There has probably never been a single species of fruit, which, in all its varieties, has attracted so large a share of attention in the same space of time, and absorbed so large a monied investment within that time, in the northern half of the United States, as the Pear; and I must be permitted to say, so far, with doubtful results. Within the last ten years, thousands of acres, in garden, lawn, and orchard, have been planted, and hundreds of thousands of trees have been transferred to these plantations. France, Belgium, Germany, and England, have contributed to them. Our own nurseries have been ransacked, and now and then one rooted out of pears altogether, to supply the demand; and nurse-rymen themselves, have gone into pear propagation with a furor little short of the multi-caulis mania of 1838, 9 and '40.

Yet the pear mania - if mania, a new-born zeal in the cultivation of one of the choicest and best fruits with which a kind Providence has blessed us, may be called - is a sensible mania; and under ordinary circumstances, would confer much luxury and enjoyment on our people. Yet there is one difficulty which it may be feared is like to dampen much of the ardor of those who have gone into its cultivation, and in many cases, to even extinguish not only their ardor and their hopes of pleasure and profit, but the very trees themselves, which have been the objects of so much expense, labor, and solicitude.

This difficulty is the summer blight, which is scattered all over our pear producing country; lighting here and there, as caprice, accident or soil; cultivation, locality or variety, may attract it, and scourging and destroying the trees, without regard to the most patient and watchful attempts of the cultivator to avoid its presence, or prevent its ravages. It would be a subject of painful, yet somewhat satisfactory interest, if, in answer to a gene ral circular addressed to every fruit-grower in the country, asking the result of his labors for the last ten years, each one would give a correct account of his success, and his mode of treatment of his trees, and of their present condition and prospects. It is to be feared that the balance of profit and loss would stand altogether on the wrong side of the ledger, and chiefly from the effects of the blight. And the worst of the matter is, that the cause and origin of the disease is as yet, altogether beyond our comprehension, and its cure past all our ingenuity. The causes of the cholera and the potato disease, are not more inscrutable, nor their remedy any easier of solution.

Hundreds of pages have been written upon the " pear blight," its causes, its prevention, its cure; and it stands just where it has always stood, a terror to the cultivator, and a certain scourge to his hopes. Although thus far, in my own small efforts, happily relieved from its ravages, I hope, with fear and trembling, that my young trees just budding into fruitfuiness, are not to be assailed; still, I shall not be susprised to see half of my trees stricken down by the destroyer, before another fall of the leaf.

In the month of August last, a gentleman residing in the valley of the Mohawk, paid me a visit, mainly to look at my pear trees, and to examine the soil and position where they grew, in inference to the blight. He spent several days in this vicinity and its neighborhood. He had taken a wide survey of the comities of central and western New-York, with an inspection of the principal pear orchards, in the intention, if the results of his observations were favorable, of locating himself in our best pear growing district, and commencing an orchard on a large scale. After be had returned home, I received a letter from him, saying, that in the finest fruit regions of western New-York, he had found the blight among the pears more or less fatal, and that hardly a locality of any extent appeared exempt from its and he was altogether in doubt of the success of his enterprise, if he should engage in it.

The pear trees in the immediate vicinity of Buffalo have, until the last two years, been almost quite exempt from the blight; and in the occasional branches which it struck, gave no alarm, from the unfrequency with which it occurred, and the slight extent of its stroke. Within two miles of the center of the city, on ahigh, undulating, sandy-loam soil, occasionally mixed with gravel, and the lower parts of it mixed with clayey-loam, but not highly charged with lime, are several fine fruit gardens. The extensive nurseries of Col. Hodge and the Messrs. BRYANT, are there, who have numerous large standard pear trees, which have for years produced a great deal of fruit, of several varieties. Close by them reside, also, Mr. Lewis Eatoh and Mr. Charles Taintoe, who several years ago planted fine orchards of pear trees, which had just began to be productive. These gentlemen are all good nomologists, and good cultivators, and were in high hopes that their trees, having so far escaped the blight, would remain free from it. But the last summer has been almost fatal to them.

Their orchard trees, on quince and pear stocks alike, were struck in almost every possible situation, and of almost every different variety of this fruit, until they now present, in their mutilated tops and branches, but a wreck of the luxuriance and beauty which but a year before they exhibited. Their hopes are dashed at once, and they have serious doubts whether they shall abandon them to their fate, or attempt to repair damages, and plant anew. It is, at best, a trying dilemma.

A gentleman who has resided for more than forty years past at Lewiston, on the Niagara river, told me, some years since, that he would never plant another pear tree. He had planted scores of them. He had given them the best cultivation, and the closest care - I know htm to be a good nomologist - but the blight had, one after another, taken off nearly all his trees, and no remedy which he could apply, and he had tried every thing he had heard of, could prevent it. The whole country between Lewiston and Lake Ontario, was alike in this particular, although it is, for other northern fruit, equal to any portion of western New-York. It lies below " the mountain," which constitutes the abrubt termination on the north of the "Onondaga Salt groupe," of the geologists, over which the Niagara is precipitated in its mil, to the level of Lake Ontario, and is on the " Clinton groupe" of recks, a decomposable red stone, mixed with alumina, shale, sand and lime, and hearing upon it a rich, heavy, wheat producing soil.

From the scarp of this " mountain," or table land, en both sides of the Niagara, running south almost on a level, to within a mile of Buffalo - all within the Onondaga Salt groupe - the soil is chiefly a heavy day-loam; and on this soil, as yet, the blight has scarcely been known, till within a year or two past. A few wilding trees, perhaps a mile above Tonawanda, which had been planted some thirty years ago, and bore abundantly, of a tolerably decent cooking and drying pear, have been struck with the blight, and pretty much destroyed. But they had neither care nor cultivation for many years past, being on a farm not cultivated, but under the skinning operation of tenants. Yet these were quite as well cared for as others which I know on both sides the river, in flourishing health and growth, bearing bountiful crops every year. My awn trees, both at my residence, and on my farm, still flourish, and have borne considerable fruit; but I tremble for their fate, equally on the stocks of the pear, and on the quince.

I would give a trifle to know if the old French Pear trees on the Detroit river, were ever struck with the blight. But they never seem to know anything in that region about their pear trees - or if they do, they don't tell of it - and we are not likely to be much enlightened from that quarter. The soil where they stand is much the same as that of the Niagara, I described to you in the Horticulturist a year ago.

This is a momentous question, as the politicians say; for could the pear trees now standing in plantations in this state alone, grow unmolested by the blight for twenty or thirty years to come, millions of dollars would be added to our wealth, and the hearts of their owners made glad with their abundant harvests. Why will not our pear growers relate their experience in the columns of the Horticulturist? The intelligence thus gathered would at least be interesting, if not consolatory, to those who feel concerned in it.