The question remains, therefore, where are the factors of the somatic
sex-characters? One suggestion which might be made is that the female
characters are present in the _Y_, in this case female producing
chromosome, or, if the female characters are merely negative, that the
male characters are in the _X_ chromosome, but only show themselves in the
homozygous condition, thus:--

FEMALE x MALE
XY XX
| \/ |
| /\ |
XX YX
MALE FEMALE

The male characters in the male, _XX_, would appear because present in two
chromosomes, but would be recessive in the female because present only in
one chromosome. The validity of this scheme, however, is disproved by the
fact that males can transmit the female characters of their race, as in
the case mentioned by Doncaster where a male _Nyssia zonaria_ when crossed
transmits the wingless character of its own female.

Another, perhaps better, suggestion is that the somatic characters of both
sexes are present in each. Then as each somatic cell is descended without
segregation from the fertilised ovum, we may suppose that the presence of
the sex-chromosomes in the somatic cells themselves in some way determines
whether male or female characters shall develop, without the aid of any
hormones from the gonads. This theory would be quite compatible with
the belief that adaptive somatic sex-characters may be due to external
stimulation, for supposing that the hypertrophy or modification is
conveyed to the determinants in the gametocytes, and was confined to