218 MICRO-ORGANISMS IN WATER 



Number of Micro-organisms 

 Hours in 1 c.c. of water 



1,073 



6,028 



24 7,262 



48 .. ... 48,100 



Thus an enormous multiplication of the bacteria 

 introduced was found to take place in distilled water in 

 which the amount of organic matter present must have 

 been quite a vanishing quantity. 



Leone ' published in the following year some obser- 

 vations on the effect of preserving the Mangfall water 

 supplied to Munich in sterilised flasks and examining 

 the sample on successive days. The results obtained 

 were : 



Number of Micro-organisms 

 in 1 c.c. of water 



Water at time of collection contained ... 5 



Ditto after standing 24 hours in sterilised flask . 100 



2 days . 10,500 



3 67,000 



4 315,000 



5 more than million 



In these and in similar experiments conducted by 

 Meade Bolton and Heraeus 2 an enormous increase in 

 the number of micro-organisms is seen to take place 

 during the period over which the observations extended. 

 Cramer 3 examined, however, some samples of water 

 from the Lake of Zurich after they had been standing 

 for different periods of time up to 70 days, and made 

 the important discovery that, although at first the 

 bacteria multiply extensively, a point is reached when 

 the numbers begin to decline, thus : 



1 Leone, ' Sui microorganism! delle acque potabili ; loro vita nelle 

 acque carboniche.' Archiv fur Hygiene, 4 Band, 2 Heft, 1886, p. 168. 



' Ueber das Verhalten der Bacterien im Brunnenwasser,' ZcUschrift 

 fur Hygiene, vol. i. p. 208, 1886. 



;i Die Wccsserversorgung von Zilricli und ilir Zusamincnliang uiit der 

 Typliusepidemie des Jalires 1884, Ziirich, 1885, p. 91. 



