Biology Pamphlets Volume 1566

Biology Pamphlets Volume 1566

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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. 1914 edition. Excerpt: ...are any such pores in a root we should expect that they might be revealed by the sap leaking out through them when the surface of the root is wiped dry and gentle pressure applied as in the experiment with soaked beans. Is any leakage perceptible in an uninjured root thus treated; and if so, where?--II. Can water pass through a layer or membrane of cellulose which does not leak? Obtain some parchment paper or, better, a diffusion shell.1 (Both of these are made of paper-pulp so treated, usually with sulphuric acid, as to form a continuous membrane without interstices between the fibers. Test a small bit of it for cellulose.) If the parchment paper is to be used, moisten 1 Schleicher & Schull's Diffusion Shells, 100x16 mm. are sold by dealers i chemical supplies. a piece with water, and tie it firmly with waxed thread over the mouth of a thistle tube. If a diffusion shell is preferred, attach it similarly to a short tube of suitable diameter such as a test tube opened by melting off the lower end, and insert in the other end a perforated rubber stopper through which passes a tube of small caliber one or two feet long. Now fill the apparatus with water, and notice whether there is any leakage or filtering of the water through or around the membrane; and if so, make the fastening tighter, or if necessary try another piece of paper or another shell till you are sure there is no leak. Then in place of the water in the tube put in several spoonfuls of beet juice obtained by grating some beets and squeezing the pulp in a cloth. Finally arrange the tube in a vessel of water as shown in Fig. XII. Begin with the two liquids at the same level. When the test-tube arrangement is used it is well to have the liquids come at least to LJQ the rubber more

Product details

  • Paperback | 32 pages
  • 189 x 246 x 2mm | 77g
  • United States
  • English
  • black & white illustrations
  • 1236499719
  • 9781236499714