. Class-book of botany : being outlines of the structure, physiology, and classification of plants ; with a flora of the United States and Canada . Botany; Botany; Botany. OF THE VEOBTABLB OKLL. 131. 657, Section of the rhizome of Blood-root, o, a. A bundW of wood-cells. The shaded cells contain the color. (1) spheroidal, like pollen grains, the red snow-plant, the cells of leaf- tissue, etc., varying to oblong, or lobed, or stellate ; (2) cylindrical, or tube-form, as most wood-cells are; (3) tabular or flattened, as the cells of the epidermis. 642. The casual forms result from external pres-
. Class-book of botany : being outlines of the structure, physiology, and classification of plants ; with a flora of the United States and Canada . Botany; Botany; Botany. OF THE VEOBTABLB OKLL. 131. 657, Section of the rhizome of Blood-root, o, a. A bundW of wood-cells. The shaded cells contain the color. (1) spheroidal, like pollen grains, the red snow-plant, the cells of leaf- tissue, etc., varying to oblong, or lobed, or stellate ; (2) cylindrical, or tube-form, as most wood-cells are; (3) tabular or flattened, as the cells of the epidermis. 642. The casual forms result from external pres- sure, as of cells crowding against cells, in stems or pith. In this way spher- oidal cells may become cu- bical, 8-sided, 12-sided, etc ; tubiform cells pris- matic, and tabular cells 4- angled, hexagonal, etc., in outline according to the original pattern. 643. In magnitude the plant eell varies from -pj-j to jj^ of an inch in diameter; the more cotnmon size is about jjj- inch. Tho cells of older pith measure about 2^5 inch; those of pa- renchyma (leaf-tissue) about ^^j consequently, 64,000,000 of them would occupy only one cubic inch. The cells of cork are computed to be y^Vir 'â ^'^'^ ⢠diameterâ 1000 millions to a cubic inch. 644. But the length of some cells is much more considerable. Wood-cells measure -g^ inch; bark cells, as flax, hemp, nearly J inch ; the cells of some plant- hairs an inch or more. 645. The wall of the new cell consists of two layers ; the outer one a firm, colorless membrane, made of cellulose, the inner a plastic, gelat- inous layer applied to the outer, and chiefly concerned in cell-life and multiplication. This is called the primordial utricle. 646. It is best seen when treated with a weak solution of nitric acid, iodine, or alcohol. It thus becomes colored, contracts, and lies loose in the cell. 647. The cell wall is easily permeated by fluids flowing in and out. It must, therefore, be regarded as porous; although it appears perfectly entire
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