But, whatever may thus appear from the point of view of strict logic, it is abundantly evident that in common estimation the assumed fact of Organic transformation is the foundation-stone of Evolutionary[{144}] systems of every kind. And not unnaturally; for here at last we have something with which Science can deal, strictly according to her own methods. If she knows, and can know, nothing from actual observation concerning the first beginnings of matter, of the cosmic nebula, or of life, it is quite otherwise with the history of living things since they first appeared, and with the phenomena of life as it exists and is propagated. Here are questions which are strictly scientific, forming the subject-matter of Palæontology and Biology, and these Sciences supplemented by others, such as Geology, Physical Geography, and Astronomy, furnish a mass of evidence bearing upon the subject of Organic Evolution. When therefore the great majority of men of Science, declare that the fact of genetic Transformism is established beyond the possibility of doubt, Evolutionists find themselves supplied with a plausible foothold on which to stand and rest their fulcrum, while, like Archimedes, they proceed to move the world.
That men of Science generally thus agree, cannot be questioned, and although this agreement is by no means so universal as is popularly supposed, there is no doubt that were the question to be settled by enumeration of the authorities on either side, Transformism would win easily. It may also be freely acknowledged, that Transformism in general and Darwinism in particular are theories to which on à priori grounds no exception need be taken, and that, so far at least as concerns their general scope,[{145}] apart from the origin of Man, no one can reasonably start with a prepossession against them. Nay, we will go farther, and say that to our way of thinking it appears immensely more probable, that things should always have gone on as they go on now, by the operation of the same natural laws, and that specific forms should have been naturally produced, as individuals of a species are produced now, by generation,—rather than that not only repeated acts of specific creation, but any operations totally different from those we witness, should have occurred to interrupt, and as we should judge, to mar, the Law of Continuity.
All this is true. But we are engaged on a scientific enquiry,—and if there be one principle more than another upon which Science insists, it is that we should prove all things, not by authority, but by evidence,—and that we should seek evidence, not in pre-conceived ideas as to what should be, but in observation of what is. Accordingly, while we are most ready to accept Transformism or Darwinism should we find solid reasons for doing so, we are bound, for the sake of Science, to demand unimpeachable proofs before subscribing to doctrines which are made responsible for so much.
Before proceeding farther it will be necessary to exhibit more in detail the exact character of the question we have to discuss.
According to the celebrated "Formula" of Mr. Herbert Spencer—"Evolution is an integration[{146}] of matter and concomitant dissipation of motion; during which the matter passes from a relatively indefinite, incoherent homogeneity, to a relatively definite, coherent heterogeneity; and during which the contained motion undergoes a parallel transformation." It would be interesting to know what idea this definition conveys to many of those who are in the habit of quoting it, but, so far as organic Evolution is concerned, it must mean that whereas in the earlier and lower forms of life one organ performed many different functions in an imperfect manner, evolutionary development has gradually produced higher forms, in which each function has its special organ, by which it is more perfectly discharged. As an extreme instance of the former condition, the Hydra has but two organs, an outside which respires, and an inside which digests. If it be turned inside out these functions are reversed; the skin becoming the stomach, and the stomach the skin. Thus Evolution has been an ascending process from the lower to the higher, from the less to the more organized.
Such, it must be added, has undoubtedly been the course of life. Amongst plants and animals alike, it began with lower and simpler forms, after which succeeded in due order others more developed and elaborately organized, the order in which they came upon the scene being much the same as that in which we should naturally arrange their specimens in a museum. Thus in the vegetable kingdom, first came such growths as sea-weeds and fungi, followed[{147}] by ferns and club-mosses,—yews and pines,—and so through grasses, canes, and palms, to the highest group in which are included our forest trees and the bulk of our garden flowers. In like manner, the animal series,—to mention only leading groups of which evidence is found,—starting with almost structureless Protozoa, followed by such forms as starfish and sponges, worms, molluscs and crustaceans, has advanced to vertebrate creatures—fishes, amphibians, reptiles, birds, mammals,—and finally to man.
Thus, in a quite intelligible sense, there has certainly been Evolution, or development,—that is to say, an orderly progression from lower types to higher, throughout the history of life on earth, from its commencement to the present time. But, this is not the point. Was such Evolution or development genetic? Was it wrought by descent with modification of form from form? That is what we have to enquire. If this has not been so, there has been no Evolution in the sense intended by Evolutionists.
According to their highest authority, Mr. Herbert Spencer, Evolution means "the production of all organic forms by the accumulation of modifications and of divergences by the addition of differences to differences."
Beyond all question [he adds] unlikenesses of structure gradually arise among the members of successive generations. We find that there is going on a[{148}] modifying process of the kind alleged as the source of specific differences, a process which, though slow, does, in time, produce changes—a process which to all appearance would produce in millions of years any amount of changes.[176]
The Transformist doctrine is, therefore, that one species of plants or animals, has in natural course grown out of another, through the aggregation of changes each exceedingly minute. Darwinism adds that the ruling principle of this process is Natural Selection. These are the points on which our enquiry turns, and we may conveniently commence with the second.[{149}]