SCHISTOCERCA AMERICANA DRURY 157 



crop, salivary glands, coeca, ventriculus, ileum (the rest of the 

 hindgut is covered up by the reproductive organs); (2) mal- 

 pighian tubes opening into the alimentary canal, marking the 

 end of the midgut; (3) nervous system: brain above the oesoph- 

 agus in the head and ventral chain below the alimentary canal 

 with three thoracic and five abdominal ganglia; (4) heart, if 

 not destroyed by preserving process, will be seen in the mid- 

 dorsal line of abdomen above all the other organs; (5) ovarial 

 tubes, occupying all the space between the heart and the ali- 

 mentary canal in abdomen; (6) muscular system: muscles of the 

 fore and hind wings in the thorax and the muscles of the ovi- 

 positor in the abdomen; (7) endoskeleton arising from the stern- 

 ite of the thorax. 

 Additional exercises. 



(a) Take a fresh specimen and remove the dorsal body wall, 

 including wings, by an incision along each side of the body just 

 above the line of the spiracles. Examine the excised wall for 

 the heart and make a drawing of this. Fasten down the ventral 

 body wall with pins in the dissecting tray with water and care- 

 fully push the various organs apart allowing the alimentary 

 canal to lie on the left and the reproductive organs on the right. 

 This separation, if carefully performed, will expose the entire 

 alimentary canal, nervous system and reproductive organs. 

 Make a full page drawing and label parts from the text in the 

 general description. 



(b) Examine under microscope the sections through the 

 various regions of the alimentary canal and make drawings of 

 them. 



(c) Examine under microscope the section through the au- 

 ditory organ and make a drawing of it. 



(d) Examine under microscope a fresh tracheal tube (in 

 water) and make a drawing of it. 



(e) Examine under microscope the slide with the stained 

 ovarial tubes and make a drawing of it. 



