COUPLING 



93 



If it be sound, then the constitutions of males and 

 females in barred and unbarred breeds which breed 

 true should be : 



Barred 



Unbarred 



Males 



MM 

 BB 



Females 



M 

 B 



F 



b 



Males 



MM 

 bb 



Females 



M 



b 



F 

 b 



and barred males with unbarred females should produce 

 equal numbers of males and females, and both sexes 

 should be barred. 



MM , M 



BB ^''^ b 



F 



b 



should produce 



MM 



Bb 



and 



M 

 B 



F 



b 



for the males must take B from their sires and the free 

 factor b from their dams, while the females must take 

 B from their sires and the coupled factor b from their 

 dams. Dr. Raymond Pearl crossed Barred Plymouth 

 Rock cocks with Cornish Indian Game hens, which are 

 black and unbarred, and their adult progeny consisted 

 of 60 cocks and 68 hens, all barred. 



On the other hand, the reverse cross, unbarred cocks 

 with barred hens, should again produce equal numbers 

 of males and females, but, while all the males should 

 be barred, the females should all })e unbarred. 



MM , M 



b b '^'^^ B 



F 



b 



, ., , MM - M 



should produce ,^ , and , 



F 

 b 



