CHAPTER XXXV. 487 



Neuroglia fibres, cytoplasm of neuroglia cells, and glia granules 

 stained in various shades of blue and greyish-blue ; all other 

 elements yellowish-grey or yellowish-brown. 



RANKE (ZtscJir. ges. Neural, u. Psych., vii, 1911, p. 355) uses for 

 similar purposes either celloidin sections of foetal tissues fixed in 

 picric acid-alcohol or sections made by freezing from formalin 

 (pathological) material. In the first case the sections are stuck to 

 slides by pressing with filter paper and then pouring on them methyl- 

 alcohol until all celloidin is dissolved. He next stains them for a 

 few minutes with his acid eosin-thionin solution (see further on), 

 washes with water, and re-stains them, with the help of gentle 

 heat, with 5:1000 Giemsa's " Methylenazur I ' ; quick differen- 

 tiation with distilled water ; 96 per cent, alcohol, cajeput oil, xylol, 

 balsam. In the case of pathological material the sections are first 

 treated with 1 per cent, osmic acid in order to stain fatty products 

 of degeneration, etc., then pressed on to slides and stained as above. 

 To prepare the acid eosin-thionin mixture, mix and shake repeatedly 

 1000 c.c. of each 1 : 1000 watery solution of eosin W.G. and 1 : 1000 

 watery solution of thionin. Leave for forty-eight hours, pour 

 out the fluid part, and wash the sediment into a paper filter with 

 distilled water until the wash water is only a little stained. Dry 

 what remains in the filter, and dissolve it in methyl-alcohol in the 

 proportion of -3 to -5 per cent. 



919. RAMON Y OAJAL'S Gold Chloride and Sublimate Method 



(Trab. Lab. Invest. Bid., Madrid, xi, 1913, pp. 219 and 255 ; xiv, 

 1916, p. 155). At first Cajal used to harden pieces of quite fresh 

 tissues in 14 per cent, formalin, but in his successive papers he 

 recommended fixing from two to ten days in- 



Formol ....... 15 c.c. 



Ammonium bromide .... 1 -5 2 grms. 



Distilled water . . . . . .85 c.c. 



Relatively thick sections (20 to 25 pi) are made by the freezing 

 method, and collected in distilled water to which a few drops of 

 formalin have been added. After a quick wash, batches of four to six 

 sections are each transferred into glass dishes of about 6 cms. in 

 diameter, and each containing 15 c.c. of a mixture of- 



Distilled water .... .60 c.c. 



Corrosive sublimate . . . . .0-5 grm. 

 1 per cent, gold chloride (Merk, brown variety) 10 c.c. 



After^about four hours the sections will be found to have become 



