. Text-book of botany, morphological and physiological. Botany. 26 MORPHOLOGY OF THE CELL. are the angles of contiguous cells. The formation of such a scalariform thickening begins by the growth, on the thin wall which separates two vessels (C, /), of transverse ridges (v)t which unite on either side with the thickening which always lies at the angle of a cell-wall. C shows this in front view, D in vertical section. When com- pletely developed, the thin cell-wall (/) is absorbed (c, c, in B), the thickening-ridges have overarched, so that only a narrow fissure (B} d) remains between their marg
. Text-book of botany, morphological and physiological. Botany. 26 MORPHOLOGY OF THE CELL. are the angles of contiguous cells. The formation of such a scalariform thickening begins by the growth, on the thin wall which separates two vessels (C, /), of transverse ridges (v)t which unite on either side with the thickening which always lies at the angle of a cell-wall. C shows this in front view, D in vertical section. When com- pletely developed, the thin cell-wall (/) is absorbed (c, c, in B), the thickening-ridges have overarched, so that only a narrow fissure (B} d) remains between their margins; still further inwards the ridge again becomes narrower. The interior cavities of two adjoining vessels are thus united by,a number of long narrow fissures (B, j) ; the frame- work of the ladder is formed of peculiarly-shaped rungs, which may be seen in B at c c in section, at e in front view. Where the wall of a vessel bounds a parenchymatous cell (E), the scalariform thickening takes place only on one side of the vessel (g), and is absent from the other side (p). In this case also the thin original wall remains, closing externally the space of the fissure-like pit. The variety in the formation of pits is by no means exhausted by these examples; but all the processes cannot be described here; we can only indicate a FIG. 25.—Wall of a vessel with bordered pits from the tuberous root of the Dahlia; A front view of the wall of a vessel ; B transverse section of the same (hori- zontal, at right angles to the paper); C longitudinal section (vertical, at right angles to the paper); q septum; a the original thickening-ridges; b the overarching part of the thickening-masses ; c the fissure through which the cavity of the pit communicates with the cell-cavity. At a and £ the corresponding front view is appended in order to make the transverse and longitudinal sections more clear (X 800).. Please note that these images are extracted from scanned page images that
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1882
