CHAPTER XIV. 161 



Staining is instantaneous ; overstating never occurs. The 

 solution is very penetrating, kills cells instantly without swelling or 

 other change of form, and preserves their forms for at least some 

 hours, so that it may be considered as a delicate fixative. It may 

 be combined without precipitating with divers fixing or preserving 

 agents. Osmic acid (of 0-1 to 1 per cent.) may be added to it, or it 

 may be combined with solution of BIPART and PETIT (this is an 

 excellent medium for washing out 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 satis- 

 factorily 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-BIONDI combination), considerably increased by treating 

 the sections for a few minutes with tincture of iodine before staining 

 (M. HEIDENHAIN). 



Of preparations mounted with excess of colour in the usual 

 aqueous media, I find the most fortunate only survive for a few 

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

 in BRUN'S glucose medium. 



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 CURSCHMANN 

 ( Virchow's Arch., vol. Ixxix, 1880, p. 556), who showed that it colours 

 amyloid substance of an intense violet ; but this, as pointed out by 

 SQUIRE (Methods and Formula, etc., Churchill, 1892, p. 37), is un- 

 doubtedly due to its containing methyl violet as an impurity. 



277. Bismarck Brown (Manchester Brown, Phenylen Brown, 

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

 work either with fresh tissues or with such as have been hardened 

 in chromic acid, or otherwise. 



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

 in water, and filter after a day or two (WEIGERT, in Arch. mik. 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 does not give a permanent stain). 

 Alcoholic solutions may also be used, e.g. saturated aqueous solution 

 diluted with one-third volume of 90 per cent, alcoholic ; or CAL- 

 BERLA'S glycerin-and-alcohol mixture or dilute glycerin (say of 

 40 per cent, to 50 per cent.) may very advantageously be employed. 



The watery solutions must be frequently filtered (but then much 



M. 11 



