BACILLUS ANTHEACIS 



337 



From plates the bacilli can be easily isolated, and the appear- 

 ances of pure cultures on various media studied. 



In bouillon, after twenty-four hours' incubation at 37° C, 



Fig. 99. — Anthrax bacilli arranged in chains, 

 from a twenty-four hours' culture on agar at 

 37° C. 



Stained with fuchsin. x 1000. 



there is usually the appearance of 

 irregular spiral threads suspended in 

 the liquid. These, on being examined, 

 are seen to be made up of bundles 

 of parallel chains of bacilli. Later, 

 growth is more abundant, and forms 

 a flocculent mass at the bottom of 

 the fluid. 



In gelatin stab cultures, the char- 

 acteristic appearance can be best 

 observed when a low proportion, say, 

 7J per cent., of gelatin is present, and 

 when the tube is directly inoculated 

 from anthrax blood. In about two 

 days there radiate out into the medium 

 from the needle track numberless very 

 fine spikelets which enable the cultures to be easily recognised. 

 These spikelets are longest at the upper part of the needle track 

 (Fig. 100). Not much spread takes place on the surface of the 

 gelatin, but here liquefaction commences, and gradually spreads 

 down the stab and out into the medium, till the whole of the 



Fig. 100.— Stab culture of 

 the anthrax bacillus in 

 peptone - gelatin ; seven 

 days' growth. It shows 

 the "spiking," and also, 

 at the surface, com- 

 mencing liquefaction. 

 Natural size. 



