350 AGRICULTURE ON THE PACIFIC SLOPE 



(protein). In figure 181 the muscle-making food is 

 shown in black in each square; the heat-making food 

 is shown in white. You see that milk contains both 

 kinds of food. B^ef, eggs, and beans contain a great 

 deal of muscle-making food, as you may see from the 

 large black part of the squares in the figure. 



In order to keep well and strong we must eat a good 

 many different kinds of food, such as meat, fish, vege- 

 tables, fruit, and sweets, and especially of the kinds 

 we enjoy most. Then we should drink plenty of pure 

 water and take plenty of exercise in the fresh air to 

 make our food digest. 



How to cook food. Cooking not only makes food 

 taste better, but helps to digest it. A lump of dough is 

 partly digested while it is being baked into bread. Part 

 of it is changed to sugar, and this makes the crust taste 

 sweet. In the body the same thing happens. The 

 starch is partly changed to sugar in digestion. The 

 brown sticky substance of the crust is also made from 

 the starch by partly digesting it. 



We make dough by mixing flour with water and add- 

 ing sugar, salt, and sometimes butter or milk. We 

 also add yeast or baking powder, and let the dough 

 stand in a warm place. Bubbles of gas (carbon dioxide) 

 begin to rise and lift up the dough into a light spongy 

 mass. If the dough contains enough protein, it will be 

 tough and hold the gas bubbles even when they grow 

 larger in the heat of the oven. But if there is too 



