Part 38. Fruits Are Eaten For Their Sweet Or Acid Juices

38. Fruits are eaten principally for their sweet or acid juices, and thus differ in general from what we call "vegetables." Moreover, while "vegetables" are generally cooked, or at least are prepared for eating by the addition of oil, vinegar, mustard, or the like (as in the case of salads), fruits are more often eaten raw just as they are picked, except perhaps for the addition of sugar. As might be expected, however, the line between fruits and fruit-vegetables cannot be drawn with distinctness.

Out of the very large number of different kinds of edible fruits, we can here consider as examples only a few of the more important, namely, the apple, pear, quince, peach, plum, cherry, raspberry, strawberry, European grape, northern fox-grape, garden currant, muskmelon, watermelon, orange, lemon, banana, date, fig, and pineapple (see Figs. 91-111).

As already intimated, the most significant features of the chemical composition of fruits are (1) the presence in considerable amount of peculiar acids, (2) the predominance of sugar in the dry substance, and (3) the presence of useful salts. These chemical characteristics are shown on the chart. It will also be noticed that the proportion of proteid is very small except in the banana which, in this respect, is typical of a certain class of tropical fruits, including the date and fig, that form a highly important source of nutriment in the regions where they grow. Starch may be detected in the banana; in the more juicy fruits, however, starch is absent.

The highly attractive flavoring matters upon which our enjoyment of fruits largely depends, are present in such exceedingly small amount that chemical analysis can hardly take account of them. Nevertheless their importance as an aid to digestion is believed to be far from insignificant. As the fruit ripens, the various flavors and acids, and most of the attractive pigments, arise as by-products.

Fig. 94.-Peach (Prunus Persica, Rose Family, Rosaceoe). A, flowering branch. B, flower, cut vertically. C, diagram of flower. D, ovary, cut across to show the two layers of the wall, the outer (dotted) which becomes fleshy, and the inner (white) which becomes hardened as the "stone" or "pit"; and the two ovules of which only one commonly becomes a seed. E, fruit with flesh cut in half vertically, showing the rough "stone" or inner hardened part of the ovary wall. E, the "stone" broken in half to show the single seed within. (LeMaout and Decaisne.) The plant is a tree; leaves smooth; flowers pink, appearing before the leaves; fruit downy.

Fig. 95.-Plum (Prunus domestica, Rose Family, Rosacea). Fruiting branch (Nicholson.)-The plant is a small tree with hairy twigs; flowers like those of peach but white; fruit smooth and with a bloom, the stone slightly rough.

Fig. 96.-Sour Cherry (Prunus Cerasus, Rose Family, Rosaceoe). 1, flowering branch. 2, flower, cut vertically. 3, fruit, cut vertically. (Wossidlo.)-The plant is a rather low, round-headed tree with gray bark; leaves stiff and glossy; flowers white or reddish; mostly in advance of the leaves; fruit smooth, light or dark red. smooth, without bloom, sour or sometimes sweet in cultivation. This species together with the mazzard cherry (P. Avium) includes most of the varieties of cherry grown for their fruit.

Fig. 97.-European Raspberry (Rubus idoeus, Rose Family, Rosaceoe). 1, flowering branch and leaves. 2, flower cut vertically. 3, fruit. 4, floral diagram. (Wossidlo.)-An erect, prickly shrub; leaflets whitish beneath; flowers white; fruit dark red, yellow, or whitish. This species together with our wild red raspberry (R. strigosus) which is closely similar to it, have produced our cultivated varieties.