ELECTRON BOMBARDMENT OF BIOLOGICAL MATERIALS

Abstract

The rate of inactivation of spores of Aspergillus niger, when bombarded in vacuum with homogeneous beams of cathode rays of energies from 4-15 electron kv. and current densities of 1 X 10-7 to 3 X 10-6 amps. per sq. cm., was investigated. These velocities and densities were selected because they are in the range of those showers of secondary electrons produced in biol. materials irradiated with moderately soft X-rays, and so may be made to serve as quantitative indicators of the mechanics of X-ray action. 4 distinct effects were found: a distinct shortening of germination time was observed at very low voltage; germination became very irregular at voltages from 11-15 kv. and cultures from these spores showed several mutations; marked retardation of growth; and complete inactivation. The last effect is reported on in detail.