Text-book of botany, morphological and physiological . Fig. 30.—Brown-wailed cells jn the stem ofPteyis aqiuUna; A a half-cell isolated andrendered colourless by Schulzes macera-tion ; B a piece more strongly magnified(X550); the fissure-like pits are crossed;2. e. the fissure is twisted as the thickeningincreases ; at / side-view of a fissure, ap-pearing here as a simple channel, since itshows the narrow Fig. 31.—Transverse section of a bast-cell ofthe root-tuber oi Dahlia variabilis (x8oo);/the cell-cavity; Apit-channels which pene-trate the stratification ; sp a crack by whichan
Text-book of botany, morphological and physiological . Fig. 30.—Brown-wailed cells jn the stem ofPteyis aqiuUna; A a half-cell isolated andrendered colourless by Schulzes macera-tion ; B a piece more strongly magnified(X550); the fissure-like pits are crossed;2. e. the fissure is twisted as the thickeningincreases ; at / side-view of a fissure, ap-pearing here as a simple channel, since itshows the narrow Fig. 31.—Transverse section of a bast-cell ofthe root-tuber oi Dahlia variabilis (x8oo);/the cell-cavity; Apit-channels which pene-trate the stratification ; sp a crack by whichan inner system of layers has become sepa-rated. ^ A very clear representation of a twisted pit-channel, whose outer and inner fissure (within thesame cell-wall) cross, may be seen in Nageli, Berichte der Miinchener Akademie, 1867, vol. 45- THE CELL-WALL. 29 The corresponding growth in thickness is less marked if the thickenings show adistinctly spiral structure, or if they arise in the form of strong spiral bands, as in spiralfibre-cells ; if, in this case, in each pair of adjoining cells one or more spiral bands windin the same direction, they must necessarily cross on the common partition-wall. (c) Stratification and Striation of the Cell-wall \ When the cell-walls have at-tained a certain thickness and extent of surface, stratification and striation take placemore or less clearly. In consequence of
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1875
