Intersex Modifying Genes in Wild Strains of Drosophila Melanogaster.

HE sex determining mechanism in diploid Drosophila melanogaster is T completely stable. No intersexual individuals are produced from hybridizing strains of D. melanogaster collected from widely separated geographical localities. In Lymantria, on the contrary, GOLDSCHMIDT (1934) has shown that the potencies of the X chromosome sex gene differs in races from Europe and Japan. The degree of sexuality in triploid intersexes (2X 3A) of D. melanogaster in contrast to the diploid sexes is remarkably sensitive to both genetic and environmental mileu (DOBZHANSKY 1930). DOBZHANSKY found that temperature affected the sex type of intersexes. The same author demonstrated the presence of modifying genes in a triploid strain. By means of several generations of selection, he derived a triploid strain producing predominantly male-like intersexes and also a triploid strain producing predominantly female-like intersexes. DOBZHANSKY located intersex modifying genes in chromosome I11 capable of shifting the intersex sex type when present in only one dose. The purpose of the present paper is to determine whether or not different intersex modifying genes located in the X chromosome exist in wild populations of Drosophila collected from various geographical regions. /