DISSOCIATION METHODS. 339 



"Ban. d. nervosen Centralorgane," 1882) is as follows : Tissue 

 hardened in Miiller's solution, washed out, and dehydrated, 

 is put for several weeks into pyroligneous acid. The best 

 acid for this purpose is an " artificial pyroligneous acid," 

 composed of 



Glacial acetic acid . .100 grammes. 



Water ... . 800 



Kreasote . . . xxx drops. 



CARRIERE (Arch. f. mik. Anat., 1877, p. 126) hardens spinal 

 cord for ten days in bichromate of potash or chromate of 

 ammonia of 1 to 600, and macerates for from three to five 

 days in strong solution of ammonia-carmine. 



SCHIEFFERDECKER (Ibid., 1878, p. 38) gives the following 

 method : Pieces of spinal cord about half a centimetre thick 

 are macerated in a small quantity (just enough to cover 

 them) of Kanvier's alcohol (one-third alcohol) for several 

 days. Small fragments of the grey matter are then taken 

 and well shaken in a test-tube with a small quantity of water. 

 There is then added a little glycerin and a few drops of con- 

 centrated solution of picro-carminate of soda, and the whole 

 is set aside for one or two days. Decant, and to the red 

 deposit, which now consists chiefly of stained ganglion-cells, 

 add one or two drops of glycerin, and place the whole for 

 two days in a dessicator with sulphuric acid. (This part of 

 the operation is best performed in a watchglass, or, better, 

 flat-bottomed cell.) The cells are best got on to a slide by 

 pouring a drop of the dehydrated glycerin on to it. 



FREEBORN (Amer. Mon. Mic. Journ., 1888, p. 231 ; Journ. 

 Roy. Mic. Soc., 1889, p. 298) gives the following: Thin slices 

 of spinal cord or cerebellum not over one sixteenth of an inch 

 thick are placed in fifty times their volume of 5 per cent, 

 aqueous solution of potasssium chromate for twenty-four 

 hours. At the end of this time the grey matter has become 

 jelly-like and transparent, and then, having been cut away 

 from the white, is placed in a long narrow tube. Mohr's 

 burette with the lower end plugged with a cork answers the 

 purpose perfectly. The burette is then filled up to within an 

 inch of the top with fresh macerating fluid, and a cork forced 

 in until it comes within half an inch of the surface of the 

 fluid. The burette is then inverted, and this manipulation is 

 repeated at intervals of half an hour until the bits of tissue 



