BACILLUS A NT HR AC IS. 277 



slightly dimpled so as to resemble somewhat the proximal 

 end of a phalanx. Their protoplasm is very finely granular, 

 and sometimes appears surrounded by a thin unstained 

 capsule. When several bacilli lie end to end in a thread, 

 the capsule seems common to the whole thread (Fig. 74). 

 They stain well with all the basic aniline dyes and are not 

 decolorised by Gram's method. 



Plate Cultures. From a source such as that indicated, 

 it is easy to isolate the bacilli by making gelatine or 

 agar plates. If, after 

 twelve hours' incuba- 

 tion at 37 C. the 

 latter be examined 

 under a low objec- 

 tive, colonies will be 

 observed. They are 

 to be recognised by 

 beautiful wavy wreaths 

 like locks of hair, 

 radiating from the 

 centre and apparently 

 terminating in a point 

 which, however, on 

 examination with a 



, i r IG. 70. iMirlace colony of the anthrax 



higher power is bacillus on an agar plate> showing the 



observed to be a fila- characteristic appearances. x 30. 



ment which turns 



upon itself (Fig. 70). The whole colony is, in fact, probably 

 one long thread. Such colonies are very suitable for making 

 impression preparations (vide p. 109) which preserve per- 

 manently the appearances described. On examining such 

 with a high power, the wreaths are seen to be made up 

 of bundles of long filaments lying parallel with one another, 

 each filament consisting of a chain of bacilli lying end to 

 end, and similar to those observed in the blood (Fig. 71). 



On gelatine plates, after from twenty-four to thirty-six 

 hours at 20 C., the same appearances manifest themselves, 

 and later they are accompanied by liquefaction of the 



