Elementary practical biology vegetable / by Thomas W. Shore.

  • Shore, Thomas W.
Date:
1887
Catalogue details

Licence: Public Domain Mark

Credit: Elementary practical biology vegetable / by Thomas W. Shore. Source: Wellcome Collection.

    14/206 (page 2)
    PREPARATION OF VEGETABLE TISSUES. Vegetable Tissues may be examined either in the fresh state or after some preparation. Most of the structures required in working over the following exercises are best if they have been previoinsly kept in alcohol. This has the effect of— 1. Removing the green colouring matter, and so rendering the tissues clearer. 2. Removing any air-bubbles which may happen to be in the tissues of a plant. 3. Hardening the tissues by removing water. 4. Preserving them. It is convenient, in supplying materials for a class, to preserve in spirit plants or parts of plants which might not otherwise be obtainable when required. If it is wished to isolate the various kinds of cells which compose a tissue, it is best to macerate the part in Chlorate of Potash and Nitric Acid (Schultz’ macerating solution), which has the effect of dissolving the common cell wall and so isolating the individual cells. Sometimes it is desirable to specially harden tissues. This is done with either Chromic or Picric Acid, or with absolute Alcohol. The latter usually renders tissues brittle and difficult to cut. To obviate this, the object should be placed in Glycerin for some hours before it is cut. When Chromic or Picric Acid is employed, the object should remain in an excess of the fluid for about twenty-four hours ; should then be washed in Alcohol as long as any colour can be extracted, and finally preserved in Alcohol. IMBEDDING. In cutting sections of a small organ which cannot be conveniently held in the fingers, or which is too soft to permit of the cutting of thin sections, it is necessary to support the organ by imbedding it in some substance sufficiently large to be conveniently held, and haixl enough to enable thin sections to be cut. In such cases, it is convenient to place the object between two pieces of carrot or potato, or between two layers of dry elder-pith, and then cut sections of the imbedding substance and the object in it. Or wax, of various consistency, may be used.