. Elementary botany. Botany. ABSORPTION, DIFFUSION, OSMOSE. U 33. Let us now remove some of the slices of the beet from the sugar and salt solutions, wash them with water and then im- merse them in fresh water. In the course of thirty minutes to one hour, if we examine them again, they will be found to have regained, partly or completely, their rigidity. Here again we infer from the former experiment with spirogyra that the sub- stances in the cell-sap now draw water inward ; that is, the diffusion current is inward through the cell walls and the proto- plasmic membrane, and the tissue becomes
. Elementary botany. Botany. ABSORPTION, DIFFUSION, OSMOSE. U 33. Let us now remove some of the slices of the beet from the sugar and salt solutions, wash them with water and then im- merse them in fresh water. In the course of thirty minutes to one hour, if we examine them again, they will be found to have regained, partly or completely, their rigidity. Here again we infer from the former experiment with spirogyra that the sub- stances in the cell-sap now draw water inward ; that is, the diffusion current is inward through the cell walls and the proto- plasmic membrane, and the tissue becomes turgid again. 34. Osmose in the cells of the beet.—We should now make a section of the fresh tissue of a red colored beet for examination with the microscope, and treat this section with the salt solution. Here we can see that the effect of the salt solution is to draw water out of the cell, so that the protoplasmic mem-. Fig. 23. Fig. 24. rjefore treatment with salt After treatment with salt solution. solution. Fig. 25. Later stage ot the same. Figs. 23-25.—Cells from beet treated with salt solution to show osmosis and movement of the protoplasmic membrane. brane can be seen to move inward from the cell wall just as was observed in the case of spirogyra.* Now treating the section with water and removing the salt solution, the diffusion current is in the opposite direction, that is in- * We should note that the coloring matter of the beet reside; in the cell- sap. It is in these colored cells that we can best see the movement take place, since the red color serves to differentiate well the moving mass from the cell wall. The protoplasmic membrane at several points usually clings tena- ciously so that at several places the membrane is arched strongly away from the cell wall as shown in fig. 24. While water is removed from the cell-sap, we note that the coloring matter does not escape through the protoplasmic Please note that these images are extracted from scanne
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