THE ORGANIC TENDENCY 197 



nance of effective environmental contacts. Because 

 the latter is much more elaborate it is able to effect 

 much finer details of adjustment, even involving 

 modification of the environment itself, but again, 

 it does so within its inherent latitude of possibility. 

 Even intelligence is not omnipotent. It has enabled 

 man to accomplish an unsurpassed invasion of the 

 earth, but it is not able to decree that he shall 

 enter a difficult environment and become accli- 

 mated to it; he enters it through his ability to 

 produce artificially the conditions necessary for 

 his existence. He may be forced even under these 

 tolerable conditions to live abnormally in some 

 respects. The functions of his body may shift 

 within their inherent limits to meet conditions 

 beyond his control, and in shifting they must in- 

 evitably provide a changed internal environment 

 which may play a part in the future development 

 of his body and its derivatives. But intelligence 

 can accomplish no more in evolution than this 

 deliberate exposure to conditions which may result 

 in evolution. 



Because adjustment is the price of existence, it 

 is impossible to imagine an environmental condi- 

 tion so extreme as to demand an absolute change 

 of vital functions and yet within the range of 

 tolerance of the organism. A certain latitude must 

 characterize all vital processes; they can scarcely 

 be rigidly uniform. Obviously conditions of life 



