METHOD IX. 



THE GOLGI METHOD. 



A method for the external morphology of the neurone, cen- 

 tral and peripheral ; to demonstrate the shape of the cell-body, 

 the dendrites and their "gemmules," the axone and its branch- 

 ings, collaterals, and terminations. Also for neuroglia and for 

 the non-nervous tissue elements of the organs of special sense. 



1. " The rapid method." 



2. Application to material preserved in lo percent, formalin. 



REAGENTS REQUIRED FOR BOTH APPLICATIONS. 



A. Fixing fluids. — 



1. 3.5 per cent, potassium bichromate (B), 85 cc. 

 I per cent, osmic acid, 15 cc. 



One per cent, osmic acid is made by dissolving one gram of osmic acid 

 (Os O4) crystals in 100 cc. of distilled water. For precautions in making the 

 solution see IV, A, note, p. 31, 



2. 10 per cent, formalin (see VIII, A). 



Prepare a quantity of the fluid which will be 8-10 times the volume of the 

 tissue to be fixed. 



B. Mordant (3.5 per cent, potassium bichromate). — 



Potassium bichromate (crystals pulverized), 7 g. 

 Distilled water, 200 cc. 



C. Impregnating fluid (0.75 per cent, silver nitrate). — 



Silver nitrate (crystals), 1.5 g. 

 Distilled water, 200 cc. 

 Formic acid (cone.) i drop. 

 The formic acid is thought to aid in the reduction of the silver nitrate, 

 but it may be omitted. 



D. Ether-alcohol. — 



Absolute alcohol, 150 cc. 

 Sulphuric ether (pure), I 50 cc. 



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