370 Scientific Proceedings, Royal Dublin Society, 



plain. From this it can be inferred that barred females, though pure bred, 

 according to the poultry breeders, are not genetically pure for barring, but 

 carry a factor for plainness in addition. Pure bred barred fowl may there- 

 fore be represented as follows : — 



Males. Females. 



MM M F 



B B B p 



Nor can the females be bred pure for barring : they carry always a factor for 

 plainness. Males, however, can be bred pure either for barring or plainness. 

 Thus the four following kinds of fowl may be represented factorially as 

 follows : — 



In addition to this there is the striking phenomenon that the barred 

 progeny of barred females and plain males are all males, while the plain 

 progeny are all females ; and of this phenomenon the only possible explana- 

 tion is that, while the factor M can associate with either B or p, F can 

 associate with p only. The latter two are coupled together. Surrounding 

 the factors F and p with a closed bracket, to prevent confusion, we may 

 therefore represent the barred males and females factorially as — 



Males. Females. 



I — I 



MM M\F\ 



B B b\p\ 

 I I 



The English Campines are descended from Belgian stock, the first of which 



were brought to England about a quarter of a century ago. The Belgian 



stock were of two kinds as regards colour : a silver and a gold, and both kinds 



were barred. But, while the hens were barred all over, excepting on the 



hackle, the cocks were unbarred not only on the hackle, but also on the back 



and tail. Occasionally cocks appeared as fully barred as the hens, 



but sucli were not preserved by the Belgian breeders. English breeders, 



on the other hand, preferred these fully barred males, and, preserving 



them, eventually produced silver and gold varieties of the breed wliioh 



were equally fully barred in both sexes. The fully barred fowl are spoken of 



as of " English type," the others as of " Belgian type." 



The fact that the Belgian hens are always of English type, while the 



cocks, which are usually Belgian, may be of English type occasionally, is 



clear evidence that the factor for English type is coupled with femalenese. 



