usual way, and may also be used for

rhubarb,

seacale,

winter potatoes, &c.

The peach and 9

vine wall (fig. 75.)

is proposed to in

close a plot of
ground thirty or
forty feet long, and
of any convenient
width. A fire-place
(a) is sunk in the re
soil at one end, and
two flues (b, c) pro-
ceed from it, the
tops of which (d)
are level with the
ground's surface.
These flues meet
at the opposite end
(e), and may be
carried up either
in brick-work or in
earthen pipes, so as
to meet in a chim-
ney-top, concealed
in the pediment (f),
over the centre of
the door-way to the
inclosed space. If
these flues run east
and west, or south-
west and north-
east, then one of
them may be cover-
ed with boards for
growing peaches on
both sides, planting
the trees in the in- Mow
side (h), and train-

ing them up one

side and down the other; and the other flue may be

covered with boards, and a wire trellis on one side (i), for vines, and glass frames on the other side (k), to admit the light, and retain the heated air from the flue. The vines should be planted in the inclosed border, which should not be very deep, and might be paved at bottom and well drained, so as to limit the supply of nourishment, and check the overexuberance of growth in both peaches and vines. The roots of the vines may be kept apart from those of the peaches by an underground division of slates, or a brick-on-edge wall; indeed, it would be an advantage to limit the roots of each particular vine and tree in the same way. As there would be some difficulty in glazing the round ends, they may be boarded and covered with peaches, leaving only the straight part for vines.

When the peach-trees are in blossom, they may be protected by a moveable coping, and by a canvass or gauze covering. Standard peaches may be planted against the glass (k), with stems sufficiently long to reach the height of the structure, and their heads may be trained down the opposite side ().

This structure should be rounded at the top, for the more easily training the trees over it; and it should be well painted or coated over with gas tar or pitch every two or three years, to insure durability, and destroy insects. If each side of the structure be six feet high, both sides will be equal to a wall of twelve feet; and I think the mode of heating will be found superior to that adopted in the common mode of constructing hot-walls. Pots of strawberries might be forced along with the vines, and steam might be produced by pouring water into the trough formed on the top of the flue (d). Dampers might be introduced at the place where the flues divide (m), so as to throw the heat wholly, or more or less, to one side, at pleasure. A walk (n) might go round the piece of ground inclosed; and this ground might be slightly cropped; but it will be better neither to stir it deep, nor to grow any thing on it, but merely to keep it clear of weeds. Care also must be taken not to disturb the partition between the roots (o); and if, as I would recommend, each separate tree be partitioned off, the ground should neither be dug nor cropped, but manured on the surface, and slightly pricked up with a fork two or three times a year.

I think a structure of this kind would have a good effect on each side of the main walk in a garden, as a substitute for an espalier rail. Both furnace and chimney-top might be connected with the outer wall of the garden, so as not to be

offensive, or to show that any flue or fire was connected with I remain, Sir, &c.

the structure.

Wollaton Gardens, Dec. 1826.

JOHN HAYTHORN.

ART. XII. Experiments on the Growth of the Foliage of Bulbiferous Plants. By ANTHONY TODD THOMSON, M.D. F.L.S. &c.

Dear Sir,

ONE advantage of the Gardener's Magazine, highly important to the labouring gardener, is the opportunity which it affords of communicating to him facts connected with vegetable physiology, which his time and his opportunities of obtaining information, prevent him from acquiring through books; but which, if they were known to him, he might prosecute with advantage, without any interruption to his ordinary occupations. The following observations upon the growth of the foliage of bulbiferous plants, I send to you, at this time, because this class of plants is, now, in such a state that any gardener may verify their accuracy.

In my published Lectures on Botany, I have pointed out the impropriety of regarding bulbs as roots; and have there stated, that they are merely appendages of roots, and sometimes of stems. From the manner in which a bulb vegetates, it may be correctly regarded, also, as the centre of the plant which is produced from it. The leaves rise, and are perfected at the apex, the increments of growth being added at the base, or next to the bulb; while, in the roots or radicles, the additions are made at the points, as in all other plants, a fact which was first noticed by Du Hamel. Thus, if a thread be passed through the radicle of a Narcíssus, for example, it will remain at the same distance from the bottom of the bulb, although the radicle elongate to twenty times its original length: but, if a thread be passed, in the same manner, through the leaf of the plant, it is carried upwards as the leaf elongates. To determine the manner in which the increments of growth are deposited in the leaf, the following experiment was made upon a Narcissus growing in a water glass.

On the 14th of February, 1823, a silk thread was passed through one of the leaves of a Narcíssus, one inch from its apex; another thread was also passed four inches below the

former. The portion of the leaf beneath the last thread and the bulb was two inches. The growth of the plant produced the following changes in the length of each of the abovementioned divisions.

From this experiment it appears that, in eight days, the leaf had increased nothing within an inch of the point; that it had increased one third of an inch only within six inches of the point; and that, between this point and the bulb, the increase was three inches and half an inch; demonstrating that the whole of the increments of growth had been deposited at the base of the leaf, whilst the apex remained unchanged and was carried upwards. It was still, however, necessary to ascertain, whether the apex of the leaf possessed any influence in affecting the growth of the base? and whether the sap, which produced the increase, was first raised to the point of the leaf? To answer these queries, I made the following experiment.

I took a Jonquil which, on the 20th of March, had four leaves, each eight inches long. I cut off one leaf, a, at the height of two inches from its base; another, b, at four inches from its base; a third, c, at six inches from its base; and left the fourth entire. Through the middle of the remaining portion of b, that is, two inches above its base, I passed a silk thread; through c I passed, also, two silk threads, one at two inches from its base, and the other two inches above the former, so as to divide the portion of the leaf into three equal divisions; and in the same manner divided d, the entire leaf, into four equal divisions, one of which necessarily constituted two inches of apex. The result of the growth of the leaves, at the end of three weeks, was the following:a had elongated half an inch only, and had become greener at the base.

b had elongated three-fourths of an inch, and was, also, greener at the base.

c had elongated two inches and a half, and was scarcely altered in colour at the base.

d had elongated three inches and three fourths of an inch, and remained natural, or unaltered in respect of colour at the base.

The inference which I draw from this experiment is, that the sap must be raised to the apex of the leaf, in order to undergo that change which is necessary to render it, on descending, fit to be assimilated into the substance of the bulb; and that it is from this altered sap, that the increase to the leaves is derived: or, in other words, that the apex of the leaf in bulbiferous plants performs the same function as the entire leaf in trees and shrubs.

I remain, Dear Sir, yours faithfully,
ANTHONY TODD THOMSON.

3. Hinde Street, Manchester Square,

March, 12. 1827.

ART. XIII. On the Culture of Orchideous Plants. By A. X. Sir,

THE native orchidea will thrive tolerably well under the following treatment: Choose a spot on a north border, or north side of a hedge, which is sheltered from the sun in the middle of the day, and as much protected from cutting frost winds in spring as possible. Take out the soil to the depth of twelve inches; lay three inches of brick-bats at the bottom of the excavation; cover them with thin turf, and fill up the remaining space with a compost of one half melon loam, one fourth of peat, and one fourth of sand. Plant the roots about three inches deep, surrounding the bulb with an inch of sand, which will prevent them from perishing in wet weather, by absorbing the moisture during the time they are in a dormant state. Put a light covering of furze or fern over the bed in March and April to shelter them from cutting frost winds. At this season they frequently get cut off even in their native places of growth by the severity of the weather. The species that will succeed treated in this way are, Habenária bifólia; O'rchis Mório, máscula, latifólia, maculáta; Gymnadenia conópsea; Hermínium Monórchis; Listéra ováta; Epipactis latifólia, and palustris.

The following species are more tender, and, to ensure their preservation for years, they ought to be potted in the same compost as directed for the bed above described, with plenty