. Comparative anatomy of the vegetative organs of the phanerogams and ferns;. Plant anatomy; Ferns. 33^ PRIMARY ARRANGEMENT OF TISSUES. fluitans. The structure is similar to that of the preceding species, but simpler, ^x trachea with annular and loosely spiral fibres, bordering on an intercellular passage in which the letter is written, g wider tracheae with densely spiral and reticulated wall, j- five relatively large sieve-tubes between narrow cambiform cells. The whole bundle is surrounded by narrow elongated prismatic cells, showing non-lignified cellulose walls, and these pass over gradua
. Comparative anatomy of the vegetative organs of the phanerogams and ferns;. Plant anatomy; Ferns. 33^ PRIMARY ARRANGEMENT OF TISSUES. fluitans. The structure is similar to that of the preceding species, but simpler, ^x trachea with annular and loosely spiral fibres, bordering on an intercellular passage in which the letter is written, g wider tracheae with densely spiral and reticulated wall, j- five relatively large sieve-tubes between narrow cambiform cells. The whole bundle is surrounded by narrow elongated prismatic cells, showing non-lignified cellulose walls, and these pass over gradually on the outside into large-celled parenchyma with abundant starch. As regards the surrounding layer marked a it remained doubtful whether it has an indi- cation of endodermal structure on those walls which are radial with reference to the bundle. Figs. 154 and 155, from the fully elongated hypocotyledonary stem of Ricinus communis (from Sachs' Textbook), represent that form of bundle, with radially disposed xylem, which predominates among Dicotyledons, together with the initial stages of the secondary growth in thickness, which here follows immediately on the formation of the primary bundles. In the cross-section (Fig. 154)^,*,? are the rows of vessels alternating with rows of thick-walled cells, beginning at the inner edge of the bundle with the primitive elements, which are distinguished by the thick shaded walls, t narrower, g wider pitted vessels. y phloem consisting of sieve-tubes, cambiform and delicate parenchyma, with three bundles of sclerenchymatous fibres on its outer border, at b. On the boundary between xylem and phloem, the formation of the zone of cambium and secondary growth {c-c) has begun by means of tangential divisions, and is continued, starting from the sides of the vascular bundle, over the parenchymatous zone cb, cb: cf. Chap. XIV. m parenchyma of the. Fig. 153. pith, r of the outer cortex. Between the layers containing the letters b and r is the pare
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Keywords: ., bookcentury1800, bookdecad, booksubjectplantanatomy, bookyear1884
