Ontogenic Agencies 93 



ogy) by Bernheim, Janet ; (in children) among others by 

 the present writer (in Mental Development^ Chap. IX., 

 with citations ; see also Orr, Theory of Development^ 

 Chap. IV.). These changes I propose to call ' neuro- 

 genetic,' laying emphasis on what is called by Romanes, 

 LI. Morgan, and others the ' selective property ' of the 

 nervous system, and of life generally. 



Third, there is the great and remarkable series of ac- 

 commodations secured by conscious agency, which we may 

 throw together as 'psycho-genetic' The processes involved 

 here are all classed broadly under the term * intelligent,* 

 e.g., imitation, gregarious habits, parental instruction, the 

 lessons of pleasure and pain and of experience generally, 

 reasoning from means to ends, etc. 



We reach, therefore, the following scheme : — 



Ontogenetic Modifications Ontogenic Agencies 



1. Physico-genetic i. Mechanical. 



2. Neuro-genetic 2. Nervous. 



3. Psycho-genetic 3. Intelligent. 



Pleasure and pain. 

 Imitation. 



Higher mental processes. 

 (Association of Ideas, 

 etc.) 



Now it is evident that there are two very distinct ques- 

 tions which come up as soon as we admit modifications 

 of function and of structure in ontogenetic development ; 

 especially if these are considered with reference to the 

 larger problem of evolution. 



First, there is the question as to how these modifications 

 can become adaptive in the life of the individual creature ; 



