&2 SEX INHERITANCE 
have already been given; that of white eyes is typical 
of all the rest. The main facts may be restated 
here. If a white eyed male is bred to a red eyed 
female the offspring are red eyed (Fig. 9). If these 
are inbred all of the F, daughters are red eyed, but 
half of the sons are white eyed and half red eyed. 
In a word, the grandfather transmits his characters 
visibly to half of his grandsons but to none of his 
granddaughters. 
In the reciprocal cross (Fig. 10), a white eyed 
female bred to a red eyed male produces the criss- 
cross result of red eyed daughters and white eyed 
sons. These give white and red eyed males and fe- 
males in equal numbers. On the assumption that the 
factor for white eyes is carried by the sex chromo- 
somes the inheritance of white eyes can be readily 
understood. It will be observed that a female trans- 
mits to each of her sons one of her X chromosomes 
with all the factors contained in it. Her sons will 
show all of these sex linked characters whether they 
be dominant or recessive since they receive no other 
X to dominate those characters and the Y contains 
no dominant factor. For example, if a stock be 
made up pure for yellow body color, white eyes, ab- 
normal abdomen, bifid wings, sable body color, forked 
spines and bar eyes, and if such a female be bred 
to a wild male, all of her sons will be yellow, 
white, abnormal, bifid, sable, forked and bar. The 
daughters, however, wil! receive not only this chro- 
mosome from their mother, but will also receive a 
chromosome from the wild male (their father) con- 
