. Botanical gazette. Plants. IQlOl MILLER^LVCAS MEDIA 211 eter of cm. There is practically no tapering to the columnar trunk excepting at the very apex, while the pith actually increases in diameter as it nears the apex, until it finally merges into the plerome cylinder (fig. i). At the base of the stem there are 3 separate and distinct vascular cylinders, the normal one nearest the pith and the 2 corti- cal ones developed concen- trically about the normal. In previous accounts the first cortical cylinder has been reported to have a development of xylem and phloem equal to that of the norm
. Botanical gazette. Plants. IQlOl MILLER^LVCAS MEDIA 211 eter of cm. There is practically no tapering to the columnar trunk excepting at the very apex, while the pith actually increases in diameter as it nears the apex, until it finally merges into the plerome cylinder (fig. i). At the base of the stem there are 3 separate and distinct vascular cylinders, the normal one nearest the pith and the 2 corti- cal ones developed concen- trically about the normal. In previous accounts the first cortical cylinder has been reported to have a development of xylem and phloem equal to that of the normal cylinder, while the second and succeeding cor- tical cylinders diminish successiveh' in that devel- opment toward the periph- ery of the stem. 1 find in this stem, however, that, near the base, the first cor- tical cylinder has a greater radial extent of xylem and phloem than has the nor- mal one, while the second is about the equal of the normal, thus beginning the successive decrease of xylem and phloem develop- ment which would likely be continued further if other vascular cylinders were present (fig. 2). In each cylinder the xylem elements are of greater radial extent than phloem elements, the former occupying approximately three- fifths of the radial extent of the entire cylinder. At the stem apex only 2 vascular cylinders are evident (fig. 3). Here the normal cylinder is seen to have xylem and phloem of slightlv less radial extent than it has near the stem base, while. //; Fig. I.—Cycas media: showing radial and transverse aspects of polyxylic stem near tip; »?, pith; p, plerome; .r, xylem; ph, phloem; c, 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 Hanover, Ind. : J. M. Coulter
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