My views spread slowly in England and America; and I am much surprised to find them most commonly accepted by geologists, next by botanists, and least by zoologists; . . . for the arguments from geology have always seemed strongest against me.
That the objection from the general absence of intermediate links between species was a pertinent one he acknowledged with characteristic candor.
Geology assuredly does not reveal any such finely graduated organic chain; and this is perhaps the most obvious and serious objection which can be urged against the theory.
He recognized that, so far as geological knowledge then went, whole groups of species sometimes seemed to make their appearance abruptly; though he argued that the increase of such knowledge had steadily tended to diminish this semblance of abruptness. Wholly eliminated these sharp transitions have never been, to this day; the latest authoritative expositor of the general results of paleontology says of d'Orbigny that, though "his ideas" were "too absolute, his observations remain none the less exact in their broad lines, and the sudden replacing of marine faunas, when passing from one stage to another, or even from zone to zone, must be considered almost a general rule." The same writer,[1] who is, of course, a convinced evolutionist, observes:
After all we can not forget that there exists an immense number of creatures without intermediate links, and that the relations of the great divisions of the animal or vegetable kingdom are much less strict than the theory demands. . . . The keenest partisan of the descent theory must admit that the fossil links between the classes and orders of the two kingdoms exist in infinitesimally small numbers.
The second argument of the paleontological opponents of the theory Darwin regarded as still more deserving of serious consideration.
The sudden manner in which several groups of species first appear in our European formations, the almost entire absence, as at present known, of formations rich in fossils beneath the Cambrian strata, are all undoubtedly of the most serious nature. The difficulty of assigning any good reason for the absence of vast piles of strata rich in fossils beneath the Cambrian system is very great. . . . The case at present must remain inexplicable, and may be truly urged as a valid argument against the views here entertained.[2]
To all these objections, as to that drawn from the absence of a uniformly progressive sequence in the superposition of species of certain classes, Darwin opposed a single reply: "the imperfection of the geological record"—an imperfection due not only to the inadequacy of geological exploration but to the inevitable absence of many chapters from the rock-history itself. Paleontology thus offered to neither side materials for a decisive proof of its case. Darwin's ninth chapter pre-
