By pruning at the rising of the sap, we induce in trees, barren through over-luxuriance of growth, a flow of that sap from the roots, which of the roots. It is only when the buds are already considerably developed, and the leaves have acquired some consistency, and their stomata or breathing pores are well organised, that the growth takes place which directly forms fruit-buds. Having admitted the fact that the first flowing sap of the roots determines the vigor or health of the tree; all diminution of this increases then the relative proportion of the sap of the leaves, [rather the sap elaborated by them] and consequently, the chances of fructification. To render this operation more efficacious Mr. Rubens makes, at the time of the risings of the sap, a first pruning, which removes all badly-placed or superfluous branches, and afterwards he thins out the buds upon the more feeble shoots.

This early pruning hastens the starting of the tree and makes it vigorous. Thus in diminishing, previous to the rising of the sap, the number of buds that it is to nourish, those which remain receive along with the sap originally destined for them, that also intended for buds which were removed; the shoots are consequently more vigorous, and are developed sooner, because a great increase of sap causes a more prompt development of the buds than a less abundant flow. On the contrary a late pruning weakens and retards the tree, although it disposes it to bear fruit; for the sap of the roots in the early spring is carried directly to the terminal bud and to those nearest to it. In a late pruning those buds are removed to which was directed the largest supply of sap; a great loss of sap is thus effected, so that all that preponderance of sap calculated to produce excess of growth being lost, the fructifying food collected or digested by the leaves, has the preponderance; moreover, this method retards vegetation, since the tree is deprived of its most vigorous and advanced limbs, and some time must elapse before the buds which remain can reach the same condition as those which were cut off; by this delay, the flowering time is also retarded, and consequently the tree has less risk to suffer from the sudden variations of spring temperature.

Thus, it is by impairing the strength and vigor of the tree, that a late pruning makes it fruitful.

It should be remarked, that late pruning should only be employed upon very vigorous, healthy subjects. We have seen it applied to vines of only moderate vigor, and although it preserved their shoots from a late frost, yet, the following year, their crop was a feeble one from being exhausted the year before. It may, besides, answer to restore an equilibrum in a tree, whatever its shape, by an early pruning of the feeble branches and a late one for those which are too vigorous. M. A. Puvis. - Revue Horti-cote