Qiiantitative Bacteriological Examination. 33 



is reached. The student will find one good form of 

 apparatus described in Abbott's "Principles of Bacteri- 

 ology" (Abbott, 1899); an admirable one was devised 

 by Hill and EUms (Hill and Ellms, 1898); and Thresh 

 (1904) figures an ingenious device for the same pmrpose. 

 Miquel and Cambier (Miquel and Cambier, 1902) and 

 other authors recommend the use of a sealed glass bulb 

 with a capillary tube which can be broken off at the 

 desired moment. 



As soon as a sample of water is collected, its conditions 

 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 amoimt of organic matter is infinitesimal, enormous 

 numbers may be found after storage under laboratory 

 conditions for a few days or even a few hoiu:s. 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 three days. Miquel (Miquel, 1891) 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 tempera- 

 ture, and a destruction of higher micro-organisms is 

 responsible for the increase, and to what extent an exhaus- 

 tion of food-supply or the formation of toxic waste 



