George Louis Leclerc, Comte de Buffon, was born in 1707 at Montbard, Burgundy, in the same year as Linné. He died at Paris in 1788, at the age of eighty-one years. He inherited a large property from his father, who was a councillor of the parliament of Burgundy. He studied at Dijon, and travelled abroad. Buffon was rich, but, greatly to his credit, devoted all his life to the care of the Royal Garden and to writing his works, being a most prolific author. He was not an observer, not even a closet naturalist. “I have passed,” he is reported to have said, “fifty years at my desk.” Appointed in 1739, when he was thirty-two years old, Intendant of the Royal Garden, he divided his time between his retreat at Montbard and Paris, spending four months in Paris and the remainder of the year at Montbard, away from the distractions and dissipations of the capital. It is significant that he wrote his great Histoire naturelle at Montbard and not at Paris, where were the collections of natural history.

His forte was that of a brilliant writer and most industrious compiler, a popularizer of science. He was at times a bold thinker; but his prudence, not to say timidity, in presenting in his ironical way his thoughts on the origin of things, is annoying, for we do not always understand what Buffon did really believe about the mutability or the fixity of species, as too plain speaking in the days he wrote often led to persecution and personal hazard.[125]

His cosmological ideas were based on those of Burnet and Leibnitz. His geological notions were founded on the labors of Palissy, Steno, Woodward, and Whiston. He depended upon his friend Daubenton for anatomical facts, and on Gueneau de Montbéliard and the Abbé Bexon for his zoölogical data. As Flourens says, “Buffon was not exactly an observer: others observed and discovered for him. He discovered, himself, the observations of others; he sought for ideas, others sought facts for him.” How fulsome his eulogists were is seen in the case of Flourens, who capped the climax in exclaiming, “Buffon is Leibnitz with the eloquence of Plato;” and he adds, “He did not write for savants: he wrote for all mankind.” No one now reads Buffon, while the works of Réaumur, who preceded him, are nearly as valuable as ever, since they are packed with careful observations.

The experiments of Redi, of Swammerdam, and of Vallisneri, and the observations of Réaumur, had no effect on Buffon, who maintained that, of the different forms of genesis, “spontaneous generation” is not only the most frequent and the most general, but the most ancient—namely, the primitive and the most universal.[126]

Buffon by nature was unsystematic, and he possessed little of the spirit or aim of the true investigator. He left no technical papers or memoirs, or what we would call contributions to science. In his history of animals he began with the domestic breeds, and then described those of most general, popular interest, those most known. He knew, as Malesherbes claimed, little about the works even of Linné and other systematists, neither grasping their principles nor apparently caring to know their methods. His single positive addition to zoölogical science was generalizations on the geographical distribution of animals. He recognized that the animals of the tropical and southern portions of the old and new worlds were entirely unlike, while those of North America and northern Eurasia were in many cases the same.

We will first bring together, as Flourens and also Butler have done, his scattered fragmentary views, or rather suggestions, on the fixity of species, and then present his thoughts on the mutability of species. “The species” is then “an abstract and general term.”[127] “There only exist individuals and suites of individuals, that is to say, species.”[128] He also says that Nature “imprints on each species its unalterable characters;” that “each species has an equal right to creation;”[129] that species, even those nearest allied, “are separated by an interval over which nature cannot pass;”[130] and that “each species having been independently created, the first individuals have served as a model for their descendants.”[131]

Buffon, however, shows the true scientific spirit in speaking of final causes.

“The pig,” he says, “is not formed as an original, special, and perfect type; its type is compounded of that of many other animals. It has parts which are evidently useless, or which, at any rate, it cannot use.” ... “But we, ever on the lookout to refer all parts to a certain end—when we can see no apparent use for them, suppose them to have hidden uses, and imagine connections which are without foundation, and serve only to obscure our perception of Nature as she really is: we fail to see that we thus rob philosophy of her true character, which is to inquire into the ‘how’ of these things—into the manner in which Nature acts—and that we substitute for this true object a vain idea, seeking to divine the ‘why’—the ends which she has proposed in acting” (tome v., p. 104, 1755, ex Butler).

The volumes of the Histoire naturelle on animals, beginning with tome iv., appeared in the years 1753 to 1767, or over a period of fourteen years. Butler, in his Evolution, Old and New, effectually disposes of Isidore Geoffroy St. Hilaire’s statement that at the beginning of his work (tome iv., 1753) he affirms the fixity of species, while from 1761 to 1766 he declares for variability. But Butler asserts from his reading of the first edition that “from the very first chapter onward he leant strongly to mutability, even if he did not openly avow his belief in it.... The reader who turns to Buffon himself will find that the idea that Buffon took a less advanced position in his old age than he had taken in middle life is also without foundation”[132] (p. 104).

But he had more to say on the other side, that of the mutability of species, and it is these tentative views that his commentators have assumed to have been his real sentiments or belief, and for this reason place Buffon among the evolutionists, though he had little or no idea of evolution in the enlarged and thoroughgoing sense of Lamarck.

He states, however, that the presence of callosities on the legs of the camel and llama “are the unmistakable results of rubbing or friction; so also with the callosities of baboons and the pouched monkeys, and the double soles of man’s feet.”[133] In this point he anticipates Erasmus Darwin and Lamarck. As we shall see, however, his notions were much less firmly grounded than those of Erasmus Darwin, who was a close observer as well as a profound thinker.

“If we consider each species in the different climates which it inhabits we shall find perceptible varieties as regards size and form; they all derive an impress to a greater or less extent from the climate in which they live. These changes are only made slowly and imperceptibly. Nature’s great workman is time. He marches ever with an even pace and does nothing by leaps and bounds, but by degrees, gradations, and succession he does all things; and the changes which he works—at first imperceptible—become little by little perceptible, and show themselves eventually in results about which there can be no mistake. Nevertheless, animals in a free, wild state are perhaps less subject than any other living beings, man not excepted, to alterations, changes, and variations of all kinds. Being free to choose their own food and climate, they vary less than domestic animals vary.”[134]

The Buffonian factor of the direct influence of climate is not in general of so thoroughgoing a character as usually supposed by the commentators of Buffon. He generally applies it to the superficial changes, such as the increase or decrease in the amount of hair, or similar modifications not usually regarded as specific characters. The modifications due to the direct influence of climate may be effected, he says, within even a few generations.

Under the head of geographical distribution (in tome ix., 1761), in which subject Buffon made his most original contribution to exact biology, he claims to have been the first “even to have suspected” that not a single tropical species is common to both eastern and western continents, but that the animals common to both continents are those adapted to a temperate or cold climate. He even anticipates the subject of migration in past geological times by supposing that those forms travelled from the Old World either over some land still unknown, or “more probably” over territory which has long since been submerged.[135]

The mammoth “was certainly the greatest and strongest of all quadrupeds, but it has disappeared; and if so, how many smaller, feebler, and less remarkable species must have perished without leaving us any traces or even hints of their having existed? How many other species have changed their nature, that is to say, become perfected or degraded, through great changes in the distribution of land and ocean; through the cultivation or neglect of the country which they inhabit; through the long-continued effects of climatic changes, so that they are no longer the same animals that they once were. Yet of all living beings after man the quadrupeds are the ones whose nature is most fixed and form most constant; birds and fishes vary much more easily; insects still more again than these; and if we descend to plants, which certainly cannot be excluded from animated nature, we shall be surprised at the readiness with which species are seen to vary, and at the ease with which they change their forms and adopt new natures.”[136]

The following passages, debarring the error of deriving all the American from the Old World forms, and the mistake in supposing that the American forms grew smaller than their ancestors in the Old World, certainly smack of the principle of isolation and segregation, and this is Buffon’s most important contribution to the theory of descent.

“It is probable, then, that all the animals of the New World are derived from congeners in the Old, without any deviation from the ordinary course of nature. We may believe that, having become separated in the lapse of ages by vast oceans and countries which they could not traverse, they have gradually been affected by, and derived impressions from, a climate which has itself been modified so as to become a new one through the operations of those same causes which dissociated the individuals of the Old and the New World from one another; thus in the course of time they have grown smaller and changed their characters. This, however, should not prevent our classifying them as different species now, for the difference is no less real though it dates from the creation. Nature, I maintain, is in a state of continual flux and movement. It is enough for man if he can grasp her as she is in his own time, and throw but a glance or two upon the past and future, so as to try and perceive what she may have been in former times and what one day she may attain to.”[137]

Buffon thus suggests the principle of the struggle for existence to prevent overcrowding, resulting in the maintenance of the balance of nature:

“It may be said that the movement of Nature turns upon two immovable pivots—one, the illimitable fecundity which she has given to all species; the other, the innumerable difficulties which reduce the results of that fecundity, and leave throughout time nearly the same quantity of individuals in every species; ... destruction and sterility follow closely upon excessive fecundity, and, independently of the contagion which follows inevitably upon overcrowding, each species has its own special sources of death and destruction, which are of themselves sufficient to compensate for excess in any past generation.”[138]

He also adds, “The species the least perfect, the most delicate, the most unwieldy, the least active, the most unarmed, etc., have already disappeared or will disappear.”[139]

On one occasion, in writing on the dog, he anticipates Erasmus Darwin and Lamarck in ascribing to the direct cause of modification the inner feelings of the animal modified, change of condition being the indirect cause.[140] He, however, did not suggest the idea of the transmission of acquired characters by heredity, and does not mention the word heredity.

These are all the facts he stated; but though not an observer, Buffon was a broad thinker, and was led from these few data to generalize, as he could well do, from the breadth of his knowledge of geology gained from the works of his predecessors, from Leibnitz to Woodward and Whiston.

“After the rapid glance,” he says, “at these variations, which indicate to us the special changes undergone by each species, there arises a more important consideration, and the view of which is broader; it is that of the transformation (changement) of the species themselves; it is that more ancient modification which has gone on from time immemorial, which seems to have been made in each family or, if we prefer, in each of the genera in which were comprised more or less allied species.”[141]

In the beginning of his first volume he states “that we can descend by almost imperceptible degrees from the most perfect creature to the most formless matter—from the most highly organized animal to the most entirely inorganic substance. We will recognize this gradation as the great work of nature; and we will observe it not only as regards size and form, but also in respect of movements and in the successive generations of every species.”

“Hence,” he continues, “arises the difficulty of arriving at any perfect system or method in dealing either with nature as a whole or even with any single one of her subdivisions. The gradations are so subtle that we are often obliged to make arbitrary divisions. Nature knows nothing about our classifications, and does not choose to lend herself to them without reasons. We therefore see a number of intermediate species and objects which it is very hard to classify, and which of necessity derange our system, whatever it may be.”[142]

This is all true, and was probably felt by Buffon’s predecessors, but it does not imply that he thought these forms had descended from one another.

“In thus comparing,” he adds, “all the animals, and placing them each in its proper genus, we shall find that the two hundred species whose history we have given may be reduced to a quite small number of families or principal sources from which it is not impossible that all the others may have issued.”[143]

He then establishes, on the one hand, nine species which he regarded as isolated, and, on the other, fifteen principal genera, primitive sources or, as we would say, ancestral forms, from which he derived all the animals (mammals) known to him.

Hence he believed that he could derive the dog, the jackal, the wolf, and the fox from a single one of these four species; yet he remarks, per contra, in 1753:

“Although we cannot demonstrate that the production of a species by modification is a thing impossible to nature, the number of contrary probabilities is so enormous that, even philosophically, we can scarcely doubt it; for if any species has been produced by the modification of another, if the species of ass has been derived from that of the horse, this could have been done only successively and by gradual steps: there would have been between the horse and ass a great number of intermediate animals, the first of which would gradually differ from the nature of the horse, and the last would gradually approach that of the ass; and why do we not see to-day the representatives, the descendants of those intermediate species? Why are only the two extremes living?” (tome iv., p. 390). “If we once admit that the ass belongs to the horse family, and that it only differs from it because it has been modified (dégénéré), we may likewise say that the monkey is of the same family as man, that it is a modified man, that man and the monkey have had a common origin like the horse and ass, that each family has had but a single source, and even that all the animals have come from a single animal, which in the succession of ages has produced, while perfecting and modifying itself, all the races of other animals” (tome iv., p. 382). “If it were known that in the animals there had been, I do not say several species, but a single one which had been produced by modification from another species; if it were true that the ass is only a modified horse, there would be no limit to the power of nature, and we would not be wrong in supposing that from a single being she has known how to derive, with time, all the other organized beings” (ibid., p. 382).

“But no. It is certain from revelation that all animals have alike been favored with the grace of an act of direct creation, and that the first pair of every species issued fully formed from the hands of the Creator” (tome iv., p. 383).

And yet we find him saying at the same period of his life, in the previous volume, that species “are the only beings in nature, beings perpetual, as ancient, as permanent as she.”[144] A few pages farther on in the same volume of the same work, apparently written at the same time, he is strongly and stoutly anti-evolutional, affirming: “The imprint of each species is a type whose principal features are graven in characters forever ineffaceable and permanent.”[145]

In this volume (iv., p. 55) he remarks that the senses, whether in man or in animals, may be greatly developed by exercise.

The impression left on the mind, after reading Buffon, is that even if he threw out these suggestions and then retracted them, from fear of annoyance or even persecution from the bigots of his time, he did not himself always take them seriously, but rather jotted them down as passing thoughts. Certainly he did not present them in the formal, forcible, and scientific way that Erasmus Darwin did. The result is that the tentative views of Buffon, which have to be with much research extracted from the forty-four volumes of his works, would now be regarded as in a degree superficial and valueless. But they appeared thirty-four years before Lamarck’s theory, and though not epoch-making, they are such as will render the name of Buffon memorable for all time.

Étienne Geoffroy St. Hilaire was born at Étampes, April 15, 1772. He died in Paris in 1844. He was destined for the church, but his tastes were for a scientific career. His acquaintance with the Abbé Haüy and Daubenton led him to study mineralogy. He was the means of liberating Haüy from a political prison; the Abbé, as the result of the events of August, 1792, being promptly set free at the request of the Academy of Sciences. The young Geoffroy was in his turn aided by the illustrious Haüy, who obtained for him the position of sub-guardian and demonstrator of mineralogy in the Cabinet of Natural History. At the early age of twenty-one years, as we have seen, he was elected professor of zoölogy in the museum, in charge of the department of mammals and birds. He was the means of securing for Cuvier, then of his own age, a position in the museum as professor-adjunct of comparative anatomy. For two years (1795 and 1796) the two youthful savants were inseparable, sharing the same apartments, the same table, the same amusements, the same studies, and their scientific papers were prepared in company and signed in common.

As early as 1795, before Lamarck had changed his views as to the stability of species, the young Geoffroy, then twenty-three years old, dared to claim that species may be only “les diverses dégénérations d’un même type.” These views he did not abandon, nor, on the other hand, did he actively promulgate them. It was not until thirty years later, in his memoir on the anatomy of the gavials, that he began the series of his works bearing on the question of species. In 1831 was held the famous debates between himself and Cuvier in the Academy of Sciences. But the contest was not so much on the causes of the variation of species as on the doctrine of homologies and the unity of organization in the animal kingdom.

It is modified, it changes, if the environment (milieu ambiant) varies, and according to the extent (selon la portée) of the variations of the latter.[146]

As the result, among recent or living beings there are no essential differences as regards them—“c’est le même cours d’événements,” or “la même marche d’excitation.”[147]

On the other hand, the monde ambiant having undergone more or less considerable change from one geological epoch to another, the atmosphere having even varied in its chemical composition, and the conditions of respiration having been thus modified,[148] the beings then living would differ in structure from their ancestors of ancient times, and would differ from them according “to the degree of the modifying power.”[149] Again, he says, “The animals living to-day have been derived by a series of uninterrupted generations from the extinct animals of the antediluvian world.”[150] He gave as an example the crocodiles of the present day, which he believed to have descended from the fossil forms. While he admitted the possibility of one type passing into another, separated by characters of more than generic value, he always, according to his son Isidore, rejected the view which made all the living species descend “d’une espèce antediluvienne primitive.”[151] It will be seen that Geoffroy St. Hilaire’s views were chiefly based on palæontological evidence. He was throughout broad and philosophical, and his eloquent demonstration in his Philosophie anatomique of the doctrine of homologies served to prepare the way for modern morphology, and affords one of the foundation stones on which rests the theory of descent. Though temporarily vanquished in the debate with Cuvier, who was a forceful debater and represented the views then prevalent, a later generation acknowledges that he was in the right, and remembers him as one of the founders of evolution.

CHAPTER XIV
THE VIEWS OF ERASMUS DARWIN

Erasmus Darwin, the grandfather of Charles Darwin, was born in 1731, or twenty-four years after Buffon. He was an English country physician with a large practice, and not only interested in philosophy, mechanics, and natural science, but given to didactic rhyming, as evinced by The Botanical Garden and The Loves of the Plants, the latter of which was translated into French in 1800, and into Italian in 1805. His “shrewd and homely mind,” his powers of keen observation and strong common sense were revealed in his celebrated work Zoonomia, which was published in two volumes in 1794, and translated into German in 1795–99. He was not a zoölogist, published no separate scientific articles, and his striking and original views on evolution, which were so far in advance of his time, appear mostly in the section on “Generation,” comprising 173 pages of his Zoonomia,[152] which was mainly a medical work. The book was widely read, excited much discussion, and his views decided opposition. Samuel Butler in his Evolution, Old and New (1879) remarks: “Paley’s Natural Theology is written throughout at the Zoonomia, though he is careful, moro suo, never to mention this work by name. Paley’s success was probably one of the chief causes of the neglect into which the Buffonian and Darwinian systems fell in this country.” Dr. Darwin died in the same year (1802) as that in which the Natural Theology was published.

Krause also writes of the reception given by his contemporaries to his “physio-philosophical ideas.” “They spoke of his wild and eccentric fancies, and the expression ‘Darwinising’ (as employed, for example, by the poet Coleridge when writing on Stillingfleet) was accepted in England nearly as the antithesis of sober biological investigation.”[153]

The grandson of Erasmus Darwin had little appreciation of the views of him of whom, through atavic heredity, he was the intellectual and scientific child. “It is curious,” he says in the ‘Historical Sketch’ of the Origin of Species—“it is curious how largely my grandfather, Dr. Erasmus Darwin, anticipated the views and erroneous grounds of opinion of Lamarck in his Zoonomia (vol. i., pp. 500–510), published in 1794.” It seems a little strange that Charles Darwin did not devote a few lines to stating just what his ancestor’s views were, for certain of them, as we shall see, are anticipations of his own.

The views of Erasmus Darwin may thus be summarily stated:

1. All animals have originated “from a single living filament” (p. 230), or, stated in other words, referring to the warm-blooded animals alone, “one is led to conclude that they have alike been produced from a similar living filament” (p. 236); and again he expresses the conjecture that one and the same kind of living filament is and has been the cause of all organic life (p. 244). It does not follow that he was a “spermist,” since he strongly argued against the incasement or “evolution” theory of Bonnet.

4. Contests of the males for the possession of the females, or law of battle. Under the head of desire he dwells on the desire of the male for the exclusive possession of the female; and “these have acquired weapons to combat each other for this purpose,” as the very thick, shield-like horny skin on the shoulders of the boar, and his tusks, the horns of the stag, the spurs of cocks and quails. “The final cause,” he says, “of this contest among the males seems to be that the strongest and most active animal should propagate the species, which should thence become improved” (p. 238). This savors so strongly of sexual selection that we wonder very much that Charles Darwin repudiated it as “erroneous.” It is not mentioned by Lamarck, nor is Dr. Darwin’s statement of the exertions and desires of animals at all similar to Lamarck’s, who could not have borrowed his ideas on appetency from Darwin or any other predecessor.

“Thirdly, when we enumerate the great changes produced in the species of animals before their maturity, as, for example, when the offspring reproduces the effects produced upon the parent by accident or cultivation; or the changes produced by the mixture of species, as in mules; or the changes produced probably by the exuberance of nourishment supplied to the fetus, as in monstrous births with additional limbs, many of these enormities of shape are propagated and continued as a variety, at least, if not as a new species of animal. I have seen a breed of cats with an additional claw on every foot; of poultry also with an additional claw, and with wings to their feet, and of others without rumps. Mr. Buffon mentions a breed of dogs without tails, which are common at Rome and Naples, which he supposes to have been produced by a custom, long established, of cutting their tails close off. There are many kinds of pigeons admired for their peculiarities which are more or less thus produced and propagated.”[154]

6. The means of procuring food has, he says, “diversified the forms of all species of animals. Thus the nose of the swine has become hard for the purpose of turning up the soil in search of insects and of roots. The trunk of the elephant is an elongation of the nose for the purpose of pulling down the branches of trees for his food, and for taking up water without bending his knees. Beasts of prey have acquired strong jaws or talons. Cattle have acquired a rough tongue and a rough palate to pull off the blades of grass, as cows and sheep. Some birds have acquired harder beaks to crack nuts, as the parrot. Others have acquired beaks to break the harder seeds, as sparrows. Others for the softer kinds of flowers, or the buds of trees, as the finches. Other birds have acquired long beaks to penetrate the moister soils in search of insects or roots, as woodcocks, and others broad ones to filtrate the water of lakes and to retain aquatic insects. All which seem to have been gradually produced during many generations by the perpetual endeavors of the creature to supply the want of food, and to have been delivered to their posterity with constant improvement of them for the purpose required” (p. 238).

7. The third great want among animals is that of security, which seems to have diversified the forms of their bodies and the color of them; these consist in the means of escaping other animals more powerful than themselves.[155] Hence some animals have acquired wings instead of legs, as the smaller birds, for purposes of escape. Others, great length of fin or of membrane, as the flying-fish and the bat. Others have acquired hard or armed shells, as the tortoise and the Echinus marinus (p. 239).

“The colors of insects,” he says, “and many smaller animals contribute to conceal them from the dangers which prey upon them. Caterpillars which feed on leaves are generally green; earthworms the color of the earth which they inhabit; butterflies, which frequent flowers, are colored like them; small birds which frequent hedges have greenish backs like the leaves, and light-colored bellies like the sky, and are hence less visible to the hawk, who passes under them or over them. Those birds which are much amongst flowers, as the goldfinch (Fringilla carduelis), are furnished with vivid colors. The lark, partridge, hare, are the color of dry vegetables or earth on which they rest. And frogs vary their color with the mud of the streams which they frequent; and those which live on trees are green. Fish, which are generally suspended in water, and swallows, which are generally suspended in air, have their backs the color of the distant ground, and their bellies of the sky. In the colder climates many of these become white during the existence of the snows. Hence there is apparent design in the colors of animals, whilst those of vegetables seem consequent to the other properties of the materials which possess them” (The Loves of the Plants, p. 38, note).

“Many ingenious philosophers have found so great difficulty in conceiving the manner of the reproduction of animals that they have supposed all the numerous progeny to have existed in miniature in the animal originally created, and that these infinitely minute forms are only evolved or distended as the embryon increases in the womb. This idea, besides being unsupported by any analogy we are acquainted with, ascribes a greater tenuity to organized matter than we can readily admit” (p. 317); and in another place he claims that “we cannot but be convinced that the fetus or embryon is formed by apposition of new parts, and not by the distention of a primordial nest of germs included one within another like the cups of a conjurer” (p. 235).

9. To explain instinct he suggests that the young simply imitate the acts or example of their parents. He says that wild birds choose spring as their building time “from the acquired knowledge that the mild temperature of the air is more convenient for hatching their eggs;” and further on, referring to the fact that seed-eating animals generally produce their young in spring, he suggests that it is “part of the traditional knowledge which they learn from the example of their parents.”[156]

10. Hybridity. He refers in a cursory way to the changes produced by the mixture of species, as in mules.

Of these ten factors or principles, and other views of Dr. Darwin, some are similar to those of Lamarck, while others are directly opposed. There are therefore no good grounds for supposing that Lamarck was indebted to Darwin for his views. Thus Erasmus Darwin supposes that the formation of organs precedes their use. As he says, “The lungs must be previously formed before their exertions to obtain fresh air can exist; the throat or œsophagus must be formed previous to the sensation or appetites of hunger and thirst” (Zoonomia, p. 222). Again (Zoonomia, i., p. 498), “From hence I conclude that with the acquisition of new parts, new sensations and new desires, as well as new powers, are produced” (p. 226). Lamarck does not carry his doctrine of use-inheritance so far as Erasmus Darwin, who claimed, what some still maintain at the present day, that the offspring reproduces “the effects produced upon the parent by accident or cultivation.”

Finally the principle of law of battle, or the combat between the males for the possession of the females, with the result “that the strongest and most active animal should propagate the species,” is not hinted at by Lamarck. This view, on the contrary, is one of the fundamental principles of the doctrine of natural selection, and was made use of by Charles Darwin and others. So also Erasmus anticipated Charles Darwin in the third great want of “security,” in seeking which the forms and colors of animals have been modified. This is an anticipation of the principle of protective mimicry, so much discussed in these days by Darwin, Wallace, and others, and which was not even mentioned by Lamarck. From the internal evidence of Lamarck’s writings we therefore infer that he was in no way indebted to Erasmus Darwin for any hints or ideas.[157]