440 NERVOUS SYSTEM SPECIAL METHODS. 



For peripheral nerve fibres, GOLGI (Op. Omnia I, p. 162) has 

 proposed two methods. Of these the first is a modification of his 

 rapid process (see 882), and should be carried out as follows :- 

 Tracts of peripheral nerves are cut with care not to stretch them, 

 and put in a mixture of 10 parts of 2 per cent, potassium bichromate 

 and 2 of 1 per cent, osmic acid. After about one hour the tract or 

 tracts of nerves are sufficiently hardened to be further recut in 

 pieces of about | cm. in length, which are put back in the same 

 mixture. After another three hours, and successively at intervals 

 of three hours during twenty-four hours, pieces are transferred into 

 5 per cent, silver nitrate where they may remain for any time, but 

 no less than eight hours. Preparations are made and mounted as 

 above. 



The other method is a modification of that used for central nerve 

 fibres, the only difference consisting in keeping the pieces in the 

 bichromate for a much shorter period, i.e., for from four hours to 

 at most two days, and in transferring specimens into the silver bath 

 at intervals of about three hours. After twelve to twenty-four 

 hours preparations can be made as described above. 



The preparations made by the first method show the spiral 

 filaments very clearly, but do not keep well. The preparations 

 made by the second method do not show the spiral filaments so 

 completely, but are more useful for the demonstration of the funnels 

 and last longer. 



CATTANI (Arch. Ital. Biol., vii, 1886, p. 345) either fixes in Flem- 

 ming's fluid and teases and mounts in glycerine, or puts pieces into 

 Golgi's bichromate and osmic acid mixture, dehydrates and passes 

 into oil of turpentine to be changed until it remains colourless. The 

 turpentine dissolves the myelin and leaves funnels and spiral fila- 

 ments visible. Cattani also has a modified Golgi method, now 

 superseded. 



SALA (Verh. Anat. Ges. Anat. Anz., 1900, p. 176) employs the 

 Golgi- Veratti method for the intracellular network (see 845). 



See also concerning these methods, MONDINO, Arch. p. I. Sc. Med., 

 viii, p. 45. 



GALLI (Ztschr. wiss. Mikr., iii, 1886, p. 467) hardens peripheral 

 nerves for eighteen to twenty days into Miiller's fluid, cuts out 

 pieces 5 to 6 mm. long, and keeps these in Miiller's fluid diluted with 

 2 parts of water for another two days. He then stains for fifteen to 

 twenty minutes in aqueous solution of China blue, washes out in 

 alcohol, clears in essence of turpentine, and mounts in damar. 



RAMON Y CAJAL has successfully employed some modifications of 





