THE BACTERIA IN NATURAL WATERS 19 



sistence of typhoid and colon bacilli in water, although 

 in nutrient media both forms may thrive under anaerobic 

 conditions. 



EFFECT OF OXYGEN ON VIABTLITY OF TYPHOID BACILLI 

 IN STERILE TAP WATER 



Whipple and Mayer, 1906 



Various inorganic constituents of the medium imdoubt- 

 edly exercise an important influence upon the life of 

 bacteria in water; and the mutual interaction of the 

 different substances present is a highly complex one. 

 Thus Winslow and Lochridge (1906) report that five 

 parts of dissociated hydrogen per million parts of tap 

 water (0.005 normal HCl) is fatal to t\-phoid bacilli, 

 while ten times as much acid is required for sterilization 

 when I per cent of peptone is present to check the 

 dissociation of the hydrogen. In Hazen and WTiipple's 

 study of the Allegheny, Monongahela and Ohio rivers 



