METALLIC STAINS (IMPREGNATION METHODS). 227 



This method has been attributed to VON MAEHRENTHAL. See also 

 under "Nervous System" modifications of this method by AZOULAY 

 and HELLER and G-UMPERTZ ; also one by KOLOSSOW (Zeit. iviss. Mik., 

 ix, 1892, p. 38, and ix, 1893, p. 316). 



375. Perchloride of Iron. This reagent, introduced by POLAILLON 

 (Jo urn. de VAnat., iii, 1866, p. 43), sometimes gives useful results, 

 especially in the study of peripheral nerve-ganglia, in which it stains 

 the nervous tissue alone, the connective tissue remaining colourless. 



The HOOGANS proceed as follows (J'nurn. Quekett Club, 1876 ; Journ. 

 Roy. Mic. Soc., ii, 1879, p. 358) : The tissue (having been first fixed 

 with silver nitrate, which is somewhat reduced by a short exposure to 

 diffused light) is dehydrated in alcohol, and treated for a few minutes 

 with 2 per cent, solution of perchloride of iron in spirit ; then with a 

 2 per cent, solution of pyrogallic acid in spirit, and in a few minutes 

 more, according to the depth of tint required, may be washed in water 

 and mounted in glycerin. 



FOL fixes in perchloride ( 80) and treats for twenty-four hours with 

 alcohol containing a trace of gallic acid. 



POLAILLON (loc. cit.) reduces in tannic acid. 



The method is not applicable to chromic objects. 



GOLODETZ and UNNA (Monats. prakt. Derm, xlviii, 1909, p. 153) 

 put sections of skin for 5 minutes into fresh mixture of 1 per cent, per- 

 chloride of iron and 1 per cent. sol. of ferricyanide of potassium. 

 See also UNNA and GOLODETZ, ibid., xlix, 1909, p. 97. 



ROOSEVELT (Med. Rec., ii, 1887, p. 84 ; Journ. Roy. Mic. Soc., 1888, 

 p. 157) employs a stain composed of 20 drops of saturated solution of 

 iron sulphate, 30 grins, water, and 15 to 20 drops pyrogallic acid. 



376. Palladium Chloride (see SCHULZE, 77). Prussian Blue (see 

 LEBER, Arch. Oplithalm., xiv, p. 300 ; RANVIER, Traite, p. 108). Cupric 

 Sulphate (see LEBER, ibid.). Lead Chromate (see LEBER, ibid.). 

 Sulphides (see LANDOIS, Centralb. med. Wiss., 1885, No. 55; and 

 GIERKE, in Zeit. wiss. Mik., i, 1884, p. 497). Molybdate of Ammonia 

 (MERKEL ; KRAUSE) (see GIERKE, ibid., i, 1884, p. 96). Oxychloride of 

 Ruthenium (NicOLLE and CANTACUZENE) (see Ann. Inst. Pasteur, vii, 

 1893, p. 331). Ruthenium Red (Ruthenium Sesquichloride) (EiSEN, 

 Zeit. wiss. Mik., xiv, 1897, p. 200; in my hands totally useless). Oxide 

 of Manganese (GOLODETZ and UNNA, Monats. prakt. Derm., xlviii, 

 1909, p. 151). 



