. Principles of the anatomy and physiology of the vegetable cell. Plant cells and tissues. THE VEGETABLE CELL. 45 by Fritzsche in " Poggend, ; part 32; of Payen in ''Mem. sur les Develojypements des Vcgetaux^'" and of Schleiden in. his " Grundzhge!') The starch granules of different shape agree in the circumstance that they are not composed of one uni- ^'^iJ- ^^• form mass, hut of super-imposed layers of varying density, whence they derive a pretty appearance with polarized light, each granule exhibiting a coloured cross. These layers are usually much thicker on one sid
. Principles of the anatomy and physiology of the vegetable cell. Plant cells and tissues. THE VEGETABLE CELL. 45 by Fritzsche in " Poggend, ; part 32; of Payen in ''Mem. sur les Develojypements des Vcgetaux^'" and of Schleiden in. his " Grundzhge!') The starch granules of different shape agree in the circumstance that they are not composed of one uni- ^'^iJ- ^^• form mass, hut of super-imposed layers of varying density, whence they derive a pretty appearance with polarized light, each granule exhibiting a coloured cross. These layers are usually much thicker on one side of the granule than on the other (fig. 4i6), so that the organic centre is far removed from the middle point, and often closely approximated to the surface. In fresh granules there is no cavity in the centre, but ^*^the fSato! ^^ one is readily produced by dessication and by the contraction this produces of the internal softer substances. This process may be traced very beautifully under the microscope, by removing a part of the water, by strong alcohol, from fresh starch granules taken from the Potato. In this case a little globular cavity is first formed, and then radiating fissures soon run out in all directions, traversing the layers of the granule at right angles. This undoubtedly results from the middle layers being softer, and more swollen up by water than the outer. But the firmness is still so great that the starch granules may be broken up into angular pieces by pressure. Cold water does not exert any sol- vent power over them, even when the granules are cut into thin slices, so as to allow the water to come immediately in contact with their inner layers. In boiling water they swell very much, even a hundred times their original volume, without actual solu- tion. The same effect is produced by the action of strong acids and caustic alkalies. When iodine and water act simultaneously either in the swollen or unswoUen granules, these are coloured, according to the am
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectplantcellsandtissues
