CHAPTER VI 



THE COLON GROUP OF BACILLI AND METHODS FOR 

 THEIR ISOLATION 



The Colon Group of Bacilli. The Bacillus coli was 

 first isolated by Escherich (Escherich, 1884) from the 

 faeces of a cholera patient. It was subsequently found 

 to be a normal inhabitant of the intestinal tract of man 

 and many other animals, and to occur regularly in 

 their excreta, and on this account it became of the 

 highest interest and importance to sanitarians, since 

 its presence in water-supplies was regarded as direct 

 evidence of sewage pollution. 



Specific disease germs are difficult to isolate even 

 when they are present; and water may of course be 

 grossly polluted with sewage without any specific 

 disease germs being there at all. All sewage-polluted 

 water, however, is potentially dangerous, since where 

 faecal matter exists, disease germs are at any time likely 

 to appear. A test for faecal material as distinguished 

 from infected material is, therefore, essential; and 

 for such a test the colon group of bacilli are specially 

 well suited. They are not dangerous in themselves, 

 but they are significant as indices 'of the probable 

 presence of disease germs. 



The so-called Bacillus coli may be described as a short, 



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