86 HEREDITY AND ENVIRONMENT 



functions. Just as the character of any func- 

 tion is determined by the organism, though it 

 may be modified by environment, so the char- 

 acter of development is determined by hered- 

 ity, i. e., by the organization of the germ cells, 

 though the course and results of develop- 

 ment may be modified by environmental 

 conditions. 



Summary 

 In conclusion, we have briefly reviewed in 

 this lecture the well known fact that every liv- 

 ing thing in the world has come into existence 

 by a process of development; that the entire 

 human personality, mind as well as body, has 

 thus arisen; and that the factors of develop- 

 ment may be classified as intrinsic in the or- 

 ganization of the germ cells, and extrinsic as 

 represented in environmental forces and con- 

 ditions. The intrinsic factors are those which 

 are commonly called heredity, and they direct 

 and guide development in the main; the ex- 

 trinsic or environmental factors furnish the 

 conditions in which development takes place 

 and modify, more or less, its course. 



