METHOD IV. 



APATHY'S AFTERGILDING GOLD CHLORIDE METHOD/ 



An application of gold chloride to sections of material pre- 

 viously fixed. A method for the neurofibrillae and also 

 adaptable to the study of nerve terminations and the general 

 internal morpljology of the neurone. 



SPECIAL REAGENTS REQUIRED. 



A. Fixing fluid. — 



Sodium chloride, 0.25 g. 



Distilled water, 50 cc. 



Corrosive sublimate (Hg CI 2), 3 g. 



I per cent, osmic acid, 50 cc. 

 Note. — Mix in the order given. The corrosive sublimate would best be 

 dissolved before the osmic acid is added. The osmic acid solution is 

 generally kept in stock. Osmic acid is sold in sealed glass tubes containing 

 a stated weight of the crystals. Owing to the great readiness with which it 

 becomes reduced in the presence of impurities, great care must be taken in 

 making solutions. Clean the sealed tube thoroughly, finally rinsing in 

 distilled water, place in a clean bottle, add the required amount of distilled 

 water and crush the tube with a clean glass rod. 



B. Washing fluid. — 



Potassium iodide, I g. 

 Distilled water, too cc. 

 Iodine, 0.5 g. 



C. Impregnating fluid {\ per cent, gold chloride). — 



Gold chloride (aurum chloratum fuscum or flavum), I g. 

 Distilled water, 100 cc. 



D. Reducing fluid (i per cent formic acid).— 



Formic acid (pure), 6 cc. 

 Distilled water, 600 cc. 



' Stefan ApAthy, " Das leitende Element des Nervensystems und seine 

 Beziehungen zu den Zelleu,'' Mitth. Zool. Station N'eapel, Bd-.X.!!, 1897. See also 

 ApAthy, Zeitschrift fiir wiss. Mikroskopie, Bd. XV, H. I, 1898.^ 



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