120 METALLIC STAINS. 



218. Cupric Sulphate (see LEBEE, ibid.}. 



219. Lead Chromate (see LEBEE, ibid.). 



220. Sulphides (see LANDOIS, Centralb.f. d. med. Wiss., 1885, No. 55 ; 

 and GIEEKE, in Zeit.f. wiss. Mik., i, 1884, p. 497). 



221. Molybdate of Ammonium (Merkel ; Krause) (see GIEEKE, 

 Zeit.f. wiss. Mile., i, 1884, p. 96). 



222. Osmic Acid. Everybody knows that osmic acid stains tissues. 

 Most people, I should think, would be heartily glad if it did not. Meanwhile, 

 to make the best of this willy-nilly stain, you may sometimes find it useful 

 to treat the tissues with weak pyrogallic acid, which will very quickly turn 

 them of a fine greenish black, sometimes giving useful differentiations. 



Or following BEOSICKE (Centralb.f. d. med. Wiss., 1879, p. 873 ; Zeit.f. 

 wiss. Mik., i, 1884, p. 409) you may treat them for twenty-four hours with 

 a solution of 1 part of oxalic acid in 15 parts of water. This gives a 

 Burgundy-red stain. 



Recommendations of osmium for staining medullated nerve-fibres, as 

 recently advocated by KOLOSSOW (in the place quoted, 28 ; sub finem) 

 appear to me anachronistic. 



223. Impregnation with Fats, Altmann's Method (see post, 530). 



