and wondered what caused it. 85. PN, V, 705. 86. PN, V, 87 87. PN, V, 97-98. These were: Culex cyanopennis [= Psorophora ciliata (Fabricius 1794)]; C. lineatus [=P. lineata]; C. ferrox 1= P. ferox]; C. chloropterus [= Sabethes chloropterus]; and C. maculatus [ nomina dubia]. For taxonomy, geographical range, and bibliography, cf. Alan Stone, Kenneth L. Knight, and Helle Starcke, A Synoptic Catalog of the Mosquitoes of the World (Diptera, Culicidae) (Washington: Entomological Society of America, 1959), pp. 92, 125-127, 283. On the medical importance of P. ciliata and P. ferox, cf. William R. Horsfall, Mosquitoes: Their Bionomics and Relation to Disease (New York: Ronald Press, 1955), pp. 386-390, 399-401. On S. chloropterus, cf. Pedro Galindo, "Bionomics of Sabethes chloropterus Humboldt, a Vector of Sylvan Yellow Fever in Middle America," Amer. J. Tropical Med. Hyg., 7 (1958), 429-440. 88. PN, V, 93.

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A new species was likely to be encountered when one reached the point where a new tributary entered the main river. Even in the tropics, however, mosquitoes were absent from dry, elevated lands remote from bodies of water. Black waters, he found, were the most likely to lack mosquitoes, and he guessed that it related to the chemical nature of the water. The reason may instead have been that these waters were deep and did not provide sufficient breeding place for mosquitoes. Humboldt knew, however, the general features of the mosquito life cycle -that it does require a suitable place to lay its eggs, and that after hatching it spends about two-thirds of its life as a larva in water. He despaired of ever being rid of mosquitoes, but he did point out that by replacing the dense forests with open crop land, more water would evaporate and there would be fewer places for mosquitoes to breed.89 As with the arfau and the crocodile, he encountered a preponderance of females, which, he thought, "explains the immense increase of the species, each female laying several hundred eggs." 90 He, and others, wondered why these insects, which in many places must seldom have an opportunity to attack man, nevertheless did so vehemently when the opportunity arose: This voracity, this appetite for blood, seems surprising in little insects that live on vegetable juices and in a country almost entirely uninhabited. "What would these animals eat if we did not pass this way?" say the Creoles, in going through countries where there are only crocodiles covered with a scaly skin, and hairy monkeys.9' The answer, we now know, is that the females need mammalian blood for their eggs to mature, and that when man is not there, they do feed on the monkeys and other mammals and birds. This was far from obvious, and we find Darwin asking the same question.92 Humboldt also tried to discover why the sting of the mosquito was so painful. This account is fascinating, because we naturally admire someone who endures pain to gain knowledge. For the reader in the twentieth century there is an additional dimension of interest arising from our knowledge that, while 89. 90. 91. 92.

PN, V, 88-117. PN, V, 98. PN,V,108. JR, p. 200.

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Humboldt, Darwin, and Population watching the mosquitoes suck his blood, he might have been receiving a mortal infection.93 Although many others before Humboldt had endangered their comfort and even their lives in order to advance scientific knowledge, it seems very likely that Humboldt's account inspired Darwin to make similar observations upon himself when he was in South America.94 In addition to his direct discussions of population biology, Humboldt also discussed related topics. His Essai sur la geographie des plantes was an important contribution, and he also discussed the distribution of species in his Personal Narrative.95 But even though he made useful correlations between the distribution of plants and climatic conditions, he did not relate the distribution of species to population pressure. And though he pointed out that the plants on discontinuous land masses might provide evidence of a former land bridge, he did not actually develop a detailed understanding of the relationship between changes in the elevation of lands and the distribution of species. He also indicated that one could use fossils to clarify the present distribution of species, but he did not use this approach himself.96 He was unable to see how population dynamics, stratigraphy, and paleontology could be interrelated to provide an understanding of the origin and distribution of species. This synthesis, which owed a debt to Humboldt, was the achievement of Augustin de Candolle, Lyell, and Darwin, as I indicated in my previous paper. Humboldt's blindness to the above interrelationships did not lessen during the years between the publication of his Essai and his Personal Narrative, but on the contrary, led him to despair of the mystery of species distribution ever being solved: Even when nature does not produce the same species in analogous climates, either in the plains of isothermal parallels, or on tablelands the temperature of which resembles 93. PN, V, 114-115. On pp. 93-94 Humboldt stated that the Zancudo is a long-legged gnat. The quotation above indicates that it may have been an Anopheles mosquito. 94. JR, p. 161. Although Darwin was also bitten by the Benchuga (Triatoma infestans), a large blood-sucking bug of the Pampas, his account makes it clear that in that case it was involuntary. His description of the blood sucking of the Benchuga was from observations on another volunteer -one of the officers of the Beagle (ibid., pp. 403-404). 95. PN, I, iii-iv, 263-275; II, 53-56; III, 490-502; V, 180. Humboldt's Essai is cited above, n. 3. 96. Essai, p. 19. PN, I, iv-v.

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that of places nearer the poles, we still remark a striking resemblance of appearance and physiognomy in the vegetation of the most distant countries. This phenomenon is one of the most curious in the history of organic forms. I say the history; for in vain would reason forbid man to form hypotheses on the origins of things; he is not the less tormented with these insoluble problems of the distribution of beings.97 Since Humboldt was in many respects a synthesizer, his failure at this point is of great interest. One can dismiss the question by remarking that no man can see everything, and certainly this will suffice for at least a partial answer. But this blindness does not seem to have been so much from ignorance as from not having fully emancipated himself from earlier teachings. Two earlier points of view seem to have blocked his vision. The first of these was that, though highly regarding Malthus' Essay on the Principle of Population, he did not accept Malthus' belief that population pressure, or increase, is a constant and significant aspect of the living world. The second was his ignorance of the science of stratigraphy. This seems at first surprising, but one must remember that Humboldt studied at the Bergakademie Freiburg under Abraham Gottlob Werner (1749-1817), where the emphasis was up mining and mineralogy,98 and where stratigraphy was especially weak. Furthermore, stratigraphy was just emerging as a science at the beginning of the nineteenth century, when Humboldt wrote.99 He later came to understand the usefulness of diagnostic fossils for correlating sedimentary strata, and he discussed the subject capably in a treatise on rock formations.100 97. PN, III, 490-491. Thus, he must have influenced Kirby, Spence, and Swainson in their conviction that the laws of biogeography are forever inscrutable. See Egerton, "Studies of Animal Populations from Lamarck to Darwin," p. 230. 98. William Coleman, "Abraham Gottlob Werner vu par Alexander von Humboldt, avec des notes de Georges Cuvier," Sudhoifs Archiv, 47 (1963), 465-478. Walter Schellhas, "Alexander von Humboldt und Freiberg in Sachsen," in Alexander von Humboldt 14.9.1769-6.5.1859: Gedenkschrift zur 100. Wiederkehr seines Todestages, ed. Hans Ertel (Berlin. Akademie Verlag, 1959), pp. 337-422. 99. See Darwin's remark indicative of this, quoted above, n. 8. Cf. also, Rhoda Rappaport, "Problems and Sources in the History of Geology, 17491810," Hist. Sci., 3 (1964), 60-77. 100. Humboldt, Essai geognostique sur le gisement des roches dans les deux hWmisphWres(Paris, 1823; German trans., Strassburg, 1823). Citation from English anon. trans. entitled A Geognostical Essay on the Superposi-

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Humboldt, Darwin, and Population Darwin Darwin's discussions of animal demography in his Journal of Researches did not merely, like those on human demography, follow in Humboldt's footsteps. Instead, one finds Darwin moving ahead. Darwin's discussions of human demography were included because he wanted to provide a well-rounded account; these discussions served little theoretical function for him. But Lyell had shown him what Humboldt had not seen-that animal demography could shed light on the distribution of species, both in time and space. Animal demography was of interest to Darwin not primarily for its economic importance, though he sometimes noted this,'0' but as part of his groping for a better understanding of the distribution, extinction, and changes of species. He worked within a theoretical framework that Lyell established in his Principles of Geology, which brought to bear a wide range of stratigraphic, paleontological, and biological evidences upon the species question. Darwin's full awareness and appreciation of what Lyell had accomplished in this respect is evident in a footnote in which he referred to "the admirable laws first laid down by Mr. Lyell of the geographical distribution of animals as influenced by geological changes." 102 This statement was followed by the cautious and coy observation that "The whole reasoning, of course, is founded on the assumption of the immutability of species. Otherwise the changes might be considered as superinduced by different circumstances in the two regions during a length of time." 103 By the time he wrote his Journal of Researches, Darwin was already inclined toward a belief in evolution, but he knew that he was far from having all the answers he needed.104 Therefore, his observations in controtion of Rocks in Both Hemispheres (London: Longman, Hurst, Rees, Orme, Brown, and Green, 1823), pp. 30, 44-67. Most of this treatise was also published in 1822 under the title "Independance des Formations," in Dictionnaire des sciences naturelles (Strasbourg, Paris: F. G. Levrault, Le Normant), XXIII, 56-385. 101. JR, pp. 170, 524. 102. JR. p. 400. 103. JR, p. 400. 104. In his personal chronology, entitled "Joumal," he wrote under the year 1837: "In July opened first note book on 'Transmutation of Species' -Had been greatly struck from about Month of previous March on character of S. American fossils-& species on Galapagos Archipelago. These facts origin (especially latter) of all my views. From March 13th to end of September entirely employed in my Journal [of Researches]." "Darwin's Journal," ed. Gavin de Beer, Bull. British Mus.

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versial areas were often presented with minimal interpretation, but nevertheless in such a way that they bore upon the biological topics discussed by Lyell. The shift from Humboldt's to Lyell's frame of reference is immediately evident when Darwin discussed the introduction of domestic animals into South America. For Humboldt, this was part of the economic assessment of a region, but for Darwin it was part of the dynamics of the spread of species into new areas: According to the principles so well laid down by Mr. Lyell, few countries have undergone more remarkable changes, since the year 1535, when the first colonist of La Plata landed with seventy-two horses. The countless herds of horses, cattle, and sheep, not only have altered the whole aspect of the vegetation, but they have almost banished the guanaco, deer, and ostrich. Numberless other changes must likewise have taken place; the wild pig in some parts probably replaces the peccari; packs of wild dogs may be heard howling on the wooded banks of the less frequented streams; and the common cat, altered into a large and fierce animal, inhabits rocky hills. I have alluded to the invasion of the cardoon: in a like manner, the islands near the mouth of the Parana are thickly clothed with peach and orangetrees, springing from seeds canied there [from farms] by the waters of the river.105 This passage implies that introduced species often competed better than native ones which they replaced. Some of his other observations were also examples of competition. Concerning South American vultures, he observed: "If an animal dies on the plain the Gallinazo commences the feast, and then the two Caracaras pick the bones clean. These birds, although thus commonly feeding together, are far from being friends." 106 (Nat. Hist. ) Hist. Ser., 2 no. 1 (November 1959), 7. Camille Limoges has recently argued convincingly that Darwin became converted to evolution in late 1836. La selection naturelle. gtude sur la premiere constitution d'un concept (1837-1859) (Paris: Presses Universitaires de France, 1790), p. 19. 105. JR, pp. 138-139. Darwin made similar observations about the spread of introduced species in On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life (London: John Murray, 1859; citation from facsimile ed., Cambridge, Mass.: Harvard University Press, 1964), pp. 64-65. 106. JR, p. 64. The three vultures, with their present names given in square brackets, were: Gallinazo (Cathartes atratus) [= Black Vulture (Coragyps atratus (Bechstein 1793))]; Carrancha (Polyborus braziliensis)

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Humboldt, Darwin, and Population He also observed that related species have adjacent ranges but are not found on the same land.107 The interpretation of these examples now seems obvious, and one might expect that it was obvious to Darwin, particularly since Lyell had already provided a good argument for the importance of competition in nature. Nevertheless, I believe that at that time Darwin did not fully realize the implications of this idea and was not to do so until after he had read Malthus.108 The reason for his slowness was quite likely related to Humboldt's influence; Humboldt had not recognized the importance of competition, and yet he had described the South American scene so well. Another factor inhibiting Darwin's realization of the significance of competition was the common knowledge among naturalists that each species has a special station in nature, from which the conclusion was usually drawn that its station was secure against encroachment. Lyell had pointed out that the station of a species could be captured by an invader and the former occupant exterminated, but Darwin had not yet realized that this might be a common phenomenon in nature.109 In spite of his having dug interesting fossils in South America and having wondered what the world was like when those extinct species had lived, Humboldt did not offer in his Personal Narrative speculations on the causes of their extinction beyond the vague suggestion that the world had then been different.'10 Lyell had since made it clear how important extinction is for understanding the origin of species, and Darwin was alert for evidences. Having pointed out that the fossil species of an area are related to those presently living there,11' he next observed: "The greater number, if not all, of these extinct quadrupeds lived at a very recent period; and many of them were contemporaries of the existing molluscs." He [= Crested Caracara (P. plancus (Miller 1777))]; Chimango (Polyborus chimango) [= Milvago chimango (Vieillott 1816)]. 107. JR, pp. 143, 172, 195. 108. For a discussion of his reluctance to accept the importance of competition and his final conversion, see Egerton, "Studies of Animal Populations from Lamarck to Darwin," pp. 245-247. 109. Lyell, Principles of Geology, 1st ed., II, 142-156. See Darwin, JR, 520. 110. PN, IV, 556-557. See I, xxvii. 111. JR, pp. 209-210. This point was defended later in greater detail by Alfred Russel Wallace, "On the Law which has regulated the Introduction of New Species," Ann. Mag. Nat. Hist., ser. 2, 16 (1855), 184-196; facsimile ed. in Proc. Linnean Soc. London, 171 (1960), 141-153. On the history of the "law of the succession of types," see Limoges, La Selection naturelle, pp. 17-18.

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then remarked: "Since their loss, no very great physical changes can have taken place in the nature of the country." This being so, "What then has exterminated so many living creatures?" And, "Did those plains fail in pasture which afterwards were overrun by thousands and tens of thousands of the successors of the fresh stock introduced by the Spanish colonists?" He considered the causes of extermination accepted by Lyell, but without satisfaction: One is tempted to believe in such simple relations, as variation of climate and food, or introduction of enemies, or the increased numbers of other species, as the cause of the succession of races. But it may be asked whether it is probable that any such cause should have been in action during the same epoch over the whole northern hemisphere, so as to destroy the Elephas primigenus on the shores of Spain, on the plains of Siberia, and in Northern America; and in a like manner, the Bos urus over a range of scarcely less extent? Did such changes put a period to the life of Mastodon angustidens, and of the fossil horse, both in Europe and on the Cordillera in Southern America?"12 Although he gave no references at this point, Darwin felt more sympathetic to Brocchi's suggestion which Lyell had argued against, that a species, like its individual members, grows old and dies for physiological rather than environmental reasons: . . . it does not seem a necessary conclusion that the extinction of species, more than their creation, should exclusively depend on the nature (altered by physical changes) of their country. All that at present can be said with certainty is that, as with the individual, so with the species, the hour of life has run its course and is spent.1"3 The multiple extinctions which puzzled Darwin might conceivably be explained by a chain reaction set off by the extinction of an especially important species in an area. This possibility occurred to him when he contemplated the immense number of animals that were either directly or indirectly dependent upon kelp that grew off shore from Tierra del Fuego: 112. JR, p. 211. See also p. 354 on subsidence of land, and p. 525 on predation. 113. JR, p. 212. On Brocchi, see Egerton, "Studies of Animal Populations from Lamarck to Darwin," p. 235. Brocchi was not the last to defend this theory. See Henri Decugis, Le Vieillissement du monde vivant (Paris: Librairie Plon, Masson, 1941).

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Humboldt, Darwin, and Population I can only compare these great aquatic forests of the southern hemisphere with the terrestrial ones in the intertropical regions. Yet if the latter should be destroyed in any country, I do not believe nearly so many species of animals would perish as, under similar circumstances, would happen with the kelp. Amidst the leaves of this plant numerous species of fish live, which nowhere else would find food or shelter; with their destruction the many cormorants, divers, and other fishing birds, the otters, seals, and porpoises, would soon perish also; and lastly, the Fuegian savage, the miserable lord of this miserable land, would redouble his cannibal feast, decrease in numbers, and perhaps cease to exist.114 Darwin, like Humboldt, described a giant turtle that was eaten by man. But, unlike the Arrau, the Galapagos Tortoise (Geochelone elephantopus [Harlan] Fitzinger) is a terrestrial species found on a few islands. Its females do not assemble into such spectacular aggregations to lay their eggs. Darwin discussed the mortality factors of this species, but there was less occasion than with Humboldt to discuss reproductive dynamics."15 Darwin also expressed little interest in its management as a food source, though this needed consideration."16 He was primarily interested in the variations of this species from one Galapagos Island to another. CONCLUSIONS I have attempted to clarify some of the pathways in the development of Darwin's thinking. The foregoing examples of influence by no means include all that can be found by comparing Darwin's writings with Humboldt's. However, the above examples seem adequate to show the nature and extent of this influence. It now seems clear that Humboldt not only, 114. JR, p. 305. 115. There is some congregation of the females during the egg-laying period; a female lays 7 to 20 eggs, with the average being 9 to 10. John D. Hendrickson, "The GalApagos Tortoises, Geochelone Fitzinger 1835 (Testudo Linnaeus 1758 in Part)," in The Galdpagos. Proceedings of the Symposia of the Galdpagos International Scientific Project, Robert I. Bowman, ed. (Berkeley and Los Angeles: University of California Press, 1966), pp. 252-257. 116. JR, pp. 462-466. It was used extensively for food and has been exterminated or reduced to rarity on most of the Galapagos Islands. See Charles Haskins Townsend, "The GalMpagos Tortoises in Their Relation to the Whaling Industry; a Study of Old Logbooks," Zoologica (New York), 4 (1925), 55-135.

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as had been previously known, inspired Darwin to make a voyage of exploration, but also provided him with his basic orientation concerning how and what to observe and how to write about it. An important part of what Darwin assimilated from Humboldt was an appreciation of population analysis as a tool for assessing the state of societies and of the benefits and hardships which these societies can expect to receive from the living world around them. Darwin exhibited in his Journal of Researches a casual interest in the economic and political conditions of the countries he visited, but these considerations were much less important to him than to Humboldt. Instead, Darwin, with the assistance of Lyell's Principles of Geology, shifted from Humboldt's largely economic framework to a biological one built around the species question. This shift led Darwin away from a consideration of how the population biology of animals was related to man's economy to focus instead upon how population biology fitted into the economy of nature. Humboldt's Personal Narrative served very well as a model for Darwin's Journal of Researches, thereby helping Darwin gain scientific eminence. The Journal of Researches, like virtually all of Humboldt's writings, was a contribution to scientific orthodoxy. But Darwin had, along the way, acquired an urge to do more than just add his building blocks to the orthodox scientific edifice. He decided to rearrange those blocks of knowledge into a different structure, and for that task neither Humboldt's Personal Narrative nor any other of his works could serve as a model. Humboldt had lacked the confidence which Darwin needed that biogeography and the origin of species could be understood. Humboldt had not explored very far the possible connections between biology and geology. Nor had he provided a general synthetic account of population biology. Had he done so, he might have been more explicit about the extent of his endorsement of Malthus. But even if he had, Humboldt's strong orientation toward cooperation would probably have inhibited his recognition of the importance of competition in nature. Lyell, who had also benefited from reading Humboldt, gave Darwin insights that were lacking in Humboldt's Personal Narrative. Lyell admirably demonstrated how stratigraphy, paleontology, biogeography, and population biology could be interrelated, and his reasons for doing so were essentially the same as Darwin's. Lyell's understanding of biogeography and ecology came from the writings of Augustin-Pyramus de Can358

Humboldt, Darwin, and Population dolle as much as from Humboldt's, and from the former Lyell derived an appreciation for the importance of competition and also a confidence that the mysteries of biogeography could be explained."17 Furthermore, Lyell's discussion of all these subjects and also of evolution in his Principles of Geology is a good synthetic argument that was the ideal model for Darwin's greatest book. Darwin, having become convinced that species change through time, was able to synthesize in his mind the contributions which he had derived from the writings of Humboldt and Lyell as they applied to the species question. When Darwin wrote his Journal of Researches there were two large gaps in his thinking about evolution that bothered him-the mechanism of evolution and the causes of extinction. It was only after reading Malthus in 1838 that he realized, as Lyell had more or less pointed out, how important was competition in nature. He now had the general outlines for his theory, and in the 1845 abridged edition of his Journal, now retitled The Voyage of the Beagle, he inserted a fuller discussion of competition in nature which showed his awareness of its importance as an ecological factor."18 EPILOGUE:ALFRED RUSSEL WALLACE The above discussion bears directly upon the development of Alfred Russel Wallace's evolutionary concepts. Most likely he derived his appreciation for ecology and population biology from Humboldt, his appreciation of competition in nature from Malthus and Lyell, and his appreciation of the importance of stratigraphy and paleontology from Lyell, just as Darwin had. But, in addition, Wallace had the immense advantage of reading Darwin's Journal of Researches, which contained many hints about evolution, as indicated above."19 117. Egerton, "Studies of Animal Populations from Lamarck to Darwin," pp. 231-239. Idem, "The Biological Concept of Competition before Darwin," Actes du XII' Congres internat. Hist. Sci. (inpress). 118. Voyage of the Beagle (1845), pp. 174-176. 119. Wallace had read Humboldt, Malthus, Lyell, and Darwin before he wrote to Henry Walter Bates on 11 April 1846: "I was much pleased to find that you so well appreciated Lyell. I first read Darwin's "Journal" three or four years ago, and have lately re-read it. As the Journal of a scientific traveller, it is second only to Humboldt's 'Personal Narrative'-as a work of general interest, perhaps superior to it. . . . My reference to Darwin's 'Journal' and to Humboldt's 'Personal Narrative' indicate, I believe, the two works to whose inspiration I owe my determination to visit the tropics as a collector." Alfred Russel Wallace, My Life: A RecoTd of Events and

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Two scholars, McKinney and Beddall, have recently traced the development of Wallace's thoughts and have indicated that Darwin owed a larger debt to Wallace than has heretofore been acknowledged.'20 In my judgment they have not taken adequate account of the influence upon Wallace of Humboldlt's Personal Narrative and Darwin's Journal of Researches. Although both Darwin and Wallace read widely and were influenced by many naturalists, if one seeks to identify the major influences upon them, it is clear that Darwin stood on the shoulders of two giants-Humboldt and Lyell-and Wallace on the shoulders of three-Humboldt, Lyell, and Darwin. Acknowledgements I wish to thank my colleagues Professor Richard L. Schoenwald, History Department, and Mr. John V. Brindle, Hunt Botanical Library, Carnegie-Mellon University, for their most helpful advice concerning the style and organization of this paper. Opinions, 2 vols. (London: Chapman and Hall, 1905), I, 256. Elsewhere (I, 232) he indicated that he read Humboldt's Personal Narrative and Malthus' Essay on the Principle of Population while living in Leicester (which was from early 1844 until Easter, 1845). 120. H. Lewis McKinney, "Alfred Russel Wallace and the Discovery of Natural Selection," J. Hist. Med. Allied Sci., 21 (1966), 333-357. Barbara G. Beddall, "Wallace, Darwin, and the Theory of Natural Selection: A Study in the Development of Ideas and Attitudes," J. Hist. Biol., 1 (1968), 261-323.

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Baker, Jeffrey J., and Garland E. Allen. The Process of Biology: Primary Sources. Reading, Mass.: Addison-Wesley, 1970; 300 pp., illus.; $4.95 paperbound. A collection of readings geared for introductory biology courses, consisting of papers in experimental biology from the seventeenth century to 1968. The selections are well chosen to meet the editors' aim of helping students learn to read critically and analyze original research papers. The editors have added short introductions and footnotes to the papers. An excellent addition for the library of students and teachers of biology and its development. Bowers, John Z. Western Medical Pioneers in Feudal Japan. Baltimore: Johns Hopkins Press, 1970; xi + 245 pp.; $8.95. Dr. Bowers, president of the Josiah Macy, Jr. Foundation, has spent many years studying the development of Japanese medicine and medical education. His present book should appeal to a wide range of readers, for it explores the nature of Japanese culture and the rise of Western influences in Japan since the seventeenth century as reflected in medicine. Descartes, Rene. tYberden Menschen (1632) sowie Beschreibung des Menschlichen Korpers (1648). Nach ersten franzbsischen Ausgabe von 1664 ubersetzt und mit einter historischen Einleitung und Anmerkungen von Karl E. Rothschuh. Heidelberg: Verlag Lambert Schneider, 1969; 202 pp. Rothschuh's introductory essay on the role of physiology in Descartes' thought is a superb complement to his German translations and annotations of Descartes' two major biological works. Fearing, Franklin. Reflex Action. A Study in the History of Physiological Psychology. Cambridge, Mass.: MIT Press, 1970; xv + 350 pp.; $3.45 paperbound. Historians of biology and the behavioral sciences will welcome this reprint of Fearing's outstanding 1930 publication, which traces the attempts from Descartes to Sherrington to account for thought and action by the mechanics of reflex responses. Gasking, Elizabeth. The Rise of Experimental Biology. New

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York: Random House, 1970; viii + 178 pp., paperbound. "From the seventeenth to the nineteenth century," writes Dr. Gasking, "biologists struggled to establish an experimental science that would enable them to study all the vital functions." In this short but rich study, she examines the interplay between theory and the development of an experimental biology from Harvey to Claude Bemard. This volume, the second in the Random House Studies in the History of Science, is a good introduction for newcomers to this complex subject, and an excellent refresher for those familiar with the field. Handler, Philip, editor. Biology and the Future of Man. New York: Oxford University Press, 1970; xxiii + 936 pp., illus.; $12.50. The reports of 21 panels commissioned by the Committee on Science and Public Policy of the National Academy of Sciences. The panels were charged with the task of reviewing the current status of branches of the life sciences, delineating the major questions facing researchers in these fields, and assessing the significance of probable future advances for man's health and economy. The reports move from molecular studies in biology to ecological systems and industrial technology, concluding with a chapter on "biology and the future of man." Historical Studies in the Physical Sciences, vol. 1. Edited by Russell McCormmach. Philadelphia: University of Pennsylvania Press, 1969; ix + 314 pp.; $8.50. An annual journal in book format "devoted to the history of the physical sciences in the post-Scientific Revolution period." The journal will be particularly interested in an intellectual history approach to the physical sciences and in the study of the social functions of those sciences and the professional role of their practitioners. Koestler, Arthur, and J. R. Symthies. Beyond Reductionism. New Perspectives in the Life Sciences. London: Hutchinson and Co., 1969; x + 438 pp.; 70 S. The proceedings of a conference organized by Koestler in the summer of 1968, attended by 15 eminent scientists and scholars who share what Koestler calls a "holy discontent" with the still prevalent nineteenthcentury reductionist approach to the biological and behavioral sciences. In their papers and discussions, the participants seek common elements in their criticisms of the reductionist philosophy and grounds for the synthesis of a more "humanistically oriented" philosophy. McCulloch, Warren S. Embodiments of Mind. Cambridge, Mass.;

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The J. H. B. Bookshelf MIT Press, 1970; xx + 402 pp.; $2.95 paperbound. A collection of 21 essays by the late Warren McCulloch, whose work encompassed medicine, philosophy, mathematics, and cybernetics. The unifying theme of these papers, written over a 20-year span, is McCulloch's search for an experimental epistemology, an understanding of how the brain works in terms of its circuitry-"'an attempt to found a physiological theory of knowledge." Pantin, C.F.A. The Relations Between the Sciences. Edited with an introduction and notes by A. M. Pantin and W. H. Thorpe. London: Cambridge University Press, 1968; x + 206 pp.; $7.50. An expansion of the late Carl Pantin's Tarner Lectures at Trinity College. Pantin, by training a biologist specializing in invertebrate zoology, was knowledgeable in many areas of science, particularly physics and geology. His exploration of the relations between what he terms the "restricted" (physical) and "unrestricted" (biological) sciences and the goals of scientific investigations are of interest to the historian and philosopher of science as well as to the researcher in the physical or biological sciences. Rauschenberg, Roy Anthony. Daniel Carl Solander. Naturalist on the "Endeavour." Transactions of the American Philosophical Society, vol. 58 (November 1968); 66 pp. Solander, one of Linnaeus' outstanding students, was curator of the British Museum, served as naturalist for Cook's first voyage of discovery (1768-1771), and went on to become a prominent member of London's intellectual and social circles. Rauschenberg's monograph concisely traces Solander's career and assesses his place in eighteenth-century systematic biology. Rosenblueth, Arturo. Mind and Brain: A Philosophy of Science. Cambridge, Mass.: MIT Press, 1970; xii + 128 pp.; $5.95. Rosenblueth, a neurophsyiologist with a long-standing interest in the methodology and philosophy of scientific investigation, propounds a dualistic parallelism-mental events and the material world function on separate levels of reality that relate to each other but do not interact. He also argues persuasively for a more active role for the scientist in formulating philosophies of science. Schofield, Robert S. Mechanism and Materialism. British Natural Philosophy in an Age of Reason. Princeton, N.J.: Princeton University Press, 1969; vi + 336 pp.; $9.50. Professor Schofield examines science in eighteenth-century Britain through carefully tracing two dominant and opposing con-

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cepts of the nature of matter and its action: mechanism and materialism, both of which evolved from their advocates' interpretations of Newton's work. Schofield's rich study interrelates various areas of natural philosophy and explores the influences on them of Continental science, natural theology, and social and institutional changes. Siegel, Rudolph E. Galen on Sense Perception. Basel: S. Karger, 1970; xii + 216 pp., illus.; $15.35. A continuation of Siegel's exhaustive analysis of Galen's medical and physiological doctrines, based primarily on the Greek text of Galen's treatises. Half of the present work deals with problems of vision, and the second half with Galen's work on the perception of sound, odors, taste, touch, and pain. Each chapter also reviews the doctrines on sense perception of earlier Greek philosophers. Teas, Howard J., editor. Genetics and Developmental Biology. The Thomas Hunt Morgan Centennial Symposium. Lexington, Ky.: University of Kentucky Press, 1969; viii + 164 pp.; $6.50. Ten papers examine contemporary research in genetics and developmental biology stemming from foundations laid by the work of Morgan: molecular and cellular mechanisms of inheritance, the mechanism of gene action, the regulation of gene expression, and the mechanisms of development. A brief introduction provides a sketch of Morgan based on the recollection of his colleagues. Theorides, Jean. Un Grand M6decin et biologiste: Casimir-Joseph Davaine (1812-1882). Analecta Medico-Historica, vol. 4. New York: Pergamon Press, 1968; 238 pp. A study of Davaine's life and his career as a physician during the reign of Napoleon III, focusing on his researches into the microbial nature of infectious diseases. Wilson, Leonard C., editor. Sir Charles Lyell's Scientific Journals on the Species Question. New Haven, Conn.: Yale University Press, 1970; lxi + 572 pp.; $17.50. In 1961, studying Lyell's papers, Professor Wilson discovered the seven journals here reprinted, which record Lyell's thoughts on the problem of species and his correspondence with Darwin between 1855 and 1861. The journals, coupled with Wilson's lengthy analytical introduction and textual annotations, are a major addition to the literature on the development of evolutionary biology. Young, Robert M. Mind, Brain, and Adaptation in the Nineteenth Century. London: Oxford University Press, 1970; xiv + 278 pp.; $9.00. Professor Young's study of work on cerebral 364

The J. H. B. Bookshelf localization from Gall and Spurzheim to Ferrier is a major addition to the all too slim body of secondary sources in the history of the neurosciences. Young ably examines both the scientific-experimental and philosophical currents that united to form biologically based theories of cerebral functions, showing how various lines of inquiry, such as phrenology, sensory-motor physiology, associationist psychology, and evolutionary theory as applied to psychology, blended throughout the nineteenth century in the attempt to locate and explain action and sensation. Kruta, Vladislav. J. E. Purkyne (1787-1869) Physiologist. Prague: Academia, 1969; 137 pp.; illus.; price not included. The publication of this volume is one of several events, including an international symposium held in Prague in September 1969 and organized by Prof. Kruta, which marked the 100th anniversary of Purkyne's death. The subtitle describes the book as "A Short Account of His (Purkyne's) Contributions to the Progress of Physiology, with a Bibliography of His Works." Actually, the bibliography cites not only Purkyne's own writings (Part I, Collected Works; Part II, Chronological list of Purkyne's publications) but also, importantly, publications concerning Purkyne's life and work, with emphasis on his contributions to a broadly conceived physiology (pp. 114131). The references are grouped according to 18 topics, such as visual phenomena, human speech (phonetics), and physiological institutes. The bibliography is preceded by a chronology of the main events in Purkyne's life. In the text Kruta portrays, briefly, the status of physiology at the beginning of the 19th century and Purkyne's views on physiology, its importance for medicine, and its relation to pathology. At the heart of the chapter on physiological institutes is Kruta's translation of Purkyne's "Brief Report on the Origin and Present Conditions of the Physiological Institute at Breslau," written in 1841. The documentary as well as the esthetic value of the informative opusculum is enhanced by the inclusion of 31 photographs and drawings. LEHIGH UNIVERSITY

JOSEF

BROZEK

365

Index FALL 1970

"Action Propre and Action Commune. The Localization of Cerebral Function," Judith P. Swazey, 213-234 Adams, Mark B., "Towards a Synthesis: Population Concepts in Russian Evolutionary Thought, 1925-1935," 107-129 Adelmann, Howard B., Marcello Malpighi and the Evolution of Embryology, 155, 165-174 Aepinus, 248-249 Agassiz, Louis, relationship with F. W. Putnam, 131-135 Allen, Garland E., 361 Animal demography, 341-357; Darwin on, 353-357 Animal electricity, 248-250 Aristotle, Generation of Animals, 1-52

Bailyn, B., 183-184 Baker, Jeffrey J., and Garland E. Allen, The Process of Biology: Primary Sources, review, 361 Becarria, Giambatista, 245-246, 248-249 Bell, Charles, Idea of a New Anatomy of the Brain, 223-224 Berkeley, Edmund, "The History of the Naming of the Loblolly Bay," 149-154 Beyond Reductionism. New Perspectives in the Life Sciences, Arthur Koestler and J. R. Symthies, review, 362 Bichat, 218

Biology and the Future of Man, Philip Handler, review, 362 Blainville, Henri Ducrotay de, 145146 Blum, H., 207 Bonnet, Charles, 216, 230; on phyllotaxis, 300-305 Bowers, John Z., Western Medical Pioneers in Feudal Japan, review, 361 Braun, Alexander, 299-300, 306, 311-323 Broca, Paul, on phrenology, 230233 Browne, Thomas, 300, 301 Burkhardt, Richard W., Jr., "Lamarck, Evolution, and the Politics of Science," 275-298 Cabanis, P., 216, 217 Calandrini, Louis, 301-302 Caldani, Marc Antoine, 243-245 Cardiology, 253-274; Walter Gaskell on, 266-273 Cerebral function, 213-234 Chambers, Robert, Vestiges of the Natural History of Creation, review, 183 Chauvois, L., 54 Chetverikov, Sergei S., evolutionary thinking of, 107-129 Churchill, Frederick B., essay review of The History of Embryology as Intellectual History, 155181 Coleman, William, The Interpretation of Animal Form, 155, 178179

367

INDEX

Condillac, 216 Cooper, William, 139-141 Cope's law, 207-209 between Spencer Correspondence Foulerton Baird and Louis Agassiz, E. C. Herber, review, 184-185 Crombie, A. C., 54 Crombie, A. C., and M. A. Hoskin, History of Science, review, 185 Cu6not, L., on Dollo's Law, 202 Cutright, Paul R., Lewis and Clark: review, Naturalists, Pioneering 183 Cuvier, Georges, 137-139, 142, 144, 221, 291-296 Daniel Carl Solander. Naturalist on the "Endeavour." Transactions of the American Philosophical Society, Roy Anthony Rauschenberg, review, 363 "Darwin and the Physiologists, Or, the Medusa and Modern Cardiology," Richard D. French, 253274 Darwin, Charles, The Life and Letters of Charles Darwin, review, 183; The Origin of Species, 253255, 260; Insectivorous Plants, 325-360; 254; on population, Journal of Researches, 326-327, 330, 339, 353, 358-360; on animal demography, 353-357 Debus, Allen G., "Harvey and Fludd: The Irrational Factor in the Rational Science of the Seventeenth Century," 81-105 de Candolle, Auguste P., 303-305, 322 341-357; animal, Demography, Humboldt on, 341-352; Darwin on, 353-357 Demography, human, 332-341 De Motu Locale Animalium, William Harvey, 81 Deper6t, Charles: and Dollo's law, 202 Method: "Descartes' Physiological Position, Principles, Examples," Thomas S. Hall, 53-79 Descartes, Ren6, 214, 235; Description of the Human Body, 53, 64, 67; Treatise of Man, 53, 61, 62,

368

64; Discourse on Method, 61, 62; Treatise of Light, 62, 78-79; Uber den Menschen (1632) sowie BeMenschlichen des schreibung Korpers (1648), review, 361 Description of the Human Body, Descartes, 53, 64, 67 Determinism, Dollo's, 194 Dexter, Ralph W., "Historical Aspects of F. W. Putnam's Systematic Studies on Fishes," 131-135 Dew-Smith, A. B., 264-266 Discourse on Method, Descartes, 61, 62 Dollo, Louis: on evolution, 189-212; on paleontology, 193-201; determinism, 194; irreversibility, 195; "Laws of Evolution," appendix, 211-212 "Dollo on Dollo's Law: Irreversibility and the Status of Evolutionary Laws," Stephen Jay Gould, 189212 Dollo's law, 189-212; formulation of, 189-201; L. Cuenot on, 202; Charles Deperet on, 202 Dreyfus-Le Foyer, 54, 55 Dubinin, N.P., 107-129

Edinger, Tilly, 190-191, 204 Egerton, Frank N., "Humboldt, Darwin, and Population," 325-360 Electrical fluid, Haller's rejection of, 242-247 "Electricity and the Nervous Fluid," Roderick W. Home, 235-251 Electricity, animal, 248-250 Embodiments of Mind, Warren S. McCulloch, review, 362-363 Embryology, as intellectual history, 155-181 Essay on the Vital and other Involuntary Motions of Animals, Robert Whytt, 239-240 Essays in the History of Embryology and Biology, Jane M. Oppenheimer, 155, 177-178 Evolution: and population, 107-129; Chetverikov on, 107-129; Dollo on, 189-212 Lamarck's, ideas, Evolutionary Georges Cuvier on, 291-296

INDEX

Evolutionary laws and irreversibility, 207-210 Evolutionary theory, Lamarck's, 275-298 Fearing, Franklin, Reflex Action. A Study in the History of Physiological Psychology, review, 361 Fernel, 70-71 First Lines of Physiology, Hailer, 238, 243 Fishes, Putnam's studies on, 131135 Fleming, Donald, and B. Bailyn, The Intellectual Migration, review, 183-184 Flourens, Pierre, 215-217, 220, 222230 Fludd, Robert, 81-105; views on blood, 82-91; and Gassendi, 82, 91-96; and Harvey in Puritan era, 97-105 Fontana, Felice, 243 Foster, Michael, 254, 263-268 Franz, 234 French, Richard D., "Darwin and the Physiologists, Or, the Medusa and Modern Cardiology," 253-274 French, Roger K., Robert Whytt, The Soul and Medicine, review, 184 Fritsch, 232 From Molecule to Man, J. Z. Young and Tom Margerison, review, 187 Fullmer, June Z., Sir Humphrey Davy's Published Works, review, 184 Galen, 214; offspring, 70; on sense of smell, 75-77 Galen on Sense Perception, Rudolph E. Siegel, review, 364 Gall, Franz Joseph, on phrenology, 213-234 Galvani, 247, 250-251 Gaskell, Walter: and cardiological researches, 266-273 Gasking, Elizabeth, Investigations into Generation, 1651-1828, 155, 174-177; The Rise of Experimental Biology, review, 361-362 Gassendi, Pierre, 82, 91-96 Genetics, 107-129 Genetics anrd Developmental Biology, Howard J. Teas, review, 364

Georges-Berthier, A., 54-55 Gerstner, Patsy A., "Vertebrate Paleontology, an Early Nineteenth-Century Transatlantic Science," 137-148 Girard, A., 193 Godman, John D., 138-140 Goeth, J. W., 322-323 Goltz, Friedrich, 234 Gould, Stephen Jay, "Dollo on Dollo's Law; Irreversibility and the Status of Evolutionary Laws," 189-212 Grant, Robert E., 140 Hall. Thomas S., "Descartes' Physiological Method: Position, Principles, Examples," 53-79 Haller, Albrecht von, 235; on muscular contractions and nervous First Lines of fluid, 236-241; Physiology, 238, 243; rejection of electrical fluid, 242-247 Handler, Philip, Biology and the Future of Man, review, 362 Hardy-Weinberg law, 112 Harlan, Richard, 139-148 Harrison, Ross Granville, Organization and Development of the Embryo, review, 184 "Harvey and Fludd: The Irrational Factor in the Rational Science of the Seventeenth Century," Allen G. Debus, 81-105 Harvey, William, De Motu Locale Animalium, 81; and Fludd in Puritan era, 97-105 Heart, see Cardiology Hebb, D. O., 234 Herber, E. C., Correspondence between Spencer Foulerton Baird and Louis Agassiz, review, 184185 "Historical Aspects of F. W. Putnam's Systematic Studies on Fishes," Ralph W. Dexter, 131135 Historical Studies in the Physical Sciences, Russell McCormmach, review, 362 History of Embryology as Intellectual History, The, essay review of, Frederick B. Churchill, 155-181

369

INDEX

History of Science, A. C. Crombie and M. A. Hoskin, review, 185 "History of the Naming of the Loblolly Bay, The," Edmund Berkeley, 149-154 Hitzig, 232 Home, Roderick W., "Electricity and the Nervous Fluid," 235-251 Hoskin, M. A. 185 Huxley, Julian, 108-109 Human demography, 332-341 "Humboldt, Darwin, and Population," Frank N. Egerton, 325-260 Humboldt: and animal demography, 341-352 Idea of a New Anatomy of the Brain, Charles Bell, 223-224 Induction and Intuition in Scientific Thought, Peter B. Medwar, review, 185 Insectivorous Plants, Charles Darwin, 254 Institute of Experimental Biology, 115-116, 120 Intellectual Migration, The, Donald Fleming and B. Bailyn, review, 183-184 Interpretation of Animal Form, The, William Coleman, 155, 178-179 Investigations into Generation, 1651-1828, Elizabeth Gasking, 155, 174-177 Irreversibility, 189-212; Dollo's use of, 195; Dollo's definitions of, 195-196; debate over, 201-207; status of evolutionary laws and, 207-210 Jellryfish, E. A. Schafer on, 266-267 J. E. Purkyne (1787-1869) Physiologist, Vladislav Kruta, review, 365 Journal of Researches, Charles Darwin, 326-327, 330, 339, 353, 358360 Koestler, Arthur, and J. R. Symthies, Beyond Reductionism. New Perspectives in the Life Sciences, review, 362 Kruta, Vladislav, J. E. Purkyne (1787-1869) Physiologist, review, 365

370

Laghi, M., 243-245 Lamarck, as naturalist philosopher, 284-287 "Lamarck, Evolution, and the Politics of Science," Richard W. Burkhardt, Jr., 275-298 Lashley, 234 Lavoisier, chemistry of, 282, 285 Laws: Hardy-Weinberg, 112; irreversibility, 191; Cope's, 207-209; Willston's, 207-209; evolutionary, 207-210; see also Dollo's law "Laws of Evolution," Louis Dollo, appendix, 211-212 LeBorgne, 231 LeGallois, J. J. C., 224 Les Sciences de la vie dans la pensee frangaise du XVIII, siecle, Jacques Roger, 155-165 Leven en Werk van Hugo de Vries, P.H.W.A. de Veer, review, 186 Lewis and Clark: Pioneering Naturalists, Paul R. Cutright, review, 183 Life and Letters of Charles Darwin, The, Charles Darwin, review, 183 Lopez Pifiero, J. M., Medicina Historia Sociedad, review, 185 Lorry, M., 224 Lyell, Charles, 325-326; Principles of Geology, 353, 358-359 Magendie, 232 Maier, Michael, 86 Malthus, Thomas Robert, on population, 332-334 Marcello Malpighi and the Evolution of Embryology, Howard B. Adelmann, 155, 165-174 Margerison, Tom, 187 Martius, Carl Friedrich Philipp von, 304-305 Marx, 202 McCormmach, Russell, Historical Studies in the Physical Sciences, review, 362 McCulloch, Warren S., Embodiments of Mind, review, 362-363 Mechanism and Materialism. British Natural Philosophy in an Age of Reason, Robert S. Schofield, review, 363-364 Medawar, Peter B., Induction and

INDEX

Intuition in Scientific Thought, review, 185 Medicina Historia Sociedad, J. M. Lopez Pifiero, review, 185 Medicine and Science in the 1860's, F. L. N. Poynter, review, 185-186 Mind and Brain: A Philosophy of Science, Arturo Rosenblueth, review, 363 Mind, Brain, and Adaptation in the Nineteenth Century, Robert M. Young, review, 364-365 M., 'The William Montgomery, Origins of the Spiral Theory of Phyllotaxis," 299-323 Munk, Hermann, 234 Murchison, Roderick, 138 Muscular contractions and nervous fluid, Haller's discussion of, 236241 Norton, H. T. J., 116-117 Offspring: Galen on, 70 Olby, Robert C., Origins of Mendelism, review, 185 Oppenheimer, Jane M., Essays in the History of Embryology and Biology, 155, 177-178 Organization and Development of the Embryo, Ross Granville Harrison, review, 184 Origins of Mendelism, Robert C. Olby, review, 185 Origin of Species, The, Charles Darwin, 253-255, 260 "Origins of the Spiral Theory of The," William M. Phyllotaxis, Montgomery, 299-323 Owen, Richard, 140-141, 146-148 Pagel, Walter: on Fludd and Harvey, 82-83, 87, 90-91 Paleontology: vertebrate, 137-148; Dollo on, 193-201 Palisot, 302-303 Pantin, C. F. A., The Relations Between the Sciences, review, 363 Paracelsus, 85 Gall on, 213-234; Phrenology: Spurzheim on, 213-234; Broca on, 230-233 Braun on, 299-323; Phyllotaxis,

299-300, 306, 311-323; Schimper on, 299-300, 303, 305-323; Bonnet on, 300-305 Plague Killers, The, Greer Williams, review, 186-187 Plate, L., and law of irreversibility, 191 107-129; concepts, Population: Humboldt, Darwin and, 325-360; Malthus' theory of, 332-334; see also Demography Poynter, F. L. N., Medicine and Science in the 1860's, review, 185186 Preus, Anthony, "Science and Philosophy in Aristotle's Generation of Animals," 1-52 Principles of Geology, Charles Lyell, 353, 358-359 Process of Biology: Primary Sources, The, Jeffrey J. Baker and Garland E. Allen, review, 361 Putnam, F. W., 131-135 Raspail, Frangois-Vincent, 276-277, 296 Rauschenberg, Roy Anthony, Daniel Carl Solander, Naturalist on the "Endeavour." Transactions of the American Philosophical Society, review, 363 Reflex Action. A Study in the History of Physiological Psychology, Franklin Fearing, review, 361 Relations Between the Sciences, The, C. F. A. Pantin, review, 363 Rise of Experimental Biology, The, Elizabeth Gasking, review, 361362 Robert Whytt, The Soul and Medicine, Roger K. French, review, 184 Roger, Jacques, Les Sciences de la vie dans la pensee frangaise du XVIII' si&cle, 155-165 Rolando, Luigi, 224-226 Romanes, George, 254-274 Romashov, D. D., effects of isolation and population size on evolution, 107-129 Arturo, Mind and Rosenblueth, Brain: A Philosophy of Science, review, 363

371

INDEX

Rosenkreuz, Christian, 85 Rothschuh, K. E., 54 Russian population concepts, 129

107-

Saint-Hilaire, Geoffroy, 293, 295, 322 Sanderson, John Burdon, 254, 261262 Scene of Change, Warren Weaver, review, 186 Schifer, E. A.: and jellyfish, 266267 Schiller, J., 253-254 Schimper, Carl, 299-300, 303, 305323 Schofield, Robert S., Mechanism and Materialism. British Natural Philosophy in an Age of Reason, review, 363-364 "Science and Philosophy in Aristotle's Generation of Animals," Anthony Preus, 1-52 Science News Yearbook, 1969/1970, Science Service, review, 186 Sherrington, Charles, 268 Siegel, Rudolph E., Galen on Sense Perception, review, 364 Simpson, G. G., 108-109 Singer, Charles, 81-82 Sir Charles Lyell's Scientific Journals on the Species Question, Leonard C. Wilson, review, 364 Sir Humphrey Davy's Published Works, June Z. Fullmer, review, 184 Spencer, Herbert, 259 Spiral theory of phyllotaxis, 299323 Spurzheim, G.: on phrenology, 213234 Stahl, G. E., 57-59 Swazey, Judith P., "Action Propre and Action Commune. The Localization of Cerebral Function," 213-234 Symthies, J. R., 362 Teas, Howard J., Genetics and Developmental Biology, review, 364 Theorides, Jean, Un Grand M6decin et biologiste: Casimir-Joseph Davaine (1812-1882), review, 364

372

Thompson, John V., Zoological Researches and Illustrations, 18281834, review, 186 "Toward a Synthesis: Population Concepts in Russian Evolutionary Thought, 1925-1935," Mark B. Adams, 107-129 Treatise of Light, Descartes, 62, 7879 Treatise of Man, Descartes, 53, 61, 62, 64 tYber den Menschen (1632) sowie Beschreibung des Menschlichen Korpers (1648), Ren6 Descartes, review, 361 Un Grand M6dicin et biologiste: Casimir-Joseph Davaine (18121882), Jean Th6orides, review, 364 Vauquelin, Nicolas-Louis, 277 Veer, P. H. W. A. de, Leven en Werk van Hugo de VTies, review, 186 Vestiges of the Natural History of Creation, Robert Chambers, review, 183 "Vertebrate Paleontology, and Early Nineteenth-Century Transatlantic Science," Patsy A. Gerstner, 137148 von Irwing, Karl Franz, 217 Wallace, Alfred Russel, 359-360 Ward, Seth: Webster-Ward Debate, 97-105 Weaver, Warren, Scene of Change, review, 186 Webster, John: Webster-Ward Debate, 97-105 Western Medical Pioneers in Feudal Japan, John Z. Bowers, review, 361 Whytt, Robert, 237; Essay on the Vital and other Involuntary Motions of Animals, 239-240 Wilcke, Johan Carl, 248 Williams, Greer, The Plague Killers, review, 186-187 Willston's law, 207-209 Wilson, Leonard C., Sir Charles Lyell's Scientific Journals on the Species Question, review, 364 Wolff, 217

INDEX

Young, J. Z., and From Molecule 187 Young, Robert M., Adaptation in

Tom Margerison, to Man, review, Mind, Brain, and the Nineteenth

Century, review, 364-365 Zoological Researches and Illustrations, 1828-1834, John V. Thompson, review, 186

373