82 CREATIVE EVOLUTION CHAP. 



strengthened and grow by exercise, nobody will deny. 

 But it is a long way from that to the progressive de 

 velopment of an eye like that of the molluscs and of 

 the vertebrates. If this development be ascribed to 

 the influence of light, long continued but passively 

 received, we fall back on the theory we have just 

 criticized. If, on the other hand, an internal activity is 

 appealed to, then it must be something quite different 

 from what we usually call an effort, for never has an 

 effort been known to produce the slightest complication 

 of an organ, and yet an enormous number of complica 

 tions, all admirably coordinated, have been necessary 

 to pass from the pigment-spot of the Infusorian to the 

 eye of the vertebrate. But, even if we accept this 

 notion of the evolutionary process in the case of 

 animals, how can we apply it to plants ? Here, 

 variations of form do not seem to imply, nor always 

 to lead to, functional changes ; and even if the cause 

 of the variation is of a psychological nature, we can 

 hardly call it an effort, unless we give a very unusual 

 extension to the meaning of the word. The truth is, 

 it is necessary to dig beneath the effort itself and look 

 for a deeper cause. 



This is especially necessary, we believe, if we wish to 

 get at a cause of regular hereditary variations. We are 

 not going to enter here into the controversies over the 

 transmissibility of acquired characters ; still less do we 

 wish to take too definite a side on this question, which is 

 not within our province. But we cannot remain com 

 pletely indifferent to it. Nowhere is it clearer that 

 philosophers cannot to-day content themselves with 

 vague generalities, but must follow the scientists in 

 experimental detail and discuss the results with them. 

 If Spencer had begun by putting to himself the question 



