38 T. H. MORGAN 



Wild (gray) by brown 



When the normal (Gray) females were mated with brown 

 males all the offspring were gray. The numerical results for 

 Fi and Fo were as follows: 



Gray 9 2618 



Gray d" 1342 



Black 9 765 



Black cf 351 



Yellow d' 985 



Brown cf 300 



r^ r. u T> ^ , G 9 266 

 G9byBrc:?= ^ G cf 236 



The expectation is six gray females to two black females, and 

 for the males 3 gray, 3 yellow, one black, one brown. The normal 

 females are almost exactly twice the number of normal males. 

 The normal males exceed three times the black males by nearly 

 300; and the black males exceed the brown males 50 flies. The 

 yellow males are somewhat more than three times as numerous 

 as the brown males, but less ihaji three times as numerous as the 

 black males. The yellow males, which should be as numerous 

 as the normal males are about 350 fewer. The sum total of 

 all the females is 3383 and of the males 2988. The males are 

 about 400 flies fewer Ihan the females. 



Despite these differences the numbers accord fairly well with 

 the expectation, at least the classes stand in the same general 

 relation that the analysis calls for. The analysis follows: 



Gray 9 YBBrX— YBBrX 

 Brown d' ybBrX — ybBr 



Fi 



Gray 9 YBBrX — ybBrX 

 Gray d" YBBrX — ybBrX 



Gametes of Fi 



vBBrX — YBBrX — ybBrX — YbBrX 9 

 yBBrX — YBBrX — ybBr — YbBr d 



The reciprocal cross, brown females by gray males gave gray 

 females and yellow males. The numerical data for the Fi and 



