324 FOOD AND DIGESTION 



TABLE OF PERCENTAGE COMPOSITION OF POULTRY AND FISH. (LETHEBY.) 



The flesh of nearly all animals has been occasionally eaten, and we may 

 presume that except for difference of flavor, etc., the average composition 

 is nearly the same in most cases. 



Milk. Milk is the entire food of young animals, and contains all the 

 elements of a typical diet. Albuminous substances are represented in the 

 form of caseinogen, and serum or lactalbumin; fats in thecream; carbohydrates 

 in the form of lactose or milk-sugar; salts, chiefly as calcium phosphate; and 

 water. From milk we obtain a number of food preparations, such as cheese 

 rich in protein and fat, butter and cream, buttermilk rich in proteins and 

 peculiarly well adapted for invalid diet, and whey which contains all the sugar 

 salts and the albumin. 



TABLE OF COMPOSITION OF MILK, BUTTERMILK, CREAM, AND CHEESE. 

 (LETHEBY AND PAYEN.) 



Eggs. The yolk and albumin of eggs of oviparous animals bear the 

 same relation as food for the embryos that milk bears to the young of mam- 

 malia, and afford another example of the natural admixture of the various 

 alimentary principles. The proteins of eggs are ovalbumin and ovoglobulin 

 and the phosphoprotein, the vitellin of the yolk. In addition to the three 

 common fats there is a yellow fatty pigment, lutein (lipochrome), lecithin, and 

 cholesterol, a small quantity of dextrose, and inorganic salts, chiefly calcium, 

 potassium, sodium chlorides, and phosphates. 



