124 ESSENTIALS OF BACTERIOLOGY. 



CHAPTER III. 



PATHOGENIC BACTERIA CONTINUED. 



Spirillum Cholerae. (Koch.) Comma bacillus of cholera. 

 Origin. Koch, as a member of the German expedition sent 

 to India, in 1883, to study cholera, found this micro-organism 

 in the intestinal contents of cholera 

 FIG. 63. patients, and by further experiments 



identified it with the disease. 



Form. The microbe as seen ordi- 

 narily appears as a short, arc-like body, 

 about half the size of a tubercle bacillus, 

 but when seen in large groups, spirals 

 are formed, each little arc appearing 

 * nen as kut a se S men t) a vibrio; each 

 arc is about three times as long as it 

 Comma bacillus, pure cui- is broad, and possesses a flagellum at 



ture. 600 diameters. one or more ra rely both ends. 



Properties. They are very motile ; liquefy gelatine. They are 

 easily affected by heat and dryness. Spores have not been 

 found, though some (Hiippe) claim arthrospores, but these 

 bodies represent only degenerative changes. 



Growth. Develops at ordinary temperatures on all nutrient 

 media that have an alkaline or neutral reaction. They are 

 facultative anaerobic. 



Colonies, gelatine. After 24 hours, small white points which 

 gradually come to the surface, the gelatine being slowly lique- 

 fied, a funnel-shaped cavity formed holding the colony in its 

 narrow part, at the bottom, and on the fifth day all the gelatine 

 is liquid. If the colonies of three days' growth are placed under 

 microscope they appear as if composed of small bits of frosted 

 glass with sharp irregular points. 



