DETECTION OF PATHOGENIC BACTERIA IN WATER 277 



Vestea ^ states that he was able to demonstrate by 

 this method the presence of the cholera bacilli in dejecta 

 suspected of being choleraic in character, although 

 microscopic examination had failed to reveal their 

 presence. Already at the end of fifteen hours a con- 

 siderable number of the comma-shaped bacilli were 

 found on the surface and at the edge of the liquid. 



Loeffler "-^ recommends the use of larger quantities 

 ■of water when search is being made for the cholera 

 organism. For this purpose, to 200 c.c. of the water 

 should be added 10 c.c. of alkaline broth- peptone, and 

 the mixture placed in the incubator for twenty-four 

 hours. 



Weibel,^ who has made a special study of spirillar 

 forms generally, draws attention to the property which 

 many spirilla possess of growing in very diluted culture 

 media, in which they are better able to hold their own 

 than the other organisms present, and they may thus be 

 more readily identified than when placed in more highly 

 nutritive media. Thus, if some material containing a 

 large number of vibrios, e.g. sewer-mud, is inoculated 

 into ordinary broth, the other organisms present multi- 

 ply so extensively that the spirilla are almost entirely 

 ■crowded out. If, on the other hand, the broth be diluted 

 with forty to fifty parts of sterile water, the spirilla re- 

 main in the majority, or at any rate gain the upper hand 

 in the course of a few days. Weibel found by this method 

 the Vibrio coli in the mucous flakes of diarrhoeic fasces, 

 'which never appears on gelatine-plates, and in ordinary 

 broth is at once crowded out by the B. coli communis. 

 Weibel recommends this method for the examination of 

 waters for spirillar forms. 



^ Centralhlatt filr BaMeriologie, vol. in., 1888, p. 320. 

 ' Ibid., vol. xiii., 1893, p. 384. 

 =* Ibid., vol. iv., 1888, p. 294. 



