FOOTNOTES:

FOOTNOTES:[186]'Hist. Nat. Gén.,' tom. ii. p. 404, 1859.[187]'Système des Animaux sans Vertèbres,' Paris, in-8, an. ix. (1801); 'Discours d'Ouverture,' p. 12, &c.; 'Recherches sur l'Organisation des Corps Vivants,' Paris, in-8, 1802, p. 50, &c.; 'Discours d'Ouverture d'un Cours de Zoologie pour l'an ix.,' Paris, in-8, 1803. This discourse is entirely devoted to the consideration of the question, "What is Species?"[188]'Discours d'Ouverture d'un Cours de Zoologie,' 1806, Paris, in-8, p. 8, &c.[189]See followingchapter.[190]'Hist, des Anim. sans Vertèb.,' tom, i., Introduction, 1reed., 1815; 'Syst. des Conn. Positives,' Paris, in-8, 1820, 1repart, 2mesect. ch. ii. p. 114, &c.[191]'Hist. Nat. Gén.,' tom. ii. p. 407.[192]'History of Creation,' English translation, vol. i. pp. 111, 112.[193]M. Martins' edition of the 'Philosophie Zoologique,' Paris, 1873. Introd., p. vi.[194]'Origin of Species,' p. 3, 1859.[195]'Vestiges of Creation,' ed. 1860, Proofs, Illustrations, &c., p. lxiv.[196]'Origin of Species,' ed. 1, p. 239; ed. 6, p. 231.[197]'Origin of Species,' ed. 1, p. 242; ed. 6, 1876, p. 233.[198]'Origin of Species,' p. 421, ed. 1876.[199]'Phil. Zool.,' vol. i. p. 404.[200]Ibid. vol. ii. p. 324.[201]'Phil. Zool.,' vol. ii. p. 410.[202]'Les Amours des Plantes,' Discours Prélim., p. 7. Paris, 1800.[203]Ibid., Notes du chant i., p. 202.[204]Ibid. p. 238.[205]'Zoonomia,' vol. i. p. 507.[206]'Les Amours des Plantes,' p. 360.[207]Vol. i. p. 231, ed. M. Martins, 1873.

[186]'Hist. Nat. Gén.,' tom. ii. p. 404, 1859.

[187]'Système des Animaux sans Vertèbres,' Paris, in-8, an. ix. (1801); 'Discours d'Ouverture,' p. 12, &c.; 'Recherches sur l'Organisation des Corps Vivants,' Paris, in-8, 1802, p. 50, &c.; 'Discours d'Ouverture d'un Cours de Zoologie pour l'an ix.,' Paris, in-8, 1803. This discourse is entirely devoted to the consideration of the question, "What is Species?"

[188]'Discours d'Ouverture d'un Cours de Zoologie,' 1806, Paris, in-8, p. 8, &c.

[189]See followingchapter.

[190]'Hist, des Anim. sans Vertèb.,' tom, i., Introduction, 1reed., 1815; 'Syst. des Conn. Positives,' Paris, in-8, 1820, 1repart, 2mesect. ch. ii. p. 114, &c.

[191]'Hist. Nat. Gén.,' tom. ii. p. 407.

[192]'History of Creation,' English translation, vol. i. pp. 111, 112.

[193]M. Martins' edition of the 'Philosophie Zoologique,' Paris, 1873. Introd., p. vi.

[194]'Origin of Species,' p. 3, 1859.

[195]'Vestiges of Creation,' ed. 1860, Proofs, Illustrations, &c., p. lxiv.

[196]'Origin of Species,' ed. 1, p. 239; ed. 6, p. 231.

[197]'Origin of Species,' ed. 1, p. 242; ed. 6, 1876, p. 233.

[198]'Origin of Species,' p. 421, ed. 1876.

[199]'Phil. Zool.,' vol. i. p. 404.

[200]Ibid. vol. ii. p. 324.

[201]'Phil. Zool.,' vol. ii. p. 410.

[202]'Les Amours des Plantes,' Discours Prélim., p. 7. Paris, 1800.

[203]Ibid., Notes du chant i., p. 202.

[204]Ibid. p. 238.

[205]'Zoonomia,' vol. i. p. 507.

[206]'Les Amours des Plantes,' p. 360.

[207]Vol. i. p. 231, ed. M. Martins, 1873.

CHAPTER XVII.

SUMMARY OF THE 'PHILOSOPHIE ZOOLOGIQUE.'

The first part of the 'Philosophie Zoologique' is the one which deals with the doctrine of evolution or descent with modification. It is to this, therefore, that our attention will be confined. Yet only a comparatively small part of the three hundred and fifty pages which constitute Lamarck's first part are devoted to setting forth the reasons which led him to arrive at his conclusions—the greater part of the volume being occupied with the classification of animals, which we may again omit, as foreign to our purpose.

I shall condense whenever I can, but I do not think the reader will find that I have left out much that bears upon the argument. I shall also use inverted commas while translating with such freedom as to omit several lines together, where I can do so without suppressing anything essential to the elucidation of Lamarck's meaning. I shall, however, throughout refer the reader to the page of the original work from which I am translating.

"The common origin of bodily and mental phenomena," says Lamarck in his preliminary chapter, "has been obscured, because we have studied themchiefly in man, who, as the most highly developed of living beings, presents the problem in its most difficult and complicated aspect. If we had begun our study with that of the lowest organisms, and had proceeded from these to the more complex ones, we should have seen the progression which is observable in organization, and the successive acquisition of various special organs, with new faculties for every additional organ. We should thus have seen that sense of needs—originally hardly perceptible, but gradually increasing in intensity and variety—has led to the attempt to gratify them; that the actions thus induced, having become habitual and energetic, have occasioned the development of organs adapted for their performance; that the force which excites organic movements can in the case of the lowest animals exist outside them and yet animate them; that this force was subsequently introduced into the animals themselves, and fixed within them; and, lastly, that it gave rise to sensibility and, in the end, to intelligence."[208]The reader had better be on his guard here, and whenever Lamarck is speculating about the lowest forms of action and sensation. I have thought it well, however, to give enough of these speculations, as occasion arises, to show their tendency.

"Sensation is not the proximate cause of organic movements. It may be so with the higher animals, but it cannot be shown to be so with plants, nor even with all known animals. At the outset of life there was none of that sensation which could only arisewhere organic beings had already attained a considerable development. Nature has done all by slow gradations, both organs and faculties being the outcome of a progressive development.[209]

"The mere composition of an animal is but a small part of what deserves study in connection with the animal itself. The effects of its surroundings in causing new wants, the effects of its wants in giving rise to actions, those of its actions in developing habits and tendencies, the effects of use and disuse as affecting any organ, the means which nature takes to preserve and make perfect what has been already acquired—these are all matters of the highest importance.[210]

"In their bearing upon these questions the invertebrate animals are more important and interesting than the vertebrate, for they are more in number, and being more in number are more varied; their variations are more marked, and the steps by which they have advanced in complexity are more easily observed.[211]

"I propose, therefore, to divide this work into three parts, of which the first shall deal with the conventions necessary for the treatment of the subject, the importance of analogical structures, and the meaning which should be attached to the word species. I will point out on the one hand the evidence of a graduated descending scale, as existing between the highest and the lowest organisms; and, on the other, the effect of surroundings and habits on the organs of living beings, as the cause of their development or arrest of development. Lastly, I will treat of the natural order ofanimals, and show what should be their fittest classification and arrangement."[212]

It seems unnecessary to give Lamarck's intentions with regard to his second and third parts, as they do not here concern us; they deal with the origin of life and mind.

The first chapter of the work opens with the importance of bearing in mind the difference between the conventional and the natural, that is to say, between words and things. Here, as indeed largely throughout this part of his work, he follows Buffon, by whom he is evidently influenced.

"The conventional deals with systems of arrangement, classification, orders, families, genera, and the nomenclature, whether of different sections or of individual objects.

"An arrangement should be called systematic, or arbitrary, when it does not conform to the genealogical order taken by nature in the development of the things arranged, and when, by consequence it is not founded upon well-considered analogies. There is such a thing as a natural order in every department of nature; it is the order in which its several component items have been successively developed.[213]

"Some lines certainly seem to have been drawn by Nature herself. It was hard to believe that mammals, for example, and birds, were not well-defined classes. Nevertheless the sharpness of definition was an illusion, and due only to our limited knowledge. The ornithorhynchus and the echidna bridge the gulf.[214]

"Simplicity is the main end of any classification. If all the races, or as they are called, species, of any kingdom were perfectly known, and if the true analogies between each species, and between the groups which species form, were also known, so that their approximations to each other and the position of the several groups were in conformity with the natural analogies between them—then classes, orders, sections, and genera would be families, larger or smaller; for each division would be a greater or smaller section of a natural order or sequence.[215]But in this case it would be very difficult to assign the limits of each division; they would be continually subjected to arbitrary alteration, and agreement would only exist where plain and palpable gaps were manifest in our series. Happily, however, for classifiers there are, and will always probably remain, a number of unknown forms."[216]

That the foregoing is still felt to be true by those who accept evolution, may be seen from the following passage, taken from Mr. Darwin's 'Origin of Species':—

"As all the organic beings which have ever lived can be arranged within a few great classes; and as all within each class have, according to our theory, been connected together by fine gradations, the best, and if our collections were nearly perfect, the only possible arrangement would be genealogical: descent being the hidden bond of connection which naturalists have been seeking under the term of the Natural System. On this view, we can understand how it is that in the eyes of most naturalists, the structure of the embryo iseven more important for classifications than that of the adult."[217]

In his second chapter Lamarck deals with the importance of comparative anatomy, and the study of homologous structures. These indicate a sort of blood relationship between the individuals in which they are found, and are our safest guide to any natural system of classification. Their importance is not confined to the study of classes, families, or even species; they must be studied also in the individuals of each species, as it is thus only, that we can recognize either identity or difference of species. The results arrived at, however, are only trustworthy over a limited period, for though the individuals of any species commonly so resemble one another at any given time, as to enable us to generalize from them, at the date of our observing them, yet species are not fixed and immutable through all time: they change, though with such extreme slowness that we do not observe their doing so, and when we come upon a species thathaschanged, we consider it as a new one, and as having always been such as we now see it.[218]

"It is none the less true that when we compare the same kind of organs in different individuals, we can quickly and easily tell whether they are very like each other or not, and hence, whether the animals or plants in which they are found, should be set down as members of the same or of a different species. It is only therefore the general inference drawn from theapparent immutability of species, that has been too inconsiderately drawn.[219]

"The analogies and points of agreement between living organisms, are always incomplete when based upon the consideration of any single organ only. But though still incomplete, they will be much more important according as the organ on which they are founded is an essential one or otherwise.

"With animals, those analogies are most important which exist between organs most necessary for the conservation of their life. With plants, between their organs of generation. Hence, with animals, it will be the interior structure which will determine the most important analogies: with plants it will be the manner in which they fructify.[220]

"With animals we should look to nerves, organs of respiration, and those of the circulation; with plants, to the embryo and its accessories, the sexual organs of their flowers, &c.[221]To do this, will set us on to the Natural Method, which is as it were a sketch traced by man of the order taken by Nature in her productions.[222]Nevertheless the divisions which we shall be obliged to establish, will still be arbitrary and artificial, though presenting to our view sections arranged in the order which Nature has pursued.[223]

"What, then," he asks,[224]"isspecies—and can we show that species has changed—however slowly?" He now covers some of the ground since enlarged upon in Mr. Darwin's second chapter, in which the arbitrarynature of the distinction between species and varieties is so well exposed. "I shall show," says Lamarck (in substance, but I am compelled to condense much), "that the habits by which we now recognize any species, are due to the conditions of life [circonstances] under which it has for a long time existed, and that these habits have had such an influence upon the structure of each individual of the species, as to have at length modified this structure, and adapted it to the habits which have been contracted.[225]

"The individuals of any species," he continues, "certainly resemble their parents; it is a universal law of nature that all offspring should differ but little from its immediate progenitors, but this does not justify the ordinary belief that species never vary. Indeed, naturalists themselves are in continual difficulty as regards distinguishing species from varieties; they do not recognize the fact that species are only constant as long as the conditions in which they are placed are constant. Individuals vary and form breeds which blend so insensibly into the neighbouring species, that the distinctions made by naturalists between species and varieties, are for the most part arbitrary, and the confusion upon this head is becoming day by day more serious.[226]

"Not perceiving that species will not vary as long as the conditions in which they are placed remain essentially unchanged, naturalists have supposed that each species was due to a special act of creation on the part of the Supreme Author of all things. Assuredly, nothingcan exist but by the will of this Supreme Author, but can we venture to assign rules to him in the execution of his will? May not his infinite power have chosen to create an order of things which should evolve in succession all that we know as well as all that we do not know? Whether we regard species as created or evolved, the boundlessness of his power remains unchanged, and incapable of any diminution whatsoever. Let us then confine ourselves simply to observing the facts around us, and if we find any clue to the path taken by Nature, let us say fearlessly that it has pleased her Almighty Author that she should take this path.[227]

"What applies to species applies also to genera; the further our knowledge extends, the more difficult do we find it to assign its exact limits to any genus. Gaps in our collections are being continually filled up, to the effacement of our dividing lines of demarcation. We are thus compelled to settle the limits of species and variety arbitrarily, and in a manner about which there will be constant disagreement. Naturalists are daily classifying new species which blend into one another so insensibly that there can hardly be found words to express the minute differences between them. The gaps that exist are simply due to our not having yet found the connecting species.

"I do not, however, mean to say that animal life forms a simple and continuously blended series. Life is rather comparable to a ramification. In life we should see, as it were, a ramified continuity, if certain species had not been lost. The species which, accordingto this illustration, stands at the extremity of each bough, should bear a resemblance, at least upon one side, to the other neighbouring species; and this certainly is what we observe in nature.

"Having arranged living forms in such an order as this, let us take one, and then, passing over several boughs, let us take another at some distance from it; a wide difference will now be seen between the species which the forms selected represent. Our earliest collections supplied us with such distantly allied forms only; now, however, that we have such an infinitely greater number of specimens, we can see that many of them blend one into the other without presenting noteworthy differences at any step."[228]

This has been well extended by Mr. Darwin in a passage which begins:—"The affinities of all beings of the same class have sometimes been represented by a great tree. I believe that this simile largely speaks the truth."[229]

"What, then," continues Lamarck, "can be the cause of all this? Surely the following: namely, that when individuals of any species change their situation, climate, mode of existence, or habits [conditions of life], their structure, form, organization, and in fact their whole being becomes little by little modified, till in the course of time it responds to the changes experienced by the creature."[230]

In his preface Lamarck had already declared that "the thread which gives us a clue to the causes of thevarious phenomena of animal organization, in the manifold diversity of its developments, is to be found in the fact that Nature conserves in offspring all that their life and environments has developed in parents." Heredity—"the hidden bond of common descent"—tempered with the modifications induced by changed habits—which changed habits are due to new conditions and surroundings—this with Lamarck, as with Buffon and Dr. Darwin, is the explanation of the diversity of forms which we observe in nature. He now goes on to support this—briefly, in accordance with his design—but with sufficient detail to prevent all possibility of mistake about his meaning.

"In the same climate differences in situation, and a greater or less degree of exposure, affect simply, in the first instance, the individuals exposed to them; but in the course of time, these repeated differences of surroundings in individuals which reproduce themselves continually under similar circumstances, induce differences which become part of their very nature; so that after many successive generations, these individuals, which were originally, we will say, of any given species, become transformed into a different one."[231]

"Let us suppose that a grass growing in a low-lying meadow gets carried by some accident to the brow of a neighbouring hill, where the soil is still damp enough for the plant to be able to exist. Let it live here for many generations, till it has become thoroughly accustomed to its position, and let it then gradually find its way to the dry and almost arid soil of a mountain side;if the plant is able to stand the change and to perpetuate itself for many generations, it will have become so changed that botanists will class it as a new species."[232]

"The same sort of process goes on in the animal kingdom, but animals are modified more slowly than plants."[233]

The sterility of hybrids, to which Mr. Darwin devotes a great part of the ninth chapter of his 'Origin of Species,'[234]is then touched on—briefly, but sufficiently—as follows:—

"The idea that species were fixed and immutable involved the belief that distinct species could not be fertileinter se. But unfortunately observation has proved, and daily proves, that this supposition is unfounded. Hybrids are very common among plants, and quite sufficiently so among animals to show that the boundaries of these so-called immutable species are not so well defined as has been supposed. Often, indeed, there is no offspring between the individuals of what are called distinct species, especially when they are widely different, and again, the offspring when produced is generally sterile; but when there is less difference between the parents, both the difficulty of breeding the hybrid, and its sterility when produced, are found to disappear. In this very power of crossing we see a source from which breeds, and ultimately species, may arise."[235]

Mr. Darwin arrives at the same conclusion. He writes:—

"We must, therefore, either give up the belief of the universal sterility of species when crossed, or we must look at this sterility in animals, not as an indelible characteristic, but as one capable of being removed by domestication.

"Finally, on considering all the ascertained facts on the intercrossing of plants and animals, it may be concluded that some degree of sterility, both in first crosses and in hybrids, is an exceedingly general result, but that it cannot, under our present state of knowledge, be considered as absolutely universal."[236]

Returning to Lamarck, we find him saying:—

"The limits, therefore, of so-called species are not so constant and unvarying as is commonly supposed. Consider also the following. All living forms upon the face of the globe have been brought forth in the course of infinite time by the process of generation only. Nature has directly created none but the lowest organisms; these she is still producing every day, they being, as it were, the first sketches of life, and produced by what is called spontaneous generation. Organs have been gradually developed in these low forms, and these organs have in the course of time increased in diversity and complexity. The power of growth in each living body has given rise to various modes of reproduction, and thus progress, already acquired, has been preserved and handed down to offspring.[237]With sufficient time, favourable conditions of life [circonstances], successive changes in the surface of the globe, and the power of new surroundings and habits to modify the organs ofliving bodies, all animal and vegetable forms have been imperceptibly rendered such as we now see them. It follows that species will be constant only in relation to their environments, and cannot be as old as Nature herself.

"But what are we to say of instinct? Can we suppose that all the tricks, cunning, artifices, precautions, patience, and skill of animals are due to evolution only? Must we not see here the design of an all-powerful Creator? No one certainly will assign limits to the Creator's power, but it is a bold thing to say that he did not choose to work in this way or that way, when his own handiwork declares to us that this is the way he chose. I find proof in Nature—meaning by nature theensembleof all that is,[238]but regarding her as herself the effect of an unknown first cause[239]—that she is the author of organization, life, and even sensation; that she has multiplied and diversified the organs and mental powers of the creatures which she sustains and reproduces; that she has developed in animals, through the sole instrumentality of sense of need as establishing and directing their habits, all actions and all habits, from the simplest up to those which constitute instinct, industry, and finally reason.[240]

"Against this it is alleged that we have no reason to believe species to have changed within any known era. The skeletons of some Egyptian birds, preserved two or three thousand years ago, differ in no particular from the same kind of creatures at the present day. But this is what we should expect, inasmuch as the position andclimate of Egypt itself do not appear to have changed. If the conditions of life have not varied, why should the species subjected to those conditions have done so? Moreover, birds can move about freely, and if one place does not suit them they can find another that does. All that these Egyptian mummies really prove is, that there were animals in Egypt two or three thousand years ago which are like the animals of to-day; but how short a space is two or three thousand years, as compared with the time which Nature has had at her disposal! A time infinitely greatquâman, is still infinitely shortquâNature.[241]

"If, however, we turn to animals under confinement, we find immediate proof that the most startling changes are capable of being produced after some generations of changed habits. In the sixth chapter we shall have occasion to observe the power of changed conditions [circonstances] to develop new desires in animals, and to induce new courses of action; we shall see the power which these new actions will have, after a certain amount of repetition, to engender new habits and tendencies; and we shall also note the effects of use and disuse in either fortifying and developing an organ, or in diminishing it and causing it to disappear. With plants under domestication, we shall find corresponding phenomena. Species will thus appear to be unchangeable for comparatively short periods only."[242]

It is interesting to see that Mr. Darwin lays no less stress on the study of animals and plants under domestication than Buffon, Dr. Darwin, and Lamarck.Indeed, all four writers appear to have been in great measure led to their conclusions by this very study. "At the commencement of my investigations," writes Mr. Darwin, "it seemed to me probable that a careful study of domesticated animals and of cultivated plants would offer the best chance of making out this obscure problem. Nor have I been disappointed; in this and in all other perplexing cases, I have invariably found that our knowledge, imperfect though it be, of variation under domestication, afforded the best and safest clue. I may venture to express my conviction of the high value of such studies, though they have been very commonly neglected by naturalists."[243]

In justice to the three writers whom I have named, it should be borne in mind that they also ventured to express their conviction of the high value of these studies. Buffon, indeed, as we have seen, gives animals under domestication the foremost place in his work. He does not treat of wild animals till he has said all he has to say upon our most important domesticated breeds,—on whose descent from one or two wild stocks he is never weary of insisting. It was doubtless because of the opportunities they afforded him for demonstrating the plasticity of living organism that the most important position in his work was assigned to them.

Lamarck professes himself unable to make up his mind about extinct species; how far, that is to say, whole breeds must be considered as having died out, or how far the difference between so many now living andfossil forms is due to the fact that our living species are modified descendants of the fossil ones. Such large parts of the globe were still practically unknown in Lamarck's time, and the recent discovery of the ornithorhynchus has raised such hopes as to what might yet be found in Australia, that he was inclined to think that only such creatures as man found hurtful to him, as, for example, the megatherium and the mastodon, had become truly extinct, nor was he, it would seem, without a hope that these would yet one day be discovered. The climatic and geological changes that have occurred in past ages, would, he believed, account for all the difference which we observe between living and fossil forms, inasmuch as they would have changed the conditions under which animals lived, and therefore their habits and organs would have become correspondingly modified. He therefore rather wondered to find so much, than so little, resemblance between existing and fossil forms.

Buffon took a juster view of this matter; it will be remembered that he concluded his remarks upon the mammoth by saying that many species had doubtless disappeared without leaving any living descendants, while others had left descendants which had become modified.

Lamarck anticipated Lyell in supposing geological changes to have been due almost entirely to the continued operation of the causes which we observe daily at work in nature: thus he writes:—

"Every observer knows that the surface of the earth has changed; every valley has been exalted, thecrooked has been made straight, and the rough places plain; not even is climate itself stable. Hence changed conditions; and these involve changed needs and habits of life; if such changes can give rise to modifications or developments, it is clear that every living body must vary, especially in its outward character, though the variation can only be perceptible after several generations.

"It is not surprising then that so few living species should be represented in the geologic record. It is surprising rather that we should find any living species represented at all.[244]

"Catastrophes have indeed been supposed, and they are an easy way of getting out of the difficulty; but unfortunately, they are not supported by evidence. Local catastrophes have undoubtedly occurred, as earthquakes and volcanic eruptions, of which the effects can be sufficiently seen; but why suppose any universal catastrophe, when the ordinary progress of nature suffices to account for the phenomena? Nature is neverbrusque. She proceeds slowly step by step, and this with occasional local catastrophes will remove all our difficulties."[245]

In his fourth chapter Lamarck points out that animals move themselves, or parts of themselves, not through impulsion or movement communicated to them as from one billiard ball to another, but by reason of a cause which excites their irritability, which cause is within some animals and forms part of them, while it is wholly outside of others.[246]

I should again warn the reader to be on his guard against the opinion that any animals can be said to live if they have no "inward motion" of their own which prompts them to act. We cannot call anything alive which moves only as wind and water may make it move, but without any impulse from within to execute the smallest action and without any capacity of feeling. Such a creature does not look sufficiently like the other things which we call alive; it should be first shown to us, so that we may make up our minds whether the facts concerning it have been truly stated, and if so, what it most resembles; we may then classify it accordingly.

"Some animals change their place by creeping, some by walking, some by running or leaping; others again fly, while others live in the water and swim.

"The origin of these different kinds of locomotion is to be found in the two great wants of animal life: 1, the means of procuring food; 2, the search after mates with a view to reproduction.

"Since then the power of locomotion was a matter affecting their individual self-preservation, as well as that of their race, the existence of the want led to the means of its being gratified."[247]

Lamarck is practically at one with Dr. Erasmus Darwin, that modification will commonly travel along three main lines which spring from the need of reproduction, of procuring food, and (Dr. Darwin has added) the power of self-protection; but Dr. Darwin's treatment of this part of his subject is more lucid andsatisfactory than Lamarck's, inasmuch as he immediately brings forward instances of various modifications which have in each case been due to one of the three main desires above specified, namely, reproduction, subsistence, and self-defence.

Lamarck concludes the chapter with some passages which show that he was alive—as what Frenchman could fail to be after Buffon had written?—to the consequences which must follow from the geometrical ratio of increase, and to the struggle for existence, with consequent survival of the fittest, which must always be one of the conditions of any wild animal's existence. The paragraphs, indeed, on this subject are taken with very little alteration from Buffon's work. As Lamarck's theory is based upon the fact that it is on the nature of these conditions that the habits and consequently the structure of any animal will depend, he must have seen that the shape of many of its organs must vary greatly in correlation to the conditions to which it was subjected in the matter of self-protection. I do not see, then, that there is any substantial difference between the positions taken by Dr. Erasmus Darwin and by Lamarck in this respect.

"Let us conclude," he writes, "by showing the means employed by nature to prevent the number of her creatures from injuring the conservation of what has been produced already, and of the general order which should subsist.[248]

. . . . . . . . . . .

"In consequence of the extremely rapid rate of increaseof the smaller, and especially of the most imperfect, animals, their numbers would become so great as to prove injurious to the conservation of breeds, and to the progress already made towards more perfect organization, unless nature had taken precautions to keep them down within certain fixed limits which she cannot exceed."[249]

This seems to contain, and in a nutshell, as much of the essence of what Mr. Herbert Spencer and Mr. Charles Darwin have termed the survival of the fittest in the struggle for existence, as was necessary for Lamarck's purpose.

To Lamarck, as to Dr. Darwin and Buffon, it was perfectly clear that the facts, that animals have to find their food under varying circumstances, and that they must defend themselves in all manner of varying ways against other creatures which would eat them if they could, were simply some of the conditions of their existence. In saying that the surrounding circumstances—which amount to the conditions of existence—determined the direction in which any plant or animal should be slowly modified, Lamarck includes as a matter of course the fact that the "stronger and better armed should eat the weaker," and thus survive and bear offspring which would inherit the strength and better armour of its parents. Nothing therefore can be more at variance with the truth than to represent Lamarck and the other early evolutionists as ignoring the struggle for existence and the survival of the fittest; these are inevitably implied whenever they use the word "circonstances"or environment, as I will more fully show later on, and are also expressly called attention to by the greater number of them.[250]

"Animals, except those which are herbivorous, prey upon one another; and the herbivorous are exposed to the attacks of the flesh-eating races.

"The strongest and best armed for attack eat the weaker, and the greater kinds eat the smaller. Individuals of the same race rarely eat one another; they war only with other races than their own."[251]

Dr. Darwin here again has the advantage over Lamarck; for he has pointed out how the males contend with one another for the possession of the females, which I do not find Lamarck to have done, though he would at once have admitted the fact. Lamarck continues:—

"The smaller kinds of animals breed so numerously and so rapidly that they would people the globe to the exclusion of other forms of life, if nature had not limited their inconceivable multitude. As, however, they are the prey of a number of other creatures, live but a short time, and perish easily with cold, they are kept always within the proportions necessary for the maintenance both of their own and of other races.[252]

"As regards the larger and stronger animals, they would become dominant, and be injurious to the conservation of many other races, if they could multiply in too great numbers. But as it is, they devour one another, and breed but slowly, and few at a birth, sothat equilibrium is duly preserved among them. Man alone is the unquestionably dominant animal, but men war among themselves, so that it may be safely said the world will never be peopled to its utmost capacity."[253]

In his fifth chapter Lamarck returns to the then existing arrangement and classification of animals.

"Naturalists having remarked that many species, and some genera and even families present characters which as it were isolate them, it has been imagined that these approached or drew further from each other according as their points of agreement or difference seemed greater or less when set down as it were on a chart or map. They regard the small well-marked series which have been styled natural families, as groups which should be placed between the isolated species and their nearest neighbours so as to form a kind of reticulation. This idea, which some of our modern naturalists have held to be admirable, is evidently mistaken, and will be discarded on a profounder and more extended knowledge of organization, and more especially when the distinction has been duly drawn between what is due to the action of special conditions and to general advance of organization."[254]

I take it that Lamarck is here attempting to express what Mr. Charles Darwin has rendered much more clearly in the following excellent passage:—

"It should always be borne in mind what sort of intermediate forms must, on the theory [what theory?], have formerly existed. I have found it difficult when looking at any two species to avoid picturing to myself formsdirectlyintermediate between them. But this is a wholly false view; we should always look for forms intermediate between each species and a common but unknown progenitor; and the progenitor will generally have differed in some respects from all its modified descendants. To give a simple illustration: the fantail and pouter pigeons are both descended from the rock pigeon. If we possessed all the intermediate varieties which have ever existed, we should have an extremely close series, between both and the rock pigeon; but we should have no varieties directly intermediate between the fantail and the pouter; none, for instance, combining a tail somewhat expanded with a crop somewhat enlarged, the characteristic features of these two breeds. These two breeds, moreover, have become so much modified that, if we had no historical or indirect evidence regarding their origin, it would not have been possible to have determined, from a mere comparison of their structure with that of the rockpigeon C. livia, whether they had descended from this species, or from some other allied form, as C. œnas.

"So with natural species, if we look to forms very distinct—for instance, to the horse and the tapir—we have no reason to suppose that links directly intermediate between them ever existed, but between each and an unknown common parent. The common parent will have had in its whole organization much general resemblance to the tapir and the horse; but in some points of structure it may have differed considerably from both, even perhaps more than they differ from each other. Hence in all such cases we should be unable to recognize the parent form of any two or more species, even if we closely compared the structure of the parent with that of its modified descendants, unless at the same time we had a nearly perfect chain of the intermediate links.

. . . . . . . . . . .

"By the theory of natural selection [surely this is a slip for "by the theory of descent with modification"] all living species have been connected with the parent species of each genus, by differences not greater than we see between the natural and domestic varieties of the same species at the present day; and their parent species, now generally extinct, have in their turn been similarly connected with more ancient forms, and so on backwards, always converging to the common ancestor of each great class; so that the number of intermediate and transitional links between all living and extinct species must have been inconceivably great. But assuredly if this theory [the theory of descent withmodification or that of "natural selection"?] be true, such have lived upon the earth."[255]

To return, however, to Lamarck.

"Though Nature," he continues, "in the course of long time has evolved all animals and plants in a true scale of progression, the steps of this scale can be perceived only in the principal groups of living forms; it cannot be perceived in species nor even in genera. The reason of this lies in the extreme diversity of the surroundings in which each different race of animals and plants has existed. These surroundings have often been out of harmony with the growing organization of the plants and animals themselves; this has led to anomalies, and, as it were, digressions, which the mere development of organization by itself could not have occasioned."[256]Or, in other words, to that divergency of type which is so well insisted on by Mr. Charles Darwin.

"It is only therefore the principal groups of animal and vegetable life which can be arranged in a vertical line of descent; species and even genera cannot always be so—for these contain beings whose organization has been dependent on the possession of such and such a special system of essential organs.

"Each great and separate group has its own system of essential organs, and it is these systems which can be seen to descend, within the limits of the group, from their most complex to their simplest form. But each organ, considered individually, does not descend by equally regular gradation; the gradations are less andless regular according as the organ is of less importance, and is more susceptible of modification by the conditions which surround it. Organs of small importance, and not essential to existence, are not always either perfected or degraded at an equal rate, so that in observing all the species of any class we find an organ in one species in the highest degree of perfection, while another organ, which in this same species is impoverished or very imperfect, is highly developed in another species of the same group."[257]

The facts maintained in the preceding paragraph are in great measure supported by Mr. Charles Darwin, who, however, assigns their cause to natural selection.

Mr. Darwin writes, "Ordinary specific characters are more variable than generic;" and again, a little lower down, "The points in which all the species of a genus resemble each other, and in which they differ from allied genera, are called generic characters; and these characters may be attributed to inheritance from a common progenitor, for it can rarely happen that natural selection will have modified several distinct species fitted to more or less widely different habits, in exactly the same manner; and as these so called generic characters have been inherited from before the period when the several species first branched off from their common progenitor, and subsequently have not varied or come to differ in any degree, or only in a slight degree, it is not probable that they should vary at the present day. On the other hand, the points in which species differ from other species of the same genus arecalled specific characters; and as these specific characters have varied and come to differ since the period when the species branched off from a common progenitor, it is probable that they should still often be in some degree variable, or at least more variable than those parts of the organization which have for a very long time remained constant."[258]

The fact, then, that it is specific characters which vary most is agreed upon by both Lamarck and Mr. Darwin. Lamarck, however, maintains that it is these specific characters which are most capable of being affected by the habits of the creature, and that it is for this reason they will be most variable, while Mr. Darwin simply says theyaremost variable, and that, this being so, the favourable variations will be preserved and accumulated—an assertion which Lamarck would certainly not demur to.

"Irregular degrees of perfection," says Lamarck, "and degradation in the less essential organs, are due to the fact that these are more liable than the more essential ones to the influence of external circumstances: these induce corresponding differences in the more outward parts of the animal, and give rise to such considerable and singular difference in species, that instead of being able to arrange them in a direct line of descent, as we can arrange the main groups, these species often form lateral ramifications round about the main groups to which they belong, and in their extreme development are truly isolated."[259]

In his summary of the second chapter of his 'Originof Species,' Mr. Darwin well confirms this when he says, "In large genera the species are apt to be closely, but unequally, allied together, forming little clusters round other species."

"A longer time," says Lamarck, "and a greater influence of surrounding conditions, is necessary in order to modify interior organs. Nevertheless we see that Nature does pass from one system to another without any sudden leap, when circumstances require it, provided the systems are not too far apart. Her method is to proceed from the more simple to the more complex.[260]

"She does this not only in the race, but in the individual." Here Lamarck, like Dr. Erasmus Darwin, shows his perception of the importance of embryology in throwing light on the affinities of animals—as since more fully insisted on by the author of the 'Vestiges of Creation,' and by Mr. Darwin,[261]as well as by other writers. "Breathing through gills is nearer to breathing through lungs than breathing through trachea is. Not only do we see Nature pass from gills to lungs in families which are not too far apart, as may be seen by considering the case of fishes and reptiles; but she does so during the existence of a single individual, which may successively make use both of the one and of the other system. The frog while yet a tadpole breathes through gills; on becoming a frog it breathes through lungs; but we cannot find that Nature in any case passes from trachea to lungs."[262]

Lamarck now rapidly reviews previous classifications, and propounds his own, which stands thus:—I. Vertebrata, consisting of Mammals, Birds, Fishes, and Reptiles. II. Invertebrata, consisting of Molluscs, Centipedes, Annelids, Crustacea, Arachnids, Insects, Worms, Radiata, Polyps, Infusoria.

"The degradation of organism," he concludes, "in this descending scale is not perfectly even, and cannot be made so by any classification, nevertheless there is such evidence of sustained degradation in the principal groups as must point in the direction of some underlying general principle."[263]

Lamarck's sixth chapter is headed "Degradation and Simplification of the Animal Chain as we proceed downwards from the most complex to the most simple Organisms."

"This is a positive fact, and results from the operation of a constant law of nature; but a disturbing cause, which can be easily recognized, varies the regular operation of the law from one end to the other of the chain of life.[264]

"We can see, nevertheless, that special organs become more and more simple the lower we descend; that they become changed, impoverished, and attenuated little by little; that they lose their local centres, and finally become definitely annihilated before we reach the lowest extremity of the chain.[265]

"As has been said already, the degradation of organism is not always regular; such and such an organ often fails or changes suddenly, and sometimesin its changes assumes forms which are not allied with any others by steps that we can recognize. An organ may disappear and reappear several times before being entirely lost: but this is what we might expect, for the cause which has led to the evolution of living organisms has evolved many varieties, due to external influences. Nevertheless, looking at organization broadly, we observe a descending scale."[266]

"If the tendency to progressive development was the only cause which had influenced the forms and organs of animals, development would have been regular throughout the animal chain; but it has not been so: Nature is compelled to submit her productions to an environment which acts upon them, and variation in environment will induce variation in organism: this is the true cause of the sometimes strange deviations from the direct line of progression which we shall have to observe.[267]

"If Nature had only called aquatic beings into existence, and if these beings had lived always in the same climate, in the same kind of water, and at the same depth, the organization of these animals would doubtless have presented an even and regular scale of development. But there has been fresh water, salt water, running and stagnant water, warm and cold climates, an infinite variety of depth: animals exposed to these and other differences in their surroundings have varied in accordance with them.[268]In like manner those animals which have been gradually fitted for living in air instead of water have been subjected toan endless diversity in their surroundings. The following law, then, may be now propounded, namely:—

"That anomalies in the development of organism are due to the influences of the environment and to the habits of the creature.[269]

"Some have said that the anomalies above mentioned are so great as to disprove the existence of any scale which should indicate descent; but the nearer we approach species, the smaller we see differences become, till with species itself we find them at times almost imperceptible."[270]

Lamarck here devotes about seventy pages to a survey of the animal kingdom in its entirety, beginning with the mammals and ending with the infusoria. He points out the manner in which organ after organ disappears as we descend the scale, till we are left with a form which, though presenting all the characteristics of life, has yet no special organ whatever. I am obliged to pass this classification over, but do so very unwillingly, for it is illustrative of Lamarck, both at his best and at his worst.

The seventh chapter is headed—

"On the influence of their surroundings on the actions and habits of animals, and on the effect of these habits and actions in modifying their organization."

"The effect of different conditions of our organization upon our character, tendencies, actions, and even our ideas, has been often remarked, but no attention has yet been paid to that of our actions and habits upon our organization itself. These actions and habits dependentirely upon our relations to the surroundings in which we habitually exist; we shall have occasion, therefore, to see how great is the effect of environment upon organization.

"But for our having domesticated plants and animals we should never have arrived at the perception of this truth; for though the influence of the environment is at all times and everywhere active upon all living bodies, its effects are so gradual that they can only be perceived over long periods of time.[271]

"Taking the chain of life in the inverse order of nature—that is to say, from man downwards—we certainly perceive a sustained but irregular degradation of organism, with an increasing simplicity both in organism and faculties.

"This fact should throw light upon the order taken by nature, but it does not show us why the gradation is so irregular, nor why throughout its extent we find so many anomalies or digressions which have apparently no order at all in their manifold varieties.[272]The explanation of this must be sought for in the infinite diversity of circumstances under which organisms have been developed. On the one hand, there is a tendency to a regular progressive development; on the other, there is a host of widely different surroundings which tend continually to destroy the regularity of development.

"It is necessary to explain what is meant by such expressions as 'the effect of its environment upon the form and organization of an animal.' It must not besupposed that its surroundings directly effect any modification whatever in the form and organization of an animal.[273]Great changes in surroundings involve great changes in the wants of animals, and these changes in their wants involve corresponding changes in their actions. If these new wants become permanent, or of very long duration, the animals contract new habits, which last as long as the wants which gave rise to them.[274]A great change in surroundings, if it persist for a long time, must plainly, therefore, involve the contraction of new habits. These new habits in their turn involve a preference for the employment of such and such an organ over such and such another organ, and in certain cases the total disuse of an organ which is no longer wanted. This is perfectly self-evident.[275]

"On the one hand, new wants have rendered a part necessary, which part has accordingly been created by a succession of efforts: use has kept it in existence, gradually strengthening and developing it till in the end it attains a considerable degree of perfection. On the other, new circumstances having in some cases rendered such or such a part useless, disuse has led to its gradually ceasing to receive the development which the other parts attain to; on this it becomes reduced, and in time disappears.[276]

"Plants have neither actions nor habits properly so called, nevertheless they change in a changed environment as much as animals do. This is due to changes in nutrition, absorption and transpiration, to degrees ofheat, light, and moisture, and to the preponderance over others which certain of the vital functions attain to."

Lamarck is led into the statement that plants have neither actions nor habits, by his theories about the nervous system and the brain. Plain matter-of-fact people will prefer the view taken by Buffon, Dr. Darwin, and, more recently, by Mr. Francis Darwin, that there is no radical difference between plants and animals.

"The differences between well-nourished and ill-nourished plants become little by little very noticeable. If individuals, whether animal or vegetable, are continually ill-fed and exposed to hardships for several generations, their organization becomes eventually modified, and the modification is transmitted until a race is formed which is quite distinct from those descendants of the common parent stock which have been placed in favourable circumstances.[277]In a dry spring the meagre and stunted herbage seeds early. When, on the other hand, the spring is warm but with occasional days of rain, there is an excellent hay-crop. If, however, any cause perpetuates unfavourable circumstances, plants will vary correspondingly, first in appearance and general conditions, and then in several particulars of their actual character, certain organs having received more development than others, these differences will in the course of time become hereditary.[278]

"Nature changes a plant or animal's surroundings gradually—man sometimes does so suddenly. All botanists know that plants vary so greatly underdomestication that in time they become hardly recognizable. They undergo so much change that botanists do not at all like describing domesticated varieties. Wheat itself is an example. Where can wheat be found as a wild plant, unless it have escaped from some neighbouring cultivation? Where are our cauliflowers, our lettuces, to be found wild, with the same characters as they possess in our kitchen gardens?

"The same applies to our domesticated breeds of animals. What a variety of breeds has not man produced among fowls and pigeons, of which we can find no undomesticated examples!"[279]

The foregoing remarks on the effects of domestication seem to have been inspired by those given p. 123 and pp. 168, 169 of this volume.[280]

"Some, doubtless, have changed less than others, owing to their having undergone a less protracted domestication, and a less degree of change in climate; nevertheless, though our ducks and geese, for example, are of the same type as their wild progenitors, they have lost the power of long and sustained flight, and have become in other respects considerably modified.[281]

"A bird, after having been kept five or six years in a cage, cannot on being liberated fly like its brethren which have been always free. Such a change in a single lifetime has not effected any transmissible modification of type; but captivity, continued during manysuccessive generations, would undoubtedly do so. If to the effects of captivity there be added also those of changed climate, changed food, and changed actions for the purpose of laying hold of food, these, united together and become constant, would in the course of time develop an entirely new breed."

This, again, is almost identical with the passage from Buffon,[282]p. 148 of this volume. See also pp. 169, 170.

"Where can our many domestic breeds of dogs be found in a wild state? Where are our bulldogs, greyhounds, spaniels, and lapdogs, breeds presenting differences which, in wild animals, would be certainly called specific? These are all descended from an animal nearly allied to the wolf, if not from the wolf itself. Such an animal was domesticated by early man, taken at successive intervals into widely different climates, trained to different habits, carried by man in his migrations as a precious capital into the most distant countries, and crossed from time to time with other breeds which had been developed in similar ways. Hence our present multiform breeds."[283]

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