128 



Elements of Water Bacteriology. 



PRESENCE OF B. COLI IN POLLUTED AND UNPOLLUTED 



WATERS. 



(WINSLOW AND HUNNEWELL, ipo2b.) 



ITnpolluted Waters. 



I c.c. zoo C.C. 



Samples examined . . 

 iDextrose broth positive 

 Lactose plate positive . 



Colon group 



Paracolon group . 



B. cloacas group . . . 



Streptococcus group . . 



iS7 

 40 



13 



S 

 S 



IS3 

 76 



31 

 II 



s 



s 



10 



Polluted Waters. 



Samples examined . . 

 Dextrose broth positive 

 Lactose plate positive . 

 Colon group . 

 Paracolon group . . . 

 Streptococcus group 

 B. cloacae 



48 



37 

 26 



4 



As the authors pointed out, these tables indicate that 

 bacteria capable of growth at the body temperature and 

 fermenting dextrose and lactose are infrequently found in 

 unpolluted waters, and colon bacilli are very rarely present. 

 In 157 samples, typical colon bacilli were found only 5 

 times out of 157, in i c.c. Lactose fermenting organisms 

 appeared in only 8 per cent of the normal samples and in 

 ];oo per cent of the polluted ones, in i c.c. Incidentally 

 it may be pointed out that these tables well illustrate the 

 dangers of overgrowths, particularly in large samples. It 



