SEX-LINKAGE IN FOWLS 503 
The matings made and the offspring produced were as follows: 
I. Columbian Wyandotte ~ X Brown Leghorn 9—— 9 gray & 
3 gray 2 
II. Brown Leghorn & X Columbian Wyandotte 9 —— 10 gray 7 
i 8 red Q 
III. Brown Leghorn & X Red Fi 2 ===> 3) ial i 
3 red Q 
IV. Gray Fi & (from II) X Brown Leghorn 9 == gray 
3 
5 duckwing 
5 redo 
7 gray 2 
1 silver gray 2 
1 brown duckwing ? 
2 red 9 
2 
brown @ 
EXPLANATION OF RESULTS 
As I pointed out in my preliminary note, there is here at least 
one sex-linked factor, which I then called G, causing the two 
types of F, females. The F, generation agrees with this, mating 
III giving no grays, and mating IV both gray and non-gray 
males and females. But there are obviously other factors con- 
tributing to the F, result, which is decidedly complex, as has 
so often been found to be the case in experiments with fowls. 
I do not, therefore, feel justified in giving more than a tentative 
explanation of the results, since the numbers are small, and only 
a few of the many crosses which would be required to test any 
explanation have been made. The following will, however, 
cover the results obtained, and is the simplest scheme that I 
have been able to work out. 
Let us assume that the Columbian Wyandotte carries an 
inhibitor, 7, for red in all parts of the body, with the exceptions 
noted below. This is the G of my earlier paper. The Wyan- 
dotte also carries another sex-linked inhibitor, V, which prevents 
the production of red in the neck (and saddle of the male), not 
affecting the other parts. This is probably the factor described 
by Davenport (’11) as found in Dark Brahmas. Birds not carry- 
