which involves all negative evidence, might have prevented a generation of logical inconsequence in the discussion of man's origin. The fact that no so-called connecting links have been found can have no value whatever as evidence until it is shown that the whole earth has been searched and that there are none, and that no such fossils have ever been destroyed by natural processes. The deduction is justified by the evidence from other departments.
Agassiz, I believe, made the promise to furnish the positive evidence that no such fossils ever existed by showing that the geological series, at least so far as man is concerned, is complete; and hence that if they ever existed they should have been found. Death interfered with the fulfillment of the promise. He, like others, believed that man appeared at some definite place at some definite time in the world's history. Had he succeeded in proving the geological series complete, he would have caught, not others, but himself, in his logical toils. He first of all men would have been under obligation to show when and where man did appear, and that connecting links were not among the circumstances that immediately preceded his appearance.
The radical disappearance of objections to the theory before the introduction of new and especially the pertinacity of the old evidence is extremely interesting. There are imperfections in the evidence, many of which can never be removed. But the difficulties are not logical but practical; they are due to scientific ignorance. In every phase of its development the theory has fulfilled the conditions imposed upon it by logic, and repeated the history of other established scientific doctrines. At first superficial and catastrophic, but approaching through formality to Nature's path, biological science finally entered upon an explanation of its natural arrangements and formal laws. The theory of evolution itself passed from the condition of a simple induction to the explanation of vast numbers of facts that had been empirically discovered; opened new fields of investigation; led to the discovery of whole series of phenomena that had been previously overlooked; and gave rise to confident expectation frequently culminating in definite predictions subsequently verified by investigation—until, in the words of perhaps the foremost investigator in America, "we are in fact doing hardly anything else to-day than to verify the suggestions which evolution makes."