. Transactions . es which compose it possessgreatly thickened cell walls and narrow cell lumina, while theradial diameter of the cells is usually reduced. (Figs, i, 2, and 3). Inbroad-leaved trees, the autumn wood is composed chiefly of libriformfibres and wood parenchyma, but the boundary line between thetwo zones is not so well defined, nor does the springwood occupyso much space as in conifers. In some, such as Beech and Horn-beam, little difference can be detected with the naked eye in anypart of the wood ring. In both broad-leaved trees and conifers,however, the quality—in a limited sense
. Transactions . es which compose it possessgreatly thickened cell walls and narrow cell lumina, while theradial diameter of the cells is usually reduced. (Figs, i, 2, and 3). Inbroad-leaved trees, the autumn wood is composed chiefly of libriformfibres and wood parenchyma, but the boundary line between thetwo zones is not so well defined, nor does the springwood occupyso much space as in conifers. In some, such as Beech and Horn-beam, little difference can be detected with the naked eye in anypart of the wood ring. In both broad-leaved trees and conifers,however, the quality—in a limited sense—of the timber dependsupon the proportion of autumn wood in the annual rings, the onlydifference being that whereas in the conifers the structure alone ofthe elements in the spring differs from that in the autumn wood,these two zones in broad-leaved trees differ both as regards struc-ture and also in the component elements, although great variationsare found with different species and genera. The exact causes. Fig. I. -Transverse section of Scots Pine wood from outer part of lOO yearold tree x 24. Average breadth of ring -5^ i^i-
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Keywords: ., bookcentury1800, bookdecade188, bookpublisherlondon, bookyear1883
