PATHOGENIC BACTERIA. 



105 



Colonies. They are exactly the same as typhoid the same 

 whetstone-shaped deep ones and the leaf-shaped surface ones. 



Potato. A thick yellow-brown pasty layer is formed instead 

 of the transparent almost invisible growth of the typhoid 

 bacil'us. 



Staining. Do not take Gram. Fuchsin stains them easily. 



Pathogenesis. When large quantities injected into guinea- 

 pigs, they die at times, sometimes with intestinal symptoms, 

 sometimes without. 



CHAPTER III. 



FIG. 52. 



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 

 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. 



Comma bacillus, pure cul- 

 ture. 600 diameters. 



