. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. 30 SIMPLE PITS layers formed by the protoplast of one cell, coincide with the thin areas on the outer sides of its walls, where the thickening has been deposited by the protoplasts of the surrounding cells. At these points, known as simple pits, the original middle lamella (the pit-mcnihrane, Fig. 14, A, pm.) alone separates the adjacent cells. In these cases the bulk of the protoplasmic connections (cf. p. 24) pass through the pit-membrane. Good examples of simple pits are seen in sections of Elder pith (Fig
. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. 30 SIMPLE PITS layers formed by the protoplast of one cell, coincide with the thin areas on the outer sides of its walls, where the thickening has been deposited by the protoplasts of the surrounding cells. At these points, known as simple pits, the original middle lamella (the pit-mcnihrane, Fig. 14, A, pm.) alone separates the adjacent cells. In these cases the bulk of the protoplasmic connections (cf. p. 24) pass through the pit-membrane. Good examples of simple pits are seen in sections of Elder pith (Fig. 14, B). In surface view they appear as irregularly scattered oval or elliptical areas which are more transparent. Fig. 14.—Thickened cell-walls. A, Portion of the endosperm of the Date in section. B, Pith-cell of the Elder. C, A group of stone-cells of the Pear, together with a small part of the adjacent flesh. D, Two isolated stone-cells, , middle lamella; p., pits seen in section ; pm., pit-membrane ; Ps., pits in surface view ; , stone-cells. than the rest [Ps.). In section (/>.) the walls appear broken at sundry points ; but careful focussing shows that the apparent gaps are really bridged by a thin line, the pit-membrane. In certain cases [ the endosperm of the Date (Fig. 14, A), the cotyledon-walls of the Lupine and many other Leguminosffi, and cells of the cortex of the Mistletoe] the thickening is so extreme that the cavity of the cell becomes much reduced, and the pits then appear as deep depressions within the wall. It is in such tissues that the protoplasmic connections between cell and cell can most readily be 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 Fritsch, Felix Eugene, 1879-; Salisbury, E. J. (Edward James), Sir, b. 1886. London, G. Bell and sons ltd.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectpl, booksubjectplants
