Too much stress cannot be laid upon the point that
such animal data, carefully checked up with the human
material, cannot safely be used for any other purpose
than to discover what the facts are about the human
body. When the discussion of human social institutions
is taken up in Part II, the obvious assumption will
always be that these rest upon human biology, and
that we must not let our minds wander into vague analogies
concerning birds, spiders or crustacea.
1. Loeb, Jacques. Artificial Parthenogenesis
and Fertilization. Chicago, 1913.
2. Loeb, Jacques. The Organism as a Whole.
N.Y., 1916, p. 125—brief summary of results
of [1].
3. Bower, Kerr & Agar. Sex and Heredity.
N.Y., 1919, 119 pp.
4. Schaefer, E.A. Nature, Origin and Maintenance
of Life. Science, n.s., Vol. 36, pp. 306 f.,
1912.
5. Guyer, M.F. Being Well-Born. Indianapolis,
1916; p. 123.
SEX IN TERMS OF INTERNAL SECRETIONS
Continuity of germplasm; The sex chromosome; The internal
secretions and the sex complex; The male and the female
type of body; How removal of sex glands affects body
type; Sex determination; Share of egg and sperm in
heredity; Nature of sex—sexual selection
of little importance; The four main types of secretory
systems; Sex and sex-instincts of rats modified by
surgery; Dual basis for sex; Opposite-sex basis in
every individual; The Free-Martin cattle; Partial
reversal of sex in man.
In Chapter I, the “immortality” of the
protoplasm in the germ cells of higher animals, as
well as in simpler forms without distinct bodies, was
mentioned. In these higher animals this protoplasm
is known as germplasm, that in body cells as
somatoplasm.
All that is really meant by “immortality”
in a germplasm is continuity. That is, while
an individual may consist of a colony of millions of
cells, all of these spring from one cell and it a germ
cell—the fertilized ovum. This first
divides to form a new group of germ cells, which are
within the embryo or new body when it begins to develop,
and so on through indefinite generations. Thus
the germ cells in an individual living to-day are
the lineal descendants, by simple division, of the
germ cells in his ancestors as many generations, or
thousands of generations, ago as we care to imagine.
All the complicated body specializations and sex phenomena
may be regarded as super-imposed upon or grouped around
this succession of germ cells, continuous by simple
division.
The type of body in each generation depends upon this
germplasm, but the germplasm is not supposed to be
in any way modified by the body (except, of course,
that severe enough accidents might damage it).
Thus we resemble our parents only because the germplasm
which directs our development is a split-off portion
of the same continuous line of germ cells which directed
their development, that of their fathers, and so on
back. This now universally accepted theory is
called the “continuity of the germplasm.”
