One bull in the department herd certainly had a severe ordeal as a calf, but as a mature bull he was highly fertile. Moderate sexual use and proper sexual hygiene probably had much to do with this. In the bull, infection of some part of the genitals, during some period of life, is very constant, however, whether or not it is productive of observable changes in his breeding efficiency. The finding of the fine connective tissue strands and tufts on the serous surface of the tail of the epididymis of practically all bulls examined, both sterile and fertile, indicates past or present infection of the scrotal sac. The vesicles and tail of the epididymis are, as stated previously, the most commonly invaded tissues of the tract. The testes are less frequently involved. While it is difficult to obtain irreproachable proof that the bull is a disseminator of genital infections, the findings of clinicians quite clearly indicate that this is true, and laboratory methods tend to support this assumption. Williams believes that not only may the bull infect the female with organisms which interfere with the given conception, but that he often implants there organisms which interfere with future pregnancies, and even with the life of the individual in some cases. The high abortion and sterility rate following the use of certain sires, and the appearance of characteristic infections after service to certain bulls, clearly indicate that in all probability the bull does eliminate with his semen those organisms which produce lesions in his genital organs, and are capable of infecting the female. W. L. Williams (48) cites the case of a pure bred herd in which breeding had progressed satisfactorily until heifers had grown to breeding age and a second bull was obtained. “Some cows of the old herd were also assigned to the young bull which had not previously been in service. The cows bred to the old herd bull continued to breed normally. The cows and heifer’s bred to the new bull conceived with difficulty or not at all. Those which conceived mostly aborted, and those which calved had metritis and retained fetal membranes. The two first cows in which pregnancy terminated died of metritis.” I have frequently had semen samples sent in from bulls that were not only failing to get cows with calf, but following each service the females showed a severe vaginitis. W. W. Williams worked in a herd in which service to certain bulls was in each case followed by a severe vaginitis and cervicitis, only to be followed later by a characteristic salpingitis.