DARWINISM'S PRESENT STANDING. 377 



and change, instituted by this agent of beginnings, natural 

 selection will choose those to persist by saying No to those 

 that may not. And the result is organic evolution. 



But all this is equivalent to saying that there are other 



important factors in descent than selection, and that as to 



the beginnings of descent and this is species- 



The causes of . 



variation and the forming these other factors are the more im- 

 meansofsegre- portan t ones. Which I believe is true. The 



gation, the chief 



factors in spe- causes of variation and the means of segrega- 

 cies- orming, ^ Qn Qr j so i a ^ on are ^ e c hief factors in actual 



species-forming. Certainly the mutations theory is not yet 

 ready to offer itself as an explanation of adaptation, how- 

 ever confidently it may claim to be enrolled among species- 

 forming factors. The very same objections that have served 

 to topple down selection from its high seat of honour, can be 

 directed immediately and effectively against this latest claim- 

 ant for recognition as the Great Cause of descent. Nor can 

 geographical isolation explain modification where adaptation 

 is included. Nor can Lamarck's beautiful explanation of 

 adaptation claim validity, until the actuality of its funda- 

 mental postulate, the carrying over of ontogenic acquire- 

 ments into phylogeny, be proved. And so with Buffon and 

 St. Hilaire's influence of the ambient medium, and Eimer's 

 modifying factors. Nor can any Nagelian automatic per- 

 fecting principle hold our suffrage for a moment unless we 

 stand with theologists on the insecure basis of teleology. 



No, let no ambitious student hesitate to take up the 



search for the truth about evolution from the notion that 



, biology is a read book. The ''Origin of Spe- 



The unknown 



factors of evoln- cies" was the first opening of the book that 

 the world recognised at least ; poor Lamarck 

 opened the book but could not make the world read in it 

 and that time when it shall be closed because read through 

 is too far away even to speculate about. With Osborn 4 let 

 us join the believers in the "unknown factors in evolution." 



