. Studies in fossil botany . Paleobotany. SPHENOPHYLLEAE 93 39. This peculiar structure of the wood is found both in the English (Figs. 38 and 39) and in the French forms (Fig. 36, D), but is not common to the whole genus, as we shall see presently. The elements of the wood are arranged with the greatest regularity (Fig. 38). There is a marked difference in size between the second- ary elements found opposite the sides of the primary wood, and those corresponding to its angles ; the former are much the larger (see Fig. 38). In the small-celled wood oppo- site the angles there is an approach to
. Studies in fossil botany . Paleobotany. SPHENOPHYLLEAE 93 39. This peculiar structure of the wood is found both in the English (Figs. 38 and 39) and in the French forms (Fig. 36, D), but is not common to the whole genus, as we shall see presently. The elements of the wood are arranged with the greatest regularity (Fig. 38). There is a marked difference in size between the second- ary elements found opposite the sides of the primary wood, and those corresponding to its angles ; the former are much the larger (see Fig. 38). In the small-celled wood oppo- site the angles there is an approach to the formation of continuous rays. In the best - preserved specimens we find, immedi- ately beyond the wood, the delicate tabular cells of the cambium itself, sometimes Fig. mOSt distinctly Shown, and Radial section through pait of . secondary wood, showing pitted beyond thlS We COme tO a tracheides and parenchyma (?•). X50. r 11 J _„JJ„1K, P/u/. Trans., W. and S. Will. Coll. zone of thin-walled radially- 884 arranged tissue, which can only be interpreted as the phloem (see Fig. 38).1 Beyond this again, in older stems, lies a wide band of firmer tissue, also radially arranged, which we must regard as internal periderm (Fig. 38). If we examine a comparatively young stem of Sphenopkyllum, we find, in many cases, a very distinct beginning of periderm- 1 For more complete illustrations of the various tissues, see Williamson and Scott, Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Scott, Dukinfield Henry, 1854-1934. London, A. and C. Black
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