QUANTITATIVE BACTERIOLOGICAL ANALYSIS. 39 



Streams receiving direct sewage pollution exhibit a simi- 

 lar excess of bacteria at all times, numbers rising to an 

 extraordinary height near the point of entrance and fall- 

 ing off below as the stream suffers dilution and the sewage 

 organisms perish. Miquel (Miquel, 1886) records 300 

 bacteria per c.c. in the water of the Seine at Choisy, above 

 Paris, 1200 at Bercy in the vicinity of the city, and 200,000 

 at St. Denis after the entrance of the drainage of the city. 

 Prausnitz (Prausnitz, 1890) found 531 bacteria per c.c. 

 in the Isar above Munich, 227,369 near the entrance of 

 the principal sewer, 91 n a': a place 13 kilometers below 

 the city, and 2378 at Freising, 20 kilometers further 

 down. Jordan (Jordan, 1900), in his study of the fate of 

 the sewage of Chicago, found 1,245,000 bacteria per c.c. 

 in the drainage canal at Bridgeport, 650,000 twenty-nine 

 miles below at Lockport, and numbers steadily decreasing 

 below to 3660 at Averyville, 159 miles below the point of 

 original pollution. Below Averyville the sewage of Peoria 

 enters and the numbers rise to 758,000 at Wesley City, 

 decreasing to 4800 in 123 miles flow to Kampsville. 



In ground-waters we have seen that bacteria may be 

 present in considerable numbers, but that they will 

 generally be organisms of a peculiar character, incapable 

 of development on the ordinary nutrient media in the 

 standard time. Thus in forty-eight hours we often obtain 

 counts measured only in units or tens. When higher 

 numbers are present, the general character of the colonies 

 must be taken into account, since besides the slowly- 

 growing forms certain other water bacteria which 



