Insectivorous plants / by Charles Darwin ; revised by Francis Darwin.

  • Charles Darwin
Date:
1908
Catalogue details

Licence: In copyright

Credit: Insectivorous plants / by Charles Darwin ; revised by Francis Darwin. Source: Wellcome Collection.

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    simpler and commonest changes. The cell A, when first sketched, included two oval masses of purple protoplasm touching each other. These became separate, as shown at B, and then reunited, as at C. After the next interval a very common appearance was presented—D, namely, the formation of an extremely minute sphere at one end of an elongated Fig. 8. (Drosera rotundifolia.) Diagram of the same cell of a tentacle, showing the various forms successively assumed by the aggregated masses of protoplasm. mass. This rapidly increased in size, as shown in E, and was then reabsorbed, as at F, by which time another sphere had been formed at the opposite end. The cell drawn in fig. 7 was from a tentacle of a dark red leaf, which had caught a small moth, and was examined certain alterations of form occurring in the above-mentioned body de- scribed 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 “ turgo- meter,” or index of the degree of turgescence. H. de Vries has also written on the subject of aggregation Botan- ische Zeitung,’ 1886, p. 1), and his views agree with those of Pfetfer, 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 protoplasmic wall, distinct from the layer of flowing protoplasm which lines the walls. In the process of aggregation the vacuole expels a great part of its watery contents, retaining, however, the red colouring matter of the cell- sap, as well as tannin and albu- minous matter. The vacuole does not remain a single body, but divides into numerous secondary vacuoles. These are the aggregated masses which are rendered conspicuous by being surrounded by the expelled fluid which serves as a colourless background to them. The move- ments of the masses are, according to De Vries, entirely passive, and are accounted for by the currents of protoplasm, stirring them and wash- ing them to and fro.—F. D.] D 2
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