A Text-Book of Botany Volume 1

A Text-Book of Botany Volume 1

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1898 edition. Excerpt: ...isolated molecules or ions against the walls, it will be assumed that osmosis is due simply to the mutual attraction of small particles of solid matter and their solvents. It depends also on the molecular attraction which converts solid bodies into solutions, and which so operates that the dissolved substances become uniformly distributed throughout the solution. When two solutions of unequal concentration are separated by a membrane which is equally permeable to both, an attraction and diffusion of both liquids will take place through the separating membrajie. If, however, the membrane is more easily permeated by one of the solutions than by the other, then a larger quantity of the one than the other will pass through it; and, in case the membrane is only permeable for one solution, that one alone will be drawn through it. If a pig's bladder be filled with a solution of common salt and then immersed in water, the flow of water into the bladder is more rapid than the outflow of the salt solution, and, in consequence, an internal pressure is exerted within the bladder sufficient to expand it to a hard, rigid body. A pressure similar to that arising from the osmotic attraction of the salt solution is produced in plant cells by the substances, particularly organic and inorganic acids, salts and sugar compounds, held in solution in the cell sap. The living protoplasm of the cell does not allow any of the substances dissolved in the sap to pass out, except such as escape through the diffusion taking place between the cells themselves. In this process a constant transmutation and transformation of the cell substances occurs, but, as may be observed in cells with coloured cell sap, these are held in by the protoplasm, and in particular by the...show more

Product details

  • Paperback | 122 pages
  • 189 x 246 x 7mm | 231g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236508920
  • 9781236508928