HEREDITY OF BODY COLOR IN DROSOPHILA 41 



f Yellow 9 2295 



Y9byBrcf= (^ ? 115 ^ J Yellow c? 2232 



xvuyma \Ya^99 | Brown? 830 



Brown cf 758 



The expectation is three yellows to one brown, and the num- 

 bers approximate to this relation. When the difficulties of 

 separating these two classes is taken into account the agree- 

 ment is remarkably close. The analysis follows: 



Yellow 9 YbBrX — YbBrX 

 Brown d^ ybBrX — ybBr 



Yellow 9 YbBrX — ybBrX 9 

 ^' Yellow d" YbBrX — ybBrX — ybBr — YbBr 



Yellow 9 3 

 p Yellow cf 3 



Brown 9 1 

 Brown d^ 1 



The reciprocal cross, brown females by yellow males, gives 

 yellow females and males. The numerical data are: 



[ Yellow 9 .....1181 



u n u V ^ /Y 9 129 I Yellow cf 1409 



Br9byYcf= |y 0^102= Brown 9 571 



[ Brown cf 520 



The expectation is again three yellows to one brown; and this 

 is fairly well realized. There are more yellow males than yellow 

 females, and slightly more brown females than brown males. 

 The analysis is as follows: 



Brown 9 ybBrX — ybBrX 

 Yellow d" YbBrX — YbBr 



Yellow 9 ybBrX— YbBrX 

 ' Yellow cT ybBrX— YbBrX — YbBr — ybBr 



Yellow 9 3 



Yellow (f 3 



^ - Brown 9 1 



Brown cf 1 



