550 APPLICATION OF METHODS OF BACTERIOLOGY 



This organism, commonly known both as the spirillum 

 of Asiatic cholera, and, because of its morphology, as Koch's 

 "comma bacillus/' is identified by the following peculiarities: 



MICROSPIRA COMMA (KOCH), SCHROTER, 1886. 



SYNONYMS. Comma-bacillus, Koch, 1884; Spirillum cholerae Asiatica, 

 Fliigge, 1886. 



Morphology. It is a slightly curved rod, ranging from 

 about 0.8 to 2fj. in length and from 0.3 to 0.4^ in thickness 

 that is to say, it is usually from about one-half to two- 

 thirds the length of the tubercle bacillus, but is thicker and 

 plumper. Its curve is frequently not more marked than 

 that of a comma, and, indeed, it is often almost straight; 

 at times, though, the curve is much more pronounced, and 

 may even describe a semicircle. Occasionally the curve 

 may be double, one comma joining another, with their 

 convexities pointing in opposite directions, so that a figure 

 similar to the letter S is produced. In cultures long spiral 

 or undulating threads may often be seen. From these 

 appearances this organism cannot be considered as a bacillus, 

 but rather as an intermediate type between the bacilli and 

 the spirilla. Koch thinks it not improbable that the short 

 comma forms represent segments of a true spirillum, the 

 normal form of the organism. (Fig. 86.) 



It does not form spores, and we have no reliable evidence 

 that it possesses the property of entering, at any time, a 

 stage in which its powers of resistance to detrimental agencies 

 are increased. 



It is a flagellated organism, but has only a single flagellum 

 attached to one of its ends. 



