Although a novice in fruit-culture, I propose to state a few facts which I have learned by observation the present season, and propose a few questions for information from you.

I have a dwarf Pear tree (Duchesse d'Angovleme), set last season, which grew luxuriantly, and started finely this spring, and was in blossom, when we had quite a severe frost (not to the material injury of fruit blossoms), a few days after which the leaves on this tree turned black and dropped off. The limbs at the extremity became black, and black spots appeared at the base of the buds, And Although I cut away all the diseased parts the tree has not started, and will probably die. Was this caused by the frost !

The green aphis has made its appearance on some of my trees, and I have observed that they are found only on trees infested with ants, and find the ants collected on the leaves and shoots with the aphis. On applying the tobacco wash, the ants will collect on other parts of the trees, and the aphis will then appear in a day or two, and I have thus far found, without exception, that where ants infest a tree the aphis are found, and where there are no ants, no aphis can be found. Do the ants produce aphis. (1).

I observed the communication of Mr. B., of Kenosha, in the May number of the Horticulturist and will say that the bark-louse is found on trees obtained from nurseries here, and I find that on my trees they extend to the extremity of the last year's growth; and I have just been into an orchard of bearing size, and find the trees completely coated with lice from the ground to the extremity of the limbs. Can the wash you recommend be applied to all parts of the tree without injury! (2).

I had seen it stated that the bursting of the bark of Cherry trees at the West was probably caused by their rapid growth; and to guard against this, I set my trees in grass ground, and have not manured at all, but have kept the ground clean for several feet around the base, and mulched in the Bummer season, and they have grown very alow. I have a Black Eagle, that was set out two years ago, and has not grown a foot in that time, and does not exceed two inches in diameter, and the bark has cracked to the wood this season. A. 0. Babcock, - East Troy, Wis-eonein. (3).

(1.) The reason of your finding the ants and aphis always in company is, that the ants feed upon a sweet fluid discharged by the aphis. You will see this if you observe closely.

(2.) The wash recommended in the May number may be safely applied to all parts of the tree on which bark-lice may be found.

(3.) Rapid growth may contribute towards producing the malady known as the bursting of bark, but it is by no means the sole or chief cause. A tree, growing slowly, may have soft, imperfectly matured wood, as well as one growing rapidly; rapid growth is safe enough if made at the proper season - say June or July. The bursting of the bark is the result of injuries sustained by the freezing and thawing of winter. The vessels, or cells, become disorganized by expansion and contraction, and the sap becomes diseased. Cherry trees of a hardy nature, such as Dukes and Morellos, and those well sheltered from the sun and cold winds in winter, or protected by some covering, escape injury of this kind.