The microtomist's vade-mecum : a handbook of the methods of microscopic anatomy.

  • Lee, Arthur Bolles, 1849-1927.
Date:
1890
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Licence: Public Domain Mark

Credit: The microtomist's vade-mecum : a handbook of the methods of microscopic anatomy. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    damar. Or they may be stained, washed, dehydrated, and cleared in watch-glasses, and afterwards mounted as desired —the imbedding medium being first removed if desirable. It is not always desirable to remove the imbedding mass ; celloidin sec- tions stain well without being freed from it, and are usually even dehydrated, cleared, and mounted without removal of the mass, which becomes quite transparent in balsam. This plan has the advantage, which is a very impor- tant one for lai'ge sections, of allowing the sections to remain during the whole of the manipulations protected by a supportiag mass that holds all ■ their parts together. The plan of staining sections on the slide is of somewhat recent introduc- tion; before it had been worked out the practice was to stain structures in toto, before cutting sections. And in cases in which structures are suffi- ciently small and permeable to allow of satisfactory staining in this way, and if it be not essential to save time, this plan is sometimes as good as the one described. In this case the object, after having been fixed and washed out, is taken from the water, or while still on its way through the lower alcohols (it should not be allowed to proceed to the higher grades of alcohol before staining, if that can be avoided), and passed through a bath of stain (gene- rally alcoholic borax-carmine or other alcoholic stain) of sufficient duration, then dehydrated with successive alcohols, passed throu_gli a clearing medium into paraffin, cut, and treated as above described, the sections in this case being mounted direct from the turpentine, naphtha, or other solvent with which the paraffin is removed. If aqueous staining media be employed (and it is sometimes very desirable for particular purposes to prepare specimens with some aqueous stain) the structures should either be stained in toto immediately after fixing and washing out, or sections may be stained on the slide, the objects being passed through successive baths of alcohol of gradu- ally decreasing strength before being put into the aqueous stain (a precaution which will not be necessary for chromic objects (see below, § 5)). It was stated in the first edition of this work that the great majority of preparations are made by fixing either with subli- mate or a pici'ic acid combination, washing out with alcohol, staining with alcoholic borax-carmine, imbedding in chloro- form-paraffin, cutting with a sliding microtome, and mounting the sections in series in Canada balsam. That is probably still the case, but the method can no longer claim to be Avhat it then appeared to be, the classical method of microscopic anatomy. I suggest the following, as being quite as easy to carry out, and as giving preparations far richer in detail and more truthfully preserved :—Fix in Flemming's chromo-aceto- osmic mixture ; wash out with water ; dehydrate; clear with oil of cedar-wood ; imbed in paraflSin; mount sections on the slide with Mayer's albumen medium; stain with safranin, or