. The cell; outlines of general anatomy and physiology. at is to say, its molecules must becomedeposited between the plasmic particles, and from there be trans-ferred to the interior. Further, a substance in solution can, even ifit be not actually absorbed, produce an osmotic action by exertingan attraction upon the water contained in the cell, and by thus THE VITAL PROPERTIES OF THE CELL 130 inducing a flow of water towards the exterior. Essentiallyosmosis consists in this, that two fluids simultaneously passthrough a membrane in opposite directions ; with regard to anendosmotic equivalent (a
. The cell; outlines of general anatomy and physiology. at is to say, its molecules must becomedeposited between the plasmic particles, and from there be trans-ferred to the interior. Further, a substance in solution can, even ifit be not actually absorbed, produce an osmotic action by exertingan attraction upon the water contained in the cell, and by thus THE VITAL PROPERTIES OF THE CELL 130 inducing a flow of water towards the exterior. Essentiallyosmosis consists in this, that two fluids simultaneously passthrough a membrane in opposite directions ; with regard to anendosmotic equivalent (a term expressing the proportionate inter-change, upon which there is frequently too much stress laid), thiscannot be spoken of in such cases where only water is diosmosedthrough a membrane (Pfeffer V. 23). On account of their fragility and small size, experiments uponosmosis can only be made in animal cells with great the osmotic processes have been investigated chiefly bybotanists in plant cells, which are much more suitable, and our. Fig. 59.—1. A young, at most half-grown, cell from the cortical parenchyma of the flowerpeduncle of Cephalaria leucantha. 2. The same cell immersed in a 4 per cent, solution. same cell in a 6 per cent, solution. 4. The same cell in a 10 per cent, solution (Nos. 1and 4 are taken from nature, Nos. 2 and 3 are diagrammatic ; all in optical longitudinalsection). 7i Peripheral layer ; p protoplasmic coating of wall; 7c nucleus; c chlorophyllgranules; s cell sap; e salt solution which has penetrated into the interior. After deVries (V. 36). knowledge has been especially advanced by the following experi-ments. If plant cells containing a large sap space are placed in a 5 to20 per cent, solution of a suitable salt, or of sugar or glucose(Fig. 59), they are seen to diminish somewhat in size from havinggiven up water from the interior to the exterior; in consequence,as this process of water abstraction proceeds, the protoplasmiccoa
Size: 2244px × 1114px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookidcelloutlines, bookyear1895
