CHAPTER I 



THE SIMPLEST ANIMALS 



THE Protozoa, or simplest animals, constitute the 

 most vital portion of the sea's population. They 

 consist essentially of a single-cell and are not 

 built up of millions of cells as are the vast majority of other 

 animals. Most of these minute creatures are in varying 

 degree mobile. Some are highly so and row themselves 

 hither and thither at a great pace by means of minute 

 hairlike organs or " whips." Some are naked, others 

 are endowed with shells, and a few are of such indeter- 

 minate structure feeding in the manner of plants that 

 there is still much doubt as to whether they fall in the 

 animal or vegetable kingdom. 



The shelled species (Foraminijera and Radiolarid) show 

 a bewildering diversity in the structure of their minute 

 homes — often of exquisite design, and were until 1835 

 regarded as minute molluscs akin to the whelk and oyster. 

 It was Du Jardine who in that year startled the scientific 

 world by establishing that the animals within were of the 

 simplest construction — mere blobs of protoplasm which 

 crept along by extending hairlike filaments through minute 

 orifices in the shell's walls. Large areas of the ocean 

 bed are covered many yards deep with their deposits 

 and the dead shells of these animals may eventually become 



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