532

fold receives the combined vesicular and seminal ducts, g, g. A small style passed into it, as at f, penetrates a pyriform sac in the middle lobe of the prostate, which is the remnant of the protometra: it is exposed by removal of the glandular covering, at e, fig. 533. Cowper's glands are rounded bodies, about the size of an ordinary pea; of a solid texture, a palish red colour, and conglomerate. The lobules are connected together by areolar tissue, and are surrounded by a fibrous capsule: they are composed of elongate follicles, from the fiftieth to the twenty-fifth of a line in length, and about the thirty-sixth of a line in breadth. Their slender ducts, of about the eighteenth or sixteenth of a line in diameter, usually coalesce into a single excretory duct. The ducts of each gland run parallel for the distance

of half an inch beneath the mucous membrane of the bulb, and approaching each other, they pierce the urethra by two exceedingly minute orifices.

The penis consists of the erectile tissues called ' corpora cavernosa' and 'corpus spongiosum,' the latter inclosing the urethra and expanding at its hind end into the bulb' and at its fore end into the glans.' The 6 corpus cavernosum' forms in Man more than two-thirds of the bulk of the penis: it is a lengthened subdepressed cylinder, with a median groove both above and below; the upper groove lodging the dorsal vein, arteries, and nerves, and the under one the corpus spongiosum. Anteriorly the corpus cavernosum terminates in an oblong and rounded extremity, which is received into a depres

Verumontanum, Man.

533

A

Vesicular and prostatic glands, with protometra, Human; half nat, size. CCLXVIII".

sion on the posterior surface of the glans; posteriorly it is attached to the ischiopubic rami by its two crura; and above it

is connected to the symphysis pubis by means of a strong triangular fascia, the ligamentum suspensorium penis.'

6

The corpus cavernosum' is composed of a cellular structure enclosed in a strong sclerous tunic, from the inner surface of which are given off numerous bands, trabeculæ,' which converge towards the middle line of the inferior wall; they are most abundant in the middle line of the organ, where they form a septum between the two lateral halves of the corpus cavernosum: but this becomes incomplete or pectinate' anteriorly. The so-called cellular structure of the corpus cavernosum consists of a plexus of dilated and freely intercommunicating veins, the interspaces of which are occupied by contractile tissue: the fibres being unstriped and with a general arrangement transversely to the axis of the penis.

Besides the erectores penis' and acceleratores urinæ,' there is a remnant of the levatores penis' reduced to the function of compressores venæ dorsalis;' and occasionally a small fan-shaped muscle, ischio-bulbosus,' may be defined in the interspace between the bulb and crura penis, having a slender attachment to each ischium, and expanding upon the bulb. The prepuce is connected to the glans on its under part by means of a narrow fold, with some sclerous tissue, termed the 'frænum præputii.' At the base of the prepuce, where it is reflected over the glans, open the small lenticular representatives, called 'glandulæ odoriferæ,' of the preputial follicles of lower Mammals.

534

B. FEMALE ORGANS OF MAMMALS.

6

The ovaries retain, as in lower Vertebrates, their abdominal position; but are relatively small in Mammalia, and consist of a dense areolar 'stroma,' which, with the ovisacs therein developed, is inclosed in a firm sclerous 'tunica albuginea,' fig. 534, a. The abdominal aperture of the oviduct is wide, and, as a rule, fimbriate;' but the canal quickly eontracts, usually to a diameter like that of the spermduct, and, after a certain course, suddenly expands, or opens, into a 'uterus.' This may remain distinct from its fellow; but a prevalent mammalian characteristic is a blending of the uteri, to terminate by one valvular orifice in a vagina;' the confluence extending, by degrees, in different species, until a single uterus results. The vagina, as a rule, is single, and usually

Section of Human Ovarium; nat. size.
COXLVI".

terminates by a ' vulva' distinct from the vent. The clitoris' is single. The variations in the efferent and subordinate parts of the female organs are greater and more numerous in Mammals than in other Vertebrates, and with female sexual organs are associated functional mammary glands: marsupial pouches are superadded in most Lyencephala.

§ 382. In Monotremata.-The female organs here consist of two ovaria, the right much smaller than the left, two oviducts, two uteri, an urogenital passage, and a clitoris.

The ovaria correspond in situation and surrounding attachments with the testes in the male; and the oviducts and uteri exhibit in their closely convoluted disposition an analogy with the spermducts.

The left ovary, fig. 535, f, is an irregular, semi-elliptical, flattened body, with a wrinkled and granulate surface in the unexcited state; but becomes thicker, with the surface studded by elevations formed by the ovisacs in different stages of development, at the season of sexual excitement. At this period usually two ovisacs, as in the figure, are conspicuously larger than the rest, and present each a diameter of about two lines. The right ovary, ƒ, is a narrow, thin, generally elongated body; sometimes broader, with a finely granulated surface. It is often scarcely to be distinguished from the ovarian ligament to which it is attached. This ligament, i, i, arises from the posterior parietes of the abdomen, behind and a little on the outer side of the kidney, and passes along the edge of the broad ligament to the fallopian extremity of the oviduct, where it divides into two; one portion is attached to the side of the ovary, the other to the posterior margin of the fallopian orifice: after a course of an inch they again unite, and the ligament is continued along the anterior part of the uterus to its cervix, where it is insensibly lost. The two separated portions of the ligament support a large pouch of peritoneum, which forms the ovarian capsule; the wide anterior orifice of the oviduct is also, by means of this ligament, prevented from being drawn away from the from the ovary.

The efferent canal of the ovarian products is divisible into an oviduct or fallopian tube, d', and an uterus, d. The size of the latter is nearly equal on both sides, but the right oviduct is much shorter than the left, and corresponds with the abortive condition of the ovary. The external serous coat of the oviduct is loosely connected to the muscular coat by filamentary processes of areolar The mustissue, among which numerous tortuous vessels ramify. cular coat is thin and compact, and is most readily demonstrable

in the uterus. The mucous coat is thin and smooth in the oviduct; it is thick, soft, plicated, but not villous, in the uterus. The left uterus in a female with a large ovary, shot in the month of September, was two inches long, from four to five lines in diameter, and about a line thick in its parietes; it became suddenly contracted and thinner in its coats to form the oviduct, which presented a diameter of about two lines, slightly enlarging to within an inch of the extremity, which forms a wide membranous pouch, d' opening into the capsule of the ovary by an oblong orifice or slit, e, of eight lines in extent. The edges of this orifice were entire as in the oviducts of Reptiles, not indented as in the fimbriated extremity of the Fallopian tube in higher Mammals. The entire length of the oviduct and uterine tube, when detached from their connections with the mesometry, was nine inches. The right uterus and oviduct of the same specimen exhibited similar differences in diameter and structure, but was shorter, measuring only six inches in length.

The thickened parietes of the uterine tube depends chiefly on an increase of the inner membrane, which, at the cervix uteri, presents deep and close-set furrows: these, as the canal widens, are gradually lost, and the surface becomes more or less smooth. In the oviduct, the inner surface is smooth on leaving the uterus, then becomes finely reticulate, and in the terminal dilated part becomes again smooth. The cervix uteri makes a valvular projection analogous to an os tincæ on each side of the commencement of the urogenital canal, just beyond the orifice of the urinary bladder. There are two orifices on each of these prominences: the lower one is the termination of the ureter-a bristle is represented as passing through it in fig. 535; the upper or anterior orifice is the os uteri, m. In young or virgin Ornithorhynchi this orifice forms scarcely any projection into the urogenital canal, and it is divided by a narrow septum. The urogenital canal, c, is one inch and a half long, and three or four lines in diameter, but capable of being dilated to as great an extent probably as the pelvis will admit of; the diameter of the bony passage being seven-tenths of an inch. It is invested with a muscular coat, the external fibres of which are longitudinal; the internal, circular. The inner membrane of this part is disposed in longitudinal rugæ more or less marked, but presents as little the character of a secreting membrane as that of the vestibule, being smooth and shining; the orifices of a few minute follicles are situated in the interstices of the rugæ near the orifice of the urinary bladder.