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slow, and resemble those of Amoebse or of the white corpuscles of the blood. We may therefore conclude that they consist of protoplasm.[1] If their shapes are sketched at intervals of
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Fig. 7.
(Drosera rotundifolia.)
Diagram of the same cell of a tentacle, showing the varions forms successively assumed by the aggregated masses of protoplasm.
a few minutes, they are invariably seen to have undergone great changes of form; and the same cell has been observed for several hours. Eight rude, though accurate sketches of
the same cell, made at intervals of between 2 m. or 3 m..
- ↑ [This conclusion has been
shown to be erroneous: there can
be no doubt that the aggregated
masses are concentrations or precipitations
of the cell-sap, and
that their supposed amoeboid
movements are the result of the
streaming protoplasm, which
monids the passive masses into a
variety of forms.
Pfeffer was the first to insist on this view of the nature of aggregation. In his 'Osmotische Untersuchunpen' (1877). Since then the subject has been investigated by Schimper ('Botanische Zeitung.' 1882. p. 233), who describes the aggregated masses as concentrations of cell-sap, rich in tannin, and floating in the swollen and transparent protoplasm.
Schimper's observations are confirmed by Gardiner ('Proc. Royal Soc.,' Nov. 19. 1885,' No. 240. 1886), who describes the protoplasm in the stalk-cells of Drosera dichotoma as swelling up by the absorption of the "water from Its own vacuole," and thus leaving the tannin in cell-sap in a concentrated condition. Gardiner has added some curious observations on the connection between aggregation and the condition of the cell as regards turgidity. He supposes that aggregation is connected with a loss of water, and that an aggregated cell is in a condition of diminished turgidity. This is supported by his observation that "injection of water into the tissue will at once stop aggregation, and restore the cell to its normal condition." These changes are connected with certain alterations of form occurring in the above-mentioned body described by Gardiner under the name of rhabdoid, and which seems to be peculiarly sensitive to changes in the turgidity, so much so indeed that the author utilises it as a "turgometer," or index of the degree of turgescence.
H. de Vries has also written on the subject of aggregation ('Botanische Zeitung,' 1880, p. 1), and his views agree with those of Pfeffer, Schimper, and Gardiner as to the main fact that the aggregated masses are concentrations of cell-sap. In some other respects they differ from the conclusions of these authors.
De Vries believes that in Drosera and in vegetable cells generally the vacuoles are surrounded by a special protoplasmie wall, distinct from the layer of flowing protoplasm
