STAINING REAGENTS. 65 



filter. Add a drop or two of carbolic acid to preserve it. This 

 gives a diffuse stain, so that the sections have to be treated with 

 acid alcohol (p. 65). 1 

 The original receipt is 



Carmine . . . . .5 to .75 gram. 



Borax . . . . . 2 ,, 



Water ..... 100 cc. 



Alcohol (70 per cent.) . . . 100 ,, 



Borax-carmine is chiefly used for staining tissues "in bulk." 

 Small pieces of tissue, to J-inch cubes or larger, may be left in it 

 for days, and they do not become over-stained. It gives by itself 

 a diffuse stain ; hence to get its effect concentrated upon the nuclei, 

 for which it has a special affinity, the pieces of tissue must be placed 

 for twenty-four hours or thereby in 70 per cent, alcohol containing 

 i per cent, of hydrochloric acid. 



Acid Alcohol. This is called acid alcohol, and is prepared thus 



Hydrochloric acid . . . I cc. 



Alcohol . . . . . . 70 ,, 



Water . . . . . 30 ,, 



When tissues are placed in the acid alcohol, they change in 

 colour to a bright scarlet. A certain amount of the surplus 

 carmine is extracted, but the nuclei become intensely stained. 



This method is particularly valuable for a large number of organs, 

 and especially where nuclear staining is desired. 



7. Alum Carmine. Dissolve 5 grams of potash-alum in 100 cc. 

 water. Add i gram carmine, and boil for a quarter of an hour. 

 Make up the bulk with water and filter. Add a drop of carbolic 

 acid to preserve it, as fungi rapidly form in it. It has the advati 

 tage of not over-staining tissues left in it for a long time. 



8. Lithium Carmine (Orth). 



Carmine . . . . .2.5 grams. 



Saturated solution of lithium carbonate . 100 cc. 



Dissolve the carmine in the cold saturated solution of lithium 

 carbonate ; solution occurs very quickly. It gives a diffuse stain, 

 to nearly all tissues very rapidly, and the sections must, therefore, 

 be transferred, without previous washing in water, to acid alcohol 

 (p. 65). They can then be mounted in glycerine or balsam as 

 desired. The nuclei are stained a brilliant red. It cannot be used 

 for sections fixed on a slide by means of white of egg. 



Application. 



(1.) Stain (2-3 minutes). 



(2.) Washout surplus dye in acid alcohol (\-i minute), i.e., in loo 



cc. of 70 per cent, spirit + I cc. HC1. 

 (3.) Remove all acid by prolonged washing in water. 

 (4.) Alcohol, oil, balsam. 



1 Archivf. Mik. AnaL, vol. xvi. p. 3G3. 



