INTERNAL ANATOMY OF INSECTS. 105 



it expands into a blind sac having no connexion with 

 the stomach ; so that the fluid food, as blood, &c. stored 

 in it, must be regurgitated into the mouth before it can 

 pass into that organ a . Thus these animals, besides their 

 stomach, have a reservoir in which to store up their 

 food; the product therefore of a single meal will require 

 several days to digest it. 



2. The stomach (Ventriculus b ) is that part of the in- 

 testinal canal immediately above the bile-vessels, which 

 receives the food from the gullet for digestion, and trans- 

 mits it when digested to the lower intestines . By its 

 admixture with the gastric juice, the food acquires in 

 the stomach a quite different colour from what it had in 

 the gullet. In herbivorous insects it contains no acid, 

 but, like the gastric juice of herbivorous quadrupeds, is of 

 an alkaline nature d . The chyle is forced through this 

 organ, probably in part by the pressure of the muscular 

 fibres during the peristaltic motion ; and being pressed 

 through the inner skin, is first collected in the interme- 

 diate cellular part, and ultimately forced through the 

 outer skin e . At its posterior end it terminates in the 

 pylorus, a fleshy ring or sphincter formed of annular 

 muscular fibres f . The stomach often consists of two 

 or more successive divisions, which are separated from 

 each other, and are often of an entirely different confor- 

 mation and shape 5 . In the Orthoptera, Predaceous 

 Coleoptera, and several other insects, an organ of this 



a Ramdohr Anat. 11. b PLATE XXI. FIG. 3. d. 



c Ramdohr Ibid. 28-. 



d Hercld (Schmettcrl. 24) says that Ramdohr is mistaken here, and 

 denies the existence of this juice in insects ; but as Ramdohr's re- 

 searches were so widely extended, he is most likely to be right. 



p - Ramdohr Ibid. 29. f Ibid. 31. * Ibid. 28. 



