Morphological Differences between the "Races" of Drosophila Pseudoobscura

The use of suitable statistical analyses permits the demonstration of racial differences in the numbers of the sex-comb teeth and in certain measurements of the legs and wings, when taken on male flies. No such differences were found between females of the two races. The differences in numbers of sex-comb teeth were constant over a series of experiments even when performed at different temperatures. The use of these criteria for assignation of strains to the two races would result in 10 per cent. misclassification.