360 HEREDITY AND ENVIRONMENT 



stimuli acting upon germ cells at an early 

 stage in their development may rarely cause 

 changes in their hereditary constitution, but 

 changes produced in somatic cells do not 

 cause corresponding changes in the hereditary 

 constitution of the germ cells. (3) Germ cells 

 like somatic cells may undergo modifications 

 which are not hereditary ; they may be stained 

 with fat stains and the generation to which 

 they give rise be similarly stained; they may 

 be poisoned with alcohol or modified by tem- 

 perature and such influence be carried over to 

 the next generation without becoming heredi- 

 tary. All such cases are known as "induction" 

 and many instances of the supposed inheri- 

 tance of acquired characters come under this 

 category. 



