In the functional processes alluded to in the preceding chapter, the

male germ-cell and the female germ-cell unite in a practically equal

division of substance. We say "practically" because the maternal and

the paternal influences are not equally divided in the offspring. One

or the other usually predominates. But, as a general rule, it may be

said that in the development of the embryonal life the process of cell

division proceeds in such a way that every germ of the child's future

organism represents approximately one-half maternal and one-half

paternal substance and energy.

In this process lies the true secret of heredity. The inherited

energies retain their full measure of power, and all their original

quality in the growing and dividing chromosomes (the chromosome is one

of the segments into which the chromoplasmic filaments of a

cell-nucleus break up just before indirect division). On the other

hand, the egg-substance of the female germ-cell, which is assimilated

by the chromosomes, and which is turned into _their_ substance by the

process of organic chemistry, loses its specific plastic vital energy

completely. It is in the same way that food eaten by the adult has

absolutely no effect on his qualitative organic structure. We may eat

ever so many beef-steaks without acquiring any of the characteristics

of an ox. And the germ-cell may devour any amount of egg-protoplasma

without losing its original paternal energy. As a rule a child

inherits as many qualities from its mother as from its father.

DETERMINATION OF SEX

Sex is determined after conception has taken place. At an early stage

of the embryo certain cells are set apart. These, later, form the sex

glands. Modern research claims to have discovered the secret of

absolutely determining sex in the human embryo, but even if these

claims are valid they have not as yet met with any general

application.

EARLY DEVELOPMENT

Some twelve days after conception, the female ovule or egg, which has

been impregnated by the male spermatazooen, escapes from the ovary

where it was impregnated, and entering a tube (Fallopian) gradually

descends by means of it into the cavity of the womb or uterus. Here

the little germ begins to mature in order to develop into an exact

counterpart of its parents. In the human being the womb has only a




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