554 NEUROGLIA AND SENSE ORGANS 



rises in ammonium bromide, 15 grm. ; 40 per cent, formaldehyde, 

 100 c.c. ; distilled water, 400 c.c. Without washing, the sections 

 are placed in antiformin, 3 c.c. ; 95 per cent, alcohol, 8 c.c. ; 

 distilled water, 2 c.c. ; for five to eight seconds. After a thorough 

 washing in two changes of distilled water the sections are trans- 

 ferred to an ammoniacal silver solution prepared by mixing 5 c.c, 

 of 10 per cent, silver nitrate with 15 c.c. of 10 per cent, caustic 

 soda and dissolving the precipitate with ammonia. The sections 

 must be kept moving in this solution for eight to ten seconds. 

 They are reduced in 2 per cent, formalin, washed and toned. 



Belezsky {Virchow's Arch. f. Path. Anat., cclxxxii, 1931, 

 p. 214) has stained microglia in celloidin sections. After a pro- 

 longed wash in distilled water the sections are placed for twenty 

 minutes in the following solution : to 5 c.c. of 17 per cent, silver 

 nitrate add 5 drops of 40 per cent, caustic soda. Dissolve the 

 precipitate with 25 per cent, ammonia and dilute about forty 

 times. The sections are reduced in 10 per cent, formalin after a 

 quick wash in distilled water, the reduction being accelerated by 

 heat. 



Stern {Zeitschr. f. d. ges. Neurol, u. Psychiat, cxxxviii, 1932, 

 p. 769) also stains microglia in celloidin sections, which, after 

 prolonged washing in distilled water are placed in the following 

 solution for five to thirty seconds : to 4 c.c. of 10 per cent, silver 

 nitrate add 2 or 3 drops of strong ammonia and then a few more 

 drops to dissolve the precipitate which forms. Dilute with 20 c.c. 

 of distilled water. Transfer sections without washing to 10 to 20 

 per cent, formalin, keeping the sections moving until reduced. 

 If the sections are left longer (thirty to sixty seconds) in the 

 ammoniacal silver or are allowed to sink to the bottom of the 

 reducing dish, oligodendroglia will be stained. 



Weil and Davenport {Arch. Neurol, and Psychiat., xxx, 1933, 

 p. 175) have modified the above method for staining microglia in 

 celloidin sections. They add 10 per cent, silver nitrate drop by 

 drop from a burette to 2 c.c. of concentrated ammonia, shaking 

 the solution to avoid a precipitate. The end point is given by a 

 slight opalescence. Sections are left in this solution for ten to 

 twenty seconds and reduced without washing in a solution of 

 formalin, 1 part ; distilled water, 5 parts ; moving the sections 

 about until they are of a coffee-brown colour. 



Del Rio Hortega's Method for Pineal Parenchyma. (Horrax 

 and Bailey, Arch. Neurol, and Psijchiat., xiii, 1925, p. 423.) 

 (Originally published in Arch, de Neurobiol., iii, 1922, p. 351. 

 (1) Fix in 10 per cent, formalin for at least two days. (2) Cut 

 thin frozen sections. (3) Place for twenty-four hours at room 

 temperature in : 10 per cent, silver nitrate, 10 c.c. ; pure pyridine, 

 3 drops ; the sections become dark yellow. (4) Wash in distilled 

 water to which 2 drops of pure pyridine have been added. 



