BACTERIAL CONTENTS OF VARIOUS WATERS 103 



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. 1 



Bacterial Contents of Well-water before and after standing 

 (Percy Frankland) 



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



Date of April 15, 1886, April 17, 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 2 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 y 

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

 were also obtained by C. Friinkel. 8 



Maschek 4 has also shown the effect of pumping oil 

 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 



,, ,, ,, many hours . 179 



later . 73 



1 ' On the Multiplication of Micro-organisms,' Percy Frankland, Proc. 

 Boy. Soc. 1886. 



2 ' Ueber das Verhalte*n der Bacterien iru Brunnenwasser,' Zeitschrift 

 fur Hygiene, vol. i. 18.86. 



3 ' Ueber Brunnendesinfection u. Keimgehalt des Grundwassers,' ibid. 

 vol. vi. p. 32, 1889. 



4 Kubel-Tiemann-Gdrtner ' TTasser,' pp. 576-77. Braunschweig, 1889. 



