FECUNDATION.
Since in the beginning God created male and female, and said unto them, "Be fruitful, and multiply, and replenish the earth," it is evident that what was originated by creation must be continued by procreation. The process of generation the reader will find described on pages [12] and [13]. Then commences a wonderful series of transforming operations, rudimentary changes preliminary to the formation of tissues, structures and functions, which finally qualify the organism for independent existence. The ovum, when expelled from the ovary, enters the fimbriated, or fringe-like extremity of the Fallopian tube, to commence at once its descent to the uterus. The process of passing through this minute tube varies in different animals. In birds and reptiles, the bulk of the expelled ova is so great as to completely fill up the tube, and it is assisted in its downward course, partly by its own weight and partly by the peristaltic action of the muscular coat of the canal. In the human subject, however, the ova are so minute that nature has supplied a special agent for their direct transmission; otherwise they might be retained, and not reach their destination. Accordingly, the fimbriated, trumpet-shaped extremity of the Fallopian tubes, which is nearest to the ovaries, and, consequently from the ovary first receives the ovum when expelled; is provided with a series of small hairs, termed cilia, forming the lining or basement membrane of the tubes, and, the movements of these cilia being towards the uterus, transmit, by their vibrating motion, the ovum from the ovary, through the Fallopian tubes, to the uterus.
The mature ovum, however, is not by itself capable of being converted into the embryo. It requires fecundation by the spermatic fluid of the male, and this may take place immediately on the expulsion of the ovum from the ovary, or during its passage through the Fallopian tube, or, according to Bischoff, Coste, and others, in the cavity of the uterus, or even upon the surface of the ovary. Should impregnation, however, fail, the ovum gradually loses its vitality, and is eventually expelled by the uterine secretions. It occasionally happens that the descent of the impregnated ovum is arrested, and the formation of the embryo commences in the ovary. This is termed ovarian pregnancy. Or again, the ovum may be arrested in its passage through the Fallopian tube, causing what is termed tubal pregnancy; or, after it has been expelled from the ovary, it may fail to be received by the fimbriated extremity, and escape into the cavity of the abdomen, forming what has been termed ventral pregnancy. If the microscopic germ lodges in some slight interstice of fiber, during its passage through the walls of the uterus, it may be detained long enough to fix itself there, and when this occurs, it is termed interstitial pregnancy. All these instances of extra-uterine pregnancy may necessitate the employment of surgical skill, in order that they may terminate with safety to the mother. Their occurrence, however, is very rare.
The intense nervous excitement produced by the act of coition is immediately followed by a corresponding degree of depression, and a too frequent repetition of it is necessarily injurious to health. The secretions of the seminal fluid being, like other secretions, chiefly under the influence of the nervous system, an expenditure of them requires a corresponding renewal. This renewal greatly taxes the corporeal powers, inducing lassitude, nervousness, and debility. It is a well known fact that the highest degree of mental and bodily vigor is inconsistent with more than a moderate indulgence in sexual intercourse.
To ensure strength, symmetry, and high intellectual culture in the human race, requires considerable care. Consideration should be exercised in the choice of a companion for life. Constitutional as well as hereditary ailments demand our closest attention. Age has also its judicious barriers. As before stated, when reproduction commences, growth, as a rule, ceases, therefore, it is inexpedient that matrimony should be consummated before the parties have arrived at mature stature.