. Studies in fossil botany . Paleobotany. LEPIDODENDRON iSi The secondary vascular tissues began to develop rather later than the periderm. Very often the new growth began on one side of the central cylinder, so that for a time the secondary wood formed a crescent, and not a complete ring (cf. Fig. 60) ; in other cases it was fairly equal all round from the first. The cambial. Fig. 61.—Lepidodendron selaginoides. Part of radial section, showing primary wood on left, and secondary wood, with medullary rays, on right; the narrow elements between the two are the protoxylem. X about 25. From a pho
. Studies in fossil botany . Paleobotany. LEPIDODENDRON iSi The secondary vascular tissues began to develop rather later than the periderm. Very often the new growth began on one side of the central cylinder, so that for a time the secondary wood formed a crescent, and not a complete ring (cf. Fig. 60) ; in other cases it was fairly equal all round from the first. The cambial. Fig. 61.—Lepidodendron selaginoides. Part of radial section, showing primary wood on left, and secondary wood, with medullary rays, on right; the narrow elements between the two are the protoxylem. X about 25. From a photograph by Dr. Bousfield. S. Coll. 24. divisions started in the conjunctive tissue between the primary wood and phloem ; the very first beginning of the new formation can be traced in some of the specimens (see Fig. 60, on lower side of figure). The secondary wood usually abuts directly on the small external tracheides of the primary ring (see longi- tudinal section, Fig. 61); sometimes a layer 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 Scott, Dukinfield Henry, 1854-1934. London, A. and C. Black
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