REPRODUCTION.

Reproduction is the function by which the species is preserved, and accomplished by the organs of generation in the two sexes.

GENERATIVE ORGANS OF THE FEMALE.

The Generative Organs of the Female consist of the ovaries, Fallopian tubes, uterus, and vagina.

The Ovaries are two small, ovoid, flattened bodies, measuring one inch and a half in length and three-quarters of an inch in width; they are situated in the cavity of the pelvis, and imbedded in the posterior layer of the broad ligament; attached to the uterus by a round ligament, and to the extremities of the Fallopian tubes by the fimbriæ. The ovary consists of an external membrane of fibrous tissue, the cortical portion, in which are imbedded the Graafian vesicles, and an internal portion, the stroma, containing blood-vessels.

The Graafian Vesicles are exceedingly numerous, but situated only in the cortical portion. Although the ovary contains the vesicles from the period of birth, it is only at the period of puberty that they attain their full development. From this time onward to the catamenial period there is a constant growth and maturation of the Graafian vesicles. They consist of an external investment, composed of fibrous tissue and blood-vessels, in the interior of which is a layer of cells forming the membrana granulosa; at its lower portion there is an accumulation of cells, the proligerous disc, in which the ovum is contained. The cavity of the vesicle contains a slightly yellowish, alkaline, albuminous fluid.

The Ovum is a globular body, measuring about the 15 of an inch in diameter; it consists of an external investing membrane, the vitelline membrane; a central granular substance, the vitellus or yelk; a nucleus, the germinal vesicle, in the interior of which is imbedded the nucleolus, or germinal spot.

The Fallopian Tubes are about four inches in length, and extend outward from the upper angles of the uterus, between the folds of the broad ligaments, and terminate in a fringed extremity which is attached by one of the fringes to the ovary. They consist of three coats: (1) the external, or

peritoneal, (2) middle, or muscular, the fibers of which are arranged in a circular or longitudinal direction, (3) internal, or mucous, covered with ciliated epithelial cells, which are always waving from the ovary toward the uterus.

The Uterus is pyriform in shape, and may be divided into a body and neck; it measures about three inches in length and two inches in breadth in the unimpregnated state. At the lower extremity of the neck is the os externum; at the junction of the neck with the body is a constriction, the os internum. The cavity of the uterus is triangular in shape, the walls of which are almost in contact.

The walls of the uterus are made up of several layers of non-striated muscular fibers, covered externally by peritoneum, and lined internally by mucous membrane, containing numerous tubular glands, and covered by ciliated epithelial cells.

The Vagina is a membranous canal, from five to six inches in length, situated between the rectum and bladder. It extends obliquely upward from the surface, almost to the brim of the pelvis, and embraces at its upper extremity the neck of the uterus.

Discharge of the Ovum.-As the Graafian vesicle matures, it increases in size, from an augmentation of its liquid contents, and approaches the surface of the ovary, where it forms a projection, measuring from onefourth to one-half an inch in size. The maturation of the vesicle occurs periodically, about every twenty-eight days, and is attended by the phenomena of menstruation. During this period of active congestion of the reproductive organs, the Graafian vesicle ruptures, the ovum and liquid contents escape, and are caught by the fimbriated extremity of the Fallopian tube, which has adapted itself to the posterior surface of the ovary. The passage of the ovum through the Fallopian tube into the uterus occupies from ten to fourteen days, and is accomplished by muscular contraction and the action of the ciliated epithelium.

Menstruation is a periodical discharge of blood from the mucous membrane of the uterus, due to a fatty degeneration of the small blood-vessels. Under the pressure of an increased amount of blood in the reproductive organs, attending the process of ovulation, the blood-vessels rupture, and a hemorrhage takes place into the uterine cavity; thence it passes into the vagina. Menstruation lasts from five to six days, and the amount of blood discharged averages about five ounces.

Corpus Luteum.-For some time anterior to the rupture of a Graafian vesicle, it increases in size and becomes vascular; its walls become thick