IMPORTANT FOODSTUFFS, IMPORTANT TISSUES 115 



considered in connection with the general composition of the 

 body. 



Cooking and Preparation of Foods. Some foods are pala- 

 table and digestible when raw, such as milk, fruits, nuts and 

 some vegetables. Other foods usually are prepared for use by 

 cooking. Proper cooking of food is very important, both from 

 an economic and from a physiological standpoint. Inexpensive 

 materials, if properly prepared may be quite as good and de- 

 sirable foods as more expensive materials, but even the best of 

 materals may be spoiled and rendered unfit for use by careless 

 or improper cooking. In cooking, various changes are brought 

 about in the foods. Most animal proteins are coagulated, but 

 this does not diminish, and sometimes increases their digestibil- 

 ity. The closely packed fibers of meat are loosened up so that 

 they are more easily torn apart and subjected to the action of 

 the digestive enzymes. Vegetable materials also are softened 

 and made more vulnerable to the attack of enzymes. The taste 

 and appearance of food materials also are improved in the proc- 

 ess, and this appeal to the appetite is of actual physiological 

 value in digestion. A further service performed by proper 

 cooking is the destruction of living parasites of various sorts 

 which often are found in raw foodstuffs, especially if the ma- 

 terials have been exposed in provision shops, or have been kept 

 longer than is wise. Great progress has been made in recent 

 years in regulating the care and quality of foodstuffs and thus 

 in protecting the general public from dangers arising from the 

 practices of ignorant, careless, or unscrupulous dealers. Too 

 much care and thoughtfulness can scarcely be spent in the 

 proper choice and preparation of the diet. 



Milk. Milk is one of the most important natural foodstuffs. 

 It is the natural and ideal food for the growing young, and 

 comes very near to being an ideal food even for the adult. It 

 contains all the necessary food substances, and in very nearly 

 the proper proportions. If bread or crackers are eaten with 

 it, it is an ideal food. The carbohydrate of milk, lactose, already 

 has been discussed. Cow's milk contains about 4% lactose, hu- 



