METALLIC STAINS (IMPREGNATION METHODS). 217 



path. Anat., xix, p. 451). Physiological salt solution (0'75 

 per cent.) is commonly used for these washings. 



MULLKR (Arch. f. path. Anat., xxxi, p. 110), after impreg- 

 nation by immersion for two or three minutes in a 1 per cent, 

 solution of nitrate of silver in the dark, adds to the solution 

 a small quantity of 1 per cent, solution of iodide of silver 

 (dissolved by the aid of a little iodide of potassium). After 

 being agitated in this mixture the preparations are washed 

 with distilled water, and exposed to the light for two days 

 in a 1 per cent, solution of nitrate of silver (see also GIERKE, 

 in Zeit. wiss. Mil'., i, 1884, p. 396). 



ROUGET (Arch, de Physiol., 1873, p. 603) reduces in 

 glycerin; SZUTZ (Zeit. wiss. Mik., xxix, 1912, p. 291) in 

 glycerin with ^ of formol. 



SATTLEU (Arch. Mik. Anat., xxi, p. 672) exposes to the 

 light for a few minutes in water acidulated with acetic or 

 formic acid. THANHOFFER (Das Mikroskop, 1880) employs a 

 2 per cent, solution of acetic acid. 



KRAUSS brings his preparations, after washing, into a light 

 red solution of permanganate of potash. Reduction takes 

 place very quickly, even in the dark. 



OPPITZ puts for two or three minutes into a 0'25 or 0'50 

 per cent, solution of chloride of tin. 



JAKIMOVITCH (Juurn. de VAnat., xxiii, 1888, p. 142) brings 

 nerve preparations, as soon as they have become of a dark 

 brown colour, into a mixture of formic acid 1 part, amyl 

 alcohol 1 part, and water 100 parts, and exposes to the 

 light for five to seven days, the mixture being renewed 

 from time to time. 



DEKHUYSEN (op. cit., last ) reduces in oil of cloves, after 

 dehydration. 



355. Fixation. LEGEOS (Journ. de V Anat., 1868, p. 275) washes his 

 preparations, after reduction, in hyposulphite of soda, to prevent after- 

 blackening. According to DUVAL (Precis, p. 230) they should be washed 

 for a few seconds only in 2 per cent, solution and then in distilled 

 water. 



GEROTA (Arch. Anat. Phys., Phys. Abtli., 1897, p. 428) reduces in a 

 hydroqninone developing solution, followed by fixation in hyposulphite 

 of soda, just as in photography. 



356. Impregnation of Marine Animals.^ On account of the 



