the eye: the ova, in such cases (probably the majority), might also have a
double dose of sex-chromatin, the males a single dose. This theory,
however, is still open to the objection that the female gametes before
fertilisation, and half the male gametes, have the half quantity of
sex-chromatin which by hypothesis determines the male condition, so that
here again we have the male condition as something which is distinct from
the characteristics of the spermatozoon. But if this is the case, what is
the male condition? The parthenogenetic ovum of the bee is male, and yet
it is an ovum capable only of producing spermatozoa. If the single X
chromosomes is the cause of the development of spermatozoa in the male
bee, why does it not produce spermatozoa in the gametes of the female bee,
since when reduction takes place all these gametes have a single X
chromosome?

In biology, as in every other science, we must admit facts even when we
cannot explain them. The facts of what we call gravitation are obvious,
and any attempt to disregard them would result in disaster, yet no
satisfactory explanation of gravitation has yet been discovered: many
theories have been suggested, but no theory has yet been proved to be
true. In the same way it may be necessary to admit that two X chromosomes
result in the development of a female, and one X, or XY chromosomes result
in the development of a male. But Mendelians have omitted to consider what
is meant by male and female. The soma with its male and female somatic
characters has nothing to do with the question, since somatic
sex-differences may be altogether wanting, and moreover, the essential
male character, the formation of spermatozoa, is by the Mendelian
hypothesis due to descent of the male gametes from the original fertilised
or unfertilised _ovum_. The Mendelian theory therefore is that when an
ovum has two X sex-chromosomes it can only after a number of
cell-divisions, at the following reduction division, give rise to ova,