. Fossil plants : for students of botany and geology . Paleobotany. X] YOUNG STEM. 305 plants must constantly be on his guard against the possible misinterpretation of Stigmarian ' rootlets/ which are frequently- found in intimate association with fossil tissues. The intrusion of these rootlets is admirably illustrated by a section of a Cala- mite stem in the Williamson Collection (No. 1558) in which the hollow pith, 2 cm. broad, contains more than a dozen Stigmarian Fia. 71. Transverse section of a young Calamite stem, c, oariual canals; mr, primary medullary rays; u, b, and d, c
. Fossil plants : for students of botany and geology . Paleobotany. X] YOUNG STEM. 305 plants must constantly be on his guard against the possible misinterpretation of Stigmarian ' rootlets/ which are frequently- found in intimate association with fossil tissues. The intrusion of these rootlets is admirably illustrated by a section of a Cala- mite stem in the Williamson Collection (No. 1558) in which the hollow pith, 2 cm. broad, contains more than a dozen Stigmarian Fia. 71. Transverse section of a young Calamite stem, c, oariual canals; mr, primary medullary rays; u, b, and d, cortex; e, epidermis. From a section in the Manchester Museum, Owens College, x 60. In the figured specimen of a Calamite twig (fig. 71) there is a clearly marked differentiation into a cortical region and a large stele or central cylinder. The pith-cells are already partially disorganised, but there still remain a few fairly large parenchymatous cells internal to the ring of vascular bundles. The few irregular projections into the cavity of the large pith consist of small fragments of cells, which may be the result of fungal action. Mycelia of fungi are occasionally met with in the tissues of older Calamite stems. The position of the primary xylem groups is shown by the conspicuous and regularly placed canals, c; these have been s. 20. 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
