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walls are dense, and its canal is extremely small. At the fundus of the bladder it becomes enlarged and tortuous, and this portion is termed the ampulla. A small triangular area of the fundus of the bladder, between the ductus deferentes laterally and the bottom of the rectovesical excavation of peritoneum above, is in contact with the rectum.

Ductuli Aberrantes.

—A long narrow tube, the ductulus aberrans inferior (vas aberrans of Haller), is occasionally found connected with the lower part of the canal of the epididymis, or with the commencement of the ductus deferens. Its length varies from 3.5 to 35 cm., and it may become dilated toward its extremity; more commonly it retains the same diameter throughout. Its structure is similar to that of the ductus deferens. Occasionally it is found unconnected with the epididymis. A second tube, the ductulus aberrans superior, occurs in the head of the epididymis; it is connected with the rete testis.

Paradidymis (organ of Giraldés).—This term is applied to a small collection of convoluted tubules, situated in front of the lower part of the cord above the head of the epididymis. These tubes are lined with columnar ciliated epithelium, and probably represent the remains of a part of the Wolffian body.

Structure.

—The ductus deferens consists of three coats: (1) an external or areolar coat; (2) a muscular coat which in the greater part of the tube consists of two layers of unstriped muscular fiber: an outer, longitudinal in direction, and an inner, circular; but in addition to these, at the commencement of the ductus, there is a third layer, consisting of longitudinal fibers, placed internal to the circular stratum, between it and the mucous membrane; (3) an internal or mucous coat, which is pale, and arranged in longitudinal folds. The mucous coat is lined by columnar epithelium which is non-ciliated throughout the greater part of the tube; a variable portion of the testicular end of the tube is lined by two strata of columnar cells and the cells of the superficial layer are ciliated.

FIG. 1152– Fundus of the bladder with the vesiculæ seminales. (See enlarged image)

3c. 3. The Vesiculæ Seminales

(Seminal Vesicales)

The vesiculæ seminales (Fig. 1152) are two lobulated membranous pouches, placed between the fundus of the bladder and the rectum, serving as reservoirs for the semen, and secreting a fluid to be added to the secretion of the testes. Each sac is somewhat pyramidal in form, the broad end being directed backward, upward and lateralward. It is usually about 7.5 cm. long, but varies in size, not only in different individuals, but also in the same individual on the two sides. The anterior surface is in contact with the fundus of the bladder, extending from near the termination of the ureter

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