220 MICROBIOLOGY 



brown. They approach the circular in outline, and in many 

 cases the margins are dentated. Perhaps the most distinct 

 characteristic of the abortion bacillus grown in this way is the 

 appearance of the larger colonies above described showing the 

 brownish center, gray rim and dentated edges. ' ' 



Bouillon. The three strains studied impart a very faint 

 cloudiness to the liquid. A small quantity of grayish viscid 

 sediment forms in the bottom of the tube. In glycerine bouil- 

 lon the growth is more vigorous. The strains studied show a 

 growth in the open bulb of the fermentation tubes but not in 

 the closed arm. The reaction is not changed in bouillon con- 

 taining dextrose, lactose or saccharose. 



Milk. Milk is not changed in its appearance. 



Life conditions and properties. This organism seems to 

 grow best at a temperature of about 37 C. It was first de- 

 scribed by Bang as an anaerobe but the English strain and 

 likewise those isolated by MacNeal and in this laboratory in 

 America grow in the presence of atmospheric oxygen. There 

 seems to be an endotoxin product that gives rise to an eleva- 

 tion in temperature shortly after the injection of cultures. 



M'Fadyean and Stockman prepared an "abortin" which 

 consisted of the liquid in which the organism was grown for 

 4 to 6 weeks, heated to 99 C. and filtered. With this filtrate 

 they tested infected cattle and found that a reaction some- 

 what similar to that following the injection of tuberculin in 

 tuberculous cattle was obtained in cases of infection. This 

 suggests a soluble toxin of some kind. The same authors de- 

 scribe a method of determining infected cattle by the "com- 

 plement fixation test" which indicates the production of spe- 

 cific antibodies. 



Sven Wall 8 reports excellent results in the diagnosis of 

 animals affected with the abortion bacterium by means of the 

 agglutination test and with the method of "fixation of com- 

 plement." He reports testing it on a very large number of 

 cattle. Holth 9 describes the morphology and cultural charac- 



Wall. Zeit. f. Infek der Haustiere, Bd. X (1911) p. 132. 



Holth. Zeit f. Infek der Haustiere, Bd. X (1911) p. 207. 



