INFLUENCE OF ENVIRONMENT 353 



white male (Fig. 81). Three litters of off- 

 spring from these parents were all pure black 

 as shown in Figure 82. Although both parents 

 were pure white all the offspring of the Fi 

 generation were black because they came from 

 "black" eggs and black is dominant over white. 

 The fact that these "black" eggs developed in 

 the body of a white female did not in the least 

 change their hereditary constitution. 



A still more intimate union takes place when 

 the dominant and recessive characters come 

 together in any zygote. These characters, or 

 rather the factors which determine them, may 

 be intimately associated in every cell of the 

 organism throughout an entire generation and 

 yet we may get a clean separation of these 

 characters in the next generation; in many 

 cases neither the dominant nor the recessive 

 character has been at all modified by its most 

 intimate association with the other. 



Above, young black female; in the middle, mature white fe- 

 male; below, mature white male. The white female's ovary 

 was removed and in its place was put the ovary from the 

 black female. The white female (with "black" ovary) was 

 then bred to the white male. (From Castle.) 



