126 THE STUDY OF ANIMAL LIFE 



kinds of insect folk in carrying pollen from one 

 flower to another (even although the act is caused 

 through selfish motives), and so making possible 

 the fertilisation of various plants and trees which 

 depend upon this insect agency. 



Among the MoUusca, there are several kinds of 

 shellfish of use as food; the Earthworm has largely 

 been responsible for the production of the beautiful 

 green meadows of the England of to-day; the 

 Porifera or Sponges are distinctly useful animals, as 

 we all know ; and in our fresh and salt waters there 

 is an abundance of animal life which serves many 

 a useful purpose in the economy of Nature. 



