Ovarian hydrocele has a different origin. To understand it a brief reference to the relation between the ovary and the broad ligament is necessary. I quote from Bland Sutton: “The ovary projects from, and is invested by the posterior layer of the broad ligament. When the parts are examined _in situ_, the ovary will be found to lie in or upon the edge of a shallow recess in the mesosalpinx. This recess is the ovarian sac (Fig. 163). It varies in depth; in many it is small and inconspicuous, whilst in others it is sufficiently deep to accommodate the entire ovary. In the virgin the ampulla of the tube falls over the mouth of this recess and conceals the ovary. This relation of parts is usually disturbed in the first pregnancy.” [Illustration: FIG. 163.--Left Fallopian tube from an adult (after Richard).] Tait[1] says: “In a few exceptions I have seen a crescentic double fold of the posterior layer of the broad ligament pass down behind the ovary, covering it like the hood of a ‘Nepenthes’ gland. In all such cases the women have been sterile, probably because this hood has prevented the application to the ovary of the opening of the oviduct. I have seen this arrangement give great trouble in the removal of small ovaries.” In some animals the ovarian sac is much better developed than in the human female. In the hyena it forms a complete tunic to the ovary, the cavity of the sac communicating with the peritoneum by a small opening. In rats and mice the sac is complete, and the Fallopian tube communicates with the ovarian sac, but not with the general peritoneal cavity. Ovarian hydrocele occurs in women when the abdominal ostium of the Fallopian tube opens into a well-formed ovarian sac and the common cavity becomes distended with fluid. Sutton sums up the peculiarities of ovarian hydrocele as follows: I. The Fallopian tube opens by its abdominal ostium into a sac on the posterior aspect of the broad ligament. II. The tube is elongated, dilated, and tortuous, resembling a retort with a convoluted delivery tube. III. As a rule, there is no evidence of inflammation. The cyst may suppurate should the tube become affected with salpingitis. IV. In small cysts the ovary will be found projecting on the floor of the sac. In larger specimens it will be incorporated with the wall of the sac, and in very large specimens it is unrecognizable. An ovarian hydrocele may attain considerable size. A case has been reported in which three pints of straw-colored fluid were found in the cyst. An ovarian hydrocele is sometimes intermitting, discharging its contents through the tube into the uterus. The _symptoms_ of ovarian hydrocele resemble those of a small ovarian cyst or a tubo-ovarian cyst. The _treatment_ is celiotomy and removal of the tube and ovary, or, when practicable, the liberation of the adherent end of the Fallopian tube. CHAPTER XXIX. CYSTIC TUMORS OF THE OVARY.