some fruits are of the highest.value as articles of food, others are generally regarded rather as articles of luxury; yet the abundance of succulent fruits in tropical climates is a bountiful provision for real wants, contributing much to the health of the inhabitants. The coolness of succulent fruits renders them peculiarly grateful amidst the heat of the tropics; their temperature, when newly gathered, being much below that of the surrounding atmosphere.
Cultivated Pruits.—In its popular use, the term F. sometimes has almost the same signification as in the language of botanical'science; sometimes it is employed as almost exclusively designating the edible succulent fruits. We cannot attempt an enumeration of edible fruits; many will be found noticed. in other botanical articles; we can only here observe that they belong to many and very different natural orders, both of endog enous and exogenous, but chiefly of exogenous plants. We propose; however, to con clude this article by an enumeration of the principal cultivated succulent fruits, includ ing those which are important as articles of food or of commerce.
Nuts, and along with them some fruits which, although not botanically nuts, resem ble them in onalities and uses, will be noticed in a separate article.
Chemical Composition of principal knowledge of the composition of dlr ferent kinds of F. is due to the recent investigations of Fresenius, which are published in the Annalen der Chem& and Pharnzacie for 1857. In that memoir, he gives the results of upwards of 50 analyses of different fruits, including gooseberries, currants, strawber ries, raspberries, mulberries, grapes, cherries, plums, apricots, !peaches, apples, and pears. We select the following analysis as representing the composition of seine of our most important fruits—viz. (1) the gooseberry; (2) the grape; (3) the cherry; (4) the peach; (5) the apple; and (6) the pear. For the purpose of comparison, the free acid which is present, whether it be malic, citric, or tartaric (all of which occur in fruits), is calculated as hydrated malic acid.
Glucose and fruit-sugar or fructose, are described in the articles devoted to these subjects. Under the heading " Soluble Pectine, Gum, etc.," are included coloring mat ters, fatty or oily matter in a state of suspension, and organic acids in combination with bases. We shall endeavor to explain briefly the nature of the substances desig nated in these analyses as pectine and pectose. The term pectine matters is applied to a very widely distributed class of substances occurring in the vegetable kingdom, and especially abundant in fleshy fruits and in roots, but whose properties and composition require further investigation. The substance termed pectose, which is insoluble in water, occurs in plants, which likewise possess a ferment in solution which converts pectose into pectine, which is soluble in water, and is the main constituent of apple and other fruit jellies. According to Fremy, pectic acid, which is closely allied to pectine, is
formed in fruits that yield jellies (he has assigned formulas to both these substances, but they are not generally accepted).
The ratio in which acid stands to the sugar varies extremely. For a unit of free acid, the sugar is re resented by 1.63 in plums, by 3.00 in currants, by 4.37 in straw berries, by 4.93 in gooseberries, by 7.03 in damsons, ,by 11.16 in apples, by 17.29 in sweet cherries, by 20.18 in grapes, and by 94.60 in pears; the percentage of sugar is least (1.57 per cent) in peaches, and greatest (14.93 per cent) in grapes; while the percentage of free acid is least in pears (0.07 per cent), and greatest in currants (2.04 per cent.
Fresenius observes, that as all the fruits contain albuminous or proteine matters, they are serviceable as tissue-forming food; but the albuminous matters are present in such small quantity, that these fruits will not serve without other nitrogenous food to keep the body in health. Thus, to obtain an amount of albuminous matter equivalent to the contents of one egg, we must eat more than a pound of cherries, nearly a pound and a half of grapes, two pounds of strawberries, more than two pounds and a half of apples, or four pounds of pears. They are, however, of more use as respiratory or heat-giving foods. Fresenius calculates that 1 pound of starch (which is equivalent to about 5.5 pounds of potatoes), may be replaced by 5.4 pounds of grapes, 6.7 of cher ries or apples, 10.8 of currants, or 12.3 of strawberries. Fruits are, however, taken not so much for their amount of material nourishment, as for their vegetable salts (which are of great therapeutic utility), and for their agreeable flavor. In tracing the. connec tion between the flavor and the chemical composition of fruits, Fresenius finds that the former depends (1) on the ratio in which the acid stands to the sugar, gum, pectine. etc. (the last-named substances making the ratio in which the acid stands to the sugar; (2) on the presence and delicacy of the aroma; (3) on the proportions between the soluble mat ters, the insoluble matters, and the water; thus, we usually attach the highest value to those fruits which contain the largest amount of soluble, and the smallest amount of insoluble matters—a peach or a green-gage almost melts in the mouth, because these fruits are relatively poor in cellulose and pectose; while, on the other hand, bilberries represent the opposite extreme, and are rich in insoluble ingredients; (4) on cultivation, which is found to cause an increase in the quantity of sugar, and a diminution of the amount of free acid and of insoluble matters; (5) and on favorable seasons, which aug ment the sugar and other soluble constituents.