MOSAICISM AND MUTATION INHABROBRACON

Abstract

1. Independent segregation of ivory (eye color) and reduced (wings) is shown in progeny of Oo'Rr females.2. When such females are mated to orange, o, males there occur among the normal offspring, orange (biparental) males with characteristic sterility.3. One female from RR female by r male and one sterile biparental male from rr female by R male were each characterized by possessing one long and one reduced wing. Elimination of chromosome bearing R is suggested as explanation.4. Eight mosaic males were produced by Oo' females. Of these—one was sterile, four produced black daughters only, one ivory only, and two both black and ivory. It is suggested that these males arise from binucleate eggs and that gynandromorphs are produced when one nucleus of such eggs is fertilized.5. Of seven gynandromorphs six showed male parts matroclinous while in one they appeared patroclinous. In the latter case they may have been diploid, comparable to ordinary male biparentalism.6. Two mosaic males had eyes completely orange while four mosaic males and one gynandromorph had eyes mosaic of black and orange. Since presumably only black or ivory entered into the gametes producing these mosaics, the orange color must have been due to some somatic physiological effect or to mutation.7. Three mutant orange males showing no mosaicism and breeding as orange were produced by Oo'Rr females.