pass out into the broth, making it rich and nutritious. When the stew is allowed to simmer for several hours on the back of the stove, the meat itself becomes tender and readily digestible. The addition of vegetables makes it a most nourishing and palatable dish.

63. Boiling meats. When the meat itself is to be eaten, and the broth is not to be used, the whole piece should be plunged into boiling water for a few moments. In this way the protein on the surface is quickly coagulated, and the crust thus formed prevents the loss of the meat juices. The temperature of the water should then be reduced somewhat below the boiling point by pushing the kettle toward the back of the stove, and the meat should then cook slowly until it is done. A piece of meat, when cooked in this way, is tender and juicy throughout.. If, however, the water is kept at the boiling point (212° F.), the meat may be easily torn apart, but the fibers are found to be hard and stringy.

64. Roasting and broiling. The best method of cooking the flesh of animals, if the broth is not desired, is by roasting or by broiling, since smaller percentages of the nutrients are lost than is the case in boiling. The outer layer of protein must, however, be coagulated at once, and for this purpose a very hot fire is needed.

When the piece to be roasted is small, the high temperature should be maintained until the meat is cooked. A large roast, on the other hand, after the outer covering has been coagulated, requires a slower fire and a longer time; meat is not a good conductor of heat, and a hot oven would scorch the outside before the central mass could become thoroughly cooked. A better crust is formed on the outer surface of the roast if the meat juices in the pan (mostly fat) are frequently poured over the surface of the roast. This is called "basting."

The starches, which are

65. Reasons for cooking vegetables. present in large quantity in foods of vegetable origin, are usually inclosed in cells, the walls of which are formed of indigestible cellulose. Hence, before starch can be digested, it must be freed from this cellulose envelope. This is largely accomplished by cooking,

which causes the starch grains to swell. The cell walls are broken open in this way, and when the grains burst, a larger surface is exposed to the action of the digestive juices (Figure 21). This is strikingly shown in popping corn. The crust of bread is more easily digested than the softer parts, and toasting bread increases its digestibility, because this browned starch (sometimes called soluble starch) requires less change before it can be used by the body.

66. Boiling vegetables. Experiments have shown that a good deal of nutriment is lost by boiling vegetables in water. Much of

FIG. 21. A, cells of raw potato with starch grains inclosed in the cellulose walls. B, cells of a potato well steamed and mashed; starch grains have been burst by the heat.

this waste may be avoided, however, if one heeds the following directions: (1) vegetables should be cooked as far as possible in their peels, for these outside coverings keep the sugar, proteins, and mineral matters from being drawn out by the water; (2) if the vegetables must be peeled and cut up, the pieces should be relatively large, as a smaller surface is thus exposed to the water; (3) the amount of water should be as small as possible, and the vegetables should be cooked rapidly, in order to give less time for the solvent action to take place.

67. Bread making. When bread is made, water (or milk), butter, salt, sugar, and yeast are added to flour. After the mixture has been stirred together, a sticky mass of dough is formed, which, in

a warm place, begins to rise. This is due to the fact that the yeast cells change the sugar into alcohol and carbon dioxid. Bubbles of gas are thus imprisoned in the sticky dough. While expanding and seeking to escape, the gas makes the solid mass pcrous. After the bread has risen sufficiently, it is kneaded in order to break up the large bubbles and in order to distribute the gas throughout the dough. When the bread is baked, the alcohol and carbon dioxid pass off into the air, leaving the bread light and digestible.

VI. FOOD ECONOMY

68. Importance of food economy. It is said that in a large proportion of American families more than half the total income is spent for food, and that the remainder of the income must serve for rent, fuel, clothing, doctor's bills, and other expenses. Hence, any saving that can be made in the annual food bill of a family should result in a surplus which may well serve as a nucleus of a saving's bank account, or may be used in improving the home surroundings or in securing wider means of education and enjoyment. The average American, however, is far from economical in the matter of foods. In the first place there is often extravagance in the purchase of food, and in the second place foods are frequently wasted in the home.

69. Comparative cost of foods. (Home study.) The chart shown in Figure 22 exhibits (1) the cost price of each of the foods represented, (2) the weight of the food that may be purchased for 25 cents, and (3) the weight of the solid food substances (except mineral matters) that may be purchased in each food for 25 cents. Note at the top of the chart the short vertical lines that indicate 1 pound, 2 pounds, etc., of solid nutrients; hence, if 25 cents is spent for wheat flour, about of a pound of protein can be secured, of a pound of fat, and about 61⁄2 pounds of carbohydrates.

FIG. 22.-Economy in the purchase of foods. Prices in this chart were those in the year 1900. Compare with prices to-day. (U. S. Department of Agriculture.)

1. Name the foods represented in Figure 22 that are derived from animals; name those obtained from plants.

2. On the average, can larger amounts of the animal or of the vegetable foods represented on the chart be purchased for 25 cents?

3. Bearing in mind the relative work and expense in producing animal and vegetable foods suggest some explanations for the answer you have given to question 2.

4. Which one of the foods on the chart would you buy if you wished to get the largest amount of solid nutrition for 25 cents; that is, which food is the most economical?

5. From which kind of food would you get the smallest amount of solid nutrients? Name other foods on the chart which are more expensive per pound than the one that you have just named.

6. Which of the three kinds of beef named on the chart would be the most economical for soup or stew?

7. Name three classes of food substances needed in the diet of the average American engaged in moderate work (see last line on the chart), and estimate the weight of each that is needed during a day.

8. Which food on the chart comes the nearest to supplying in the right proportions all the nutrients named in 7? In the food you have named which kind of food substance is not present in sufficient proportion?

9. Why is it better to eat a variety of foods rather than any one kind?

10. Suggest a reason why meat and potato should be eaten together; bread and butter.

70. Economy in the purchase of foods. The animal foods, we have just learned, are considerably more expensive than the staple foods of vegetable origin. Hence, in an economical household the proteins needed by the body should be largely obtained from vegetable foods like bread, corn meal, and beans. If this plan were followed, a con