Summary
The association between longevity and resistance to 60Co γ-rays has been examined in four inbred lines of Drosophila melanogaster. Regressions of mean mortality on dose fit both linear and exponential curves. The conclusion from both types of curve is that the resistance, as measured by the slope of the regression, varies between lines and is independent of the longevity of unirradiated flies. Although there was no difference in mean mortality between the two sexes within lines, the two sexes did differ, since the female variance was over twice that of the male variance.