Relation between Corpus allatum and Ovaries in Adult Flies (Muscidæ)

Abstract

THE adult Muscids examined by me (Musca, Calliphora and Lucilia) possess an unpaired median corpus allatum which is situated dorsal to the œsphagus in the region connecting the neck with the prothorax. Just beneath the corpus allatum lies the aorta, beneath this comes a sympathetic ganglion (ganglion hypocerebrale), and below this lies the œsophagus. An examination of newly hatched unfed females of Musca domestica showed the presence of a small rather flat corpus allatum, whereas the same organ of mature females was considerably larger, which was also the case in Calliphora and Lucilia. Thus it seems reasonable to assume that the corpus allatum of adult Muscidæ has a function similar to that of the corpus allatum of the adult female Rhodnius as found by Wigglesworth¹ (cf. also experiments of Weed on Melanoplus²), that is, to control the development of the ovaries. In order to test this hypothesis I removed the corpus allatum of rather newly hatched unfed females of Calliphora and Lucilia. It proved possible to extirpate the corpus allatum solely without damaging the aorta. The mortality was low; out of seventeen Calliphora which had their corpus allatum extirpated three died. After six days at 25° C. and normal feeding (sugar, meat and water) thirteen of the fourteen survivors showed small slightly developed ovaries, whereas one had large ovaries with nearly mature eggs. Thirteen of the fifteen operated controls (none of which died) had large nearly mature ovaries, and two had somewhat smaller ovaries with conspicuous nurse cells; but these ovaries were much larger and much more developed than the ovaries of the thirteen individuals from which the corpus allatum had been excised.