metabolism. It is a general law in the courtship of the sexes that the
male seeks the female. The secondary sexual characters of the male are
developed with puberty, and in some cases these sexual distinctions
come and go with the breeding season. What we know as physiological
energy is the result of the dissociation of atoms in the organism;
expressions of energy are the accompaniment of the katabolic or
breaking-up process, and the brighter color of the male, especially at
the breeding season, results from the fact that the waste products of
the katabolism are deposited as pigments.

When we compare the sexes of mankind morphologically, we find a
greater tendency to variation in man:[31]

All the secondary sexual characters of man are highly variable,
even within the limits of the same race; and they differ much in the
several races.... Numerous measurements carefully made of the stature,
the circumference of the neck and chest, the length of the backbone
and of the arms, in various races ... nearly all show that the males
differ much more from one another than do the females. This fact
indicates that, as far as these characters are concerned, it is the
male which has been chiefly modified, since the several races diverged
from their common stock.[32]

Morphologically the development of man is more accentuated than that
of woman. Anthropologists, indeed, regard woman as intermediate in
development between the child and the man.

The outlines of the adult female cranium are intermediate
between those of the child and the adult man; they are softer,
more graceful and delicate, and the apophyses and ridges for