« PreviousContinue »
understand the nature and progress of buds in all plants, except the cryptogamia and water-plants. These I am deeply studying; and I flatter myself it will not be long before I'
shall be able to complete my sketch in this respect.-I shall New practices now endeavour to account for the cause of the succeeding in gardening. of various means lately adopted in gardening, and show the reason that success attends such practices. All that For- Why Forsyth did to old trees, was to take from them the rotten syth's method part, which wholly checked the growth of the albumen, by soaking up the juices, which should have produced it? but the sap once returned to its usual office, forming the new wood, or albumen, gave an increased vigour to the line of life, which, when the rotten part was cut away, had room to shoot afresh, and by a quicker circulation of the sap re newed the vigour of every part of the plant. Scarcely has the year power to run its usual circle, before a tree so reani mated will begin to shoot at the very heart; the little' pith to be found in so old a tree can hardly raise moisture enough for the innumerable buds, which form in every part, on the line of life; beginning at the dilapidated part, and soon communicating to all the rest. It is astonishing what good may be done, by thus now and then paring away a part, that ap pears to be beginning to decay: but then it must be cut with great care, and covered with the plaster ordered by Forsyth, which is excellent; and not left to contract the rot. The The preserva dried stump of a tree, or the remains of a broken limb, tive to the hay in a very few years (by this management) be the source of new shoots, more than equal to those before lost; and though I believe with that philosophic observer Mr. Knight, that there is a term of life and vigour, beyond which a tree cannot pass: yet it is certain, that it is a very ancient time, and that almost all our trees die from careless inattention, and probably at half their proper age.
There is a strange idea universally spread among physio- Sap in a tree logists, arising (I must think) from our ignorance of the in- never atagtérior formation of plants, but universally received as a truth; that as wood grows old, it contracts in form, till all the passages of the fluids are stopped, and it remains in a kind of torpid state, till it dies. This idea appears to me to be so contradicted by all I have seen in nature, by my
compressed by health.
hourly study of the disorders in plants, and by the consider ation of that sort of life which plants possess, that I am very anxious to show the fallacy of it. Wood once reduced to this state (it stands to reason) could never again recover; it could never throw out buds, it could never again be re-, stored to a regular rising of the sap; for the vessels are so small, that, once choked, it would require a miracle indeed
to open them; and yet it is well known, that a tree may be restored to almost pristine vigour, by a little cutting and care: and then, so far from being in a fixed state, every vessel of the wood must be moved out of its place, must bend in one way or other for the exit of the buds, the juices must be so plentiful (the sap in particular) as to form albumen to engender and accompany all those buds. Where then is its Parts between torpidity? It is true, that, the older wood grows, the more, the vessels it is compressed; but it is the middle part between the ves sels, that is reduced. A very simple proof may be given of this, by cutting the oldest piece of wood, that can be found in a living tree, and placing it in the fire: the quantity of, sap, which runs from each separate vessel, bubbling and spouting out as soon as the heat acts, will quickly show how full of sap the oldest vessels are. But this very com-: pression only more strongly proves the health and strength. of the tree; it quickens the circulation of the juices by pressing the bastard pipes against the sap vessels, and thus gives increased vigour to the tree. I will be bound to say, that the passage of the vessels was never suspended in a plant, without causing the gangrene directly, and very soon death. To prove, that I am not too hasty ip this assertion,, I will simply show the general manner of the death of trees, when they die naturally, and without accident. The first appearance of sickness is the hanging down of the branches and leaves: this is followed by a sweetness pervading all the different juices of the plant, attracting every species of insect, which soon cover and spoil the leaves with their filth: then little divisions of the wood (grown weaker than the rest) burst their vessels, and begin a sort of rot, which increases daily: the spiral wires, which attach the leaves to the stem, begin
Death of a tree.
This is so peculiarly the case, that almost all the disorders of trees arise from a stoppage of the circulation in different parts.
to grow brittle, and their cases to crack: the nourishing vessels round them decay, and the first wind, of course, takes off the leaves, and the next circumstance is generally the death of the line of life; which, when once it begins to be affected, soon bursts, turns black and dies: this spreads an increased sweetness over the plant, by the juices of the line; which, though often bitter, are luscious, and tempt the worm. From this time nothing can save the tree, though the bark and rind may still show some green; nay, I have known a fine day burst the leaf-buds, so little has the leaf to do with the plant, but they are soon gone; and the remain der sinks to torpidity and death. I have watched many trees from the first to the last in this way, and taken down their symptoms as they increased, by cutting branches, and thus judging of the progress of the evil; but if at the first appearance of it, care had been taken, the tree had been dug round, and a little dressing thrown with fresh earth; and if the disorder continued, and showed in any particular spot;. had this been cut away, and managed as mentioned above, for lo excite to fresh action is every thing in a plant, and air To excite to and light if possible let to it by cutting down any rubbish that action gives health to a impeded it, many trees might be saved, and much wood re- plute. stored to the country. Light is certainly the most necessary desideratum to plants. It is painful to see how trees will twist their branches in search of it, and perhaps be disap pointed at last. A tree is therefore so far from dying by too much compression, that this is always a sign of health; as the spreading out and growing irregular in the branches is a sign of sickness. But I must dwell on this subject no longer,
I mentioned, that when a bud is protruded, a knot is The breaking formed on the line of life, which is broken, and the two ends of the line of form buds. All that is necessary, therefore to form a bud is, to divide the line of life; this gardeners have learned to do, by cutting a gash in the place they mean to make prolific. They then not only divide the line, but they also separate the wood, which hastens the bud, as it has not to prepare the wood for its exit from the plant. This very much quickens the business; but then there is evident danger in the doing it. In the first place many buds may be destroyed in their
Difference of the flower bud and mixed
way: the finger should therefore be pressed all up the part, to be well assured that there is no branch on the point of shooting; the bud will be feit as soon as the bark and rind have made a socket or bed for its reception, which is done before the bud is half way on its journey: then a plaster should be prepared to cover the gash, without pressing it too close, but taking care to guard it well from the air, lest any should get in and cause a rot, more easily gained than cured. I have often found a bit of bladder, placed under the plaster, a better preservative than any thing else, if per fectly clean, and free from all grease.
I promised at the conclusion of this letter to show the difference of the flower bud, and the leaf and flower bud, which is very trifling. They both come from the same and both in the same manner. arrived at its cradle, the rudiment of
place the line of life the mixed bud, when the flower stops while the leaf is weaving. The first has also some few leaves to complete, and many scales. The female or pistil of both was a rude mass containing the seeds, but now begins to take its proper form; while the males, all joined together, and proceeding from the wood, are completely fashiqued. The scales in the mean time are growing to cover it thoroughly, and most buds have a quantity of their juices (that is the blood of the plant) lying between the several covers. as a sort of resin, to protect it from the air and cold, of which it is now very susceptible. In the mixed bud, the leaves always are finished at the top, before the flower, even where the flower comes out first, to prevent Various juices the matter of the leaf, or mixing with the juices of the flower; a care which is peculiarly evinced throughout the whole formation of plants; and which it is wonderful to me physio logists have not observed, since their whole make is founded on this principle-the keeping all their juices perfectly se parate. For this reason all the vegetable world is formed cylinder within cylinder; and, when there are holes, they are so contrived, that nothing but air can enter them. I shall soon exemplify this by delineations of the passage between the stem and the peduncle; which plainly show how strongly this principle is maintained in every instance, and how little therefore we can judge of the effect of the
of the tree always keep separate.
juices when we mix them all together. As to the leaf bud, I have in my last letter said, it is begun and finished in the bark. It is indeed a history in itself, and one of the most wonderful I know. There is so much pressing, rolling, and weaving, that I have constantly viewed it with fresh astonishment; for after being woven with all its parts loose and Formations of open, and all the ends hanging to it, like a piece of cloth the leaf bud. fresh from the loom, it is folded anew, rolled in a particular manner, and laid in a liquid; then unrolled, and again folded in another manner, and pressed in the bud; and this is repeated several times, till by degrees losing all its ends, it is prepared for making the edges, which is the most curious part of all. I have already detailed this in my first letter, and shall not therefore repeat it, but only say, that the leaf buds of those plants, which have no stem, are formed within the bosom of the other leaves, joined to one end of the cu ticle, not in the root. I have much to say on this subject, but it must be in another letter, and one which is restrained. to leaves alone.
vessels for the
I must now say a few words on a subject I have long de- Whether there ferred touching upon, but which I have not the less studied; are returning indeed I hardly know one that has lately engrossed so much sap or not? of my thoughts; I mean, "whether there is, or is not, a circulation of sap through plants." After the most mature inquiry, the most exact research, I cannot discover the slightest reason for believing, that it takes place even in trees; on the contrary, the most potent arguments, drawn from the very nature of the vegetable tribe, militate against it. That there is a regular passage upwards for the rise of the sap, no one denies; but returning vessels from the head of the plant to the root 1 must think a fallacy; arising from that unfortunate comparison established between the animal and vegetable world, which was well enough in the first birth of both, but has been carried in my opinion to a false and blamable extent. Can any thing be more unlike animal life, than the shooting of the buds? This will, I think, more plainly appear, in drawing a comparison between the functions of both -in an animal constant motion is necessary to circulate the Sap too much blood; its juices, formed in the body itself, from the dif- exhausted by ferent secretions I believe, (but I do not understand ana- mations.
its various for