PLA.SMA STAINS WITH COAL-TAR nVKS. 185 



fuchsin should be " Rubin S " (" Rubin " is a synonym of 

 Fuchsin) and the methyl green should be " Methylgriin 00." 

 And it is absolutely necessary that these ingredients be those 

 prepared under those names by the Actienfahrik fiir Anilin- 

 fahrikation in Berlin. They can be obtained from Griibler 

 & Hollborn, either separately, or as a mixture of the three 

 dyes in powder (which. I do not recommend). 



'J.^he strong solutions directed to be taken readily precipi- 

 tate on being mixed. To avoid this it is recommended by 

 Squikb [Methods and Formulae, etc., p. 37) to dilute them 

 before mixing. 



Other proportions for the mixture have been recommended by Kratjsb 

 (loc. cit. supra), viz. 4 c.c. of the Sfiurefuohsin solution, 7 of the orange G 

 and 8 of the methyl green ; the mixture to be diluted 50 to 100-fold with 

 water. Thome {Arch. mile. Aiiat., lii, 1898, p. 820) gives the proportion.? 

 2:6:8, and dilutes 100-fold. 



Stain sections (N.B. sections only) for six to twenty-four 

 hours. Dehydrate with alcohol, clear with xylol, and mount 

 in xylol balsam. 



In the intention of the observers who have elaborated this 

 stain it is a progressive stain, and not a regressive one. It 

 does not require any differentiation, and the sections should 

 be got through the alcohol into xylol as quickly as possible 

 in order to avoid any extraction of the methyl green, which 

 easily comes away in the alcohol. Drijnee {Jena. Zeit., 

 xxix, 1894, p. 276) stains for ten minutes in the concentrated 

 solution, treats for one minute with, alcohol containing O'l 

 per cent, of hydrochloric acid, and then with neutral 

 alcohol. 



The best results are obtained with sublimate material; 

 chrom-osmium material, and the like, give a much inferior 

 stain. Preparations made with the usual mixture, as given 

 above, are liable to fade; by acidifying the mixture a 

 stronger and more sharply selective stain is obtained, which 

 does not fade. But too much acid must not be added, 

 as this would cause a staining of the interfilar substances. 

 According to the Encycl. iiiik. Tcrhnih, you may add 15 

 to 24 drops of 0-2 per cent, acetic acid to 100 c.c. of the 

 diluted solution. 



Another process of acidification is given by M. Hbidenhain [TJcher 



