METHOD VIII. 



A GOLD CHLORIDE METHOD. 



Applications of gold chloride to either fresh tissue or to tissue 

 which has been preserved in formalin. Especially devised to 

 stain muscle-nerve terminations and peripheral plexuses. 



REAGENTS REQUIRED. 



A. Fixing agent {\o per cent, formalin). — 



Formalin (com. 40 per cent, formaldehyde), 20 cc. 

 Distilled water, 200 cc. 



B. Mordant and fixing agent (10 per cent, formic acid). — 



Formic acid (C. P. cone), 10 cc. 

 Distilled water, go cc. 



C. The stain (i per cent, gold chloride). — 



Gold chloride (aurum chloratum fuscum orflavum), i g. 

 Distilled water, 100 cc. 

 Expose fresh solutions to sunlight one hour before using. 



D. Reducing agent (2 per cent, formic acid). — 



Formic acid (C. P. cone), 2 cc. 

 Distilled water, q8 cc. 



PROCEDURE. 



I. Fix the pieces of tissue containing the regions required in 

 30-40 volumes of 10 per cent, formalin (A) for at least 24 hours. 



The tissue may be preserved in 10 per cent, formalin indefi- 

 nitely and small portions be taken as occasion requires. Good 

 preparations of muscle-nerve terminations have been obtained 

 from material kept in formalin for two years. 



The short muscles, such as the ocular or intercostal muscles, 

 will be found best for motor endings, since the length of the 

 muscle-fiber allows the endings to be found more readily. 



2. Examine the muscle for a branch of the nerve which sup- 

 plies it and clip out small pieces of the muscle (5 mm. long) from 



SI 



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