Transvection effects in Drosophila melanogaster suggest a form of gene modulation that is responsive to the proximity of homologous genes. These effects have been well characterized at bithorax and decapentaplegic, and in the interaction between the zeste and white genes. The mechanistic basis for transvection is not known. As part of a genetic analysis of transvection, a study is being made of a class of mutations defined as modifiers of the eye color resulting from the interaction of zeste and white. This report details the observations that several of these mutations also have homeotic effects.