404 



Anthrax 



Fig. 126. Bacillus an- 

 thracis ; gelatin stab cul- 

 ture, showing character- 

 istic growth with com- 

 mencing liquefaction and 

 cupping (from evapora- 

 tion) at the surface of 

 the medium (Curtis). 



surface of the medium, where they 

 spread out into flat, irregular, 

 transparent tufts like curled wool. 

 From a tangled center large num- 

 bers of curls, made up of parallel 

 threads of bacilli, extend upon the 

 gelatin. As soon as the colony at- 

 tains to any considerable size lique- 

 faction becomes rapid. Beautiful 

 adhesion preparations can be made 

 if a perfectly clean cover-glass be 

 passed once through a flame and 

 laid carefully upon the gelatin, the 

 colonies being picked up entire as 

 the glass is carefully removed. Such 

 a specimen can be dried, fixed, and 

 stained in the same manner as an 

 ordinary cover-glass preparation. 



Gelatin Punctures. In gelatin 

 puncture cultures the growth is 

 even more characteristic than are 

 the colonies. The bacilli begin to 

 grow along the entire track of the 

 wire, but develop most luxuriantly 

 at the surface, where oxygen is 

 plentiful and where a distinct 

 shaggy pellicle is formed. From the 

 deeper growth, fine filaments extend 

 from the puncture into the sur- 

 rounding gelatin, with a beautiful 

 arborescent effect (Fig. 126). 



Liquefaction progresses from 

 above downward until ultimately 

 the entire gelatin is fluid and the 

 growth sediments. 



Agar-agar. Upon agar-agar 

 characteristic appearances are few. 

 The growth takes place along the 

 line of inoculation, forming a 

 grayish-white, translucent, slightly 

 wrinkled layer with irregular edges, 

 from which curls of bacillary threads 

 extend upon the medium. When 



