GERMINAL SELECTION. 33 



blocks that path. For the person who is convinced he 

 has found the right explanation is not going to seek 

 for it. 



I can understand perfectly well the hesitation that 

 has prevailed on this point in many minds, from their 

 having seen one aspect of the facts more distinctly than 

 the other. From this sceptical point of view Osborn 

 has drawn the following perfectly correct conclusion: 

 "If acquired variations are transmitted, there must be 

 some unknown principle in heredity; if they are not 

 transmitted, there must be some unknown factor in 

 evolution." 1 



Such in fact is the case and I shall attempt to point 

 out to you what this factor is. My inference is a very 

 simple one : if we are forced by the facts on all hands 

 to the assumption that the useful variations which 

 render selection possible are always present, then some 

 profound connection must exist betiveen the utility of 

 a variation and its actual appearance, or, in other 

 words, the direction of the variation of a part must be 

 determined by utility, and we shall have to see whether 

 facts exist that confirm our conjecture. 



The facts do indeed exist and lie before our very 

 eyes, despite their not having been recognised as such 

 before. All artificial selection practised by man rests 

 on the fact that by means of the selection of individuals 

 having a given character slightly more pronounced 

 than usual, there is gradually produced a general aug- 

 mentation of this character, which subsequently 

 reaches a point never before attained by any individual 



1 H. F. Osborn, "The Hereditary Mechanism and the Search 

 for the Unknown Factors of Evolution," in Biological Lec- 

 tures delivered at the Marine Biolog. Lab. at Wood's Holl 

 in the Summer Session of 1894. Boston, 1895. 



