THE EARTHWORM 105 
kingdom which include these forms, in that its body, which 
is soft, is without a backbone. 
General Description. In shape the worm is long and 
roughly cylindrical, though slightly flattened on the under 
surface. Itsbody is made up of a large number of 
segments or rings which can be easily made to contract or 
' 
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Fig. 69.—A, Head of Earthworm. B, Section of Body showing Segments 
carrying Bristles. C, Burrowing Worm and Castings. 
expand. One end of the body is more pointed than the 
other—it is here that the head is situated, with the mouth 
in the first segment, The skin is kept moist and slimy 
by numerous glands which pour out mucus, and so prevent 
too rapid evaporation of moisture. It is of the utmost 
importance that the skin remains moist. Harthworms 
have neither lungs nor gills but obtain a supply of air 
