GENERAL ZOOLOGY 



Esophagus ^^^^^ ^^^p 



Ovary 



"^^^t Intestine 



Optic lobe 



Brain 



Genital 

 "opening 

 Nerve \ \ Seminal 

 cord \ receptacle 



gland caeca Malpighian Oviduct 



Mouth Salivary Gastric Ventriculus 



Honnectives 



tubule 



Subesophageal Thoracic Abdominal 



J ganglion &«"elia ganglia 



, Thoracic air sac 



Abdominal air sacs 



Tracheal trunks 



Thoracic 

 spiracles 



Tracheae 

 Hemocoel 



Salivary 

 gland 



Abdominal 

 Heart spiracles 



D 



Dorsal diaphragm 



Air sac 



Nerve cord 



Spiracle 

 Tracheal trunk 



Ventral diaphragm 



Fig. 15.18. Details of some internal features of the locust. .4, lateral view, showing rela- 

 tionships of dit^estive, reproductive, nervous, and excretory systems, fi, major parts of the 

 central nervous system, ventral view. C, major parts of the tracheal system. D, cross section 

 of the body in the thoracic region; all cross-hatched structures are tracheal branches. 

 (Adapted from E. O. Essig, College Entomology, copyright 1942 by the Macmillan Company, 

 printed bv permission.) 



Structures and Functions Related to Metabolism. The internal anatomy 

 is much the same in all species of locusts. The digestive system (Fig. 15.18) 

 develops by specific modifications, extremely specialized in some insects, of an 

 originally simple tube running from mouth to anus. Only the midregion of 

 this tube, as in the crayfish, is lined by tissues derived from embryonic 

 endoderm. The anterior and posterior regions are lined by inward extensions 

 of the epidermis and are covered by cuticle, which is shed as the animal 



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