will bring portions of the epidermis, or outer layer of the bark, adhering to them. It is evident that on a smooth bark this direction must be the most effectual in fixing them to the part, but if the latter be rough and chinky, then you will observe that the claws in general run perpendicularly into the fissures, and do not spread out sideways, which in this case would not be so effectual. When the ivy is old enough to have a trunk, then the claws shoot out from the latter, and its larger branches on all sides, so as to render it rough and as if clothed in bristles; but we never see this in the young state.

Through the medium of these claws the ivy ascends to a great height; it will mount the highest castle or tower, and wave triumphant on its summit; and yet, though it climbs the trunks of very high trees, we do not find that it ascends far upon the branches. If it did so it would injure the tree very materially, or destroy it, by choking its leaves. Have you ever remarked how the shape of the ivy-leaf varies according to its situation? It differs greatly according to circumstances, and I apprehend that the variations are connected with, a very curious and important part of the economy of the plant. The leaf of the young

sometimes like (6), and while the plant is climbing, it is almost invariably of this form. But if a branch project from the stem, and hang out free from the tree or wall, you will find that the leaves of such branch are ovate or lanceolate (fig. 7.), and also, that on the branch itself there is no appearance of claws.

Since I commenced the present letter, I have paid considerable attention to this plant, and on examining it on the wall of the Cave-hil deer-park, which is about nine feet high, I observed the generally well known fact, that the leaves were all pentangular, until it had mounted very near the top of the wall, and then numbers of them had become exactly heart-shaped, while all those on the branches that had surmounted the wall were ovate or lance-shaped I had long before remarked what I consider a curious circumstance, which is, that although ivy produces its berries in very great abundance, and each berry contains five seeds, yet one single plant seems to usurp the complete possession of a large portion of wall, to the exclusion of any other plant of the same kind growing in its vicinity. The most remarkable examples of this, with which I am acquainted, occur on that noble ruin the castle of Rothesay in Bute. The following sketch of part of the court-yard of that place will illustrate my meaning: (a) is a very large ivy tree spreading from one trunk (b), along a great extent of wall, and though it must, I should suppose, produce many thousand berries every year, yet there is no appearance of an ivy plant growing under all the space (cd). This is very remarkable at our

deer-park, where often one plant is lord of the wall for a great extent, without any appearance of others of the same species presuming to spring up near it.

Fig. 8.

The trees in the above sketch which rise above the wall to a considerable height are ashes, which have taken root there, but it is not the habit of the ivy to shoot far above the summit of the object up which it has clambered. When an ivy trunk has got fair possession of a wall, its branches diverge from it somewhat in manner of the spokes of a fan, and when they have reached the top of the wall they creep

along it laterally, forming innumerable twistings and overlappings, by which the whole are bound together in the strongest manner, and the branches which rise up and bear the flowers and fruit, are, in general, rather lateral ramifications than the continuations of the stem. They do not overtop the wall more than two or three feet, for the économy of the plant seems to be altered whenever it has got on so far as to stand no longer in need of its claws. Its whole powers then seem to bear on the ultimate object, the production of seeds, and when it is arrived at the top of the wall a higher elevation is unnecessary. It is the same circumstance, I believe, that limits the growth of the plant, in a great measure, to the trunk and part of the larger branches of the tree. When it has got so high, the formation of claws and tendency to climb cease, and the branches produce flowers succeeded by berries. In the adhesion of ivy to rocks and walls, the frequent overlapping of its branches serves most materially to strengthen its hold, and we observe innumerable young branches not climbing up in the direction of the parent trunks, but crossing and twining over them in all possible ways, transversely and oblique, and tying them down as with strings or cords to the surface on which