The irradiation of bacterial spores with low-voltage electrons

Abstract

Three regions of radiation sensitivity are found in the spores of Bacillus subtilis. The first two form the spore wall, which is variable in thickness on each spore. The outer layer is completely inert, showing no reaction to radiation; this might correspond to a dried slime layer which is said to surround the spore. An inner spore wall lies within this completely inert layer which shows low sensitivity to ionizing radiation, the effect being cumulative. The total thickness of the two spore coats is less than 350 A. The portion of the spore most sensitive to radiation is organized into units of large molecular weight which are dispersed at random throughout the interior of the spore. No evidence of a single organized nucleus containing the particles of maximum radiation sensitivity is found by this method of investigation.