. Fossil plants : for students of botany and geology . Paleobotany. 320 CALAMITES. [CH. It is well known how a wound on the branch of a forest tree becoihes gradually overgrown by the activity of the cambium giving rise to a thick callus, which gradually closes over the. Fig. 80. Diagrammatic sketch of a transverse section of a Calamite twig, showing callus wood. From a specimen in the Cambridge Botanical Laboratory Collection, x ca. 10. wounded surface in the form of two lips of wood which finally meet over the middle of the scar. The two lips of callus are clearly shown in the fossil branch
. Fossil plants : for students of botany and geology . Paleobotany. 320 CALAMITES. [CH. It is well known how a wound on the branch of a forest tree becoihes gradually overgrown by the activity of the cambium giving rise to a thick callus, which gradually closes over the. Fig. 80. Diagrammatic sketch of a transverse section of a Calamite twig, showing callus wood. From a specimen in the Cambridge Botanical Laboratory Collection, x ca. 10. wounded surface in the form of two lips of wood which finally meet over the middle of the scar. The two lips of callus are clearly shown in the fossil branch arching over the tear in the wood just beyond the ring of carinal canals. The tissue external to the wood represents the imperfectly preserved cortex. A section which was cut parallel to that of fig. 80 shows a con- tinuous band of wood beyond the wound, and the latter has the form of a small triangular gap; this section appears to have passed across the wound where it was narrower and has already been closed over by the callus. The formation of a rather different kind of callus wood has been described by Renault' and by Williamson and Scott^, in stems where aborted or deciduous branches have been overgrown and sealed up by cambial activity. ' Eenault (96), p. 91. ^ Williamson and Scott, loc. cit. p. 893. Vide specimens 133*—135* in the Williamson 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
