PICRO-CARMINE STAINING. 263 



changes of water, and finally transfer them to the green 

 stain, for which take 



Aniline green 5 grains. 



Absolute alcohol I oz. 



Dissolve in a test tube, using a slight heat only, to avoid 

 any unpleasant mishap, and filter before using. After a 

 three hours' soaking in the above, the staining will be com- 

 pleted, and the sections should be mounted without delay, 

 after having washed the superfluous colour away with 

 methylated spirit. The method of mounting these will be 

 given later on. 



Staining in Picro-carmine* Picro-carmine is the most 

 truly selective of any double stain yet employed. A 

 special modification of it is required for wood sections as 

 follows : 



PICRO-CARMINE SOLUTION. 



Carmine (finest) 2 grains. 



Liquid ammonia (sp. gr. '960) .. .. \ drachm. 

 Distilled water I oz. 



Put the carmine in a 2-ounce stoppered bottle, pour in the 

 liquid ammonia, and shake occasionally until dissolved, 

 then add the water. 



Picric acid 8 grains. 



Alcohol .. .. I oz. 



Dissolve in a test-tube with a gentle heat, then mix with 

 the solution of carmine. 



STAINING PROCESS. Place the sections in 50 per cent, 

 alcohol for one hour, then treat with the recently filtered 

 staining solution until the desired effect is produced (usually 

 from half to two or three hours), remove the dye, wash 

 quickly three or four times with alcohol 50 per cent., then 

 soak in an alcoholic solution of picrate of ammonia, 



* Mr. M. H. Stiles in 'The Northern Microscopist,' July 1881. 



