MY EL IN STAINS. 415 



STRONG (Journ. Comp. Near., xiii, 1903, p. 291) finds bichromate of 

 copper (of 2 to 3 per cent.) the best mordant ; and that the mordanting 

 is best done before bringing into celloidiii. After staining, he treats 

 for half a minute with osmic acid of P 25 per cent., and differentiates 

 as PAL. 



798. MARCHES Method (for Deganerata Nerves) (Rivista 

 spvrim. di Freniutria, 1887, p. 208 ; Zeit. wiss. Mik., ix, 

 1893, p. 350). --Small pieces of tissue are hardened for a 

 week in solution of Miiller, and then put for a few days 

 into a mixture of 2 parts solution of Miiller and 1 part 1 per 

 cent, osmic acid solution. Sections are cut, best without 

 imbedding, and mounted in balsam. The sheaths in normal 



cv 



nerves then acquire a yellow coloration, those of degenerated 

 tracts a black one. 



This process therefore gives positive images of the 

 degenerated elements, Weigert's process only giving negative 

 ones. 



For a critical review of this method and its modifications 

 see WEIGERT, in Ergebnisse der Anatomie, vii, 1897 (1898), 

 pp. 1 8; MATUSZEWSKF, Arch. path. Anat., 1905, p. 12; DE 

 LANGE, Le Nevraxe, x, 1909, p. 83 ; and LEWY, Fol. Neurobiol., 

 ii, 1909, p. 471 (Zeit. wiss. Mik., xxvi, 1909, p. 290). 



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

 formal ; but this, according to WEIGERT, does not seem recommeiidable. 



FINOTTI (Virchow's Arch., cxliii, 1896, p. 133) 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 (in the dark) 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. For peripheral nerves, myelin (normal), black. 



ORE (Journ. Path, and Bact., vi, 1900, p. 387 ; Jonni. Roy. 

 Mic. Soc., 1900, p. 399) treats with a mixture of 8 c.c. of 

 2 per cent, osmic acid, and 2 c.c. 1 per cent, acetic acid, 

 which increases the penetration. 



VASSALE (Arch. Hal. Biol., 1895, p. 91) takes 75 c.c. of 

 solution of Miiller, 25 c.c. of 1 per cent, osmic acid, and 

 20 drops of nitric <ici<l. 



NISSL (Encijcl. mik. Ttchnik, ii, p. 248), holding that 



