(104) 



544 C. GORDON HEWITT. 



of the stalks of the prothoracic and ventral mesothoracic imaginal discs. 

 c.l. Cerebral lobe. c.r. Problematical cellular structure (Weismann's "ring"). 

 d.a'., d.a"., d.a'". Dorsal accessory nerves, d.v. Dorsal vessel, m.c.d. 

 Major cephalic imaginal discs, ce. (Esophagus, pr.d. Prothoracic imaginal 

 disc. t. Pine tracheae which arise in association with the segmental nerves, 

 others arise with some of the more posterior nerves, but for the sake of clear- 

 ness they are not included in the figure. //., tr" . Tracheae entering the gan- 

 glion, v.m.s. Ventral mesothoracic imaginal disc. v.n. Visceral nerve. 



FIG. 25. Longitudinal section of the proventriculus of the mature larva 

 (Camera lucida drawing.) 



c.c. Large cells forming the central hollow core of the proventriculus. ch.i. 

 Glutinous intima of the oesophagus, e.v. Epithelial cells continuous with and 

 similar in character to those of the ventriculus. i.e. King of imaginal cells. 

 ce.ep. (Esophageal epithelial cells, v.c. Lumen of ventriculus. 



PIG. 26. The longitudinal lateral tracheal trunk of the left side seen latero- 

 dorsally showing the origin of the tracheal branches ; small portions only of 

 the right trunk are shown. 



a.com. Anterior tracheal commissure, a.sp. Anterior spiracular process. 

 f.b. Eat-body. or.l. Oral lobe. l.tr. Longitudinal lateral tracheal trunk. 

 p.com. Posterior commissure. p.sp. Posterior spiracle. tt j . Trachea entering 

 ganglion anteriorly, tr" . Trachea entering ganglion laterally, v.tr. Visceral 

 tracheal trunk. 



PIG. 27. Longitudinal sections through the major cephalic imaginal discs 

 of mature larva to show the position of the individual imaginal rudiments. The 

 dextral section is more dorsal than the sinistral. (Camera lucida drawings.) 



an.d. Imaginal disc of the antenna, f.d. Pacial imaginal disc. i.s. Sheath 

 of imaginal rudiments, o.d. Optic imaginal disc. o.g. Imaginal disc of the 

 optic ganglionic structures. o.s. Optic stalks, s.g. Eundament of the 

 imaginal supra-oesophageal ganglionic. sh. Sheath of cerebral lobe. 



FIG. 28. Transverse section of mature larva anterior to the ganglion and 

 cerebral lobes to show the position of certain of the imaginal discs. The body- 

 wall and muscles have been omitted. The folded character of the adipose 

 tissue laminae can be seen in this section, and also the degenerating anterior 

 portions of the malpighian tubules (m.t.). (Camera lucida drawing.) 



an.d. Antennal disc. c.r. Problematical cellular structure (Weismann's 

 "ring"), c.v. Caecum of ventriculus. d.ms. Dorsal mesothoracic (alar) 

 imaginal disc. f.c. Adipose tissue cell. l.tr. Lateral tracheal trunk, m.t. 

 Malpighian tubule cut rather longitudinally, oe. (Esophagus, pr.d. Pro- 

 thoracic imaginal disc. v.ms. Ventral mesothoracic imaginal disc. 



