. Beginnings in agriculture. Agriculture. THE NATURE OF PLANTS 113 supported by the food that has been stored in the branches, twigs, and buds during the previous season. Protoplasm. — What has become of the mineral foods carried into the plant and up to the leaves in the soil water ? In the leaves the soil water meets the liquid containing the substances which have been taken in from the air. These two liquids unite, and there is formed a product called proto- plasm. Protoplasm is the real living matter in plants. It con- tains sulfur, phosphorus, potas- sium, and other elements. It exists in
. Beginnings in agriculture. Agriculture. THE NATURE OF PLANTS 113 supported by the food that has been stored in the branches, twigs, and buds during the previous season. Protoplasm. — What has become of the mineral foods carried into the plant and up to the leaves in the soil water ? In the leaves the soil water meets the liquid containing the substances which have been taken in from the air. These two liquids unite, and there is formed a product called proto- plasm. Protoplasm is the real living matter in plants. It con- tains sulfur, phosphorus, potas- sium, and other elements. It exists in the plant cells, where it stimulates all the activities of the plant. Transpiration. — In Chap- ter XI we learned that crops take from the soil 300 to 500 tons of water to make one ton of dry plant substance. Some of this water is used in the plants in dissolving and circulating the foods, and in keeping the plants " fresh," and strong. But much more water is taken into tne plant than is needed. The sur- plus is given off from the leaves into the atmosphere by evapora- tion. This process is known as ''transpiration"; that is, the leaves transpire or give off mois- ture. If the leaves give off more moisture than the roots supply, the plant wilts. The water is then taken out of the cells, out of the circulatory system, and the cells collapse. This teaches us again the necessity of an abundance of moisture in the Fig. 53. — The effect of transpiration. The sHp on the left has lost its mois- ture by transpiration, and has wilted. On the right, the upper tumbler has prevented nmch of the transpiration, and the slip is still 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 Mann, Albert Russell, 1880-. New York, Macmillan company
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Keywords: ., bookcentury1900, bookdecade1910, bookpubl, booksubjectagriculture
