. Wood; a manual of the natural history and industrial applications of the timbers of commerce. Wood; Timber. BUNDLES AND PITH-EAYS 9 other cases, as in the Oak, the cells of the pith have their walls thickened, and turn from white to brown; but even then its rela- tively minute width makes it difficult to detect in a stem several years of age. The procamUum strands extend, from the rudiments of leaves near its apex, right through the stem into tiie root. They get their name from a Latin word, cambio, to grow, being in a merely transi- tory or embryonic condition. In Monocotyledons the whole o
. Wood; a manual of the natural history and industrial applications of the timbers of commerce. Wood; Timber. BUNDLES AND PITH-EAYS 9 other cases, as in the Oak, the cells of the pith have their walls thickened, and turn from white to brown; but even then its rela- tively minute width makes it difficult to detect in a stem several years of age. The procamUum strands extend, from the rudiments of leaves near its apex, right through the stem into tiie root. They get their name from a Latin word, cambio, to grow, being in a merely transi- tory or embryonic condition. In Monocotyledons the whole of their tissue passes into the condition of wood and bast; so that the bundle, as the strand in its permanent form is termed, being incapable of any further growth in diameter, is said to be closed. It is because it gives rise to a bundle (Greek, desmos, a bond) that B. Fig. 5.—Three stages in the early development of an exogenous stem, m, pith; r, cortex; h, primary xylem: fl", secondary xylem ; b, primary phloem; B, secondary phloem ; c, cambium; ms, pith-ray. the procambium is termed desmogen. In those trees, however, with which we are concerned, viz. Gymnosperms and Dicotyledons, whilst the inner portion of each strand becomes wood or ocylem (Qreek, xylon, wood) and the outer part bast or phloem (Greek, phloios, bark), a band between these two parts remains embryonic. This layer is called the cambium, or more precisely, for a reason we shall see presently, the fascicular cambium, the cambium, that is, within the bundle. Such a bundle, poss6ssing such a cambium- layer, is termed an open one. Between the bundles, connecting the pith in the centre with the cortex on the outside of the ring of bundles, are parts of the original or ground-tissue of the stem, which are known as primary medullary rays or pith-rays (Fig. 5). In Dicotyledons they are. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - c
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