Organic Substances 97 



the dye caused by solvent evaporation, an occurrence often 

 experienced with alcohoHc solutions. 



Method 



Carry frozen sections in 50 per cent alcohol for a few min- 

 utes. Stain in a saturated and filtered solution of any of the 

 dyes mentioned in 70 per cent alcohol or 60 per cent triethyl- 

 phosphate for 5-20 minutes. Differentiate in 50 per cent al- 

 cohol for about 1 minute. Counterstain as desired. Mount in 

 glycerin-gelatin or some similar medium. 



Pure kerasin stains intensely with Sudan III, while the 

 kerasin-protein complex of Gaucher cells does not. Franco 

 and Wolman-^ find that boiling the sections at pH 4 for 30-60 

 seconds will break the complex and make the cells intensely 

 sudanophilic. 



Nile blue is different from the other dyes in several re- 

 spects. First of all, it is water-soluble; second, it has two com- 

 ponents: a blue oxazin and a red oxazone dye;^^"^^ third, be- 

 sides being an oil dye, it is also a regular basic dye, staining 

 nuclei blue and mucin metachromatically pink.^^ 



The value of Nile blue has been a subject of much debate 

 ever since its introduction into histological technique by 

 Lorrain Smith.^^ It appears, however, that the investigations 

 of Cain-^ have settled the argument once and for all. Tri- 

 glycerids, whether saturated or not, are colored red by the 

 oxazone, provided that the temperature of staining is not be- 

 low their melting points. All acidic lipids, (including fatty 

 acids and phospholipids ) are stained blue because they bind 

 the oxazin base (pink itself) in the form of blue salts. In 

 mixtures, intermediate shades will be obtained. 



22. Franco, S., and Wolman, M.: Schweiz. Ztschr. f. Path. u. Bakt., 10:49, 

 1947. 



23. Smith, J. L.: J. Path. & Bact, 12:1, 1908. 



24. Lison, L.: Bull, d'histol. apphq. a la physiol., 12:279, 1935. 



25. Cain, A. J.: Quart. J. Micr. Sc, 88:383, 1947. 



26. Baker, J. R.: Quart. J. Micr. Sc, 85:1, 1944. 



