Triploid intersexes in Drosophila are variable both in external and in internal structures; some are nearly [male]-like, some are similar to normal [female] [female], and others are mixtures of [male] and A characteristics. The chromosomes are, however, similar in all the intersexes. The variability of intersexes is due to the influence of both genetical and environmental factors. By selection, strains were produced giving only the extreme [male]-type or only the extreme [female] -type intersexes. An appropriate genetical analysis showed that these strains are different in respect of some genes located in the 3rd chromosome. These genes do not produce, however, any influence on the sexual characters of normal [female] [female]and [male][male]. Cultures producing intersexes were kept at 15, 20, 24, and 28[degree]. At higher temp. the average type of the intersexes is more [female] -like than at lower temp.