Abstract
1. a) Plexate flies of Drosophila ananassae were sometimes accompanied with a balloon-like character. b) This character can be inherited, and the factor, though its true form has not yet been determined, seems possible to be selected. c) By the presence of heterozygous balloon, this tendency is enhanced. d) Although the expression of the unknown factor is uncertain, it is partially affected by the time of emergence, appearing more frequently in the early emerged flies. e) Sexual difference, which was recognized in the expression of the character, is reduced by half in the male.
2. a) Reversion of Plexate to normal gene was found. b) Owing to suspicion with respect to its mutable disposition, investigations were repeated, but with negative results.
