Abstract
The pomace fly, Drosophila melanogaster Meigen, is one of the flies of the group Cyclorrhapha and suborder Schizophora which in the pupal stage possesses on the cephalic aspect of the head an extensive membranous organ or frontal sac, the ptilinum. It serves by its alternate distension and contraction to rupture the puparium and assist in the emergence of the imago. After emergence the ptilinum is permanently retracted as an invagination within the head capsule. Although the function of the ptilinum has been known since it was first described by Reaumur (1738), it is not known, to the author's knowledge, whether the failure of the adults to emerge from the puparia, in lethal flies, is dependent upon the failure of the ptilinum to function or upon some other cause. This research was instigated to determine the role of the ptilinum and attached muscles in the emergence of the normal flies. The author hopes to make a study of the lethal flies at a later time.

This publication has 0 references indexed in Scilit: