94 HUMAN BIOLOGY 



holds that can afford it, is far preferable to vinegar. We 

 should always buy from neighbors when possible. Farmers 

 and gardeners should do their own drying and canning. 

 For purity of water, see Chap. X. 



The Daily Ration. - -A quarter of a pound (4 oz.) of pro- 

 teid foods and one pound (16 oz.) of fuel foods (total 20 oz. 

 of water-free foods) are needed to replace the daily waste 

 of the body. Hence a balanced ration has proteid and fuel 

 food in the ratio of 4 to 16, or i to 4. But recent experi- 

 ments at Yale University indicate that 2 oz. of proteid 

 daily are more strengthening than four. 



Appetite is a perfect guide for those wJw lead an active 

 life and eat slowly of simple food. Highly seasoned food 

 and complex mixtures deprave the appetite ; it then leads 

 astray, instead of guiding safely. Of course the appetite 

 cannot guide one to eat the right kind and quantity of 

 food at a table where the food lacks any of the four neces- 

 sary food stuffs, or where innutritious or indigestible food 

 is provided. It is well to select one food for a meal be- 

 cause it is rich in proteids, another because it is rich in fat, 

 and the third because it is rich in starch or sugar. (See 

 table, p. 95.) Intelligence in regard to diet enables a 

 housekeeper to provide nourishing food for less money 

 than an ignorant housekeeper often pays for food deficient 

 in nourishing qualities. 



A Balanced Ration. - - A deficiency of starch may be 

 supplied by an excess of fat or sugar. It is most essential 

 to provide proteid as it cannot be replaced by any other 

 food stuff. An excess of proteid is most harmful. An ex- 

 cess of starch or fat is oxidized into water and carbon 

 dioxid, which are harmless waste products ; an excess of 

 proteid is changed into urea which may become harmful 

 by overworking the liver and kidneys which excrete it. 



