Tuberculosis may affect the ovaries and cause permanent sterility. In inflammation of the lining membrane of the womb and vagina, the secretions are abnormal and may collect in the womb and the passages leading to it. These secretions destroy the vitality of the spermatozoa, and this condition may be considered a common cause of sterility in the larger animals. Many vigorous young males are made impotent by excessive copulation. The excessive use of the male at any time may result in failure to impregnate a large percentage of the females that he serves. Barren females do not become pregnant after frequent intercourse with the male. Young sterile females may not come in heat. Sometimes unnatural periods of heat are manifested, the animal coming in heat frequently or remaining in heat for a longer period than usual. This sometimes occurs in tuberculosis of the ovaries. In chronic inflammation of the maternal passage there is more or less discharge from the vulva. Both sexes may be overly fat or weakened and debilitated by disease. Deformity of the generative organs and growths may be found on making an examination. Absence of, or lack of vitality of the spermatozoa may be determined by microscopic examination of the seminal fluid. _The treatment_ is largely preventive. It is very important that breeding animals be kept in proper physical condition by avoiding the feeding of too heavy or too light a ration, and allowing them sufficient exercise. The male is more often affected by the latter cause than the female. This is because the average stockman does not consider exercise given under the right conditions an important factor in maintaining the vigor of the male. Young males should not be given excessive intercourse with the female. Such practice is certain to seriously affect the potency of the animal. The excessive use of the stallion can be avoided by practising artificial impregnation of a part of the mares that he is called to serve. Sterility caused by growths and closure of the os may be corrected by an operation. Chronic inflammation of the maternal passages should be treated by irrigating the parts with a one per cent warm water solution of lysol, or liquor cresolis compound. The parts should be irrigated daily for as long a period as necessary. Fat animals should be subjected to a rigid diet and given plenty of exercise. Following this treatment a stimulating ration may be fed for the purpose of encouraging the sexual desire. In weak and debilitated animals, the cause should first be removed and a proper ration fed. Cantharides and strychnine are the drugs most highly recommended for increasing the sexual desire.