BACILLUS ANTHRACIS AND ANTHRAX 



777 



the top where the oxygen supply is greatest. Simultaneously with 

 this a slimy mass appears at the bottom of the tube, owing to the 

 sinking of bacilli to the bottom. Apart from isolated flakes and 

 threads the intervening broth is clear. Shaken up, the tube shows 

 a tough, stringy mass, not unlike a small cotton fluff, and general 

 clouding is produced only by vigorous mixing. 



Upon agar plates, growth at 37.5 C. is vigorous and colonies 

 appear within twelve to twenty-four hours. They are irregular in 



FIG. 80. BACILLUS ANTHBACIS. In smear of spleen of animal dead of anthrax. 



outline, slightly wrinkled, and show under the microscope the char- 

 acteristic tangled-thread appearance seen on gelatin, except that 

 they are more compact than upon the former medium. The colonies 

 are slightly glistening and tough in consistency. 



On agar slants, the colonies usually become confluent, the entire 

 surface soon being covered by a grayish, tough pellicle which, if 

 fished, has a tendency to come away in thin strips or strands. 



On potato, growth is rapid, white, and rather dry. Sporulation 

 upon potato is rapid and marked, and the medium is favorable for 

 the study of this phase of development. 



Milk is slowly acidified and slowly coagulated. This action is 

 chiefly upon the casein; very few, if any, changes being produced 



