, associated with increased metabolism, helps to produce
males.

In males, the secretion of the sex glands alone seems to be of
particular importance, again suggesting this idea of "strength" which
comes up over and over again. Removal of these glands modifies the male
body much more profoundly than it does the female.[8] It is quite
generally supposed that the action of this one secretion may have much
to do with the superior size and vigour of males. For example, Paton
says[9]: "The evidence thus seems conclusive that in the male the gonad,
by producing an internal secretion, exercises a direct and specific
influence upon the whole soma, increasing the activity of growth,
moulding the whole course of development, and so modifying the
metabolism of nerve and muscle that the whole character of the animal is
altered." It used to be said that the male was more "katabolic," the
female more "anabolic." These expressions are objectionable, inasmuch as
they hint that in a mature organism, with metabolism rather stable,
tearing down, or katabolism, could go on faster than building up, or
anabolism, or that one of two phases of the same process might go on
faster than the other. It seems safer to say merely that a lower
metabolism in the female is accompanied by a tendency to store
materials.

A long time will doubtless be required to work out the details of
differences in metabolism in the two sexes. Some of the main facts are
known, however, and the general effects of the two diverse chemical
systems upon the life cycles of the sexes are quite obvious. What we
call the "quantitative theory of sex" has, besides a place in exact
science, an interesting relation to the history of biological thought,
especially as applied to society. It is thus in order to state as
clearly as possible what it now is; then, so that no one may confuse it
with what it is not, to run over some of the old ideas which resemble
it.

Experiments with transplanted sex glands, with sex-gland extracts
(testicular and ovarian) and the observation of infusions of a male-type
blood-stream into a female body, as occurs in nature in some cattle and
in the so-called human "hermaphrodites," indicate a gross chemical
difference between the respective determiners for femaleness and for
maleness. So the chemicals involved, though not yet isolated, must be
presumed to be _qualitatively_ different, since they produce such
different results.

But such experiments