Glands or Organs of Secretion. 7 1 



it leaves the duct it changes instantly into the gossamer 

 thread. Bees and wasps use this saliva in forming their 

 structures. With it and mud some wasps make mortar; 

 with it and wood, others form their paper cells; w^ith it 

 and wax, the bee fashions the ribbons that are to form the 

 beautiful comb. As will be seen later, these glands are 

 very complex in bees and the function of the secretion 

 verj' varied in both composition and function. 



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. 21, j, (5), 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 stom- 

 ach are numerous urinary tubes (Fig. 21), though Cuvier, 

 and even Kirby, called these bile tubes. Siebold thinks some 

 of the mucous glands secrete bile, and others act as a pan- 

 creas. 



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

 is straight and but little, if any, longer than the abdo- 

 men, while in most plant-eaters it is long and thus zig- 

 zag in its course. It is a very interesting fact that the 

 alimentary canal in the larva, may be wholly shed at the 

 time of molting. Strange as it may seem, the fecal pel- 

 lets of some insects are beautiful in form, and of others 

 pleasant to the taste. These fecal masses under trees or bushes 

 often reveal the presence of caterpillars. I find my children 

 use them to excellent purpose in finding rare specimens. 

 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-lice, the excrement, as well as the fluid 

 that escapes from the general surface of the body, the anus, 

 or in some species from special tubes called the nectaries, 

 is very sweet, and in absence of floral nectar will often 



