The Scientific Evidences of Organic Evolution | Page 9

rudiment is present. But the vacillating policy in the matter of rudiments does not end here; for it is shown, if possible, in a more aggravated form where, within the limits of the same natural group of organisms, a rudiment is sometimes present and sometimes absent. For instance, to take again the case of limbs, in nearly all the numerous species of snakes there are no vestiges of limbs at all; but in the python we find beneath the skin very tiny rudiments of the hind limbs. Now, is it a worthy conception of Deity that, while neglecting to maintain His unity of ideal in the case of nearly all the numerous species of snakes, He should have added a tiny rudiment in the case of the python, and even in that case should have maintained His ideal type very inefficiently, inasmuch as only two limbs instead of four are represented? Or, again, take the case of the limb in other animals. Five toes seem to constitute the ideal type, notwithstanding that in numberless cases this ideal fails in its structural expression. Now, in the case of the horse, one toe appears to have become developed at the expense of the others; for the so-called knee of the horse is really the wrist or ankle, and the so-called shank the middle toe or finger very much enlarged. But on each side of this enlarged toe there are, beneath the skin, rudimentary bones of two other toes--the so-called splint-bones. So far good, but three toes are not five; so special creationists must suppose that while in this case the Deity has, so to speak, struggled to maintain the uniformity of His ideal, His efforts have nevertheless conspicuously failed. How much less strained is the scientific interpretation; for I may mention that in this particular case, besides the general inference that rudiments point us to a remote ancestry, we have direct pal?ontological evidence that there have been a whole series of extinct horse-like animals, that began low down in the geological strata with five toes (on the fore-feet, one being rudimentary), which afterwards became reduced to four and then to three; after which the two lateral toes began to become rudimentary, as we now see them in oxen, and later on still more so. Lastly, as we come nearer to recent times, we find fossils of the existing horse, with the lateral toes shortened up to the condition of splint-bones. Thus we have some half-dozen different genera of horse, all standing in a linear series in time as in structure, between the earliest representative with the typical number of five toes, and the existing very aberrant form with only one toe.
It is sometimes said that a striking corroboration of a scientific theory is furnished when it enables us correctly to predict discoveries. Such a corroboration is afforded in this instance; for Professor Huxley, speaking in 1870, said, "If the expectation raised by the splints of the horses that, in some ancestor of the horses, these splints would be found to be complete digits, has been verified, we are furnished with very strong reasons for looking for a no less complete verification that the three-toed plagiolophus-like 'avus' of the horse must have had a five-toed 'atavus' at some earlier period. No such five-toed 'atavus,' however, has yet made its appearance." But since then the "atavus" has made its appearance, if not with five complete toes, at least with four complete and one rudimentary; and any day we may hear that Professor Marsh has found in still earlier strata a more primitive form with all five toes complete.
I have no space to go into the evidence of similar "missing links" which have been recently supplied by pal?ontological researches in the case of several other groups of animals; but their consideration seems to me quite to justify a more recent utterance of Professor Huxley, who, in 1878, wrote in the Encyclop?dia Britannica: "On the evidence of pal?ontology, the evolution of many existing forms of animal life from their predecessors is no longer an hypothesis, but an historical fact; it is only the nature of the physiological factors to which that evolution is due which is still open to discussion."

III.
THE ARGUMENT FROM GEOLOGY.
But this allusion to fossils leads me to the next division of my subject--the argument from geology. It is not, however, necessary to say much on this head, for the simple reason that the whole body of geological evidence is for the most part of one kind, which although of a very massive, is of a very simple character. That is to say, apart from the increasingly numerous cases, such as the one just mentioned, which geology supplies of extinct "intermediate links" between particular species now living, the great weight of the geological evidence