Transplanted trees are, until re-rooted, in the same situation, nearly, as trees cut down or rooted up and left on the surface of the ground - that is, they must relv mainlv on the sap existing in the cells before removal. Now it is plain that the more of buds and leaves there are on a tree, the greater will be the demand upon its stock of sap or nutrition, and vise versa. Hence the reason for recommending to reduce the tops of trees at the time of transplanting. For this reason we can not transplant deciduous trees safely while in full foliage. Even Strawberry plants root better by having a portion of their leaves removed;• and hence the use of bell-glasses and other contrivances to prevent evaporation from the leaves of newly-inserted cuttings. A tree transplanted with a small number of roots, or damaged roots, and a branchy top, will suffer from the evaporation of the leaves, just as a cutting with leaves would if it were freely exposed to the air, though perhaps not to the same extent Some trees will bear planting with smaller roots and larger tops than others - such, for instance, as the Poplar and Willow, and all those that root easily and rapidly, and have large sap-vessels through which nutriment absorbed by the roots can pass quickly to the leaves.

But we must remember, too, that leaves are necessary to the growth of roots. It is true that new roots are formed in the absence of leaves. We can see this illustrated in the case of early autumn-planted trees or cuttings: yet these roots would not attain any considerable development, nor survive long without the action of the leaves; for these may be likened to the animal stomach, in which the indispensable process of digestion takes place. No matter how abundant or healthy may be the roots, or how liberal the supplies of nutriment presented to them, if the leaves be not present to draw it upward and assimilate or digest it, growth can not continue - the roots will cease to lengthen, and ultimately perish. This.is forcibly demonstrated in the case of trees that have been stripped of their foliage by insects, or some accident, - the roots cease to grow; but as soon as new leaves begin to appear, new roots are formed simultaneously: and if one side of a tree be stripped of its foliage, the roots more directly in connection with that side will cease to grow until new leaves appear. In propagating plants from cuttings, it is necessary, in many cases, and indeed in almost all cases where young wood is used, to leave a certain number of leaves.

Cuttings that root without leaves are those of a soft nature, having large cells or sap-vessels full of organized matter or tissue capable of developing roots and sustaining them until the leaf-action commences.

From all this we see how important are the leaves, and how easy it would he by excessive pruning to hinder rather than promote the formation of roots. There is a medium which should be aimed at in pruning, to induce growth after removal. If the roots are much injured, or naturally meagre or defective, a very small number of active buds should be retained, just sufficient to stimulate and sustain circulation of the fluids. In such cases it may be necessary to cut back every young shoot to one or two eyes. Where the roots are abundant and sound, it will suffice to cut out the weak inside shoots, and shorten the stronger ones about one-half. In doing this, a large number of buds are removed, and whatever force there is in the tree is thrown into the remaining shoots, and young wood will be formed where we should have had nothing but leaves if the tree had not been pruned. The growth of young wood last spring, we shall find that the roots are in proportion to the number and strength of the young shoots.

The great object in pruning to promote growth is to direct the sap into a smaller number of channels, and thus increase its force. If a tree, for example, has 500 leaf-buds to draw upon its sap, and we cut away 400 of them, the remaining 100 will of course receive a far greater proportion than they would have done, and will consequently be enabled to make new wood; and experience teaches us that young shoots with their large cells, luxurient leaves, and great vital activity, act far more powerfully on the roots than the small, lean foliage of trees merely living but not growing. We know how cutting back acts upon stunted trees. A three or four years old Apple or Pear tree, for example, if cut down nearly to the ground, will, in one season, make a growth equal to that of two or three seasons under ordinary circumstances; and this is simply because its whole vital force is concentrated in one point The sap rushes there, and large cells are formed immediately, in which a rapid and powerful circulation takes place.

All operations upon trees should be performed cautiously, because whatever produces a sudden or violent change in their condition, cannot fail to be attended with a derangement of their wisely and beautifully adjusted organization, and this derangement must be more or less injurious to their healthy existence. Every man who takes his knife in hand to mutilate a tree, should bear this in mind, and weigh carefully the consequences of every cut We intended to have referred to the opinions of experienced and skillful arboriculturists on this subject, but we can not at present devote more space to it. What we have said will, we trust, induce reflection and observation on the part of some who have heretofore been too indifferent.