2. Fixation in mercuric-chloride may be followed by =Ehrlich-Biondi-Heidenhain’s stain= (saturated aqueous orange 100 cc., saturated aqueous acid fuchsin 20 cc., saturated aqueous methyl green 50 cc.) 12 grms. of Grübler’s prepared stain dissolved in 100 cc. of distilled water, for stock solution. For staining take 1 cc. of stock solution, water 30 cc., ½ per cent watery acid fuchsin 3 cc., and 2 per cent acetic 5-6 drops. Stain 2-24 hours; wash in 90 per cent alcohol; dehydrate in absolute; clear in xylol; balsam. Resting nuclei are bluish; mitoses and fragments of leukocyte nuclei dark green; red blood cells orange red; protoplasm and connective-tissue fuchsin red. 3. =Benda’s Iron-Haematoxylin Method.= 1. Fix in osmic acid, mercuric chloride or other fixative. 2. Stain sections by placing them in liq. ferri. sulfur. oxyd. (Germ. Pharm.) diluted with double its volume of water, for 24 hours; wash carefully in distilled water and then in tap water; stain in 1 per cent watery hæmatoxylin until section is black. Wash in water. Differentiate in 10-30 per cent acetic acid, or in liq. ferri. sulfur. oxyd. diluted with distilled water 1-20. A 10 per cent solution of ferric sulphate may be used instead of the persulphate. 4. =Heidenhain’s Iron-Haematoxylin.= 1. Imbed in paraffin after fixation in mercuric chloride. 2. Immerse section in a 1.5 per cent solution of iron-alum sulphate (violet-colored salt) or iron-ammonium sulphate for ½-3 hours. 3. Wash in water. 4. Stain in 0.5 per cent watery hæmatoxylin or hæmatein for 12-18 hours. 5. Wash in water. 6. Differentiate in the iron-alum or iron-ammonium solution until the section becomes deep blue (control under microscope) and nuclear structures stand out distinctly. 7. Wash in running water for 15 minutes. 8. Absolute alcohol; xylol; balsam. Instead of the watery hæmatoxylin solution a mixture of hæmatoxylin 1 grm., alcohol 10 cc., and water 90 cc. may be used. Keep four weeks before using. Stain 24-36 hours. For contrast staining a weak solution of Bordeaux red may be used before the iron-alum and hæmatoxylin, staining 24 hours. =XVIII. MUCIN.= Mucin stains a deep blue or reddish-violet with an over-ripe hæmatoxylin. When counterstained with picric acid very beautiful preparations can be obtained. Mucin also gives a metachromatic reaction with kresyl-echt-violett, thionin, toluidin-blue and polychrome methylene-blue, staining red with these stains. Water or carbolic-acid solutions of these stains may be used; dehydrate in absolute alcohol, clear in xylol, and mount in balsam. In my opinion =Morse’s Carbol-kresyl-echt-violett= method as given above for amyloid is the best of these metachromatic reactions. Muchæmatein and mucicarmin give the most delicate reactions. 1. =Mayer’s Muchaematein.= 1. Absolute alcohol fixation is preferable.