CHAPTER VI 



THE EARTHWORM I NEREIS CHARACTERS OF THE PHYLUM 



ANNULATA 



THE general form and appearance of an earthworm 

 are familiar to everyone. In this country there are a 

 number of different species of earthworms belonging to 

 several genera, the commonest of which are Lumbricus 

 and Allolobophora ; but the differences between these 

 are of minor importance to the beginner, and any one of 

 the common forms will serve our purpose. 



Earthworms burrow into the soil and live on decaying 

 leaves and other organic matter, which they swallow to- 

 gether with a considerable quantity of earth. This earth, 

 mingled with the undigested portions of the food, 

 is passed from the body on to the surface of the ground 

 in the form of the well-known little heaps or " castings " 

 which you must have noticed in gardens and fields, 

 especially after rain, when the worms come more 

 frequently to the surface. In this way a quantity of 

 finely divided earth, mixed with the faeces of the worms, 

 is constantly being spread out on the surface of the soil, 

 and Darwin calculated that on an average a layer of 

 earth about one-fifth inch in thickness, or about ten tons 

 an acre, is thus brought to the surface in the course of 

 a year. Earthworms are therefore good friends to the 



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