THE TEST FOR THE BACILLUS OF CHOLERA 113 



encies to locate in the bile duct or gall-gladder, where it may re- 

 main dormant for a long period of time. This observation has led 

 to the use of bile as an enriching medium for both organisms. 



The cholera vibrio work in the food and drug laboratory may 

 resolve itself into the isolation of the germ from water supplies, 

 from vegetables and possibly from feces and from sewage, and 

 consists in the use of special culture media, special cultural methods, 

 inoculation methods and agglutination tests. It is interesting to 

 note that the method now in use for isolating the cholera vibrio 

 from water supplies is the original 

 Koch method, done as follows. 

 Add i per cent, each of peptone 

 and salt to 100 cc. of the suspected 

 water and incubate at 38 C. 

 Examine microscopically at inter- 

 vals of 8, 12 and 18 hr. As soon 

 as curved and comma -shaped 

 organisms appear, plate on agar 

 and make such additional tests 

 as may be necessary to prove the .FIG. 35. S. cholera showing invo- 



r , i i i j lution forms (X 1000). (MacNeal, 



presence of the cholera germ, such after VanEmengen.) 

 as the nitroso reaction, agglutina- 

 tion test, Pfeiffer's phenomenon, etc. It is not practical to enter 

 into a fuller discussion of the subject. More complete details will 

 be found in the works on bacteriology and in bulletins and reports 

 on bacteriology and on hygiene. For example, the U. S. Public 

 Health Service has worked out a quick routine method for isolat- 

 ing the cholera germ from feces, used in the U. S. Quarantine Ser- 

 vice and at the quarantine station of New York, as reported in 

 the Journ. of the Am. Pub. Health Association (Dec., 1911) and 

 a condensed summary of the general methods may be found 

 in the admirable little work by Stitt (Practical Bacteriology, 

 Blood Work and Parasitology, 1913). Numerous special reports 

 will be found in American and foreign bacteriological literature. 



