Chromosome Studies on Sciara (Diptera). I. Differences between the Chromosomes of the Two Sexes

Abstract

This paper deals with the peculiar relationship between chromosomes of the 2 sexes in flies of the genus Sciara. Males possess 2 more chromosomes than females. The 3 species studied show diploid numbers of 8 [female], 10[male]. Two extra chromosomes in male are larger than others and readily distinguished. Detailed data are given indicating (1) that the 2 "extra" chromosomes of the male are real chromosomes, (2) that they are regularly present in males and absent in females, and (3) that the condition is not peculiar to any one race or species.