Genie Control of Development 375 



autosomal modifiers are present in vg/+, only about 1 per cent of 

 the individuals are nicked. The sex-linked modifier alone affects about 

 0.5 per cent of the individuals. But if all three modifiers are present, 

 all vg/-f- heterozygotes are scalloped. ( Blanc, 1946, made it probable 

 that at least two of the modifiers are identical with known mutants, 

 facet and purple.) The modifiers have also an additive effect 



Fig. 20. Action of vg alleles and compounds with and without dominance modi- 

 fiers and related to development. (From Goldschmidt and Honer, 1937.) 



( AA > Aa, AB/AB > AB/ab. Furthermore, the effects are different in 

 the two sexes (see discussion of dosage compensation). We combined 

 many of the alleles and compounds (listed, with their action, on p. 

 373) with a full set of dominance modifiers, and studied the effects 

 upon scalloping quantitatively. The major body of the results is con- 

 densed in a diagram (fig. 20), which simultaneously indicates the ex- 

 planation in terms of figure 18. On the abscissa we find the classes of 



