NEUROLOGICAL METHODS. 405 



For a critical review of this method and its modifications 

 see WKIGERT, in Ergebniase der Anatomie, vii, 1897 (1898), 

 pp. 18. 



The method has been applied to tissues that have been hardened in 

 formol ; but this (WEiGEET, loc. cit.) does not seem recommendable. 



VASSALE (Arch. Ital. Biol., xxiv, 1895, p. 89; Zeit. f. wiss. Mik., xiii, 

 4, 1896, p. 495) modifies the fluid by taking 1 per cent, osmic acid one 

 part, and three parts liquid of Miiller, and adding twenty drops of nitric 

 acid to 100 c.c. of the mixture, but only advises the modification for large 

 specimens which have been a long time, four to five months, in the liquid 

 of Miiller. 



FJNOTH (Virchow's Arch., cxliii, 1896, p. 133; Zeit. f. 

 wiss. Nik., xiii, 1896, p. 237) makes sections of material 

 that has been in liquid of Miiller for not more than a few 

 weeks or months, and puts them for four to ten hours into a 

 freshly prepared mixture of one or two parts of 1 per cent, 

 osmic acid and one part of a concentrated solution of picric 

 acid in one third alcohol (the mixture must be protected 

 from light during the reaction). For peripheral nerves, 

 myeliii (normal),, black. 



BUSCH (Neurol. Centralb., xvii, 1898, p. 476 ; Zeit. f. 

 wiss. Mil\, xv, 1899, p. 373) puts formol-hardeiied material 

 for five to seven days into a solution of one part osmic acid, 

 three of iodate of sodium, and 300 of water. Same stain as 

 Marchi's, but more penetrating and sharper. 



TELJATNIK (Neurol. Centralb., 1897, p. 521 ; WEIGEET (op. cit, supra, 

 p. 5) impregnates as Marchi, and afterwards treats with permanganate and 

 oxalic acid as in the method of PAL ( 712). 



See also EOSSOLIMO & BUSCH, Zeit.f. wiss. Mik., xiv, 1897, p. 55. 



720. AZOULAY'S Osmic Acid Method (Anat. An?:., x, 1, 1894, 

 p. 25). (A) Sections of material that has been for several 

 months in liquid of Miiller are put for five to fifteen minutes 

 into solution of osmic acid of 1 : 500 or 1 : 1000 strength. 

 Einse with water and put them for two to five minutes into 

 a 5 or 10 per cent, solution of tannin, warming them therein 

 over a flame till vapours are given off, or in a stove at 50 

 to 55 C. Wash for five minutes in water, double-stain if 

 desired with carmine or eosin, and mount in balsam. Thin 

 sections are necessary to ensure good results. If they 

 should be too thick it will be necessary after staining to 

 differentiate by PAL'S process, or by eau de Javelle diluted 



