216 CHAPTER XVI. 



Dilute the mixture with 60 to 100 volumes of water. The 

 dilute solution ought to redden if acetic acid be added to 

 it ; and if a drop be placed on blotting-paper it should form 

 a spot bluish green in the centre, orange at the periphery. 

 If the orange zone is surrounded by a broader red zone, the 

 mixture contains too much fuchsin. 



According to M. HEIDENHAIN'S instructions (" Ueber Kern 

 u. Protoplasma/' in Festschr. Herrn. Geli. A. v. Kolliker 

 gewidm., etc., 1892, p. 115; Zeit. f. wixs. Mik., ix, 2, 1892, 

 p. 202) the orange to be used should be " Orange G ; '' the 

 Acid Fuchsin or Saurefuchsiii should be f ' 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 Actienfdbrik fiir Anilin fabrication 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). 



The strong solutions directed to be taken readily precipi- 

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

 SQUIKE (Method* and Formula, etc., p. 37) to dilute them 

 before mixing. 



Other proportions for the mixture have been recommended by KRAUSE 

 (loc. cit. supra), viz. 4 c.c. of the Saurefuchsin 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. mik. Anat., Hi, 1898, p. 820) gives the proportions 

 2:5:8, 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 colour. The great 

 point of difficulty in working with this stain is to prevent 

 the colour of the methyl green from coming out in the 

 alcohol. 



The best results are obtained with sublimate material ; 

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

 stain. Preparations made with the usual mixture, as given 



