Lamarck, the Founder of Evolution Part 11

[74] James Hutton was born at Edinburgh, June 3, 1726, where he died March 26, 1797.

[75] Quoted from Lyell's _Principles of Geology_, eighth edit., p. 17.

[76] _Bulletin Societe Imp. des Naturalistes De Moscou_, xlii. (1869), pt. 1. p. 4, quoted from Geikie's _Geology_, p. 276, footnote.

[77] Suess also, in his _Anlitz_ etc., subst.i.tutes for the folding of the earth's crust by tangential pressure the subsidence by gravity of portions of the crust, their falling in obliging the sea to follow.

Suess also explains the later transgressions of the sea by the progressive acc.u.mulation of sediments which raise the level of the sea by their deposition at its bottom. Thus he believes that the true factor in the deformation of the globe is vertical descent, and not, as Neumayr had previously thought, the folding of the crust.

[78] Bruguiere (1750-1799), a conchologist of great merit. His descriptions of new species were clear and precise. In his paper on the coal mines of the mountains of Cevennes (Choix de Memoires d'Hist. Nat., 1792) he made the first careful study of the coal formation in the Cevennes, including its beds of coal, sandstone, and shale. A. de Jussieu had previously supposed that the immense deposits of coal were due to sudden cataclysms or to one of the great revolutions of the earth during which the seas of the East or West Indies, having been driven as far as into Europe, had deposited on its soil all these exotic plants to be found there, after having torn them up on their way.

But Bruguiere, who is to be reckoned among the early uniformitarians, says that "the capacity for observation is now too well-informed to be contented with such a theory," and he explains the formation of coal deposits in the following essentially modern way:

"The stores of coal, although formed of vegetable substances, owe their origin to the sea. It is when the places where we now find them were covered by its waters that these prodigious ma.s.ses of vegetable substances were gathered there, and this operation of nature, which astonishes the imagination, far from depending on any extraordinary commotion of the globe, seems, on the contrary, to be only the result of time, of an order of things now existing, and especially that of slow changes" (i, pp. 116, 117).

The proofs he brings forward are the horizontality of the beds, both of coal and deposits between them, the marine sh.e.l.ls in the sandstones, the fossil fishes intermingled with the plant remains in the shales; moreover, some of the coal deposits are covered by beds of limestone containing marine sh.e.l.ls which lived in the sea at a very great depth.

The alternation of these beds, the great ma.s.s of vegetable matter which lived at small distances from the soil which conceals them, and the occurrence of these beds so high up, show that at this time Europe was almost wholly covered by the sea, the summits of the Alps and the Pyrenees being then, as he says, so many small islands in the midst of the ocean. He also intimates that the climate when these ferns ("bamboo"

and "banana") lived was warmer than that of Europe at present.

In this essay, then, we see a great advance in correctness of geological observation and reasoning over any previous writers, while its suggestions were appreciated and adopted by Lamarck.

[79] Hooke had previously, in order to explain the presence of tropical fossil sh.e.l.ls in England, indulged in a variety of speculations concerning changes in the position of the axis of the earth's rotation, "a s.h.i.+fting of the earth's centre of gravity a.n.a.logous to the revolutions of the magnetic pole, etc." (Lyell's _Principles_). See also p. 132.

[80] Cuvier, in a footnote to his _Discours_ (sixth edition, p. 49), in referring to this view, states that it originated with Rodig (_La Physique_, p. 106, Leipzig, 1801) and De Maillet (_Telliamed_, tome ii., p. 169), "also an infinity of new German works." He adds: "M. de Lamarck has recently expanded this system in France at great length in his _Hydrogeologie_ and in his _Philosophie zoologique_." Is the Rodig referred to Ih. Chr. Rodig, author of _Beitrage zur Naturwissenschaft_ (Leipzig, 1803. 8^o)? We have been unable to discover this view in De Maillet; Cuvier's reference to p. 169 is certainly incorrect, as quite a different subject is there discussed.

CHAPTER IX

LAMARCK THE FOUNDER OF INVERTEBRATE PALaeONTOLOGY

It was fortunate for palaeontology that the two greatest zoologists of the end of the eighteenth and the beginning of the nineteenth centuries, Lamarck and Cuvier, lived in the Paris basin, a vast cemetery of corals, sh.e.l.ls, and mammals; and not far from extensive deposits of cretaceous rocks packed with fossil invertebrates. With their then unrivalled knowledge of recent or existing forms, they could restore the a.s.semblages of extinct animals which peopled the cretaceous ocean, and more especially the tertiary seas and lakes.

Lamarck drew his supplies of tertiary sh.e.l.ls from the tertiary beds situated within a radius of from twenty-five to thirty miles from the centre of Paris, and chiefly from the village of Grignon, about ten miles west of Paris, beyond Versailles, and still a rich collecting ground for the students of the Museum and Sorbonne. He acknowledges the aid received from Defrance,[81] who had already collected at Grignon five hundred species of fossil sh.e.l.ls, three-fourths of which, he says, had not then been described.

Lamarck's first essay ("_Sur les fossiles_") on fossils in general was published at the end of his _Systeme des Animaux sans Vertebres_ (pp. 401-411), in 1801, a year before the publication of the _Hydrogeologie_. "I give the name _fossils_," he says, "to remains of living beings, changed by their long sojourn in the earth or under water, but whose forms and structure are still recognizable.

"From this point of view, the bones of vertebrate animals and the remains of testaceous molluscs, of certain crustacea, of many echinoderms, coral polyps, when after having been for a long time buried in the earth or hidden under the sea, will have undergone an alteration which, while changing their substance, has nevertheless destroyed neither their forms, their figures, nor the special features of their structures."

He goes on to say that the animal parts having been destroyed, the sh.e.l.l remains, being composed of calcareous matter. This sh.e.l.l, then, has lost its l.u.s.tre, its colors, and often even its nacre, if it had any; and in this altered condition it is usually entirely white. In some cases where the sh.e.l.ls have remained for a long period buried in a mud of some particular color, the sh.e.l.l receives the same color.

"In France, the fossil sh.e.l.ls of Courtagnon near Reims, Grignon near Versailles, of what was formerly Touraine, etc., are almost all still in this calcareous state, having more or less completely lost their animal parts--namely, their l.u.s.tre, their peculiar colors, and their nacre.

"Other fossils have undergone such an alteration that not only have they lost their animal portion, but their substance has been changed into a silicious matter. I give to this second kind of fossil the name of _silicious fossils_, and examples of this kind are the different oysters ('des ostracites'), many terebratulae ('des terebratulites'), trigoniae, ammonites, echinites, encrinites, etc.

"The fossils of which I have just spoken are in part buried in the earth, and others lie scattered over its surface. They occur in all the exposed parts of our globe, in the middle even of the largest continents, and, what is very remarkable, they occur on mountains up to very considerable alt.i.tudes. In many places the fossils buried in the earth form banks extending several leagues in length."[82]

Conchologists, he says, did not care to collect or study fossil sh.e.l.ls, because they had lost their l.u.s.tre, colors, and beauty, and they were rejected from collections on this account as "dead" and uninteresting.

"But," he adds, "since attention has been drawn to the fact that these fossils are extremely valuable _monuments_ for the study of the revolutions which have taken place in different regions of the earth, and of the changes which the beings living there have themselves successively undergone (in my lectures I have always insisted on these considerations), consequently the search for and study of fossils have excited special interest, and are now the objects of the greatest interest to naturalists."

Lamarck then combats the views of several naturalists, undoubtedly referring to Cuvier, that the fossils are extinct species, and that the earth has pa.s.sed through a general catastrophe (_un boulevers.e.m.e.nt universel_) with the result that a mult.i.tude of species of animals and plants were consequently absolutely lost or destroyed, and remarks in the following telling and somewhat derisive language:

"A universal catastrophe (_boulevers.e.m.e.nt_) which necessarily regulates nothing, mixes up and disperses everything, is a very convenient way to solve the problem for those naturalists who wish to explain everything, and who do not take the trouble to observe and investigate the course followed by nature as respects its production and everything which const.i.tutes its domain. I have already elsewhere said what should be thought of this so-called universal overturning of the globe; I return to fossils.

"It is very true that, of the great quant.i.ty of fossil sh.e.l.ls gathered in the different countries of the earth, there are yet but a very small number of species whose living or marine a.n.a.logues are known. Nevertheless, although this number may be very small, which no one will deny, it is enough to suppress the universality announced in the proposition cited above.

"It is well to remark that among the fossil sh.e.l.ls whose marine or living a.n.a.logues are not known, there are many which have a form closely allied to sh.e.l.ls of the same genera known to be now living in the sea. However, they differ more or less, and cannot be rigorously regarded as the same species as those known to be living, since they do not perfectly resemble them. These are, it is said, extinct species.

"I am convinced that it is possible never to find, among fresh or marine sh.e.l.ls, any sh.e.l.ls perfectly similar to the fossil sh.e.l.ls of which I have just spoken. I believe I know the reason; I proceed to succinctly indicate, and I hope that it will then be seen, that although many fossil sh.e.l.ls are different from all the marine sh.e.l.ls known, this does not prove that the species of these sh.e.l.ls are extinct, but only that these species have changed as the result of time, and that actually they have different forms from those individuals whose fossil remains we have found."

Then he goes on in the same strain as in the opening discourse, saying that nothing terrestrial remains constant, that geological changes are continually occurring, and that these changes produce in living organisms a diversity of habits, a different mode of life, and as the result modifications or developments in their organs and in the shape of their parts.

"We should still realize that all the modifications which the organism undergoes in its structure and form as the result of the influence of circ.u.mstances which would influence this being, are propagated by generation, and that after a long series of ages not only will it be able to form new species, new genera, and even new orders, but also each species will even necessarily vary in its organization and in its forms.

"We should not be more surprised then if, among the numerous fossils which occur in all the dry parts of the globe and which offer us the remains of so many animals which have formerly existed, there should be found so few of which we know the living a.n.a.logues. If there is in this, on the contrary, anything which should astonish us, it is to find that among these numerous fossil remains of beings which have lived there should be known to us some whose a.n.a.logues still exist, from a germ to a vast mult.i.tude of living forms, of different and ascending grades of perfection, ending in man.

"This fact, as our collection of fossils proves, should lead us to suppose that the fossil remains of the animals whose living a.n.a.logues we know are the less ancient fossils. The species to which each of them belongs had doubtless not yet time to vary in any of its forms.

"We should, then, never expect to find among the living species the totality of those that we meet with in the fossil state, and yet we cannot conclude that any species can really be lost or extinct. It is undoubtedly possible that among the largest animals some species have been destroyed as a result of the multiplication of man in the regions where they live. But this conjecture cannot be based on the consideration of fossils alone; we can only form an opinion in this respect when all the inhabited parts of the globe will have become perfectly known."

Lamarck did not have, as we now have, a knowledge of the geological succession of organic forms. The comparatively full and detailed view which we possess of the different vast a.s.semblages of plant and animal life which have successively peopled the surface of our earth is a vision on which his eyes never rested. His slight, piecemeal glimpse of the animal life of the Paris Basin, and of the few other extinct forms then known, was all he had to depend upon or reason from. He was not disposed to believe that the thread of life once begun in the earliest times could be arbitrarily broken by catastrophic means; that there was no relation whatever between the earlier and later faunas. He utterly opposed Cuvier's view that species once formed could ever be lost or become extinct without ancestors or descendants. He on the contrary believed that species underwent a slow modification, and that the fossil forms are the ancestors of the animals now living. Moreover, Lamarck was the inventor of the first genealogical tree; his phylogeny, in the second volume of his _Philosophie zoologique_ (p. 463), proves that he realized that the forms leading up to the existing ones were practically extinct, as we now use the word. Lamarck in theory was throughout, as Houssay well says, at one with us who are now living, but a century behind us in knowledge of the facts needed to support his theory.

In this first published expression of his views on palaeontology, we find the following truths enumerated on which the science is based: (1) The great length of geological time; (2) The continuous existence of animal life all through the different geological periods without sudden total extinctions and as sudden recreations of new a.s.semblages; (3) The physical environment remaining practically the same throughout in general, but with (4) continual gradual but not catastrophic changes in the relative distribution of land and sea and other modifications in the physical geography, changes which (5) caused corresponding changes in the habitat, and (6) consequently in the habits of the living beings; so that there has been all through geological history a slow modification of life-forms.

Thus Lamarck's idea of creation is _evolutional_ rather than _uniformitarian_. There was, from his point of view, not simply a uniform march along a dead level, but a progression, a change from the lower or generalized to the higher or specialized--an evolution or unfolding of organic life. In his effort to disprove catastrophism he failed to clearly see that species, as we style them, became extinct, though really the changes in the species practically amounted to extinctions of the earlier species as such. The little that was known to Lamarck at the time he wrote, prevented his knowing that species became extinct, as we say, or recognizing the fact that while some species, genera, and even orders may rise, culminate, and die, others are modified, while a few persist from one period to another. He did, however, see clearly that, taking plant and animal life as a whole, it underwent a slow modification, the later forms being the descendants of the earlier; and this truth is the central one of modern palaeontology.

Lamarck's first memoir on fossil sh.e.l.ls, in which he described many new species, was published in 1802, after the appearance of his _Hydrogeologie_, to which he refers. It was the first of a series of descriptive papers, which appeared at intervals from 1802 to 1806. He does not fail to open the series of memoirs with some general remarks, which prove his broad, philosophic spirit, that characterizing the founder of a new science. He begins by saying that the fossil forms have their a.n.a.logues in the tropical seas. He claims that there was evident proof that these molluscs could not have lived in a climate like that of places in which they now occur, instancing _Nautilius pompilius_, which now lives in the seas of warm countries; also the presence of exotic ferns, palms, fossil amber, fossil gum elastic, besides the occurrence of fossil crocodiles and elephants both in France and Germany.[83]

Hence there have been changes of climate since these forms flourished, and, he adds, the intervals between these changes of climate were stationary periods, whose duration was practically without limit. He a.s.signs a duration to these stationary or intermediate periods of from three to five million years each--"a duration infinitely small relative to those required for all the changes of the earth's surface."

He refers in an appreciative way to the first special treatise on fossil sh.e.l.ls ever published, that of an Englishman named Brander,[84] who collected the sh.e.l.ls "out of the cliffs by the sea-coast between Christ Church and Lymington, but more especially about the cliffs by the village of Hordwell," where the strata are filled with these fossils.

Lamarck, working upon collections of tertiary sh.e.l.ls from Grignon and also from Courtagnon near Reims, with the aid of Brander's work showed that these beds, not known to be Eocene, extended into Hamps.h.i.+re, England; thus being the first to correlate by their fossils, though in a limited way to be sure, the tertiary beds of France with those of England.

How he at a later period (1805) regarded fossils and their relations to geology may be seen in his later memoirs, _Sur les Fossiles des environs de Paris_.[85]

"The determination of the characters, both generic and specific, of animals of which we find the fossil remains in almost all the dry parts of the continents and large islands of our globe will be, from several points of view, a thing extremely useful to the progress of natural history. At the outset, the more this determination is advanced, the more will it tend to complete our knowledge in regard to the species which exist in nature and of those which have existed, as it is true that some of them have been lost, as we have reason to believe, at least as concerns the large animals. Moreover, this same determination will be singularly advantageous for the advancement of geology; for the fossil remains in question may be considered, from their nature, their condition, and their situation, as authentic monuments of the revolutions which the surface of our globe has undergone, and they can throw a strong light on the nature and character of these revolutions."

This series of papers on the fossils of the Paris tertiary basin extended through the first eight volumes of the _Annales_, and were gathered into a volume published in 1806. In his descriptions his work was comparative, the fossil species being compared with their living representatives. The thirty plates, containing 483 figures representing 184 species (exclusive of those figured by Brard), were afterwards published, with the explanations, but not the descriptions, as a separate volume in 1823.[86] This (the text published in 1806) is the first truly scientific palaeontological work ever published, preceding Cuvier's _Oss.e.m.e.ns fossiles_ by six years.

When we consider Lamarck's--at his time unrivalled--knowledge of molluscs, his philosophical treatment of the relations of the study of fossils to geology, his correlation of the tertiary beds of England with those of France, and his comparative descriptions of the fossil forms represented by the existing sh.e.l.ls, it seems not unreasonable to regard him as the founder of invertebrate palaeontology, as Cuvier was of vertebrate or mammalian palaeontology.

We have entered the claim that Lamarck was one of the chief founders of palaeontology, and the first French author of a genuine, detailed palaeontological treatise. It must be admitted, therefore, that the statement generally made that Cuvier was the founder of this science should be somewhat modified, though he may be regarded as the chief founder of vertebrate palaeontology.

In this field, however, Cuvier had his precursors not only in Germany and Holland, but also in France.

Our information as to the history of the rise of vertebrate palaeontology is taken from Blainville's posthumous work ent.i.tled _Cuvier et Geoffroy Saint-Hilaire_.[87] In this work, a severe critical and perhaps not always sufficiently appreciative account of Cuvier's character and work, we find an excellent history of the first beginnings of vertebrate palaeontology. Blainville has little or nothing to say of the first steps in invertebrate palaeontology, and, singularly enough, not a word of Lamarck's principles and of his papers and works on fossil sh.e.l.ls--a rather strange oversight, because he was a friend and admirer of Lamarck, and succeeded him in one of the two departments of invertebrates created at the Museum d'Histoire Naturelle after Lamarck's death.