Page:Darwinism by Alfred Wallace 1889.djvu/28

 nature and origin of species. They render it clear that, notwithstanding the vast knowledge and ingenious reasoning of Lamarck, and the more general exposition of the subject by the author of the Vestiges of Creation, the first step had not been taken towards a satisfactory explanation of the derivation of any one species from any other. Such eminent naturalists as Geoffroy Saint Hilaire, Dean Herbert, Professor Grant, Von Buch, and some others, had expressed their belief that species arose as simple varieties, and that the species of each genus were all descended from a common ancestor; but none of them gave a clue as to the law or the method by which the change had been effected. This was still "the great mystery." As to the further question—how far this common descent could be carried; whether distinct families, such as crows and thrushes, could possibly have descended from each other; or, whether all birds, including such widely distinct types as wrens, eagles, ostriches, and ducks, could all be the modified descendants of a common ancestor; or, still further, whether mammalia, birds, reptiles, and fishes, could all have had a common origin;—these questions had hardly come up for discussion at all, for it was felt that, while the very first step along the road of "transmutation of species" (as it was then called) had not been made, it was quite useless to speculate as to how far it might be possible to travel in the same direction, or where the road would ultimately lead to.

It is clear, then, that what was understood by the "origin" or the "transmutation" of species before Darwin's work appeared, was the comparatively simple question whether the allied species of each genus had or had not been derived from one another and, remotely, from some common ancestor, by the ordinary method of reproduction and by means of laws and conditions still in action and capable of being thoroughly investigated. If any naturalist had been asked at that day whether, supposing it to be clearly shown that all the different species of each genus had been derived from some one ancestral species, and that a full and complete explanation were to be given of how each minute difference in form, colour, or structure might have originated, and how the