"Now, good digestion wait on appetite,

And health on both."

Shakspere.

Why we eat, what to eat, and when to eat it, are questions which all should be able to answer. That a man may eat his fill and yet be hungry is a well-known fact. What then is the reason ? It is certainly not the quantity but the-quality of food which satisfies; and often, indeed, it not only happens that what is one man's meat is another's poison, but it is also true that what is food at one season of the year or time of life, or in one climate, may be poison at another season or age or in another climate. Dwellers in the tropics thrive on fruits upon which the inhabitants of the frigid zone would starve, while the blubber and oil that completely nourish the Icelander would be fatal if eaten under the Equatorial sun. Even the same person requires fruit in the tropics and fat and oils in the frozen zones. The child requires food made up of different elements from that needed by the adult, and the food of a laborer in the field must differ from that of the student, who takes little exercise, and whose strain of life is heavy on the nervous system.

It is particularly important that those who are forced to practice rigid economy should know just what will best supply the needs of a family and how the most nourishment may be had at a minimum of expense. We are told by scientists that an adult requires daily eight and a-quarter pounds of dry food and water, with air necessary for respiration. The same amount is thrown off as waste, or in other words eight and a-quarter pounds is used up as fuel to keep the machinery of life in motion, and if that fuel is not forthcoming, death ensues. The better the oil, the better the light; and the more perfectly suited the food is to the wants of the system, the more vigorous will be the body, the more perfect the working of muscle, nerve and brain.

Food is first masticated, then digested. When it reaches the stomach it is at once acted upon by the gastric juice, which pours from the walls of the stomach. Consequently, anything that dilutes this fluid tends to retard digestion, and sickness follows. Therefore, it is a mistake to drink freely during mastication, or until some little time has elapsed after eating to allow the stomach to do its work unhindered. As the juices of the stomach act only upon the surface of the food which passes into it, it can readily be seen why light bread is more whole-some than heavy bread. Light, spongy bread is acted upon in every part because the gastric juice is able to penetrate it; and if all housewives knew this, they would not place the heavy, stale loaf on the table, "to save it." Truly, many a mother gives a stone when asked by her child for bread !

Fats of all kinds do not digest in the stomach, but require the action of the bile and pancreatic juice to make them available as carbon for living combustion. Only as fat is combined with other food is it a benefit to the system, and the use of more than can be. perfectly blended brings on indigestion and often excessive "heart-burning," to use a domestic term.

Food has primarily two functions - the repair of muscular waste, and the supply of the body with fuel to keep the temperature up to 980 ; and each is indispensable to health and strength. The chief part of our food goes to keep up this living warmth, and the balance, except small portions of mineral substances, such as sulphur and potash, goes to muscle and brain production. The secret of healthy food is to adapt it to the present needs of those for whom it is prepared. Foods are divided into three classes : the Nitrogeneous, in which nitrogen is the chief element, and which feed the muscles only ; the Non-nitrogeneous or Carbonaceous, which produce heat chiefly ; and those in which the first two are combined.

It is known that the body requires four to five ounces of food for heat to one for muscle, and this is the key to preparing food in different climates and for different occupations and conditions. The whites of eggs (pure albumen) are richest in nitrogen or muscle-providing food. The lean parts of beef, mutton, venison and game contain nearly as great a percentage - about fifteen parts in one hundred. Grain, peas, beans and the curd of milk are also rich in nitrogen, and if muscles were all that were needed, these would be almost perfect food. But for one ounce that goes to muscle, five ounces must go to heat, and this means Carbon.

Carbon, the heat producer, comes chiefly from starch, of which the vegetable kingdom is largely composed, Sago, tapioca, arrow-root and corn starch are almost pure starch, and desserts made of them are easily digested and contribute largely of carbon, but do not feed the muscles, except they be combined with eggs, milk, etc., in cooking. Consequently, children and working people who need to have their muscles fed should be fed on such things rather sparingly, unless muscle-making food has also been eaten. For the student, the aged and those who do not exercise much, these foods are most valuable, being easily digested and productive of warmth.

The following table shows the proportion of starch in common grains, etc.