110 PHYSIOLOGY AND HEALTH. 



CHAPTER IV. 



Object of Eating and Circulation is to nourish the Body. AJ1 Ani- 

 mal Solids and Fluids formed out of the Blood. Elementary 

 Composition of the Blood and Flesh : nearly alike in all the Tis- 

 sues, but differ in the Proportions of their Elements. Nutrition 

 takes Place in the extreme Vessels, and with unerring Precision. 

 Growth and Changes of the Body are at the Cost of the Blood. 

 The Atoms of the Body enjoy but a temporary Life. When one 

 dies, it is removed. Absorbents. 



238. As the eating and digestion of the food have .no 

 other object than to supply the wants of the blood, so the 

 motions of the heart, and the circulation of the blood, are 

 for the sole purpose of supplying the wants of the frame. 

 All the growth of the body in childhood and youth, all the 

 regaining of flesh after sickness, all increase of flesh at any 

 period of life, and all the changes of particles, are supplied 

 by the blood. All the tissues and secretions of the body, 

 various as they are, the bone, muscle, brain, skin, fat, 

 the hair and the nails, the tears, the' saliva, and the perspira- 

 tion, - are all taken from this same-storehouse, from this 

 fluid that runs in the blood-vessels of the animal body. 



239. The blood is not flesh^nor does it exhibit any resem- 

 blance to flesh. It is a homogeneous fluid, the same in all 

 the arteries, wherever they may be situated. The blood that 

 flows -in the brain is of the same^nature and composition as 

 that which flows in the bones and muscles. The blood is 

 not a simple, but a compound fluid. It contains various ele- 

 ments, and these are the same as those which compose the 

 flesh. These simple elements are principally carbon, oxygen, 

 hydrogen, and nitrogen. There are. others, such as the lime, 

 that enters the bones, some phosphorus and sulphur, that are 

 found in the hair, the nails, and the brain. These are the 

 most common elements in nature. Oxygen and. nitrogen 

 compose the air ; oxygen and hydrogen form water. Carbon 



