ANTHRAX. 289 



mounted in Canada balsam. The bacillus can be stained with 

 all aniline dyes and also by the method of Gram. 



Cultivation of Anthrax-bacilli. The anthrax-bacillus is 

 extremely indifferent with regard to its nutrient material. It 

 will develop in the absence of oxygen, but it does not then gen- 

 erate a peptonizing ferment. The temperature-minimum is 12 

 C. (53.6 F.); the temperature-optimum, 35 C. (95 F.) ; 

 the temperature-maximum, 45 C. (113 F.). 



On gelatin-plates, with a magnification of from 80 to 100, 

 the superficial colonies appear as round discs of yellowish color, 

 constituted of a tangle of threads which form a dense, impene- 

 trable convolution at the center. Especially the border presents 



Fig. 64. Bacillus anthracis: colony three days old upon a gelatin-plate; impress- 

 preparation; X 1000 (Frankel and Pfeiffer). 



quite distinctly this filamentous structure, and from it fre- 

 quently passes off a delicate network of convoluted and curled 

 processes, which gives the colonies their characteristic appear- 

 ance. The gelatin in the neighborhood is softened, and begins 

 slowly to undergo liquefaction. 



In gelatin stab-cultures the line of inoculation forms a whitish 

 band, from the circumference of which numerous ramifying 

 processes extend into the gelatin. Liquefaction of the culture- 

 medium progresses slowly, the nonmotile bacilli, by reason of 

 their weight, sinking to the bottom of the liquefied area. 



In bouillon small fragments appear and fall to the bottom ; 

 they represent a union of the anthrax-bacilli for the formation 

 of convolutions of filaments. 

 19 



