. Fossil plants : for students of botany and geology . Paleobotany. X] ARTHROPITYS. 313 result of active growth, and not merely the expression of the tangential stretching of the stem consequent on secondary thickening. A glance at the complete transverse section of the stem,— of which a small portion is shown in fig. 74 A,—suggests the existence of annual rings in the wood, but this appearance of rings is merely the result of compression. The secondary wood of a Calamite does not exhibit any regular zones of growth comparable with the annual rings of our forest Fig. 75. Longitudinal t
. Fossil plants : for students of botany and geology . Paleobotany. X] ARTHROPITYS. 313 result of active growth, and not merely the expression of the tangential stretching of the stem consequent on secondary thickening. A glance at the complete transverse section of the stem,— of which a small portion is shown in fig. 74 A,—suggests the existence of annual rings in the wood, but this appearance of rings is merely the result of compression. The secondary wood of a Calamite does not exhibit any regular zones of growth comparable with the annual rings of our forest Fig. 75. Longitudinal tangential Beetion near the inner edge of the wood of the Calamite of iig. 74. X, X, secondary xylem and medullary rays; m, principal medullary ray. From a section in the Binney Collection, x 50. Before passing to other examples of Calamitean stems, refer- ence may be made to the sections shown in figs. 75 and 76, which illustrate some further points in the structure of Binney's stems. In fig. 75 the xylem tracheids are shown at x, and between them the secondary medullary rays present the appearance of. 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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Keywords: ., bookcentury1800, bookdecade1890, bookpublishercambr, bookyear1898
