164 BACTERIA 



ANTHRAX BACILLUS. 



Bacillus Anthracis. 



Anthrax Bacillus of Koch. (Fig. 54.) 



Practically the first pathogenic organism to be isolated. This 

 was accomplished by Dr. Robert Koch. It is the cause of a wide- 

 spread malignant disease, variously called Anthrax, Charbon, or 

 Splenic Fever. Animals and man are infected by it, and its action 

 is often rapidly fatal. 



Morphology and Stains. In animal tissues this organism ap- 

 pears as a large rod 3-io/z long, and i-i.2fi wide. Is often in pairs 

 or chains. In fresh specimens the ends of the rods are rounded; 

 when older, the ends become square or con- 

 cave. Often they have faint capsule sur- 

 rounding them. In culture media they ex- 

 hibit spores and grow in long threads, these 

 threads form long spirally twisted masses, like 

 locks of wavy hair. No flagella are formed, 

 and the organism is not motile. In old cul- 

 tures ' bizarre involution forms are found. It 

 (Greene's Medical stains well with all the common basic dyes 



and by Gram's method. 



Oxygen Requirements. Is a facultative anaerobe, but grows 

 much better in the presence of oxygen. If oxygen is excluded, no 

 liquefaction occurs. 



Temperature. Grows between 14 C. and 45 C.; best at 37 C. 

 Spores are formed, if oxygen is abundant, above 12 C. Sporu- 

 lation is more rapid at 37 C. Spores withstand high temperature 

 (dry) for a long time, 100 C. for one hour. The bacillus itself is 

 killed at 70 C., moist heat, in one minute. The thermal death- 

 point may be put down for the organism, at 100 C. moist, for 

 five minutes. 



Vital Resistance. Highly resistant to chemicals, light and dry- 

 ing. Spores resist 5 percent carbolic solution for days (Esmarch), 



