86 CARMINE STAINS. 



penetration, and stains deep-seated layers of tissue just as well 

 as the superficial ones. The colour of the stain is a somewhat 

 inelegant violet, but this can be changed to a warmer tone by 

 treating the objects with dilute HC1, as for borax-carmine 

 objects. 



152. Alum- Carmine and Picric Acid. Alum-carmine objects 

 may be double-stained with picric acid. LEGAL (Morph. 

 Jahrb., viii, p. 353) combines the two stains by mixing 10 vols. 

 of alum-carmine with one of saturated picric acid solution. 



153. Lithium-Carmine (ORTH, Berlin. Min. Wochenschr., 28, 

 1883, p. 421). Two parts and a half of carmine are dissolved 

 in ninety^seven parts and a half of saturated solution of car- 

 bonate of lithium. 



The solution stains with equal readiness alcohol objects and 

 chromic objects. The stain is diffuse, but becomes restricted 

 to nuclei on treatment with hydrochloric acid (1 per cent, in 

 70 per cent, alcohol) . The stain is permanent both in balsam 

 and glycerin. The great quality of this stain is the readiness 

 with which it stains tissues that refuse to stain in any other 

 medium. It is an excellent reagent, that seems not to be suffi- 

 ciently known. 



154. Aceto-Carmine (Acetic Acid Carmine) (SCHNEIDER'S for- 

 mula, Zool. Anzeig.,No. 56, 1880, p. 254). To boiling acetic 

 acid of 45 per cent, strength add carmine until no more will dis- 

 solve, and filter. (Forty -five per cent, acetic acid is the strength 

 that dissolves the largest proportion of carmine.) 



To use the solution you may either dilute it to 1 per cent, 

 strength, and use the dilute solution for slow staining, which 

 is the method to be preferred for making glycerin prepara- 

 tions ; or a drop of the concentrated solution may be added to 

 a fresh preparation under the cover-glass. 



This is a very important reagent, which in certain cases 

 renders services that no other reagent can render. If you use 

 the concentrated solution, it fixes and stains at the same time, 

 and hence is most valuable for the study of fresh objects. It 

 is very penetrating, a quality that enables it to be used where 

 ordinary reagents would totally fail. The stain is a pure 

 nuclear one. Unfortunately, the preparations cannot be pre- 

 served. 



