File:Organography of plants, especially of the archegoniatae and spermaphyta (1900) (14594017597).jpg

Identifier: organographyofpl02goeb (find matches)
Title: Organography of plants, especially of the archegoniatae and spermaphyta
Year: 1900 (1900s)
Authors: Goebel, Karl, 1855-1932
Subjects: Plant anatomy
Publisher: Oxford, Clar. Press
Contributing Library: Robarts - University of Toronto
Digitizing Sponsor: University of Toronto

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xxii (1S96), p. 333. The marginalantheridia of Ceratopteris are half-embedded. It is characteristic that the cell-structure of the antheridium of these two genera diverges fromthat of Lygodium, which conforms with the type of Polypodiaceae. COEBEL II JT 178 SEXUAL ORGANS OF PTERIDOPHYTA HOMOSPOROUS PTERIDOPHYTA. In the first place, the spermatocytesalways arise in one mother-cell in both the embedded and the free anther-idia. In the embedded antheridia (Fig. 133, VI), the mother-cell of theantheridium divides by a periclinal wall into an outer cell, d, which formsthe wall, and an inner cell, M, from which the spermatozoids are derived. Equisetum. Now in Equisetum the formation of the antheridium maytake place upon a cell-filament or cell-surface, although it commonly occursupon a prothallus which has become a cell-mass. Where the former is thecase a cell-mass must be first of all formed in some measure, and to thisend frequently one cell divides in the manner diagrammatically shown in
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Fig. 133. Scheme of development of the antheridium. I, Aneimia. II, Polypodiaceae. Ill, Osmundaceae.IV, V, Equisetum. Development upon a cell-thread of which the end-cell is seen in IV in longitudinal section, in Vfrom above. VI, Equisetum. Development upon a cell-mass. 4/, in all figures, the spermatocytes; d, theopercular cell ; i, 2, 3, 4, successive division-walls. Further explanation in the text. Fig. 133, IV, V, that is to say, division-walls are formed in three differentdirections so as to cut off a tetrahedral central cell with curved walls, andthis is the mother-cell of the antheridium ; this mother-cell then divides intothe spermatocyte and the opercular cell, which undergoes further division.The cells cut off to the outside by the walls i, 2, and 3, are not distinguishedby any special features from other cells of the prothallus, whilst the oper-cular cells are so distinguished, markedly by their behaviour in the openingof the antheridium. We must therefore consider the firs

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