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) 



