18 The Structure and Special Physiology of Insects 
Fig. 32. Fig. 33. 
Fig. 32.—Portion of dorsal vessel and pericardial membrane of locust, Dissosteira caro « 
Una. (After Snodgrass; greatly magnified.) 
Fig. 33.—Cross-section of dorsal vessel or heart in pupa of tussock-moth, Hemerocampa 
leucostigma , showing valves. (Greatly magnified.) 
Fig. 34.—Diagram of tracheal system in body of beetle. sp. t spiracles; tr., tracheae. 
(After Kolbe.) 
Fig. 35.—Diagram showing main tracheae in respiratory system of locust, Dissosteira 
Carolina. (After Snodgrass; twice natural size.) 
Fig. 36.—Diagram showing respiratory system in thrips. st. f spiracles. (After Uzel; 
much enlarged.) 
