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they develop into young worms without any 

 larval stage ; in this respect again they 

 differ from the Polychseta. The Oligo- 

 chaeta possess to a considerable degree 

 the power of regenerating lost parts, and 

 in some of the fresh-water genera asexual 

 reproduction is common, new worms being 

 formed by proliferations at the posterior 

 end of the body. Sometimes the individu- 

 als formed in this way may remain attached 

 to one another for a time, thus producing 

 temporary chains or colonies. Here, how- 

 ever, there is no alternation of generations 

 such as sometimes occurs in Polychaeta, 

 for each individual is a sexual, hermaphro- 

 ditic worm. 



Many of the fresh-water Oli^rochaeta are 

 small, even microscopic, and sometimes 

 have eyes. Those living in the earth are 

 without eyes, and sometimes become very 

 e ; the largest known is a tropical earth- 

 worm, which attains a length of two meters. 

 The common earthworm (Fig. 132) h 

 thickened band about the bod}", comprising 

 several somites about thirty segments back 

 from the anterior end. This band, the cli- 

 tellum, secretes the capsule or cocoon in 

 which the eggs are laid. The animal lives 

 in little holes in the ground, generally some 

 distance below the surface, and feeds on 

 decaying vegetable matter; this it extracts 

 from the soil, which it takes into its alimen- 

 tary canal and then deposits the undi- 

 gested portions as castings, little irregular 

 piles of soil, on the surface of the ground. 

 In this way these small animals turn over 

 e masses of earth and have accom- 

 plished almost inconceivable tasks. 1 



1 Sec Darwin. 



Vegetable Mould and Earthworms." 



