. College botany; structure, physiology and economics of plants. Botany. 166 COLLEGE BOTANY. the -wilting of the plank However, wiltiiig may be due to other causes, such as the loss of water by transpiration through the Osmosis ana Nutrient Salts.—The movement of water into and through the plant also involves the movement of the various salts which are dissolved in the water. The plasmatic membrane of the plant cell is permeable not ordy to the nutrient saltsi but also to many other substances, some of which may be neutral and others injurious. How- ever, it is impenetrable toi many
. College botany; structure, physiology and economics of plants. Botany. 166 COLLEGE BOTANY. the -wilting of the plank However, wiltiiig may be due to other causes, such as the loss of water by transpiration through the Osmosis ana Nutrient Salts.—The movement of water into and through the plant also involves the movement of the various salts which are dissolved in the water. The plasmatic membrane of the plant cell is permeable not ordy to the nutrient saltsi but also to many other substances, some of which may be neutral and others injurious. How- ever, it is impenetrable toi many sub- stances and is therefore somewhat se- lective in its functions. Some ma- FiG. 97.—Three of the ceUs terials tend to accumulate in the cells on the left are normal and one • 'iii i i -1,1 -1 piasmoiyzed; the cell of Spirogyra lu Considerable abundauce, although on the right is plasmolyzed. they may be of no value to the plant. Methylene blue in water at the rate of 1 part in 100,000 is not visible, but certain plants growing in the water will collect this material in appreciable amounts. Iodine is present in sea water at a dilution of about .000001 per cent., but certain sea alg-s will accumulate! it in such quantities that it can be recovered on a commercial basis. Sap and Root Pressure.—Water moves into the root system and up through the stem of the plant vdth considerable force. This becomes very evident when plants are pruned early in the spring and is referred to as bleeding. This phenomenon is known as sap and root pressure. It is very evident that the various falctors concerned with the absorption and movement of water in the plant, especially osmosis and turgor are im- portant factors in sap and root 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 Cook, Melville Thurston, 1869-
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