40 T. H. MORGAN 



The expectation is that the black females shall be as numer- 

 ous as the sum of the two classes of males; there are about 600 

 too few males owing largely to a deficit in the brown class which 

 runs about 450 behind the black males. The analysis follows: 



Black 9 yBBiX — yBBrX 

 Brown d' ybBrX — ybBr 



^ , . .T. Black d' vBBrX — vbBrX 



Fi and gametes of F, ^^^^^ ^ ^^^^^^^ _ ^^^^^ 



Black 9 2 

 Fa Black a" 1 



Brown cf 1 



The reciprocal cross, brown females and black males gives 

 black females and brown males. The numerical data are as 

 follows : 



f Black 9 2191 



o ^ u T3 ^ /B 9 I Black cf 1987 



Br9byBc?= |g^. ^ = ^ grown 9 1532 



[ Brown cf 1448 



The expectation is equality throughout; but the Browns run, 

 class for class, about 600 behind the Blacks. The analysis 

 gives : 



Brown 9 ybBrX — ybBrX 9 

 Black d" yBBrX — ybBr d 



Fi 



Black 9 ybBrX — yBBrX 9 

 Brown cf ybBrX — ybBr d 



Brown 9 1 



Brown cf 1 



^- Black 9 1 



Black d 1 



Yellow by brown 



Yellow females by brown males give yellow females and 

 males. The numerical data are: 



