3 i6 



MANUAL OF BACTERIOLOGY. 



pointed ends, hence the name " comma " bacillus. The 

 curved forms, placed end to end, may produce an S-shaped 

 body. The length is from .8 to 2 n and the breadth from 



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Spirillum of cholera. (X 1000.) 



.3 to .4//. In cultures, genuine spirilla may be seen. In the 

 whitish particles found in the stools of cases of cholera the 

 organisms may be present in very large numbers. In these 

 particles they may exhibit a very curious arrangement, lying 

 parallel with one another, and, as remarked by Koch, they 

 resemble a school of fish moving 1 up stream. Involution 

 forms, irregular in outline and staining poorly, are often 

 seen in old cultures. The organism is motile, having a 

 rlagellnm at one end. It does not form spores. It stains 

 with the ordinary aniline dyes, but not by Gram's method. 

 It is aerobic. It grows at the room temperature, but better 

 in the incubator. On the ordinary media the growths are 

 whitish. It grows best on neutral or alkaline media, and is 

 very sensitive to a small amount of acid. It liquefies gelatin. 

 The colonies on gelatin plates have a very characteristic 



