THE TRANSITION FROM CELL TO HUMAN BEING
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
single cavity, and usually develops but a single embryo.
TWINS
Sometimes two ovules are matured at the same time. If fecundated, two
embryos instead of one will develop, producing twins. Triplets and
quadruplets, the results of the maturing of three or four ovules at
the same time, occur more rarely. As many as five children have been
born alive at a single birth, but have seldom lived for more than a
few minutes.
GESTATION
The development of the ovule in the womb is known as gestation or
pregnancy. The process is one of continued cell division and growth,
and while it goes on the ovule sticks to the inner wall of the womb.
There it is soon enveloped by a mucous membrane, which grows around it
and incloses it.
THE EMBRYO
The _Primitive Trace_, a delicate straight line appearing on the
surface of the growing layer of cells is the base of the embryonic
spinal column. Around this the whole embryo develops in an intricate
process of cell division and duplication. One end of the Primitive
Trace becomes the head, the other the tail, for every human being has
a tail at this stage of his existence. The neck is marked by a slight
depression; the body by a swollen center. Soon little buds or "pads"
appear in the proper positions. These represent arms and legs, whose
ends, finally, split up into fingers and toes. The embryonic human
being has been steadily increasing in size, meanwhile. By the fifth
week the heart and lungs are present in a rudimentary form, and ears
and face are distinctly outlined. During the seventh week the kidneys
are formed, and a little later the genital organs. At two months,
though sex is not determined as yet, eyes and nose are visible, the
mouth is gaping, and the skin can be distinguished. At ten weeks the
sexual organs form more definitely, and in the third month sex can be
definitely determined.
THE FOETUS
At the end of its fourth month the embryo--now four or five inches
long and weighing about an ounce--is promoted. It receives the name of
foetus. Hairs appear on the scalp, the eyes are provided with lids,
the tongue appears far back in the mouth. The movements of the foetus
are plainly felt by the mother. If born at this time it lives but a
few minutes. It continues to gain rapidly in weight. By the sixth
month the nails are solid, the liver large and red, and there is fluid
in the gall bladder. The seventh month finds the foetus from twelve
and a half to fourteen inches long, and weighing about fifty-five
ounces. It is now well proportioned, the bones of the cranium,
formerly flat, are arched. All its parts are well defined, and it can
live if born. By the end of the eighth month the foetus has thickened
out. Its skin is red and covered by a delicate down; the lower jaw has
grown to the same length as the upper one. The convolutions of the
brain structure also appear during this month.
PLACENTA AND UMBILICAL CORD
During gestation the unborn infant has been supplied with air and
nourishment by the mother. An organ called the _Placenta_, a spongy
growth of blood vessels, develops on the inner point of the womb. To
this organ the growing foetus is moored by a species of cable, the
_Umbilical Cord_. This cord, also made up mainly of blood vessels,
carries the blood of the foetus to and from the _Placenta_, absorbing
it through the thin walls which separate it from the mother's blood.
Only through her blood can the mother influence the child, since the
Umbilical Cord contains no nerves. The Umbilical Cord, attached to the
body of the child at the navel, is cut at birth, and with the Placenta
is expelled from the womb soon after the child has been born. Together
with the Placenta it forms a shapeless mass, familiarly known as the
"afterbirth," and when it is retained instead of being expelled is apt
to cause serious trouble.
CHILDBIRTH OR PARTURITION
At nine month's time the foetus is violently thrust from that
laboratory of nature in which it has formed. It is born, and comes
into the world as a child. Considering the ordinary size of the
generative passages, the expelling of the foetus from the womb would
seem impossible. But Nature, during those months in which she enlarged
the womb to hold its gradually increasing contents, has also increased
the generative passages in size. She has made them soft and
distensible, so that an apparent physical impossibility could take
place, though it is often accompanied by intense suffering. Modern
medical science has made childbirth easier, but the act of childbirth
is usually accompanied by more or less suffering. Excessive pain,
however, is often the result of causes which proper treatment can
remove before and at the time of confinement.
TWILIGHT SLEEP
The so-called "Twilight Sleep," a modern development, by which the
pangs of childbirth are obviated by the administration of drugs or by
hypnotic suggestion, has its opponents and defenders. The advantage of
a painless childbirth, upon which the mother can look back as on a
dream, is evident. The "Twilight Sleep" process has been used with the
happiest results both for parent and child. Opponents of this system
declare that the use of powerful drugs may injure the child. A method
commended is the administration of a mixture of laughing gas and
oxygen, which relieves the mother and does not affect the child.
THE NEW-BORN INFANT
The average weight of the new-born child is about seven and a half
pounds. It is insensitive to pain for the first few days, and seems
deaf (since its middle ears are filled with a thick mucus) for the
first two weeks. During the first few days, too, it does not seem able
to see. The first month of its existence is purely automatic.
Evidences of dawning intelligence appear in the second month and at
four months it will recognize mother or nurse. Muscularly it is poorly
developed. Not until two months old is it able to hold up its head,
and not until three months does voluntary muscular movement put in an
appearance. The new-born's first self-conscious act is to draw breath.
Deprived of its usual means of supply it must breathe or suffocate.
Its next is to suck milk, lest it starve.
HEREDITY
We often find children who offer a striking resemblance to a paternal
grandfather, a maternal aunt or a maternal great-grandmother. This is
known as atavism. There are many curious variations with regard to the
inheritance of ancestral traits. Some children show a remarkable
resemblance to their fathers in childhood, others to their mothers.
And many qualities of certain individual ancestors appear quite
suddenly late in life. Everything may be inherited, from the most
delicate shadings of the disposition, the intelligence and the will
power, to the least details of hair, nails and bone structure, etc.
And the combination of the qualities of one's ancestors in heredity is
so manifold and so unequal that it is extremely difficult to arrive at
fixed conclusions regarding it. Hereditary traits and tendencies are
developed out of the energies of the original conjugated germ-cells
throughout life, up to the very day of death. Even aged men often show
peculiarities in the evening of their life which may be clearly
recognized as inherited, and duplicating others shown by their
forbears at the same period of life.
As has already been mentioned every individual inherits, generally
speaking, as much from his paternal as from his maternal progenitors.
This in spite of the fact that the tiny paternal germ-cell is the
only medium of transmission of the paternal qualities, while the
mother furnishes the much larger egg-cell, and feeds him throughout
the embryonic period.
THE ENGRAM
An interesting theory maintains that the external impressions made
upon an organism which reacts to them and receives them, might be
called _engrams_ or "inscriptions." Thus the impression of some object
we have seen or touched (let us say we have seen a lion) may remain
engraved on our mind as an impression. Hence every memory picture is
one of engrams, whether the impression is a conscious one or an
unconscious one. According to this same theory the reawakening of an
older impression is an _ecphory_. Some new stimulation may thus
ecphorate an old engram. Now the entire embryonal development of the
human child is in reality no more than a continuous process of
ecphoration of old engrams, one after another. And the entire complex
of our living human organism is made up entirely of these
energy-complexes engraved on our consciousness or subconsciousness.
The sum total of all these engrams, in a living human being, according
to the theory advanced, is given the name of _mnema_. That which the
child receives in the way of energies contained in the germ-cells from
its ancestors is his hereditary _mnema_. And that which he acquires in
the course of his own individual life is his acquired or individual
_mnema_.