10 PHYSIOLOGY AND HEALTH. 



this be not done, and the supply be unequal to the waste, the 

 animal loses flesh, and the body diminishes in weight. This 

 change of particles and waste of matter differ in different 

 persons, and in different circumstances, as will be shown in 

 the course of this book. 



3. Here is a double necessity for the addition of matter to 

 the body from without the growth or increase of the animal 

 body in its earlier years, and the waste consequent upon the 

 changes of the particles through the whole period of exist- 

 ence. The food supplies both these demands, and is there- 

 fore necessary from the beginning to the end of life. 



4. Food is not living flesh: much that we eat bread, 

 vegetables, fruit has not even any resemblance, in its 

 appearance or character, to flesh. Yet these matters the 

 vegetables and the lifeless meats are converted into living 

 flesh; and not only so, but into many and various kinds of 

 flesh, as many and as various as enter into the composition of 

 the human body. All this is done in part by'the digestive 

 apparatus, and in part by the blood-vessels. 



5. The digestive apparatus effects the first change in the 

 food ; it grinds it in the mouth, dissolves it and converts it in 

 the stomach into a pulpy material fit to supply the wants of 

 the blood, and sends the nutritious portions to the heart. 

 The blood-vessels carry this blood to all the portions of the 

 body, and with this they supply the growth and the waste of 

 all the organs and textures. 



0. This apparatus consists of the mouth and pharynx, the 

 (Esophagus or gullet, the stomach, and the intestinal canal. 

 In the mouth are the lips, the teeth, the tongue, and the sali- 

 vary glands. The pharynx lies back of the palate, between 

 the mouth and the gullet. The oesophagus is a tube, that 

 connects the mouth with the stomach. The stomach is a 

 large sack, in which the digestive process is mostly performed. 

 From the alimentary canal, the lacteals or absorbent vessels 

 open. These take up the nutritious portion of the digested 

 food, and carry it to the veins. Beside these organs, there 

 are some others, such as the liver and the pancreas, which 



