Standard methods for the examination of water and sewage

by American Public Health Association. Laboratory Section; American Chemical Society; Association of Official Agricultural Chemists

2. If no typical B. coli colonies are found, incubate the plates another 24 hours.

Fifth Day:

1. Select at least two colonies, whether typical or not, from the Endo’s medium or lactose-litmus-agar plates which have been incubated an additional 24 hours; transfer each to a lactose broth fermentation tube and an agar slant, and complete the test as for typical colonies.

2. Examine lactose broth fermentation tubes inoculated from plates on the previous day. Tubes in which gas has been formed may be discarded after the result has been recorded. Those in which no gas has formed should be incubated an additional 24 hours.

Sixth Day:

1. Examine lactose broth fermentation tubes reincubated the previous day.

2. Examine microscopically agar slants corresponding to lactose fermentation tubes inoculated from plate colonies and showing gas-formation.

BACTERIOLOGICAL BIBLIOGRAPHY.

[201]. Bovie, W. T. A Direct Reading Potentiometer for Measuring and Recording both the Actual and the Total Reaction of Solutions. Jour. Med. Research, 33, 1915–16, 295.

[202]. Breed, R. S. and Dotterrer, W. D. The Number of Colonies Allowable on Satisfactory Agar Plates. Jour. of Bact., 1, 1916, 321.