Page:An introduction to physiological and systematical botany (1st edition).djvu/60

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OF THE WOOD.

the bark is removed, we come to the substance of the wood, which makes the principal bulk of the trunk or branch of a tree or shrub. When cut across, it is found to consist of numerous concentric layers, very distinct in the Fir, and other European trees in general. Each of these circular layers is externally most hard and solid. They differ however among themselves in this respect, as well as in their breadth on the whole. It often happens that all the layers are broadest towards one side of the tree, so that their common centre is thrown very much out of the actual centre of the trunk.

The wood owes its strength and tenacity to innumerable woody fibres, and consists