METHODS OF STAINING. 369 



3. Transfer to the hematoxylin solution for five to ten minutes. 



4. Wash in tap-water. 



5. Decolorize in the iron solution. 



6. Wash thoroughly in tap- water. 



7. Dehydrate and mount. 



This stain is useful for cytological work, the study of cell division, etc. The 

 preparations are often improved by counterstaining with orange G. 



5. BEALE'S CARMINE. 



Formula : Best carmine, I gm. 



Ammonia, 3 c.c. 



Pure Glycerin, 96 c.c. 



Distilled water, 96 c.c. 



Alcohol, 95 per cent., 24 c.c. 



Dissolve in ammonia plus part of the water, add the rest of the water, and 

 allow the solution to stand in an open dish until the ammonia is nearly all driven 

 off. Then add the alcohol and glycerin. For use dilute with an equal part of 

 glycerin. Stain for twenty-four hours in an open dish, which, together with a 

 second open dish containing acetic acid, is placed under a bell-jar; wash the 

 sections thoroughly in water and then in very weak hydrochloric acid (i c.c. to 

 500 c.c. water), and again in water. 



Beale's carmine is especially valuable for the study of the central nervous 

 system and of the placenta. 



6. WEIGERT'S COPPER HEMATOXYUN. 



formula I : Copper solution : 



Acetate of copper in saturated aqueous solution. 

 II : Hematoxylin solution : 



Hematoxylin crystals, 2 gm. 



95 per cent, alcohol, 20 c.c. 



Distilled water, 80 c.c. 



This stain is indispensable for the study of the nervous system after the 

 medullary sheaths have begun to develop ; the specimens must be preserved in 

 Miiller's fluid. The method is also valuable for the study of the placenta and 

 uterus. 



1 . Place the sections in water. 



2. Place the sections in the copper solution for twenty-four hours. 



3. Wash quickly in water. 



4. Put them in the hematoxylin solution for five to ten minutes. The sec- 

 tions should turn a deep blue-black. 



24 



