1 5 2 EARTH- WORM. PART in. 



With a low magnifying-power they appear to be minute 

 points regularly pushed out and drawn in; but when 

 more highly magnified each point is seen to consist of 

 two transparent glassy rods having their points bent 

 backwards : on these feet the worm crawls very rapidly. 

 While making its cylindrical burrow a slimy mucus 

 exudes from the body of the worm, which cements the 

 particles of earth together and renders the walls of the 

 burrow perfectly smooth and slippery. When the worm 

 pierces the earth it stretches its snout into a fine point 

 that it may penetrate more easily, and when it is fixed, 

 it draws its ringed body towards its head by a muscular 

 effort; and to prevent it from slipping back again, it fixes 

 the hooks of its posterior feet firmly into the ground. 

 Having thus secured a point of support it penetrates 

 deeper into the earth, draws up its body, fixes the hooks 

 of the posterior feet into the smooth surface of the bur- 

 row, and continues the same process till the burrow is 

 deep enough. Thus the feet are employed as points of 

 resistance for the exertion of muscular force. This 

 worm swallows earth mixed with decaying animal and 

 vegetable matter, assimilates the nutritive part, and 

 casts out the refuse in the form of fine mould, which 

 may be seen in little heaps at the 

 edges of their burrows. In fact, 

 nearly all the fine vegetable mould 

 so precious to gardeners and farmers 

 has passed through the intestines of 

 the common earth-worm. 



There is a colourless little fresh- 

 water species of the genus Nais, re- 

 markable for the beauty of its bristled 

 feet. There are two pairs on each 



Fig. 132. FootofNai's. . r 



ring ot the worm, consisting 01 wart- 

 like perforated protuberances, through which a number 

 of microscopic bristles protrude, arranged in a radiating 



