Ik the Horticulturist for September of last year, there appeared a very interesting article, from the pen of a lady, upon the natural history of the Pear Slug. I refer to it here, in order to make a slight correction in one particular - a correction, important only as the account is not strictly exact. "Their eggs," she says, "are placed, singly, within little semicircular incisions through the skin of the leaf, and generally on the lower side of it." This account is also given in dole's American Fruit Book, and I am sure I have seen it elsewhere.

I inclose two leaves taken from a young pear-tree, which, you will observe, are covered with what appear to be small, perforated, white scales lying promiscuously all over and upon the upper surface. These are the remains of the eggs from which the young slugs have passed to their work, the perfect egg appearing simply like a perfect scale. It has been for my interest to watch, the advent of these creatures for some years past, and I have found the first evidence of their coming to be the appearance of these scales, placed superficially upon the upper surface. I have never discovered any incision in the leaf, nor even an accidental deposit, in a single instance, upon the lower surface. There are evidences of nearly a hundred of these eggs having been deposited upon each of the leaves which I send you; and, from their number, you will readily and correctly surmise that the de-structiveness of the insect, even in the first four hours of its existence, must be very great Though the lower leaves of the tree are those chiefly upon which the eggs are deposited, yet, as you can judge from the sample before you, an entire tree would be speedily divested of its foliage, if the insects, as they increase in their capacity for destruction, "were left unmolested.

Happily, if attended to in season, though their number be countless, as they were in the nursery from whence these leaves were taken, they can easily be arrested in their progress by the liberal application of slaked lime. It is by no means essential, however, as I see it universally recommended, that it be applied "when the dew is on." A moment's reflection will convince any one that (it being the creature and not the leaf that the lime is designed to assail) the dew must be unimportant if not an actual hindrance to its operation. Whatever lime is arrested by the dew-drops, becomes inert, and speedily hardens into a harmless mass, which the slug may pass over or avoid, at pleasure. When the leaves are dry, on the contrary, the lime which lodges upon them will be shaken off by the first agitation in the air, and a portion of it will be likely to find its way to the slimy back of some depredator that had hitherto escaped unscathed. Thus far, therefore, the presence of the dew interferes with the full execution of the design.

As great things are made up of small, so let the facts here stated, if found (as they are believed to be) " fixed" ones, take their position in the great aggregate of exact knowledge.