A Comparison of the Diffusible Substances Concerned with Eye Color Development in Drosophila, Ephestia and Habrobracon

Diffusible substances have been postulated as being concerned in eye color development in insects belonging to three orders, Ephestial and Bombyx (Lepidoptera), Drosophila3 (Diptera) and Habrobracon (Hymenoptera). It is known that the substances concerned in Ephestia and Drosophila are not species-specific.6'6 It is a matter of some interest to determine the relation to one another of the hormones or hormone-like substances in these insects. For example, is the "A-hormone" of Ephestia identical with either "v^+ substance" or cn^+ substance of Drosophila? In connection with this example, Ephrussi has given a comparative summary of the information concerning the A-hormone of Ephestia and the diffusible substances of Drosophila. In the present communication tests of Ephestia for substances active in Drosophila are reported; other experiments planned to show the relation between substances present in Drosophila and those in Habrobracon are described.