. Carnegie Institution of Washington publication. 166 THE cap arc cut tf from them. I he outer cells of the root cap are very much enlarged and there is an evident space between the root and the surrounding tissues. The trace from the third leaf joins that of the second one close to its union with the bundle from the cotyledon (fig. 148, H). In fig. 150 are shown nine cross-sections from a series made from a plant of D. jamaicensis, in which four leaves win- evident. A microscopic examination of the stem apex showed, however, that a fifth leaf was also present, which stood nearly
. Carnegie Institution of Washington publication. 166 THE cap arc cut tf from them. I he outer cells of the root cap are very much enlarged and there is an evident space between the root and the surrounding tissues. The trace from the third leaf joins that of the second one close to its union with the bundle from the cotyledon (fig. 148, H). In fig. 150 are shown nine cross-sections from a series made from a plant of D. jamaicensis, in which four leaves win- evident. A microscopic examination of the stem apex showed, however, that a fifth leaf was also present, which stood nearly directly opposite the cotyledon. A shows sections only of leaves â¢; and 4, the latter having the stipules conspicuous, while these are absent or scarcely developed at all on the first three leaves, at least in the specimen in question. Between the leaves are seen sections of the numerous scales which beset the surface of the young leaves. B is taken somewhat lower down and includes a section of leaf 5. C passes through the stem apex and shows clearly the spiral arrangements of the first five leaves, each of which has in its petiole a single concentric bundle which becomes larger in. I'iG. 150. IK jamaii ensi â a ,miiu' sporophyte, with three fully-developed leaves an.! two jrounger ones. Section C pa through the stem apex. Roman figures indical ?e leavi each successive leaf, with a corresponding increase in the development of the xvlem. As the sections are examined, farthei ami farther down in the stem (/) to /â '), one can sir very clearly tin- way in which the single bundle in the lower part of the stem owes irsoii»in to the coalescence of the leaf traces. Proceeding downward th. traces of leaves 4 and ^ ate seen to approach gradually and finally to become completely coalescent; ami still further down (/â¢') the leaf trace from 3 joins that from 4, ami a smidc bundle results, crescent-form in section, but showing clearly its compound nature. The three x\ leins never
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Keywords: ., bookauthorcarnegie, bookcentury1900, bookdecade1910, bookyear1911
