PHYSIOLOGY AND HEALTH. 



PART I. 



DIGESTION AND FOOD. 



CHAPTER I. 



Growth of the animal Body, and the Changes of its Particles supplied 

 by Food. Food converted into Flesh by the Digestive Apparatus 

 and the Blood- Vessels. Digestive Apparatus. Mouth. Teeth. 



1. THE animal body increases in size and weight from 

 birth to manhood. The chief material which supplies this 

 growth is the food we eat. Beside this, there is another de- 

 mand for food. During the whole of life, there is an inces- 

 sant change going on in the particles that compose the body. 

 It is a law established by the Creator from the beginning, 

 that life cannot continue long in animal matter. The atoms, 

 which compose the living body, receive the principle of life 

 when they enter their appointed places, and become apart of 

 the animal frame. They retain this principle but a short 

 period, and, while they retain it, they perform their part of the 

 work of life. But soon their work is finished, and then they 

 yield their vitality, and give up their places to other atoms, 

 that come to enjoy life, and work a while, and yield and de- 

 part, as those that went before them had done. 



2. This law of unceasing change is impressed upon all 

 animal beings. In all, the particles are constantly going out 

 through the skin and the lungs, and an equal quantity of 

 matter must, therefore, be coming' in through the mouth. If 



