. The cytoplasm of the plant cell. Plant cells and tissues; Protoplasm. Guilliermond - Atkinson — 184 Cytoplasm to be attributable to the viscosity of their contents, since the co- existing vacuoles without colloidal substances are always spherical. In all cases in which the cells contain two categories of vacu- oles, these vacuoles become distinct very early and it is very diffi- cult to determine their origin. It would seem, however, that the vacuoles lacking in colloidal substances arise by exudation from vacuoles rich in colloids, for, by plasmolysis, it is possible in some cases to obtain
. The cytoplasm of the plant cell. Plant cells and tissues; Protoplasm. Guilliermond - Atkinson — 184 Cytoplasm to be attributable to the viscosity of their contents, since the co- existing vacuoles without colloidal substances are always spherical. In all cases in which the cells contain two categories of vacu- oles, these vacuoles become distinct very early and it is very diffi- cult to determine their origin. It would seem, however, that the vacuoles lacking in colloidal substances arise by exudation from vacuoles rich in colloids, for, by plasmolysis, it is possible in some cases to obtain experimentally the formation of similar small vacu- oles in cells which do not contain any. It would be natural, therefore, along with Weber and Kuster, to relate this phenomenon to vacuolar contraction and to attribute it to a syneresis assuming that the vacuoles not staining with vital dyes are totally lacking in colloidal substances. But we have seen that this is not always so and in the fruit of the blackberry there exist two categories of vacuoles both of which contain colloidal substances. In this case it might be supposed that these two categories of vacuoles, which seem to correspond to small accumulation and transportation centers for various meta- bolic products, are always distinct and have no genetical connection, or else that they arise by a differentiation from a single category of vacuoles, but by the phenomenon of coacervation and not of syneresis (Cf. p. 177). However this may be, this last ex- planation does not apply to the lower plants, in particular to the algae, in which there are encountered still more fre- quently, several categories of vacuoles in a single cell. In the brown algae it has been known for a long time that there exist viscous inclusions which have been called fucosan granules (Hansteen), or phy- sodes (Crato), whose morphological sig- nificance has been the subject of numerous discussions. These inclusions stain vitally like the vacuoles
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