In short, testis size in F1 hybrids is determined by an interaction between the chromosome complement and the cytoplasm. We are dealing either with a real cytoplasmic effect (determination by the intrinsic properties of the cytoplasm, independent of the chromosomes it carries or carried), or with a maternal effect (determination of the properties of the cytoplasm by those of the chromosomes it ...

Eggs from an ebony stock exposed to 5-5 degrees C prior to syngamy exhibited increased production of genetic mosaics in comparison with untreated eggs from the same females. No increase in mosaic production occurred for cold-shocked cleavage-stage embryos from the ebony stock or from pre-cleavage cold-shocked eggs from a wild-type stock. Heat shock of pre-syngamy eggs also failed to increase th...

Goldschmidt, R. B., "Position Effect and the Theory of the Corpuscular Gene," Experientia, 2, 1-40 (1945). Green, M. M., and Green, K. C., "Crossing Over Between Alleles at the Lozenge Locus in Drosophila Melanogaster," PROC. NATL. AcAD. Sci., 35, 586-591 (1949). Komai, T., and Takaku, T., "A Study on the Closely Linked Genes, Miniature and Dusky in Drosophila Virilis, with Some Considerations ...

H E PARASITIC wasp, Habrobracon, has been considered of special T value in connection with studies of dominant lethals because of its somewhat exceptional method of breeding. In “out-crosses,” now called three-allele crosses because they involve triple alleles a t the sex locus, all fertilized eggs develop into females, unfertilized ones into males (WHITING 1937a, 1940, 1943). It follows, then,...

N some respects, the mutagenic action of the mustards on Drosophila resembles I that of X-rays. Both are nonspecific in their effects (AUERBACH and ROBSON 1946), each induces an approximate five-to-one ratio of recessive lethals to visible deletions (SLYZINSKA and SLYZINSKI 1947), the same stage of spermatogenesis appears to be sensitive to both mutagens (AUERBACH 1953) and breaks are induced a...