By the action of light on leaves, the crude sap undergoes certain chemical changes which fit it for the nourishment of new parts; the trees should not, therefore, be shaded by others, but fully exposed to light. Circumstances which may tend to render the leaves less efficient, should also be avoided or prevented - such as a situation exposed to boisterous amount of organised sap will also be deposited in the tissue of the wood, than if the tree had borne fruit; this will give rise in the following spring, to rigorous branches and well developed leaves; it will also contribute directly to the growth of the fruit. Early in spring, the plants should be top-dressed with a compost as above. Numerous blossoms will now be produced, all of which should be destroyed, excepting about four or six bunches. By reducing the quantity of fruit, we increase the size and improve the quality of that left; a fact well understood and turned to account by some cultivators, but not, I fear, sufficently understood or practiced generally.

When the fruit is set, if the weather should prove dry, liquid manure may be applied with advantage; one part of pigeons' or fowls' dung, with three or four parts of water, is a powerful and prompt fertiliser; after being mixed it should be allowed to settle, and the clear liquid used. This watering should be continued more or less, according to the nature of the season, till the fruit shows signs of ripening - water should then be withheld, or the quality of the fruit may be injured. Fruit of the best quality being always obtained when the latter part of the summer is dry and sunny. The growing points of the young shoots may now be nipped off, with a view to add still farther to the size and quality of the fruit When the berries are ripe, the seeds should be washed free from pulp in milk-warm water - dried on paper, and suspended in cotton bags, in a dry room, till the time of sowing.

As soon as all danger from frost is past, the seeds may be sown thinly in rows, in a good light soil; when two years old, the trees may be transplanted to where they are to bear fruit, and they should be planted at such a distance apart, as that the foliage of one will not interfere with or shade that of another. If the branches are too crowded, some of the weakest may be cut clean out. The aim should be to have as great a breadth of foliage as possible to the light, with a view to hasten the period of fruit bearing.

By this mode of cross-breeding, different varieties of the pear or other fruits may be grown together, instead of a quarter of a mile apart. If trees are set out purposely for cross-breeding, no blossoms should be allowed to perfect their pollen; all should be early destroyed, excepting those to be operated upon. It is not, however, absolutely necessary, though advisable, to plant trees specially for this purpose. A healthy young tree, already in full bearing, may be used; it should be suffered to bear only a very moderate crop of fruit the year preceding the experiment. A branch may then be selected on the south side, all the flowers on the branch to be destroyed, excepting those to be cross-fertilised; these I would enclose in net or gause bags, to protect them from insects, and possibly from the ingress of adventitious pollen. When the fruit is set, it should be again well thinned all over the tree, and such other means resorted to as seem best calculated to add to the size and quality of the fruit.

There is a tendency in the seedlings of all highly improved fruits to revert to the original condition of the species, which can only be prevented by judicious selection and crossing, combined with high culture; comparatively few varieties deserving permanent culture will bo obtained, even with the best management - but the chances will evidently be much in his favor, who diligently avails himself of those means which the practice of the most enlightened cultivators, founded on a knowledge of the functions of the various parts of plants, has proved to be successful.

I noticed that two correspondents were boasting of the number of good varieties of peaches and pears which had been raised in the states, compared with the quantity of seedlings grown. I suspect that much of the credit of this is due to the climate, and that in our endeavors to improve many kinds of fruit, we shall have an advantage over most European nations especially over England and German v. where cross-breeding fruits has hitherto been most practiced. A given species of plant requires a certain range of temperature, and a certain amount of light, to enable it to grow in a healthy condition, or yield fruit of the greatest excellence; an excess or deficiency of heat and light, being alike injurious.

The gooseberry, strawberry, apple, and perhaps the cherry, are perfectly at home in England; they are grown there in great perfection, and there many valuable varieties have originated. But the pear, generally, seems to require a somewhat higher temperature. Several of the fine Flemish varieties do not ripen well on standards in ordinary seasons, and fruit from a wall, though large and handsome, is never so highly flavored as that ripened on a standard. Peaches, again, grown in England at great expense, chiefly under glass, and with artificial heat, are poor and insipid, compared with the delicious fruit which may be had so cheaply in New-York. If, therefore, it is a matter of so much importance that the fruit we wish to save seed from, should be made to acquire a high degree of excellence, it is apparent that in several of the states at least, ordinary culture will afford peaches far superior to any that could be raised in England by the most skillful garden^r. Our high summer temperature, and dry atmosphere, may be imitated, but the brilliant sunshine, the bright light, on which the quality of the fruit so much depends, is inimitable.

This should be a matter of great encouragement to the improvers of the more valuable kinds of fruit in this country - favored so much by climate, judicious selection and crossing, with improved culture, they can hardly fail to be otherwise than successful.

. While on this subject, perhaps I may be permitted to quote from one of the letters I had the pleasure to receive from the late Andrew Knight, a few remarks respecting the kinds of fruit he considered yet capable of improvement.

After giving me a humorous account of an interview with a grower of large gooseberries in Cheshire, he says, "I lament that the improvers of the gooseberry did not in preference, select the Red Currant. Culture has always a tendency to render fruits less acid, and to some extent, more tasteless, and the currant, on that account, promised a wider extent of improvement than the gooseberry. I think it not very improbable that the Red Currant might be made by successive generations, and proper culture,a sweet, perhaps a very sweet fruit. The Green Gage Plum is the cultivated sloe. And I do not doubt that the pun-gently acid fruit of the Berberry might be changed into a very saccharine fruit. The apple and gooseberry alone, of our fruits, have, I think, been shown in the greatest state of perfection, nearly what they have the power of acquiring in the climate of England; and of the plum and common cherry, we have many, or more properly, several fine varieties. To the improvement of the Morello Cherry, a totally distinct species, no attention has been paid.

With the pear, probably much may yet be done, but I fear the pear assumes its highest state of perfection in the warmer parts alone of England; as a fruit for the press, in such situations, I think it capable of affording a very fine wine fluid, far preferable to the wretched mixture often drank in England under the name of wine."

I have been glad to learn from the pages of this Journal, that many are now endeavoring to raise improved varieties of fruit. Gardening is allowed to be one of the most delightful amusements which can occupy the leisure hours of man - but pleasing as the ordinary culture of the plant may be, it is a tame and monotonous pursuit, compared with the pleasure to be derived from raising new kinds of perennial flowers or fruit from seed. The comparative uncertainty of the results of our experiments has its charms. In ordinary gardening, we know that the flowers and fruit of next summer will be like those of the it produces its flowers or fruit, it is an object of great interest, and a source of much speculation to the experimenter; mare mind is in the work, than in ordinary gardening - greater skill is required - more correct habits of observation, and a more intimate and extensive knowledge of cause and effect. And not only may the pursuit be recommended as a refined amament, or for the pleasure it is capable of affording, but it may be recommended as a commercial speculation.

There is, doubtless, ample room for improvement yet - more valuable varieties of fruit than any we now possess, will yet be obtained, and to say nothing of the pleasures of hope to be enjoyed by the way, there is a fair prospect of ultimately receiving an adequate return for the time and labor expended. Within twelve years from the time of proving the fruit, an improved variety might be introduced into every garden of the United States, and in a country where fruit growing is a matter of so much importance, it must be a source of gratification to the successful experimentalist, to be conscious, that even by his amusements he may have contributed to some extent, to the welfare of his country and fellow men. John Townley.

Port Hope, Columbia Co., Wis

Many thanks to our new correspondent in Wisconsin. We recognise him as a well known cultivator, who has seen the best practice on the other side of the Atlantic, and shall be glad to hear from him again. Ed.