LIST OF REAGENTS 431 



II. EEAGENTS USED IN STAINING. 



ALUK CASUINE. 



Prepcuration. — Dissolve 200 grms. ammonia alum in water : 

 boil 10 to 20 minutes with excess of carmine : filter : make 

 up to 1 litre with water : add a few drops of oarboUc acid 

 to preserve from mould. 



Use. — Stain for hardened tissues. It may be diluted with 4 

 times its bulk of water or less. 



BOBAX CARMINE (Grenacher's). 



Prepa/ration. — Dissolve 12"5 grms. carmine and 20 grms. borax 

 in 500 e.c. water : add 500 c.c. 70 per cent, alcohol : allow 

 to stand two or three days : filter. 



Use. — Stain for tissues which have been hardened. May be 

 used warm (50° 0.) or cold. The tissues should afterwards 

 be treated with acid alcohol. For staining objects which 

 are to be mounted whole, it should be diluted with several 

 times its bulk of 70 per cent, alcohol, and the treatment 

 with acid alcohol should be prolonged. 



ACID ALCOHOL. 



Prejaa/raUon. — To 100 c.c. of 70 per cent, alcohol add '25 c.c. 



hydrochloric or nitric acid. 

 Use. — For differentiating stained specimens, and for removal 



of surplus stain. 



FICBOCARIUXNE. 



Preparation. — Dissolve 10 grms. carmine in 40 c.c. strong 

 ammonia and 2 Utres water. Add 50 grms. picric acid. 

 Shake well a few minutes : allow to stand : and decant. 

 Allow to stand a few days, stirring occasionally. Evaporate 

 to dryness over a water bath. To every 2 grms. of dry 

 residue add 100 c.c. water. 



Use. — Stain. It may be used with advantage for specimens 

 hardened with osmic acid or otherwise. Subsequent im- 

 mersion for a short time in acid alcohol improves the effect 

 in the case of some tissues. If the object be dehydrated 

 rapidly, or by means of alcohol containing picric acid, a 

 double-stained effect may be obtained, some tissues being 

 stained yellow and others red. 



