Dunn : Color Inheritance In Fowls 



Buff Male Columbian Female 



27 



Columbian Male 



Buff Female 



THE RECIPROCAL CROSS 



Figure 14. When the male is bufif and the female Columbian all females of the first 

 generation are bufT, while the males are Columbian like their mother. This mode of sex- 

 linked inheritance is explained by assuming that there are two distinct sex-determiners 

 located in the W-chromosome and the Z-chromosome respectively. The W-chromosome 

 has not been shown to carry any other factors than those determining sex. Two Z-chromo- 

 somes produce a male, a W- and a Z-chromosome produce a female. That is, all individuals 

 that carry a W-chromosome are females. Therefore the W-chromosome is inherited in the 

 maternal line only. The other sex-determiner must come from the male parent, carrying 

 with it his tyipical color factor. Thus even though bufif is recessive to Columibian, all 

 females of the first generation of this cross are buff, because that is the only color 

 determiner present in the first generation females. 



the offspring of this cross was inter- 

 esting since in both parent varieties 

 the males and females are ahke in 

 color and pattern. 



The reciprocal cross of Columbian 

 female by black male produced like- 

 wise all black chicks. As adults the 

 males were similar to the sons of the 

 first cross described, i. e.. black with 



white in hackle, bow, and saddle in a 

 pattern approximating that of the 

 Dark Brahma or Silver Duckwing. 

 The females from this cross were self 

 black. One of them showed a few 

 red-bordered feathers under the lower 

 jaw. There was no appearance of sil- 

 vering in the plumage nor any de- 

 velopment of pattern. 



