A course of practical histology / by Edward Albert Schäfer.

  • Sharpey-Schäfer, E. A. (Edward Albert), Sir, 1850-1935.
Date:
1897
Catalogue details

Licence: Public Domain Mark

Credit: A course of practical histology / by Edward Albert Schäfer. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

    34/320 (page 16)
    in a few days. For use as a dissociant the solution may be diluted down to 0-05 per cent. (J^ per cent.) or more. Bichromates.—Bichromate of potash and bichromate of ammonia are both used extensively in histology, in solutions of 2 per cent, to 3 per cent. They have the advantage over chromic acid that they penetrate a piece of tissue more rapidly, so that larger portions of organs can be hardened in them, and they interfere less than the acid with the subsequent staining by dyes. But they do not preserve the minute structure of the tissues, at least of their cells and nuclei, as do solutions of chromic acid ; nor is the hardening process so rapid (2 to 4 weeks). Muller's fluid is a 2^ per cent, solution of bichromate of potash in water containing 1 per cent, of sulphate of soda. Osmic acid.—This is the most rapid fixative for most tissues, and in some respects the most perfect, for it usually kills protoplasmic structures so suddenly that there is no time for any contraction or other change of form to occur. On this account it is extensively used, alone and combined with other reagents. But it has the disadvantage that, more than most other fixatives, it interferes with the subsequent staining of cells by dyes ; nor does it bring out the fine structure of cells and nuclei as well as chromic or picric acid. It stains sub- stances of a fatty nature black. It is usually allowed to act on a tissue only for a short time (15 minutes to 3 hours). It is conveniently kept as a 1 per cent, or 2 per cent, solution. Acetic acid.—This is rarely used alone as a fixative, but has been a good deal employed in combination with other reagents. Acetic acid is also useful for determining the action of weak acids upon the tissues. For this purpose it may be kept in 1 per cent, solution. Flemming's fluid is constituted as follows :— Osmic acid, 2 per cent. . . 4 parts Chromic acid, 1 per cent. . . 15 „ Glacial acetic acid . . . 1 „ Hermann's fluid has a similar composition, but with 1 per cent, platinic chloride substituted for the chromic acid.