NORMAL HISTOLOGY. 35 



PART II. 



NORMAL HISTOLOGY. 



This brief discussion of the facts and principles of normal histol- 

 ogy is applied chiefly to animal structures, with special reference to 

 the human body. The animal body is composed of organs. Organs 

 are constituted of tissues, and tissues consist of cells and intercellu- 

 lar substances. The histologist has to do chiefly with cells. There- 

 lore, a thorough knowledge of the nature, structure, and functions 

 of the cell is necessary to an adequate comprehension of this sub- 

 ject. 



CHAPTEE IV. 



THE CELL. 



The cell is a mass of protoplasm containing a nucleus and gen- 

 erally enclosed in a thin membrane called the cell-wall. The nu 

 cleus is believed always to be present, though there are some in- 

 stances in which no nucleus has yet been discovered. The cell-wall 

 is not an essential part, and is often absent ; example, leucocytes and 

 amcebaB. 



Miller's Paraffin Bath.. 



Bausch & Lomb Optical Co., Rochester, N. Y. 



