CHAPTER IIL 



GENERAL HISTOLOGY. 



The Cell : A cell is the unit of all the living organ- 

 isms. All cells originate from a pre-existing cell. A 

 complete cell consists of the following: a cell wall, 

 protoplasm, nucleus, nucleolus and centrosome. All 

 cells are not complete : some may have a nucleus, and 

 some may not; some may have a cell wall, and some 

 may not. A complete cell is called a typical cell, and 

 one that is incomplete is called an atypical cell. The 

 cell body is a mass of protoplasm, having in it a vary- 

 ing amount of delicate fibers called "spongioplasm." 

 Along the course of these we see several little nodes. 

 These nodes are called microsomes. That part of the 

 protoplasm near the nucleus is called the nucleoplasm, 

 and that part near the cell wall is called the exoplasm. 

 The power of motion is located in the protoplasm. 

 This is illustrated in the Amoeba, a small animal which 



moves by means of pseudopods, i. e., a part of the pro- 

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