256 A MANUAL OF BACTERIOLOGY 



dead of anthrax. This microbe grows in nutrient 

 gelatine, agar-agar, neutral bouillon, and on steamed 

 potatoes at all temperatures between 15 and 43 C., 

 best between 25 and 40 C. Free access of air is 

 essential for B. anthracis to produce spores. Suc- 

 cessive cultivations of this microbe do not weaken 

 its virulence. On gelatine plates it gives rise to 

 small white colonies after two or three days' incuba- 

 .tion. When these colonies are examined under low 

 power they appear as masses of twisted threads, 

 but in cover-glass preparations (Fig. 50 B) these 

 thread-like filaments are readily observed. In tube- 

 cultivations the bacillus presents a characteristic 

 appearance. Along the track of the needle there 

 appear lateral growths which give the culture a 

 peculiar feather-like appearance. But after a time 

 the gelatine liquefies, and the growth sinks to the 

 bottom of the tube, where the bacilli undergo de- 

 generation. On agar-agar a similar appearance is 

 presented, but there is no liquefaction of the medium. 

 B. anthracis grows on steamed potatoes as a creamy- 

 white granular mass. 



It has been stated that the anthrax bacillus pro- 

 duces a ptomaine called anthracin and an albumose l 

 from the medium on which it lives. 



Klein and Parsons 2 have shown that anthrax 

 bacilli without spores are destroyed in five minutes 

 when exposed to a temperature of 103 C. (dry heat), 

 but the spores are not destroyed until they have 



1 Hankin in Proc. Roy. Soc., 1890, p. 93; and Martin in 

 Nature, vol. xlii. p. 118. 



2 Report to Medical Officer of Local Government Board , 1884. 



