. Cytological technique; the principles underlying routine methods. Histology -- Technique; Cytology -- Technique. occurs in purpurine but not in alizarine, is rather unreactive, and the two dyes tend to behave similarly with mordants. ^^^ Both dyes occur naturally in the form of glucosides in the root of the madder plant, Rubia tinctonim (Rubiaceae), but the synthetic products are almost invariably used. Purpurine is unfortunately named, for it is a red dye. If purpurine is dissolved at saturation in 60 °o ethanol, it acts as a typical though very weak acid dye. This can be shown by carry- in
. Cytological technique; the principles underlying routine methods. Histology -- Technique; Cytology -- Technique. occurs in purpurine but not in alizarine, is rather unreactive, and the two dyes tend to behave similarly with mordants. ^^^ Both dyes occur naturally in the form of glucosides in the root of the madder plant, Rubia tinctonim (Rubiaceae), but the synthetic products are almost invariably used. Purpurine is unfortunately named, for it is a red dye. If purpurine is dissolved at saturation in 60 °o ethanol, it acts as a typical though very weak acid dye. This can be shown by carry- ing out the tests described on p. 101. If, however, the dye is dis- solved in a solution of aluminium sulphate, the result is entirely different. The following is a convenient solution. Take 0-8 g of purpurine and 7-88 g of aluminium sulphate crystals (I6H2O); add 450 ml of 60°o ethanol; boil with reflux condenser until the solids have dissolved; cool; make up to 500 ml with 60°0 ^ The purpurine in this solution, if pure, is at M/160, the aluminium sulphate at M/40. The solution may be called stand- ard aluminium purpurine, or 'purpural' for short. The ethanol in this solution increases the solubility of the dye and thus makes the solution last longer when used repeatedly; it slows down or prevents the growth of bacteria and moulds; and it decreases ionization and thus 'equalizes' the action on tissues (that is to say, prevents the solution from over-dyeing locally).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Baker, John Randal, 1900-. London, Methuen; New York, Wiley
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