240 J. W. GROVES ON SECTIONS OF ANIMAL TISSUES. 



better, but has a tendency to produce shrinking in some structures. 

 The indigo carmine solution, introduced by Tiersch, is a good and 

 useful blue stain, especially for sections of brain and spinal cord 

 which have been hardened in chromic acid, and it possesses one very 

 convenient quality — viz., that if the sections are too deeply stained, 

 the excess of colour may be removed by the action of a saturated 

 solution of oxalic acid in alcohol. This reducing process, however, 

 should not be relied on more than is absolutely necessary. It is 

 prepared thus : — 



Oxalic Acid, 1 part. 



Distilled Water, 22 to 30. 



Indigo Carmine, as much as the solution will take up. 



Sections should be immersed in this, diluted with alcohol, from 

 12 to 48 hours, to produce a good colour. 



Carmine, first used by Gerlach, is a most useful tinging agent, and 

 if preparations are not coloured too deeply, it is not disagreeable to 

 the eye. 



Beale's ammoniacal solution is very good, and so is Golding 

 Bird's borax carmine solution, which possesses considerable powers 

 of penetration, so that small masses (about the size of a pea) may 

 be coloured with it before being sectioned ; and if it is diluted with 

 six times its bulk of alcohol, they may be hardened at the same 

 time, and will be ready for cutting in about 10 days. 



Sections stained with the ammoniacal carmine should be washed, 

 and then put into water slightly acidulated with glacial acetic acid 

 (rrtij. — 5i. )> so as to fix the carmine. 



Beale's fluid is thus jjrepared : — 



Carmine, grs. 10. 

 Liq. Amm. Fort, trx. 30. 

 Glycerine, J 2. 

 Distilled Water, | 2. 

 Sp. Vini Rect., 3 ^. 



Dissolve the carmine in ammonia, boil for a few seconds, add the 

 water, filter ; finally add the glycerine and spirit, and keep in a 

 stoppered bottle. Beale says, " Let the excess of ammonia pass off ; " 

 but this is unnecessary, as the excess is very slight. 



Beale's stain reduced with eleven times its bulk of water produces 

 good results in from 12 to 48 hours. 



