NUCLEAR STAINS. 33 



and heat gently ; then add 100 cc. of 70 p. c. Alcohol. Filter 

 the solution (if necessary) before use. This is the best solu- 

 lution for staining in bulk. The pieces of tissue should be 

 placed in the solution for 1 to 3 days, and then transferred to 

 Acidulated Alcohol (p. 28). 



Both of the above Borax Carmines are used for staining in 

 bulk, but the Alcoholic solution is better adapted for the 

 purpose, and keeps better than the aqueous which is apt to 

 gelatinize after a time. It also makes a good stain for 

 sections. 



Although Acetic Acid is added to the Aqueous Solution, it does not 

 remain uncombined, so that the staining has still to be supplemented by 

 the usual Acid treatment. 



(viii.) OBTH'S LITHIUM CARMINE. 



Carmine, 2-5 grms. ; Saturated Watery solution of Car- 

 bonate of Lithium, 100 cc. Digest the Carmine in the Lithium 

 solution and filter. 



Saturated Solution of Lithium Carbonate contains 1 grin. Carbonate 

 of Lithium in 70 cc. of Distilled Water. 



A very useful stain. Like other alkaline Carmine solu- 

 tions, it stains both nuclei and ground substance, but is 

 restricted to the nuclei by treating the sections for a short 

 time with Acidulated Alcohol p. 28). 



Lithium Carmine stains alcohol-hardened spinal cord very 

 nicely and quickly. When the staining is deep, extraction 

 with Acidulated 70 p. c. Alcohol gives a sharper definition 

 than Acidulated 90 p. c. Alcohol. 



PICRQ CARMINES. 



Combinations of Carmine with Picric Acid have largely 

 been used as effective double-stains. Various formulae for 

 these solutions exist, in which the Carmine is held in solution 



D 



