produced in every garden, and that improvements of the most remarkable kind are yearly occurring in consequence. Experiments are, however, it may be supposed, sometimes made without the operator being exactly aware either of the precise nature of the action to which he is trusting for success, or of the limits within which his experiments should be confined.

Cross fertilisation is effected, as every one knows, by the action of the pollen of one plant upon the stigma of another. The nature of this action is highly curious. Pollen consists of extremely minute hollow balls or bodies; their cavity is filled with fluid, in which swim particles of a figure varying from spherical to oblong, and having an apparently spontaneous motion. The stigma is composed of very lax tissue, the intercellular passages of which have a greater diameter than the moving particles of the pollen.

When a grain of pollen comes in contact with the stigma, it bursts and discharges its contents among the lax tissue upon which it has fallen. The moving particles descend through the tissue of the style, until one, or sometimes more, of them finds its way, by routes specially destined by nature for this service, into a little opening in the integuments of the ovulum or young seed. Once deposited there, the particle swells, increases gradually in size, separates into radicle and cotyledons, and finally becomes the embryo,. that part which is to give birth, when the seed is sown, to a new individual.

Such being the mode in which the pollen influences the stigma and subsequently the seed, a practical consequence of great importance necessarily follows, viz. that in all cases of cross fertilisation the new variety will take chiefly after its polliniferous or male parent; and that at the same time it will acquire some of the constitu

tional peculiarities of its mother.* Thus, the male parent of the Downton Strawberry was the Old Black, the female a kind of Scarlet; in Coe's Golden Drop Plum, the father was the Yellow Magnum Bonum, the mother the Green Gage; and in the Elton Cherry the White Heart was the male parent, and the Graffion the female.

The limits within which experiments of this kind must be confined are, however, narrow. It seems that cross fertilisation will not take place at all, or very rarely, between different species, unless these species are nearly related to each other; and that the offspring of the two distinct species is itself sterile, or if it possesses the power of multiplying itself by seed, its progeny returns back to the state of one or other of its parents. Hence it seldom or never has happened that domesticated fruits have had such an origin. We have no varieties raised between the Apple and the Pear, or the Quince and the latter, or the Plum and Cherry, or the Gooseberry and the Currant. On the other hand, new varieties obtained by the intermixture of two pre-existing varieties are not less prolific, but, on the contrary, often more so than either of their parents; witness the numerous sorts of Flemish Pears which have been raised by cross fertilisation from bad bearers, within the last twenty years, and which are the most prolific fruit trees with which gardeners are acquainted; witness also Mr. Knight's Cherries, raised between the May Duke and the Graffion, and the Coe's Plum already mentioned.

It is, therefore, to the intermixture of the most valuable existing varieties of fruit that gardeners should trust for the amelioration of their stock. By this operation the pears that are in eating in the spring have been

In early crosses between distinct species this is particularly manifest; but in those of varieties long domesticated it is less apparent, the distinctions between the parents themselves being less fixed, and less clearly marked.

rendered as delicious and as fertile as those of the autumn; and there is no apparent reason why those very early, but worthless sorts, such as the Muscat Robert, which usher in the season of Pears, should not be brought to a similar state of perfection.

There is no kind of fruit, however delicious, that may not be deteriorated, or however worthless, that may not be ameliorated, by particular modes of management; so that after a given variety shall have been created, its merits may still be either elicited or destroyed by the cultivator. In this place those practices only need be considered that tend to improvement.

Some fruits of excellent quality are bad bearers: this defect is remedied by a variety of different methods, such as, 1. By ringing the bark; 2. By bending branches downwards; 3. By training; and, 4. By the use of different kinds of stocks. All these practices are intended to produce exactly the same effect by different ways. Physiologists know that whatever tends to cause a rapid diffusion of the sap and secretions of any plant, causes also the formation of leaf buds instead of flower buds; and that whatever, on the contrary, tends to cause an accumulation of sap and secretions, has the effect of producing flower buds in abundance. This circumstance, which at first sight seems to be difficult to account for physiologically, is no doubt to be explained by the difference between leaf buds and flower buds themselves. In a leaf bud, all the appendages or leaves are in a high state of development, and the central part or axis, around which they are arranged, has a tendency to extend itself in the form of a branch as soon as the necessary stimulus has been communicated to the system by the light and warmth of spring. In a flower bud, the appendages or leaves are in that imperfectly formed, contracted state, which we name calyx, corolla, stamens, and pistilla; and the central part

around which they are arranged has itself no tendency to elongate under the influence of the usual stimulants. Hence, a flower bud, or flower, is nothing but a contracted branch; as is proved by the occasional elongation of the axis in flowers that expand during unusually hot damp weather late in the spring, becoming branches, bearing sepals and petals instead of leaves. It is, therefore, easily to be understood why, so long as all the motions in the fluids and secretions of a tree go on rapidly, with vigour, and without interruption, only rudiments of branches (or leaf buds) should be formed; and why, on the other hand, when the former become languid, and the parts are formed slowly, bodies of a contracted nature, with no disposition to extension, (or flower buds,) should appear.

It will be found that the success of the practices above enumerated, to which the gardener has recourse in order to increase the fertility of his fruit trees, is to be explained by what has just been said. In ringing fruit trees, a cylinder of bark is cut from the branch, by which means the return of the elaborated juices from the leaves down the bark is cut off, and all that would have been expended below the annular incision is confined to the branch above it. This produces an accumulation of proper juice; and flower buds, or fertility, are the result. But there is a defect in this practice, to which want of success in many cases is no doubt to be attributed. Although the returning fluid is found to accumulate above the annular incision, yet the ascending sap flows along the alburnum into the buds with nearly as much rapidity as ever, so that the accumulation is but imperfectly produced. On this account the second practice, of bending branches downwards, is found to be attended with more certain consequences. The effect of turning the branches of a tree from their natural position to a pendulous or a horizontal one is, to im

pede both the ascent and the descent of the fluids in a gradual but certain manner. The tissue of which branches are composed is certainly permeable to fluids in every direction; and there can be no doubt that the vital action of the vessels of a plant is performed both in the natural and in an inverted position. So long as that erect direction of the branches which is natural to them is exactly maintained, the flow of their fluids, being subject to no interruptions, will take place in the freest possible manner; but the moment this natural direction is deviated from, the vessels become more or less compressed, their action is impeded, and finally, if the inversion is perfect, it becomes so slow that an accumulation of the proper juices necessarily takes place through every part of the system.

One of the objects of training is to produce the same effect. Branches are bent more or less from their naturally erect position; their motion, in consequence of the action of winds upon them, which is known to facilitate the movement of the fluids, is totally destroyed; and hence arises the accumulation of proper juice which is necessary to their fertility. Nor is the influence of the stock of an essentially different nature. In proportion as the scion and the stock approach each other closely in constitution, the less effect is produced by the latter; and, on the contrary, in proportion to the constitutional difference between the stock and the scion, is the effect of the former important. Thus, when Pears are grafted or budded on the wild species, Apples upon Crabs, Plums upon Plums, and Peaches upon Peaches or Almonds, the scion is, in regard to fertility, exactly in the same state as if it had not been grafted at all. While, on the other hand, a great increase of fertility is the result of grafting Pears upon Quinces, Peaches upon Plums, Apples upon Whitethorn, and the like. In these latter cases, the food absorbed from the earth