Percy L. Johnson

THE GRAM STAINING MECHANISM OF CAT TONGUE KERATIN

Ermsst’s early observation (4) that keratin staimis positively with Gramn’s muethod led us to apply the staimi to the keratogemsous zomies of epithelial structures, and subsequemitly to attempt a cytochemical analysis of the mechanism of the staimi. Our studies of the keratin of cat tongue filiform papillae, although not yet completed, failed to comsfirrn the recemit claims by Fischer and Larose (5) that sulfhydryl groups participate in the staims. It was evident, however, that certain reactive groups of proteimis are involved.

The Gram staining mechanism of cat tongue keratin. II. The role of potassium iodide-iodine solution.

The aniline-xylene decolorizer of the Gram-Weigert staining procedure failed to remove crystal violet dye from stained sections of cat tongue without prior treatment of the sections with potassium iodide-iodine solution. The potassium iodide of the iodide-iodine solution was found to release the major part of the crystal violet dye bound by the tongue sections. Iodine appeared also to play a role in dye release, but only to a slight degree. The amount of Gram-positive staining was increased both by alkaline treatment of the tissue prior to staining, and by increasing the pH of the iodide-iodine solution.