Inhaltsangabe
This historic book may have numerous typos, missing text or index. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1903. Not illustrated. Excerpt: ... boughs. To guard against this mischance the tree wears a union garment of cork, enveloping roots, trunk, and branches; for cork is useful in the woods, as it is in the medicine chest, just because it is impervious to fluids, vapor, and fumes. The stem of a seedling tree is covered with a delicate green skin of leaf-like texture. This affords but inadequate protection against parching and frost. Something more dependable is soon needed to take its place, and this new want of the baby tree is filled by a well-fitting suit of cork. A like covering is soon given to young branch tips, and it appears as a very fine, transparent, brownish skin. This cork skin, like all other parts of the tree, is made of many cells, but instead of lying somewhat loosely together, as plant cells often do, with a chink here and a space there, these are ranged in rows and joined as accurately as tiles in flooring. There is some brown coloring matter in their walls, but inside they are generally empty of everything save air and a little tannin. So when there are several layers of cork cells, one behind the other, they act as the air-space does in a double-walled house, opposing a barrier to summer heat and also to winter cold. But also it is often a barrier between life and death. Sap cannot get through it, so that if there are any tissues outside it they gradually starve, shrivel, and dry out. Most trees wear their cork as an undervest, beneath the cracking and weather-stained outer bark. Just under the cork suit, at the growing season, there is an investing layer of young cells all busily at work making new cork. During the whole life of the beech its cork manufacture is carried on each spring near the surface of trunk and boughs. But in most trees the seat of this particular industry is...
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