FIG.IO. 



^^e"- 





FIG.12. 



Fig. 10. — A j-oung, l^lack 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 tlieir plaee were 

 introduced ovarie.s 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. 



