. The great world's farm; some account of nature's crops and how they are grown. Natural history. Leaves and their Work 171 covered with beech-forest, all this gas, even though it amounts to billions of tons, would be gone in eight years ! For one acre of beechwood takes about a ton of carbon every year; and to supply one ton of carbon, three and a half tons of carbon-dioxide gas are neces- sary. This is taken up not only by the leaves, but by all the green parts of a plant, leaves, buds, stems, and fruit, so long as these remain green ; for it is only in the cells which contain leaf-green tha
. The great world's farm; some account of nature's crops and how they are grown. Natural history. Leaves and their Work 171 covered with beech-forest, all this gas, even though it amounts to billions of tons, would be gone in eight years ! For one acre of beechwood takes about a ton of carbon every year; and to supply one ton of carbon, three and a half tons of carbon-dioxide gas are neces- sary. This is taken up not only by the leaves, but by all the green parts of a plant, leaves, buds, stems, and fruit, so long as these remain green ; for it is only in the cells which contain leaf-green that starch is manufactured from the gas. These green cells lie im- mediately underneath the thicker-walled but transparent. Surface leaf-cells, with pores, magnified. cells of the surface which compose the skin; and through the skin the gas finds its way into them. The leaf-pores, by which water escapes, are openings in the skin formed by two curved, lip-like cells, which gape open in hot, bright weather, and close more or less in rain, damp, and darkness ; and it is when they open most widely that the manufacture of food goes on most briskly. For it is then that most carbon is separated, and most food is pumped up from the roots, as that is the time when the plant transpires most, and in this way both kinds of food are received together. When there is much transpiration, and water containing dissolved food is pumped up rapidly, then also much carbon is received, and vice 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 Gaye, Selina. New York [etc. ] The Macmillan Company
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectnaturalhistory, booky
