466 NERVOUS SYSTEM— GENERAL METHODS 



Its special value for the nervous system lies in the fact that 

 it differentiates neuroglia from collagen fibres and so outlines 

 sharply the limits of the blood-vessels and meninges. For the 

 use of this stain on celloidin sections we recommend the following 

 technique : Sections of 8 to 10/u, are transferred from spirit to water 

 and stained for two to five minutes in Weigert's iron haema- 

 toxylin, or in Hansen's iron-alum ha?matoxylin. They are then 

 thoroughly washed in alkaline tap-water and differentiated in 

 acid alcohol if necessary. (Up to this point several sections 

 may be treated at a time but from this stage on they must be 

 treated individually.) Sections are passed into van Gieson's 

 counterstain by means of a fine bent glass -rod, and moved about 

 in the stain for eight to twelve seconds (here careful timing is 

 necessary), then washed quickly in distilled water or in tap- 

 water made acid with acetic acid, washed again quickly in 70 

 per cent, alcohol, and transferred to 95 per cent, alcohol, where 

 they are left for from five to fifteen minutes. This wash in 

 alcohol removes the picric acid from the nuclei, leaving them 

 clear blue. They are then cleared in carbolxylol, washed in 

 xylol and mounted in xylol balsam saturated with salicylic acid 

 crystals (Roussy & Lhermitte). 



It is important that after van Gieson's counterstain the sections 

 should not enter any alkaline solution. If mounted in acid 

 balsam, the red staining of the fuchsin is permanent and the 

 salicylic acid does not appear to cause the haematoxylin to fade. 



Rawitz (Ztschr. iviss. Mikr., xxvi, 1909, p. 341) has some compli- 

 cated methods with Indulin, Indaminblau, and Azosaureblau, which take 

 twenty-eight days ; and {ibid., xxviii, 1911, p. 1) others with fuchsin 

 and azofuchsin which take over thirty-six days. 



Ariens Kappers {ibid., xxviii, 1911, p. 417) describes a staining 

 method with extract of elderberries for material fixed and hardened in 

 Mailer's fluid or similar solutions. It is very simple and particularly 

 recommended for photographic purposes ; it should be carried out as 

 follows : Stain ceUoidin or paraffin sections overnight in neutralised 

 elderberries extract (obtained by fermentation at 20° to 25° C), to which 

 1 per cent, carbolic acid has been added. Wash in water. Differentiate in 

 3 per cent. Liquor ferri sesqiiichlorati P. G., wash, dehydrate, and mount. 



998. Methods for Staining in Bulk. Pick {Centralb.f. GynakoL, 

 xxii, 1898, p. 227) suggested staining and fixing frozen sections 

 at the same time in a mixture of 10 per cent, formalin and alum 

 carmine. 



ScHRiDDE and Fricke {Centralb. f. allg. path. u. path. Anat., 

 xvii, 1906, p. 720) fix small pieces of tissue in 9 parts alum carmine 

 with 1 part formalin for three to four days or longer, wash for 

 twelve to twenty-four hours and differentiate in 200 parts of 

 75 per cent, alcohol with 1 part of 25 per cent, ammonia. 



RoTHiG {Folia NeurobioL, ii, 1909, p. 385) fixes and stains 

 for about four weeks in saturated solution of methylenazur I. 



