DETECTION OF PATHOGENIC BACTEEIA IX WATER 267 



bacilli in a well-water which was situated in close 

 proximity to a privy. This author mentions that he 

 was only able to discover them by examining the de- 

 posit of the water by means of an apparatus specially 

 constructed by him for the investigation of the sediment 

 left by water. The author suggests this as a useful 

 method for detecting other pathogenic organisms in 

 water. 



We will refer the reader to the account, which will 

 be found later, of the special methods which have been 

 devised for the detection of typhoid bacilli in water in 

 the presence of other organisms. It is possible that in 

 some of the earlier investigations which we have re- 

 corded, although the typhoid bacillus M^as very possibly 

 present in the water, yet its actual detection, although 

 alleged to have been accomplished, remains doubtful, 

 as the methods employed were not so accurate as those 

 more recently used. In this connection we would also 

 refer the reader to the elaborate papers of Cassedebat ^ 

 and Dunbar,'^ which discuss in detail the endeavours 

 which have been made to differentiate between the ty- 

 phoid bacillus and other forms closely resembling it 

 which are also found in water. 



Detection of Typhoid Bacillus in Water 



We have already drawn attention to the fact that 

 doubt attaches to the identification of the typhoid 

 bacillus in waters recorded by some of the earlier in- 

 vestigators to whose work we have had occasion to 

 refer above. This uncertainty is due to the almost 

 constant presence with the typhoid bacillus in water of 

 other organisms so closely resembling it, that their 



^ Annales de Vlnstitut Pasteur^ voLiv., 1890, p. 625. 

 ^ Zeitschrift f. Hygiene, voL xii., 1892, p. 485. 



