Rice is rather meagre in nutriment; it contains but little phosphorous matter, with less carbon than other cereals, and is best and most generally employed as a diet in tropical countries.
Beans and Peas are rich in nutritious matter, and furnish the manual laborer with a cheap and wholesome diet.
The Potato is the most valuable of all fresh vegetables grown in temperate climates. Its flavor is very agreeable, and it contains very important nutritive and medicinal qualities, and is eaten almost daily by nearly every family in North America. Until very recently it, with the addition of a little butter-milk or skim-milk, constituted almost the sole diet of the Irish people. The average composition of the potato is stated by Dr. Smith to be as follows: Water 75 per cent., nitrogen 2.1, starch 18.8, sugar 3.2, fat 0.2, salts 0.7. The relative values of different potatoes may be ascertained very correctly by weighing them in the hand, for the heavier the tuber the more starch it contains.
Turnip and Cabbage are 92.5 per cent. water, and, consequently, poor in nutrition, though they are very palatable. The solid portions of cabbage, however, are rich in albumen.
It is evident that the quantity necessary to maintain the system in proper condition must be greatly modified by the habits of life, the condition of the organism, the age, the sex, and the climate. The daily loss of substance which must be replaced by material from without, as we have seen, is very great. In addition to the loss of carbon and nitrogen, about four and a half pounds of water are removed from the system in twenty-four hours, and it is necessary that about this quantity should be introduced into the system in some form or other, however much it may be adulterated. Professor Dalton states: "From experiments performed while living on an exclusive diet of bread, fresh meat, and butter, with coffee and water for drink, we have found that the entire quantity of food required during twenty-four hours by a man in full health and taking free exercise in the open air is as follows:
| Meat, | 16 oz., or | 11.03 lb. avoir. |
| Bread, | 19 " | 1.19 " |
| Butter or fat, | 3½ " | 0.22 " |
| Water, | 52 fluid oz., | 3.38 " |
That is to say, rather less than two and a half pounds of solid food, and rather over three pounds of liquid food."
Climate exerts an important influence on the quantity and quality of food required by the system. In northern latitudes the inhabitants are exposed to extreme cold and require an abundant supply of food, and especially that which contains a large amount of fat. On this account fat meat is taken in large quantities and with a relish. The quantity of food consumed by the natives of the Arctic zone is almost incredible. The Russian Admiral, Saritcheff, relates that one of the Esquimaux in his presence devoured a mass of boiled rice and butter which weighed twenty-eight pounds, at a single meal, and Dr. Hayes states that usually the daily ration of an Esquimau is from twelve to fifteen pounds of meat, one-third of which is fat, and on one occasion he saw a man eat ten pounds of walrus flesh at a single meal. The intense cold creates a constant craving for fatty articles of food, and some members of his own party were in the habit of drinking the contents of the oil-kettle with great apparent relish.
Digestibility of Food. Unless an article of diet can be digested it is of no value, no matter how rich it may be in nutriment. The quantity of food taken, will influence to a considerable extent, the time consumed in its digestion. The stomachs of all are not alike in this respect, and the subject of time has been a difficult one to determine. The experiments of Dr. Beaumont with the Canadian, St. Martin, who accidentally discharged the contents of a loaded gun into his stomach, creating an external opening through which the process of digestion could be observed, have furnished us with the following table, which is correct enough to show relatively, if not absolutely, the time required for the digestion of various articles:
| ARTICLES OF DIET. | Mode of Preparation. | Hours. Min. |
|---|---|---|
| Milk | Boiled | 2 00 |
| " | Raw | 2 15 |
| Eggs, fresh | " | 2 00 |
| " " | Whipped | 1 30 |
| " " | Roasted | 2 15 |
| " " | Soft boiled. | 3 00 |
| " " | Hard boiled. | 3 30 |
| " " | Fried | 3 30 |
| Custard | Baked | 2 45 |
| Codfish, cured, dry | Boiled | 2 00 |
| Trout, salmon, fresh | " | 1 30 |
| Trout, salmon, fresh | Fried | 1 30 |
| Bass, striped, | Broiled | 3 00 |
| Flounder, | Fried | 3 30 |
| Catfish, | " | 3 30 |
| Salmon, salted | Boiled | 4 00 |
| Oysters, fresh | Raw | 2 55 |
| " | Roasted | 3 15 |
| " | Stewed | 3 30 |
| Venison steak | Broiled | 1 35 |
| Pig, sucking | Roasted | 2 30 |
| Lamb, fresh | Broiled | 2 30 |
| Beef, fresh, lean, dry | Roasted | 3 30 |
| " with mustard, etc | Boiled | 3 10 |
| " | salt only | 3 36 |
| " | Fried | 4 00 |
| " fresh, lean, rare | Roasted | 3 00 |
| Beefsteak | Broiled | 3 00 |
| Mutton, fresh | " | 3 00 |
| " | Boiled | 3 00 |
| " | Roasted | 3 15 |
| Veal, fresh | Broiled | 4 00 |
| " | Fried | 4 30 |
| Porksteak | Broiled | 3 15 |
| Pork, fat and lean | Roasted | 5 15 |
| " recently salted | Raw | 3 00 |
| " | Stewed | 3 00 |
| " | Broiled | 3 15 |