132 



STUDY AND IDENTIFICATION OF BACTERIA 



on the reaction of the media. Inasmuch as the recognition of vibrio shapes is of 

 importance in diagnosis he recommends that material from a stool be inoculated 

 into 3 tubes of peptone solution of reaction +0.3, 0.5 and i, respectively, one 

 of which would probably show vibrio morphology. 



FIG. 37. Cholera spirilla. (Kolle and Wassermann.) 



The cholera spirillum is very motile (a scintillating motility) and 

 liquefies gelatin fairly rapidly, although more slowly than any of the 

 spirilla mentioned in the key. 



*~v 



FIG. 38. Involution forms of the spirillum of cholera. (Van Ermengen.) 



The colony on gelatin was formerly considered characteristic, but like most 

 cultural characteristics, it is now considered as being only of confirmatory value; it 

 is not specific. These colonies show in twenty-four hours as small granular white 

 spots which have a spinose periphery. An encircling ring of liquefaction now 

 makes its appearance 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. 



