Abstract
Both red eye (re) and rust eye (ru) are recessive, partially sex-linked, completely penetrant, relatively constant in expression and visible at all stages. The sequence of loci is ru, re and sex. Recombination is highly variable between families, cross types and sex. Recombination involving sex can only occur in the heterogametic male, but recombination between re and ru is 50% greater in males than females. Deficiency of double crossovers suggests chiasma interference with a coefficient of coincidence of 0.14. Relative linkage distances based on males are re to sex: 6.4 [plus or minus] 0.5 ru to sex: 26.4 [plus or minus] 1.1 and ru to re: 22.1 [plus or minus] 1.2.