Taboo and Genetics | Page 7

evidence in this way, merely to help in clearing up points
about human biology, we need not be entirely limited to mammals. Some sex phenomena
are quite general, and may be drawn from the sexual species most convenient to study
and control in experiments. When we get away from mammalian forms, however, we

must be very sure that the cases used for illustrations are of general application, are
similar in respect to the points compared, or that any vital differences are understood and
conscientiously pointed out.
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.
BIBLIOGRAPHY FOR CHAPTER I
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. Schäfer, 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.
CHAPTER II
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."
It will be seen at once that this seems to preclude any possibility of a child's inheriting
from its parents anything which these did not themselves inherit. The bodies of each
generation are, so to speak, mere "buds" from the continuous lines of germplasm. If we
develop our muscles or our musical talent, this development is of the body and dies with
it, though the physical basis or capacity we ourselves inherited is still in the germplasm
and is therefore passed along to our children. We may also furnish our children an
environment which will stimulate their desire and lend opportunity for similar or greater
advancement than our own. This is social inheritance, or the product of
environment--easy to confuse with that of heredity and very difficult to separate,
especially in the case of mental traits.
It will likewise become clear as we proceed that there is no mechanism or relationship
known to biology which could account for what is popularly termed "pre-natal
influence." A developing embryo has its own circulation, so insulated from that of the
mother that only a few of the most virulent and insidious disease germs can ever pass the
barrier. The general health of the mother is of utmost importance to the vitality, chances
of life, constitution and immunity from disease of the unborn child. Especially must