THE COMMA BACILLUS OF ASIATIC CHOLERA 157 



Cover-glass specimens are prepared from the mucus in the faeces, 

 stained with a reduced solution of carbol fuchsin. The diagnosis of 

 Asiatic cholera is very probable when the individual bacilli appear to 

 lie behind each other in a direction like a small swarm of fish in a 

 slowly running stream, but, nevertheless, culture experiments must 

 be instituted. 



(2.) Examination by Cultures. Gelatine plate cultures are 

 instituted from the faeces, when possible from a flake of mucus. The 

 usual reductions are made (see Technique, 108) for the special 

 characteristic growth on gelatine of the colonies of Koch's bacillus 

 (see Biological Characters, p. 154). 



(3.) The Peptone Water Culture Method of Koch and Schotellius. 

 Besides the institution of plate cultures, peptone water cultures 

 must be prepared, because in cases where the cholera bacilli are not 

 numerous they do not develop, being overcome by the ordinary faeces 

 bacteria. 



An Erlenmeyer flask containing 1 per cent, peptone and J per 

 cent, common salt solution is inoculated with a platinum loop of the 

 suspected faeces or mucus and placed in the incubator at 37 C. As 

 soon as the fluid exhibits the slightest trace of turbidity, which 

 generally occurs in six to ten or twelve hours, a portion is removed 

 from the surface and examined in a hanging-drop, and cover-glass 

 specimens prepared. If a pure culture is obtained, then the diagnosis 

 is assured. It is not always so simple, as the surface growth is some- 

 times contaminated with other bacteria, most frequently the Bacterium 

 coli commune, and it is therefore necessary to make plate cultures, 

 and by this means isolate the Koch bacillus, which has now increased 

 in the peptone solution, and numerous colonies develop in the Petri- 

 dishes. 



Pure cultures are now prepared from the plate cultures, and tested 

 by the nitroso-indol reaction, as well as by the previously mentioned 

 Gruber and PfeifFer reaction. Animal experiments are also instituted. 

 Should all these tests yield positive results, then the diagnosis is con- 

 clusive and certain. Agar plates can be used instead of gelatine 

 plates, and possess the advantage that they can be placed in the 

 incubator at 37 C. and examined in eight to ten hours. 



THE EXAMINATION OF WATER FOR CHOLERA 

 BACILLI. 



It is necessary, to obtain satisfactory results, to use enormous 

 quantities of the suspected water. About 100 to 1000 c.c. of the 



