. The cytoplasm of the plant cell. Plant cells and tissues; Protoplasm. may, under some conditions, separate from the vacuolar liquid (vacuolar contraction). The large vacuole of mature cells is capable, under certain influ- ences, of losing its water and of fragmenting into minute, semi- fluid, chondriosome-shaped elements. The various aspects of the vacuolar system are, therefore, reversible and seem to depend upon the water content of the cytoplasm. Water may move into the cytoplasm and out of the vacuoles and the reverse ac- tion may take place. The vacuoles themselves, during dehydration
. The cytoplasm of the plant cell. Plant cells and tissues; Protoplasm. may, under some conditions, separate from the vacuolar liquid (vacuolar contraction). The large vacuole of mature cells is capable, under certain influ- ences, of losing its water and of fragmenting into minute, semi- fluid, chondriosome-shaped elements. The various aspects of the vacuolar system are, therefore, reversible and seem to depend upon the water content of the cytoplasm. Water may move into the cytoplasm and out of the vacuoles and the reverse ac- tion may take place. The vacuoles themselves, during dehydration of the seed, are capable of losing water to the point of being transformed into solid bodies (aleurone grains) which later, at germination, again become vacuoles after taking in water. Although in their semi-fluid state the vacuoles may very much resemble the chondriosomes and the plastids, they are always distinguishable from these elements by their histochemical behavior, notably by their instantane- ous staining with vital dyes, such as neutral red and cresyl blue, which stain neither the chondriosomes nor the plas- tids. They are to be distinguished from these elements also by the fact that the staining is essentially vital and ceases as soon as death of the cells occurs, whereupon the protoplasm is stained. This is very different from the sub- lethal staining of the chondriome which almost never occurs except in dying cells and persists after the death of the cells. Furthermore, the histochemical be- havior of the vacuoles is very variable and even the chondriosome-shaped vacuoles differ essentially from the chondriosomes, by the fact that the former have no defined characteristics. In general, they do not stain either by mito- chondrial techniques or by other methods of fixation but in all well differentiated preparations they appear as colorless canaliculi. In the case in which they are stained by mitochondrial techniques, they then appear as small vacuoles in which the
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Keywords: ., bookcentury1900, bookcollection, booksubjectplantcellsandtissues
