Ill 



FOODS 



27 



reasons more important. In beef and pork are some- 

 times found little parasites and germs that cause disease 

 if taken into the body. Cooking, if well done, kills all 

 injurious things of this kind. We should never eat 

 raw meats. Many foods, especially vegetables and 

 green fruits, are more easily digested when cooked. 



Raw 



Partially cooked. 



Thoroughly cooked. 



FiG. 10. Showing how cooking changes the starch cells of potato. Drawn 

 from Year-book of Department of Agriculture, 1900 (Zinns). 



Cooking causes the cell walls of vegetables to burst, and 

 so permits the starches and sugars to escape. In meats 

 the connective tissue is loosened, and so the most im- 

 portant elements become exposed to the action of the 

 juices in the stomach and intestines. 



Apply the starch test to raw and to boiled starch. Do you notice 

 any difference ? 



32. Amount of Food. The amount one should eat 

 depends upon age, health, occupation, and many other 

 things. On an average an adult who works moder- 

 ately needs each day about one fourth of a pound of 

 proteid ; a little less than one fourth of a pound of fat ; 

 a little more than three fourths of a pound of carbohy- 



