GENETIC STUDIES ON FLOUR-MOTH 



431 



Among these 370 moths there are recorded 218 sooty, 78 type, 

 17 sooty black, and 57 black. There are 296 gray to 74 black, 

 showing slight deficiency of black, the expectation being 277.5 

 to 92.5. Among the gray the proportion, 218 sooty to 78 type, 

 is .very close to expectation, 222 to 74. Among the black how- 

 ever, the ratio is reversed, there being 17 sooty black to 57 black. 

 Apparently black reverses the dominance of sooty. On the 

 basis of this reversal the expectation is 18.5 to 55.5, very close 

 to the numbers actually obtained. Certain black moths have 

 the sooty base appearing as a 'ghost pattern.' This is the hetero- 

 zygous condition, sS. The moth shown in figure o is of this 

 character. It is impossible to separate these from other blacks 

 with any accuracy, but easy to distinguish the homozygote, SS, 

 since the factor S not only blackens the base and outer margins 

 of the wings, but also suppresses pigment in the intermediate 

 area. In the duplex condition of the factor this supression is 

 strong enough to affect the black pigment of the bb moth, as in 

 figure p. 



A sooty black male of this type, SS.bb, was paired (127) with 

 a type female, ss.BB. There were produced 190 sooty, 80 males 

 and 110 females. Cultures were made from these sooty as 

 shown in table 2. 



TABLE 2 



