On the zygotic constitution of dominant and recessive whites etc. 237 
2. F, yellow paired inter se. 
I. ssYY xssYY =ssYY =all Y. 
Ze) xsYy=ssYY --ssYy=alY. 
3. ssYy x ssYy =ssYY -++ 2sYy+ssyy=3 Y:1 W. 
F, will, therefore, be (all w), (13 W:3 Y), (6 W:2 Y), (3 W:1 Y), 
(1 W:ı Y) and (7 W:1 Y) in the white matings, and (all Y), (3 Y: 1 W), 
in the yellow matings, that is to say, some white F, matings give 
all white F, offspring, while others give a mixed F,, consisting of 
white and yellow in various proportions, such as 13 W:3 Y, 6 W:2 Y, 
3 W:1 Y, 1 W:1 Y, 7 W:1Y. In like manner, yellow matings give rise 
to two kinds of F, offspring, one being all yellow and the other a 
mixture of white and yellow in the ratio 1:3. In Fs, therefore, the 
white seems to be epistatic to the yellow in white matings; the case 
is quite reversed in the yellow matings in which the yellow is epistatic 
to the white. The behaviour of the white character is apparently 
irregular, but it is strictly Mendelian as the above formulae show. 
Résumé: 
Wx Ww 
F, = WwW 
| 
r= (13 W : 3 Y) 
Fy =W (13 W:3 Y) (6W:2 Y) (3 W:1 Y) (1W:1 Y) (7 W:1 Y) we (Essay yh 
Considering the above, we may conjecture that there probably 
exist many whites which differ in their zygotic constitution from one 
another, but remain true to the whiteness. We may enumerate the 
following whites: 
I. SSYY — Homozygous dominant white, with homozygous colour 
factor. 
2. ssyy = Homozygous recessive white, which is entirely destitute 
of the suppressing and the colour factors. Most of the Japanese and 
Chinese whites belong to this category. 
3. SSyy = Homozygous dominant white, without the colour factor. 
4. SSYy — Dominant white, with the colour factor in a hetero- 
zygous condition. 
5. Ssyy = White, with no colour factor but with the suppressing 
factor in a heterozygous form. 
6. In the case where the white form was selected from certain 
breeds in which both white and yellow are produced, there will be 
heterozygous whites such as SsYy and SsYY which do not breed true 
to parents. 
