In olden times authors, just as the laity often do yet, comprised the whole parturient canal under the term "womb" or uterus. Now the profession has learned to distinguish the womb from the vagina, but the latter is yet in obstetrical and gynecological language frequently confounded with the vulva. We must, therefore, expressly call attention to the limits between these two parts of the parturient canal, and the difference between the two openings at its beginning. The entrance to the vulva is formed by the rima pudendi, a slit in the skin running in a straight line, in an antero-posterior direction; the entrance to the vagina lies an inch or two deeper, is circular, surrounded by mucous membrane and muscles, and is marked by the hymen or its remnants.

FIG. 35.

Horizontal Section of the Soft Parts in the Inferior Strait of the Pelvis (Henle): Va, vagina; Ur, urethra ; R, rectum; L, levator ani.

The size of the vagina varies enormously in different individuals and different conditions. In the adult virgin the anterior wall is about 2 inches, the posterior about 2 inches long, and the width near the upper end about 13 inches. By coition, and especially childbirth, these dimensions are much increased. During copulation it has the size of the body that distends it. During pregnancy great proliferation of tissue, swelling of veins, and serous infiltration take place, so that at the time of delivery the canal not only is wide enough to let the child pass, but becomes so elongated that it can accompany the child far beyond the limits of the outlet of the bony pelvis. The vagina is composed (Figs. 36, 37) of an outer sheath of connective tissue, containing fat, a muscular layer with longitudinal and transverse fibres, and a mucous membrane with flat epithelium. The muscular fibres can be followed to the posterior surface of the pubic bone and the anterior surface of the sacro-iliac articulation (Rouget). In the perineal region the muscle-fibres reach the bone between the two layers of the triangular ligament. The mucous membrane forms on the anterior wall a longitudinal ridge in or near the median line, from which folds, so-called ruga, go out to the sides, like the teeth of a comb; a similar but less distinct formation is found on the posterior wall. They are called the anterior and posterior columns. The anterior often ends below in a round protuberance, called the tubercle of the vagina, which is situated immediately behind the meatus urinarius. Often the anterior column is divided by a lon

gitudinal furrow into two halves. The rugæ are covered with microscopical papillæ. The columns and the rugæ disappear in the upper part of the vagina. They are organs of sexual excitement, and con

FIG. 36.-Longitudinal Section of the Posterior Wall of the Vagina of a girl twenty-four years old. FIG. 37.-Transverse Section of the Same (Breisky): a, mucous membrane; b, muscular layer, with a, circular, and ß, longitudinal fibres; c, fibrous layer containing adipose tissue.

tribute probably to the enlargement of the vagina during pregnancy and childbirth. After the latter they are much less prominent or disappear entirely. The presence of glands in the mucous membrane is disputed.' The vagina possesses the power of absorption. This faculty is increased in pregnant, puerperal, and feverish women."

The vagina has a rich vascular supply. The arteries (Fig. 38) come from the vaginal, the uterine, the vesical, and the internal pudic, which all are branches of the anterior division of the internal iliac.

1 In a woman in the fifth month of pregnancy I have seen the whole vagina red and full of openings like a tonsil, out of which a solid yellowish discharge could be pressed. I do not see what these openings could have been except entrances to glandular follicles.

2 Coen and Levi: Centralblatt für Gynäkologie, 1894, No. 49, p. 1261.

FIG. 38.-The Arteries of the Uterus, the Ovaries, and the Vagina (Hyrtl): 04, ovarian artery, a', b, and c, branches to tube; b, branch to round ligament; c', branches to the ovary; d, anastomosis between ovarian and uterine artery; LA and e, uterine artery; f, vaginal artery; g, branches of vaginal artery; h, azygos artery of vagina. In the drawing the vaginal artery is larger than the uterine, which is unusual. A branch of the uterine artery goes to the cervix, anastomosing with that of the other side (circular artery and with the vaginal arteries. The organs are represented in normal size, but in order to show the arteries well they have been injected after the removal of the specimen from the body and after stretching the tube and the broad ligament. Thus the distance from the median line to the fimbriated end of the tube has become about twice the distance from the median line to the wall of the pelvis.