Nature and development of plants . integument becomes quite soft and water is readil) drawnthrough it owing to the fact that the storage foods in the embryo are in close COntad with it and draw the water through 1> mosis. Carefully removing the integument from a soaked beanwe note that the embryo is will developed, consisting of twofleshy cotyledons ami a short stem (Fig. 83, /. / 1. The epi-cotyl is well developed forming a plumule bearing two leaves and the short hypOCOtyl and rout are enclosed in a sheath formed from the integument. Note that the hypocotyl and root aresituated near tin-
Nature and development of plants . integument becomes quite soft and water is readil) drawnthrough it owing to the fact that the storage foods in the embryo are in close COntad with it and draw the water through 1> mosis. Carefully removing the integument from a soaked beanwe note that the embryo is will developed, consisting of twofleshy cotyledons ami a short stem (Fig. 83, /. / 1. The epi-cotyl is well developed forming a plumule bearing two leaves and the short hypOCOtyl and rout are enclosed in a sheath formed from the integument. Note that the hypocotyl and root aresituated near tin- micropyle. Ilow- does this arrangement work NATURE OF PLANTS 117 to the advantage of the embryo? Allow the seed to germinateand it will be noted that the absorption of water first causes theembryo to expand and rupture the integument. This is im-mediately followed by the growth and elongation of the lowerpart of the hypocotyl which results in the pushing out of the root(Fig. 84, A). Thus it happens that the very part of the embryo. Fig. 84. Renewal of growth of the bean seed: A, basal region of hypo-cotyl elongating and pushing the root into the soil. B, upper region of thehypocotyl elongating, lifting the cotyledons and epicotyl above the , hypocotyl erect and epicotyl expanding, forming the first normal leaves. that shows the first signs of growth is in close proximity to thewater as it enters the seed and doubtless the sheath also assistsin retaining water in this region. We are already familiar withthe properties of the root which direct its growth in such a waythat no matter how the seed may be placed the root will ulti-mately grow into the soil and toward water and the soil foods,page 54. It is noteworthy that many seeds are so fashionedthat they naturally assume such a position on the ground as tobring the root as it emerges into direct contact with the an arrangement is equally advantageous for the absorptionof water. How many seeds can you find that wil
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