The tree in the open field, exposed on all sides, requires an ample supply of both. It grows moderately; its trunk is stout; its wood is firm, compact, and hardy; its bark thick; its roots numerous, wide-spread, and powerful; its branches ample, evenly disposed, and nicely balanced. There it stands, fitted out completely to meet the requirements of its position.

There is valuable instruction here for us all. Nurserymen know that when their rows of trees are thinned out - say one-half or three-fourths removed - the remainder, instead of pushing upward, as they had done before, begin to throw out numerous branches, the trunk thickens, and the roots spread and strengthen rapidly. One season's growth, under such conditions, gives them such a hold of the ground that it requires three or four times the amount of labor to remove them that it did the year previous, when they stood very close. On this account such trees, although generally regarded as culls, prove most successful when transplanted, and are preferred by experienced planters, even if they be defective in form.

Trees rapidly grown, forced with a rich soil, and drawn up in the shade and shelter of close nursery rows, are as ill-fitted to stand the shock of removal into the open ground, exposed to the full force of the sun and wind, heat and cold, as are the tall and slender trees that have grown up in the heart of the forest. The young trees have the advantage in being more plastic: they suffer, and almost die; but the inherent vigor of youth enables them, in many cases, to weather the storm. But even where they do survive the shock, it is severely felt, and shows itself in the slow and feeble growth which follows removal.

In gardens and sheltered grounds this difficulty is of less account; but how small a number of all the trees planted enjoy the benefits of shelter! Scarcely any one dreams of nursing and hardening their trees for a period previous to their final planting; and yet, in a multitude of cases, it would be a prudent and profitable course - and so especially with all the more rare, valuable, and delicate trees, shrubs, and plants. Even in England, where the climate is much less rigorous and changeable than ours, such proceedings are recommended and practiced. In a work which we noticed some time ago,* it is recommended, in planting valuable and delicate evergreen trees, to plant them first in some sort of open boxes that would allow of their removal, once or twice a year, from a more sheltered to a more exposed place, until they would finally become sufficiently hardened to bear the exposure of their permanent situation.

It is quite unnecessary to multiply illustrations showing the advantages which young trees derive from being reared in open situations, sufficiently exposed to admit of the growth of side branches, and acquire what we call hardiness. Our nursery rows are in general too close, and the trees too close in the rows; we grow three or four times too many on the ground. We are aware that it would add considerably to the cost of the trees, to give them so much more space; but would it not be a saving for purchasers to pay one-third or one-fourth more for them? We very much fear that we shall have no very extensive reform on this head until people become much better informed on the subject of arboriculture - when, instead of looking for the tallest trees in the nursery, they will look for stout, well-rooted trees, that have been well exposed to the sun and air, and thus hardened and fitted to encounter the trials of a removal.

One reason why so few good pyramidal-shaped young trees are to be found in the nurseries, is their closeness. Although they are cut back, no stout side branches are produced, because of the want of a full share of light around the lower part of the trees; any shoots that do start out are soon smothered, and the entire growth is thrown into two or three shoots at the top. A good pyramidal tree can not be produced-we can not secure the first branches - without a clear space of two or three feet on each side; whereas, they usually stand within a few inches in the nursery rows.

Another advantage in giving trees abundant space, to which we have already alluded, is, that it promotes the extension of roots. In fact, whatever favors the extension of branches, also favors the roots; because they depend so much upon each other as to be co-extensive. But the soil has a powerful influence on the roots. In stiff, clayey soils, trees have bare, forked roots, and few fibres; and that, too, even when the growth of the tree is good. Such trees do not transplant well. Dry, friable soils, are more favorable to the growth of numerous fibrous roots, and trees taken from them transplant more successfully. Culture has a great influence on the roots, too. If the ground be kept continually clean and friable by cultivation around the roots, they become much more fibrous and better for transplanting than if the surface of the ground be permitted to harden into a crust, or to be covered with weeds or grass.

Having the trees thus properly grown in abundant space, dry friable soils, and clean culture, the next important point is to take them up properly; because, no matter how a tree is grown, if it be badly taken up it is not fit for successful transplanting. Trees are more universally injured - ruirwd - in this operation than in any other. We believe it is so in all parts of the world, for our trees imported from Europe are about as badly bruised and mangled as any we ever see at home. At the seasons of transplanting, nurserymen are generally hurried, and have to employ raw, untrained laborers, who know or care as much about roots as they do about conic sections. A man may stand over them, and show them, and talk to them until he is hoarse, and yet the roots will be cut and mangled. It really requires considerable skill and experience, and a great deal of care, to dig trees well. Some have long taproots that penetrate the ground deeply, while others spread widely near the surface of the ground. These different characters require different modes of proceeding. Some insist that it does a tree no harm to cut off some of its roots; but we hold that the roots should be taken out of the ground without the slightest bruise or mutilation, if possible.

The necessity for curtailing the tops would thus be obviated, and there would be some hope for the trees. We are utterly opposed to the lopping off both roots and branches of trees, and thus converting them into bare poles before planting. The generally commended proceeding of pruning or shortening the tops, is a necessity only because the roots scarcely ever escape injury in some way or other; and as leaves must receive a supply of nutriment through the roots, it is only reasonable that when the roots are reduced the leaves should also be reduced in a corresponding degree.

Then comes packing for transportation. The less the roots of trees are exposed to the air, between the time they are taken from the ground and the time they are planted, the better. This should never be forgotten. If roots be of any value, it can only be when they are sound and fresh. More than nine-tenths of all the trees planted have to be carried a greater or less distance from the nuraery, and consequently require packing; and many people, to save a little cost, will run the risk of having their trees ruined. We are satisfied that vast quantities of trees are lost from bad packing and exposure in transportation. It requires considerable skill and care to pack well. Very few of the European nurserymen can pack for America, as importers well know: and on this account we are always compelled to purchase at higher prices than we might do, in order to secure good packing; for if we were to get trees for nothing, they would be a hard bargain unless well packed. Good packing is equally essential in transporting trees from one part of our own country to the other, because we have great delays.

We can get a package almost as soon from Liverpool to New York as we can from New York to Rochester; so that parcels of trees should be always fitted up to go safely twice the distance intended, or twice the time that ought to carry them to their destination. What signifies fifty cents or a dollar per hundred, in the cost of securing trees for carriage, compared with running the risk of losing them or having them so damaged that they will not recover for years. Every man who orcders trees should say emphatically," Pack my trees in the best manner;" and nurserymen should be held responsible for this, as much, at least, as for the quality of the trees. Having now briefly called attention to what we consider a prevailing defect in the growth of young trees, that unfits them for safe and successful removal, and the necessity of care in packing for transportation, we shall hereafter take occasion to say something on planting and subsequent management.