The microscope and its revelations / by William B. Carpenter.

  • Carpenter, William Benjamin, 1813-1885.
Date:
1868
Catalogue details

Licence: Public Domain Mark

Credit: The microscope and its revelations / by William B. Carpenter. Source: Wellcome Collection.

    245/882 (page 199)
    allowed to cool. After the lapse of an hour, much of the excess of ammonia will have escaped; and the solution is then to be mixed with 2 oz. of Distilled Water, 2 oz. of pure Glycerine, and \ oz. of Alcohol. The whole may be passed through a filter ; or, after being allowed to stand for some time, the perfectly clear supernatant fluid may be poured off and kept for use. If, after a long keeping, a little of the Carmine should be deposited through the escape of the ammonia, the addition of a drop or two of Liquor Ammonia; will re-dissolve it. The most valuable result of this process is the facility with which, when carefully and judiciously employed, it enables the Microscopist to distinguish what Dr. Beale terms ‘germinal matter,’—which is identical with the ‘ protoplasm ’ or ‘ sarcode ’ of other Physiologists—from the ‘ formed materials ’ or tissue-elements,which are the products of its activity ; the living formative substance being stained by Carmine so much sooner than any of those products, that it may be deeply dyed whilst they remain colourless. “The rapidity,” says Dr. Beale, “with which the colouring of a tissue immersed in this fluid takes place, depends partly upon the character of the tissue, and partly upon the excess of ammonia present in the solution. If the solution be very alkaline, the colouring will be too intense, and much of the soft tissue or imperfectly developed formed mate- rial around the germinal matter is destroyed by the action of the alkali. If, on the other hand, the reaction of the solution be neutral, the uniform staining of tissue and germinal matter may result, and the appearances from which so much may be learned are not always produced. When the vessels are injected with the Prussian blue fluid, the Carmine fluid requires to be sufficiently alkaline to neutralize the free acid present. The permeating power of the solution is easily increased by the addition of a little more water and alcohol. In some cases the fluid must be diluted with water, alcohol, or glycerine; and the observer must not hastily condemn the process, or conclude (as some have) that a particular form of germinal matter is not to be coloured, until he has given the plan a fair trial, and tried a few experiments.”* Of the special uses of this method, various illustrations will be given hereafter. 146. Preparation of Specimens in Viscid Media.—To Dr. Beale the Microscopist is also indebted for a method of pre- paring Animal and Vegetable tissues for examination under the l-12th, l-20th, or l-25th-inch Objectives, which is much supe- rior to those in ordinary use. This consists in the substitution of a viscid medium, such as pure Glycerine or strong Syrup, for the Aqueous fluids with which the object to be examined is usually treated ; many advantages being thereby gained. Thus in thin- ning-out tissues by compression, an amount of pressure may be * “ How to Work with the Microscope,” 4th edit. p. 109.