Human Nutrition. 749 



The body is within itself a world of little living things each having 

 its own work to perform for the good of the whole, and depending on 

 the co-operation of the whole lor its complete existence. The welfare 

 of the body is, in turn, dependent ujxjn the healthy condition and right 

 working of these little living units or groujjs of units which compose it, 

 and all is in a measure governed and determined by that which we call 

 self. The body is our kingdom; upon us rests the rcsixmsibility of its 

 right care. 



Ever}' tissue and organ in the body is made up of little living parts 

 called cells. As a part of the l)0(ly, the environment of the cell is much 

 more circumscribed than if it led an independent existence, but its 

 chances of survival are much greater through such dependence upon 

 and co-operation with other cells. We are so familiar with the body as 

 an individual thing that it is difficult to realize it as being the result of the 

 working together of countless thousands of lesser living things. The 

 cells are so small that we cannot see them individually with the naked 

 eye, but we know the tissues which represent them. Each cell has its 

 own special work to do, and though its food is brought to it and its waste 

 products removed, it must feed itself and do its own repairing. There 

 is a most wonderful division of labor among these little workers and it 

 is this specialization which has resulted in the body with its manifold 

 activities and powers. 



The muscles are communities of cells having as their part of the body's 

 work the ability to cause movement. 



Bone cells deposit around themselves quantities of mineral matter 

 and give the body a hard substantial frame work to support it. In the 

 red marrow of the bones are cells whose purpose it is to form the little 

 red corpuscles which find their way to the blood, giving it not only iis 

 red color but its power to gather oxygen from the lungs. 



Cells form the blood vessels and it is the grouping together of cells 

 which makes the skin, and all the linings of the body, the heart, tlie 

 lungs, etc. 



Certain of the cells lining the stomach and intestine and otliers grouped 

 together into bodies called glands, manufacture digestive juices which 

 are poured out upon the food and which help to get it ready for the 

 body's use. And so on and on we see this wonderful specialization pro- 

 ducing muscle and bone, skin and nerve, until the body stands forth as 

 a whole, in health all its parts working harmoniously, and all co-operating 

 to perform the body's work through the power of the cells of the nervous 

 system. Health means good condition of the cell communities; disease 



