“The analogy between fruits and leaves,” says A. de Jussieu, “is as much shown in their nutrition.as in their outward characters. Fruits, like leaves, though in a less degree, when acted upon by light, take up carbonic acid from the surrounding air, and throw off oxygen; during the night, on the contrary, they take up oxygen and throw off carbonic acid. Their life passes through the same phases; their tissues, at first soft and rich in juices, gradually solidify, and at a certain period begin to dry up, changing their green hue for some other, either that of the dead leaf, or one of the various tints, analogous to those assumed in autumn by certain leaves; the withered pericarp remaining attached to the tree, or falling to pieces, drops to the ground.”

Fig. 227.—Achænium of Corn Centaury.

Fig. 228.—Achænium of the Ranunculus.

Fig. 229.—Samara of the Elm.

Fig. 230.—Samara of the Maple.

Fig. 231.—Caryopsis of Wheat.

Fig. 232.—Haricot Pod.

Fig. 233.—Follicle of the Aconite.

Fig. 234.—Follicle of the Aconite.

Fig. 235.—Pyxidium of Henbane.

Fig. 236.—Siliqua of the Gilliflower.

Fruits are divided into two great sections—Dry Fruits and Fiesuy Frurts.

Dry Frutrs.

There are some among the dry fruits which open their shell at maturity to allow the seed to escape; others, on the other hand, remain always closed up. Thence arises the division of dry fruits into dehiscent and indehiscent. The fruits of the Dandelion, Chicory, Buck-wheat, Corn-flowers (Fig. 227), and Ranunculus (Fig. 228), are dry and do not open. The single seed that they contain adheres only to the pericarp; this kind of fruit is called achenium, from a, and yaww, “I open.” The Elm has for its fruit an achenium; but being surrounded with a folded membrane, something like wings, it is called samara. Fig. 229 represents a section of the samara-of the Elm; Fig. 230 the samara of the Maple. The fruit of Wheat, Barley, Oats, &c., is, like the achzenium, dry and indehiscent; but the single seed that it encloses adheres to the pericarp, so as to form one body with it. This fruit is called caryopsis, from kapva, “ wall-nut,” oye, “appearance.” Fig. 231 re- ‘presents the fruit, or caryopsis of Wheat. What a variety there is among dry fruits in their mode of opening! Some open with two valves, each carrying, on one of its edges, a row of seeds. Such are the pods of the Pea, Bean (Fig. 232), and other legumes. Others split up longitudinally on one side, and, in opening out, take the form of a leaf, carrying seed on its two edges; this is called a follicle; of this sort is the Aconite (Figs. 233, 234). Some dry fruits open in two parts by a circular horizontal chink, so that the upper part of 7. *1—Capmie of thePeggy: the fruit is detached like a lid. This kind of fruit is called pyxi-

dium, from pyxios, “a box.’ We see it in the Red Pimpernel and Henbane (Fig. 235). In others, the pericarp comes away in two valves, which, by théir fall, uncover a frame formed by the placenta furnished with their seed; this kind of fruit is called s¢dzqua, a pod or husk; the fruit of the Gilliflower is of this sort (Fig. 236).

Can anything be more ingenious than the plan of opening in the capsule of the Poppy (Fig. 237), or of the Field-Poppy? In these instances dehiscence takes place by means of a certain number of small reflex valves disposed in a circle on the flattened top of the fruit. The seeds in it are very numerous; but, in consequence of the beautiful arrangement just mentioned, they only fall; one by one, when the capsule is bent over by the wind, thus forming a kind of natural seed-drill. The fruit of the Foxglove (Digitalis), Fig. 238,

Fig. 238,—Capsule of Digitalis. which is also a capsule, opens with two valves, by the severance of the partitions in it, and each valve corresponds with a carpel; this is called septicidal dehiscence. 'The capsule of the Tulip (Fig. 239) opens with three valves, each valve corre

Fig. 239.—Fruit of the Tulip. Fig. 240,—Fruit of the Sandbox-tree.

sponding with the two halves of the carpel, and has a partition im the middle. This is called loculicidal dehiscence.

In some plants the scattering of the seeds is assured by means rather difficult of explanation. Every one ‘ _ knows that by merely touching the fruit of the Balsamines their valves are suddenly £; thrown back, and the seeds are dispersed, with great force. This peculiarity has given to one species of this order of plants the common name of Touch-me-not, and the generic name of Jmpatiens.

The capsullary and woody fruit of the Sandbox-tree (Fig. 240), an American tree of the order Euphorbiaceae, is composed of from twelve to eighteen cocci, which having become desseccated, open suddenly at the rig. 241—Fruit of the back, with two valves, and are detached from meer their axis with a kind of detonation. These fruits have actually been surrounded with iron wires, yet the force with which they expand has been such that the valves have been separated from each other. We will take our last example from a nearer source; the seeds of the Geranium (Fig. 241) are enclosed in little membraneous cells, which are inserted in the lower part of an axis, which is elongated and supported by a filament coming from the summit. At maturity, this filament bends in a scroll or spirally, and lifts with it the case with the seed contained inside. Thus the fruit of the Geranium, or Crane’s-bill, met with in the woods and green lanes, resemble a sort of candelabra with five branches, hung from the summit of a central column.

Fuiesuy Frutrs.

When the parenchyma of the fruit is largely developed, and it swells with juice, the fruit is said to be fleshy. Man derives from this kind of fruit so great a part of his nourishment, that he has exclusively styled the trees furnishing it fruit trees. This singularly illogical use of the term might lead to the inference that the Apricot, the Peach, the Apple, and such like trees, alone produced fruit. There is an obvious disagreement in this case between science and sentiment;a plants bear fruit.

Fleshy fruit is green in the first phase of its development. It then, like all the green parts of vegetables, gives out oxygen during the day, and carbonic acid in the night. But its bulk soon increases, and it receives through its peduncle the moisture and other substances indispensable to its growth. During this first period, the principles immediately soluble take their rise, and their proportions increase as the fruit is developed. These soluble bodies are—tannin, the organic acids, which vary with the fruits, malic, citric, or tartaric acid preponderating in some; sugar, gum, and pectine in others. The formation of pectine, the substance from which the jel/y of our household delicacies is prepared, is the result of a sort of reaction of the acids on a substance insoluble in water, alcohol, and ether: a substance which almost always accompanies the cellulose in the tissue of vegetables.

Sugar proceeds from the modification of certain neutral matters, such as gum and starch. In fact, starch exists in large quantities in some green fruits, but it completely disappears at the time of ripening. It is extremely probable, therefore, that it is the starch which is transformed into sugar (glycose) under the influence of acids. Tannin itself, existing in almost all green fruit, is not found in the mature state, but seems also to be changed into . glycose under the influence of acids.

The absence of acidity in fruit is the most curious fact attending its maturity. It has been stated that this disappearance is not owing to the saturation of acids with mineral bases, that the acids are not hidden by the sugar or mucilaginous matter existing in the ripe fruit, but that they are really destroyed during the ripening process. Tannin disappears first, and then the acids.

The moment when the tannin and acids have disappeared is that in which the fruit is most delicious; in a short time the sugaT itself disappears, and the fruit becomes insipid. About the period of maturity, fruits exhale carbonic acid. They no longer disengage oxygen during the day; they breathe, so to speak, after the manner of animals. Fruit at last undergoes a third modification; it becomes mellow. This new change has the effect of expelling from the fruit certain principles which belong to it. A Medlar, for example, at first very acid and astringent, loses its acid and tannin, and becomes

eatable when it becomes mellow. But the great difference established between the ripening and mellowing of fruit is, that the latter state is only manifested when the skin of the fruit, being somewhat decayed, the air has been able to penetrate the cells of the pericarp, colouring them yellow, and partly destroying them. We need not mention here the important part played by fleshy fruit in the production of alimentary beverages. The juice of the grape, having undergone fermentation, becomes wine; the fermented juice of numerous varieties of apples and pears yield cyder and perry, and almost every known fruit yields its own peculiar product. It is in the fleshy fruits that we can most readily distinguish the three parts constituting the pericarp, that is to say, that portion of the fruit which forms the walls of the ovary. These three parts are, tracing them from outside, the epicarp (emi, “over,” kaozoc, “ fruit”), an epidermal membrane varying in thickness;_the mesocarp (uésoc, “middle,” kxapzoc, “fruit ”’), constituting ordinarily the flesh and pulp of the fruit; and the endocarp (évdov, “ inside,” kaoroc, “fruit”), often forming the kernel, but the consistency of which varies, as we shall soon see.

As the ovary results from the physiological transformation of a leaf, and as the fruit is nothing but a ripened ovary, we may consider the epicarp and endocarp as representing the two epidermes of the leaf, and the mesocarp as the parenchyma of this original leaf. Most practical botanists only admit two classes of fleshy fruits, the drupe (stone fruit) and the berry. The Peach, Cherry, Plum, Medlar, and Cornel, are drupes; the Grape, Gooseberry, Apple, Orange, and Pomegranate, are berries.

All these fruits are more or less fleshy or pulpy. They are besides indehiscent, but there are in drupes one or more kernels, which are wanting in berries.

Let us first take a glance at the drupes. In the Peach, the Cherry, and the Plum, resulting from the ripening of a simple and Superior ovary, it is easy to distinguish three parts, first, an exterior skin, more or less thick, smooth, or hairy, or covered with a waxy secretion, known as the bloom; this is the epicarp: Second, a thick, pulpy, succulent flesh; this is the mesocarp: M 2

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