CHAPTER III 

 THE BODY ORGANIZATION 



WHAT is the nature of the body organization ? What are 

 the individual parts, or units, that make it up ? What 

 general work do these carry on and upon what basis do 

 they practice the division of labor ? The answers to these 

 questions will suggest the main problems in the study of 

 the body. 



Complex Nature of the Tissues. To the unaided eye 

 the tissues have the appearance of simple structures. The 

 microscope, however, shows just the 

 reverse to be true. When any one of 

 the tissues is suitably prepared and 

 carefully examined with this instru- 

 ment, at least two classes of materials 

 can be made out. One of these con- 

 sists of minute particles, called cells ; 

 the other is a substance lying between 

 the cells, known as the intercellular 

 material (Fig. 3). The cells and the 

 intercellular material, though varying in their relative pro- 

 portions, are present in all the tissues. 



The Body a Cell Group. The biologist has found that 

 the bodies of all living things, plants as well as animals, 

 consist either of single cells or of groups of cells. The 

 single cells live independently of one another, but the cells 

 that form groups are attached to, and are more or less 

 dependent upon, one another. In the first condition are 



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FIG. 3. Diagram 

 showing the relation of 

 the cells and the inter- 

 cellular material. C. 

 Cells. /. Intercellular 

 material. 



