CHAPTER XVI 

 PLASMA STAINS * WITH COAL-TAR DYES 



318. Introduction. By a plasma stain is meant one that stains 

 the extra-nuclear parts of cells and the formed material of tissues, 

 or one of these. 



The plasma stains described in this chapter are for the most 

 part those obtained by means of " acid " dyes (§ 237) ,• but 

 some of them are obtained by means of " neutral " dyes (§ 237), 

 and a few by " basic " dyes. 



The mode of staining is generally progressive, almost always so 

 when acid colours, used substantively, are employed. But 

 the regressive method, with differentiation, is sometimes made 

 use of, especially when a mordant has been used with the dye. 



In some processes, e.g. Flemming's orange method, a basic 

 and an acid dye (or vice versa) being employed in succession, 

 there is formed iyi the tissues a neutral colour (§ 237) which effects 

 the desired stain. These may be considered as adjective stains, 

 the first colour serving as a mordant for the second. Not any 

 two dyes taken at haphazard will behave in this way : they 

 must be such as to form by combination a suitable neutral lake 

 {cf. § 237). The basic dye may be made the primary stain, as in 

 Flemming's process : or the contrary. 



In such stains as Reinke's orange method, or the Ehrlich- 

 Biondi mixture, and many others, one or more neutral colours 

 are formed in the mixture and stain progressively. 



Excepting Biebrich scarlet, we are not acquainted with any 

 plasma stain that is thoroughly satisfactory for delicate work. 

 In addition to Biebrich scarlet, we recommend for sections 

 Saurefuchsin, either alone or in the form of Ehrlich-Biondi 

 mixture, or Ehrlich's triacid : for material in bulk, picric acid 

 (but only for rough work). 



319. Saurefuchsin (Acid Fuchsin, Fuchsin S, Acid Rubin, Rubin 

 S, Saurerubin, Acid Magenta, Magenta S). This must not be 



* This chapter includes only such stains as are used in ordinary work 

 on tissues in bulk or sections, stains for special purposes being treated 

 under " Nervous tissue," " Blood," etc. It includes some double or 

 triple stains that colour nuclei as well as plasma, but in different hues. 

 Refer to the British dye index of the Society of Dyers and Colourists 

 (1923) or Schultz's " Farbstofftabellen " (192.3). For most purposes 

 Dr. H. J. Conn's book, " Biological Stains " (1936) will give all informa- 

 tion needed. 



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