BACTERIAL CONTENTS OF VARIOUS WATERS 99 



above and below Wlirzburg, with the following re- 

 sults : 



Bacterial Composition of the River Main above and below 

 Wilrzburg (Eosenberg) 



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



February 



Above Below 



520 . . . 15,500 



355 . . . 2,950 



680 . . . 16,000 



780 . . . 6,600 



March 



Above Below 



740 . . . 17,000 



830 . . . 13,500 



2,050 . ,' , 9,500 



610 . . . 7,100 



640 . . . 6,400 910 . . . 23,000 



720 . . . 18,000 

 565 . . . 17,200 



640 . . . 35,000 

 950 . . . 11,500 



1,020 . . . 14,000 800 . . . 18,500 



680 . . . 22,000 

 March 



525 . . . 17,000 

 385 . . . 16,200 

 750 . . 15,000 



680 . . . 15,000 830 . . . 19,000 



The river Neva, within St. Petersburg, was found 

 by Poehl 1 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 2 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 



1 Mittheihingen aus dem physiol. chemischen Labor atorium zu St. 

 Petersburg, part I., 1884. 



2 Zeitschrift fur Hygiene, vol. ix. p. 282. 



H 2 



