148 Heredity and Eugenics 



The white hen (W2), carrying an ovary from a black hen (B2) 

 mated to the black rooster, gave uniformly spotted chicks, i.e., white 

 chicks, with black spots on the dorsal surface of the head, neck, wings, 

 back, or on the tail. 



Owing to the uniform results from the controls, it may be assumed 

 that the strains of chickens used breed true to color. Therefore any 

 variations in the offspring of the operated hens were due to other 

 influences. 



The fact that in all cases of the operated hens white or black or 

 spotted fetuses or chicks were produced (i.e., the offspring showed 

 variations from the normal in color markings) shows : 



1. That the eggs from each of the operated hens were from the 

 transplanted ovary. Take hens B2 and W2. These hens were bred to 

 the roosters of their color. Had some portion of their own ovary not 

 been removed at the time of the operation (a remote possibility) and 

 was functioning, then we would have expected solid offspring like the 

 controls. But such was not the case. In the offspring from B3, in 

 which the male and foster mother were black, black predominated but 

 white occurred. This must have come through the white ovary. In 

 the offspring of W2, in which the male and foster mother were white, 

 white was the predominating color but black occurred. The black 

 therefore must have come from the black ovary. 



If we accept the statement that in ordinary crossing of black and 

 white breeds the white is dominant, then we assume that the same is 

 not true for this kind of (female) crossing, or that the original color 

 influence was more strongly preserved in the black than in the white 

 ovary. From the constancy in the results in the above two hens, we 

 may conclude that the ovaries transplanted into the other two hens, 

 B2 and W3, were the ones fimctioning during the laying season also. 



2. The foster mother exerted an influence on the color of the 

 offspring. Take hens B2 and W3. These hens were bred to the rooster 

 of the opposite color, i.e., the color of the transplanted ovary. Yet in 

 the former the majority, and in the latter all of the offspring were 

 spotted, i.e., white \vith black spots on the dorsal surfaces. In B2 the 

 male and ovary were white and the foster mother black; in W3 

 the male and ovary were black and the foster mother white. In both 

 cases white predommated in the offspring. It would seem, therefore. 



