132 Biological Stains 



Amethyst violet has been used by EhrHch and Lazarus (1898) as a 

 basic dye in certain triple staining technics. 



A further dye of this group which the biologist must take into 

 account, although probably of no significance as a stain, is methy- 

 lene violet RRA or 3RA, C.I. No. 842 (syn. : fuchsia or safranin 

 extra bluish) . This dye is a di-methyl safranin in which the methyl 

 groups are introduced into one of the amino groups instead of 

 directly into the benzene ring. It has no connection with the 

 methylene violet of Bernthsen, which is one of the constituents of 

 polychrome methylene blue; see p. 114. A sample has been found 

 labelled ''Safranin, pur", Grubler. 



l30 azocarmine g c. I. NO. 8i8 



Synonyms: Azocarmine GX. Rosazine. Rosinduline GXF. 

 The sodium salt of a disulfonic acid of phenylrosinduline : 



C28H20N3CI; Mol. Wt. 433.921 

 {An acid dye; absorption maxima about 512) 



A spectral curve for this dye, together with one for neutral red, 

 is given in Fig. 15, p. 127. 



This dye is occasionally employed in tissue staining, notably 

 after M. Heidenhain (1915) who used it as a tissue stain either 

 alone or preceding some nuclear stain. Heidenhain gave sj>ecial 

 attention to its use in the Mallory anilin blue connective tissue 

 stain; in which procedure he employed it in place of acid fuchsin 

 in the Mallory technic. This azocarmine modification of the 

 Mallory stain is very commonly followed according to the schedule 

 given by McGregor (1929) which calls for staining in azocarmine, 

 differentiation in anilin alcohol, then treatment in 5% phospho- 

 tungstic acid before application of the Mallory anilin-blue-orange- 

 G mixture. (Unfortunately McGregor calls the dye ''azan car- 

 mine".) Another modification is that of Volkmann and Strauss 

 (1934) who used azocarmine after a resorcin gentian violet. 



There is a closely related dye, azocarmine B (C. I. No. 829) 

 which is a trisulfonate instead of a disulfonate. Heidenhain em- 



