. Essentials of botany. Botany; Botany. 140 ESSENTIALS OF BOTANY 166. Assimilation. — Assimilation means the transforma- tion of food into the tissues of the plant. From the starch in the leaf, grape-sugar or malt-sugar is readily formed, and some of this in turn is apparently combined on the spot with nitrogen, sulphur, and phosphorus. These elements are de- rived from salts taken up by the roots and transported to the leaves. The details of the process are not understood, but the result of the combination of the sugars or similar sub- stances with suitable (very minute) proportions of nitrog
. Essentials of botany. Botany; Botany. 140 ESSENTIALS OF BOTANY 166. Assimilation. — Assimilation means the transforma- tion of food into the tissues of the plant. From the starch in the leaf, grape-sugar or malt-sugar is readily formed, and some of this in turn is apparently combined on the spot with nitrogen, sulphur, and phosphorus. These elements are de- rived from salts taken up by the roots and transported to the leaves. The details of the process are not understood, but the result of the combination of the sugars or similar sub- stances with suitable (very minute) proportions of nitrogen, sulphur, and phosphorus is to form com- plex nitrogen compounds. These are not precisely of the same com- position as the living protoplasm of plant-cells or as the reserve proteids stored in seeds (Sect. 24), stems (Sect. 91), and other parts of plants, but are readily changed into protoplasm or proteid foods as necessity may demand. Assimilation is by no means confined to leaves; indeed, most of it, as above suggested, must take place in other parts of the plant. 167. Excretion of Water and Respiration. — Enough has been said in Sect. 159 concerning the former of these processes. Respiration, or consuming oxygen and giving off carbon dioxide, is an operation which goes on con- stantly in plants, as it does in animals, and is necessary to their life. For, like animals, plants get the energy with which they do the work of assimilation, growth, reproduc- tion, and performing their movements from the oxidation. Fig. 96. Leaf of Tropseolum partly covered with Disks of Corlc and exposed to 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 Bergen, Joseph Y. (Joseph Young), 1851-1917. Boston, Ginn
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