Sections of the Xple chromosome (scute, echinus, cross-veinless, cut, vermilion, garnet, forked) designated by the mutant genes were added to low selected forked Bar singly and cumulatively in the left-right direction and also in the right-left direction on the chromosome. Analysis of the facet counts of the [male][male] of 15 different combinations raised at 25[degree] C. shows that the cut and garnet sections are strong minus modifiers of facet number, the others are plus modifiers, vermilion and cross-veinless notably so, when referred to forked Bar as base. When the mutant genes are added cumulatively in the left-right direction on the chromosome, Bar eye becomes progressively larger until garnet is added. In Xple Bar, the eye is slightly but not significantly larger than in forked Bar. When sections of the Xple chromosome are added to forked Bar in the right-left direction on the chromosome, the eye is smaller than in forked Bar, but becomes progressively larger. The logarithm of the number of facets in the dorsal ([chi]) lobe is directly proportional to the number of facets in the ventral lobe(y) of the eye, that is y=bxk. As increases in arithmetical progression, b decreases in geometrical progression according to the relation b=47e[image]iik.