556 NEUROGLIA AND SENSE ORGANS 



using 10 per cent, ammonia instead of weak ammonia for the 

 preliminary washing overnight and substituting a saturated 

 solution of lithium carbonate for sodium carbonate in the silver 

 carbonate solution. 



Weil and Davenport {Arch. Neurol, and Psychiat., xxx, 

 1933, p. 175) stain oligodendroglia in celloidin sections by treating 

 the sections with 10 per cent, ammonia water before staining 

 them in a solution prepared as for staining microglia in celloidin 

 sections (see § 1097), but using 15 per cent, silver nitrate. Weaker 

 formalin (10 per cent.) is used for reduction and the sections are 

 allowed to drop to the bottom of the dish until the celloidin is 

 stained brown. They are then moved about until the sections 

 are coffee colour. 



1099. For Mitochondria and Gliosomes, Del Rio Hortega 

 {Bol. de la Soc. Esp. de Hist. Nat., 1925, p. 34) fixes small pieces 

 for two to three days at 25° to 35° C. or for four to eight days at 

 room temperature in a mixture of 10 per cent, formalin to which 

 is added either 6 to 8 per cent, of iron alum or 1 to 2 per cent, 

 uranium nitrate. He uses three modifications in staining these. 

 (a) Frozen sections are made, washed in distilled water and 

 stained in the silver carbonate solution used in Process III, and 

 thence reduced in ^ per cent, formalin, after washing for mito- 

 chondria, but without washing for gliosomes. Tone in gold and 

 fix in hyposulphite, {b) Specially for gliosomes, but revealing 

 also the processes of neuroglia cells. Fixation for two to eight 

 days in iron-alum formalin, or after fixation in formol-bromide 

 place for twenty-four hours in iron-alum solution. Frozen sections 

 are washed first in two or three changes of water containing a 

 few drops of ammonia and then in pure distilled water. Stain in 

 10 c.c. of silver carbonate solution to which is added 3 drops of 

 pyridin, heating to 45° to 50° C. until the sections take a light 

 tobacco colour. Wash one to three minutes in distilled water and 

 reduce in 10 per cent, formalin, (c) Specially for the specific 

 granules of ependymal cells. Fix in iron-alum and formol- 

 bromide solution (10 per cent, formol, 2 per cent, ammonium 

 bromide, 6 to 8 per cent, iron alum) for three to four days. Frozen 

 sections are washed as in (b) and transferred first to 2 per cent, 

 silver nitrate for ten to fifteen minutes, then after a rapid wasn 

 to silver carbonate for one minute. After the most rapid wash 

 possible they are reduced in 1 per cent, formalin. 



Methods (a) and (c) after formol-uranium nitrate fixation are 

 specially suitable for gliosomes and for interfascicular oligo- 

 dendroglia. 



METHODS FOR SENILE PLAQUES 



1100. Marinesco {UEncephale, xxiii, 1928, 697) places pieces 

 of formalin fixed material not more than 8 mm. thick in 96 per 



