INFLUENCE OF ENVIRONMENT 337 



mental conditions it is probable that heredity, 

 which is the constant factor in this case, is also 

 the determining factor for that character. On 

 the other hand if a character develops in re- 

 sponse to peculiar stimuli and does not appear 

 in other individuals of the same genotype in 

 which such stimuli are lacking it is said to be 

 an environmental or acquired character. 



But though environment and functional ac- 

 tivity exercise a great influence on the course 

 of development there is no sufficient evidence 

 that they produce corresponding changes in 

 heredity. Hereditary constitution is not gen- 

 erally changed by accidents of environment, 

 but individual development is so changed. 



Briefly stated the question of the inheritance 

 of acquired characters is this: Can peculiari- 

 ties of the environment which bring about the 

 development of somatic characters so affect the 

 germ cells that they will produce these so- 

 matic characters in the absence of the peculiar 

 environment? Can the characteristics of a de- 

 veloped organism enter into its germ cells and 

 be born again in the next generation? Con- 

 sidering the fact that germ cells are cells and 



