124 ELEMENTS OF WATER BACTERIOLOGY 



5000 samples of water at the Mt. Prospect Laboratory, 

 the bile medium has proved uniformly satisfactory. 

 He recommends incubation for 72 hours, results being 

 commonly obtained, however, after 48 hours; and he 

 considers any tube showing 25 per cent gas as positive. 

 In a series of examinations carried out at the Institute 

 of Technology, 16 per cent of the positive tubes showed 



COMPARATIVE PRESUMPTIVE TESTS WITH DEXTROSE 

 BROTH AND LACTOSE BILE 



(SAWIN, 1907) 



