rotten, collapse, and either fill the cavity described to exist at the bottom of the stalk of the fruit, with a preternatural collection of putrid water, which quickly causes the stalk to decay at its base, and, consequently, the young fruit to fall off long before it even approaches maturity, or which, when the remains of the flower become pendulous, keeps the young fruit and its support so damp as to produce the same effects. But if, with a pair of very sharp scissors, the whole of the fleshy rays are remooved after the flower is fecundated, all this inconvenience is avoided, and, in most cases, the fruit will swell and arrive at maturity, especially if a little pollen be applied to the stigmas, with a feather or a bit of any soft substance.

This is a very simple contrivance, and it would seem obvious enough; but the cause of the failure in obtaining fruit being generally unknown, it is not surprising that the mode of removing the impediments to its maturation should have been also overlooked.

The figure, at the end of this communication, will serve to explain the peculiar structure which I have attempted to point

out.

Those who may desire to find a detailed account of the various kinds of granadillas, will do well to consult the Horticultural Society's Transactions, vol. iii. p. 99., where there is an excellent account of them, by Joseph Sabine, Esq., the Secretary.

ART. III. Remarks on the Effect of the Lombardy Poplar in Park Scenery. By Mr. JOHN THOMPSON, Landsurveyor and Pictorial Draughtsman.

THE Lombardy poplar is a tree, which, as applied to the science of arboriculture, is capable of producing not only the most noble and striking, but the greatest variety of effect; and

perhaps, there is no tree which has the misfortune to be in general so injudiciously planted. I have, therefore, sent you a few remarks founded upon the study of landscape composition, in which I do not intend to say any thing of the bad or good qualities of the poplar, but merely to consider it as a tall conical mass of foliage, which becomes of great import, when contrasted with the more useful and valuable round headed trees.

First then, it is a known pictorial rule, that all horizontal lines should be balanced and supported by perpendicular ones; -thus, the effect of a bridge or via-duct would be greatly increased by the assistance of poplars.

In the accompanying sketch, (fig. 1.) not only the lines of the

bridge are balanced and supported by the upright poplars, but lengthened and pleasing reflections are produced, which breaking the horizontal gleams on the water, continue a mass of lines intersecting each other at right angles, than which effect, nothing can be more simply grand and classical. This is ad mirably illustrated at Blenheim, where the poplar is an ac companiment of all the bridges, but more particularly at that via-duct, where the water first enters the park; this seen from the neighbourhood of the great bridge, forms a landscape of much beauty and purity. But the planting of the island is as inuch at variance with good taste: it is covered with tall poplars, forming a mass which seems too big for its base; and which mass, from its stiff and upright form, contrasts but badly with the varied outline of the surrounding wood and water. How much more agreeable it would have been to

have looked down from the bridge on a well-selected group of round-headed trees.

The poplar, therefore, would be advantageously planted wherever there is a continuance of horizontal lines; but they should be so arranged as to form a part of those lines, to seem to grow out of them, rather than to break or contrast with them in too abrupt a manner. In the case of a stable or other agricultural building, where the principal mass extends in length rather than in height (fig. 2.), it would be wrong to plant

them exactly before it (a), but they should be at the sides or behind. The poplar is very generally planted before the cottages and residences which are to be found on the roads a few miles from the metropolis; and, as forming a part of those residences, nothing can be worse: you may see six or eight poplars taller than the house, obstructing its view, and overpowering and diminishing it by their magnitude and stiffness, when a few low trees mixed with laburnums, lilacs, &c., would be so much more to the purpose, not but the poplars are well calculated to produce good effect as a whole, when the road is seen in perspective; but it is not to be supposed that general effect and public ornament have been studied by individuals. The poplar should also appear in all plantations and belts that are made with a view to picturesque effect (fig. 3.), but more

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particularly they should be introduced in a sparing but judicious manner in all pleasure-grounds; and they are quite in

dispensable in the formation of such groups as are intended to convey an impression of that grand and classical simplicity, which is, or should be, the first object in all ornamental planting. Another sketch, (fig. 4. a, b.) will be the shortest way

of showing the assistance which the poplars give to a group of trees. Here, though the mass (a) might be seen to advantage in some situations, when grouping with other objects, it is, when contemplated merely by itself, quite uninteresting from its dull and monotonous appearance; but add the poplars, as in (b) and you immediately create an interest, and give a certain character to the group which it did not before possess. The causes are these: the poplars being taller than the other trees, and terminating in a point, serve to carry off the group into the sky, or whatever may be behind it; and their pointed heads form a pleasing contrast to the round heads, and break the too uniform line exhibited in the round-headed group (a). Then their branches rising stiffly upwards, contrast with and render more graceful the pendent ones; and their stems being taller, form an agreeable variety in the lower part of the group.

Of course, there are other trees which would add considerable interest to the group under consideration, particularly those of the fir tribe, and such as are of a light and pendent

nature; but my object has been to consider the lombardy poplar under the least advantageous circumstances, and to show its value and importance in breaking the monotony of most plantations Its combination with other trees, and remarks on them individually, may become the subject of some future paper. I am, dear Sir, Yours, &c.

No. 1. Wellington Street, Waterloo Bridge, Strand.

JOHN THOMPSON.

ART. IV. Observations on an Hypothesis concerning the Effects of Green Vegetable Manure. By ANTHONY TODD THOMSON, M. D. F. L. S., &c. Author of Lectures on Botany.

Dear Sir,

IN perusing the first volume of the Transactions of the Horticultural Society of London, I was particularly struck with an hypothesis advanced by a gentleman, to whose labours in Phytology the world is very largely indebted, Mr. T. A. Knight, in a paper read by him before that society, "on the advantage of employing vegetable matter, as manure, in a fresh state." The hypothesis referred to, assumes as a principle, that plants thrive better on a soil manured with green-vegetable matter, because "many vegetable substances are best calculated to re-assume the organic, living state, when they are least changed and decomposed by putrefaction."

The grounds on which Mr. Knight has raised this hypothesis are two, well-contrived experiments. In the first, the seeds of the Plum vegetated, with uncommon rapidity, in pots nearly filled with the fresh leaves and roots of grasses: in the second, which was a more extended and an admirable comparative experiment, turnips sowed on different portions of the same field, differently manured, grew more vigorously in proportion as the manure approached to the state of fresh-vegetable matter. Thus, the crop was very forward and luxuriant on a portion of the field on which green Fern had been employed as manure; less so on another portion on which fold and stable manure had been used; and least forward on a third portion, the manure of which was completely decayed dung. The inferences drawn from these experiments, are endeavoured to be further supported by Mr. Knight, by an imaginary analogy between the assimilating functions of plants and those of carnivorous animals, "who," he observes," receive more nutriment from the flesh of other animals, when they obtain it most nearly in the state in which it exists as part of a living body."