296 THE POPULAR SCIENCE MONTHLY. 



hind-foot. 1 la still older forms the series of the dibits will be more 

 and more complete, until we come to the five-toed animals, in which 

 most assuredly the whole series took its origin. 



That is what I mean, ladies and gentlemen, by demonstrative evi- 

 dence of evolution. An inductive hypothesis is said to be demon- 

 strated when the facts are shown to be in entire accordance with it. 

 If that is not scientific proof, there are no inductive conclusions which 

 can be said to be scientific. And the doctrine of evolution at the 

 present time rests upon exactly as secure a foundation as the Coper- 

 nican theory of the motions of the heavenly bodies. Its basis is pre- 

 cisely of the same character the coincidence of the observed facts 

 with theoretical requirements. As I mentioned just now, the only 

 way of escape, if it be a way of escape, from the conclusions which I 

 have just indicated, is the supposition that all these different forms 

 have been created separately at separate epochs of time, and I repeat 

 that of such an hypothesis as this there neither is nor can be any sci- 

 entific evidence, and assuredly, so far as I know, there is none which 

 is supported, or pretends to be supported, by evidence or authority 

 of any other kind. I can but think that the time will come when 

 such suggestions as these, such obvious attempts to escape the force 

 of demonstration, will be put upon the same footing as the supposi- 

 tion made by some writers, who are, I believe, not completely extinct 

 at present, that fossils are not real existences, are no indications of 

 the existence of the animals to which they seem to belong ; but that 

 they are either sports of Nature or special creations, intended as I 

 heard suggested the other day to test our faith. In fact, the whole 

 evidence is in favor of evolution, and there is none against it. And I 

 say this, although perfectly well aware of the seeming difficulties which 

 have been adduced from what appeal's to the uninformed to be a scien- 

 tific foundation. I meet constantly with the argument that this doc- 

 trine of evolution cannot be correct, because it requires the Lapse of a 

 very vast period of time, and that the duration of life upon the earth 

 thus implied is inconsistent with the conclusions arrived at by the as- 

 tronomer and the physicist. I may venture to say that I am familiar 

 with those conclusions, inasmuch as some years ago, when President 

 of the Geological Society of London, I took the liberty of criticising 

 them, and of showing in what respects, as it appeared to me, they 

 lacked complete and thorough demonstration. But, putting that 

 point aside altogether, suppose that, as the astronomers, or some of 

 them, and some physical philosophers, tell us, it is impossible that 

 life could have endured upon the earth for as long a period as is re- 

 quired by the doctrine of evolution- supposing that to be proved, 

 what I want to know is, what is the foundation for the statement that 



1 Since this lecture was delivered, Prof. Marsh has discovered in the lowest Eocene 

 deposits of the West a new genus of equine mammals (Eohippits), which corresponds 

 very nearly to this description. American Journal of Science, November, 1876. 



