8 The Under-Water World 



from a cell of crystalline mineral matter 

 in never being at rest. It must grow or 

 go under, for the reason as one eminent 

 authority has put it that " an increase 

 in size results in an increase of in- 

 dependence." Thus we find that as the 

 single-celled animals developed, the most 

 advanced cells not only increased in size 

 but began to multiply and tended to 

 dominate over their fellows. 



This restless energy led little by little 

 to the dawn of such microscopic hosts 

 as the Foraminifera lowly constituted, 

 unicellular creatures that apparently 

 realised in some mysterious way that a 

 protecting skeleton gave them an advan- 

 tage over their naked fellows. They 

 acquired shells of carbonate of lime, 

 such shells foreshadowing many types of 

 shell to be used by vastly more complex 

 animals the mollusca millions of years 

 later in the world's history. Compared 

 to the unprotected Amoebce which are 



