ffectiveness of the genital organs." This
connection is so profound that it may be traced very widely throughout the
organic world.

The connection between pigmentation and sexual activity is very ancient.
Even leaving out of account the wedding apparel of animals, nearly always
gorgeous in scales and plumage and hair, the sexual orifice shows a more
or less marked tendency to pigmentation during the breeding season from
fishes upward, while in mammals the darker pigmentation of this region is
a constant phenomenon in sexually mature individuals.[159]

In the human species both the negative standard of castration and the
positive standard of puberty alike indicate a correlation of this kind.
Those individuals in whom puberty never fully develops and who are
consequently said to be affected by infantilism, reveal a relative absence
of pigment in the sexual centers which are normally pigmented to a high
degree.[160] Among those Asiatic races who extirpate the ovaries in young
girls the skin remains white in the perineum, round the anus, and in the
armpits.[161] Even in mature women who undergo ovariotomy, as Kepler
found, the pigmentation of the nipples and areola disappears, as well as
of the perineum and anus, the skin taking on a remarkable whiteness.

Normally the sexual centers, and in a high degree the genital orifice,
represent the maximum of pigmentation, and under some circumstances this
is clearly visible even in infancy. Thus babies of mixed black and white
blood may show no traces of negro ancestry at birth, but there will always
be increased pigmentation about the external genitalia.[162] The linea
fusca, which reaches from the pubes to the navel and occasionally to the
ensiform cartilage, is a line of sexual pigmentation sometimes regarded as
characteristic of pregnancy, but as Andersen, of Copenhagen, has found by
the examination of several hundred children of both sexes, it exists in a
slight form in about 75 per cent. of young girls, and in almost as large a
proportion of boys. But there is no doubt that it tends to increase with
age as well as to become marked at pregnancy. At puberty there is a
general tendency to changes in pigmentation; thus Godin found that in 28
per cent, adolescent changes occurred in the eyes and hair at this period,
the hair becoming darker, though the eyes sometimes become lighter. Ammon,
in his investigation of conscripts at the age of 20 (_post_, p. 196),
discovered the signi