Zannger, in 1860, introduced the method of rupturing the cyst without incision, and met with considerable success. With the hand in the rectum the cystic ovary is pressed against the wall of the pelvis or abdomen, until the attenuated wall of the cyst gives way, the fluid is left in the abdominal cavity, to be absorbed and many animals will afterward become pregnant. In a large proportion of cases in which the symptoms are marked, the walls of the cyst are sufficiently attenuated to allow of rupture by pressure, and, if the escaping contents are free from infecting microbes, no immediate harm comes to the peritoneum. It should be avoided in case of abscess, following perhaps on a shivering fit and constitutional febrile reaction, and when there is a fœtid discharge from the vulva, suggesting microbian infection likely to dangerously infect the serosa. In appropriate cases it is a resort of very great value, in restoring to use animals that are especially valuable for their progeny and which become utterly useless when rendered barren. According to different observers an average of 70 per cent. can be restored to usefulness in this way. Friedberger and Fröhner claim 90 per cent. Some febrile reaction may be noted for twenty-four hours, demanding rest, restricted, cooling, laxative food and sometimes laxatives and anodynes. DERMOID CYSTS OF THE OVARY. PILOUS CYSTS. Closed cutaneous sacs, with hair and sebum. Causes: enclosure of dermoid tissue in embryo: aborted ovum: virgin gestation. Symptoms. Treatment: Castration. These are much less common than are simple cysts. They are closed sacs, lined by a tissue essentially representing skin, and containing sebaceous matter and hairs, some growing from the dermoid surface, and others detached and formed into a loose mass. _Causes._ These cysts have been attributed to the enclosure, in the forming embryo, of the formative elements of dermoid tissue, which may or may not remain latent and inactive until maturity, or until the ovary becomes physiologically active. Another theory is that an impregnated ovum has remained imperfect, developing only the elements of the skin, instead of the whole fœtal body. Many cases cannot by any possibility be included under this head, seeing that the cyst is found at much too early an age, and its bearer has never had sexual intercourse. Another doctrine is that the dermoid cyst is derived from the normal plastic or formative powers of the ovary, and the product becomes suggestive of parthenogenesis or virgin gestation. The fact that these cysts are not confined to the production of skin and hair, but at times form bone, teeth, nervous and other tissues as well, corroborates this view. On the other hand we must bear in mind that dermoid cysts are much more common in other tissues than they are in the ovaries. Thus they are common in the subcutaneous connective tissue and between the muscles.