The Limits of the Target Theory of the Biological Action of Radiation

Abstract

The effects of X-radiation on seeds and pollen are markedly reduced when irradiation is carried out at the temp, of liquid air. Cooling the biological objects to this temp, after irradiation at room temp, did not reduce the damage obtained without such cooling. It is concluded that the temp. -dependent effects take place in a very short time and are primarily due to diffusion processes. It follows that the effective sensitive volume is increased by these diffusion processes to many times the volume of the biological structure affected by the radiation.