IODIDE OP PALLADIUM METHOD. 381 



from them, dehydrated and mounted. Axis-cylinders, cells, and processes, 

 grey-black. The sections may be after-stained for a few minutes with O'l 

 per cent, aqueous solution of Bismarck brown. 



726. The method of WOLTEES for axis- cylinder and cell 

 staining (his myelin stains have been given above as modifi- 

 cations of Weigert's) is as follows (Zeit. /. wiss. Mik., vii, 4, 

 1891, p. 471): 



The material (either central or peripheral nervous tissue) is 

 "hardened in liquid of KULTSCHITZKY, 43, followed by alcohol, 

 as there described. It is imbedded either in celloidin or 

 paraffin, and cut. The sections are mordanted for twenty- 

 four hours in the chloride of vanadium and acetate of alu- 

 minium mixture used for Wolters 7 myelin stain, ante, 700, 

 washed for ten minutes in water, and stained for twenty-four 

 hours in the haematoxylin mixture, 699. They are washed 

 out until they are of a light blue-red colour (it is not possible 

 to specify exactly the time required) in 80 per cent, alcohol 

 acidulated with 0*5 per cent, of hydrochloric acid. Eemove 

 the acid thoroughly by washing with pure alcohol, dehydrate, 

 clear with origanum oil, and mount. 



A sharp axis-cylinder stain, myelin being coloured only if 

 the differentiation in the acid alcohol is insufficient. It is 

 applicable to peripheral nerves, and also to the central 

 nervous system. In this, besides axis-cylinders, nerve-cells 

 and their processes are stained; pyramid cells, Purkinje's 

 cells and their processes, and glia cells are sharply brought 

 out. Fine images of epithelium-cells are also obtained ; in a 

 word, besides axis-cylinders, every species of cells present in 

 the preparations are stained. This, and a superior certainty, 

 are the advantages which Wolters claims for his method over 

 that of GOLGI, to which it is in other respects comparable. 



727. PALADINO'S Iodide of Palladium Method (Rendic. R. 

 Accad. Scienze Fis. e Mat., Napoli, iv, 1890, p. 14, and 1891 

 (1892), p. 227; Zeit.f. wiss. Mik., vii, 2, 1890, p. 237, and ix, 

 2, 1892, p. 238; Journ. Roy. Mic. Soc., 1890, p. 817, and 1892, 

 p. 439). Pieces of material hardened in bichromate, chromic 

 acid, or corrosive sublimate, and not more than 5 to 8 mm. in 

 thickness, are put for two days into a large quantity (at least 

 150 to 200 c.c. for each piece) of O'l per cent, solution of 



