rs 



THEORY OF EVOLUTION 



In the reciprocal cross (fig. 40) black cock 

 by barred hen, the daughters are black and the 

 sons barred — criss-cross inheritance. These 



I 



Fig. 39. Sex-linked inheritance in domesticated birds shown 

 here in a cross l^etween barred Plymouth Rock male and black 

 Langshan female. 



inbred give ])lack liens and black cocks, barred 

 hens and barred cocks. 



There is a case comparable to this found in 

 a wild species of moth. Abraxas grossulariata. 

 A wild variation of this ty])e is lighter in color 



