BACTERIAL CONTENTS OF VARIOUS WATERS 105 



obvious, therefore, that on pumping being resumed 

 these surfaces will be washed down, and consequently 

 in the first pumping the water will receive a great in- 

 flux of micro-organisms, and it will be only after pump- 

 ing has been going on continuously for some time that 

 a sample representing the bacterial condition of the water 

 gaining access to the well is obtainable. The following 

 example will show the power of multiplication possessed 

 by the organisms in deep-well water. ^ 



Bacterial Contents of Well-ioater before and after standing 

 (Percy Frankland) ■ 



Number of Micro-organisms obtained from 1 c.c. of water 

 Date of April 15, 1886, AprillT, 1886* 



Collection, after standing standing 3 Days 



Description April 14, 1886 for 1 Day at 20° C. at 20° C. 



Kent well sunk into chalk . 7 21 495,000 



Heraeus ^ examined a well-water which had only 

 been very little used during the previous thirty-six 

 hours, and found 5,000 organisms per c.c. ; but after the 

 well was emptied by continuous pumping a second 

 sample was collected, after an interval of half-an-hour,. 

 and only 35 in the c.c. were present. Similar results 

 were also obtained by C. Frankel.^ 

 : Maschek ^ has also shown the effect of pumping on 

 the microbial contents of well-water thus : — 



Effect of Pumping on the Bacterial Contents of Well-water 

 (Maschek) 



Number of Micro-organisms 

 obtained from 1 c.c. of water 



Well-water after continuous pumping for fifteen minutes . 458 



,, •,, „ „ „ many hours . 140 



„ later 68 



„ after continuous pumping for fifteen minutes . 578 



n M „ „ „ many hours . 179 



„ later 73 



^ * On the Multiplication of Micro-organisms,' Percy Frankland, Proc^ 

 Bo2j. Soc, 1886. 



^ ' Ueber das Verhalten der Bacterien im Brunnenwasser,' Zeitsclirift 

 fur Hygiene^ vol. i. 1886, 



^ * Ueber Brunnendesinfectioh u. Keimgehalt des Grundwassers,' ihid* 

 vol. vi. p. 32, 1889. 



* Kuhel-Tiemann- Gartner ' TFctsser,' pp. 576-77. Braunschweig, 1889« 



