. Practical physiology of plants. Plant physiology; 1894. CH. V] ISOTONIC COEFFICIENT. 115 dandelion is split longitudinally into four strips which, on being dipped for a moment into water, curl up into spirals and can then be cut up into some 7 or 8 rings, b, fig. 21: these are delicate tests of changes in turgescence since a small increase or decrease in the curvature of the turgescent tissue is at once perceptible. Thus s is in too. to h FiQ. 21, Exp. 148. strong a solution, w is in too weak a solution, while h is in one that almost exactly balances the osmotic power of the cell sap. The ^d
. Practical physiology of plants. Plant physiology; 1894. CH. V] ISOTONIC COEFFICIENT. 115 dandelion is split longitudinally into four strips which, on being dipped for a moment into water, curl up into spirals and can then be cut up into some 7 or 8 rings, b, fig. 21: these are delicate tests of changes in turgescence since a small increase or decrease in the curvature of the turgescent tissue is at once perceptible. Thus s is in too. to h FiQ. 21, Exp. 148. strong a solution, w is in too weak a solution, while h is in one that almost exactly balances the osmotic power of the cell sap. The ^dcess with Rieinus is a little more troublesome ; the hypocotyl is split in 4 or more longitudinal portions, and the form of each is traced with a paint-brush (which answers better than a pencil) on paper. We now have a number of curved bits of tissue (whose form is known) each one of which must be placed in a solution of a different strength. These solutions are made according to equivalents, and in the case of KNO3 (which forms the standard) may contain 005, OlO, Oil, 0-12, 013, 014 gram-molecules per liter; stronger solutions may however be needed. After a quarter of an hour the result may be noted: if the material consist of dandelion rings the result is obvious on inspection; with Rieinus the seg- ments must be compared with the sketches. 8—2. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Darwin, Francis, Sir, 1848-1925; Acton, Edward Hamilton, d. 1895; Lindley, Nathaniel Lindley, Baron, 1828-1921. sgn. Cambridge, University Press
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectplantph, bookyear1894
