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any acid, curdles milk and draining off the solution of milk 

 sugar and salts ("whey"). It contains most of the proteid, and 

 a great deal of the fat of the milk. During the ripening of the 

 cheese more fat is formed, apparently from the proteid, while leucin 

 and tyrosin also appear. 



Meat. We use the flesh of the vegetable-feeding mammals and 

 birds that are most easily obtainable, and many kinds of fish. 

 The invertebrate animals, mostly shell-fish, need hardly be men- 

 tioned in a physiological dietary, and are not spoken of as meat. 



As it comes from the butcher, meat consists of many of the 

 animal tissues, the chief ones being flesh (muscle tissue), fat, and 

 some sinews (fibrous tissue). The fleshy or lean part of meat is 

 chiefly made up of nitrogenous materials, and contains: (1) Sev- 

 eral proteids, chiefly the globulin, myosin; (2) gelatine yielding 

 substances ; (3) carbohydrates, glycogen, and sugar ; (4) small 

 quantities of fat ; (5) several inorganic salts ; (6) extractives. 



Meat may be eaten raw, but as it is impossible to impart to it 

 the various flavors which our artificial tastes demand without some 

 special preparation, it is generally cooked before use. Moreover, 

 the not infrequent occurrence in muscle of parasites which would 

 prove injurious if swallowed alive, makes the exposure of meat 

 to a temperature high enough to insure their destruction advisable. 



Apart from pleasing the taste, it is of great importance so to 

 prepare meat as to preserve in it all the nutrient part?, many of 

 which are soluble in water, and therefore are apt to be removed if 

 that solvent be injudiciously used. Thus, the process of roasting, 

 in which all its nutrient parts are retained, ought to be more satis- 

 factory than boiling, by which the salts, extractives, carbohydrates, 

 gelatin, and some albumin may be dissolved by the water. How- 

 ever, if the meat be plunged into water which is already boiling, 

 the proteids near the surface are rapidly coagulated, and the water 

 cannot reach the central parts in sufficient quantity to remove even 

 the soluble ingredients. The whole of the albuminous parts may 

 be thus coagulated as the temperature of the inner parts rises to 

 boiling point. In treating meat to obtain "stock" ("bouillon") 

 for the foundation of soups, the opposite procedure is adopted. 

 Cold water is used, and the temperature slowly and gradually 



