ANATOMY AND PHYSIOLOGY I1g 
mud intestine, or stomach, is usually a simple tube of large 
caliber, as compared with the cesophagus or intestine, and into 
Fic. 148. 
: mt 
ii cL Os 
Ws 
* 
' Ly Be, Bh ; 
ese F yy Xx | = Stn 
Alimentary tract of a moth, Sphinx. c, food reservoir; cl, colon; cm, cecum; i, ileum; 
m, mid intestine; mt, Malpighian tubes; 0, cwsophagus; r, rectum; s, salivary gland.— 
After WAGNER. 
the ventriculus may open glandular blind tubes, or gastric 
c@ca (Pigs. 145, 146); these, though 
numerous in some insects, are commonly 
few in number and restricted to the ante- 
rior region of the stomach. The gastric 
ceca of Orthoptera secrete a weak acid 
which emulsifies fats, or one which passes 
forward into the crop, there to act upon 
albuminoid substances. In the stomach 
the food may be acted upon by a fluid 
secreted by specialized cells of the epithe- 
lial wall. In various insects, certain cells 
project periodically into the lumen of the 
stomach as papillze, which by a process of 
constriction become separated from the 
parent cells and mix bodily with the food. 
A } : Cardiac valve of young 
this phenomenon, takes place in the larva. 4). ais. ogee 
of Piychoptera (van Gehuchten), also in 2848: # proventriculus; 
S ae ; 5 : v, valve. In an older 
nymphs of Odonata (Needham), and is larva the valve projects 
into the mid intestine.— 
probably of widespread occurrence among Aree Kowateveny, 
insects. The chief function of the 
