Annulata. 97 



The Senses of the Earthworm. The sense of touch is 

 undoubtedly most fully developed, and on this sense the 

 worm largely depends for its knowledge of the outer 

 world. 



The sense of taste exists, and probably smell also, for 

 the earthworm exercises choice of various foods offered it, 

 as shown in many experiments made by Darwin. 



The earthworm can distinguish between light and dark- 

 ness, as evidenced by the fact that it retires to its burrow 

 at the approach of day. When a strong light is flashed 

 upon the anterior end of the earthworm, it retreats. The 

 posterior end is also sensitive to light. But there is no 

 reason for supposing that the worm sees objects with any 

 distinctness, as do animals with well-developed eyes. There 

 is no evidence of a sense of hearing. 



Development of the Earthworm. The ovaries are small 

 and close to the ventral surface, usually in the thirteenth 

 segment. The oviducts open on the fourteenth segment. 

 The eggs are inclosed in capsules of albuminous material 

 formed by the girdle, or clitellum. In May and June the 

 capsules containing the eggs of one species are deposited 

 in the earth under logs and stones, or especially in, or 

 under, manure heaps. The little worms are about an inch 

 long when hatched. 



Enemies of the Earthworm. The principal enemies of the earth- 

 worm are moles and birds. To escape the latter the worms usually 

 retire into their holes at the approach of day, often plugging the mouth 

 of the hole with pebbles. If they are too slow in hiding, or neglect to 

 shut the door, the sharp eyes of the bird may discover them. The 

 early bird gets the late worm. 



Distribution of Earthworms. Earthworms are very widely dis- 

 tributed, being found nearly all over the world, even in isolated islands 

 of the ocean. There are many species, but they are all much alike in 

 most features which are essential for our present knowledge. 



