Phenotypic effects of heterozygous, x-rayinduced mutations in Drosophila.

Heterozygous mutations produced by 3000 r delay pupation in about 9 percent of larvae of Drosophila melanogaster under nutritional stress and kill approximately 6 percent. The effects are less, though appreciable, when there is excess nutrient; no effects are detectable after oögonia are irradiated. Irradiated sperm and oöcytes cause detriment, partly via different types of mutations, in approximately equal amounts.