Tritium-Induced Effects in Paramecium Aurelia

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Abstract
Effects induced by metabolized radioactive hydrogen (tritium or T) and presumed to be genetic in nature have been measured in P. aurelia. Organisms were allowed to divide 6-8 times during 2 days in culture fluid containing T in concns. varying from 1 to 100 mc per ml. With increasing radioactivity of the medium, increasing death after autogamy was observed, but no preautogamous effects were noted. The response observed after exposure to T appears to be slightly lower than induced by emitters of more energetic beta particles at similar dosage levels. The conclusions are that no part of the effect can be ascribed to transmutation of T, the emitted electrons alone apparently inducing the biological changes; and that the difference in efficiency between T and Sr89 90Y90 is consistent with the observations of others concerning the dependence of the mutation constant upon rate of energy loss by densely ionizing particles.