BACTERIAL CONTENTS OF VARIOUS WATERS 99 



■ .above and below Wilrzburg, with the following re- 

 sults : — 



Bacterial Composition of the Biver Main above and below 



Wilrzburg (Rosenberg") 



Number of Micro-organisms contained in 1 c.c. of water 



February 



March 



March 



680 



15,000 



The river Neva, within St. Petersburg, was found 

 by PoehP to contain in September, 1883, 1,500; in 

 October, 312 ; later in October, 1,524 ; in November, 

 6,500 ; later in November, 3,146. The Little Neva 

 contained, when examined in September, 4,836 ; in 

 October, 5,772. 



Tils ^ has made an exhaustive investigation of the 

 Freiburg water supply, the main part of which is de- 

 rived from a mountain-stream, which is conveyed to a 

 reservoir, from whence pipes distribute it to the town. 

 It was found that bacterially the water was purer when 

 examined from the reservoir than when taken at the 

 source, showing that here, again, the sedimentation of 

 bacteria takes place. Taking the average of a large 

 number of experiments, the supply derived from the 

 reservoir was found to contain twelve organisms in the 

 cubic centimetre, whilst the same water, after passing 



^ Mittheilungen aus dem physiol. chemischen Lahoratoriu7n zu St. 

 JPetershurg, part I., 1884. 



^ Zeitschrift filr Hygiene^ vol. ix. p. 282. 



H 2 



