THE MULTIPLICATION OF MICEO-ORGANISMS 219 



] Miquel ^ has extended these observations m an in-i 

 teresting manner by keeping a bottle of river Seinel 

 water shut up for nine years, and whilst at the time of 

 collection 4,800 bacteria per c.c. were found, at the 

 end of the nine years there were only 220 discoverable. 

 Again, a sample of Vanne water, containing at the time 

 of collection 66 organisms per c.c, at the end of 10 

 years was found to be absolutely sterile. 



In 1886 a systematic series of experiments on the 

 multiplication of micro-organisms was carried out by 

 one of us ^ in this countrj^, and by Meade Bolton ^ in 

 Germany. 



, The waters experimented with in the first-mentioned 

 series of investigations were the raw river- waters of 

 the Thames collected at Hampton, and of the Lea at 

 Chingford, as well as the same waters after sand-filtra- 

 tion, and as distributed by the water companies to 

 London, besides the deep-well M^ater derived from the 

 chalk. 



As we have already seen, the bacterial composition 

 of these various waters is very different, and hence it 

 was expected that the phenomenon of multiplication 

 would likewise show marked deviations in the case of 

 each class of water. 



' Eevue d'Hygiene, torn. ix. p. 737. 



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

 Boy, Soc. 1886. 



^ * Ueber das Verhalten verschiedener Bacterienarten im Trink- 

 wasser,' Zeitschrift f'nr Hygiene, 1886, vol. i. 



