A Comparison of the Action of X and Gamma Radiation on Fibroblasts—Part II

Using cultures of fibroblasts irradiated on glass and on other materials, no qualitative differences in the effect of X and γ rays can be shown in the growth of such cultures in the period which elapses between irradiation and death. The possible mechanism of death and of recovery of cultures is discussed. 2. A quantitative difference, shown in the death rates, exists in the effect of X and of γ rays on cultures irradiated on glass or on gold, in the direction of X rays being more lethal. 3. No significant difference between X and γ rays could be demonstrated when cultures were irradiated on certain light materials. 4. The effect of X rays is decreased when cultures are irradiated on light materials in contrast with materials containing atoms of medium or of high atomic number. 5. The experimental evidence supports the belief that observed differences between the effects of γ rays and of X rays in equal doses may be at least in part explained by the quantitative variation in secondary electronic emission which depends on the substances in intimate relationship with the cells.