416 CHAPTER, XXXTIT. 



alcohol attacks the myelin, cuts without imbedding, and 

 hurries through alcohol and bergamot oil into balsam. 



RAMON Y CAJAL (Trab. lab. Biol. Madrid, ii, 1903, p. 93) has an 

 inadmissably complicated method of treating Marchi material. 



BUSCH (Neurol. Centralk., xvii, 1898, p. 476 ; Zeit. wiss. 

 Mik., xv, 1899, p. 373) puts/orraoZ material for five to seven 

 days into a solution of 1 part osmic acid, 3 of iodate of 

 sodium, and 300 of water. Same stain as Marches, but 

 more penetrating and sharper. 



See also VENOEROVIC, Anat. Anz., xxxix, 1911, p. 414 

 (cuts slices of the formol material 0'5 cm. thick, and osmicates 

 these, thus getting increased depth of reaction). 



797. Osmic Acid (ExNER, Sitzb. Akad. Wiss. Wien, 1881, Ixxxiii, p. 151 ; 

 BE VAN LEWIS, The Human Brain, p. 105). A portion of brain, not 

 exceeding a cubic centimetre in size, is placed in 1 per cent, osmic acid, 

 and after five to ten days is cut (best without imbedding). The sections 

 are treated by caustic ammonia (20 drops to 50 c.c. of water), which 

 clears up the general mass of the brain substance, leaving the medullated 

 fibres black. The preparations are not permanent. To make them so 

 (RANVIER, Traite, 1 ed., p. 1086) they should be fixed for a quarter of 

 an hour in osmic acid vapour. 



798. AZOULAY'S Osmic Acid Method (Anat. Anz., x, 1894, 

 p. 25). (A) Sections of Miiller material are put for five to 

 fifteen minutes into solution of osmic acid of 1 : 500 or 

 1 : 1000 strength. Rinse 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. If the sections are too thick it will be 

 necessary to differentiate by PAL'S process, or by eau do Javelle 

 diluted with 50 volumes of water. (B) Material that has been 

 in an osmic mixture (liquid of Flemming, of Marchi, or of 

 Golgi). Sections as before, then the tannin bath, warming 

 for three to ten minutes, and the rest as before. 



799. HELLER AND GUMPERTZ (Zeit. wiss. Milt., xii, 1896, 

 p. 385) give for peripheral nerves, and HKLLER (op. cit., xv, 

 1899, p. 495) for central nervous system, the following: 

 Sections of Miiller material are put into 1 per cent, osmic 



