Mr. De Jonghe, of Brussels, has been writing lately much about his favorite pear-tree, and comes to the following conclusions respecting the Regeneration of varieties, so much talked about. He says: -

"From what has been already stated, it will be understood that varieties cultivated in climates analogous to that in which they were raised, will, in general, retain their characters, provided the trees are planted in a suitable soil, and treated in a proper manner.

"If the causes of degeneration are to be ascertained, they may be sought and found: -

"1. In the use of improper stocks, which have no affinity with the graft.

"2. In the use of grafts badly selected, either taken from the lower part of very young trees, or from others weak and affected with various diseases.

"3. In the use of grafts grown in an artificial manner.

"4. In a mode of cultivation unsuited to the nature of the variety.

"5. In planting a variety in soil which is either too poor and too shallow, or too heavy, cold and moist.

"6. In want of attention, in consequence of ignorance of the first elements of a rational mode of culture.

"With respect to the first three causes, we have touched upon the principal points connected with them on several occasions in previous articles, and it would be superfluous to revert to them. Concerning the fourth, it is evident to every practical man that a normal degree of vigor, and, consequently, a good crop of perfect fruit, can only be obtained by allowing the tree to take that form which is most in conformity with its mode of vegetation. If that form is constantly restricted by premature pinching, or by too severe pruning, the tree bears a few small, cracked, gritty fruits, becomes barren, and is eventually destroyed. This is not owing to degeneration, but to a want of skill on the part of the cultivator. Nor can we attribute the cause to degeneration, when bad fruit is gathered from a tree planted in a soil which is too strong, compact, and moist It is not reasonable to seek from the soil that which it cannot give.

"We have seen a plantation of more than 100 pear-trees, comprising about 80 of the best varieties of pears. These trees were confided to one who is known to be an able cultivator. They were all trained in the same form - that of a dwarf pyramid - upon the free stock, and upon the quince. On the 15th of June, 1856, the 100 trees had not 200 pears on them. The premature pinching, performed, in a season different from the ordinary run, had caused a disordered vegetation, from which, of course, the trees Buffered, and, in consequence of which, they were not able to set their fruit. Moreover, the ground where the trees were planted was covered with a rather thick layer of horsedung, and this preventing the action of the air and sun upon the soil which covered the roots, the trees were unable to profit by the beneficial effects of the solar rays upon the ascending sap. If these trees remain weakly and barren, is that result to be attributed to the circumstance of the varieties treated in this way having reached the period of degeneration?

"That fruit-trees," he concludes, "are disposed to degenerate in consequence of the time they have been in existence, we do not believe".