REDUCING APPARATUS OP INSECTS, ETC. 
187 
the alimentary canal of a Beetle, from its commencement to 
its termination. At a is seen the head, hearing the jaws, &c.; 
from this the gullet passes straight backwards, and is dilated 
into a crop at b , below 
which is the gizzard, c. This 
opens at its lower end into 
the true 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 Wheel-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 alimen- 
Fig. 112.— Digestive Apparatus of 
Beetle. 
