VAEIETIES OF COLOX BACILLI 197 



believes to be unimportant, and i6 per cent would be 

 condemned by Clemesha as containing true B. communis. 



Major Clemesha does not claim that these results 

 necessarily indicate any change of procedure in dealing 

 with the waters of temperate climates. Indeed, the 

 experience of English and American bacteriologists 

 offers pretty conclusive evidence that waters so stored 

 as to be safe do not contain large numbers of lactose- 

 fermenting organisms of any t>^e. In other tropical 

 countries and perhaps in warm summer weather, the 

 Indian conditions may possibly be duplicated (as we 

 know they are in the case of the forms fermenting 

 dextrose but not lactose) ; and the experiments reported 

 in this book deserve the careful consideration of water 

 bacteriologists and sanitarians. 



The results obtained by Houston (191 1) in London 

 unfortunately do not correspond at all with these 

 Indian data. Houston studied in detail the reactions 

 of about 800 strains of dextrose-fermenting bacteria 

 from raw river-water, stored water, and stored and 

 filtered water. Comparison of the relative prevalence 

 of types from these three sources ought to furnish some 

 confirmation of Major Clemesha's conclusions, even 

 although the extreme conditions of warmth and sun- 

 light are lacking. We find, however, on careful study 

 of the figures that they do not. The Houston types 

 corresponding to B. communis, B. Schafferi and B. 

 neapolitanus (sensitive forms) are on the whole but 

 little more prevalent in the raw than in the stored 

 and filtered waters. On the other hand the types 

 corresponding to B. Griinthal, B. vesiculosus, B. cos- 



