PATHOGENIC BACTERIA. 



109 



CHAPTER III. 



FIG. 57. 



PATHOGENIC BACTERIA CONTINUED. 



Spirillum Cholerse. (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 

 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 

 then as but a segment, a vibrio; each 

 arc is about three times as long as it 

 is broad, and possesses at each end a 

 flagella. 



Properties. They are very motile ; 



liquefy gelatine. They are easily affected by heat and dryness. 

 Spores have not been found, though some (Hiippe) claim arthro- 

 spores. 



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. 



Comma bacillus, pure cul- 

 ture. 600 diameters. 



