PERIPHEBAL NERVE-FIBRES 503 



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

 Golgi-Veratti method for the intracellular network (see § 722). 



See also concerning these methods, Moxdino, Arch. p. I. Sc. 

 Med., viii, p. 45. 



Galli {Ztschr. zviss. Mikr., iii, 1886, p. 467) hardens peripheral 

 nerves for eighteen to twenty days in 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 ; then in glycerin acidified 

 W'ith acetic acid (1 drop to 1 c.c.). From this, without washing, 

 the pieces are transferred to a watery solution of China blue, in 

 which they are kept for fifteen to twenty minutes, according to 

 the amount of acetic acid added to the glycerin. They are then 

 brought into alcohol, in which teasing is begun, and then through 

 absolute alcohol into turpentine, in which the teasing is completed. 

 Mount in dammar. 



Ramon y Cajal has successfully employed some modifications 

 of his reduced silver and uranium nitrate methods, for which see 

 Trob. Lob. Invest. Biol., Madrid, x, 1912, p. 221. 



1031. Theory of Impregnation. It was once held that the 

 reaction depends on the formation in the tissues of a precipitate 

 of some salt of silver. And Kallius has put forward the sug- 

 gestion that this precipitate may consist of a protein-silver- 

 chromate combination. But this seems to B. Lee incorrect 

 (see 1913 ed.). In agreement with v. Lenhossek, he finds that 

 the coloration is not due to a visible precipitate, but is a true 

 stain accompanied, particularly in unsuccessful impregnations, 

 by precipitates which not only do not help the stain, but are 

 injurious to it. It has been maintained that the stain is merely 

 superficial, and the method has been called an " incrustation 

 inethod." But it is easy to realise that it generally extends 

 throughout the whole thickness of the impregnated elements, 

 though in special cases or by slight modifications of the original 

 method, the stain may be limited to certain constituents of the 

 nerve-cell body, such as Golgi's pericellular investment ^ and 

 intracellular network. 



The chemical nature of the stain has not as yet been discovered. 



A critical review of the Golgi method by Weigert maybe found in 

 Ergebn. d. Anat., v, 1895, p. 7. See also Hill {Brain, xix, 1896, p. 1), 

 and Kallius {op. cit.). 



MODIFICATIONS OF GOLGI'S BICHROMATE AND SILVER 

 NITRATE METHOD CONCERNING THE IMPREGNATION 

 OF TISSUES. 



1032. Instead of potassium bichromate, ammonium bichromate 

 has been recommended by Golgi and sodium bichromate by 

 Kallius. Both these salts appear to penetrate more quickly 



