XIX.—“ Spheroidal”: A Mutant inDrosophila funebrisaffecting Egg Size and Shape, and Fecundity

In the course of a study of fecundity inDrosophila funebris(Donald and Lamy, 1937), it was noted that a particular female was laying very few eggs, and that the shape of these was peculiar. Among her descendants other females of similarly low fecundity and laying eggs of the same abnormal shape were encountered, and it was assumed therefore that a mutation affecting fecundity and egg shape had been recognised. In this paper evidence concerning the type of heredity of these characteristics is presented, and a statistical description of the morphological aspect of the new mutation, the size and shape of the egg, as compared with those of the normalD. funebrisegg, is given.