What a Young Husband Ought to Know

by Sylvanus Stall

Between these two blastodermic membranes other minute tissues are formed, the office and end of which are not so fully understood, and the consideration of which would lead us into intricacies beyond our present purpose.

The first visible sign of the organic structure of the human form is discovered as it takes shape upon the exterior wall of the blastodermic membrane, known as the embryonic spot, and known also as the primitive trace or furrow. It is supposed that from this is formed the spinal canal, with the dorsal plate upon either side, from which springs the framework of the bony structure, and at one end of which is the large rounded cavity which forms the receptacle for the brain and the medulla oblongata, or the upper cranial portion of the spinal cord, which is to control respiration, and at the other extremity of which, in a later stage, will sprout or grow the legs and feet.

Without complicating the subject too much for the clear understanding of the ordinary reader by undertaking to explain minute changes which are very interesting to specialists, but likely to detract from its interest and value to the ordinary reader, let it suffice to say that in the course of a brief period the embryo which has grown mainly from the two blastodermic membranes which we have described, and is attached to the walls of the womb by the placenta and cord which carries the blood and life-currents from the body of the mother to the growing body of the child within, is at this period of its development surrounded and enclosed by a number of membranes. The outer one of these is the inner lining of the womb itself, known as the decidua vera. Within this is the decidua reflex, the membrane of the womb, which extended itself and grew around the ovum, completely enclosing it. The third is the chorion, forming the outer membrane which encloses the fetus, and within which is the amnion, or innermost membrane which surrounds the fetus, and between which is another membrane, called the allantois.

The amnion, which is the innermost of the membranes surrounding the fetus, seemingly has a special office, which is to secrete the fluid technically called the amniotic. This fluid is popularly known as "the waters." This secretion performs several important offices. It protects the fetus from any local pressure or blow, and so distributes any pressure as to enable all the parts to grow without danger of distortion and deformity. It also affords the fetus greater freedom of motion, and protects the womb and other parts from injuries which might otherwise be inflicted by the fetus after quickening. Within this fluid the fetus floats during its formative period, and when the time of birth comes the breaking of the sac which contains this fluid enables it to flow out, lubricating the parts, or channel, through which the newly formed being is to pass in its exit into the outer world. The importance of this fluid in this latter office is of great moment. When the sac breaks and the waters flow away too much in advance of the birth of the child, there generally occur the inconveniences that attend what is called a "dry birth."

As already mentioned in a previous paragraph, during the first weeks of growth the embryo is nourished the same as the young chick within the egg, by the yolk, in which its earliest nourishment has been stored.

Soon the delicate union is formed between the chorion by the gathering and multiplication of the villi or minute hair-like membranes, which gather into a compact mass and adhere to the adjacent portion of the womb. This formation is known as the placenta, previously described, which is constituted of two portions—the maternal side, which is toward the walls of the womb, and the fetal side, which is toward the growing fetus. Upon the inner side, the placenta is united with the fetus by two arteries which are wrapped around the one vein, which together unite with the body of the placenta. Through these the life-currents flow; and, while the circulation between the bodies of mother and child are not direct or uninterrupted, for the fetus has its own measurably independent circulation, yet from the time the connection is formed until the cord is severed at birth the fetus derives all its nourishment from the mother.

Let us turn now to note the rapid changes which take place within the germ or egg from the time of its impregnation to the hour of the birth of the child. The changes, although seemingly very minute at first, are nevertheless very rapid from the beginning to the period of maturity and birth. The following account, taken from "Plain Talks on Avoided Subjects," by Henry N. Guernsey, M.D., constitutes a goodly portion of the introductory chapter of that excellent little book, and presents the matter in the intelligible and impressive manner we desire for this place, and is quoted in full by permission:

"The first indication of formation that is possible to discover, even by the help of the microscope, consists of an oblong figure, obtuse at one extremity, swollen in the middle, blunt-pointed at the other extremity. The rudimentary embryo is slightly curved forward, is of a grayish-white color, of a gelatinous consistence, from two to four lines long, and weighs one or two grains. A slight depression, representing the neck, enables us to distinguish the head; the body is marked by a swollen centre, but there are as yet no traces of the extremities. So much can be observed about the end of the third week after conception.

"At about the fifth week the embryo presents more distinctions. The head is very large in proportion to the rest of the body, the eyes are represented by two black spots, and the upper extremities by small protuberances on the sides of the trunk. The embryo at this stage is nearly two-thirds of an inch in length and weighs about fifteen grains. The lower extremities now begin to appear in the shape of two minute rounded tubercles. Till about this time a straight artery has been observed to beat with the regularity of the pulse; but now it appears doubled somewhat into the shape of an adult heart, although as yet it has but one auricle and one ventricle. As time advances we find the perfect heart, with its two ventricles and two auricles, all developed from the original straight artery. At this period the lungs appear to exist in five or six different lobes, and we can barely distinguish the bronchial tubes; about the same time the ears and face are distinctly outlined, and after awhile the nose is also faintly and imperfectly perceived.

"At about the seventh week, little bony deposit is found in the lower jaw. The kidneys now begin to be formed, and a little later the genital organs. The embryo averages one inch in length.