6 OUR BODIES AND HOW WE LIVE 



The carbohydrates are formed of carbon, hydrogen, and 

 oxygen, the last two in the proportion to form water. Thus, 

 we have animal starch, or glycogen, stored up in the liver. 

 Sugar, as grape sugar, is also found in the body. 



The fats contain the same three elements as the carbo- 

 hydrates, but in quite different proportions. There are 

 three chief fats present in the body. 



11. Inorganic Salts. A large number of the elements 

 unite one with another to form inorganic salts. Thus, 

 sodium and chlorine unite to form common salt, which is 

 found in many of the tissues and fluids of the body. 



Again, certain compounds of lime and soda make up 

 more than half the material of the bones. 



Compounds of iron are also found in small quantities 

 in the coloring matter of the blood, in the ash of bones, in 

 muscles, and in other tissues. 



CELLS AND PROTOPLASM 



12. Cells. All living things, whether plants or animals, 

 are made up either of a single cell or of countless numbers 

 of cells. 



The human body is built up of these minute structures 

 known as cells and the things which the cells have made. 

 These cells are so small that we must use a powerful micro- 

 scope to see them at all. 



In a general way we may describe a cell as a tiny 

 mass of jelly in which floats another still smaller mass 

 of slightly different composition, called the nucleus of the 

 larger one. 



Cells are of various shapes and sizes, spherical, flat, and 

 threadlike. Thus, we .shall learn in a succeeding chapter 



