hundred families in the United States, that fresh fruits make up 3.8 per cent. of the total food, and supply 2.5 per cent. of the total carbohydrates. To this must be added the dried fruits used, so that all together 4.4 per cent. of the total food material and 3.7 per cent. of total carbohydrates is from fruit. As far as digestibility is concerned 80 per cent. of the protein, 90 per cent. of the fat, and 95 per cent. of the carbohydrates are digested, thus comparing favorably with the digestibility of vegetables.

From some experiments carried on at the California Ag. Experiment Station and elsewhere in which fruit and nuts constituted the sole diet of the individuals, the conclusion was reached that it is possible to supply the necessary protein and energy from these foods, although in many cases the expense per day per capita is greater than with a mixed diet. In this case the protein was derived mostly from nuts and olives and much of the carbohydrates from the fruits.

THE USES OF FRUIT

It is not the intention to discuss here the relative value of vegetable and animal foods, or the claims of "vegetarians" and others, but it is pertinent to say that under the conditions obtaining in the United States, a liberal addition of cereals and vegetables to a fruit and nut diet would decrease the bulk of the food necessary, make possible a greater and more pleasing variety of food, and lower the cost. Fruit is good, but fruit only is bad.

It is of interest to note that in tropical countries fruits grow in much greater abundance and variety than in the north, and in the polar regions practically no fruit at all is grown. Also that the fruit is produced in the temperate zone in the warmer months of the year. These facts point to the conclusion that fruits and vegetables are naturally better adapted for use in warm climates and during the warm season, and animal products where the temperature is lower.

A judicious use of fruit is without doubt extremely beneficial,

especially if one conforms in his selection to the particular needs of the system. Usually fruits are somewhat laxative, although some berries, like blackberries, contain enough tannin to act as slight astringents and have a constipating effect. Fine-seeded berries have à constipating and irritating effect, and on that account should be avoided. On this account the fruit juice made into a jelly is a much more suitable diet for invalids than the whole fruit made into jam.

The organic acids of fruits are admirably adapted to assist digestion by increasing the flow of saliva and indirectly of the gastric juice. They also increase the secretions of the liver, pancreas and the mucous lining of the intestines. When taken into the blood the vegetable acids render it less alkaline by combining with the alkaline salts of the serum. In fact the salts of the organic acids are changed to alkaline carbonates. These are some of the reasons why fruits are considered so valuable as antiscorbutics and for use in general debility and anæmia. They are also used to great advantage in gout and rheumatism.1 Furthermore the natural combination of acids, sugar, pectin, mineral, salts, and water that is found in fruits stimulates the appetite, and helps in the movement of foods through the energy machine that we call the alimentary canal.

Fruits to be wholesome should be ripe. They are often more agreeable when ripened on the tree, although there are exceptions to this statement as in the case of many varieties of apples and pears. If the fruit is unripe any injurious effect can be prevented by properly cooking.

COOKING OF FRUITS

Although it often happens that the cooking of fruits rather diminishes than increases their agreeable flavor yet this process has many advantages when it is applied judiciously. On account of the conditions under which fruit is often gathered, 1 Foods, Origin, Manufacture and Composition, Tibbles, p. 594.

stored or sold, its surface is liable to be contaminated with insects, insect larvæ, worms, or injurious bacteria. In some cases it is customary to remove the outer covering before the fruit is eaten, but in the case of berries and some other fruits, this is impossible.

The process of cooking sterilizes the fruit, and protects the consumer, especially from the bacteria on the surface, which might induce disease if taken into the system.

As there is cellulose and starch in fruits, cooking softens and modifies these and renders them better fitted to be taken into the system. (See p. 12.) Some fruits, as quinces and some varieties of pears, plums and crab apples, are so hard and unpalatable that they are always cooked before they are used.

Frequently fruits and berries are cooked without the addition of water, for they contain about 85 per cent. of water, which simply needs to be set free as "juice" in the process of cooking. In baking apples there is, of course, some loss in weight, due to evaporation, but there is no loss in nutrients, if the juice that exudes is served with the apples.

There seems to be an impression that cooked fruit is sourer than that which is raw. This may be partly due to the physica. condition of the cooked fruit, which would allow it to come more intimately in contact with the nerves of sensation. Hot fruit seems to give the impression of sourness more than that which has been allowed to cool, but this may be due to the stimulation of the surfaces with which the food comes in contact. Another reason for this impression of sourness is given by Sutherst,1 in the case of gooseberries, by the fact that the skins contain more acid than the pulp, and in the cooked portion the skins are included, while if eaten raw the skins are rejected. If cane sugar is present in the fruit, it is changed to fruit sugar (see p. 95) by prolonged cooking in the presence of a vegetable acid, and fruit sugar is not as sweet as cane sugar.

It is often said that fruit is sweeter if the sugar is added after 1 Chem. News, Vol. 92, p. 163.

cooking than if it is cooked with the fruit, and although this is theoretically true, it has been shown that in the cases tested, although the product is slightly less sweet if the sugar is added at the beginning rather than the close of the operation, the difference is too small to be of practical importance.1

OVERRIPE FRUIT

As the fruit becomes overripe it changes in composition, and soon begins to decay. This decay is caused by fungi or molds, which obtain a start most rapidly wherever the skin is broken, or the fruit is bruised. This spreads very quickly to the sound portions of the fruit, and soon spoils its agreeable odor and flavor, even in the parts not yet affected by decay. As previously noticed (p. 209) with the overripening the fruit begins to ferment; that is, the sugar is changed to carbon dioxide and alcohol.

WASHING FRUIT

It is a common practice with housewives to wash fruits before serving, and experiments have been made which show that the amount of material removed in this process is really quite small. Berries and soft fruits should only be washed just before they are served, otherwise the damp fruit will quickly mold. All the fruit that is vended from stalls or on the city streets is especially exposed to the dust and filth of the street, and to being handled by the hands of the vender, which are often none too clean, and should therefore be as thoroughly washed as is possible. In the case of apples, oranges, bananas, etc., the skin can be removed, but plums, grapes and similar fruits should be washed before being eaten. In many States sanitary regulations are in force to prohibit the sidewalk display of food products, unless they are raised 6 inches above the floor and protected from flies, dust, and other contaminations. Dried fruits such as dates and figs that are eaten raw, should always be thus protected.

1 1 Jour. Home Econ., 2, 1910, No. 1, p. 94.

CHAPTER IX

ORCHARD AND VINE FRUITS

Although there are not less than one hundred and forty species of fruits known in the United States, not more than forty are grown commercially. It is remarkable to what an extent and how quickly scientific methods have within the last few years been applied to fruit growing in this country. Advanced ideas in regard to spraying, pollination, fertilizing, pruning and intensive cultivation have been very successfully put into actual practice.

ORCHARD FRUITS

APPLE

Following the classification of fruits given on p. 208, the first is the apple (Pyrus malus). This is the typical and in fact the most important of the "pome" fruits. The "core" is the ripened 'carpels," as they are called, and the pulp is the thickened "receptacle" on the top of which the "calyx" is borne. Botanically the apple belongs to the Rose family, which includes also the pear, quince, medlar and loquat.

It is probable that the apple as cultivated in the United States is not a descendant of our native crabs, or wild apples, but comes from the wild crabs of Europe,' but important varieties of apples may no doubt at some time be developed from our native crabs. Some excellent varieties of crab apples have already been cultivated.2 Some authorities believe that both wild and cultivated apples were found in Europe from prehistoric times, while others think they were early introduced into Europe from western Asia.

1 Farmers' Bull. No. 113.

2 Origin of Cultivated Plants, De Candolle.

The Evolution of Our Native Fruits, Bailey, L. H.