On pears this blight was more injurious by far. The branches not only died down to the lowest black spot, as was the case with the apple, but they continued to form black spots of bark still farther and farther down, even to the ground, when not arrested by amputation. It is worthy of remark here, that I had six pear trees, not grafted, upon whole seedling roots, and only six; of these, five out of the six, some ten years old, were almost entirely ruined.

The one not injured, in the spring I filled with sulphur, by putting it in a half inch hole, as I did some of my plum trees, merely to see if it would correct the disease of the leaf, of which I spoke in a former communication. Whether this did any good or not, I know not; but the fact was, every tree around it was sadly injured, while it wholly escaped.

Again, of several hundred plum trees in the same lot, known to be grafted on " entire seedling" roots, cot one was in the least degree affected with the blight through the season, though many of them stood in the midst of a young nursery of apples, all of which were more or less dead in their terminal branches. It should he noted, however, that a part of these trees were plentifully supplied with ashes, hones, 4c, when they were transplanted several years ago - though not all of them.

Toward the latter part of the season, I began to suspect that the disease in the pear tree was analogous to the erysipelas in the animal system - and as I had got tired of amputation, I cut away all the dead cor tide, or outer bark, as fast as it appeared,and left the inner bark untouched. The inner bark in such cases lived, and I see is alive now. On one tree, there was a blotch on the trunk two feet long, and some four to six inches wide, in which the cuticle appeared entirely dead, while the inner bark was fresh. I proceeded on the same principle as physicians do with erysipelas, and arrested the progress of the blotch, and thus far saved the tree. How it will do in the spring, I cannot say. I am sure this disease is unlike anything I ever saw before, and I am inclined to think it is of atmospheric origin, or proceeds from the presence of animalculae, and that it progresses by the same general law as erysipelas in the human system, and that peeling the dead corticle off as soon as it appears, and applying a weak alkaline wash, will arrest its downward and fatal progress; and also, that sulphur, as applied to plum trees for the curca-lio, may prevent it, if done early in the season.

But I only make these suggestions in the hope that they may stimulate others to a more extensive and satisfactory investigation of the facts in the case. All theories which I can form, are as yet quite unsatisfastory, while many of those proposed, are entirely at war with the facts as they appeared here, though they may apply well elsewhere.

By the way, the erysipelas has appeared more fatally in the human subject in these parts, within a few years, than was ever before known. Do the same atmospheric or other causes, conduce to both diseases in the animal and vegetable world? Let us observe and inquire. At all events, if no remedy is found, it will be useless to attempt to cultivate pears in this western country.

It should be noticed, however, that the only pear trees of twenty or twenty-five years old, in this vicinity, have stood for many years in an unbroken sward of blue grass, which is hard and compact. Some of these trees were somewhat blighted at the top, but far less than younger trees differently situated. One seedling tree in the same lot,.standing in a cultivated garden, about fifteen years old, showed not a single blighted leaf, while all others near it were blackened more or less.

It is certainly true here, that trees grafted upon entire seedling roots, and trees standing in a hard, tough, blue grass sward, have escaped all forms of blight as yet, for better than others, [which is partly owing to their making very moderate growth - instead of running into over-luxuriance, and partly to the grass protecting the roots from excessive changes - like mulching. Ed.]

The blight to which I alluded in a former paper, and which has heretofore prevailed here, starts from the south-west of the trunk and large branches, and spreads both upwards and downwards, while the leaves are still unaffected; and seems precisely like that form of blight which is described by your correspondent as killing his apple trees in Mobile, in the December No. of the Horticulturist. I cannot have been mistaken in calling this form of blight a severe scald - the facts here abundantly prove it. Beside, how do your advocates of the frozen-sap theory, account for the above case. Does frost kill ap-ple trees in Mobih? I apprehend they would be killed still worse in the same way, farther south, if their trunks were exposed to the scalding sun, continually drying the liquid sap into solid gum. But while the blight of former years thus began, and appeared to spread like a general mortification of the animal tissues, the blight of this year appeared to begin on or near the extreme twigs and small branches, at once affecting the leaves, while still the trunk and large branches were entirely sound - and spreading mostly downwards, first on the outer bark, like erysipelas, and not by a general simultaneous blackening and gangrene of the interior tissues, as in the other case.

Again, it frequently began on the most shady side of the tree, even where the sun never shown upon the branch; and while extreme heat is the only known cause to which I can ascribe the disease in this latter case - still it operated by producing a general paralysis of the functions of the cuticle, if at all, and not by a sudden scald of a particular part of the trunk, as in the former case. I have been thus particular and tedious, because it is, in my present view, as absurd to suppose all blights in trees are alike, as it is to suppose all fevers and inflammations in men and animals alike. It is true, a blight is a blight, and so a fever is a fever, whether produced by cold or heat, or miasma or surfeit, or starvation; but physicians find it quite convenient, after all, to distinguish between fevers and their causes, before they prescribe remedies - and that both frost, and heat, and miasma, and animalcule, and surfeit, and starvation may, in different localities produce different modes and forms of this balrful pear trcefivsr, has at least, been rendered sufficiently probable to awaken suspicion and inquiry. Let us try, therefore, to obtain accurate descriptions of its forms and modes in different places and seasons, as the only sure first step in a truly philosophical investigation.

It is certainly, however, about as dangerous here to trim a pear tree, or disturb the blue grass sward around it, as it would be to trim a boys' nose, hair and ears off, and lay him out naked to roast, in a hot summer's sun, thinking thereby to make him grow faster, or into better shape. To say nothing of our horticulturists, our most ordinary observers now know better here, though in many cases their knowledge cost them more than it is worth, for their trees are all gone.