occupies the centre of the latter from one extreme to the other. It is a spongy substance called cellular tissue, because it consists of little bags or cells. It constitutes the chief of all young shoots, and in them has always a greenish tinge, from these little cells being filled with a fluid of that colour; but as the shoots advance in age this fluid gradually disappears, and ultimately the pith becomes white. It is one of the simplest forms of vegetable tissue, and the most rapid in its development; it is, therefore, well adapted to the end for which it appears to be chiefly designed, viz., to act as a reservoir of nourishment upon which the tender leaves and vessels of immature shoots may feed, till they can obtain a more perfect means of supply.

Beneath the bark, and only separated from the pith by the medullary sheath, (an exceedingly delicate membrane, consisting of spiral vessels containing air, and forming a very thin layer round the pith,) we find the layers of wood, each of which is the growth of one year, consequently their number indicates the age of the tree. This only holds good, however, in trees of temperate and extreme northern and southern latitudes, where the powers of vegetation are for a time suspended; because in the more congenial climate of the tropics the trees experience no such check upon their vital energies, and, consequently, their annual growth is less distinctly marked, the wood of one year seeming to pass imperceptibly into that of another. In glancing at the cross section of the stem of the Hazel above cited, it will be seen that its annual zones are radiated by fine lines passing from the centre to the circumference. These lines are called medullary rays. They consist of thin vertical plates, of the same kind of tissue as the pith, of which, in fact, they are a lateral extension, establishing a connexion between the interior of the stem and the bark. The inner and outer sides of each annual layer of wood differ somewhat in their character. That side lying nearest the pith is composed chiefly of sap-vessels or ducts, organized in the early part of the summer, from a viscid fluid called cambium, which is secreted, in the spring, between the bark and the wood. Through these vessels the sap, taken up by the roots, ascends to the leaves. That side of the woody layer lying nearest the bark is of a more compact texture, being composed of woody fibre, elaborated and sent down by the leaves much later in the summer. It is a very firm tissue, and gives to the stem great mechanical strength.

The bark is the external covering of the stem, and has justly been termed the universal leaf of a vegetable, because in it the proper juice of a plant receives its final elaboration. It is provided with a system of branching vessels analogous to those which are seen on the under surface of a leaf. Through these vessels the elaborated sap is conveyed, and thence, by means of the medullary rays, to every part of the system. The distribution of the proper juices of a plant furnish a fine display of Divine intelligence. Some of it is expended in the production of new layers of wood, some in the production of new branches; the leaves require a definite quantity, so also do the flowers and fruits; a portion is also sent downward to the root, and

appropriated to its elongation and to the development of additional fibres, and better to enable the stem to support the ever-increasing weight above, a quantity is deposited in the cells and vessels about its centre; and, lastly, it is secreted in great profusion by the new wood and bark to form cambium, and to nourish, in the spring, the newlyopening buds, until the roots are called into activity.

The leaves, as has been before observed, are flat expansions of the bark. They are usually supported upon foot-stalks, and consist of a principal vein or mid-rib, whose ramifications form a sort of net-work, the interspaces of which are filled with cellular tissue. And then, better to protect their juices from excessive evaporation, the whole is covered with a thin skin or cuticle, studded with innumerable minute orifices (stomata), which open and close in conformity to the vicissitudes of the climate, and serve to regulate the amount of exhalation, &c. They are to a plant what the stomach is to an animal; for as the food taken into the stomach of the latter undergoes a series of chemical actions, its nutritive chyle being separated and taken up by the lacteal vessels, and thence, by means of the thoracic duct, to the blood-vessels, wherein it circulates and ministers to the growth and sustenance of the whole body; so the food conveyed into the leaves of a plant is also subjected to chemical action. By the agency of light its water is decomposed, and the superfluous portion (in some plants about four-fifths of the whole quantity introduced) passed off by exhalation; and the remainder, after receiving the necessary constituents from the atmosphere, is returned in the shape of proper juice, through the veins of the leaves to those of the bark, and thence by the medullary rays to every part of the structure.

BRITISH PLANTS:

WITH OBSERVATIONS ON THEIR CULTURE.

BY W. JOHNSTONE, ESQ., BALLYKILBEG HOouse.

PERHAPS in these few remarks there may be nothing very new; and we are convinced that the flowers selected are not the only ones deserving of attention, if, indeed, many others are not much more so; but they are simply selected because with them we have some small acquaintance, and with a hope that, by making a commencement, deficient of merit though it be, to induce others, more capable and better qualified, to come forward with their pens in behalf of the very lovely floral beauties of this our own dear sea-girt isle.

. I am convinced that many rich gems might be added to the garden parterres from our meads, marshes, and mountains, which are heedlessly pulled and cast away by some rustic wanderer, or bloom unnoticed in the habitations of those birds of the waste, the bittern and ptarmigan.

If many a native flower that now springs up, blooms, and withers away, unheeded and uncared for, were transferred to the soil of the garden, where art, with her fostering hand, would be ready to assist

nature, we should have plants which might fairly challenge comparison with the showy beauties of warmer climes. Any one knows what has been done with the Primrose, the Daisy, the Pansy, and the Violet; and if some patriotic lover of nature would transfer some of the botanical ornaments of our hills and dales to his garden beds, and devote to them a moderate share of time and attention, I am confident that very much might be done, and that the devotion of such time would be repaid in the production of such lovely novelties as the imagination has not yet pictured, and would confer a very great benefit on the horticultural world in general. The object would not be at all difficult of attainment, and I hope many fair ladies, with their tender hands, may be induced thus to effect the removal of some of our own sweet flowers from their wild homes beside the mountain stream and woodland glade.

Cypripedium calceolus.-This lovely plant is certainly the queen of British Orchids, and it is to be lamented it is so rare. It is generally said to be an "inhabitant of woods in the north of England," but we question if plants of it could be procured at all in the wild state, or in their native habitat. So very rare is it, that we are informed by a gentleman who has a large clump in his possession, that C. parviflorum has been frequently shown for it at the Edinburgh exhibitions. Now, independently of the superior size of C. calceolus, which is nearly double that of C. parviflorum, the calyx of the former is yellowish-green, while that of the latter is greenish-brown-in mature specimens brown with green tips. Cypripedium calceolus flowers about the middle of May. The clump already mentioned is growing in sandy peat, and has not been moved for twenty years.

Melittis melisophyllum.-In general appearance this plant is not unlike the Sages. Though it has nothing very remarkable about it, yet it is well worthy of a place in the flower-garden. During June and July its pretty pink and white blossoms form no mean object of attraction, though, on its leaves being handled, the same unpleasant perfume common to the dea or dead-nettle (Lamium purpureum), may be perceived. It should be grown in good loam, and propagated by dividing the roots, by cuttings struck in heat, and, perhaps, by seeds, but this I have not yet ascertained.

Pinguicula grandiflora.—Few of our flowering plants, or, indeed, those of most other countries, surpass in simple loveliness the present subject of our remarks. Hooker says, "This plant, apparently as rare on the Continent as in Britain, and perfectly distinct from P. vulgaris, may be easily cultivated for a number of years. The old leaves die away in winter, and buds, or hybernacula, are formed, which expand into perfect individuals in spring. Few plants exhibit a more beautiful appearance early in the year than a cluster of Pinguicula grandiflora, blossoming under the shelter of a common frame." It may be raised from seed. I have found P. vulgaris growing in rotten blocks of wood, kept always moist by a mountain rivulet. P. lusitanica, with its pretty pale lilac blossoms, is found on the Mourne Mountains. If a cross could be effected between this and grandiflora, as it is highly probable it might, so as to have the size of grandiflora

with the colour of lusitanica, it would be a lovely addition to this tribe.

Tulipa Sylvestris.-This, our native type of an extensive genus, is, as its name implies, a native of the woodlands. I believe that, in common with Tulipa Clusiana, it changes its position by forming bulbs at the extremity of long fibrous roots, descending from the old root. It flowers a month earlier than the garden sort, and is considerably smaller, of a pale yellow or canary colour, having the exterior of the three outside petals, or calyx, greenish. It is a delicate looking plant, and is particularly interesting as belonging to the British flora.

I have transferred Orchis latifolia from a ditch to a bed in my garden, which is considerably lower than the surrounding ones, and it has succeeded admirably. All the Orchids are worth trying. Saxifraga oppositifolia, with its lovely little pinkish-lilac flowers, produced in March, is also a very desirable plant for a rockery or flower-bed. Many others might be enumerated; however, I will not at present trespass further on the pages of the CABINET, but hope some one will favour me, and its numerous other readers, with articles on this subject, and that my humble efforts may be the means of inducing some competent person to take it in hand, when I trust in a brief space of time to see our too long neglected native plants occupying their proper position in every garden throughout the land.

ATMOSPHERICAL CHANGES INDICATED BY PLANTS.
BY ANAEL.

"Closed is the pink-ey'd Pimpernel,
"Twill surely rain; I see with sorrow,

Our jaunt must be put off to-morrow."-Jenner.

AN attentive observer of nature gathers many a useful lesson and many a practical observation from objects, that, to the vain or ordinary observer, are allowed to occur unheeded; and whilst our scientific men are exploring the solar system, to unravel the mystery of the many aërial phenomena, and predict the changes that are daily and hourly occurring, it is pleasing to remind the more modest lover of nature, that beneath his feet, and surrounding him on every side, are objects replete with information and interest, affording many singularly beautiful and curious facts connected with the changes of the weather. The vegetable kingdom was the calendar in which the great Linnæus examined as a directory of the seasons, and which he exhorted his countrymen to observe, with all care and diligence, as the surest guide by which to direct their operations in the field and garden. Why," says Pliny, (Nat. Hist., b. xxiii., ch. 25,) "does the husbandman look up to the stars, of which he is ignorant, whilst every hedge and tree point out the season by the fall of their leaves?" A circumstance indicating the temperature of the air in every climate, showing whether the season be early or late, and constituting an uni

versal rule for the whole world. The minor changes in the atmosphere, with which our variable climate makes us so familiar, are so accurately foretold by many plants, that the attention devoted to its consideration will be amply repaid by the discovery of such interesting properties.

"Flowers shrinking from the chilly night

Droop and shut up, but with fair morning's touch
Rise on their stems all open and upright."-Montague.

The sensitive indications developed by the common Pimpernel (Anagallis arvensis) are so well known, that it has been entitled "The Poor Man's Weather-glass." It is

"Of humble growth, though brighter dyes,

But not by rural swains less prized,

The trailing stems allure

Of Pimpernel; whose brilliant flower
Closes against the approaching shower,
Warning the swain to sheltering bower,

From humid air secure."-Moral of Flowers.

Its bright tiny flowers close some hours before the occurrence of rain, and "go to sleep," or close up soon after noon, expanding again at seven in the morning.

The Germander Speedwell (Veronica Chamædrys), so universal a favourite in every hedge-row, closes its lovely blue flowers on the approach of rain, and as surely opens them again when the storm is overpast.

"Not for thy azure tint, though bright,

Nor form so elegantly light,

I single thee, thou lovely flower,
From others of the sylvan bower,-
Thy name alone is like a spell,

And whispers love, in "Speed-thee-Well.'"

It is observed that if the Siberian Sowthistle shuts at night, there will generally ensue fine weather on the next day; and if it opens, cloudy and rainy. If the single African Marygold remain shut after seven A.M., rain may be expected. If the Trefoil contract its leaves during the day, heavy rain generally ensues; and Lord Bacon has observed, that its stalk is more erect against rain.

The common Chickweed (Stellaria media), in fine weather, supports its flowers upright, and open from nine in the morning until noon; but if it rains they remain closed, after rain they become pendant. This plant, it is said, affords a remarkable instance of the sleep of plants, for every night the leaves approach in pairs, including within their upper surfaces the tender rudiments of the new shoots; and the uppermost pair but one at the end of the stalk is furnished with longer leaf-stalks than the others, so that they can close upon the terminating pair and protect the end of the branch."

The Purple Sandwort (Arenaria rubra) is another example of a true prophet prior to a coming shower. The flowers, a beautiful rosy-purple, expand themselves only when the sun shines, and close again when the shades of evening draw in, or before a coming

shower.