Of the sixteen bulls in Group III, slaughtered at abattoirs, and in which no history was available, eight failed to show the presence of any organisms in their genitalia. Of the others, the vesicles yielded cultures of Staphylococcus albus nine times, and streptococci four times. Staphylococcus albus was recovered once from the prostate, and once from Cowper’s glands. The testes gave cultures of staphylococci in two cases, and Bact. abortum in one. No observable anatomical changes accompanied the presence of the Bang bacillus in this case. The epididymes showed growths of staphylococci five times, and streptococci on three occasions. Streptococci were isolated from the scrotal sacs of eight testes.

The results in Group IV (aborted fetuses) show that bacteria are often present in the seminal vesicles or testes of these animals. As a rule, however, the organisms are identical with those isolated from the blood or other parts of the animal. This is to be expected, however, for because of the feeble resistance of the fetus to any infection, the organisms circulating in the blood may be isolated, as a rule, from many different organs and tissues. All samples of blood set with Bact. abortum antigen were negative, irrespective of whether or not the organism was recovered from the blood or other tissues. This is in accordance with the findings of Carpenter in the female fetus,—the resistance is so feeble that few or no antibodies are formed to combat any existing infection. Bact. abortum was recovered in two cases from the vesicles, and in four cases from the testes, but in each instance the same organism was present in the blood or other tissues of the body.

The results from the tracts of the calves dying of calf infections are given in Group V, and show that five were negative. The other two showed B. coli, staphylococci, and streptococci, in the organs indicated by the chart.

In Group VI, the mature infertile or sterile bulls, there was a comparatively wide variation in the type of organisms encountered, but streptococci and micrococci were the most common invaders. In the order of the frequency of infection, the organs would be enumerated as follows: Vesicles, epididymis (usually the tail), scrotal sac, testes, prostate, and Cowper’s glands. The first three parts mentioned usually contained bacteria. A streptococcus was the usual invader of the scrotal sac, and very probably was the cause of the connective tissue tufts and strands so frequently seen. The vesicles and epididymes gave, in the order of the frequency of their occurrence, staphylococci, streptococci, B. coli, and Ps. pyocyaneus. The streptococci were usually of the viridans group, though a few were hemolytic, and two strains were indifferent to blood. The testes gave growths in only eleven instances,—staphylococci eight times, streptococci two times, and an unidentified rod once. The prostate yielded staphylococci twice and Cowper’s gland once.

As emphasized previously, the vesicles and tail of the epididymis are most subject to infection and degenerative changes. At the same time, they are intimately connected with the secretion of the semen. Once the epididymis becomes infected, there is nothing to prevent the organisms, together with inflammatory products, from being mixed with the semen and ejaculated during coitus. Also in the vesicles, unless the inflammation is so severe as to occlude the excretory duct, the organisms are mixed with the vesicular secretion, which is emptied into the urethra during ejaculation. Carried along with the bacteria, are, of course, toxic products, degenerated cells, and the otherwise altered secretion of the glands. One interesting case noted was that of a bull that had passed from a state of fertility to that of complete sterility during a period of two months. The semen was semi-fluid, greenish yellow in color, and contained a very few non-motile spermatozoa. Post mortem examination showed that the vesicles had undergone abscess formation and that they contained yellowish green material similar to that which had been discharged during copulation. Streptococcus hemolyticus and Ps. pyocyaneus were isolated from both vesicles, and from the semen. Micrococcus albus was isolated in nearly all cases of vesiculitis and was often associated with Streptococcus viridans or hemolyticus.

Bacteriological studies of the semen are, on the whole, more or less unsatisfactory, due to the present difficulty in obtaining samples free from any chance of contamination. In most of the abnormal bulls, bacteria of various types were isolated from the semen, most of which agreed culturally with those later isolated from the internal genital organs of the same tracts. The method of culturing consisted of douching the prepuce of the bull and vagina of the female with sterile saline solution before breeding. Samples of vaginal mucus were taken before service, and the flora compared to that after douching. This method of douching produced vaginal samples relatively free from bacteria, at least so much so that the post coital fluid demonstrated that many organisms must have been introduced from without. Whether or not they came in with the semen is problematical, but in all probability this was the method of introduction.

I have so far failed to obtain Bact. abortum from the tract of an adult animal, either by direct culture or guinea pig inoculation, except from the testicle of one abattoir bull. The agglutination tests with Bact. abortum antigen were all negative, except for two abattoir bulls. The results so far obtained would seem to indicate that, in accordance with the findings of other workers, the Bang organism seldom invades the male genital tract, or does not thrive there after its introduction. Schroeder (12) and others, have, however, on various occasions, recovered the organism from the bull, and the former author even states that it invades the vesicles and is eliminated with the semen.

Discussion

A complete discussion of those factors which have a bearing on reproduction and fertility in an animal, includes not only a thorough study of the genital tract, but an appreciative consideration of various extrinsic factors. The effect of environment has long been known to have a marked influence upon breeding, particularly with reference to animals in domestication. Diet, though long relegated to a minor phase of the question, has, within recent years, come to be a matter of prime importance with regard to its bearing upon the entire body metabolism. The endocrine organs preside over and regulate the growth and functioning of the genital organs from the earliest embryonic stage to the cessation of sexual life. Any derangement in one results in functional or organic changes in the other. In a given mating, we must take into consideration such factors as impediments to coitus, as well as those numerous agencies in the female which may interfere with the union of sperm and ovum, or with the successful implantation of the fertilized egg in the uterus, and its growth and development there till normal parturition takes place. Successful reproduction depends upon the mating of sexually sound females to equally sound males. Considering the various factors which govern reproduction, sexual soundness must necessarily depend, to a large extent, upon a good general condition of the entire body.

Environment: The effect of environment on fertility in the bull is no doubt a minor factor. Cases in which changes in environment affect fertility probably occur, however, particularly when fear and other psychic disturbances play a part. Marshall (29) states: “It would seem probable that failure to breed among animals in a strange environment is due not, as has been suggested, to any toxic influence on the organs of generation, but to the same causes as those which restrict breeding in a state of nature to certain particular seasons, and that the sexual instinct can only be called into play in response to certain stimuli,—the existence of which depends to a large extent upon appropriate seasonal and climatic changes.”