217 



CHAPTEE VI 



ON THE MULTIPLICATION OF MICRO-ORGANISMS 



One of the first difiiculties whicli 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 

 water itself. 



One of the first recorded observations on this subject 

 was made by one of us ^ 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 : — 



^ ' Kemoval of Micro-organisms from Water,' Percy Frankland. Proc. 

 Boy. Soc. 1885. 



