Remarks on the so-called woody and vascular tissues of ferns / by George Ogilvie.

  • Ogilvie, George.
Date:
1860
Catalogue details

Licence: Public Domain Mark

Credit: Remarks on the so-called woody and vascular tissues of ferns / by George Ogilvie. Source: Wellcome Collection.

    13/26 (page 11)
    masses of dark tissue. In his remarks on the strueture of the stems of Ferns, in his ‘ Introduction to Cryptogamic Botany ^ (p. 515), he states distinctly that the hard tracts belong to the })arenehyma, and do not correspond to the proper wood of the Fhanerogamia. The latter he considers to be represented by certain pale fibres, occurring in the substance of the vascular bundles. 1 have recognized such fibres distinctly enough in two s])ecies of Tree-fern which 1 have lately examined. They form a sort of surface-coating to the fasciculi, exterior to the scalari- forrn vessels, and immediately within the cambium-layer. This is just the position occupied by the pleurenchyma of the Endo¬ genous stern; but in themselves these fibres have none of the characters of woody tissue. They appear to be portions of the cambium-layer which have undergone an imperfect conversion into vascular tissue. The transformation seems to take place by the clustering of the minute cambium-cells into long fusiform masses, which then become invested by a cell-wall, on whose inner surface the scalariforin markings are developed, by a deposit of cellulose at particular points, pari passu with the disappear¬ ance of the original cells of the cluster enclosed by it. I think I have observed all stages of this transition—fusiform masses of cellules, pale granular fibres, and tubules or elongated cells, differing from the scalariforin vessels of the fasciculus only in their smaller diameter and fainter markings. In most of our indigenous species I have been unable to re¬ cognize any distinct fibrous coating to the vascular bundles, though the inner stratum of the cambium-layer has certainly at times an appearance of faint longitudinal striation, and the sca- lariform vessels on the exterior of the fasciculus are generally of smaller diameter and less distinctly marked than those within. The striated layer comes nearest to the characters of a real fibrous tissue in the netted cylinder of Polystichum Lonchitis and Cysio- jitei'is frayilis, 'and in the indurated petiolar fasciculi of TricJio- manes radicans and Aspleniuui lanceolatum. In P. Lonchitis and A. lanceolatum some of these cambium-fibres make a still closer approach to those of woody tissue, by the deposit of a brown sclerogcnous matter in their interior. In Botrychiwn Lunaria similar fibres occur, and the vessels are rather annular than scalariforin. That the woody fibres of jilants generally differ from the ducts or vessels only in being a less-differentiated form of cambium- tissue, is a view which was very distinctly laid down by Schleideii*, and one which derives some support from the replacement of ducts by punctated woody tissue in the Conifcrie, and from the occurrence in some species of various intermediate forms, such * Principles of Botany, bk. 2. c. 2. § 2i\.