Evidence is presented that atypical reactions of Escherichia coli on eosin methylene blue agar are due to variations in pH in localized areas of the medium.

Sporulation of B. anthracis, B. subtilis, B. cereus, B. ruminatus, B. mesentericus, B. anthracoides and B. megatherium does not take place in an agar medium containing eosin "Gelb" in a concentration exceeding 0.5 per cent. In a concentration of 0.1 per cent. most of these bacteria fail to produce spores. The greatest sensitiveness is shown by B. cereus and B. mesentericus. In a bouillon medium...