MYEFiTN STAINS. 417 



acid (twenty-four hours at 37° 0. for peripheral nerves ; ten 

 minutes, or thirty at the normal temperature, for central). 

 They are treated with pyrogallic acid (a photographic 

 developer will do) till the nerves are black, then with a 

 violet-coloured solution of permanganate of potash till the 

 sections become brown, then with 2 per cent, oxalic acid till 

 they become yellow-green. Wash out well between each 

 operation. 



Similarly, Teljatnik {Neurol. Ceniralb., 1897, p. 521) ; Robbbtson 

 {Brit. Med. Journ., 1897, p. 651 ; Journ. Roy. Mic. Soc, 1897, p. 175), 

 the material being previously mordanted with Weigert's chrome-alum- 

 copper fluid for neuroglia; and Ore, Journ. Path, and Bad., vi, 1900, 

 p. 387. See also Rossolimo & Btjsch, Zeit. wiss. Mik., xiv, 1897, p. 65. 



WiTTMAACK {Arch. Ohrenheilk., Ixi, 1905 ; Encycl. mik. 

 Technik, ii, p. 241) mordants till green (temporal bones) in 

 90 parts of Miiller with 10 of formal and 3 to 5 of acetic 

 acid, decalcifies with nitric acid and formol, treats sections 

 (paraffin or celloidin) for a few minutes with osmic acid of 

 2 per cent., and reduces in pyrogallol of 5 per cent. Shows 

 the least traces of myelin. 



800. Iron. — Allbrhand {Neurol. Centralb., xvi, 1897, p. 727; Encycl. 

 mile. Technilc, p. 944) puts sections of Miiller material for fifteen 

 minutes into warm 60 per cent, solution of Liquor ferri sesquichlorati. 

 then for an hour or two into 20 per cent, tannin solution (old and 

 brown). They are then diiferentiated by the method of Pal, taking, 

 however, the liquids twice as strong. 



An iron-alum process is described by Steong in Journ. comp. Neurol., 

 xiii, 1903, p. 291. 



801. Silver Nitrate. — Vastaeini-Ceesi {Att. Accad. Med.-Chir. 

 Napoli, 1, 1896) hardens in formol, outs thick sections, washes them 

 with 40 per cent, alcohol, puts them in the dark into 1 per cent, solution 

 of nitrate of silver in alcohol of 40 to 70 per cent., then washes thoroughly. 



Similarly, Mosse {Arch. mih. Anat., lix, 1901, p. 401), impregnating 

 bichromio material with 1 per cent, solution of argeniamiii, and reduc- 

 ing in 10 per cent, pyrogallic acid, and differentiating by the method of 

 Pal. (Argentamin is an alkaline solution of equal parts of phosphate 

 of silver and ethylendiamin in 10 parts of water). 



802. Polarisation. — Myelin can sometimes be detected in fresh 

 matericd by the polariscope, see Ambeonn & Held, Ber. Math. Phys. 

 Gen. Wiss. Leipzig., 1896, p. 37, and Gad & Heymans, Arch. Anat. 

 Phys., Phys. Abth., 1890, p. 631. 



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