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that they do not receive their increment in the above manner, requires no experiment to determine; for every body knows that the trees acquire their increment in that season of the year when the periligneum is separated from the wood by the sap. Besides, nothing can be more evident, than that the wood is possessed of sap vessels, or tubes. This can be shown by a very simple experiment: take a piece of a branch, or the like, bark it clean, and put one end into the fire, the tubes or sap vessels being contracted at that end, and the sap rarified by the heat, will be seen to pass off at the other end in the form of steam, or fluid, according to the density of the wood. And there are some, as the cane, which have these tubes so large, that water will readily pass through them. So that, all that their
experiments could determine was, that the bark is necessary to the life and growth of
the tree. There can be no doubt, however, that the tree receives its increment chiefly from the juices circulating between the wood and periligneum; for we observe that a new ting or stratum of wood is added
every year to the circumference of the old
wood: how this is done, is more difficult to
understand; but we know that solids are formed from water and the finest fluids, by a deposition of minute particles, as in petrifaction and ossification, and it is highly probable that the wood is formed in the same
manner, the old wood serving as a nucleus.
I had observed the bark crack and rend in a thousand places, which I could not conceive to be any thing but an effort of
mature to throw off an incumbrance.
I observed that where she had succeeded, there was a fresh, healthy bark below, and the tree or branch healthy: but where she had failed, the outer bark stuck into the inner like a dry hardened scab in the animal body, till by its pressure * had stopt the circulation, destroyed the inmost bark, and materially injured the health of the tree or branch; and where it went all round, killed it entirely. I had frequently observed a very small portion of the inmost bark, alone, preserve a tree or large branch alive and healthy. I observed that the transverse bark was always, sooner or later, de
stroyed by nature, and never again replaced.
I had that universal law of nature, that man is to live by industry, “By the sweat of thy brow shalt thou earn thy food,” and
I did not conceive that we were to have
killed by the cold of winter, “starved to death.” Seeing they survived this, they were all to be burnt up with the heat of summer. Finding they withstood this also, they were all to die in three years of a lingering illness. The third year is now arrived, and they are neither dead nor sick, but more healthy than ever, and promised
a good crop, which I have no doubt they
would have performed as they had done the two last years bygone, had it not been for the extreme severity of the weather, in the time of blossom and setting. And several trees of great age, with which every means proposed by professional men...had been used, but never bore fruit, have, since peeled, produced very good crops. In corroboration of what I here state from my own knowledge, I beg leave to insert a paragraph from a letter I received from a respectable gentleman in the neighbourhood of Glas