PHYSIOLOGY OF INSECTS. 143 



CHAPTER VIII. 



OF THE ALIMENTARY CANAL, OR ORGANS OF 

 DIGESTION. 



539. THE alimentary canal in insects, as in 

 higher animals, consists of three principal parts, 

 the gullet, the stomach, and the intestines. 



540. The gullet (oesophagus) is the part which 

 most nearly approaches the head, and the external 

 opening of which is the throat (pharynx) already 

 described ; it is of various length ; and in this par- 

 ticular it appears more influenced by the variation 

 of external form than by the quantity or quality of 

 food consumed. 



541. The gullet is simple (oesophagus simplex) 

 when it is merely a tube of uniform size extend- 

 ing from the pharynx to the entrance of the 

 stomach : this is the usual structure. 



542. The gullet is ventricose (oesophagus ven- 

 tricosus) when it dilates into a large bag or crop 

 before its union with the stomach, and detains the 

 food in its passage to that organ. 



543. The gullet is compound (oesophagus 



