118 EN TOMOLOGY 
The crop is conspicuous in most Orthoptera (Fig. 145) and 
Coleoptera (Fig. 146) as a simple dilatation. In Neuroptera 
(Fig. 147) its capacity is increased by 
Fic. 147. means of a lateral pocket—the food reser- 
vor; this in Lepidoptera, Hymenoptera 
and Diptera 1s a sac ( Fig. 148, ¢) commu- 
nicating with the cesophagus by means of 
a short neck or a long tube, and serving as 
a temporary receptacle for food. In her- 
bivorous insects the crop contains glucose 
formed from starch by the action of saliva 
or the secretion of the crop itself; in car- 
nivorous insects this secretion converts 
albuminoids into assimilable peptone-like 
substances. 
Next comes the enlargement known as 
the proventriculus, or gizzard, which is 
present in many insects, especially Orthop- 
tera and Coleoptera (Fig. 146), and 1s 
usually found in such mandibulate insects 
as feed upon hard substances. ‘The pro- 
Digestive system of Vemtriculus is lined with chitinous teeth or 
Uyricem lavas) 6 ridees Tor stramine the food, and: as 
cecum; cr, crop; m, mid . ; 
intestine; mt, Malpighian poOwertul circular muscles to squeeze the 
tubes; s, | spinneret.— 
After MEINERT. 
food back into the stomach, as well as 
longitudinal muscles for relaxing, or open- 
ing, the gizzard. Some authors maintain that the proventricu- 
lus not only serves as a strainer, but also helps to communute 
the food, like the gizzard of a bird. 
In most insects a cardiac valve guards the entrance to the 
stomach, preventing the return of food to the gullet. This 
valve (Figs. 144, 149) is an intrusion of the stomodzeum into 
the mesenteron, forming a circular lip which permits food to 
pass backward, but closes upon pressure from behind. 
Mesenteron.—The ventriculus, otherwise known as the 
