PLASMA STAINS WITH GOAL -TAB DYMS. 1 ( -M 



301. Bordeaux R, Thionin, and Methyl Green. (GulBEita, Zeit. 

 wins. Milt., xiii, 4, 13LH>, p. 460). 



335. Congo Rsd (Congoroth) (see GIUESBACH, in Zeit. wisa. 

 Mill., iii, 1866, p. 379). An "acid" colour. Its solution 

 becomes blue in presence of the least trace of free acid 

 (hence Congo is a valuable reagent for demonstrating the 

 presence of free acid in tissues ; see the papers quoted Zoc. 

 cit.). A stain much of the same nature as Saurefuchsin. 

 It is useful for staining some objects during life (see ante, 

 208). CAKNOY (La Cellule, xii, 1897, p. 216) has had very 

 good results with it after haBinatoxylin of DELAFIKLD. He 

 used 0'5 per cent, solution in water. Note that this colour 

 is not to be confounded with other Congos, as Congo yellow, 

 or brilliant Congo. It is one of the azo dyes. 



306. Congo-Corinth. Also an acid dye. HEIDENHAIN (Zeit. wiss. 

 Mik., xx, 1903, p. 179) recommends Congo-Corinth G (or the allied 

 colour Benzopurpurin 6 B) (Elberf elder Farbwerke). Sections must be 

 made alkaline before staining, by treating them with very weak sal 

 ammoniac or caustic soda, in alcohol. After staining, pass through 

 absolute alcohol into xylol. Used after alum hseinotoxylin, the stain of 

 which it does not cause to fade. 



307. Benzopurpurin. According to GRIESBACH (loc. cit., 305), 

 another "acid" colour very similar in its results to Congo red. See 

 also ZSCHOKKE (ibid., v, 1888, p. 466), who recommends Benzopurpurin 

 B, and says that weak aqueous solutions should be used for staining, 

 which is effected in a few minutes, and alcohol for washing out. 

 Deltapurpurin may be used in the same way. 



See last as to the necessity of alkalising the sections, which Heiden- 

 hain states is necessary with all dyes of this group. 



308. Blauschwarz B and Brillantschwarz 3 B (HEIDENHAIN, op. 



cit., 306, p. 183). Acid azo dyes. To be used in 1 per cent, solution 

 with sections of sublimate material, staining for five to ten minutes. 

 Then stain is a basic dye, such as toluidin blue or safranin. 



309. Neutral Red (Neutralroth) (EHELICH, Allg. med. Zeit., 

 1894, pp. 2, 20; Zeit. wins. Mik., xi, 1894, p. 250; GALEOTTF, 

 ibid., p. 193). A u basic " dye. The term " neutral " refers 

 to the hue of its solution. Its neutral red tint is turned 

 bright red by acids, yellow by alkalies. The stain in tissues 

 is in general metachromatic, nuclei being red, cell-bodies 

 yellow (cf. ROSIN, in Deutsche med. Wochensclir . , xxiv, 1898, 

 p. 615; Zeit. wits. Mik., xvi, 2, 1899, p. 238). Up to the 



