BACILLUS ANTHRACIS SYMPTOMATICI 497 



Material for inoculation is best obtained from the heart's blood, the 

 local swelling, or the peritoneal exudate of an animal dead of the 

 disease. The material should be sown anaerobically on ascitic or blood 

 agar plates or upon dextrose agar, the latter medium not being as 

 satisfactory. Pure cultures may be obtained readily by inoculating 

 guinea-pigs with morbid material and transferring some of the heart's 

 blood of the animal immediately after death to artificial media. 



Growth on Artificial Media. The organism grows to a limited extent 

 in plain broth if oxygen is excluded. It grows better in dextrose 

 broth. On anaerobic dextrose gelatin and dextrose agar plates the 

 colonies are round, oval, grayish, and possess distinctly filamentous 



FIG. 70. Bacillus of symptomatic anthrax spore formation. X 1000. 



edges. Gelatin is liquefied in from two to four days. Milk is a good 

 medium; the organism forms a slight amount of acid, but no coagula- 

 tion or peptonization takes place. 



Conditions of Growth. B. anthracis symptomatici is an obligate 

 anaerobe which does not grow below 14 C. nor above 44 C. The 

 optimum temperature is 37 C. The spores are extremely resistant to 

 heat; half an hour's exposure to 100 C. does not always kill them. 

 The spores appear to be able to remain latent in the animal body. 

 The virulence of vegetative organisms developing from spores is said 

 to be greatly reduced by heating the spores to 100 C. for two to three 

 minutes. 



Products of Growth. The organism forms a gelatinase. In dextrose 

 broth it produces carbon dioxide, hydrogen, and traces of methane, 

 as well as butyric and lactic acids. 



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