NEUROGLIA AND SENSE ORGANS 555 



(5) Colour in the following solution, heating to about 50° C. : 

 solution of silver carbonate, 10 c.c. ; pure pyridine, 3 drops ; 

 the sections become a dark sepia colour. (6) Wash in distilled 

 water. (7) Reduce in 10 per cent, formalin. (8) Tone with gold 

 chloride, warming the sections slightly to intensify the colour 

 (9) Fix, wash, dehydrate, clear and mount. 



1098. Oligodendroglia. Robertson {Scot. Med. & Surg. Journ., 

 Jan. 1899, and " Text-book of Pathology in Nervous Diseases," 1900) 

 stained oligodendroglia by placing thin pieces not more than ^V, of an 

 inch in thickness in a mixture of equal parts of | per cent, platinum 

 bichloride (? hydrochloro-platinic acid) and 20 per cent, formalin and 

 leaving them in a dark place for several weeks until they are blackened 

 all over. Thereafter he cut frozen sections and mounted them without 

 further staining. 



Penfield {Brain, xlvii, 1924, p. 430) obtained good staining of 

 oligodendroglia by fixing in ammonium bromide-formalin solution 

 for two to twelve hours only, followed by thirty-six to forty- 

 eight hours in 95 per cent, alcohol, and after a thorough washing 

 of the blocks proceeding as in Hortega's Process III. (§ 1095). 

 He has also {Amer. Journ. Path., vi, 1930, p. 45) stained oligo- 

 dendroglia in material fixed in formalin by placing blocks of 

 tissue in 15 per cent, ammonia for twenty-four hours washing 

 in running water overnight and then transferring them to formalin, 

 20 c.c. ; urea, 4 grm. ; potassium iodide, 6 grm. ; distilled water, 

 80 c.c, for a week, thereafter cutting frozen sections, placing 

 them in 4 per cent, urea overnight and staining in strong, undiluted 

 silver carbonate solution (10 per cent, silver nitrate, 5 c.c. ; 

 sodium carbonate, 20 c.c. ; ammonia to dissolve precipitate), for 

 one minute to one and a half hours. The sections are washed 

 rapidly in 60 per cent, alcohol and reduced in 1 per cent, formalin. 



Cone {Journ. f. Psych, u. Near., xxxiv, 1926, p. 204) stains 

 neuroglia astrocytes and oligodendroglia in tissue fixed in Weigert's 

 " gliabeize " for seven days (with 10 per cent, formalin on first 

 day only), by placing frozen sections, after washing, in 10 per 

 cent, phosj^homolybdic acid for twenty-four hours, thereafter 

 staining in weak silver carbonate (see § 1095) for one to two 

 minutes (for oligodendroglia), or for five to ten minutes (for 

 astrocytes) and transferring directly to 1 per cent, formalin. 



Hortega {Mem. d. I. Real. Soc. Esp. d. Hist. Nat., 1928) fixes 

 pieces of tissue not more than 2 to 3 mm. thick in potassium 

 bichromate, 3 grm. ; chloral hydrate, 2 to 5 grm. ; 10 per cent, 

 formol, 50 c.c, for two to three days. Dial or veronal may be 

 used instead of chloral. After a rapid wash in distilled water the 

 pieces are put into 1-5 per cent, silver nitrate for two to three days 

 in the dark. Frozen sections arc made and as impregnation is 

 never very deep it is advisable to mount the first sections cut. 



Bailey and Bucy {Journ. Path, and Bad., xxxii, 1929, p. 735) 

 stain oligodendroglia by Penfield's method for microglia (§ 1097), 



