SPECIFIC METHODS. 49 



The pieces embedded in Celloidin are taken .from the spirit 

 and placed for 1 or 2 days in a Saturated Aqueous Solution of 

 Acetate of Copper diluted with an equal bulk of water, kept 

 at about 40 C. (104 F.), and then transferred to 80 p.c. 

 Alcohol till required for cutting : or the sections can be cut 

 first, and afterwards immersed in the Copper Solution. 



The sections are well washed in 90 p.c. Alcohol and 

 transferred to Weigert's Hsematoxylin (p. 26) for a few 

 hours to 2 days, according to the differentiation required, they 

 should be opaque, and a deep blue-black ; and then well 

 washed for 2 or 3 days in Distilled Water. 



They are now decolourised for J to 2 hours in the following 

 solution : 



Borax, 2 grms. ; Ferricyanide of Potassium, 2-5 grms. ; 

 Water, 200 cc. 



While in this solution the sections must be carefully 

 watched, and removed as soon as the grey and white sub- 

 stances are sharply defined. 



They are again washed in Water for half an hour, dehy- 

 drated, cleared, and mounted in Balsam. 



The white substance of Schwann is coloured a purple 

 black, the connective tissue, axis cylinders, ganglion cells, 

 and degenerated tracts in cases of sclerosis, an orange brown. 



PAL'S METHOD. 



A modification of Weigert's. Takes less time, and admits 

 of counter-staining. 



The sections after being cut are placed in the following 

 solution : 



Haematoxylin, 0-75 grms. ; Distilled Water, 90 cc. ; Abso- 

 lute Alcohol, 10 cc. to which is added, just before use, a 

 saturated solution of Lithium Carbonate in the proportion of 



E 



