. Studies in fossil botany . Paleobotany. STIGMARIA 245 The regular radial seriation of the secondary xylem- elements is sometimes interrupted by the intercalation of a tangential band of much smaller tracheae, beyond. Fig. 99.—Stigmaria ficoides. Part of tangential section through wood, showing an outgoing rootlet-bundle. All the tracheides are scalariform. , medullary rays ; J>x, protoxylem of rootlet-bundle. The top of the figure is directed towards the base of the Stigmaria. X 40. Spencer Coll. 150 (now S. Coll. 1469). (G. T. G.) which the regular formation of large elements recom- m
. Studies in fossil botany . Paleobotany. STIGMARIA 245 The regular radial seriation of the secondary xylem- elements is sometimes interrupted by the intercalation of a tangential band of much smaller tracheae, beyond. Fig. 99.—Stigmaria ficoides. Part of tangential section through wood, showing an outgoing rootlet-bundle. All the tracheides are scalariform. , medullary rays ; J>x, protoxylem of rootlet-bundle. The top of the figure is directed towards the base of the Stigmaria. X 40. Spencer Coll. 150 (now S. Coll. 1469). (G. T. G.) which the regular formation of large elements recom- mences. These interruptions no doubt point to a break in the activity of the cambium, but the small- celled layers are not always continuous, and cannot be regarded as marking annual rings. To use Williamson's. 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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