EXAMINATION OF "WATER 403 



lead to as decided a condemnation of the water as though an 

 organism possessing the precise morphological and cultural 

 characters of the Eberth-Gaif ky bacillus were isolated. 



While we would not agree with those who would regard 

 the bacteriological examination of water as useless, we still 

 further dissent from the view — if, indeed, it is seriously- 

 held by any — that the biological examination can in the 

 smallest degree supplant the chemical analysis of water, 

 which, on account of the valuable data it yields, must 

 always remain an integral part of the examination of 

 potable water. 



The most enthusiastic bacteriologist cannot deny that the 

 specific organism may have been present in a given water- 

 supply a week ago, and at the time of examination have 

 disappeared. The incubation period of enteric fever is 

 about fourteen days ; so that if a sample of drinking-water 

 were sent for examination when the disease declared itself, 

 it might easily be three weeks since the conveyance of 

 the infection, and during this time the Eberth-Gaffky 

 bacillus may have been annihilated by the common water 

 bacteria. 



Therefore, to say that a given water was safe because no 

 specific organism was demonstrable, and to ignore the 

 information that a chemical analysis might yield, would be 

 entirely illogical. 



The Isolation of the Cholera Bacillus from Water.— The 

 detection of Koch's comma bacillus {Spirillum cholerce 

 Asiaticce) in water, as in the case of the typhoid bacillus, is 

 a matter of some difiiculty, as this organism is rapidly over- 

 grown by the ordinary water bacteria. In the examination 

 of suspected water-supplies, the best method to employ for 

 the detection of this organism is to take advantage of the 

 fact, first noted by Dunham, that the cholera spirillum 

 multiplies with great rapidity in alkaline saline peptone 



26—2 



