Further studies on heterozygous effects of radiation on viability of Drosophila melanogaster.

Drosophila second chromosomes which had received a dose of 1000 R of X-rays were studied for heterozygous effects of newly-induced mutations on viability. In both homozygous and heterozygous backgrounds, the mean effect of radiation was not significantly different from zero. The results, therefore, do not support the experiments of Wallace and Mukai nor those reported by Maruyama and Crow.