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CHAPTER VI 



ON THE MULTIPLICATION OF MICEO-OEGANISMS 



ONE of the first difficulties which the water-bacterio- 

 logist had to encounter was the discovery that if any 

 considerable interval is permitted to elapse between the 

 collection of a sample of water and its subsequent ex- 

 amination, the number of bacteria present is generally 

 found to have undergone extensive multiplication. This 

 disturbing factor in the accurate appreciation of the 

 normal bacterial contents of a given water was not 

 discovered until some time after the introduction and 

 application of Koch's gelatine-plate process to the in- 

 vestigation of water ; indeed, it was not unnaturally a 

 matter of great surprise to find that some micro- 

 organisms are capable of multiplying largely in waters 

 of great organic purity, and even in ordinary distilled 

 w T ater itself. 



One of the first recorded observations on this subject 

 was made by one of us l in 1885. Three sterilised Win- 

 chester bottles were filled with ordinary distilled water, 

 and a few drops of diluted urine water added ; the 

 bottles were then plugged with sterilised cotton-wool, 

 placed in a room (temperature about 10 C.) and left 

 at perfect rest. The following were the results ob- 

 tained : 



1 ' Removal of Micro-organisms from Water,' Percy Frankland. Proc. 

 Boy. Soc. 1885. 



