By roughly arranging foods according to such a table we can arrive approximately at a suitable balance of its various constituents. But the chemical side of the PERCENTAGE OF TOTAL HEAT VALUE OF FOOD FURNISHED BY ITS PROTEIN FAT CARBOHYDRATE Per cent. Per cent. Per cent. Lean beef (boiled) 90 Butter 99 Tapioca (cooked) 98 Chicken 79 Bacon 94 Prunes (dried) 97 Mackerel 50 Cream 87 Figs (dried) 95 Skim Milk 37 Brazil Nuts 86 Rice (boiled) 89 Eggs 32 Fat Ham 81 Oysters 89 Beef with fat 25 Fat Beef 75 Potatoes (boiled) 88 Cheese 25 Cheese 73 Bread 81 Fat Ham 19 Eggs 68 Peas 72 Milk 19 Boiled Mutton 65 Milk 29 Bread 13 Milk 52 Cream 8 Potatoes 11 Mackerel 50 Brazil Nuts 4 Boiled Rice 10 Chicken 21 Cheese 2 Brazil Nuts 10 Boiled lean Beef 10 Bacon 6 Bread 6 Cream 5 Bananas 5 Bananas 5 Potatoes 1 Butter 5 problem is not the only one to study. Idiosyncrasy, appetite for certain foods, distaste for others, and personal experience must all receive due consideration. The appetite for certain foods varies much at different periods of life. Fat is abhorrent to many children, and their lives and digestions are much troubled by the parental, but unscientific order to “clear up their plates.” In later years the same persons will welcome fat and need it. Sugar again is loved by children, scorned in middle age, when its place is often supplied by wine or beer, and is again welcomed and of great value in old age, for it helps much to maintain the failing heat of the body, to keep the home fires burning. Good cane-sugar at all stages of life seems to act as a special food, or at any rate stimulant, to the heart muscle; given in large quantities it often gives a failing heart a new lease of life. The digestibility of food is not governed entirely by its chemical composition. Twice cooked meat must contain nearly as much potential nourishment as once cooked, but experience tells most of us that we digest it with difficulty; and if the digestion of a food is not perfect, there is more unwholesome waste product to be cleared away; there is impure blood circulating in all our organs, but we feel it perhaps more in our brains; the lethargy, the depression, the irritability that we all recognize as the accompaniments of indigestion, all stand as cause and effect. Again hot fat and cold fat must contain the same constituents, but many can do well with