306 HEREDITY AND ENVIRONMENT 



of heredity. The modifications which may be 

 produced by environment and education are 

 small and temporary as compared with those 

 which are determined by heredity. 



3. These conclusions are, in the main, well 

 founded. The evidence of the tremendous im- 

 portance of heredity is so complete that we 

 may rest assured that thinking men will never 

 again return to the position which prevailed 

 until a few years ago regarding the all-impor- 

 tance of environment. And yet there is danger 

 of going too far in the opposite direction. 

 Neither environment nor heredity is all-im- 

 portant, but both are necessary to develop- 

 ment. The germ cells with all their inherent 

 possibilities would forever remain germ cells 

 were it not for environmental stimuli. The 

 realization of germinal possibilities is depend- 

 ent upon the responses of the germ to en- 

 vironmental stimuli, and although heredity is 

 a relatively constant factor while environment 

 is a more variable one, nevertheless the two 

 are indispensable to development. Only by 

 experiment can the relative importance of 

 heredity and environment in development be 



