Text-book of botany, morphological and physiological . pt. (Sanio in Bot. Zeitg. p. 362, 1863.) ^ This distinction was first made by Schleiden, but he incorrectly ascribed to Dicotyledons ingeneral only open bundles; his distinction of simultaneous and successive cannot be sustained; allbundles become differentiated successively in transverse section. Sclileidens simultaneous bundlesof the higher Cryptogams belong to the closed description. 94 MORPHOLOGY OF TISSUES. plants possess closed bundles, or, if they are open, the activity of their cambiumsoon ceases. The different forms of tissue of a
Text-book of botany, morphological and physiological . pt. (Sanio in Bot. Zeitg. p. 362, 1863.) ^ This distinction was first made by Schleiden, but he incorrectly ascribed to Dicotyledons ingeneral only open bundles; his distinction of simultaneous and successive cannot be sustained; allbundles become differentiated successively in transverse section. Sclileidens simultaneous bundlesof the higher Cryptogams belong to the closed description. 94 MORPHOLOGY OF TISSUES. plants possess closed bundles, or, if they are open, the activity of their cambiumsoon ceases. The different forms of tissue of a differentiated fibro-vascular bundle may beclassified into two groups, which Nageli calls the Phloem- (Bast) and Xyle7n- (Wood)portion of the bundle. They are separated by the cambium if there is any. In manybundles the phloem is formed on one, the xylem on the other side of the procam-bium, and the development of both advances towards the centre of the bundle, whereat length they meet. The phloem consists of succulent, generally thin-walled cells ;. Fig. 8i.—Transverse section of a closed fibro-vascular bundle in the stem of maize (X550); fip the surrounding thin-walledparenchyma; a outer side, i inner side (facing the axis of the stem); g g two large pitted vessels; s spirally thickenedvessel; r isolated ring of an annular vessel; / air-containing cavity, from splitting caused by growth ; •z/z- the cambiform orlatticed cell-tissue which has passed over last into permanent tissue; between it and the vessel j lie reticulately thickenedand bordered pitted vessels; the periphery of the whole bundle forms a firm sheath of thick-walled lignified prosen-chyma-cells. only the bast-cells, which are often absent, but very often massively developed, areusually greatly thickened (mostly however not lignified but flexible). These thin-walledsucculent cells are either parenchymatous, or they are cambiform or latticed-cells, orfinally sieve-tubes. The xylem-portion of the fibro-vascula
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1875
