INFLUENCE OF ENVIRONMENT 



351 



ova are in no wise changed by the foster 

 mother. They removed the ovary from a pure 

 black guinea-pig and put it in the place 

 of the ovary of a pure white animal. After 

 recovery from the operation this white female 

 with the "black" ovary was bred to a pure 



Fig. 80. Grafted frog embryos, anterior part, Rana syl- 

 vatica, posterior part, R. palustris. In later stages, and even 

 in the adult condition, the two parts preserve their peculiari- 

 ties. (From Harrison.) 



