I 12 HUMAN BIOLOGY 



Milk of cows is improperly called a perfect food by some writers. 

 Although it contains the four classes of food stuffs, the proteid is in ex- 

 cess, the fuel food being deficient. Buttermilk is more digestible than 

 sweet milk. Buttermilk and sugar form a valuable food for infants. 

 Skimmed milk still contains the proteid, the most nutritious part of 

 the milk. Sour milk, or "clabber," and curds pressed into "cottage 

 cheese "are more digestible than sweet milk. Cream is more easily 

 digested than butter, which is a solid fat. Cheese is a very concentrated 

 proteid food, and should be eaten sparingly. Eggs are a valuable food. 

 Is there more proteid or fat in eggs? (See Table.) Pork and veal 

 are the most indigestible of meats. FisJi is nearly as nutritious as meat. 

 There used to be a supposition that fish nourished the brain because 

 it contains phosphates ; but there are more phosphates in meat than 

 in fish, and more in grains than in meat. 



Grains contain considerable proteid (gluten), but they especially 

 abound in starch. Wheat flour contains more gluten than corn meal, 

 hence it is more sticky, and retains the bubbles of gas so that the 

 dough rises well in bread making. Eggs are sometimes added to 

 corn meal to make it sticky and cause it to rise well. Which grain has 

 the largest percentage of oil? (See Table.) Of starch ? Of gluten? 

 Which is poorest in gluten? Grains may be made to resemble fruit 

 by long cooking at a high temperature (300 Fahr.), for their starch is 

 thus changed to dextrin, a substance resembling sugar. You learned 

 that the starch of fruit is turned into sugar as the sun ripens it. Dex- 

 trin is yellow and gives the dark color to toasted bread. It is changed 

 to sugar almost instantly when brought in contact with saliva. It is 

 used as a paste on postage stamps. 



Vegetables contain much water and woody fiber. White potatoes we 

 underground stems and are one fifth starch. Yams, or sweet potatoes, 

 resemble roots, and contain both starch and sugar. Beans and peas 

 are very nutritious. They have been called " the lean meat of the 

 vegetable kingdom. 1 ' They require boiling for several hours. If the 

 skins are removed by pressing them through a colander, they are very 

 easy of digestion. This puree of beans makes delicious soup. "Hull- 

 less beans" and " split peas" are also sold by grocers. 



Practical Questions. — 1. Clothing and shelter for man or 

 beast economize what kind of food? 2. Why should bread remain 

 longer in the mouth than meat? 3. In snowballing, what is the ap- 

 pearance of the hands when they itch from cold? Extreme cold irri- 

 tates and congests the stomach more quickly than it does the hands. 

 Why is it that ice water does not satisfy the thirst, but often produces 

 a craving to drink more water? 4. Should biscuits having a yellow 



