104 THE USES OF FOODS 



in passing foods through the food tube and in expelling 

 wastes from it. 



The influence of the mind on digestion. Not many 

 years ago, it was discovered in experiments with the X-ray 

 machine that the peristaltic movements of the food tube 

 were stopped or arrested when a cat or a dog was frightened 

 or angry, but when contented and happy the movements 

 began again and continued normally. These experiments 

 teach us a very real lesson, for our own food tube acts in 

 the same manner. Form the habit of contentment. At 

 meal times especially learn to be cheerful and happy. 

 Laugh and grow fat is a statement founded on simple 

 scientific fact. 



Some reasons for differences in diets. It goes with- 

 out saying that you would not fill up the fire box of 

 your furnace with as much coal on a day that promised to 

 be warm as on a cold day. Similarly we do not always 

 need the same amount and kind of food. A man doing hard 

 work, for example, would need very much more energy- 

 giving food than a man doing little work. 



We find that environment plays a very important part in 

 diet. People living in hot climates need different foods from 

 those in cold climates. The inhabitants of cold countries 

 need more heat-releasing foods, and use fats for this pur- 

 pose. In summer we do not require so much fat as we do 

 in winter, and watery foods, such as fruits, vegetables, 

 milk, eggs, and cereals, are better than much meat and 

 fats. Age should cause a difference in the kind of food. 

 We take food in order to make new body material, to repair 

 what is wasted, and to give us energy. Very young chil- 

 dren grow rapidly, and should use milk largely in their diet. 

 A study of the diagram will show you the reason for this. 



