BACTERIAL CONTENTS OF VARIOUS WATERS 



97 



We have gathered together the results in the fol- 

 lowing table : — 



Table showing Bacterial Composition of the Biver Limmat before and 

 after it receives the Drainage of Zilrich (Schlatter) 



' Rain had fallen on the previous day. 



= Snow had fallen in the morning. The samples 2, 3, 4, were collected from on board a boat in the 

 afternoon. 



^ Thaw had set in. * Snow had faUen on the previous day. 



'^ Snowstorm in the morning previous to taking of sample. "^ Slight fall o£ snow on previous day. 



' Thaw and slight fall of snow. ' Thaw. " Thaw. Snow over-night, rain the day before. 



'" Snow over-night and in the morning. 



" River-navigation works were being carried on above Dietikon. '■' Rain. 



The average number of micro-organisms in the 

 water from the Lake of Zurich is from 100 to 200 in 

 the c.c. The river Limmat flows out of the lake, and the 

 samples collected below Zurich and after it has passed 

 through the city, but before it receives its drainage, 

 show that already in its flow through Zurich it has 

 become more or less contaminated. The increase in 

 the number of bacteria is, however, very much more 

 marked below the point of the sewage outfall, and after 



H 



