. Foundations of botany. Botany; Botany. FUNCTIONS OF LEAVES 173 their life. For, Kke animals, plants get the energy with which they do the work of assimilation, growth, reproduc- tion, and performing their movements from the oxidation of such combustible substances as oil, starch, and sugar.^ The amount of oxy- gen absorbed and of car- bonic acid given off is, however, so trifling com- pared with the amount of each gas passing in the opposite direction, while starch-making is going on in sunlight, that under such circum- stances it is difficult to observe the occurrence of respiration. In ord
. Foundations of botany. Botany; Botany. FUNCTIONS OF LEAVES 173 their life. For, Kke animals, plants get the energy with which they do the work of assimilation, growth, reproduc- tion, and performing their movements from the oxidation of such combustible substances as oil, starch, and sugar.^ The amount of oxy- gen absorbed and of car- bonic acid given off is, however, so trifling com- pared with the amount of each gas passing in the opposite direction, while starch-making is going on in sunlight, that under such circum- stances it is difficult to observe the occurrence of respiration. In ordi- nary leafy plants the leaves (through their stomata) are the principal organs for absorption of air, but much air passes into the plant through the lenticels of the bark. In partly submerged aquatics especial provisions are found for carrying the air absorbed by the leaves down to the submerged parts. This is accomplished in pond lilies by ventilating tubes which traverse the leaf-stalks length- wise. In many cases such channels run up and down the stem (Fig. 124). 1 The necessity of an air supply about the roots of the plant may he shown by filling the pot or jar in which the hydrangea was grown for the transpi- ration experiment perfectly full of water and noting the subsequent appear- ance of the plant at periods twelve to twenty-four hours Fig. 124.—Gross-Seotion of Stem of Marestail (Hippuris) with Air-Faesages, 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; Eastwood, Alice, 1859-1953. Boston, Ginn & Co.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1901
