REDUCING APPARATUS OF INSECTS, ETC. 



187 



the alimentary canal of a Beetle, from its commencement to 

 its termination. At a is seen the head, bearing the jaws, &c. ; 

 from this the gullet passes straight backwards, and is dilated 



into a crop at 6, below 

 which is the gizzard, c. This 

 opens at its lower end into 

 the tme digestive stomach, 

 d; which is surrounded by 

 an immense number of little 

 follicles or bags, by which 

 the secretion of the gastric 

 juice is effected ( 204). 

 Into the lower end of this, 

 the long vessels, e, open, 

 which constitute in Insects 

 ths only rudiment of a liver 

 ( 358). In many of the 

 Crustacea, the walls of the 

 stomach are beset with re- 

 gular rows of teeth, which 

 are moved by the action of 

 powerful muscles. These 

 teeth are cast or shed at the 

 same time with the shell. 

 In the W keel- Animalcules, 

 the place of the gizzard is 

 occupied by a curious pair of 

 jaws, armed with teeth by 

 the working of which, the 

 food is effectually crushed. 

 In the Bryozoa, a gizzard 

 exists between the oesopha- 

 gus and the true digestive 

 stomach ; and the stomach 

 itself is surrounded by the 

 little follicles which secrete 

 the bile, and pour it into 

 that cavity (115). 

 203. In animals which subsist exclusively on flesh, how- 

 ever, no such complicated apparatus exists. Thus in Serpents 

 (fig. 34), the stomach is but a slight dilatation of the alirnen- 



Fig. 112. DIGESTIVE APPARATUS OF 

 BEETLE. 



