135 



after the reduction of the silver has taken place, be 

 dehydrated in absolute alcohol, cleared in oil of bergamot, 

 and mounted in balsam. 



SILVER NITRATE AND BICHROMATE OF POTASH 

 METHOD (Golgi, Ramon y Cajal, andLenhossek). 



This is a method used for staining nerve cells and their 

 processes both in the central and peripheral nervous system. 

 The formulae here given are taken from Lenhossek's Referat 

 in Fortschritte der Medicin, August and September, 1892. 



Golgi's Slow Method. 



Small pieces of brain or spinal cord are hardened in a 

 2% solution of bichromate of potassium from 20 to 30 

 days; are then, without washing, transferred to a -J-% solu- 

 tion of silver nitrate, in which they remain from 24 to 48 

 hours; or in place of the silver, a 5% solution of bichloride 

 of mercury may be used ; in this they remain from 2 to 4 

 weeks. 



The Mixed Golgi Method. 



The tissues to be hardened and stained are placed in a 

 large quantity (20 to 30 times the bulk of the tissues used) 

 of the following solution : 



Bichromate of potassium . (1% aqueous sol.) 8 parts. 

 Osmic acid . .. . (1% aqueous sol.) 1 part. 



In this they remain four or five days ; are then trans- 

 ferred to 0.75% solution of silver nitrate for 24 to 30 hours. 



Rapid Method (Ramon y Cajal). 



The following solution is now largely used : 



Bichromate of potassium (3 to 5% sol.) 4 parts. 

 Osmic acid . . (1% aqueous sol.) 1 part. 



If it is desired to stain neuroglia cells, allow the tis- 

 sues to remain in the. solution 2 or 3 days ; if nerve cells, 

 3 to 5 days ; if nerve fibres and collateral branches, 5 to 7 

 days. They are then transferred to a 1% aqueous solution 

 of silver nitrate, in which they remain from 24 to 36 hours. 

 Lenhossek adds one drop of formic acid to 200 c. c. of the 

 silver solution. 



