Bacilli deep-blue; tissues light-blue. 15. =Bacillus of Rhinoscleroma.= Gram-positive. Fix in alcohol for _Wolkowitsch’s method_:— 1. Stain in aniline gentian-violet 24-48 hours. 2. Wash in water. 3. Treat with Lugol’s 1-4 minutes. 4. Decolorize in absolute alcohol. 5. Remove more color by oil of cloves. 6. Xylol; balsam. In tissues fixed in osmic acid and then stained in hæmatoxylin the bacilli are dark blue with light blue capsules. The hyaline substance of rhinoscleroma stains with basic stains. 16. =Friedländer’s Bacillus.= Gram-negative. Stains with ordinary aniline dyes. For staining the capsules the following method is advised:— 1. Stain for 24 hours in the incubator in a mixture of a concentrated alcoholic solution of gentian-violet 50 cc., glacial acetic acid 10 cc., and distilled water 100 cc. 2. Wash in a 1 per cent acetic acid solution. 3. Alcohol; xylol; balsam. Bacilli deep-blue; capsules light-blue. 17. =Tubercle-bacillus.= Gram-positive. Stain in sections on warm carbol-fuchsin without removing paraffin, as given above. Alcohol and mercuric chloride fixation give best results. Aniline-gentian-violet may also be used, staining with a warm solution for 15-30 minutes, and decolorizing in 20 per cent nitric acid followed by 70 per cent alcohol, counterstaining in Bismarck brown, dehydrating in alcohol, clearing in xylol and mounting in balsam. The Weigert-Gram method may be used for the demonstration of the branched or streptothrix forms of the tubercle bacillus. For celloidin sections _Mallory and Wright_ advise the following:— 1. Stain rather lightly in alum-hæmatoxylin. 2. Wash in water. 3. Dehydrate in 95 per cent alcohol. 4. Attach sections to slide by ether-vapor method. 5. Stain in steaming carbol-fuchsin 2-5 minutes. 6. Wash in water. 7. Acid alcohol ½-1 minute. 8. Wash thoroughly in several changes of water to remove acid completely and to bring back blue color to nuclei. 9. 95 per cent alcohol to remove fuchsin. 10. Aniline-oil, followed by xylol, blotting. 11. Xylol; balsam. Celloidin is colorless, nuclei blue, tissue colorless, tubercle-bacilli red. Orange G may be used as a diffuse stain. 18. =Lepra Bacillus.= Gram-positive. Stain paraffin sections on warm carbol-fuchsin, as for the tubercle-bacillus. To differentiate from the tubercle-bacillus, stain 6-7 minutes in a dilute alcoholic solution of fuchsin, and decolorize in acid alcohol (nitric acid 1, alcohol 10). Lepra-bacilli stain; tubercle-bacilli do not. _c. Trichomycetes._