Debilitants to be applied as preventives against over-luxuriance in bearing trees or plants disposed to excessive wood growth, or as remedies where the trees or plants are unfruitful by reason of the non-development of fruit-buds.

1. Stinting supplies of food - by confining the tree or plant to a pasturage of limited space, through means of root-pruning, or of stocks having a small system of roots.

2. Neglected cultivation.

3. Retarding the circulation, by bending the branches and destroying capiltarity.

4. Breaking the circuit of circulation during the growing season, and before the roots have received an equivalent in vigor and enlargement, for the supplies sent upward in the circulation.

It will be seen from the list of stimulants, that I enumerate two distinct processes of shortening-in; one, proper only between the growing seasons; the other at all times stimulating, in consequence, as I have supposed, of the parasitical nature of the parts removed. The bearing apple tree often exhibits striking proof of the parasitica 1 action of the fruit-bearing force upon the vigor of the tree, as also of the efficiency of shortening-in as a counteracting stimulant; for it often happens that during the growth and maturation of an excessive crop, not a particle of wood seems to be formed; indeed even the fruit-buds for the succeeding year, which generally lie at the point of the spur sustaining the fruit which is being matured, are often starved out, or rendered so feeble as to perish in the following winter. Whenever the terminal fruit-bud is destroyed in this way, wood growth, more frequently than otherwise, takes place from the first bud below or within the terminal bud thus destroyed. This is shortening-in, performed by removing a portion of the fruit-bud system, before the commencement of the growing season; one of the most unmis-table instances of this process, and of its efficiency as performed by accidental means, occurred under my observation in 1851, with two White Doyenne Pears upon quince stock, subjected on the first of May, when in full leaf and fruit, to 8 temperature of twenty degrees; every fruit, every leaf, and every bud was killed, and many fruit spurs sloughed off; but now those trees are covered with a vigorous wood growth, many branches exceeding a foot in length, although at the time of the frost, and for some years before, there was present that scantiness of wood growth common to the pear dwarfed on the quince when in bearing.

I have in a former number adverted to the effects of removing portions of this fruit system during the growing season, as witnessed in a course of experiments with the peach; but there is a plant in common cultivation whose history illustrates so forcibly the debilitating tendency of the seed producing system, and the manifest relief to the general vigor of the plant, consequent upon a removal of that system, whether sooner or later, in the stages of its growth, that I am tempted to advert it, although perhaps at the expense of that brevity proper for these numbers. I mean the tobacco plant, which, as every body knows, is cultivated for its leaves; but these leaves are grown large or small, thick or thin, at the will of the cultivator, who uses this same fruit or seed producing force as his chief engine of control. Thus, if a heavy and thick article is desired, the upright leading shoot, is pinched out before the slighest development of the seed system appears; in that case the top leaves, although very small at the time of pinching out, expand, and in well cultivated crops become the largest of the plant, and the whole system of leaves keeps up an active circulation with the roots till the approach of frost, constantly increasing in weight.

If, however, in the same field, other plants of equal thrift be allowed to grow until the embryo umbels which would ultimately crown them if permitted to flower, are fairly developed, or in planter's parlance, until the " button" is formed, before the leading shoot is cut off, no after care can make these leaves so large or so heavy as those upon the early topped plant; and what is more, the longer the process of heading down is delayed, the lighter will be the leaves. In the first case we sec striking evidence of the continued action and reaction between the roots and leaves of the wood-bud system, during the growing season; in the latter, strong proof that the fruit or seed bearing system never ceases to be a burden to the circulation, until it ceases to act. Cutting out, therefore, in whole or in part, the fruit bearing system, is, whenever performed, a species of exorcism; a freeing of the general circulation, in whole or in part, from the paralizing influences of that magical power, which during the mysterious metamorphosis termed a development of the fruit-bud system, as well as during its existence, seems to weigh like an incubus upon the general vigor of a tree or plant; and if Forsyth had based his claims to distinction and to national bounty, upon the fact of his having been the first who wrought miracles by the potency of this charm in rejuvenating old trees, by heading them back, and dressing the wounds with his peculiar composition - giving credit where it was due, instead of bepraising a compound of inert ingredients, and thereby perpetrating the egregious error of mistaking a trifling coincident for a most powerful cause, he would today hold rank among practical philosopher, instead of being consigned, as he is, to the companionship of humbugers.

As for the other processes listed in class No. 1, they all rest upon well known maxims, and need not be enlarged upon. Cutting back the wood branches after the close of one growing season, and before another begins, is lessening the number of individuals to be fed, without lessening the years' supply. Cultivation destroys rival feeders, and facilitates the passage of the roots in rambling for food, whilst manuring enables them to glean more food from a given extent of pasturage. All insects, fungi, or mosses, interrupt in some way the circulation, so that their destruction is at all times invigorating.

I regret to see by an editorial remark in the November number of the Horticulturist, that I failed to make myself understood in some comments upon Mr. Downing's method of shortening-in. I have not intended to say that shortening-in, as a means of preventing the tree from enfeebling itself, was either inefficient or improper. So far from it, I consider this process the means - nature's own means. The point I thought untenable in his practice, was prescribing this remedy somewhat as a panacea, and not as a specific Sometimes a peach tree, three years old, and even much older, has only wood-buds, or wood-buds and branches, in very great excess; to shorten-in these in February or March, to prevent their enfeebling themselves, would be defeating ourselves of what we most desired - if, as is the hypothesis, such trees would remain unfruitful until reduced in vigor.

L. Young.

Springale, Ky., Dec. 1851.