272 J. K. BREITENBECHER. 



The above series of experiments prove that the two elytra 

 traits, normal and macula, differ in the male phenotypes only, 

 since the factors for the macula (MM) mutation and the wild 

 (mm) type appear identical for both female traits. These 

 females are alike phenotypically but deviate genotypically, since 

 the normal female has the same black four spotted pattern as 

 its mutant, the macula female. Again, normal is recessive to 

 macula. 



Many sex-differences are detected in insects, occurring most 

 frequently in Diptera; Drosophila probably furnishing the 

 greatest number, with Lepidotera next, then Coleoptera. This 

 sequence appears, as the result of the amount of genetic study 

 directed upon these species. Many of the sex-limited traits in 

 Drosphila are less distinct in one sex than in the other, thus 

 differing somewhat from Bruchus, in which there is no visible 

 manifestation of such characters in the male, except for the 

 macula mutation. 



Examples of these sex-limited traits for Bruchus, in which the 

 male elytra is a non-spotted tan, have been previously demon- 

 strated, hence they will be merely mentioned in this relation. 

 The first mutations discovered (Breitenbecher, 1921) consisted 

 of red, black, white, and tan elytra colors apparent only in the 

 females. The respective male for each of these four female 

 cultures was a non-spotted tan, the wild type elytra color. 

 The four traits are multiple allelomorphs. A second non-visible 

 trait in the male occurs with mosaic females (Breitenbecher, 

 1922). These females have elytra of different colors, often 

 combined with varied spotting. In a third instance the males 

 remained non-spotted tan, although the females displayed four 

 red spots on the elytra (Breitenbecher, 1923). This character 

 was dominant to the normal. Another mutation, in which the 

 male showed a complete absence of the trait, was that in which 

 all females were apterous. The males were fully winged. This 

 was a recessive character (Breitenbecher, 1925). Lastly, another 

 mutation, never visible in the male, was called "piebald." 

 Here bilateral asymmetry was manifested since the females were 

 of two types, about equal in numbers. One group had two red 

 spots on the left elytron and two black spots on the right; the 



