182 THE PROBLEMS OF EVOLUTION 



wholly made up of accidents. The constancy and 

 uniformity of normal development in nature, re- 

 sults, as already noted, from the fact that a certain 

 degree of standardization has occurred in the course 

 of evolution as regards the range of such accidents 

 to which the developing individual is likely to be 

 exposed. This has been accomplished in various 

 ways, e,g,^ through position of the gonads, through 

 conditions under which fertilization occurs, through 

 the formation of enveloping membranes, jelly, or 

 capsules about the developing eggs, through the 

 selection of certain localities for ^gg deposition, 

 through care of the young, viviparity, etc. But 

 these various provisions do not eliminate external 

 factors; they merely tend to limit the variation in 

 range, in other words, to standardize their ac- 

 tion." ^ 



What is at the root of this self-determination.'^ 

 Here again we come near to the fundamental 

 interpretations of life, but within the limits of 

 sound biology the complexity of the problem is not 

 overwhelming. In spite of our ignorance of methods 

 of evolution we can only accept the view that the 

 intricacies of life are merely resultants of the in- 

 tricacies of heritage and environment interacting. 

 Existing life must owe its intricacy to gradual 

 evolution from a simpler primordium responding 

 to the vast and complex world environment 



^ Child, C. M., Physiological Foundations of Behavior, p. 222, 1924. 



