ORGANIC SELECTION 279 



a function in the mechanism of the body. Natural 

 selection favours this strengthening and the two vari- 

 ations continue to develop in parallel directions. 



In the case of complex instincts a simultaneous and 

 accurate adaptation cannot very well be accounted for 

 by natural selection alone ; for ontogenetic adaptation 

 develops many special instincts which, taken sepa- 

 rately, would serve no useful purpose. 



There is also another factor which gives acquired 

 instincts the appearance of being hereditary : the train- 

 ing of the young by the parents. Whatever one gen- 

 eration acquires through ontogenetic adaptation is 

 transmitted to the next generation which progresses 

 and develops within the limits and following the ex- 

 ample set by the first generation. Thus the results 

 of organic selection create the illusion of a direct 

 hereditary transmission. Baldwin designates this 

 type of heredity as "social heredity." 



The theory of organic selection explains why vari- 

 ations may succeed each other in a determined direc- 

 tion. The determining factor, according to Bald- 

 win, is not the germinal variations but the action ex- 

 erted on them by acquired modifications. In this 

 respect Baldwin's theory bears a certain likeness to the 

 orthogenetic theories based on germinal variations 

 (like Osborn's theory of organic selection), and in 

 order to avoid confusion, Baldwin designates this de- 

 termined evolution by the name of orthoplasis. 



