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CONTRIBUTION TO THE BACTERIAL FLORA OF THE 

 SYDNEY WATER SUPPLY, II. 



By R. Greig Smith, M.Sc, Macleay Bacteriologist to the 

 Society. 



Many pathogenic bacteria have been separated from water or 

 from mud lying beneath well and river waters by inoculating the 

 water, either before or after concentration, or the mud, directly 

 into the tissues of animals in which the non-pathogenic organisms 

 disappear whilst the pathogenic bacteria multiply and produce 

 their characteristic lesions. Several pathogenic bacteria have 

 been discovered in this way, as for example, Bac. cuniculicida 

 and Bac. hydrophilus fuscus. This method, however, is only 

 applicable in the separation of organisms pathogenic to animals, 

 and is of no use for organisms such as Bad. typhi and Vibrio 

 cholera, which are parasitic in man only. The former organism 

 is perhaps the most to be feared in the water of this country. 

 The latter is fortunately still a stranger. Before going further, it 

 may be said that the separation of Bad. typhi is extremely diffi- 

 cult, so much so, that except in cases where there is gross 

 pollution with typhoid dejecta the organism cannot be separated. 

 The difficulty is due perhaps to our methods, or perhaps to the 

 fact that by the time the water is suspected the contami- 

 nation has passed away after having produced the harm, and 

 consequently the bacteriologist cannot find the causative organism 

 in the water. 



The methods that have been suggested for isolating the 

 organism depend upon the inability of the commonly occurring 

 water bacteria to grow upon certain media in which the typhoid 

 and intestinal bacteria grow pretty freely. To this latter group 

 of bacteria belong Bact. coli commune and its allies, which, un- 

 fortunately, are more resistant to chemical agents than Bact. 



