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80 PATTERSON v. M'CAUSLAND,
our country, exhibit any such indications of the formation of suc-
cessive concentrical layers, as are to be found in a stem of the
oak, pine, &c. (w.)
The conspicuous formation of successive layers of wood is,
however, not only confined to trees of a particular class, but even
among them the formation of such layers differs materially, accord-
ing to their respective species, ages, and situation, when growing
in their several appropriate climates. And yet a tree of one spe-
cies engrafted upon the stock of another of the same species, will
grow vigorously, producing fruit of a different kind, and wood of
a very dissimilar appearance from that on which it grows. It is
remarkable, that the branches of the resinous trees consist almost
wholly of wood, of which the organization is even more perfect
than in the body of the tree; the reverse is observed in trees with
deciduous leaves, (x) There are six times more concentrical cir-
cles in a given space of the yellow pine, (pinus mitis,) than there
are in the pitch pine, (pinus regida,} or loblolly pine, (pinus
taeda.) (y) The wood of the black oak, (quercus tinctoria,) is
coarse grained with empty pores; (z) that of the red oak, (quercus
rubra,) is also coarse grained, with pores large enough for the
passage of a hair, (a) The wood of the sweet gum, (liquidamber
styraciflua^) when sawn into boards, is observed to be transversely
marked at considerable distances, with blackish belts; (b) that of
the black gum, (nyssa sylvatica,) and its genus, has its fibres inter-
woven and collected in bundles. It is difficult to split the wood,
which in the arrangement of its tubes and woody fibres strikingly
resembles that of a tree of the endogenous class, (e) The inter-
nal structure of the sugar maple, (acer saccharinum,) seems to
undergo several changes in the course of its life. As the growing
tree rises to maturity the grain of its wood becomes more undulated
or curled; and, at an advanced age, by an inflexion of its fibres, from
the circumference toward the centre, there are produced a kind of
spots, which, when the wood is polished, resemble bird's eyes, (d)
So, too, as age advances, the wood of the oak likewise undergoes
some sensible changes; for, it has been said by a person in Eng-
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(w) Rees' Cyclo, v. Monocotyledon, Palmae, and Wood; Roget Anim. and
Veget Physi. pt. 1, c. 1, s. 2.—(x) 2 Mich. Am. Sylva, 274.—(y) 2 Mich. Am.
Sylva, 254, 268,—(z) 1 Mich. Am. Sylva, 92.—(a) 1 Mich. Am. Sylva, 104.—
(d) 1 Mich. Am. Sylva, 318.-(c) 2 Mich. Am. Sylva, 166.—(d) 1 Mich. Am,
Sylva, 227.
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