CHAPTER XI 

 SPENCER 



ONE of the most noteworthy attempts to construct an 

 adequate theory of fertility and population was the hypo- 

 thesis put forward by Herbert Spencer to the effect that 

 the degree of fertility varies inversely with the cost of 

 individuation. It cannot, however, be accepted as an 

 adequate expression of the facts. In the first place, 

 Spencer made no distinction between the variation in 

 the inherited potential degree of fertility as between 

 species and species and the variation in the actual degree 

 of fertility of given individuals under the direct influence 

 of the environment. This is an omission of the same 

 magnitude as if he had discussed organic variation in 

 general without distinguishing between the inherited 

 potentialities of the organism and their reaction to the 

 influences of the environment. 



Spencer covers both questions with the same formula, 

 and this renders the argument confused from the outset, 

 as the two questions are wholly distinct. Under no 

 circumstances could the fertility of a horse equal the 

 normal fertility of a rabbit. The potential fertility of 

 each species will be adjusted to its needs during the 

 evolution of the type and handed down by heredity. 

 The variation of the actual degree of fertility will be 

 decided by the direct action of the environment. 



Spencer also put forward his theory as an explanation 

 of both sexual and asexual genesis. He quotes the case 



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