280 



COMPARATIVE ZOOLOGY 



separates this organ from the intestine. The " liver," 

 really a pancreas, is highly developed ; instead of 



numerous folli- 

 cles, there is a 

 large bilaterally 

 symmetrical or- 

 gan, divided into 

 three lobes on 

 each side, pour- 

 ing its secretion 

 into the upper 

 part of the intes- 

 tine, which is the 

 true stomach. 



Among insects, 

 there is great 

 variation in the 

 form and length 

 of the canal. The 

 following parts 

 can generally be 

 distinguished : 

 gullet, crop, giz- 

 zard, stomach, 

 and large and 

 small intestines, 

 with many gland- 

 ular appendages. 

 The crop, gizzard, 



, i Qrfr _ inf^c 

 dn Idrge 



tmg are SOITl- 



timCS absent, 

 . ,, 



especially in the 

 carnivorous species. In bees, the crop is called the 

 "honey-bag.'-' The gizzard is found in insects having 



FIG. 238. Anatomy of a caterpillar : g, h, esophagus; h, 

 /.stomach; k, hepatic vessels; /, m, intestine; q, r, 

 salivary glands; /, salivary duct; a, b, c, longitudinal 

 tracheal trunks; d, e, air tubes distributed to the vis- 

 cera; f, fat mass; v, x,y, silk secretors; z, their excre- 

 tory ducts, terminating in t, the spinneret, or fusulus. 



