CHAPTER XIX 



THE INTERNAL ANATOMY OF THE LOCUST 



SECTION XII 



Material. Fresh material will be found the most satisfactory for this work, 

 the specimens being placed in 85 per cent alcohol for about an hour before 

 being used. If fresh material is not available, alcoholic specimens that have been 

 previously soaked in warm water for a short time will work very satisfactorily. 

 After removing the wings and legs from the right side of the locust, make a 

 longitudinal, dorsal incision to the right of the median, dorsal line, and the 

 entire length of the body. Make a similar longitudinal ventral incision to the 

 right of the midventral line. Remove carefully the right side of the chitinous 

 covering, exposing all of the internal organs, of which the following systems 

 should be studied : 



1. Digestive system. The digestive system occupies the greater 

 part of the thoracic and the ventral part of the abdominal cavity. 

 It is essentially a continuous tube, divided into the following re- 

 gions, each with a particular function to perform. 



a. The esophagus. This is a cylindrical tube, with tough, mus- 

 cular walls. It runs from the mouth, opening dorsally to a point 

 opposite the foramenal aperture, where it bends at right angles 

 and enters the thorax. 



b. The crop. This is an enlargement of the esophagus and, be- 

 ginning in the mesothorax, runs to the abdomen, almost filling the 

 mesothoracic and metathoracic cavities. 



c. TJie gizzard (proventriculus). This is the next division (not 

 found in the genus Acridium). The walls are thick and muscular, 

 and on the inside are lined with a series of chitinous plates which 

 are used in completing the mastication of the food. 



d. The stomach (ventriculus). This division is separated from 

 the gizzard by a slight constriction. It is approximately the same 

 diameter as the gizzard and extends from the first to the seventh 

 segment of the abdomen. 



e. The large intestine. This is of somewhat smaller diameter 

 than the stomach and runs from the seventh to the tenth segment. 



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