SEX INHERITANCE 83 
taining the normal allelomorphs of all these factors. 
In the case of all the factor-pairs, except abnormal 
and bar, the normal allelomorph dominates. There- 
fore, the females will appear normal for all characters 
except abnormal and bar, which are dominant. 
In the cat, Doncaster and Little describe a sex 
linked factor affecting the color. In man several 
characters, such as color blindness, hemophilia, and 
others less certainly identified have been found to 
follow the same scheme. 
A comparison of sex linkage in Abraxas with that 
in Drosophila shows that the mode of inheritance of 
sex linked characters is identical in these two cases, 
but the sex relations are exactly reversed. In the 
Abraxas type sex linked inheritance takes place in 
accord with the plan that the female is heterozygous 
in sex production. If the chromosome that carries 
this sex differentiator is called Z, and its mate in 
the female W, the formula for the male would be ZZ 
and that for the female WZ. The scheme follows: 
A} 
oS 
ZL 
Inheritance in Abraxas is illustrated in the follow- 
ing diagrams (Figs. 30 and 31), in which the common 
