METHOD XI. 



THE WEIGERT METHOD (PAL'S MODIFICATION). 



A special method for the medullated nerve-tracts of the 

 central nervous system. Applicable for determining both the 

 development and extent of medullation as well as for tracing 

 medullated nerve pathways, and hence is also adapted for the 

 study of the course of degenerated pathways in the central sys- 

 tem. Can be used for determining the number of medullated 

 fibers in a pathway or nerve. 



The method may be applied to material preserved in for- 

 malin. 



SPECIAL REAGENTS REQUIRED. 



A. Fixing agent (Miiller's fluid). — 



Potassium bichromate, 2.5 g. 

 Sodium sulphate, i g. 

 Distilled water, 100 cc. 

 Decide upon the amount needed before making up the fluid. It keeps 

 well. 



B. Stain, Weigert's haematoxylin. — 



Dissolve hsematoxylin crystg-ls, i g. 

 in absolute alcohol, 10 cc, 

 and add distilled water, go cc, -^ 



and cold saturated aqueous solution 

 of lithium carbonate, i cc. 

 Lithium carbonate goes into solution i g. in 80 cc. of cold water. Use 

 distilled water and make up about 100 cc, since it may be needed further in 

 the method. 



C. Differentiating fluids. — 



1. Potassium permanganate, 0.25 g. 

 Distilled water, 100 cc. 



2. Equal parts of a i per cent, aqueous solution of 



oxalic acid and a i per cent, aqueous solution of 

 acid potassium sulphite. 

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