The Effect of the Lozenge Pseudoallelic Series on Eye Pigmentation in Drosophila Melanogaster. II. Red Pigment and Pigmentation in Lozenge Compounds.

N the investigation of pigmentation among the lozenge series of pseudoalleles I in Drosophila melanogaster, the amount and distribution of red and brown pigments in the compound eyes of the lozenge mutants can be analyzed histologically by studying the genic effect on the two pigments separately. In an earlier report (CLAYTON 1957), the distribution of pigment in males of the lozenge mutants was described. as well as the distribution of brown pigment in lozenge males homozygous for the mutant brown. In continuing this study, an analysis has been made of lozenge females homozygous for vermilion ( U ) or scarlet ( s t ) and eighteen compounds of females heterozygous for two different lozenge alleles but homozygous for scarlet. OLIVER (1947) described the eye colors in ten of the lozenge alleles and the appearance of the eyes with scarlet and vermilion. GREEN ( 1948) analyzed quantitatively the amount of red pigment present in the eyes of seven types of lozenge females which were homozygous for a logenge mutant and for vermilion. A number of investigations have been made on the lozenge effect in compounds; these studies are discussed in an earlier paper on the structural abnormalities of the ommatidia in lozenge compounds (CLAYTON 1954a). GREEN and GREEN (1949) observed that the phenotypic effects of the lozenge mutants, when classified on the basis of the quantity of red pigment present in the eyes, were distributed at random at the three loci assigned to these pseudoalleles. In the analysis of the ommatidial abnormalities in the compounds, no correlation between the loci involved and the severity of structural defects could be found. In the present investigation, an analysis has been made to determine, by histological methods, the distribution of red pigment in ten of the lozenge mutants and in the compounds of these mutants in order to correlate the appearance of the eyes with abnormalities in eye structure and pigment distribution.