. How crops grow. A treatise on the chemical composition, structure, and life of the plant, for all students of agriculture ... Agricultural chemistry; Growth (Plants). 322 now CROPS GKOW. germinating seed, the change goes on at ordinary or even low temperatures. It is generally taught that oxygen acting on the album- inoids in presence of water and within a certain range of temperature induces the decomposition which confers on them the power in question. The necessity for oxygen in the act of germination has been thtis accounted for, as needful to the solution of the starch, etc., of the cot
. How crops grow. A treatise on the chemical composition, structure, and life of the plant, for all students of agriculture ... Agricultural chemistry; Growth (Plants). 322 now CROPS GKOW. germinating seed, the change goes on at ordinary or even low temperatures. It is generally taught that oxygen acting on the album- inoids in presence of water and within a certain range of temperature induces the decomposition which confers on them the power in question. The necessity for oxygen in the act of germination has been thtis accounted for, as needful to the solution of the starch, etc., of the cotyledons. This may be true at first, but, as we shall presently see, the chief action of oxygen is probably of another kind. How diastase or other similar substances accomplish the change in question is not certainly known. Soluble Starch.—The conversion of starch into sugar and dextrin is thus in a sense explained. This is not, how- ever, the only change of A^-hich starch is susceptible. In the bean, {Phaseolus muUiflorus), Sachs {Sitz- ungsberichte der Wiener Akad., XXXYII, 57) in- forms us that the starch of the cotyledons is dissolved, passes into the seedling, and reappears (in ^jart, at least) as starch, without conver- sion into dextrin or sugar, as these substances do not appear in the cotyledons during any period of germina- tion, except in small quantity near the joining of the seedling. Compare p. 64, Unorganized Starch. The same authority gives the following account of the microscopic changes observed in the starch-grains themselves, as they undergo solution. The starch-grains of the bean have a narrow interior cavity, (as seen in fig. 65, 1.) This at first becomes filled with a Fig. 65. Digitized by Microsoft®. 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 Johnson, Samuel William, 1
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectagricul, bookyear1868
