System, held up to the time of Newton, would have continued outstanding had Newton's generalization been disproved, so, were the theory of natural selection disproved, the theory of organic evolution would remain. Whether it were shown that natural selection is inoperative, or whether it were shown that though a partial cause it is inadequate to explain all the facts (the inheritance of functionally-wrought modifications being a co-operative cause); or whether it were shown that no cause hitherto alleged is adequate; the general doctrine that organisms of all kinds have arisen by the continual superposing of modifications upon modifications would maintain its place, though it would not be fortified so strongly. Lord Salisbury, however, in common with the immense majority of men, assumes that the hypothesis of organic evolution must stand or fall with its alleged causal agencies. Though in one paragraph he distinguishes between natural selection as an alleged agent, and the facts regarded as implying evolution which are said to be explained by it, yet, at the close of his address, he assumes the two to be so indissolubly connected that, if natural selection goes, evolution must go with it—that the facts are not naturally explicable at all, but must be regarded as supernatural. He says, referring to Prof. Weismann:—"I quite accept the Professor's dictum that if natural selection is rejected we have no resource but to fall back on the mediate or immediate agency of a principle of design." And thus he indorses the popular notion that Darwinism and Evolution are equivalent terms.
Though, speaking on behalf of biologists, who are conscious of the difference, Prof. Huxley, in seconding the vote of thanks, demurred to this identification, yet the above-quoted sentence reappears in the revised and republished form of Lord Salisbury's address.
Absence of direct proof of natural selection is duly emphasized by Lord Salisbury. He says:—"No man or succession of men have ever observed the whole process in any single case, and certainly no man has recorded the observation." And, as direct proof of the hypothesis is not forthcoming, it is tacitly assumed that we must accept the alternative hypothesis, which is equally without direct proof. Here I may be excused if, à propos of this position, I reproduce some passages from an essay published in pre-Darwinian days, when the development hypothesis, as it was then called, was universally ridiculed. The first part of the essay runs as follows:—
