426 NATURE STUDY AND LIFE 



a centimeter (.4 of an inch) in thickness, was converted into humus 

 by having passed through the alimentary canals of these two worms. 

 Darwin, loc. cit., p. 310. 



To see the earthworms at work under natural condi- 

 tions, since they are nocturnal, we must ask the pupils to 

 take a lantern in the evening and study this lesson, for 

 at least fifteen minutes, out on the ground. Just after a 

 good rain in June is the time ; for if it is dry, the worms 

 will be feeding on the materials they have drawn into 

 their holes and will not come to the surface. They may, 

 however, be induced to come out by wetting down a 

 flower bed with the garden hose. Let each child tell 

 what he has observed. 



Sometimes, especially after heavy rains, the worms are 

 seen crawling all over the ground ; but generally they 

 will be found with the tail end clinging to the burrow, 

 the body stretched out over the ground, and with the 

 mouth sucking and pulling at bits of leaves or grass. 

 When a hold is obtained on a leaf the body contracts 

 and the leaf is draw^n toward the burrow. If the children 

 have learned their lesson properly and have observed 

 this, ask them why the worm clings to its burrow. Can 

 they find eyes, nose, or ears anywhere in the body of 

 an earthworm } Can a worm see } Can it hear "^ Can 

 it smell } Let them try to answer these questions for 

 themselves by appropriate experiments and observations. 

 If they turn the light of a lantern on the head end of 

 a worm, after a few seconds it will generally draw back 

 into its burrow. This proves that it can slowly distin- 

 guish light from darkness. This is further shown by the 

 fact that earthworms are nocturnal. As to hearing, one 



