1 8 The Structure and Special Physiology of Insects 



FIG. 32. 



FIG. 33- 



FIG. 32. Portion of dorsal vessel and pericardial membrane of locust, Dissosteira Caro- 

 lina. (After Snodgrass; greatly magnified.) 



FIG. 33. Cross-section of dorsal vessel or heart in pupa of tussock-moth, Hemerocampa 

 leucostigma, showing valves. (Greatly magnified.) 



at. 



FIG. 34. 



FIG. 35. 



FIG. 36. 



FIG. 34. Diagram of tracheal system in body of beetle, sp., 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. si., spiracles. (After Uzel; 



much enlarged.) 



