SEX-LINKAGE IN FOWLS Hillis) 
NF nF normal @ 
NF nf (nF) Nf) normal ¢ ” (gametes) 
NF NF nel Q 
NF nF normal 92 
NF nf normal o@ 
nF nf dwarf 
(NF nF normal @) 
(nF nF dwarf ?) 
(NF Nf normal <) 
(nF Nf normal <) 
The actual numbers for families containing dwarfs is as follows: 
Normal @ normal dwarf 9° dwarf o 
25 49 & 20m) 
This gives a preponderance of normal males as against dwarf 
males, but it should be remembered that for every dwarf female 
due to crossing over there is a normal male produced, and sec- 
ondly, the mutant is obviously not a very viable one, so that a 
shortage is perhaps not surprising, especially in such compar- 
atively small numbers. The fact that there are nearly as many 
dwarf males as normal females is obviously due to the cireum- 
stance that the males of both kinds taken together are more than 
twice as numerous as the females. 
In plants Correns (’07) and Shull (10, 711) have shown that 
in certain dioecious species of Bryonia and Lychnis it is the male 
which is heterozygous. In the absence of cytological evidence 
or sex-linkage phenomena a chromosome interpretation of these 
cases would perhaps be out of place. 
SUMMARY 
There is a sex-linked factor carried by the Columbian Wyan- 
dotte—an inhibitor for red in the plumage. This breed proba- 
bly also carries another sex-linked factor, an inhibitor for red 
in the neck. It apparently carries a pattern factor inhibiting 
the breast color, and, in the female, the stippled back of the 
Brown Leghorn. 
The silver gray color is probable epistatic to the Jungle fowl 
or brown color. 
