and females unite and produce eggs. The creatures produced by the
hatching of eggs are neither males nor perfect females. They are
_imperfect females_. They are all alike, so that no sexual union occurs.
Instead of laying eggs, they produce live young like themselves, which
appear to be developed from internal buds similar to the external buds
of the polyp. After this method of reproduction has continued for eight
or ten generations, a few perfect individuals appear, and the first
process is repeated.
The common honey-bee affords another illustration like the last. A
virgin queen sometimes lays eggs, which always produce males, or drones.
After union with a male, she lays eggs in the royal cells which become
perfect females like herself. She also seems to have the power to lay,
at will, unfecundated eggs, from which drones are produced.
Human Beings Are Developed Buds.--It has been very aptly suggested by
an eminent physiologist that the ovum and zoosperm may be correctly
considered as internal buds. Thus it would appear that generation is
universally a process of budding. A child is but a compound bud, an
offshoot from its parents. This idea is not a mere fancy, but has a
scientific basis. As all the exquisite details of the most beautiful
flower are in essence contained within the tiny bud which first makes
its appearance, so is the developed human being, the full-grown man
or woman, virtually contained within the tiny cell called the ovum after
it has been impregnated or fecundated by the zoosperms. In short, men
and women are blossoms in a strictly scientific sense.
Fecundation in Hermaphrodites.--The process of fecundation in
hermaphrodite animals is very peculiar. In some cases, as in the snail,
the union of two individuals is usually necessary, though each
possesses both kinds of organs. In other cases, as in the tape-worm,
the oyster, and numerous other mollusks, a single individual has the
power to fertilize its own ova, thus being wholly independent. Human
hermaphrodites are usually so deformed that fecundation is not effected,
which is a fortunate safeguard against the multiplication of such
monstrosities.
Development.--After the union of the two elements, known as fecundation
or _conception_, if the conditions are favorable, development occurs,
and the little germ is in due process of time developed into an
individual which is an exact counterpart of its parents. During this
developmental process, the embryonic being is variously treated by
different classes of animals.
Unprotected Development.--Most fishes and reptiles discharge their ova
before fecundation, or soon after, and pay no further attention to them.
The fish deposits its eggs in a little hollow scooped out in the gravelly
bed of a stream, or sows them broadcast upon the waters. The turtle
buries its eggs in the sand, and leaves them to be hatched by the sun.
The ostrich disposes of her eggs in the same way. Many other species
of animals pay no regard to the protection of the germs which are
destined, if placed under favorable conditions, to become individuals
like themselves.
Partial Protection of the Ovum.--There are some exceptions, however,
to this general rule among fishes and reptiles. Even fishes manifest
a degree of parental solicitude in certain cases. The male of a species
of South American fish gathers up the eggs after fecundation has taken
place, and carries them in his mouth until they are hatched. Another
male fish carries the eggs of his mate in a little pouch upon the lower
and posterior part of his body.
Certain species of frogs carry their eggs wound about their legs; others
suspend them from the abdomen. Another variety carries its young upon
its back. Prof. Wyman describes a "swamp toad" which patiently takes
the eggs of his mate, one by one, and fastens them upon her back,
observing great regularity in arrangement. These several devices are
evidently for the purpose of protecting, in some degree, the young
individual during the helpless stage of its existence.
Development in the Higher Animals and Man.--Higher animals are less
prolific, and their development is a more complicated process; hence,
their young need greater protection, and, for this reason, the ova,
instead of being discharged from the body of the female after
fecundation, are retained.[3] As we have seen that a suitable
receptacle is sometimes provided outside of the body, so now a
receptacle is needed, and is provided in the interior of the body of
the female. This receptacle is called
[Footnote 3: Curious examples of internal development sometimes occur
in animals which usually deposit eggs. Snakes have been known to produce
both eggs and living young at the same time. At the annual meeting of
the American Society for the Advancement of Science, at Detroit, Mich.,
in August, 1875, we had the pleasure of examining a specimen, exhibited
by Prof. Wilder, of a chick which had undergone a considerable degree
of development within the ovary of the hen. It had a head, a rudimentary
brain, and internal viscera, but no feathers nor limbs. It was, in fact,
an egg hatched before it had been laid. The anomaly excited much
interest at that time and since among biologists.]
The Uterus.--This is a hollow, pear-shaped organ, located in the median
line, just behind the bladder, between it and the rectum. It is
supported in place by various ligaments and by the juxtaposition of
other organs. Its larger end is directed upward, and communicates upon
each side with a very narrow tube which is prolonged outward on either
side until it nearly touches the ovary of the same side. Its lower and
smaller end fills the internal extremity of the passage previously
described as the vagina. When an ovum is matured, it escapes from the
ovary into the narrow tube referred to, called the _Fallopian tube_,
and passes down into the cavity of the uterus. If fecundation does not
occur, it is expelled or absorbed after six to twelve or fourteen days.
If copulation occurs, however, zoosperms are brought into the cavity
of the uterus, and, coming in contact with the ovum, fecundate it. This
is _conception_. When the natural process is allowed to proceed,
development occurs.
Uterine Gestation.--This is the term applied to the process last
referred to. We shall not attempt to describe in detail this most
wonderful and intricate of all living processes; but will sketch only
the chief points, leaving the reader who would obtain a more complete
knowledge of the subject to consult any one of the numerous
physiological and obstetrical works which deal with it in a very
exhaustive manner.
As soon as the ovum is impregnated by the male element, it begins a
process of symmetrical division. The first division produces two cells
out of the single one which first existed. By the next division, four
segments are produced; then eight, sixteen, etc. While this process
is going on, the ovum becomes adherent to the internal wall of the uterus,
and is soon enveloped by its mucous membrane, which grows up about and
incloses it.
The Primitive Trace.--When the process of segmentation has advanced
to a certain point, the cells are aggregated together in a compact layer
at the surface. Soon a straight line appears upon this layer, which
is called the _primitive trace_. This delicate line becomes the basis
for the spinal column; and upon and about it the whole individual is
developed by an intricate process of folding, dividing, and
reduplication of the layer of cells. One end of the line becomes the
head, and the other becomes the tail. Even man has a caudal appendage
at an early stage of his existence. After a further lapse of time, little
excrescences, buds, or "pads," appear in the proper positions to
represent the arms and legs. After further development the ends split
up into fingers and toes, and by the continued development of the parts,
perfect arms and legs are formed.
Curious Relation to Lower Animals.--It is a very remarkable fact that
in the lower animals we have numerous examples in which the permanent
condition of the individual is the same as some one of the stages through
which man passes in the process of development. The same author
previously quoted makes the following interesting statements:--
"The webbed feet of the seal and ornithorhynchus typify the period when
the hands and feet of the human embryo are as yet only partly subdivided
into fingers and toes. Indeed, it is not uncommon for the 'web' to
persist to some extent between the toes of adults; and occasionally
children are born with two or more fingers or toes united to their tips.
"With the seal and the walrus, the limbs are protruded but little beyond
the wrist and ankle. With the ordinary quadrupeds, the knee and elbow
are visible. The cats, the lemurs, and the monkeys form a series in
which the limbs are successively freed from the trunk, and in the
highest apes they are capable of nearly the same movements as the human
arm and leg, which, in their development, passed through all these
stages."
Simplicity of Early Structures.--The first structures formed are
exceedingly simple in form. It is only by slow degrees that the great
complicity which characterizes many organs is finally attained. For
example, the heart is at first only a straight tube. By enlargement
and the formation of longitudinal and transverse partitions, the fully
developed organ is finally produced. The stomach and intestines are
also at first but a simple straight tube. The stomach and large
intestine are formed by dilatation; and by a growth of the tube in length
while the ends are confined, the small intestines are formed. The other
internal organs are successively developed by similar processes.
The Stages of Growth.--At first insignificant in size--a simple cell,
the embryonic human being steadily increases in size, gradually
approximating more and more closely to the human form, until, at the
end of about nine calendar months or ten lunar months, the new
individual is prepared to enter the world and begin a more independent
course of life. The following condensation of a summary quoted by Dr.
Austin Flint, Jr., will give an idea of the size of the developing being
at different periods, and the rate of progress:--
At the end of the third week, the embryon is a little less than
one-fourth of an inch in length.
At the end of the seventh week, it is three-fourths of an inch long.
The liver, lungs, and other internal organs are partially formed.
At the eighth week, it is about one inch in length. It begins to look
some like a human being, but it is impossible to determine the sex.
At the third month, the embryon has attained the length of two to two
and one-half inches. Its weight is about one ounce.
At the end of the fourth month, the embryon is called a fetus. It is
from four to five inches long, and weighs five ounces.
At the fifth month, the fetus is nearly a foot long, and weighs about
half a pound.
At the sixth month, the average length of the fetus is about thirteen
inches, and its weight one and a half to two pounds. If born, life could
continue a few minutes.
At the seventh month, the fetus is from fourteen to fifteen inches long,
and weighs two to three pounds. It is now viable (may live if born).
At the eighth month, the length of the fetus is from fifteen to sixteen
inches, and its weight from three to four pounds.
At the ninth month, the fetus is about seventeen inches long, and weighs
from five to six pounds.
At birth, the infant weighs a little more than seven pounds, the usual
range being from four to ten pounds, though these limits are sometimes
exceeded.
Duration of Gestation.--The length of time required for the development
of a human being is usually reckoned as about forty weeks. A more precise
statement places it at about two hundred and seventy-eight days. This
limit is often varied from. Cases have occurred in which a much longer
time has been required, and numberless cases have occurred in which
human beings have been born several weeks before the expiration of the
usual time, as stated. There is some uncertainty respecting the exact
length of the period of gestation, which grows out of the difficulty
of determining, in many cases, the exact time when conception takes
place.
Uterine Life.--The uterine life of the new individual begins with the
impregnation of the ovum, which occurs the instant it is brought in
contact with the zoosperms of the male. While in the uterus, the young
life is supported wholly by the mother. She is obliged to provide not
only for her own sustenance, but for the maintenance of her child. And
she must not only eat for it, but breathe for it as well, since it
requires a constant and adequate supply of oxygen before birth as much
as afterward.
How the Unborn Infant Breathes.--Oxygen and nutriment are both supplied
to it through the medium of an organ called the _placenta_, which is
a spongy growth composed almost entirely of blood-vessels, and is
developed upon the inner wall of the uterus, at the point at which the
ovum attaches itself after fecundation. The growing fetus is connected
with this vascular organ by means of a sort of cable, called the
_umbilical cord_. The cord is almost entirely composed of blood-vessels
which convey the blood of the fetus to the placenta and return it again.
The fetal blood does not mix with that of the mother, but receives oxygen
and nourishment from it by absorption through the thin walls which alone
separate it from the mother's blood.
The umbilical cord contains no nerves, as there is no nervous connection
between the mother and the child. The only way in which the child can
be influenced by the mother is through the medium of the blood, to
changes in which it is very susceptible, as we shall see more clearly
hereafter.
The cord is attached to the body of the child at the point called the
_navel_, being cut off at birth by the _accoucheur_. With the placenta,
it is expelled soon after the birth of the child, and constitutes the
shapeless mass familiarly known as the _after-birth_, by the retention
of which the most serious trouble is occasionally caused.
Parturition.--At the end of the period of development, the young being
is forcibly expelled from the laboratory of nature in which it has been
formed. In other words, it is born; and this process is termed
_parturition_. Though, at first thought, such an act would seem an utter
impossibility, yet it is a very admirable illustration of nature's
adaptation of means to ends. During the months of gestation, while the
uterus has been enlarging to accommodate its daily increasing contents,
the generative passages have also been increasing in size and becoming
soft and distensible, so that a seeming impossibility is in due time
accomplished without physical damage, though possibly not without
intense suffering. However, it is a most gratifying fact that modern
medical science may do much to mitigate the pains of childbirth. It
is possible, by a proper course of preparation for the expected event,
to greatly lessen the suffering usually undergone; and some ladies
assert that they have thus avoided real pain altogether. Although the
curse pronounced upon the feminine part of the race, in consequence
of the sin of Eve, implies suffering in the parturient act, yet there
is no doubt that the greater share of the daughters of Eve are, through
the perverting and degenerating influences of wrong habits and
especially of modern civilization, compelled to suffer many times more
than their maternal ancestor. We have sufficient evidence of this in
the fact that among barbarian women, who are generally less perverted
physically than civilized women, childbirth is regarded with very
little apprehension, since it occasions little pain or inconvenience.
The same is true of many women among the lower laboring classes. In
short, while it is true that more or less suffering must always
accompany the parturient act, yet the excessive pain usually attendant
upon the process is the result of causes which can in many cases be
removed by proper management beforehand and at the time of confinement.
After being relieved of its contents, the uterus and other organs
rapidly return to nearly their original size.
Changes in the Child at Birth.--In the system of the child a wonderful
change occurs at the moment of its expulsion into the outer world. For
the first time, its lungs are filled with air. For the first time they
receive the full tide of blood. The whole course of the circulation
is changed, and an entirely new process begins. It is surprising in
how short a space of time changes so marvelous can be wrought.
Nursing.--The process of development is not fully complete at birth.
The young life is not yet prepared to support itself; hence, still
further provision is necessary for it. It requires prepared food suited
to its condition. This is provided by the _mammae_, or breasts, of the
female, which are glands for secreting milk. The fully developed gland
is peculiar to the female; but a few instances have been known in which
it has been sufficiently developed to become functionally active in
men, as well as in young girls, though it is usually inactive even in
women until near the close of gestation. It is a curious fact that the
breasts of a new-born child occasionally contain milk.
The first product of the mammae is not the proper milk secretion, but
is a yellowish fluid called _colostrum _. The true milk secretion begins
two or three days after delivery.
The lacteal secretion is influenced in a very remarkable manner by the
mental conditions of the mother. By sudden emotions of grief or anger,
it has been known to undergo such changes as to produce in the child
a fit of indigestion, vomiting, diarrhea, and even convulsions and
death. Any medicine taken by the mother finds its way into the milk,
and often affects the delicate system of the infant more than herself.
This fact should be a warning to those nursing mothers who use
stimulants. Cases are not uncommon in which delicate infants are kept
in a state of intoxication for weeks by the use of alcoholic drinks
by the mother. The popular notion that lager-beer, ale, wine, or alcohol
in any other form, is in any degree necessary or beneficial to a nursing
woman is a great error which cannot be too often noticed and condemned.
Not only is the mother injured, instead of being benefited by such a
practice, but great injury, sometimes life-long in its consequences,
is inflicted upon the babe at her breast who takes the intoxicating
poison at second hand, and is influenced in a fourfold degree from its
feebleness and great susceptibility.
ANATOMY OF THE REPRODUCTIVE ORGANS.
Having now considered the functions and somewhat of the structures of
the principal organs of reproduction, we may obtain a more definite
idea of the relation of the several organs of each class by a connected
review of the anatomy of the parts.
Male Organs.--As previously stated, the external organs of generation
in the male are the _penis_ and the _testicles_, the latter being
contained in a pouch called the _scrotum_. The penis is the organ of
urination as well as copulation. Its structure is cellular, and it
contains a vast number of minute coils of blood-vessels which become
turgid with blood under the influence of sexual excitement, producing
distention and erection of the organ. A canal passes through its entire
length, called the _urethra_, which conveys both the urine and the
seminal fluid. The organ is protected by a loose covering of integument
which folds over the end. This fold is called the _foreskin_ or
_prepuce_.
The fluid formed by each testicle is conveyed by the _vas deferens_,
a curved tube about two feet in length, to the base of the bladder.
Here the vas deferens joins with another duct which communicates with
an elongated pouch, the _vesicula seminalis_, which lies close upon
the under side of the bladder. The single tube thus formed, the
_ejaculatory duct_, conveys the seminal fluid to the urethra, from
which it is discharged.
As the production of seminal fluid is more or less constant in man and
some animals, while its discharge is intermittent, the vesiculae
seminales serve as reservoirs for the fluid, preserving it until
required, or allowing it to undergo absorption. Some claim that the
zoosperms are matured in these organs. They always contain seminal
fluid after the age of puberty. During coition, their contents are
forcibly expelled by a spasmodic contraction of the muscles which
surround them and the ducts leading from them.
The Prostate Gland.--Surrounding the ejaculatory ducts and their
openings into the urethra at the base of the bladder is the _prostate
gland_, which produces a peculiar secretion which forms a considerable
portion of the seminal fluid, being mingled with the secretion of the
testes during its ejaculation. This gland sometimes becomes the seat
of somewhat serious disease. In old age it usually becomes somewhat
indurated, and often to such an extent as to seriously affect the health
and comfort of the individual by interference with urination and by
occasioning pain.
Anterior to this organ, in the urethra, is a curious little pouch, the
_utriculus_, which corresponds to the vagina and uterus in the female.
Just in front of the prostate gland are two small bodies known as
Cowper's glands. They secrete a fluid which combines with the seminal
secretion.
Female Organs.--The _ovaries_, _uterus_, or _womb_, _Fallopian tubes_,
and _vagina_ have already been described in part. The external organs
of the female are included in the term _vulva_ or _pudenda_. The most
superficial parts are the _labia_, two thick folds of integument. Just
within these are two thinner folds, the _labia minora_ or _nymphae_.
These, together with the _clitoris_, situated just above, are extremely
sensitive organs, being the chief seat of sexual sense in the female.
At the lower part is the opening to the vagina, which in the virgin
is usually partially guarded by a thin membrane, the _hymen_. This is
not always a reliable test of virginity, however, as commonly regarded,
since it may be destroyed by disease or accident, and may exist even
after the occurrence of pregnancy.
The vagina extends from the vulva to the lower end of the uterus, which
it incloses, passing between the bladder and the rectum. The lower
extremity of the uterus presents a small opening which leads into its
interior. Upon either side, at its upper and larger end, is a minute
opening, the mouth of the Fallopian tube. The latter organs extend from
the uterus outward nearly to the ovaries, toward which they present
a number of small filaments, one of which is in contact with each ovary.
These filaments, together with the interior of the tubes, are covered
with a peculiar kind of cells, upon which are minute cilia, or hairs,
in constant motion. Very curiously, they all move in the same direction,
toward the cavity of the uterus. When an ovum escapes from the ovary
in connection with menstruation, it is by these delicate hairs
propelled along a filament of tissue to the Fallopian tube, and thence
by the same means is conveyed to the uterus. It may come in contact
with the zoosperms at any point between the ovary and the lower orifice
of the uterus, and thus undergo fecundation.
Puberty.--For a certain period after birth, the sexual organs remain
in a partially developed condition. This period varies in duration with
different animals; in some cases being very brief, in others,
comprising several years. Upon the attainment of a certain age, the
individual becomes sexually perfect, and is then capable of the
generative act. This period is called puberty. In man, puberty commonly
occurs between the ages of ten and fifteen years, varying considerably
in different climates. In this country, and in other countries of about
the same latitude, puberty usually occurs at the age of fourteen or
fourteen and one-half years in females, and a few months later in males.
In cooler climates, as in Norway and Siberia, the change is delayed
to the age of eighteen or nineteen years. In tropical climates it is
hastened, occurring as early as nine or ten years. In warm climates
it is no uncommon thing for a girl to be a mother at twelve; and it
is stated that one of the wives of Mahomet was a mother at ten.