122 STATE BOARD OF AGRICULTURE. 



ash, or mineral matter. From the fire waste products are given off — 

 smoke, soot, water and carbonic acid gas. From the body water and 

 carbonic acid gas and other waste products are given off. 



But the figure stops here. Living bodies differ from an engine in a 

 most important respect: They have the power to repair parts that are 

 injured, and to make new cells, and to grow; while when the engine is 

 injured or out of order, it must wait until some man comes to repair it. 

 It has no power to mend itself. 



FOOD IS THE FUEL OF THE BODY. 



It gives heat and energy to the body: but in addition, it repairs waste 

 tissue, and builds up new tissue. Some one may ask, how does food give 

 heat and energy? Where do heat and energy come from, and how does 

 the body make new tissue and repair itself? To answer these questions 

 thoroughly, one would need to write many books. But, first I must ask 

 the question: What is heat? Heat is described by the scientists as 

 molecular motion; that is, a motion of the smallest particles of w^hich a 

 substance is composed. When an article is cold, its molecules are said 

 to be vibrating slowly; when it is warm the- molecules vibrate more 

 rapidly. Sometimes the motion is so vigorous that the substance seems 

 to disappear from view altogether; for instance, when water becomes 

 steam. 



Heat, then, is motion — it is one of the forms of energy. But how does 

 heat get into our food? It is simply absorbed from the sun — primarily 

 in plant life; secondarily, as animal life, and stored up as latent heat, 

 it is ready to work when we want it. So when we eat, by the vital action 

 of the living cells of the body, the heat of the food is set free in our 

 bodies and we are warm and able to work. And how does the body repair 

 itself and make new tissue? This is the mystery of life — not to be solved 

 jet. 



Having come, then, to an idea as to what food is, and what it does for 

 the body, we are confronted by a number of 



PRACTICAL, CONSIDERATIONS 



such as the following: What and how much food should we eat? 

 What effect do foods have on the body? How can we get the heat and 

 waste foods for the least money? How should our foods be prepared 

 so as to give us the best results? It will be impossible to answer all of 

 these questions here — only a few of the most obvious conclusions will 

 be pointed out. 



It will be apparent, even to an untrained observer, that there is a de- 

 cided differeLce between water and corn; between salt and vinegar; 

 between bread and meat. Men have studied about foods^, and experi- 

 mented on them, and have formed a few conclusions which we may accept 

 for tlie present. We can grcup together or classify foods according to 

 their C'lPracteristics. Water will not burn, ordinarily, and salt will not 

 burn, but oil will burn. Therefore, we may divide foods into those that 

 burn, and those that do not burn — or the combustibles and incom- 

 bustibles. Water and mineral matter are substances that do not burn — 

 found in our ordinary foods. They give no heat to the body, but are 

 necessary to maintain health, and to help form tissues of the body. 



