Wilson — The Multiple Qoupling of Mendelian Factors. 373 



should give 



Hybrid 



silver 

 male. 



MM 

 E h 

 S g 



English silver males. 



MM 

 E E 



S 8 



MM 

 E E 



8 g 



MM 

 E h 



8 8 



IV. 



and 



MM 

 E h 

 8 g 



English (pure) 

 silver 

 female. 



English English English 

 silver gold silver 



females. females. 



English 

 gold 



Mr. Jones got English silver males and females, and English gold females. 

 He writes that this experiment was carried out by several people, and that 

 taken altogether the proportions were 4:3:1. The proportion of silver 

 to gold females should have been 1 : 1. The discrepancy is likely to be 

 accounted for by some of the females not having been pure for English type. 

 The English silver breed is only about ten years old, and undoubtedly many 

 hens which breeders consider pure are not pure genetically. 



It will be well to bring the foregoing result into line with previous work. 

 Castle and Pearl showed that the American Barred Plymouth Kocks are 

 merely black fowl having portions of their feathers lacking colour, i.e. barred. 

 The " silver " Campine is therefore a black fowl with colourless bars on its 

 plumage; and the black colour is dominant to tiie golden. Then, putting 

 Bl for black and Bd for barred, a silver Campine hen of the Belgian bieed 

 is factorially represented by 



M 

 b 

 Bl 



Bd 



Note. — It will be noticed that experiments II and IV are apparently the 

 same, but, in the former, the hens, though hybrids, were necessarily pure 

 for E, while, in the latter, the hens were not necessarily pur ? for E, though 

 " pure bred" from the breeder's standpoint. 



SCIENT. PROC. E.D.S., VOL. XIV., NO. XXX. 



