. Comparative anatomy of the vegetative organs of the phanerogams and ferns;. Plant anatomy; Ferns. ANOMALOUS THICKENING IN DICOTYLEDONS AND GYMNOSPBRMS. 579 thicker. But later a change lakes place : a dry piece of a stem or branch of S. nux vomica of 135™™ diameter, which was investigated, had a bast zone about s"^"" thick, consisting of very many layers. Climbing species, such as S. toxifera, S. brachiata, &c., seem to form secondary bast in still larger quantities. The secondary layer of bast has, except in one essential point, the same structure, and shows the same pheno
. Comparative anatomy of the vegetative organs of the phanerogams and ferns;. Plant anatomy; Ferns. ANOMALOUS THICKENING IN DICOTYLEDONS AND GYMNOSPBRMS. 579 thicker. But later a change lakes place : a dry piece of a stem or branch of S. nux vomica of 135™™ diameter, which was investigated, had a bast zone about s"^"" thick, consisting of very many layers. Climbing species, such as S. toxifera, S. brachiata, &c., seem to form secondary bast in still larger quantities. The secondary layer of bast has, except in one essential point, the same structure, and shows the same phenomena of dilatation as in the Dicotyledons with normal growth. Especially in S. nux vomica, it consists of broad, uniformly delicate, parenchymatous medullary rays, without stony elements, and between these run narrow bands, corresponding to the strands of xylem, each consisting of a few longitudinal rows of elongated cells with oblique or horizontal ends, soft, rather .thick, lateral walls, with simple scattered pits, and delicate transverse walls. The strands are accompanied by numerous chambered sacs with crystals. Both bast fibres and sieve-tubes are entirely absent. The sieve-tubes are on the other hand situated in the wood. This has in the main the normal" structure of Dicotyledonous wood. It consists in the species in question of (i) broad, numerous, medullary rays, com- posed of procumbent cells; (2) narrow strands, and portions of strands of different grades, which are composed of irregularly alternating broad transverse zones of very thick and long wood-fibres on the one hand, and large-celled fascicular parenchyma with pitted vessels on the other. In the mass of wood, which by reason of this com- position appears, in a slightly magnified transverse section, to be marked with ir- regular bands, there he numerous strands, on an average about 0-30™'" thick, with a roundish, or broadly elliptical transverse section. They are scattered through the whole ann
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Keywords: ., bookcentury1800, bookdecad, booksubjectplantanatomy, bookyear1884
