Males deficient for the loci yellow and achaete or for yellow, achaete, and scute were rendered viable by the presence of a duplication which carries these genes and is known to be frequently eliminated during somatic division. Deficient areas, yellow in color, occur on the 6th to 8th abdominal segments, showing that they are not autonomous but are rendered viable by neighboring non-deficient cells. The size of the areas indicates that the deficient cells are able to divide. The absence of the yellow locus is phenotypically like the mutant yellow.