ON POPPIES 



Moreover, if the factors for chocolate are 

 absent, the factors for grayness and blackness may 

 neutralize each other, and exist in what is called 

 a masked condition, neither one being able to 

 make itself manifest on account of the presence 

 of the other, because both are dominant factors; 

 so that the mouse will be white, yet will carry the 

 factors for grayness and for blackness masked in 

 its germ plasm. 



When the chocolate factors are present, how- 

 ever, in addition to the factors for blackness and 

 grayness, the presence of three dominant color 

 factors has the curious effect of enabling one of 

 them, in this case gray, to make itself manifest. 



So the chocolate factor is necessary to produce 

 a gray mouse; and the chocolate colored mouse 

 will appear only when the factors for grayness 

 and blackness are absent. 



This rivalry of dominant color factors, with 

 subordination of one to another, even though both 

 are dominant over whiteness, has previously been 

 briefly referred to, and it has been noted that, for 

 convenience in describing the condition, biologists 

 have come to speak of a factor that thus subordi- 

 nates another, in the sense in which gray subordi- 

 nates black in the coat of the mouse, as epistatic; 

 the subordinated color factor (in this case black) 

 being said to be hypostatic. 



[129] 



