APPENDIX 361 



VII. Dunham's solution; twenty-five tubes for each stu- 

 dent. (See p. 43.) 



VIII. Nitrate peptone solution; twenty-five tubes for 

 each student. (See p. 44.) 



IX. Litmus milk; twenty-five tubes for each student. 

 (See p. 25.) 



EXPLANATION OF TABLE ON PAGES 362-363 



Method. B. coli- and B. cholerce suis-like organisms: 

 Place 5 c.c. of suspected water in each dextrose and liver 

 broth fermentation tube and 50 to 100 c.c. in a litmus lactose 

 agar flask. Incubate at 37 C. If gas appears in time of 

 three days, make plating on Conrad-Drigalski's agar * from 

 one showing most of gas production. Isolate different 

 colonies on agar slants. From the growth on the agar 

 slants inoculate different media to subgroup the organisms 

 and consequently to identify them. 



B. typhosus: Hoffman and Fiske enrichment medium. 

 Add to the suspected water 1.0% of nutrose; 0.5% of 

 caffein; 0.001% of crystal violet. Incubate at 37 C. 

 for not more than twelve to thirteen hours. Make Endo 

 or Conradi-Drigalski agar plates. Isolate bluish colonies, 

 transferring to agar slant, and identify. The Widal reac- 

 tion should be used for the confirmatory test. 



(Data on pages 362-363 collected by 0. M. Gruzit.) 



* Other media for bacteriological water analyses will be found in 

 the 1915 edition of the " Standard Methods for the Examination of 

 Water and Sewage " published by the American Public Health Associ- 

 tion, pp. 124-137. 



This publication is the standard work; references to special phases 

 will be found in the bibliography following each chapter. 



