78 SPIRILLUM CHOLERA 



assumes the " school of fish " appearance described 

 by Koch. It is the simply curved comma form 

 which is almost invariably met with in these 

 preparations. The comma bacillus stains with 

 fuchsine, methylene blue, or violet, but not 

 very readily ; it is not stained by the method of 

 Gram. 



From the mucous flakes found in the stools pure 

 cultures of the organism may be obtained in various 

 media, and a simple peptone-salt solution ( i % pep- 

 tone and '5% salt) is one of the most suitable. In 

 such a fluid medium the organism grows rapidly, 

 renders the fluid generally turbid, and forms a thin 

 pellicle on the surface, while the " comma " grows 

 into a spirillum. The spirilla forms are more 

 common in fluid than in solid media, but are by no 

 means confined to the former, and are very variable 

 in their length, their regularity of curvature, and 

 the closeness of the spiral. A bouillon culture pre- 

 paration, which, however, shows no long spirilla 

 forms but some S-shaped organisms, is represented 

 in Fig. 76, and may be compared with the prepara- 

 tion direct from the intestines. The preparation 

 (Fig. 77) is made from a 48-hours-old agar culture, 

 and shows more of the S-shaped and short spirilla 

 forms, as well as one or two of the E-shaped organ- 



