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Bijdrage tot de kennis van de vegetatieve celdeling bij de hogere planten

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equatorial thickenings of these fibres. In this and in similar cases among higher plants, the conclusion seems justifiable that the cell-plate is formed by homogeneous plasma which is conveyed to the cell-plate region and deposited there by the connecting fibres. In Dicti/ota there are no connecting fibres, neither does the cell-plate consist, at first, of a row of granules which split later to form the two plasmamembranes as described by Strasburger ('97 p. 359) for Fucus. The cell-plate does contain very small granules, similar to those observed everywhere in the framework to the cytoplasm, but in Didi/ota they are not arranged in a definite plane to form a cellplate. Their part in the proces is secondary." Hoe vormt zich de celplaat dan wel bij Dictyota? Er is hier geen spoor van verbindingsdraden. „The first visible tracé of a cell-plate is manifested by the transverse walls of the alveolae becoming perceptibly thicker and arranging theniselves in such a way as to appear as an uneven or somewhat zig zag line in section (Fig. 16) . . . At first certain of the alveolar walls are thinner than others, so that the cell-plate seems interrupted at those places, but eventually and gradually it attains a uniform thickness. Very soon the cell-plate or plasma-membrane is a uniform plane which in section appears as a smooth line1):"

Zoals Mottier dan ook opmerkt, komen de verschijnselen hier zeer veel overeen met die bij de Sphacelariaceeën (vgl. pag. 26).

Ook Grégoire en Berghs2) zijn het niet met de boven geciteerde beschouwing van Strasburger eens, altans voor zover het de vorming van de celplaat bij Pellia betreft:

„De plus, étant donnés les grands écartements qui

!) 1. c. pag. 181.

2) Grégoire et Berghs. La figure achromatique dans le Pellia epiphylla. La Celluie t. 21, 1904, p. 218.