314 BACTERIOLOGY. 



THE MORPHOLOGICAL AND BIOLOGICAL PECULIAEITIES 

 OF THE SPIRILLUM OP ASIATIC CHOLERA. 



Morphology. It is a slightly curved rod of about 

 from 0.8 to 2.0 i« in length and from one-sixth to one- 

 third in thickness ; that is to say, it is from about one- 

 half to two-thirds the length of the tubercle bacillus, 

 but is thicker and plumper. Its curve is usually 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 a bacillus, but rather 

 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. 60.) 



Fig. 60. 



Spirillum of Asiatic cholera. Impression cover-slip from a 

 colouy thirty-four hours old. 



It does not form spores, and we have no reliable 

 evidence that it possesses the property of entering at 



