Some results and interpretations of X-Irradiation studies with Escherichia coli

1. 1. The protection afforded E. coli B/r by incubation with succinate at 37 ° for 30 min. before exposure to x-irradiation could not be demonstrated except under conditions which prevented the equilibration of oxygen dissolved in the bacterial suspension with the oxygen of the air. 2. 2. Protection of E. coli B/r cells with 0.2 M ethanol could be demonstrated under conditions which did not permit succinate protection even though suspensions with succinate consumed greater quantities of oxygen per unit time than suspensions with ethanol. 3. 3. Irradiated suspension of E. coli B/r showed no dilution effect; a given irradiation dose resulted in essentially the same percentage inactivation for suspensions containing from 10 4 to 10 9 cells/ml. 4. 4. These findings are evaluated and the interpretations of the effects of ionizing radiation relevant to physical experimentation are discussed.