140 THE PROBLEMS OF EVOLUTION 



recognized possibility of a chemical association be- 

 tween the body and the germinal tissues, which 

 may impress individual responses on the heritage 

 in some degree. 



One of the most unfortunate of all tendencies 

 growing out of opposition to the Lamarckian view 

 of evolution is the evasive theory of parallel in- 

 duction, the idea that an environmental stimulus 

 may bring about a certain response in the body 

 of an organism and at the same time act directly 

 upon its germ plasm to produce a determiner for 

 the hereditary transmission of the character. If 

 such a peculiar association of factors were neces- 

 sary, it would be as satisfactory a solution of the 

 difficulty as any, for the desired end is not the 

 establishment of any one theory but only the dis- 

 covery of the facts. It can make no difference in 

 results if the adjustment of species to the environ- 

 ment is effected by direct action of the environment 

 on the germ plasm or by indirect action through 

 the body. But germ cells and somatic cells are not 

 the same. It is difficult to see how the same en- 

 vironmental influence, acting on somatic cells in 

 one case and on germ cells in the other, could in 

 one produce a given adaptation and in the other a 

 determiner which would later produce the same 

 adaptation without the intervention of the en- 

 vironmental stimulus. Such a situation would be 

 much more difficult to understand than the simple 



