CHOLERA. 425 



The cholera spirillum stains well with the ordinary 

 aqueous solutions of the anilin dyes ; fuchsin seems par- 

 ticularly appropriate. At times the staining must be con- 

 tinued for from five to ten minutes to secure homogeneity. 

 The cholera spirillum does not stain by Gram's method. 

 It may be colored and examined while alive ; thus Cornil 

 and Babes, in demonstrating it in the rice-water dis- 

 charges, "spread out one of the white mucous fragments 

 upon a glass slide and allow it to dry partially ; a small 

 quantity of an exceedingly weak solution of methyl violet 

 in distilled water is then flowed over it, and it is flattened 

 out by pressing down on it a cover-glass, over which is 

 placed a fragment of filter-paper, which absorbs any 

 excess of fluid at the margin of the cover-glass. Comma 

 bacilli so prepared and examined with an oil-immersion 

 lens (x 700-800) may then be seen : their characters are 

 the more readily made out because of the slight stain 

 which they take up, and because they still retain their 

 power of vigorous movement, which would be entirely 

 lost if the specimen were dried, stained, and mounted in 

 the ordinary fashion." 



The colonies of the spirillum when grown upon gel- 

 atin plates are highly characteristic. They appear in 

 the lower strata of the gelatin as small white dots, grad- 

 ually grow out to the surface, effect a gradual liquefaction 

 of the medium, and then appear to be situated in little 

 pits with sloping sides (Fig. 90). This peculiar appear- 

 ance, which gives one the suggestion that the plate is 

 full of little holes or air-bubbles, is due to the evapora- 

 tion of the liquefied gelatin. 



One of the best methods of securing pure cultures of 

 the cholera spirillum, and also of making a diagnosis 

 of the disease in a suspected case, is probably that of 

 Schottelius. The method is very simple : A small quan- 

 tity of the fecal matter is mixed with bouillon and stood 

 in an incubating oven for twenty-four hours. If the 

 cholera spirilla are present they will grow most rapidly 

 at the surface of the liquid when the supply of air is 



