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.