STAINING 751 



For other more complicated Cajal technics for demonstrating neuro- 

 fibrils, also for the Bielschowsky, Bethe and Apathy methods for the 

 same purpose, reference must be made to the special works on technic. 



Golgi 's Stain for Nerve Cells (cyton, axis cylinder, and dendrons, 

 and neuroglia) : 



I. Mordant : 



' 1 per cent, aqueous solution of osmium tetroxid 10 c.c. 

 3 per cent, aqueous solution' of potassium bi- 

 chromate 40 c.c. 



II. Silver Solution: 



Silver nitrate (crystals) 0.75 grm. 



Distilled water 100 c.c. 



This method is only applicable to fresh tissues, and the best results 

 are obtained when the tissue is taken from a fetus or from an animal 

 not over three days old. Thin slices or small fragments of tissue must 

 be used. 



1. Fix in the mordant for ten days, frequently changing the fluid, 

 which should not become turbid, nor should its odor of osmium tetroxid 

 entirely disappear. 



2. Rinse quickly in water. 



3. Place tissues in the silver solution, diluted with two volumes of 

 distilled water, for fifteen minutes. 



4. Place in the undiluted silver solution twenty-four to forty- 

 ciglit hours. If several pieces of tissue are prepared they should be 

 removed at intervals, as the duration of the impregnation by silver is 

 always an experiment. 



5. Dehydrate in absolute alcohol, one hour. 



6. Transfer to equal parts of absolute alcohol and ether, half an 

 hour. 



7. Thin celloidin (number 1), thirty minutes. 



8. Thick celloidin (number 3), thirty to forty-five minutes. 



9. Transfer to a wooden block and fasten with celloidin. 



10. Harden the celloidin block in chloroform, one-half to one hour. 



11. Cut at once, the sections being 50 p. to 100 /tt thick. While 

 cutting, the knife should be well moistened with bergamot oil, not al- 

 cohol, and the sections, if not mounted at once, may be preserved for 

 a short time in the same oil. Oil of lavender, cajuput, or origanum 

 may be used in a similar manner. 



