. A text-book of botany for secondary schools. Botany. LEAVES 21. ing over the plants a large funnel and leading the bubbles into a test tube, in which the presence of oxygen can then be tested. It has been noted that photo- synthesis is associated not mere- ly with light but also with green tissue ; and in examining the structure of the leaf it was dis- covered (§13) that the green color is due to the presence of chloroplasts in the mesophyll cells. It is these chloroplasts that manufacture the carbo- hydrates, and they obtain from the light the power (energy) to do it. The first visible prod
. A text-book of botany for secondary schools. Botany. LEAVES 21. ing over the plants a large funnel and leading the bubbles into a test tube, in which the presence of oxygen can then be tested. It has been noted that photo- synthesis is associated not mere- ly with light but also with green tissue ; and in examining the structure of the leaf it was dis- covered (§13) that the green color is due to the presence of chloroplasts in the mesophyll cells. It is these chloroplasts that manufacture the carbo- hydrates, and they obtain from the light the power (energy) to do it. The first visible product of photosynthesis is starch, and when the working cells are very active starch may be observed to accumulate in them; but when the process becomes slower or stops, as during the night, this starch disappears, the food being carried away for use (Figs. 15 and 16).* A summarized statement of photosynthesis is as follows: It is the manufacture of carbohydrates by chloroplasts in the presence of Fig. geranium leaf, one- light, Water and carbon dioxide half of which has been cov- being used, and oxygeu being ered; the test shows absence . ^„ i of starch in the covered half. given off aS a Waste product. Fig. 15.—A bean leaf whose termi- nal leaflet has been covered and whose lateral leaflets have been exposed to light; the test shows an absence of starch in the former and an abundance of it in the 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 Coulter, John Merle, 1851-1928. New York, D. Appleton
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1906
