Genic and Nongenic Transmission of Mutator Activity.

HE present study is based on the analysis of the recessive mutator gene T (MAMPELL 1945). This mutator is located to the right of cinnabar in the second chromosome of Drosophila pseudoobscura, race B (D. persimilis Dobzhansky and Epling). When males are homozygous for this gene, mutations (usually belonging to the “Minute” phenotype) are induced in those males as well as in their offspring, no matter whether their offspring are male or female, homozygous or heterozygous. When females are homozygous for this gene, no such effects are observed. It has been assumed that homozygous mutator males produce a substance which induces the mutations; this substance would be transmitted to all the offspring through the cytoplasm of the sperm. The heterozygous males or homozygous wild type males would produce the wild type counterpart to the substance (insuring the stability of the genes) which would be transmitted in the same manner as the mutator substance.