ANTHRAX STAB AND SLANT CULTURES. 235 



sterilized needle, one experiences a sensation that sug- 

 gests, somewhat, the matted structure of these colonies. 

 The bit that may thus be taken from a colony is always 

 more or less ragged. 



GELATIN. The colonies on gelatin at the earliest 

 stages also present the same wavy appearance ; but 

 this characteristic soon becomes in part destroyed by 

 the liquefaction of the gelatin which is produced by 

 the growing organisms. This allows them to sink to 

 the bottom of the fluid, where they lie as an irregular 

 mass. Through the fluid portion of the gelatin may be 

 seen small clumps of growing bacilli, which look very 

 much like bits of cotton-wool . 



BOUILLON. In bouillon the growth is characterized 

 by the formation of flaky masses, which also have very 

 much the appearance of bits of cotton. Microscopic 

 examination of one of these flakes shows the twisted 

 and plaited arrangement of the long threads. 



POTATO. It develops rapidly as a dry, granular, 

 whitish mass, which is more or less limited to the point 

 of inoculation. On potato, at the temperature of the 

 incubator, its spore- formation may easily be observed. 



STAB AND SLANT CULTURES. Stab and slant cul- 

 tures on agar-agar present in general the appearances 

 given for the colonies, except that the growth is much 

 mqre extensive. The growth is always more pronounced 

 on the surface than down the track of the needle. 



On gelatin it causes liquefaction, which begins on the 

 surface at the point inoculated, and spreads outward and 

 downward. 



It grows best with access to oxygen, and very poorly 

 when the supply of oxygen is interfered with. 



