240 Journal of Agricultural Research voi. xvii. no. $ 



involving a considerable number of animals, in an endeavor to ascertain 

 with what frequency abortus infection could be demonstrated in the 

 generative organs of bulls giving positive or suspicious reactions to the 

 agglutination test for this disease, and to determine whether or not 

 pathological changes are commonly associated with such infection. 



EXPERIMENTAL PROCEDURE 



The procedure employed by the writers consisted in securing blood 

 samples from the animals as they arrived at one of the abattoirs in close 

 proximity to Washington, D. C, for slaughter. No information was 

 available regarding the original source of the bulls or the exposure sus- 

 tained. Each sample was given a number corresponding to the serial 

 number of a tag that was attached to the animal's ear at the time of 

 bleeding. The blood samples were then taken to the laboratory for the 

 application of the agglutination test. At the time of slaughter, which 

 was usually the following day, those animals giving positive or suspicious 

 reactions were autopsied as carefully as abattoir conditions permitted 

 and the organs of the genital system were secured for further study. Cul- 

 tural work was depended upon as a means of detecting infection, the 

 medium employed consisting of 3 per cent glycerin infusion agar to which 

 approximately 5 per cent sterile blood serum was added. To reduce 

 the oxygen tension the inoculated tubes were subjected to incubator 

 temperature in closed jars in the presence of fresh cultures of Bacillus 

 subtilis. 



During the period from December 9, 1916, to July 7, 1918, the agglu- 

 tination test for abortion disease was applied to 325 mature bulls. Of 

 this number 288 gave negative results to the test. The manner in which 

 the remaining 37 reacted is of considerable interest, inasmuch as the 

 intensity of the reactions appeared to bear some relation to the cultural 

 results. 



The manner of applying the test consisted in the making of a i to 10 

 basic dilution of the blood serum. To the four tubes utilized for each 

 case were added 0.4, 0.2, o.i and 0.05 cc. of this basic dilution. The 

 amount of test fluid added to each tube was i cc. 



The vesiculae seminales, vasa deferentia, testes, and epididymides 

 were secured from the 37 bulls whose blood serum showed the pres- 

 ence of Bad. abortus agglutinins. From 15 to 20 tubes of medium 

 were utilized for culturing the various organs from each bull. These 

 investigations resulted in the demonstration of the presence of Bad. 

 abortus infection in four animals — No. 88, 98, 136, and 409 — and in the 

 detection of marked lesions in bulls 98 and 409. 



A brief description of the work performed and the findings in these 

 cases follow. 



