104 ELEMENTS OF WATER BACTERIOLOGY. 



TABLE II. 



RELATIVE GROWTH OF B. COLI AND SEWAGE STREPTOCOCCI FROM 



POLLUTED WATERS IN DEXTROSE BROTH. 



(Prescott and Baker, 1904.) 



litmus-lactose-agar in the usual way, and incubated for 

 twenty- four hours. The colonies of B. coli and strep- 

 tococci were distinguished microscopically, and by differ- 

 ence in color and general characters. 



These facts suggest the following method for the detec- 

 tion of B. coli and sewage streptococci in polluted waters. 



Inoculate the desired quantity of water, preferably i c.c., 

 into dextrose broth, in a fermentation-tube, and incubate 

 at 37. After a few hours' incubation examine the cul- 

 tures for gas. Within two or three hours after gas for- 

 mation is first evident, plate from the broth in litmus- 

 lactose-agar, incubating for twelve to eighteen hours at 



