[ 105 ] 



^be flDicroecope anb bow to uae it 



By V. A. Latham, Late Hon. Sec. U.J.F.C, Norwich. 



Part VL — Double Staining (continued). 



Ribesin and Eosin.* — After expressing and throwing away the 

 juice of black currants {Ribes nigrum), boil the skins for some 

 hours in a lo per cent, solution of alum. The resulting deep-violet 

 solution may be conveniently diluted with water, and after a lapse 

 of a day should be filtered, and may be used for staining. The 

 stain resembles Boehmer's Logwood, but is a still more precise 

 nuclear stain. It is a bright, somewhat greenish blue, agreeable, 

 distinct, and permanent. Alcoholic objects stain quicker than 

 chromic acid ones, but the most suitable are bichromate of potash 

 objects. A ribesin stain may be followed by eosin. Brain and 

 spinal cord give good results, especially when hardened in 

 bichromate. 



Carmine Staining with Palladium.— When tissues, and espe- 

 cially nerve tissues, have been over-hardened in chromic acid, 

 carmine may entirely fail to stain them. In such a case, the fol- 

 lowing method (Merkel) is of much service : — Place a large drop 

 of \ per cent, of watery solution of palladium chloride on a slide, 

 and on another slide a large drop of a strong ammoniacal solution 

 of carmine. Allow the section to remain in the palladium for 

 about two minutes. Wash it in water, and place it in the carmine 

 fluid for about three minutes. Then wash again in water. 



To obtain good results with Carmine.— After staining, the 

 superfluous pigment is removed by washing in water acidulated 

 with I per cent, hydrochloric or glacial acetic acid, or in rectified 

 spirit 60 parts, water 39 parts, hydrochloric acid i part (Pritchard). 

 The acid heightens the colour. Tissues stained with carmine may 

 be mounted in Farrant's solution, glycerine, or dammar. 



*See page 41, ante. 



