.\\.\To\n \\D PHYSIOLOGY 



103 



tube. MIL I serving u M temp ceptacle for food. In herbiv- 



orous Insects tin- Crop COntailU glUCOM formed in,m ^tanh by the 

 action of saliva or by tin- Secretion of tin- (Top iNelf; in carnivorous 



ts tin's secretion convc-rts all)inninoi(ls into assimilable pep' 

 like subslaih 



Next conies the' enlargement known as the prmmlriculus, or 



ird, which is present in many 

 insects, especially ( )rthopteraand 

 Coleoptera (Fig. 148), and is 

 usually found in such mandibulate 

 insects as feed upon hard sub- 

 stances. The proventriculus is 



mt 



FIG. 148. Digestive system of a beetle, 

 Carabus. a, anal gland; c (of fore gut), crop; 

 c (of hind gut), colon, merging into rectum; 

 d, evacuating duct of anal gland; g, gastric 

 caeca; i, ileum; m, mid intestine; mt, Mal- 

 pighian tubes; o, oesophagus; p, proventricu- 

 reservoir. After KOLBE. 



FIG. 149. Digestive system of Myrme- 

 leon larva, c, caecum; cr, crop; m, mid 

 intestine; mt, Malpighian tubes; s, spin- 

 neret. After MEINERT. 



lined with chitinous teeth or ridges for straining the food, and has power- 

 ful circular muscles to squeeze the food back into the stomach, as well as 

 longitudinal muscles for relaxing, or opening, the gizzard. The pro- 

 ventriculus not only serves as a strainer, but also helps to comminute 

 the food, like the gizzard of a bird. 



