_Prostate._—The prostate is a gland, chestnut-like in shape. Its greatest diameter is in average about 4 centimeters. The diameter from the base to the apex is about 3 centimeters. The thickness of the prostate is about 2 centimeters, and its weight is about 18 grammes. The upper broad margin, the basis, is adjacent to the bladder, the lower, narrower end, or the apex, rests on the diaphragma urogenitale. It thus lies completely within the abdominal cavity. The anterior surface is connected with the lower end of the symphysis pubis by the ligamenta puboprostatica, the posterior surface is connected with the rectum by loose connective tissue. The prostate is lobulated and generally divided into three lobes, a median and two lateral lobes. The prostate embraces the neck of the bladder and the first portion of the urethra. The structure of the prostate is a framework of muscular fibres, in which are embedded numerous racemous glands. The latter collect and open into the prostatic ducts. The main substance of the prostate is glandular. The mucous lining of the prostate, which forms at the same time the mucous membrane of the prostatic urethra, shows upon the posterior wall a linear elevation of the mucous membrane which covers a fold of erectile tissue, the so-called colliculus seminalis. [Illustration: CUT X. _Colliculus_ 1, orifice of the sinus pocularis; 2, orifices of the prostatic ducts.] _Colliculus._—The colliculus is a massive button, 3 millimeters in height and in breadth, and lies anteriorly to the fossa prostatica. On the summit of the colliculus there is an opening which leads to a pear-shaped pouch, the so-called sinus pocularis, a remnant of the Müllerian ducts. The two orifices of the ejaculatory ducts are found within the pouch, near its opening into the urethra. The orifices of the prostatic ducts are situated in the furrows, on either side of the colliculus. In the state of erection the colliculus fills out the urethra completely and closes it up tightly and absolutely, so that not a drop of urine can pass out of the bladder or escape during ejaculation. _Cowper’s glands._—Cowper’s glands are two acinose glands of the size of a pea. They are embedded between the muscular fibres of the musculus transversus perinei profundus. The ducts run between the two leaflets of the diaphragma urogenitale to the posterior end of the bulbus, hence within the cavernous tissue near the septum and open on either side of the bulbus on the floor of the bulbous urethra. [Illustration: CUT XI. _Crosscut through the penis._ 1, vena dorsalis; 2, arteriæ dorsales; 3, septum; 4, corpora cavernosa; 5, tunica albuginea; 6, vena profunda; 7, urethra; 8, corpus cavernosum urethræ.]