ASIATIC CHOLERA. 



365 



in a tank which contained the water supply of a neighbourhood 

 where cliolera cases occurred ; but comma-shaped organisms are 

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

 baoilh 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 5.5° C, and by 

 various antiseptic substances. 



Ill 



V.l 



I I 



u 



', I 



w 



ll I 





Fig. 154. — Pube-cultivatioks in Nutkient Gelatine. «, Koch'.s Choleka 

 Bacillus, twenty-tour hours old. b, Finklee'h Bacill-us, twenty-tour 

 hours old. 



Methods ui' 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 fuclisiue, or by the 

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



Nicati and EeUxch'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, theu 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 f uchsine dissolved in a saturated aqueous solution of 

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



