seeks the female and physicians generally believe that men
are sexually more active than women,[58] though woman's need of
reproduction is greater,[59] and celibacy unquestionably impresses
the character of women more deeply than that of man. Additional
evidence of the greater sexual activity of man is furnished by
the overwhelmingly large proportion of the various forms of sexual
perversion reported by psychiatrists in the male sex.

Pathological variations do not become fixed in the species, because
of their disadvantageous nature, but their excess in the male is, as
we have seen in the case of variations which have become fixed, an
expression of the more energetic somatic habit of the male.

A very noticeable expression of the anabolism of woman is her tendency
to put on fat. "Women, as a class, show a greater tendency to put on
fat than men, and the tendency is particularly well marked at puberty,
when some girls become phenomenally stout."[60] The distinctive beauty
of the female form is due to the storing of adipose tissue, and the
form even of very slender women is gracefully rounded in comparison
with that of man. Bischoff found the following relation between muscle
and fat in a man of 33, a woman of 22, and a boy of 16, all of whom
died accidentally and in good physical condition:

Man Woman Boy
Muscle 41.18 35.8 44.2
Fat 18.2 28.2 13.9

The steatopyga of the women of some races and the accumulation of
adipose tissue late in life are quasi-pathological expressions of this
tendency.

In tracing the transition from lower to higher forms of life, we find
a great change in the nature of the blood, or what answers to
the blood, and the constitution of the blood is some index of the
intensity of the metabolic processes going on within the organism. The
sap of plants is thin and watery, corresponding with the preponderant
anabolism of the plant. "Blood is a peculiar kind of sap," and there
is almost as much difference between this sap in warm-blooded and
cold-blooded animals as between the latter and plants. Rich, red blood
characterizes the forms of life fitted for activity and bursts of
energy. In his exhaustive work on the blood Hayem has given a summary
of the results of the investigations of chemists and physiologists
on the differences in the composition of the blood in the two s