QUANTITATIVE EXAMINATION OF WATER 37 



of equilibrium are upset and a change in the bacterial 

 content begins. Even in the purest spring-waters, 

 which contain but few bacteria when collected, and in 

 which the amount of organic matter is infinitesimal, 

 enormous numbers may be found after storage under 

 laboratory conditions for a few days or even a few hours. 

 In some cases the rise in numbers is gradual, in others 

 very rapid. The Franklands (Frankland, 1894) record 

 the case of a deep-weU water in which the bacteria 

 increased from 7 to 495,000 in 3 days. Miquel (^liquel, 

 1 891) from his researches, arrived at the conclusion 

 that in surface-waters the rise is less rapid than in waters 

 from deep wells or springs, and that in the latter case 

 the decrease, after reaching a maximum, is likewise 

 rapid and steady. Just how far protection from light, 

 increase in temperature, and a destruction of higher 

 micro-organisms is responsible for the increase, and 

 to what extent an exhaustion of food-supply or the 

 formation of toxic waste products causes the succeeding 

 decrease, we are not aware; but the facts are well 

 established. 



Whipple has exhaustively studied the details of 

 this multiplication of bacteria in stored waters 

 and has shown in the table given below that 

 there is first a shght reduction in the number 

 present, lasting perhaps for 6 hours; followed by 

 the great increase noted by earlier observers. It 

 is probable that there is a constant increase of the 

 typical water bacilli, overbalanced at first by a 

 reduction in other forms, for which the environment 

 is unsuitable. 



