16 5 



Sections are then washed in absolute alcohol for 30 

 seconds, and in a \% alcohol solution of lichtgriin for 15 

 to 45 seconds, again washed in absolute alcohol, cleared in 

 oil of bergamot, passed through xylol, and mounted in 

 balsam. 



When the stain is properly managed, the chromatic 

 network of the nucleus and the chromosoma of dividing 

 cells are stained red, the protoplasm green. 



Nigrosin and Eosin. 



This method is useful for staining sections of the cen- 

 tral nervous system. Sections are stained for one hour in 

 a \% solution of nigrosin, are then, washed in distilled 

 water for several minutes; they are then placed in a 1% 

 solution of eosin in which they remain from 3 to 5 minutes. 



Wash first in 70% alcohol, then in 95X until no stain 

 is given off from the section. Clear in oil of bergamot, and 

 mount in balsam. 



Aniline Blue and Safranin (Stroebe). 



This method is especially to be recommended for stain- 

 ing peripheral nerves. The method as here outlined is 

 slightly modified from that given by Stroebe. 



The peripheral nerves are hardened in Miiller's fluid, 

 embedded in paraffin, and cut longitudinally or trans- 

 versely. Sections are fixed to cover glas es, the paraffin 

 removed, and carried through alcohol into distilled water. 



1. Sections are then stained for 1 to 5 hours in a satu- 

 rated aqueous solution of aniline blue (Grtibler's wasserlos- 

 liches anilin blau). 



2. They are then rinsed in distilled water. 



3. Decolorize in an alkali alcohol wash, which is pre- 

 pared by dissolving 1 grin, of caustic potash in 100 c. c. of 

 absolute alcohol, and filtering. Just before using, about 

 30 drops of this solution are added to 30 c. c. of absolute 

 alcohol. On placing the sections into the wash, they loose 

 their blue color, and assume a reddish-brown tinge, at the 

 same time reddish-brown waves are given off from the prep- 

 aration. The bleaching is continued until the reddish-brown 

 clouds cease to be given off, usually about 1 to 2 minutes. 



