INSECTS AND OTHER SMALL ANIMALS 



2 93 



special study of the earthworm, making prominent 

 its great importance and benefit to agriculture. He 

 estimated that in some parts of Eng- 

 land this little animal, in boring, brings 

 to the surface ten tons of subsoil to the 

 acre. It bores its hole in the ground 

 by passing the earth through its body. 

 This hole may be six to eight feet in 

 depth. 



The angleworm feeds on organic 

 matter in the earth, and sometimes 

 draws into its hole small bits of leaves 

 which it uses as food. During the 

 day it remains in its hole unless forced 

 out by the filling of its hole with 

 water, as during a heavy rainstorm, 

 but at night it comes to the surface 

 to feed. During the winter it hiber- 

 nates below the frost line. 



It is difficult to estimate the value 

 to agriculture performed by these lit- 

 tle creatures. The large amount of a> the worm itself; j, a 

 subsoil worked over by them and de- 

 posited at the entrances to their holes 

 in little pellets of earth, called cast- 

 ings, is one means of constantly re- 

 newing the soil. The holes also admit 

 air and water, both beneficial to the subsoil ; and the 

 vegetable matter drawn into their holes increases the 

 humus in the soil. 



Note. Tapeworms, which infest the intestines of animals, and 

 trichinae, small worms found in the lean part of pork, are parasitic 

 worms not belonging to the same division as the Annulata, 



FIG. 148. Earth- 

 worm. 



small part magnified to 

 show bristles pointing 

 backward. These aid 

 the worm in moving for- 

 ward, c, egg of worm; 

 d, young worm coming 

 out of the egg. (Bur- 

 nett.) 



