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MANUAL OF ZOOLOGY 



two new Amoebae possesses a nucleus similar to the original 

 one, and developed from it by division. It is mainly by 

 this simple process of division into two, or binary fission^ as 

 it is called, that reproduction or multiplication takes place 

 in the Amoeba. 



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FIG. 2. Amoeba polypodia in successive phases of division. The light spot is the 

 contractile vacuole ; the dark the nucleus. (From Lang's Text-Book, after 

 F. E. Schulze.) 



Amoeba thus consists of an undivided particle of proto- 

 plasm containing a nucleus. To such a particle the term 

 cell is applied. In higher groups the animal when fully 

 developed, consists of a number of such cells, usually differ- 

 ing in character in different parts ; and simple animals, such 



