MODIFICATION OF TRAITS IN MOSAICS FROM BINUCLEATE EGGS OF 1

Egg blnuclearlty has been suggested to account for the origin o @ a few rare mosaics in Drosophila and of hereditary mosaicism in Ly inantria. Most of the mosaics which have been found in the parasitic wasp, Habrobracon juglandis (Ashmead) , are likewise best explained by this hypothesis. The theory advanced by the writer (Whiting. P. W., 1922) is that after extrusion of the first polar body, the second oöcytenucleus gives rise to two (reduced) nuclei which either take part in parthenogenetic cleavage (male mosaics) or segment after one has been fertilized (gynandromorphs). Post-reduction of binucleate eggs from heterozygous females would then result in mosaic males or, in case of fertilization of one nucleus, in gynandromorphs in which maternal contribution to male and female parts was different. Mosaics in Ilabrobracon are very infrequent. The present paper is based on 132 mosaic males and 92 gynandromorphs which have oc curred scattered through the cultures of various investigators. When ever a mosaic has been reported it has been given a serial number in the “¿freak book†• with a statement of its origin, a description, and any other pertinent data. The specimen, placed in a gelatine capsule, is then preserved in alcohol for future reference. MOSAIC MALES FROM HETEROZYGOUS MOTHERS Virgin females heterozygous for various genes have been bred +jn tests for linkage. Most of the mosaic males have been found in con nection with these studies. They therefore arise from unfertilized eggs and are mosaic for one or more of those traits for which their mothers were heterozygous. It will be convenient first to give a record of these male mosaics as regards the various genes involved. Females heterozygous for orange, o (eyes) (Chromosome I), have produced thirteen sons mosaic for this trait. When tested by matin