CHOLERA. 



95 



rapidly, although more slowly than any of the spirilla mentioned in 

 the key. The colony on gelatin was formerly considered charac- 

 teristic, but like most cultural characteristics, it is now considered as 



FIG. 36. Cholera spirilla. (Kolle and Wassermann.} 



being only of confirmatory value; it is not specific. These colonies 

 show in 24 hours as small granular white spots which have a spinose 

 periphery. An encircling ring of liquefaction now makes its appear- 



FIG. 37. Involution forms of the spirillum of cholera. (Van Ermengem.) 



ance and the highly refractile (as if fragments of sparkling glass) 

 colony can be separated into a granular center, a striated periphery 

 and a clear external ring of liquefaction. 



