Mr. Editor, - I shall premise by saying, I have no practical knowledge of the management of green-houses. "If but one kind of plants were in a house, and the proper amount of heat were not exceeded,'ventilation' would not be necessary." Page 275, June number.

Do not plants gather most of their ammonia and carbonic acid from the air. If as I suppose, the ammonia and carbonic acid in the atmosphere will in a short time become exhausted, will not the house require a " change of air," to enable the plants to obtain their proper amount of these gases.

Do not all plants obtain a portion, perhaps the greater portion, of their nourishment from the atmosphere?

Persons in recommending the use of the wheat drill have said, "Wheat planted in rows is enabled to take advantage of the' better circulation of air, thereby gathering more ammonia, which is stored in the plant as nitrogen".

Does your humble student understand you properly 1 Yours, etc, June, 1861, Syracuse, N. Y. Ventilation.

[We are much pleased with your questions, and should be glad to have many more of the same kind. They show that, though you may have no practical knowledge, so called, of the management of green-houses, you have some conception of the organic forces which go to the formation of plants. Plants do take up ammonia and carbonic acid freely from the air; but in a green-house these elements will not soon become exhausted; indeed, they will never become exhausted under any ordinary good treatment of plants, though the house were shut up very much closer than we suggested. You seem to have an investigating mind. Go to a green-house, examine its structure, look at the soil the plants are growing in, and think of all the changes that are constantly going on in the soil, the plants, and the atmosphere; think, too, of the food daily supplied to the plants, and then let us know your conclusions. You will not find us backward in aiding you in your investigations. The increased fertility of drilled wheat is undoubtedly owing to the increased surface exposed to the air; sown broadcast and thick, the air can not circulate so freely among the stalks. If you look again at our remarks in the June number, you will find that we call for air in motion and plenty of room.

These are essential for the full development of most plants. - Ed.]

Peter B. Mead, Esq.: Dear Sir, - The apparent pleasure with which you reply to the various inquiries of the readers of the Horticulturist encourages me to ask information in reference to the best work - practical and theoretical - on Gardening; comprehensive, reliable, and recent. Loudon is regarded as good authority, but his Encyclopedia contains many pages of little practical use in this country. Copeland, in his "Country Life," has collated a great mass of matter, but he runs a lightning train, and your foot barely touches the platform at a station before "all'aboard," and off he flies to other and diverse themes: a rare jumble of real jewels and bits of poor brass. How about Mcintosh's "Book of the Garden? " Is there a late edition of this work, and can you recommend it? Is there anything better? - where can I obtain it, and the price?

Please to direct me also where to find practical, working plans of Hot-houses, and the best method of heating them. Above the din of the Boiler war recently waged through the pages of the Horticulturist, you urged the promise of a future adjustment of the vexed question. I am confident that my memory is not at fault, and so have been waiting to find the thing done in plan and section. I have Leuchar's " Hot-houses," and could scarcely say too much in its praise as a philosophical treatise on light, heat, and ventilation, - on the atmospheric and hy-grometric phenomena of glass structures. But ten years have made many changes in the construction and interior arrangements of buildings of this kind. We would avail ourselves of the new if good - of the old if better. Pardon me; I trespass too far on your time, and can but beg your indulgence as of one long since made an acquaintance through the press, and regarded as a friend. Very sincerely yours, R. M. L.

[The pleasure with which we answer correspondents is real as well as apparent; the only trouble is, that we get so many we know not which to answer first. To answer them all promptly is a physical impossibility. Nevertheless, send them along; we would not miss them for ten times the trouble they give us; for they often enable us to supply an item of information useful not alone to him who asks, but to a thousand others. Loudon is very useful to have at hand as a book of reference, but you want something different Copeland does run a race with his readers, and generally outstrips them; but he leads them a pretty race. Mcintosh is good, but costly. The price will not be less than $18. We do not know of a late edition. Thompson is also good, but likewise costly. It will probably cost you $8. These are both capital works. Among older works for practice, there are Bridgeman, Buist, and others, which will cost you but trifling sums, and may be read with profit. As to such a work as you want on the construction of Hot-houses, etc, there is none that we know of. There are two in preparation, one of which is by Mr. Ellis; but they will neither be published during these war times. No publisher will now even look at a manuscript.

We would gladly give our articles on the " vexed question," and some others requiring illustration, but there is a difficulty in regard to the cuts which we can not well explain here. They will come yet in this or some other form. Thank you for your friendly allusions: we like to be brought into close sympathy with our parishioners, - Ed].

Dear Sir:- Can you give us any aid upon a point perhaps new?

I have a stout Concord grape vine, almost six years old, upon an open trellis. This vine was entirely unhurt by the past winter, which killed six Isabella vines on the same trellis. On May 10th the swelling of its buds first became apparent. On that day, or the next, I observed a small greenish black beetle, about half the size of a lady-bug, upon every bud. They remained eleven days, and then every one disappeared. I did not attend particularly to their operations until two or three days after their disappearance, when I found that every bud was pierced through by a little blackened hole, as if by a hot wire. Some of the buds were turned almost inside out.