the time of fertilization were developed under the influence of the
nucleus, which in turn got them half and half from its male and female
parents. These characters carried by the female across one generation
are so rudimentary that they are completely covered up, in the
developing embryo, by those of the new nucleus formed by the union of
the sperm with the egg in fertilization.

In case fertilization does not take place, this rude beginning in the
egg is lost. Since no characteristic sex is assumed until after
fertilization, we may say that life begins as neuter in the individual,
as it is presumed to have done in the world. It will occur to those
inclined to speculation or philosophic analysis that by the word
"neuter" we may mean any one or all of three things: (a) neither male
nor female; (b) both male and female, as yet undifferentiated, or (c)
potentially either male or female. Clearly, the above explanation
assumes a certain _germinal_ specialization of the female to
reproduction, in addition to the body specialization for the
intra-parental environment (in mammals).

A tremendous amount of laboratory experimentation upon animals has been
done in late years to determine the nature of sex. For example,
Goodale[16] castrated a brown leghorn cockerel twenty-three days old
and dropped pieces of the ovary of a female bird of the same brood and
strain into the abdominal cavity. These adhered and built up circulatory
systems, as an autopsy later showed. This cockerel, whose male sex
glands had been exchanged for female ones, developed the female body,
and colouration so completely that expert breeders of the strain
pronounced it a female. He found that simply removing the female sex
glands invariably led to the development of spurs and male plumage. But
simple removal of the male sex glands did not alter plumage. To make