594 METABOLISM 



reasonably appetizing, but few can take the cheaper cuts of meat and con- 

 vert them into cooked dishes that are as popular and attractive. And there 

 are still fewer who can take the left-overs and trimmings and convert them 

 in the same way. This is the real art of cooking, and too much encourage- 

 ment can not be given to the effort which our cooking experts are making 

 to show people how these things can be done. The waste of good food in 

 a large city is truly appalling. 



Cooking has other advantages than making the food appetizing. The 

 heat loosens the muscle fibers of the meat so that it is more readily 

 masticated ; it destroys microorganisms and parasites in the meat ; it de- 

 stroys antibodies which might interfere with the action of the digestive 

 ferments. Thus, untreated raw Avhite of egg is not digested in the stom- 

 ach because it contains one of the antibodies which prevent the pepsin 

 from acting on it; but boiled egg Avhite, if properly chewed, can be di- 

 gested, and whipping the e<x^ white into a foam partly destroys the in- 

 hibiting substance. 



Before concluding, something should be said about the laxative quali- 

 fies of food, for it is often in this particular alone that one food is more 

 satisfactory than another. A diet of meat, milk, eggs, and white bread is 

 apt to be unphysiological because there is nothing in it to act as what has 

 been called intestinal ballast; that is, a material which will keep the 

 intestines sufficiently filled to stimulate their muscular movements. This 

 ballast is best furnished in the shape of cellulose, the most important 

 constituent of green food. Peas, beans, cabbage, salad, and many fruits, 

 especially apples, should always occupy a place in the daily menu. An- 

 other valuable food yielding this ballast is the outer grain of wheat, oats, 

 etc. So much must not be taken as to produce a constant intestinal 

 irritation, and each person must determine for himself where this limit 

 lies. The difference among various breads is almost entirely in the de- 

 gree to which they supply ballast. 



The all-important subject of food economies can receive no attention 

 here, excepl to point out that it is one which must be most carefully con- 

 sidered in the solution of all problems of dietetics. An admirable ac- 

 count of the subject will be found in Graham Lusk's "Science of Nutri- 

 tion" (third edition) and in McKillop's "Food Values." 1 



M6 



