198 Silver Impregnation II (chap. 15) 



procedure: 



1. Transfer to 80% alcohol: 6 hours. 



2. Treat with ammoniacal alcohol: 24-36 hours. 



(a) For cerebrum, cerebellum, spinal cord, or ganglia add 4 drops 

 of ammonia to 50 ml. of 95% alcohol. 



(b) For medulla, add 9 drops of ammonia to 50 ml. of 95% 

 alcohol, 



3. Wash in distilled water, several changes, until pieces sink. 



4. Treat with pyridine: 1-2 days. 



5. Wash in running water: overnight, followed by distilled water, 

 several changes. 



6. Blot on filter paper and place in relatively large volume of 1.5% 

 silver nitrate, aqueous (1.5 gm./lOO ml. water): 5 days in dark, 

 38°C. 



7. Rinse in distilled water and place in following fluid: 24 hours. 

 Ramon y Cajal's reducing fluid: 



pyrogallic acid or hydroqviinone 1.0 gm. 



distilled water 100.0 ml. 



neutral formalin 15.0 ml. 



8. Rinse in distilled water, several changes over a period of at least 

 1 hour. 



9. Dehydrate and embed in paraffin, celloidin, or double embed. 



10. Make sections perpendicular to surface of organ and about 15 or 

 more microns thick. 



11. Affix to slides, dry, remove paraffin with xylene and mount. Lay 

 celloidin sections on slides and mount in resin. 



results: 



neurofibrils — black 

 background — brownish yellow 



Nerve Cells and Fibers 



Golgi's Rapid Method (mallory, 1938) B 

 fixation: fix small pieces in: 



potassium dichromate, 2.5% aqueous 40.0 ml. 



osmic acid, 1% aqueous 10.0 ml. 



Place cotton in bottom of container so fixing fluid has access to all 

 sides: 1-7 days. Renew fixative if it becomes turbid. 



