PROTOZOANS III 



appearance, contains myriads of protozoans. So abundant 

 are they that a celebrated naturalist has said that they fur- 

 nish food, directly or indirectly, for all the animals of the 

 sea. 



Many of these forms are protected by shells, which are 

 secreted by the microscopic animal. In this way they are 

 partially protected from surrounding dangers. 



The Globigerinas are forms that extract calcium carbonate 

 from the sea water and make it into calcareous shells. On 

 the inside of these shells the animal lives and through the 

 perforated surface, protoplasmic arms, called pseudopodia, 

 are extended. These animals live in countless numbers in 

 the surface water of the ocean and when they die their 

 shells fall down, forming a mass of calcareous matter at the 

 bottom of the ocean. After a very great length of time has 

 elapsed, this mass solidifies into limestone, or chalk beds. 

 This has been going on for ages and many of such beds have 

 been elevated to the surface, and form the mineral strength 

 of the most fertile soils known. 



The Radiolariae are foi^ms with shells of a siliceous nature 

 and their shells form flint beds in the ocean, which may 

 afterward become land. 



