than cows and induces a milder form of the disease. The resist- 

 ance appears to be due to certain anatomic and physiologic differ- 

 ences in their Sexual organs which make them less favorable places 

 for the growth of the abortion germs than those of the opposite 



sex." 



Buck, Creech, and Ladson (6) applied the agglutination test to 

 325 mature bulls, of which 288 were negative and 37 positive. 

 Bacillus abortus Avas isolated from five animals, of which three 

 showed marked lesions, two in the seminal vesicles, and one in the 

 left testicle. They conclude: " B. abortus may involve organs of 

 the generative apparatus of bulls, producing chronic inflammatory 

 changes. Of the generative organs, the seminal vesicles appear to 

 furnish the most favorable site for the lodgement and propagation 

 of abortion infection." 



Schroeder and Cotton (7) cite the case of a bull which reacted 

 to the abortion test and, on post mortem, Bact. dbortum was 

 isolated from an abscess of one epididymis. They state: "Our 

 attempts to produce a similar case of infection artificially failed, 

 and, in agreement with the difficulties many investigators have 

 had to obtain incriminating CAddence against bulls, we have thus 

 far failed to infect bulls in any way that justifies the assumption 

 that they are important factors in the dissemination of abortion 

 disease." Further, they conclude: " Regarding the dissemination 

 of abortion disease by bulls, we may say, however, that it would 

 be foolhardy in the dim light of our present knowledge to take 

 liberties with reacting bulls, or bulls from infected herds, or 

 promiscuously used bulls." 



Cotton (8)"^ failed to demonstrate the presence of abortion bacilli 

 in the genital organs of the bull used to serve aborting cows, or in 

 the testicles of two bull calves, one of which had been fed and the 

 other injected M'ith the cultures of the abortion bacillus. He con- 

 cludes that the bull does not harbor the organisms in the testicles. 

 Carpenter (9) injected both streptococci and Bact. abort um into 

 the scrotal sacs of young calves, and intravenously in others. In 

 no case was he able to recover the organisms from any part of the 

 genital canal, except for a streptococcus in one instance. Tiettger 

 and AYhite (10) were unable to obtain evidence of the presence of 

 Bact. abortum in three bulls slaughtered after repeated reactions 

 to the complement fixation and agglutination tests. The three 

 bulls had been under observation for three years, with no conclu- 

 sive evidence to indicate that they were a source of danger to the 

 herds in which they were a part. They believe that the bull trans- 

 mits the infection as a passive carrier. 



Attempts at artificial inoculation by natural channels have 

 failed, with the possible exception of McFadyean, Sheather, and 

 ]\rinett (11) who were able to infect the bull by the prepuce in two 

 cases and by the mouth in one case. The results, however, are by 

 no means conclusive. They conclude, nevertheless, that catth; of 

 any age of either sex may be infected by natural channels with the 

 bacillus of epizootic abortion. 



