INTRODUCTION. 5 



can rudely imitate the human voice. But this live mechan- 

 ism, which is self-winding, self-regulating, self-repairing, self- 

 directing, amazes us. 



We take up the study of the human body mainly that we 

 may learn how to preserve health ; the science of health is 

 Hygiene. 



In order to keep the various organs in good order we must 

 know what their natural work is, and how they do it ; the 

 science of the action of the body and its parts is Physiology. 

 The work, or action, of each part, or Organ, is its Function. 



In order to understand the working of each organ it is 

 usually necessary to know something of its construction ; the 

 science of structure is Anatomy. But we do not need to go 

 far into anatomy to get a fair knowledge of the manner in 

 which our organs do their work. The surgeon, of course, 

 must be able to locate accurately the various blood tubes, 

 nerves, muscles, etc. All we shall need to know of anatomy 

 is the general structure of the body and of some of the more 

 important organs, such as the heart and lungs, the larynx, 

 the eye, etc. It is fortunate for us that these organs in the 

 sheep, pig, and cow are so nearly like our own that they 

 serve admirably in enabling us to understand ourselves. 



We know that any organ is composed of several different 

 kinds of material. For instance, in a slice across a ham we 

 see the skin on the outside, then fat and lean and bone. 

 These " primary building materials" of the body we call Tis- 

 sues. These different tissues we shall study as we come to 

 them. 



The whole body is made up of small particles called Cells, 

 comparable to the bricks in a house. These cells are of vari- 

 ous shapes in the different tissues. With the blade of a very 

 dull knife, or the handle of a scalpel, gently scrape the inside 

 of the cheek. Place a little of the white scraping on a slide 



