172 clIAPTIiii XIV. 



intense violet ; Lut this, as pointed out by Squire [Methods and Formulie, 

 etc., Churchill, 1892. p. o7), is undoubtedly 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 (Wbigert, in 

 Arch. mili. Anat., xv, 1878, p. 258). You may add a little 

 acetic or osmic acid to the solution. M.4.YSEL [ibid., xviii, 

 1830, pp. 237, 250) dissolves the colour in acetic acid (this 

 solution does not give a |)ermanent stain). Alcoholic solu- 

 tions may also be used, e. cj. saturated aqueous solution 

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

 Calbekla's glycerin-and-alcohol- mixture, or dilute glycerin 

 (say of 40 per cent, to 50 per cent.) may very advan- 

 tageously be employed. 



The watery solutions must be frequently filtered (but then 

 much of the colour is retained on the filter) . The addition 

 to them of carbolic acid has been recommended (vide Juurn. 

 Roy. Mic. Soc, 18S6, p. 908). Bismarck brown stains rapidly, 

 but never overstains. The stain is permanent both in balsam 

 and in glycerin. 



This colour may be used as a chromatin stain for fresh 

 tissues in the same way as methyl green. Heela {Arch. Binl., 

 xiii, 1893, p. 423) employs for ova of Ascaris a mixture of 

 0'25 parts vesuvin, 0'25 malachite green, 10 of glycerin and 

 100 of water, and washes out with weak glycerin. 



The chief use of this colour is lor progressive staining ; 

 but it may be employed for staining by the regressive method 

 (see § 289), and also for Intva-vUam staining (§ 208) (for 

 this purpose it is necessary to see that the colour employed 

 be pure and neutral). 



278. Methyl Violet (Methylanilin Violet, Anilin Violet, Paris 

 Violet). — Geaseb {Deutsche Zeit. Chirurgie, xxvii, 1888. pp. -538 — 584; 

 Zeit. wiss. Mile, y, 3, 1888, p. 378) stains sections from twelve to twenty- 

 four hours in a solution so dilute that at the end of that time the 

 sections will have taken up all the colour from the liquid. They are 

 then washed out for a short time in acidulated alcohol, and then in pm-e 

 alcohol. The method is applicable to objects fixed in Flemming's 

 mixture. 



