ASIATIC CHOLERA. 365 



in a tank which contained the water supply of a neighbourhood 

 where cholera cases occurred; but comma-shaped organisms are 

 frequently present in sewage-contaminated water. Koch's comma- 

 bacilli are aerobic, and their development is arrested by deprivation 

 of oxygen. They are destroyed by drying on. a cover glass, but 

 retain their vitality longer when dried on silk threads. Cultures 

 are sterilised by exposure for fifteen minutes to 55 C., and by 

 various antiseptic substances. 



FIG. 154. PURE-CULTIVATIONS IN NUTRIENT GELATINE, a, KOCH'S CHOLERA 

 BACILLUS, twenty-four hours old. I, TINKLER'S BACILLUS, twenty-four 

 hours old. 



METHODS OF STAINING THE COMMA-BACILLI OF KOCH. 



In cover-glass preparations they may be well stained in the ordinary 

 way, with an aqueous solution of methyl-violet or fuchsine, or by the 

 rapid method, without passing through the flame (p. 85, Babes' method). 



Nicati and Reitsch's method. 



A small quantity of the stools, or of the scraping of the intestinal 

 mucous membrane, is spread out on a glass slide and dried, then steeped 

 during some seconds in sublimate solution, or in osmic acid (1 to 100). 

 It is then stained by immersion in fuchsine-aniline solution (1 or 2 

 grammes of Bale fuchsine dissolved in a saturated aqueous solution of 

 aniline), washed, dried, and mounted in Canada balsam. 



