210 CHAPTEE XV. 



tive. It may be combined without precipitating with divers 

 fixing or preserving agents. Osmic acid (O'l to 1 per cent.) 

 may be added to it, or it may be combined with solution of 

 RIPART and PETIT (this, by the way, is an excellent medium 

 for washing out in and mounting in). 



Alcoholic solutions may also be used for staining. They 

 also should be acidulated with acetic acid. 



The stain does not keep easily. It is difficult to mount it 

 satisfactorily in balsam, because the colour does not resist 

 alcohol sufficiently (unless this be charged with the colour). 

 The resistance of the colour to alcohol is, however (at all 

 events if it be used in the EHRLICH-BIONDF combination), con- 

 siderably increased by treating the sections for a few minutes 

 with tincture of iodine before staining (M. HEIDENHAIN). 

 And SQUIRE declares that thorough washing with water 

 before passing into the alcohol has the same effect. 



Of preparations mounted with excess of colour in the usual 

 aqueous media the most fortunate only survive for a few 

 months. Dr. HENNEGUY, however, writes to me that it keeps 

 well in B RUN'S glucose medium. 



Undoubtedly methyl green is one of the most valuable 

 stains yet known. It is the classical chromatin stain for fresli 

 tissues. 



It was first pointed out, I believe, by HESCHL (Wiener med. Wochenschr., 

 ~2, 1879), that methyl green is a reagent for amyloid degeneration. His 

 observations were confirmed by CUESCHMANN (Vircliow's Arch , vol. Ixxix, 

 1880, p. 5o(.5), who showed that it colours amyloid substance of an intense 

 violet; but this (as pointed out by SQUIRE, Methods and Formulx, etc., 

 Churchill, 1892, p. 37) is undoubtedly due to its containing methyl violet 

 as an impurity. 



278. Bismarck Brown (Manchester Brown, Phenylen Brown, 

 Vesuvin, La Phenicienne). A fairly pure nuclear stain that 

 will \\nrk either with fresh tissues or with such as have been 

 hardened in chromic acid. 



The colour is not very easily soluble in water. You may 

 boil it in water, ;md filter after a day or two (WEIGERT, in 

 Arch. f. in IL-. Anat., xv, 1878, p. 258). You may add a little 

 acetic or osmic acid to the solution. MAYSEL (ibid., xviii, 

 1880, pp. 237, 250) dissolves the colour in acetic acid (this 

 solution dues not give a permanent stain). Alcoholic solu- 



