170 ZOOLOGT 



fly, and are in consequence weak or dying. During the day- 

 time, if tlie surface moisture permits, they lie near the mouth 

 of their burrows, probably for the sake of the sun's warmth. 

 In this position the}' can be seen by looldng down into the 

 holes. At such times thej' are often caught l)y hinh. In dry 

 weather, or when the ground is freezing, earthworms burrow 

 deep to a moist stratum, or to below the frost-line, and hiber- 

 nate there. 



Food. — Earthworms are omnivorous. As thej' l)urrow 

 through the ground, the earth is taken into the food tract, and 

 the digestible particles are dissolved out and absorbed as food. 

 Earthworms can, however, be fed upon green and dead leaves, 

 decaying wood, seedhngs, bits of fle,sh, and even filter paper. 

 Earthworms have the habit of dragging into their burrows 

 leaves which they intend to devour. There the leaves are 

 moistened with a fluid excreted b}' the worm. This fluid 

 partially digests the food. After l^eing taken into the alimen- 

 tary tract, the food reaches an organ of the canal known as the 

 gizzard. This part has thick muscular walls, and contains 

 in its cavity small stones ; by the action of Iwth the muscular 

 gizzard and the small stones, the food is ground up in much the 

 same way as are the grains of corn by the aid of stones in the 

 gizzard of a hen. 



Resistance and Regeneration. — Earthworms have a re- 

 markafile power of resisting certain imtoward conditions. 

 Tlius they may be kept for months in a moist vessel without 

 food, or with only filter paper, with.out starving. On the other 

 hand, they die in a dry atmosjihere in a few hours, whereas 

 they may be submerged in water for several days ^Yithout 

 injury. Very remarkalile is their power of healing after injury. 

 If an earthworm be cut in two near the middle, and the halves 



