BY R. GREIG SMITH. 747 



added. Billings and Peckham* found that Bact. typhi and coli 

 c<> ni in une were more resistant to the antiseptic action of light 

 than water bacteria. 



Marpmannf has described a method which he employs for 

 separating three noxious classes of bacteria from water. To the 

 water is added an equal quantity of neutral bouillon, and the 

 mixture is incubated at 30° C. for 24 hours in order to increase 

 the numbers of the bacteria. At the end of this incubation 

 period, a portion of the mixed culture is inoculated into nutrient 

 gelatine containing - 2% citric acid and maintained at 20°-22°C. 

 The colonies that grow are examined for Bact. typhi. Another 

 portion is inoculated into gelatine containing 2% sodium carbo- 

 nate and kept at 10°- 18° C The colonies are examined for 

 cholera vibrions as well as the cloaca bacteria, which include the 

 putrefactive microbes commonly found in the animal intestine, 

 the representative organism being Bact. coli commune. Another 

 portion is inoculated into nutrient agar containing 2% sodium 

 carbonate, kept at 30°- 37° and examined for cadaver bacteria. 

 The last two groups are really subdivisions of one which includes 

 all intestinal (sewage, excrement, etc.) bacteria. They induce a 

 foul or putrefactive fermentation of albuminoids and carbo- 

 hydrates. 



Theobald Smith J separates Bact. coli commune by adding 

 quantities of the water varying from - l to 1 c.c. to 10 fermen- 

 tation tubes containing 1% glucose bouillon. In the presence of 

 coli 40 to 60% of the volume of the tube contains gas in from 3 

 to 4 days. The reaction of the medium becomes strongly acid 

 (5 c.c. tenth normal alkali are required to neutralise 10 c.c). 

 Plates are prepared from the most probable tubes before the end 

 of a week. It is to be noted that a production of gas and acid, 

 very similar to Bact. coli commune, is produced by varieties of 

 Proteus, Bad. cloaccn and the Bact. lactis aerogenes group of 

 bacteria. 



* Billings and Peckham, Centralblatt fur Bakt. 1 Abt. xix., 244, Bef. 



tMarpmann, Centralblatt fur Bakt. 1 Abt. xvii., 362. 



J Theobald Smith, Centralblatt fur Bakt. 1 Abt. xviii., 494, Ref. 



