Lamarck, the Founder of Evolution Part 25

"I have seen them, these animals, and I believe in the conformity of their resemblance with the individuals of the same species which live to-day. Thus the animals which the Egyptians worshipped and embalmed two or three thousand years ago are still in every respect similar to those which actually live in that country.

"But it would be a.s.suredly very singular that this should be otherwise; for the position of Egypt and its climate are still or very nearly the same as at former times. Therefore the animals which live there have not been compelled to change their habits.

"There is, then, nothing in the observation which has just been reported which should be contrary to the considerations which I have expressed on this subject; and which especially proves that the animals of which it treats have existed during the whole period of nature. It only proves that they have existed for two or three thousand years; and every one who is accustomed to reflect, and at the same time to observe that which nature shows us of the monuments of its antiquity, readily appreciates the value of a duration of two or three thousand years in comparison with it.

"Hence, as I have elsewhere said, it is sure that this appearance of the stability of things in nature will always be mistaken by the average of mankind for the reality; because in general people only judge of everything relatively to themselves.

"For the man who observes, and who in this respect only judges from the changes which he himself perceives, the intervals of these changes are _stationary conditions_ (_etats_) which should appear to be limitless, because of the brevity of life of the individuals of his species. Thus, as the records of his observations and the notes of facts which he has consigned to his registers only extend and mount up to several thousands of years (three to five thousand years), which is an infinitely small period of time relatively to those which have sufficed to bring about the great changes which the surface of the globe has undergone, everything seems _stable_ to him in the planet which he inhabits, and he is inclined to reject the monuments heaped up around him or buried in the earth which he treads under his feet, and which surrounds him on all sides.[174]

"It seems to me [as mistaken as] to expect some small creatures which only live a year, which inhabit some corner of a building, and which we may suppose are occupied with consulting among themselves as to the tradition, to p.r.o.nounce on the duration of the edifice where they occur: and that going back in their paltry history to the twenty-fifth generation, they should unanimously decide that the building which serves to shelter them is eternal, or at least that it has always existed; because it has always appeared the same to them; and since they have never heard it said that it had a beginning. Great things (_grandeurs_) in extent and in duration are relative.[175]

"When man wishes to clearly represent this truth he will be reserved in his decisions in regard to stability, which he attributes in nature to the state of things which he observes there.[176]

"To admit the insensible change of species, and the modifications which individuals undergo as they are gradually forced to vary their habits or to contract new ones, we are not reduced to the unique consideration of too small s.p.a.ces of time which our observations can embrace to permit us to perceive these changes; for, besides this induction, a quant.i.ty of facts collected for many years throws sufficient light on the question that I examine, so that does not remain undecided; and I can say now that our sciences of observation are too advanced not to have the solution sought for made evident.

"Indeed, besides what we know of the influences and the results of heteroc.l.i.te fecundations, we know positively to-day that a forced and long-sustained change, both in the habits and mode of life of animals, and in the situation, soil, and climate of plants, brings about, after a sufficient time has elapsed, a very remarkable change in the individuals which are exposed to them.

"The animal which lives a free, wandering life on plains, where it habitually exercises itself in running swiftly; the birds whose needs (_besoins_) require them unceasingly to traverse great s.p.a.ces in the air, finding themselves enclosed, some in the compartments of our menageries or in our stables, and others in our cages or in our poultry yards, are submitted there in time to striking influences, especially after a series of regenerations under the conditions which have made them contract new habits. The first loses in large part its nimbleness, its agility; its body becomes stouter, its limbs diminish in power and suppleness, and its faculties are no longer the same. The second become clumsy; they are unable to fly, and grow more fleshy in all parts of their bodies.

"Behold in our stout and clumsy horses, habituated to draw heavy loads, and which const.i.tute a special race by always being kept together--behold, I say, the difference in their form compared with those of English horses, which are all slender, with long necks, because for a long period they have been trained to run swiftly: behold in them the influence of a difference of habit, and judge for yourselves. You find them, then, such as they are in some degree in nature. You find there our c.o.c.k and our hen in the condition we have [made] them, as also the mixed races that we have formed by mixed breeding between the varieties produced in different countries, or where they were so in the state of domesticity. You find there likewise our different races of domestic pigeons, our different dogs, etc. What are our cultivated fruits, our wheat, our cabbage, our lettuce, etc., etc., if they are not the result of changes which we ourselves have effected in these plants, in changing by our culture the conditions of their situation? Are they now found in this condition in nature? To these incontestable facts add the considerations which I have discussed in my _Recherches sur les Corps vivans_ (p. 56 _et suiv._), and decide for yourselves.

"Thus, among living bodies, nature, as I have already said, offers only in an absolute way individuals which succeed each other genetically, and which descend one from the other. So the _species_ among them are only relative, and only temporary.

"Nevertheless, to facilitate the study and the knowledge of so many different bodies it is useful to give the name of _species_ to the entire collection of individuals which are alike, which reproduction perpetuates in the same condition as long as the conditions of their situation do not change enough to make their habits, their character, and their form vary.

"Such is, citizens, the exact sketch of that which goes on in nature since she has existed, and of that which the observation of her acts has alone enabled us to discover. I have fulfilled my object if, in presenting to you the results of my researches and of my experience, I have been able to disclose to you that which in your studies of this kind deserves your special attention.

"You now doubtless conceive how important are the considerations which I have just exposed to you, and how wrong you would be if, in devoting yourself to the study of animals or of plants, you should seek to see among them only the multiplied distinctions that we have been obliged to establish; in a word, if you should confine yourselves to fixing in your memory the variable and indefinite nomenclature which is applied to so many different bodies, instead of studying Nature herself--her course, her means, and the constant results that she knows how to attain."

On the next fly page are the following words: _Esquisse d'une Philosophie zoologique_.

IV. _Lamarck's Views as published in 1806._[177]

"Those who have observed much and have consulted the great collections, have been able to convince themselves that as gradually as the circ.u.mstances of their habitat, of exposure to their surroundings, of climate, food, mode of living, etc., have changed, the characters of size, form, of proportion between the parts, of color, of consistence, of duration, of agility, and of industry have proportionately changed.

"They have been able to see, as regards the animals, that the more frequent and longer sustained use of any organ gradually strengthens this organ, develops it, enlarges it, and gives it a power proportional to the length of time it has been used; while the constant lack of use of such an organ insensibly weakens it, causes it to deteriorate, progressively diminishes its faculties, and tends to make it waste away.[178]

"Finally, it has been remarked that all that nature has made individuals to acquire or lose by the sustained influence of circ.u.mstances where their race has existed for a long time, she has preserved by heredity in the new individuals which have originated from them (_elle le conserve par la generation aux nouveaux individus qui en proviennent_). These verities are firmly grounded, and can only be misunderstood by those who have never observed and followed nature in her operations.

"Thus we are a.s.sured that that which is taken for _species_ among living bodies, and that all the specific differences which distinguish these natural productions, have no absolute _stability_, but that they enjoy only a relative _stability_; which it is very important to consider in order to fix the limits which we must establish in the determination of that which we must call _species_.

"It is known that different places change in nature and character by reason of their position, their 'composition' [we should say geological structure or features], and their climate; that which is easily perceived in pa.s.sing over different places distinguished by special characteristics; behold already a cause of variation for the natural productions which inhabit these different places. But that which is not sufficiently known, and even that which people refuse to believe, is that each place itself changes after a time, in exposure, in climate, in nature, and in character, although with a slowness so great in relation to our period of time that we attribute to it a perfect _stability_.

"Now, in either case, these changed places proportionately change the circ.u.mstances relative to the living bodies which inhabit them, and these produce again other influences on those same bodies.

"We see from this that if there are extremes in these changes there are also gradations (_nuances_), that is to say, steps which are intermediate, and which fill up the interval; consequently there are also gradations in the differences which distinguish that which we call _species_.

"Indeed, as we constantly meet with such shades (or intermediate steps) between these so-called _species_, we find ourselves forced to descend to the minutest details to find any distinctions; the slightest peculiarities of form, of color, of size, and often even of differences only perceived in the aspect of the individual compared with other individuals which are related to it the more by their relations, are seized upon by naturalists to establish specific differences; so that, the slightest varieties being reckoned as species, our catalogues of species grow infinitely great, and the name of the productions of nature of the most interest to us are, so to speak, buried in these enormous lists, become very difficult to find, because now the objects are mostly only determined by characters which our senses can scarcely enable us to perceive.

"Meanwhile we should remember that nothing of all this exists in nature; that she knows neither cla.s.ses, orders, genera, nor species, in spite of all the foundation which the portion of the natural series which our collection contains has seemed to afford them; and that of organic or living bodies there are, in reality, only individuals, and among different races which gradually pa.s.s (_nuancent_) into all degrees of organization" (p. 14).

On p. 70 he speaks of the animal chain from monad to man, ascending from the most simple to the most complex. The monad is the most simple, the most like a germ of living bodies, and from its nature pa.s.ses to the volvoces, proteus, vibrios; from them nature arrives at the production of "polypes rotiferes"--and then at "Radiaires," worms, Arachnida, Crustacea, and Cirrhipedes.

FOOTNOTES:

[162] _Discours d'ouverture du Cours de Zoologie donne dans le Museum national d'Histoire naturelle, le 21 floreal, an 8 de la Republique_ (1800). Floreal is the name adopted by the National Convention for the eighth month of the year. In the years of the Republic 1 to 7 it extended from April 20 to May 19 inclusive, and in the years 8 to 13 from April 21 to May 20 (_Century Cyclopedia of Names_). The lecture, then, in which Lamarck first presented his views was delivered on some day between April 21 and May 20, 1800.

[163] Lamarck by the word _generation_ implies heredity. He nowhere uses the word _heredite_.

[164] "L'oiseau que le besoin attire sur l'eau pour y trouver la proie qui le fait vivre, ecarte les doigts de ses pieds lorsqu'il veut frapper l'eau et se mouvoir a sa surface" (p. 13). If the word _veut_ has suggested the doctrine of appetency in meaning has been pushed too far by the critics of Lamarck.

[165] This he already touched upon in his _Memoires de Physique et d'Histoire naturelle_ (p. 342).

[166] _Systeme des Animaux sans Vertebres_, pp. 16 and 17.

[167] I have cited the incontestable proofs in my _Hydrogeologie_, and I have the conviction that one day all will be compelled to accept these great truths.

[168] _Ranunculus aquaticus capillaceus_ (Tournef., p. 291).

[169] _Ranunculus aquaticus_ (folio rotundo et capillaceo, Tournef., p. 291).

[170] _Gramen junceum_, etc. (Moris, hist. 3, sec. 8, t. 9, f. 4).

[171] _Discours d'ouverture d'un Cours de Zoologie, p.r.o.nonce en prairial, an XI, au Museum d'Histoire naturelle, sur la question, Qu'est-ce que l'espece parmi les corps vivans?_ (1803).

[172] _Recherches sur l'Organisation des Corps vivans_, p. 9.

[173] "See at the end of this discourse the sketch of a _Philosophie zoologique_ relative to this subject." [This sketch was not added--only the t.i.tle at the end of the book.]

[174] See the _Annales du Museum d'Hist. nat._, IV^e cahier. 1., 1802, pp. 302, 303: _Memoires sur les Fossiles des Environs de Paris_, etc. He repeats in his _Discours_ what he wrote in 1802 in the _Annales_.

[175] _Ibid._ This is repeated from the article in the _Annales_.

[176] _Ibid._ "See my _Recherches sur les Corps vivans_" (Appendix, p. 141).

[177] _Discours d'Ouverture du Cours des Animaux sans Vertebres, p.r.o.nonce dans le Museum d'Histoire naturelle en mai 1806._ (No imprint.

8^o, pp. 108.) Only the most important pa.s.sages are here translated.

[178] "We know that all the forms of organs compared to the uses of these same organs are always perfectly adapted. But there is a common error in this connection, since it is thought that the forms of organs have caused their functions (_en ont amene l'emploi_), whereas it is easy to demonstrate by observation that it is the uses (_usages_) which have given origin to the forms of organs."

CHAPTER XVII