COAL-TAR PLASMA STAINS. 215 



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

 Rubin S, Saurerubin, Acid Magenta, Magenta S). The chemical 

 description of this acid colour has been given ( 262) : it is 

 important not to confound it with basic fuchsin, as seems to 

 have been done by some writers. 



This is one of the best cytoplasm stains that I know of. 

 I use a 0*5 per cent, solution in water, and allow it to act on 

 sections for a few minutes. The stain is sufficiently resistent 

 to alcohol. Saurefuchsin is also used as a specific stain for 

 nerve tissue (see " Neurological Methods " in Part II). 



288. Saurefuchsin and Orange G. I have had good results by 

 mixing the aqueous solutions of these two dyes, but unfor- 

 tunately have not noted the proportions. 



289. VAN GIBSON'S Picro-Saurefuchsin (from Zeit. f. wiss. 

 Mik.j xiii, 3, 1896, p. 344). To a saturated aqueous solution 

 of Saurefuchsin is added a few drops of saturated aqueous 

 solution of picric sicicl, until the mixture has become garnet- 

 red. After staining, rinse with water, dehydrate, and clear 

 in oil of origanum. According to MOLLEU (op. cit., xv, 2, 

 1898, p. 174), a good formula, due to WEIGERT, is warm 

 saturated picric acid solution, 150 c.c. ; saturated Saure- 

 fuchsin solution, 3 c.c. 



OHLMACBER (Journ. Exper. Hed., ii, 1897, p. 675) adds 0'5 

 per cent, of Saurefuchsin to a saturated solution of picric 

 acid which has been diluted with an equal quantity of water. 

 He uses this after previous staining with gentian violet. 



290. The EHRLICH-BIONDI Mixture (or EHRLICH-BIONDI-HEI- 

 DENHAIX Mixture) (Pfl tiger's Arch., xlii, 1888, p. 1 ; Zeit. f. 

 ?'-/.sx. A/7/\, v, 4, 1888, p. 520). This well-known stain is 

 somewhat troublesome to prepare. It may be obtained ready 

 made from Griibler & Hollborn. 



The receipt is as follows : To 100 c.c. saturated aqueous 

 solution of orange add with continual agitation 20 c.c. 

 saturated aqueous solution of Saurefuchsin (Acid Fuchsin) 

 and oO c.c. of a like solution of methyl green. 



(According to Krause [Arch. mik. Anal., xlii, 1893, p. 59], 100 parts of 

 water will dissolve about 20 of Saurefuchsin [Rubin S], 8 of orange G ; 

 and 8 of methyl green.) The solutions must be absolutely saturated, 

 which only happens after several days. 



