=Hydrocele.= _Simple Hydrocele_ is a dropsy of the tunica vaginalis. The fluid is usually clear, and of a straw color, sometimes turbid, with albuminous flocculi, and not unfrequently contains shining particles of cholesterine. In old or very large hydrocele, it is often dark-brown or chocolate colored from disintegrated blood. Its quantity is sometimes very considerable. The position of the testicle may be altered by adhesions formed between the two layers of the tunica vaginalis; these latter may also produce a multilocular hydrocele. Simple hydrocele may occur with some of the other varieties to be mentioned, and also with inguinal hernia. When serous effusion in the tunica vaginalis, is associated with chronic orchitis or other diseases of the gland, we have _hydro-sarcocele_. In _congenital hydrocele_, the dropsical tunica vaginalis retains its fœtal communication with the peritoneal cavity. _Encysted Hydrocele._ In this variety the fluid is contained in cysts, which may be situated (1) beneath the visceral portion of the tunica vaginalis, investing the epididymis; (2) between the testicular portion of the tunica vaginalis and the tunica albuginea, which are thus separated from each other; (3) between the layers of the loose or reflected portion of the tunica vaginalis. The two last mentioned varieties are of rare occurrence. The cysts have thin fibrous walls, a lining of tessellated epithelium, and contents usually clear, although sometimes mixed with various exudations of fibrin or even blood. Spermatozoa are very frequently found in the fluid of these cysts. Their presence is undoubtedly due, as pointed out by Cushing, to the rupture of a neighboring seminal duct. They are but rarely found in the fluid of common hydrocele. _Diffused Hydrocele of the Cord_, gives rise to an oval or oblong, irregular, circumscribed tumor, extending below and into the inguinal canal. “It consists in the enlargement of the cells of the areolar tissue, and their distension with a white or yellowish serous fluid. The inclosing fascial sheath is condensed and thickened, and at the lower part of the swelling, which is always the largest, separates it completely from the tunica vaginalis.” _Encysted Hydrocele of the Cord_ forms a tumor of oval shape, loosely attached to the vessels of the cord which pass behind it. Instead of a single cyst, there may be a number, forming a series along the cord. =Hæmatocele=, is a tumor formed by an effusion of blood from the vessels of the testis or of the spermatic cord, into the cavity of the tunica vaginalis. It may be traumatic or spontaneous, and may attain a large size. Coagula are formed either in separate masses, or in firm layers, as in aneurism. Inflammation may be set up, leading to fibrinous and serous effusion, and to suppuration, or the blood may putrify and gangrene result. The tunica vaginalis is commonly thickened, the testicle unaffected, or in old cases atrophied from pressure.