HEREDITY OF BODY COLOR IN DROSOPHILA 



37 



The reciprocal cross yellow females by black males gives 

 gray females and yellow males. The numerical data follow: 



Y ? by B c^ = 



/G 9 

 lYc? 



f Gray 



I Gray 



I Black 



j Black 

 Yellow 



Yellow d" 1548 



Brown 9 441 



Brown cf 428 



.2442 

 .1893 

 .1893 

 , 723 

 .1547 



The expectation for the females and males alike is gray 3, 

 yellow 3, black 1, brown 1. There are about 900 more gray 

 females than yellow females; while the gray males are only 350 

 more numerous than the yellow males. The gray females and 

 yellow males are the Fi classes. The yellow females are as 

 numerous as the yellow males. The black males are about 

 a third of the gray males and more than this ratio in regard 

 to the yellow males. The blacks run well ahead of the browns, 

 the females being more than four times as numerous. The analysis 

 is as follows: 



Yellow 9 bYBrX— j^j^©!^ 

 Black d" ByBrX — byBr 



F: 



Gray 9 byBrX — ByBrX 

 Yellow d" bYBrX — byBr 



Gametes of Fi 



byBrX — bYBrX 

 byBrX — bYBrX 



ByBrX — BYBrX 9 

 byBr — bYBr d" 



Brown 9 1 Brown cf 1 



Yellow 9 3 Yellow cf 3 



Black 9 1 Black d' 1 



Gray 9 3 Gray d' 3 



