ELEMENTARY PHYSIOLOGY. 



CHAPTER I. 

 INTRODUCTION. 



The Care of a Machine. In order to take good care of 

 a machine one must know about its different parts, what 

 each part is to do, and the relation of the parts to one 

 another. He must keep the machine clean and well oiled, 

 and must not overwork it. Otherwise it will neither do 

 good work nor last long. This is true not only of machines 

 like typewriters and sewing-machines, but of bicycles, and 

 even of such simple tools as knives and scissors. We 

 would not trust the management of any valuable machine 

 to one who did not know enough to take good care of it. 



The Care of the Body. The care of the body is of vastly 

 greater importance. We can get new parts to replace 

 those worn out in a machine. While we can get artificial 

 limbs, we cannot replace such organs as an eye, the heart, 

 or the lungs. If we do not take good care of our bodies, 

 we cannot keep well, live long, or do good work. So we 

 need to know about the different parts of our bodies, the 

 work that each is to do, and the relation of the parts to 

 each other. 



This knowledge is desirable for everybody ; but espe- 

 cially necessary for those who live a quiet, indoor life. In- 

 door people do not get as much exercise or as much fresh 



i 



