. Fossil plants : for students of botany and geology . Paleobotany. XVJ LEPIDODENUHON 147 Some of the sections in the Binney Collection (Sedgwick Museum, Cambridge) show early stages in the production of secondary xylem : in the section represented in fig. 167 the secretory zone is succeeded on its inner face by a zone of radially elongated cells, vi, which are clearly in a meristematic condition. The same section shows also the more radially extended form of the xylem of a leaf-trace with its internal protoxylem, px, in. Fio. 167. Lepidod^ndron fuligi'nosum. (Binney Collection, Cambridge.) co
. Fossil plants : for students of botany and geology . Paleobotany. XVJ LEPIDODENUHON 147 Some of the sections in the Binney Collection (Sedgwick Museum, Cambridge) show early stages in the production of secondary xylem : in the section represented in fig. 167 the secretory zone is succeeded on its inner face by a zone of radially elongated cells, vi, which are clearly in a meristematic condition. The same section shows also the more radially extended form of the xylem of a leaf-trace with its internal protoxylem, px, in. Fio. 167. Lepidod^ndron fuligi'nosum. (Binney Collection, Cambridge.) contrast to the tangentially elongated form which is assumed during its passage through the cortex (cf figs. 165, 166). Some sections of Lepidodendron fuliginosum in the Man- chester University Collection are of special interest from the point of view of the method of secondary thickening. In the section reproduced in fig. 168, B, the meristematic zone is seen to consist in part of radially elongated elements, vi, with parallel cross-walls evidently of recent origin. The same tissue is shown also in fig. 168, C, a, D, a, and in fig. 169, A, a. 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 Seward, A. C. (Albert Charles), 1863-1941. Cambridge : University Press
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