DEVELOPMENT OF EYE COLORS IN DROSOPHILA: FAT BODIES AND MALPIGHIAN TUBES IN RELATION TO DIFFUSIBLE SUBSTANCES

Abstract

T HAS been shown that diffusible substances are involved in the differI entiation of certain eye colors in Drosophila melanogaster (EPHRUSSI and BEADLE 1937a; BEADLE and EPHRUSSI 1937). Fat bodies are concerned with the production of one of these substances (v+ substance); two substances (v+ and cn+ substances) can be obtained from the Malpighian tubes of flies of certain genotypes. Preliminary experiments having to do with fat bodies and Malpighian tubes have been reported (BEADLE 1937a). It is the purpose of this paper to report more extensive studies of the relation of fat bodies and Malpighian tubes to eye color development. In particular, tests of fat bodies and Malpighian tubes of various eye color mutant types are reported. Certain experiments have been directed toward determining whether Malpighian tubes produce the substances obtainable from them or, on the other hand, whether these substances are produced in other parts of the body and are merely taken up by Malpighian tubes. Certain results bear on the question whether flies of certain constitutions, cinnabar for example, are characterized by complete absence of certain diffusible substances, cn+ substance in the case of the cinnabar fly, or merely by what might be called sub-threshold concentrations.