76 HEREDITY AND ENVIRONMENT 



sociation tracts may cause permanent loss of 

 consciousness. 



The development of all of these psychical 

 faculties runs parallel with the development 

 of bodily structures and apparently the 

 method of development in the two cases is 

 similar, viz., progressive differentiation of 

 complex and specialized structures and func- 

 tions from relatively simple and generalized 

 ^beginnings. Indeed the entire organism, 

 structure and function, body and mind, is a 

 unity, and the only justification for dealing 

 with these constituents of the organism as if 

 they were separate entities, whether they be 

 regarded in their adult condition or in the 

 course of their development, is to be found in 

 the increased convenience and effectiveness of 

 such separate treatment. 



Development, like many other vital phe- 

 nomena, may be considered from several dif- 

 ferent points of view, such as (1) physico- 

 chemical events involved, (2) physiological 

 processes, (3) morphological characters, (4) 

 ecological correlations and adaptations, (5) 

 psychological phenomena, (6) social and 



