. Physiological botany; I. Outlines of the histology of phænogamous plants. II. Vegetable physiology. Plant physiology; Plant anatomy. 382 VEGETABLE GROWTH. 1. Periclinal, those which exhibit in longitudinal section curves in the same direction as the surface. 2. Anticlinal, those wliich cut the surface and the periclinal walls at right angles (forming a sj'stem of orthogonal trajecto- ries for the periclinal walls). 3. Radial, those which pass through the axis of growth and cut the surface at right angles. 4. Transverse, those which cut both the axis of growth and the surface at right angles.
. Physiological botany; I. Outlines of the histology of phænogamous plants. II. Vegetable physiology. Plant physiology; Plant anatomy. 382 VEGETABLE GROWTH. 1. Periclinal, those which exhibit in longitudinal section curves in the same direction as the surface. 2. Anticlinal, those wliich cut the surface and the periclinal walls at right angles (forming a sj'stem of orthogonal trajecto- ries for the periclinal walls). 3. Radial, those which pass through the axis of growth and cut the surface at right angles. 4. Transverse, those which cut both the axis of growth and the surface at right angles. 1003. Growth of the cell-wall. When the new cell is formed it undergoes changes in size, and often in shape and thickness. If it increases in size regularlj' at all points of the surface, it preserves, of course, its original shape ; but if its growth is irregular at different points, great modifications of form re- sult. Pollen-grains afford instances of the former method of growth, while the latter is seen in the multicellular organs, for example stems and leaves. At the growing points of the stem and leaf tiie cells when first formed are nearly alike in appear- ance ; but wide differ- ences are soon presented. The growth of a cell in size may be terminal, when it gives rise to elongated forms ; or lo- ^^"^-^ calized at a point, line, or zone, when projections and swellings of various kinds are produced.^ Arteiten des botan. Inst, in Wiirzliurg, 1878, in appendix to Text-book, 2d Eng. ed., p. 951), The student should also read Sachs's Vorlesungen, 1882, pp. 523-557. 1 These have already hcen sufficiently considered in the histological part of this volume, and it is not necessary to again call attention to the adaptations of the resultant structures to their respective kinds of work in the organism. Fig. 168. Arc-auxanometer /, tliread connecting plant witli short arm of lever a z. The weight of long arm balanced by movable weight at k. (Pfeffer.). Please note that thes
Size: 1286px × 1943px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectplantanatomy, bookyea
