550 NEUROGLIA AND SENSE ORGANS 



reduce for half a minute in 20 per cent, formalin, neutralised by shaking 

 with chalk, wash, dehydrate and mount. 



Modification J II. — Particularly good for collagenous fibres, but also 

 for neuroglia fibres. Proceed as in Modification II until the sections 

 are placed in the staining bath ; keep them therein until brown ; reduce 

 and fix as in Modification I. 



Modification IV (op. cit., xvi, 1918, p. 375, note). Suitable for 

 the demonstration of the protoplasmic neuroglia. Frozen sections 

 of formalin material are treated for some minutes at 15° to 50° C. 

 with a mixture of tannin, 3 grm. ; ammonium bromide, 1 grm. ; 

 distilled water, 100 c.c. Wash and stain as in Modification I ; 

 reduce in 20 per cent, formalin neutralised with chalk ; tone with 

 0-2 per cent, gold chloride ; fix, wash, dehydrate and mount as 

 usual. 



Ramon y Cajal {Trab. Lab. Invest. Biol, xviii, 1920, p. 129) 

 stains iienroglia astrocytes by a modified Bielschowsky technique, 

 fixing in formol-bromide solution as above and after making 

 frozen sections refixing them in 6 per cent, ammonium bromide 

 in either water or 12 per cent, neutral formalin for four to six 

 hours in the oven at 37° C. or for eight to twelve hours at room 

 temperature. Wash quickly in two changes of water and place 

 in a silver bath made in the following way. Add 12 drops of 

 40 per cent, sodium hydroxide to 10 c.c. of 10 per cent, silver 

 nitrate, wash precipitate six to seven times with distilled water 

 and dilute with 60 to 70 c.c. of distilled water before dissolving 

 with ammonia. Of this strong solution put 3 to 5 c.c. into each 

 of several dishes and add to each 15 c.c. of distilled water and 

 2 to 4 drops of pure pyridin. Put sections into these dishes and 

 keep them first for five to ten minutes in the cold and thereafter 

 warm till the sections take a tobacco colour. Keeping the 

 sections warm, wash for a few seconds in a large amount of distilled 

 water and place in 20 per cent, neutral formol. Wash rapidly in 

 water and tone in Merck's brown gold chloride for several hours 

 in the cold or for ten to twenty-five minutes at 37° C. Fix, 

 dehydrate, mount. 



He also {Arch. Swisses de Near. & Psych., xiii, 1923, p. 187) 

 recommends his uranium nitrate method, as devised for staining 

 Golgi's internal apparatus (§ 724), for the demonstration of 

 protoplasmic and fibrous neuroglia cells and also for gliosomes and 

 lipoid inclusions. 



1095. Del Rio-Hortega's Carbonate of Silver Method {Trab. 

 Lab. Invest. Biol., Madrid, xv, 1917, p. 367, and xviii, 1920, p. 37 ; 

 Bol. Sac. Esp. Biol., viii, 1918). Pieces of quite fresh nervous 

 tissues are fixed in Cajal's ammonium bromide-formalin mixture, 

 and kept therein for different periods of time, according to the 

 purposes in view. If it is desired to stain the protoplasmic 

 neuroglia, pieces are best fixed for twenty to thirty or forty days ; 



