HEREDITY OF BODY COLOR IN DROSOPHILA 



39 



F2 generation are as follows. The counts of the Fi flies are taken 

 from another similar cross. 



Br 9 by G cf = 



Owing to the failure of many of the brown females to breed 

 the numerical results are small. The expectation for the females 

 is gray 3, black 1, yellow 3, brown 1, and for the males, gray 3, 

 black 1, yellow 3, brown 1. It will be observed that the gray 

 females greatly exceed the yellow females while the yellow males 

 exceed slightly the gray males. The Fi females are gray and 

 the males yellow. ^ The analysis follows: 



Black by brown 



When black females are mated to brown males all the off- 

 spring are black. The numerical data for Fi and F2 are as fol- 

 lows: 



B 9 by Br cf = ^ ^^ ;-;^ = Black d 3015 



[U o -/4 ^ Brown d 2472 



1 In another experiment the gray males equalled the gray females. 



