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A MANUAL OF BACTERIOLOGY 



Average Number of Microbes per c.c. in London Raiv Waters. 



Gelatin at 20-22 C. ; Counted on the third day. Agar and Neutral 

 red bile-salt lactose Agar at 37 C. Counted after twenty to twenty-four 

 hours. 



Average Number of Microbes per c.c. in London Filtered 



Waters. 

 (Exclusive of Samples containing 100 or more Microbes per c.o.) 



(Gelatin at 20-22 C. ; counted on the third day. Agar and Neutral 

 red bile-salt Agar at 37 C. Counted after twenty to twenty-four hours. 



1 All of these samples were tested by each of the three tests (gelatin, 

 agar and bile-salt agar). 



- Gelatin, ten years' average, 1906-16 : agar, six years' .-rvcfauc, 191 0-1(5 ; 

 bile-salt agar, three years, 1913-16. 



