CHAPTER V 



WORMS AND POLYZOA 



THE average person with no special leanings towards 

 natural history has little knowledge of the animals 

 collectively spoken of as " worms," and has even 

 less inclination to increase his slender acquaintanceship. 

 The word " worm " has become synonymous with all 

 that is undesirable, and a few species, such as the earthworm, 

 the leech and certain parasitic species, embody the entire 

 group so far as the general public is concerned. 



Yet the worms are of direct biological significance, 

 and possibly no other group of animals so obtrudes itself 

 upon human destinies and that not the less potently because 

 unnoticed. Owing to the soft and yielding nature of 

 most worms few have perpetrated themselves as fossil 

 remains ; yet there is little doubt that worms were amongst 

 the earliest manifestations of animal life, since certain 

 intermediary links in the chain of evolution point to the 

 fact that the worms formed one of the starting points for 

 the higher forms of existence. 



The worms have insinuated themselves into every 

 kind of habitat. They abound in the earth, in fresh 

 water, and in the sea. They occur in all countries and all 

 climes, from the equatorial belt to high above the snow 

 line. The most primitive of these are the Flat- or Whirl- 



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