BACTERIA IN WATER. 643 



of the Panke, 940,000; below the mouth of the Panke, 1,800,000 

 (Koch). 



Water of the Main above the city of Wiirzburg, in the month of 

 February, 520 ; below the city, 15,500 (Rosenberg). 



Water of the Potomac, at Washington, in 1886 : January, 3,774 ; 

 February, 2,536; March, 1,210; April, 1,521; May, 1,064; June, 

 348 ; July, 255 ; August, 254 ; September, 178 ; October, 75 ; No- 

 vember, 116 ; December, 967 (Theobald Smith). 



The Thames, in the autumn of 1885, in the vicinity of London 

 Bridge two hours after high water, contained 45,000 germs per cubic 

 centimetre ; the water of the Lea at Lea Bridge, 4,200,000 (Bisch- 

 off). 



The Neva inside the city of St. Petersburg, in September, 1883, 

 contained 1,500 in one sample and 1,040 in another ; in November 

 (20th), 6,500 (Poehl). 



The water of the Oder, collected within the limits of the city of 

 Stettin, was found by Link to contain from 5,240 to 15,000 bacteria 

 per cubic centimetre ; that of the Limmat, at Zurich, 346 in one 

 specimen and 508 in another (Cramer). 



Lake water, as a rule, contains fewer bacteria than river water. 



Wolffhiigel, in researches extending from July, 1884, to July, 

 1885, obtained from the water of the Tegeler Lake an average of 396 

 bacteria per cubic centimetre. Cramer obtained an average of 168 

 per cubic centimetre during the months of October, December, and 

 January, 1884, from the water of Lake Zurich ; in June of the same 

 year the average of 42 examinations gave 71 per cubic centimetre. 

 In Lake Geneva, Fol and Dunant obtained from water collected some 

 distance from the shore an average of 38 bacteria per cubic centi- 

 metre. 



Ice which is usually collected from lakes and rivers contains a 

 greater or less number of bacteria, according to the depth and purity 

 of the water. The ice used in Berlin, collected from the surface of 

 lakes and rivers in the vicinity of the city, contains from a few hun- 

 dred to 25,000 bacteria to the cubic centimetre (Friinkel). In the ex- 

 periments of Heyroth samples of ice from the same source gave less 

 than 100 per cubic centimetre in three, from 100 to 500 in eight, from 

 500 to 1,000 in six, from 1,000 to 5,000 in seven, and 14,400 in one. 



Prudden obtained from Hudson River ice, put up six miles below 

 the city of Albany, an average of 398 bacteria per cubic centimetre 

 from transparent ice, and in the superficial "snow ice" 9,187. Ice 

 collected lower down the river contained an average of 189 in the 

 transparent and 3,693 in the snow ice. 



Ice from the Dora at Turin was found by Bordoni-Uffreduzzi to 

 contain from 120 to 3,546 bacteria per cubic centimetre. 



