IN November 1925, while examining a series of sections through the larva of the rice weevil (Calandra oryzae, Linn.), I was puzzled by the presence of a comparatively large mass of cells between the nervous system and the alimentary canal in the region where the fore-gut passes into the mid-gut. Later on, by examining sections through metamorphosing larvae, it was noticed that this mass takes part in the formation of the adult mid-gut. This suggested that a detailed study of the origin and behaviour of this mass, together with a study of the development of the larval mid-gut and that of the adult, might be of some interest to the embryologist and probably to the systematist also.
The development of the mid-gut epithelium of insects has for the last fifty years been the subject of numerous investigations, not only from the point of view of comparative insect embryology, but also...
