. Studies in fossil botany . Paleobotany. 22 STUDIES IN FOSSIL BOTANY preserved at the very commencement, or even before the commencement, of secondary growth, as shown in Fig. 5. This is a comparatively rare stage to find, and when it is found, it is nearly always in a small twig. The larger stems of Catamites are rarely, if ever, met with at so early a stage of development. In a twig in this early condition, before secondary thickening has begun, the pith is often persistent (though fistular in the specimen figured), and round it we find a ring of. Fig. 5.—Calaviites, sp. Transverse section
. Studies in fossil botany . Paleobotany. 22 STUDIES IN FOSSIL BOTANY preserved at the very commencement, or even before the commencement, of secondary growth, as shown in Fig. 5. This is a comparatively rare stage to find, and when it is found, it is nearly always in a small twig. The larger stems of Catamites are rarely, if ever, met with at so early a stage of development. In a twig in this early condition, before secondary thickening has begun, the pith is often persistent (though fistular in the specimen figured), and round it we find a ring of. Fig. 5.—Calaviites, sp. Transverse section of a very young twig, showing primary structure, c, cortex ; 7'/', vascular bundles, of which there are twelve, each with its canal. X nearly 40. Fhil. Trans., W. and S. Will. Coll. r56r. primary vascular bundles, in which the wood is but little developed, and then the cortex. The whole structure is strikingly like that of the stem of an Equisctum} Now one of the most important questions to be settled, bearing on the comparison with recent Equisetaceae, is this : Are these canals in Catamites really homologous with the carinal canals of an Equisc- tum, or are they of a different nature, perhaps, as some observers formerly thought, representing the phloem ? It has been observed that, in many cases, in the 1 Cp. Scott, Structural Botany, Part II. Fig. 39, showing the transverse section of a small stem of Equiseium 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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