ARTICULATA. 



229 



FIG. 130. Circulation in Insects. The arrows indicate the course of the blood. 



The digestive apparatus consists of pharynx, gullet, 

 (sometimes a crop,) gizzard, stomach, and intestine. 

 The liver is represented by tubes opening into the 

 intestine. Many insects have glandular tubes, called 



a b c d e h f g 



FlG. 131. Digestive Apparatus of Beetle, a. Pharynx, b. (Esophagus, c. Crop. d. Giz- 

 zard, e. Chylific stomach, f. Small intestine, g. Rectum, k. Biliary vessels. 



from their first describer, Malpighian, which open at 

 the end of the intestine. (Fig. 131.) Some have also 



salivary glandular tubes and silk organs, Insects have 

 20 



