10 



OUR BODIES AND HOW WE LIVE 



m - 



THE PRINCIPAL TISSUES OF THE BODY 



17. The Tissues of the Body. A house, as we all know, 

 is built of timbers, bricks, stone, cement, glass, iron, and 

 other material, properly arranged and adjusted to endure 

 wear and tear, as well as for the convenience and comfort 



of its occupant. 



In a general way we may 

 say that our bodily houses are 

 built of cells of various sizes 

 and shapes, arranged in 

 groups. These sets of cells 

 compose the tissues or mate- 

 rials, and each tissue is distrib- 

 uted through different parts 

 of the body in order to do its 

 special work. 



In following chapters we 

 shall learn of two of the most 

 important of these tissues, the 



FIG. 4. Various Kinds of 

 Epithelial Cells. 



(Copter X) and the 



ciliated conical cells of the trachea; mUSCUlar (Chapter III), 



-YS2! F, the master tissues," so called 



squamous cell of the cavity of the because it is by them that 



the active life of the indi- 



mouth, seen on its broad surface; 

 G, squamous cell, seen edgeways. 



vidual is carried on. 



In the next chapter, the osseous tissue, or bone, will be 

 described. 



18. The Epithelial Tissues. One of the simplest of the 

 tissues in the body is called epithelium, and its cells are called 

 epithelial cells. It serves as a lining of various cavities, 



