. The elements of botany for beginners and for schools. Plants. 150 VEGETABLE LIFE AND WORK. [SECTION x/JfR transparent aquatic plants and in hairs on the surface of land plants (where it is easiest to observe), that it may be inferred to take place in all cells during the most active part of their life. This motion is commonly a streaming movement of threads of protoplasm, carrying along solid granules by which the action may be ob- served and the rate measured, or in some cases it is a rotation of the whole protoplasmic contents of the cell. A comparatively low magnifying power will sho
. The elements of botany for beginners and for schools. Plants. 150 VEGETABLE LIFE AND WORK. [SECTION x/JfR transparent aquatic plants and in hairs on the surface of land plants (where it is easiest to observe), that it may be inferred to take place in all cells during the most active part of their life. This motion is commonly a streaming movement of threads of protoplasm, carrying along solid granules by which the action may be ob- served and the rate measured, or in some cases it is a rotation of the whole protoplasmic contents of the cell. A comparatively low magnifying power will show it in the cells of Nitella and Chara (which are cryptogamous plants) ; and under a moderate power it is well seen in the Tape Grass of fresh water, Vallisueria, and in Naias flexilis (Fig. 489). Minute particles and larger green- ish globules are seen to be carried along, as if in a cur- rent, around the cell, passing up one side, across the end, down the other and across the bottom, completing the circuit sometimes within a minute or less when well warmed. To see it well in the cell, which like a string of beads form the hairs on the stamens of Spiderwort, a high magnifying power is needed. 462. Transference of Liquid from Cell to Cell, and so from place to place in the plant, the absorption of water by the rootlets, and the exhalation of the greater part of it from the foliage, — these and similar operations are governed by the physical laws which regulate the diffusion of fluids, but are controlled by the action of living protoplasm. Equally under vital control are the various chemical transformations which attend assimilation and growth, and which involve not only molecular movements but conveyance. Growth itself, which is the formation and shaping of new parts, implies the direction of internal activities to definite ends. 463. Movements of Organs. The living protoplasm, in all but the lowest grade of plants, is enclosed and to common appearance isolated in separate ce
Size: 951px × 2627px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectplants, bookyear1887
