PLASMA STAINS WITH COAL-TAR PYES. 187 



"Workers have at length found this ont, and it is now but 

 little used except for the special purposes above indicated. 



296. Ehrlich's " Triacid " Mixture.— This name would seem 

 to indicate that the mixture contains three " acid " colours, 

 which is not the case, methyl green being a strongly "basic " 

 colour. Bhrlich explains in a letter to Mayer (see also 

 Bhelich and Lazarus, Die Anspmie, 1898, p. 26) that it is 

 so called " because in it all the three basic groups of the 

 methyl green are combined with the acid dye-stuffs." A 

 very pretty conundrum ! 



The latest receipt [op. cit., p. 28) is as follows : 

 Prepare separately saturated solutions of orange G, 

 Siiurefuchsin, and methyl green, and let them clarify by 

 settling. Then mix, in the order given, using the same 

 measure-glass, 13 to 14 c.c. of the orange, 6 to 7 of the 

 Siiurefuchsin, 15 of distilled water, 15 of alcohol, 12-|- of 

 the methyl green, 10 of alcohol, and 10 of glycerin. After 

 adding the methj'l green, shake well, but do not filter. 



The mixture keeps well. I find its qualities and defects 

 to be much those of the Ehrlich-Biondi mixture. The stain 

 seems more powerful but less delicate, and the methyl green 

 in it appears to have more resistance to alcohol, so that it is 

 better adapted for ordinary work. 



Mayer (GnmdfSige, Lbb & Mayer, p. 197) has simplified the formula 

 thiis : Take 1 g. metiyl green, 2 g. orange, 3 g. Siivirefuschin, and dis- 

 solve in a mixture of 45 c.c. water, 10 c.c. glycerin, and 20 c.c. alcohol of 

 90 per cent. 



MoEEL and Doleeis (C. B. Soc. Biol, liv, 1902, p. 1255) mix 1 vol. of 

 the solution with one of 8 per cent, formalin and add 01 per cent, of 

 acetic acid, and state tliat tlius tlie methyl green is better fixed in the 

 nuclei. 



297. Pianesb's Saurefuchsin-malachite Green (from Mullee, 

 Arcli. Zellforsch., viii, 1912. p. 4) consists of 0'5 grm. malachite green, 

 O'l grm. Siiurefuchsin, and O'Ol grm. Martius yellow in 150 c.c. water 

 and 50 c.c. alcohol. Stain for 24 hours, differentiate with alcohol, con- 

 taining 1 to 2 drops of HCl per 200 c c. 



298. Piciic Acid. — Picric acid gives useful plasma stains 

 after carmine and heematoxylin. The modus (ipi^rnnrli con- 

 lists merely in adding picric acid to the alcohols employed 

 for dehydrating the objects. 



