THE ORGANIC TENDENCY 195 



mental adaptation, while others are held back. The 

 creative brain, the tool-making hand, the fleet 

 hind limb of man apparently combine in acceler- 

 ated adaptation, while forest-loving primates ad- 

 vance much more slowly." ^ But can this be 

 true? If a certain part undergoes great develop- 

 ment in one line of descent it must be due to causes 

 in heritage or environment. If glands are involved, 

 they cannot progress without adequate heritage 

 and favorable environmental conditions, and if 

 they result in true evolution their effect on the 

 heritage must certainly be as an internal environ- 

 mental influence. Moreover no character can long 

 remain "independent of selection, of environment, 

 of habit," certainly not long enough to be involved 

 in phylogeny, for it must soon influence the oppor- 

 tunities of the individuals possessing it, either as 

 a hindrance to normal activity, as an aid under 

 normal conditions of life, or as a factor in bringing 

 about a change in the internal environmental 

 conditions. Some of these relations must develop 

 unless the character is to remain indifferent in 

 individual existence and in evolution alike. 



The fact remains that organisms of the present 

 have gone far along the path of self-determination. 

 As we have already noted, the complex body re- 

 duces the effect of environmental fluctuations to 

 a minimum through the ability of each associated 



6 Osborn, H. F., Science N. S., Vol. LXXI, p. 7, 1930. 



