THE MULTIPLICATION OF MICKO-OIIGANISMS 235 



rapid decline in the case of the water kept at 19° C, 

 less rapid and followed by a much less rapid decline 

 in the case of that kept at 8"" C Thus the bacteria 

 in the water maintained at 19° C. must have attained 

 their maximum and fallen to 45,000 per 1 c.c. during 

 the first six days, whilst the bacteria in the water kept 

 at 8° C. still numbered 560,000 on the sixth day, but 

 had fallen to 166,000 and 58,000 on the twelfth and 

 nineteenth days respectively. 



The results obtained with the Loch Katrine water 

 on p. 230 similarly point to the comparatively restricted 

 multiplication taking place in full stoppered bottles. 



In this connection we may quote some incidental 

 remarks of Wolffhilgel and Eiedel, ^ which indicate that 

 they also observed some differences in the multiplication 

 of bacteria in tightly stoppered bottles and in those 

 plugged with cotton- wool respectively : — 



' This diminution ^ in the number of micro-organisms 

 in water takes place, as was proved by comparative 

 experiments, in vessels plugged with cotton- wool as well 

 as in those closed with india-rubber corks. On the other 

 hand, it was almost generally found that in the vessels 

 closed with india-rubber corks somewhat less multiplica- 

 tion of the bacteria took place than in those in which 

 cotton-wool plugs were employed. The apparently 

 more flourishing condition of the micro-organism in the 

 latter vessels may possibly be due to the interchange of 

 air beftig less restricted than is the case with the former.' 



Multiplication of bacteria in carbonated ivaters. — 

 This restricted multiplication, which apparently takes 

 place when the supply of air to the water is limited, 

 naturally leads us to a consideration of the case of those 



* * Die Vennelirung der Bacterien im Wasser,' Aroeiten a. d. 'kaiser- 

 lichen Gesundheitsatnte, vol. i., 1886, p. 463. 



^ Observed when samples of water were exposed to a low temperature- 



