54-8 Hog-cholera 



surfaces are brown by reflected light, and without markings. 

 They are rarely larger than 0.5 mm. in diameter and are 

 homogeneous throughout. The superficial colonies have 

 little tendency to spread upon the gelatin. Their borders 

 may be circular and rounded, or irregular. They rarely 

 reach a greater diameter than 2 mm. The gelatin is not 

 liquefied. There is nothing distinctly characteristic about 

 them. 



Upon agar-agar they attain a diameter of 4 mm. and 

 have a gray, translucent appearance with polished surface. 

 They are round and slightly arched. 



Gelatin. In gelatin punctures the growth takes the form 

 of a nail with a flat head. There is nothing characteristic 

 about it. 



Agar-agar. Linear cultures upon agar-agar present a 

 translucent, circumscribed, grayish, smeary layer without 

 characteristic appearances. 



Potato. Upon potato a yellowish coating is formed, 

 especially when the culture is kept in the thermostat. 



Bouillon. Bouillon made with or without peptone is 

 clouded in twenty-four hours. When the culture is allowed 

 to stand for a couple of weeks without being disturbed, a 

 thin surface growth can be observed. 



Milk. Milk is an excellent culture medium, but is not 

 visibly changed by the growth of these bacteria. Its reac- 

 tion remains alkaline. 



Vital Resistance. The bacillus is hardy. Smith found 

 it vital after being kept dry for four months. It ordinarily 

 dies sooner, however, and I have experienced difficulty in 

 keeping it in the laboratory for any length of time unless 

 frequently transplanted. The thermal death-point is 54 C., 

 maintained for sixty minutes. 



Metabolic Products. Gas-production. The hog-chol- 

 era bacillus is a copious gas-producer, capable of break- 

 ing up dextrose and lactose into CO 2 , H, and an acid, which, 

 formed late, eventually checks its further development. It 

 does not ferment saccharose. 



Indol. No indol and no phenol are formed in the culture 

 media. 



Toxin. In pure cultures of the hog-cholera bacillus 

 Novy* found a poisonous base with the probable composition 

 C 16 H 26 N 2 , which he gave the provisional name "suso toxin." 



*" Medical News," 1890, p. 231. 



