_Lesions._ The enlarged ovary may be uniformly rounded and smooth, or it may be marked by irregular bosses, giving it a lobulated appearance. It is very vascular, and is often covered by a thickening of peritoneum. When multiple they are usually closely adherent and may even be included one within another. The individual cysts may be of the most varied sizes. The cystic ovary has at times reached enormous dimensions: in the mare 46 lbs. (Bouley, Rivolta, Thiernesse): in the cow 250 lbs. (Reynolds, Meyer): in the ewe 7 lbs. (Willis): in the sow 7 lbs. (Reyer): in the bitch 15 lbs. (Bovett). The walls of the cyst are formed of connective tissue more or less perfectly organized, arranged it may be in several superposed layers (Galtier) and lined or not by epithelial cells (cylindroid, nucleated, or of various forms). They may be reddened by hæmorrhages or pigmented from former blood extravasations. The liquid contents may be clear and watery, white, straw yellow, or of a deeper yellow, brown or red. Among other constituents there are alkaline chlorides and sulphates, albumen in solution or flakes, mucin, fibrine, fatty granules and cholesterine crystals. In some instances they contain pus cells (chronic abscess). _Symptoms._ Small, tardily growing cysts may cause no appreciable symptoms. The larger ones or those that increase rapidly are liable to cause disorders of circulation, innervation and digestion. The mere pressure of a considerable cystic ovary may interfere with portal circulation so as to entail muco-enteritis, rectal congestion, piles, or intestinal torpor or impaction. Adhesions of the diseased ovary to adjacent intestinal viscera, tend to produce constrictions, obstructions and local congestions or inflammation. In adhesions to the womb or bladder, ureter or kidney, the symptoms will indicate disorder of these respective parts. The weight of the enlarged ovary causing extension of its ligamentous connections will allow of its winding around a loop of intestine and producing strangulation. In those unusual cases in which pregnancy occurs it may interfere with its completion, causing abortion or, failing in this, with parturition, by becoming imbedded in the pelvis. In the line of innervation, disorder is especially common in the digestive organs, anorexia, nausea, impaired rumination, and colicy pains resulting. Again, in many subjects the genesic instinct is stimulated, the patient is more or less constantly in heat, cows become _bullers_, and mares _switchers_, they cannot be impregnated, and under the continuous excitement undergo rapid emaciation. There is often urinary disturbance, frequent straining with the passage of a small quantity only of turbid or glairy liquid, colored, it may be, by blood, or fœtid. The colics are liable to be dull and slight, the patient moving uneasily, switching the tail, moving the weight from one hind foot to the other, pawing, looking at the flank, but seldom lying down or rolling.