. Gray's school and field book of botany. Consisting of "Lessons in botany," and "Field, forest, and garden botany," bound in one volume. Botany; Botany. much thickened and the calibre small. The protoplasm of each living cell appears to be completely shut up and isolated in its shell of cellulose; but microscopic investigation has brought to view, in many cases, minute threads of protoplasm which here and there traverse the cell-wall through minute pores, thus connecting the living portion of one ceE with that of adjacent cells. (See Fig. 447, &c.) 403. The hairs of pl
. Gray's school and field book of botany. Consisting of "Lessons in botany," and "Field, forest, and garden botany," bound in one volume. Botany; Botany. much thickened and the calibre small. The protoplasm of each living cell appears to be completely shut up and isolated in its shell of cellulose; but microscopic investigation has brought to view, in many cases, minute threads of protoplasm which here and there traverse the cell-wall through minute pores, thus connecting the living portion of one ceE with that of adjacent cells. (See Fig. 447, &c.) 403. The hairs of plants are cells formed on the surface; either elongated single cells (Uke the root-hairs of Fig. 441, 443), or a row of shorter cells. Cotton fibres are long and simple cells grow- ing from tiie surface of the seed. 404. Tlie size of the cells of which common plants are made up varies from about the thirtieth to the thou- sandth of an inch in diameter. An ordinary size of short or roundish cells is from ^J^ to yj^ of an inch ; so that there may generally be from 27 to 125 millions of cells in the compass of a cubic inch! 405. Some parts are built up as a compact structure ; in others cells are arranged so as to build up regular air- ^^BBBQClOCf^ channels, as in the stems of aquatic and other water-loving plaiits (Fig. 440), or to leave irregular spaces, as iu the lower part of most leaves, where the cells only here and there come into close contact (Fig. 443). 406. All such soft cellular tissue, Hke this of leaves, that of pith, and of the green bark, is called Parenchyma, while fibrous and woody parts are composed of PfiosEN- tOOCScnr^ CHTMA, that is, of peculiarly transformed 443 407. Strengthening Cells. Common cellular tissue, which makes up the whole structure of all very young plants, and the whole of Mosses and other vegetables of the lowest grade, even when full grown, is too tender or too brittle to give needful strength and toughness for plants which are to rise to any
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1887
