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AN HISTORICAL SKETCH OF THE RECENT PROGRESS OF

OPINION ON THE ORIGIN OF SPECIES.

I WILL here attempt to give a brief, but imperfect sketch of the progress of opinion on the Origin of Species. The great majority of naturalists believe that species are immutable productions, and have been separately created. This view has been ably maintained by many authors. Some few naturalists, on the other hand, believe that species undergo modification, and that the existing forms of life have descended by true generation from pre-existing forms. Passing over authors from the classical period to that of Buffon, with whose writings I am not familiar, Lamarck was the first man whose conclusions on this subject excited much attention. This justly-celebrated naturalist first published his views in 1801, and he much enlarged them in 1809 in his Philosophie Zoologique, and subsequently, in 1815, in his Introduction to his

Hist. Nat. des Animaux sans Vertèbres.' In these works he upholds the doctrine that all species, including man, are descended from other species. He first did the eminent service of arousing attention to the probability of all change in the organic as well as in the inorganic world being the result of law, and not of miraculous interposition. Lamarck seems to have been chiefly led to his conclusion on the gradual change of species, by the difficulty of distinguishing species and varieties, by the almost perfect gradation of forms in certain organic groups, and by the analogy of domestic productions. With respect to the means of modification, he attributed something to the direct action of the physical conditions of life, something to the crossing of already existing forms, and much to use and disuse, that is, to the effects of habit. To this latter agency he seems to attribute all the beautiful adaptations in nature ;-—such as the long neck of the giraffe for browsing on the branches of trees. But he likewise believed in a law of progressive development ; and as all the forms of life thus tended to progress, in order to account for the existence at the present day of

very simple productions, he maintained that such forms were now spontaneously generated.*

Geoffroy Saint Hilaire, as is stated in his ' Life,' written by his son, 'suspected, as early as 1795, that what we call species are various degenerations of the same type. It was not until 1828 that he published his conviction that the same forms have not been perpetuated since the origin of all things. Geoffroy seems to have relied chiefly on the conditions of life, or the monde ambiant," as the cause of change. He was cautious in drawing conclusions, and did not believe that existing species are now undergoing modification ; and, as his son adds, “ C'est donc un problème à réserver entièrement à l'avenir, supposé même que l'avenir doive avoir prise sur lui.”

In England the Hon. and Rev. W. Herbert, afterward: Dean of Manchester, in the fourth volume of the 'Horticultural Transactions,' 1822, and in his work on the Amaryllidaceæ' (1837, p. 19, 339), declares that "horticultural experiments have established, beyond the possibility of refutation, that botanical species are only a higher and more permanent class of varieties.” He extends the same view to animals. The Dean believes that single species of each genus were created in an originally highly plastic condition, and that these have produced, chiefly by intercrossing, but likewise by variation, all our existing species.

In 1826, Professor Grant, in the concluding paragraph in his well-known paper (Edinburgh Philosophical Journal, vol. xiv. p. 283) on the Spongilla, clearly declares his belief that species are descended from other species, and that they become improved in the course of modification.

I have taken the date of the first publication of Lamarck from Isid. Geoffroy Saint Hilaire's (* Hist. Nat. Generale,' tom. ii. p. 403, 1859) excellent history of opinion on this subject. In this work a full account is given of Buffon's fluctuating conclusions on the same subject. It is curious how largely my grandfather, Dr. Erasmus Darwin, anticipated the erroneous grounds of opinion, and the views of Lamarck, in his ' Zoonomia ' (vol. i. p. 500-510), published in 1794. According to Isid. Geoffroy there is no doubt that Goethe was an extreme partisan of similar views, as shown in the Introduction to a work written in 1794 and 1795, but not published till long afterwards. It is rather à singular instance of the manner in which similar views arise at about the same period, that Goethe in Germany, Dr. Darwin in England, and Geoffroy Saint . Hilaire (as we shall immediately see) in France, came to the same conclusion on the origin of species, in the years 1794-5.

This same view was given in his 55th Lecture, published in the · Lancet' in 1834.

In 1831 Mr. Patrick Matthew published his work on • Naval Timber and Aboriculture,' in which he gives precisely the same view on the origin of species as that (presently to be alluded to) propounded by Mr. Wallace and myself in the ‘Linnean Journal,' and as that enlarged on in the present volume. Unfortunately the view was given by Mr. Matthew very briefly in scattered passages in an Appendix to a work on a different subject, so that it remained unnoticed until Mr. Matthew himself drew attention to it in the ' Gardener's Chronicle, on April 7th, 1860. The differences of Mr. Matthew's view from mine are not of much importance: he seems to consider that althe world was nearly depopulated at successive periods, and then re-stocked ; and he gives, as an alternative, that new forms may be generated “ without the presence of any mould or germ of former aggregates.” I am not sure that I understand some passages; but it seems that he attributes much influence to the direct action of the conditions of life. He clearly saw, however, the full force of the principle of natural selection. In answer to a letter of mine (published in Gard. Chron., April 13th), fully acknowledging that Mr. Matthew had anticipated me, he with generous candour wrote a letter (Gard. Chron. May 12th) containing the following passage :-"To me the conception of this law of Nature came intuitively as a self-evident fact, almost without an effort of concentrated thought. Mr. Darwin here seems to have more merit in the discovery than I have had ; to me it did not appear a discovery. He seems to have worked it out by inductive reason, slowly and with due caution to have made his way synthetically from fact to fact onwards; while with me it was by a general glance at the scheme of Nature that I estimated this select production of species as an à priori recognisable fact-an axiom requiring only to be pointed out to be admitted by unprejudiced minds of sufficient grasp.”

Rafinesque, in his “New Flora of North America,' published in 1836, wrote (p. 6) as follows :—“All species might have been varieties once, and many varieties are gradually becoming species by assuming constant and peculiar characters : ” but farther on (p. 18) he adds, except the original types or ancestors of the genus."

In 1843-44 Professor Haldeman (Boston Journal of Nat. Hist. U. States, vol. iv. p. 468) has ably given the

arguments for and against the hypothesis of the development and modification of species : he seems to lean towards the side of change.

The ' Vestiges of Creation' appeared in 1844. In the tenth and much improved edition (1853) the anonymous author says (p. 155) :-“ The proposition determined on after much consideration is, that the several series of animated beings, from the simplest and oldest up to the highest and most recent, are, under the providence of God, the results, first, of an impulse which has been imparted to the forms of life, advancing them, in definite times, by generation, through grades of organisation terminating in the highest dicotyledons and vertebrata, these grades being few in number, and generally marked by intervals of organic character, which we find to be a practical difficulty in ascertaining affinities; second, of another impulse connected with the vital forces, tending, in the course of generations, to modify organic structures in accordance with external circumstances, as food, the nature of the habitat, and the meteoric agencies, these being the 'adaptations of the natural theologian.” The author apparently believes that organisation progresses by sudden leaps, but that the effects produced by the conditions of life are gradual. He argues with much force on general grounds that species are not immutable productions. But I cannot see how the two supposed " impulses ” account in a scientific sense for the numerous and beautiful coadaptations which we see throughout nature; I cannot see that we thus gain any insight how, for instance, a woodpecker has become adapted to its peculiar habits of life. The work, from its powerful and brilliant style, though displaying in the earlier editions little accurate knowledge and great want of scientific caution, immediately had a very wide circulation. In my opinion it has done excellent service in calling in this country attention to the subject, in removing prejudice, and in thus preparing the ground for the reception of analogous views.

In 1846 a veteran geologist M. J. d'Omalius d'Halloy published in an excellent, though short paper (Bulletins del 'Acad. Roy. Bruxelles,' tom. xiii. p. 581), his opinion that it is more probable that new species have been produced by descent with modification, than that they have been separately created : the author first promulgated this opinion in 1831.

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