FIG. 10. A young, black guinea-pig, about three 

 weeks old. Ovaries taken from an animal like 

 this were transplanted into the albino shown 

 below. 



FIG. 11. An albino female guinea-pig. Its 

 ovaries were removed, and in their place were 

 introduced ovaries from a young, black guinea- 

 pig, like that one shown in Fig. 10. 



FIG. 12. An albino male guinea-pig, with which 

 was mated the albino shown in Fig. 11. 



