SIGNIFICANCE OF COLON GROUP IN WATER 159 



The river at the lower stations in this table was con- 

 siderably diluted with sea-water, yet it showed clearly 

 its large proportion of sewage. Normal sea- water, 

 even in the neighborhood of the shore, shows, B. coli 

 only in large samples. Houston (1904), in another 

 communication, reports the examination of 168 samples 

 of sea- water near the English coast. None of the samples 

 showed B. coli in i c.c.; 97 samples gave negative 

 results in 10 c.c.; 45 in 100 c.c., and 4 had no B. coli 

 even in 1000 c.c. 



B. COLI IN THE RIVER THAMES AT VARIOUS POINTS 



(HOUSTON, i904 a ) 

 Percentage of Positive Results 



Gartner (1910) has collected some interesting data 

 in regard to the ratio between the number of colon 

 bacilli and of total bacteria in waters of different 

 quality. The results from four different sets of experi- 

 ments by Konrich at Jena, Houston at London, Noble 

 in New York, and Hill at Giessen, may be combined 

 as on the opposite page: 



