THE ORGANIC TENDENCY 179 



the most striking point of emphasis upon the en- 

 vironment as a factor in evolution, for it leaves us 

 no alternative to the acceptance of the environ- 

 ment as the primary reality and the primordial 

 living substance as the result of a favorable juxta- 

 position of materials under a peculiar complex of 

 conditions. In the recognition of a certain degree 

 of self-determination as essential to the preserva- 

 tion of living things from the destructive forces of 

 a fluctuating environment we have the beginning 

 of heritage. To say that heritage has been respon- 

 sible for all evolution is a denial of its probable 

 origin. To say that it is now the source of all 

 evolutionary change in living things is a recogni- 

 tion of the control which it has wrested from the 

 environment, the degree of self -adjustment which 

 it has attained, but at the same time this attitude 

 is a failure to give due recognition to the part 

 which the environment continues to play. While 

 there is the slightest residuum of dependence upon 

 the environment, and this must always be, environ- 

 ment is a factor which must be considered in all 

 organic phenomena. 



The past evolution of living things presents a 

 series of phenomena which are strongly suggestive 

 of pure opportunism. In the origin of life, at the 

 outset, our hypotheses leave us only the one logical 

 explanation which has just been mentioned. As we 

 ascend the scale of known phylogenetic series a 



