56 Stomach and Intestines. 



tions, varies with the food. Carnivorous or flesh-eating in- 

 sects have a short alimentary canal, while in those that feed 

 on vegetable food it is much longer. 



The mouth I have already described. Following this is the 



may run as a uniform tube, as in the human body, to the true 

 stomach (Fig. 11, 6). Following this is the intestine — separ- 

 ated by some authors -into an ileum and a rectum — which ends 

 in the vent or anus. Connected with the mouth are salivary 

 glands, (Fig. 23) which are structurally like those in higher 

 animals, and in those larvae that form cocoons are the source of 

 silk. In the glands this is a viscid fluid^ but as it leaves the duct it 

 changes instantly into the gossamer thread. JBees and wasps 

 use this saliva in building their structures. With it and mud 

 some wasps make mortar; with it and wood, others their 

 paper cells; with it and wax ? the bee fashions the ribbons 

 that are to form the beautiful comb. 



Lining the entire alimentary canal are mucous glands which 

 secrete a viscid fluid that keeps the tube soft and promotes the 

 passage of food. 



The true stomach (Fig- H> &) is very muscular, and often a 

 gizzard, as in the crickets, where its interior is lined with 

 teeth. The interior of the stomach is glandular, for secreting 

 the gastric juice which is to liquify the food, that it may be 

 absorbed, or pass through the walls of the canal into the blood. 

 Attached to the lower portion of the stomach are numer- 

 ous urinary tubes (Fig. 11, c), though Cuvier, and even 

 Kirby, called these bile tubes. Siebold thinks some of the 

 mucous glands secrete bile, and others act as a pancreas. 



The intestine when short, as in larvse and most carnivora, 

 is straight and but little if any longer than the abdomen, 

 while in most plant-eaters it is long and thus zig-zag in its 

 course. Strange as it may seem, the fecal pellets of some in- 

 sects are beautiful in form, and of others pleasant to the taste. 

 In some caterpillars they are barrel-shaped, artistically fluted, 

 of brilliant hue, and if fossilized, would be greatly admired, 

 as have been the coprolites — fossil feces of higher animals-^if 

 set as gems in jewelry. As it is, they would form no mean 

 parlor ornament. In other insects, as the Aphides or plant- 



