All figures after Castle 



PLATE IV. 



OVARIAN TRANSPLANTATION 



Fig. 1. A young, black guinea-pig lilte the one whose ovaries were transplanted into the 

 albino shown in Fig. 2. Fig. 2. An albino guinea-pig whose ovaries were replaced by 

 those from such a guinea-pig as that shown in Fig. 1. Fig. 3. An albino male guinea-pig 

 with which the one shown in Fig. 2 was mated. Figs. 4 and 5. Two of the six offspring 

 of the matings of the guinea-pigs shown in Figs. 2 and 3. All the otfspring were black. 



