406 CHAPTER XXXI. 



with 50 vols. of water. (B) Material that has been in an 

 osmic mixture (liquid of Flemming, of Marchi, or of Grolgi) . 

 Sections as before, then the tannin bath, warming for three: 

 to ten minutes, and the rest as before. 



721. HELLEE and GUMPERTZ (Zeit. f. wiss. Mik., xii, 1896, 

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

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

 The material is hardened in liquid of Miiller. Sections (by 

 the celloidin method if desired) are put into 1 per cent, 

 osmic acid (twenty-four hours at 37 C.) for peripheral 

 nerves, ten minutes (or thirty at the normal temperature) for 

 central. They are treated with pyrogallic acid (a photo- 

 graphic 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; the preparations are then permanent. 

 Mount in glycerin or balsam. 



Similarly KOBEBTSON (Brit. Mcd. Journ., 1897, p. 651; Journ. Roy. 

 Hie. Soc., 1897, p. 175), the material being previously mordanted with 

 Weigert's chrome-alum-copper fluid for neuroglia. 



722. Silver Nitrate. VASTAEINI-CEESI (Att. Accad. Med. Chir. 

 Napoli, 1, 1896) hardens in forraol, cuts 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 per cent, to 70 per cent., then washes 

 thoroughly. 



723. Gold Chloride for Peripheral Nerves (FfiEY, Arch. Anat. 

 Phys., Anat. Abth. Supp., 1897, p. 108. See Grundzilge, LEE & MAYER, 

 p. 421). 



724. Polarisation. Myelin can sometimes be detected by the polari- 

 scope (see AMBRONN & HELD, Ber. Math. Phys. Ges. Wiss. Leipzig, 

 1895, p. 37). They examined teased preparations of peripheral nerves 

 fresh in normal salt solution, or thick sections of nerve centres cut with 

 the freezing microtome. 



See also GAD & HEYMANS, Arch. Anat. Phys., Phys. Abth., 1890, 

 p. 531. 



