Abstract
The variability of the race C of Drosophila auraria has been discussed with regard to intraracial sexual isolation.
Occurrence of intraracial sexual isolation between strains was detectable in many cases.
The relationship between variability in the degree of sexual isolation and that in the sixth sternite bristles of male flies was found to be parallel in some cases.
The geographical distribution of the strains is thought, however, usually to stands in a casual relationship with the degree of sexual isolation.
Certain intensification in the degree of sexual isolation with time during which the flies have been kept in the laboratory stocks was recognized.
