The Preparation of Permanent Stained Microscopical Specimens of Erythrocytes from Old Blood Stains

fluid. Many different fluids have been employed for this purpose, the one we prefer being Vibert's fluid (Common salt 2 grammes, Mercury Perchloride 0.5 gramme, Distilled water 100 c.c.). The clot is soaked in a few drops of Vibert's fluid in a watch glass for twenty minutes, care being taken to avoid evaporation. Then a portion of the softened clot is gently teased and transferred to a slide by means of a needle, a further drop of Vibert's fluid added, a cover glass put on. and the specimen examined under the 1112 inch objective with the diaphragm nearly closed. The cell debris must be neglected and attention focussed on the thin edge of the clot; and if the specimen is not too much contaminated with gross dirt from the original blood stain, a diagnosis as to whether non-mammalian blood is present or not can, with experience, be made in practically every