Fig. 7. — A young, black guinea-pig, about three weelcs old. Ovaries taken 

 from an animal like this were transplanted into the albino shown immediately 

 below it. 



P'iG. 8. — An albino female guinea-pig. Its ovaries were removed and in 

 their place were introduced ovaries from a black guinea-pig, like the one shown 

 in Fig. 7. 



Fig. 9. — An albino male guinea-pig, with which was mated the albino shown 

 in Fig. S. 



