cox, DARWIN AND THE MUTATION THEORY 451 



ment of the theory of natural selection was Mr. Darwin's most original and 

 greatest achievement. Time has proven that he could have afforded to 

 stand upon the general validity and applicability of this theory though every 

 step in his argument in its favor had needed review and modification; for 

 each passing year but adds to the impregnable mass of proofs by which it 

 is affirmed and supported. Properly regarded, the mutation theory does 

 not antagonize nor weaken the doctrine of natural selection — on the con- 

 trary it merely offers itself as a helpful substitute for, or adjunct to, one of 

 Darwin's subordinate steps in the approach to a consistent philosophy of 

 the origin of species, leaving the last great cause of evolution as efficient as 

 ever. It is, therefore, one of the tragedies of science that in this matter 

 Darwin should have been ready to surrender his main position rather than 

 to receive and to join forces with those who were coming to his aid, but 

 whom he failed to recognize as friends. 



