SPIRILLACEiE AND THE DISEASES CAUSED BY THEM 365 



The bacteriological diagnosis depends altogether upon the recog- 

 nition of th3 cholera germ in the feces. During an epidemic of 

 the disease a probable diagnosis in the individual case may be 

 made by mere microscopic examination of stained preparations 

 of the mucous flakes in the stools. The presence of abundant 

 curved rods arranged parallel to each other is sufiicient for a 

 probable diagnosis. The problem presents itself in a different 

 phase when it is necessary to recognize the first case of cholera in 

 a given locality. Here it is necessary to follow up the microscopic 

 diagnosis by cultures on gelatin plates, agar plates and in pepton 

 solution, and the identification of the cultured organisms by ag- 

 glutinating them with a known cholera-immune serum in high 

 dilution (i : 1000). The serum should be powerful enough in a 

 dilution of i : 10,000 to agglutinate very definitely the culture 

 used in producing it. The examination of immigrants for the detec- 

 tion of cholera carriers also requires culture work. The stool should 

 be passed naturally, but a dose of salts is permissible if there is too 

 great delay. About i gram of feces is mixed with 50 c.c. of sterile 

 pepton solution^ in a flask, and this is incubated at 37° C. for 

 six to eight hours. A stained preparation is then made from the 

 surface fihn of the flask. If no curved rods are found in it, the 

 specimen is probably negative. A loopful of the surface film 

 should nevertheless be transferred to a tube of pepton solution 

 which is incubated for six hours and again examined microscopic- 

 ally. If curved rods are found microscopically on the surface 

 film of either the first or second culture, the problem of differentiat- 

 ing between the cholera vibrio and other similar organisms is 

 presented. Plate cultures on gelatin at 22° C. and on agar at 

 37° C. should be made and at the same time the transplantation 

 to fresh pepton solution should be continued at six-hour intervals. 

 After eighteen hours, one examines the plates for tj^ical colonies 

 and subjects these to agglutination tests with specific serum of 

 high titre. The bacteria from the surface film of the pepton solu- 

 tion are also tested in the same way. A rapid clearing of the 



• Pepton 10, NaCI 10, NaNOa o.i, NaCOs 0.2, distilled water 1000. 



