i8 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 



leiicosligma, showing valves. (Greatly magnified.) 



Fig. 34. Fig. 33. Fig. 36. 



Fig. 34. — Diagram of tracheal system in body of beetle, sp., spiracles; Ir., trachesc. 



(.After Kolbc.) 

 Fig. 35. — Diagram showing main trachea: in respiratory system of locust, Dissosteira 



Carolina. (.After Snodgrass; twice natural sire.) 

 Fig. 36. — Diagram showing respirator)' system in thrips. St., spiracles. (After Uzel; 



much enlarged.) 



