Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1903 Excerpt: ... pairs of opposite leaves, the petioles of which had a length of about 2.5 to 4 cm., and the small laminae measured 2 by 1.5 cm. being extended, and about one sixth of the normal size. (See Fig. 148.) F1g. 148. Acer rubrum. A, etiolated branch with leaves. /?, normal greenleaf. The anatomical changes which may be ascribed to the effects of etiolation in Acer were more nearly parallel to Cornus than to uercus or Hicoria. The subepidermal layers of cork were present, and the formation of lenticels had begun in the basal internodes of the etiolated stems. Such lenticels were larger and more numerous than in the stems of old trees in the open, but bore a general resemblance in occurrence and form to those on juvenile sprouts. The walls of the epidermal and underlying tissues of etiolated twigs were slightly tinged with brown and the reddish cell contents of the normal epidermis were entirely lacking. The outline of the cross section of the normal twig is distinctly angular while in the juvenile and etiolated stems it was nearly circular. The subepidermal corky layers were present in the juvenile, adult and etiolated branches, the underlying cortex being thickened collenchymatously, pitted, and containing chlorophyl in the two normal forms, while in the etiolated the cortical cells were but slightly thickened, being flattened radially, with some intercellular spaces. The etiolated twigs showed, but a faint development of bast fibers, which with the lack of development of the collenchyma, must account for the mechanical weakness of such stems. The cambium layer is well marked in three kinds of branches, the wood cells and vessels showing larger lumina and thinner walls than the normal, although not so large as in the juvenile forms. The same may be said of the pi...
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