THE RINGED WORMS OR ANNELIDS I-ig 



laid in a cocoon secreted by the clitellum. When the 

 cocoon is formed it is slipped forward over the head, re- 

 ceiving the eggs as it passes the mouths of the oviducts, 

 and deposited usually in a damp place. 



Earthworms retreat from places that are very warm or 

 dry; they are much more apt to come to the surface in 

 damp or rainy weather when they may leave their bur- 

 rows. At such times we may find th,em strewn about 

 upon sidewalks and various other places much to the de- 

 light of robins and many other birds that prey upon them. 

 Earthworms may be found even on the roofs of houses 

 where many people suppose that they must have rained 

 down. As a matter of fact they crawl up the sides of 

 the house, as you may readily see them do if you give them 

 the chance. 



Earthworms have remarkable powers of regeneration. 

 If a considerable part of either end is removed the worm 

 will after a time regenerate the missing segments. Some 

 of the aquatic relatives of the earthworm regularly mul- 

 tiply by fission in addition to developing from fertilized 

 eggs. 



As Darwin has shown in his interesting book on "The 

 Formation of Vegetable Mould through the Action of 

 Worms," earthworms play a very important part in the 

 production of fertile soil. They burrow to a depth of 

 several feet and bring to the surface a large amount 

 of material that has passed through their bodies in their 

 "castings" which accumulate around the mouths of their 

 holes. These castings may be seen in any region in which 

 the earthworms have recently been burrowing. They 

 are washed away by rains or blown by winds; and, as Dar- 

 win has estimated, their removal may produce consider- 

 able change in the surface of the soil. As a consequence 

 of bringing up soil from below the surface, rocks and other 



