122 Biological Stains 



k35 CRESYL violet 



CRESYLECHT VIOLET (i.e. CRESYL FAST VIOLET) 



The exact chemical nature of imported cresyl violet is not yet 

 known. Some samples appear to be mixtures of two dyes or 

 possibly two different forms of the same dye. Samples from 

 different sources frequently differ from one another but they are 

 all closely related dyes. Spectral curves of two foreign samples 

 are given in Fig. 14, graphs 2 & 3. They probably represent the 

 type of dye with which biologists were familiar in the days before 

 the world wars. Possibly, to distinguish them from the following, 

 the name "cresyl fast violet" should be retained for this foreign 

 product. It is not at present available. 



At the present time a product of this name put on the market 

 by the National Aniline and Chemical Co. seems to be 

 different from any of the imported samples which have been exam- 

 ined. This National Aniline cresyl violet is better known chemi- 

 cally than the imported product and is considered to have the 

 formula: 



CH3 



\ 



N 



/ \/\_0_/\_NH2 

 CH3 11 I I \ 



/\/-N=\/\ CI 

 CH3 I I 



C19H18N3OCI; Mol. Wt. 339.815 



{A basic dye; absorption maximum 62Jt.-630) 



Solubility at 26°C: in water 0.38%; in alcohol 0.25% 



A spectral curve of this dye is also included in Fig. 14 (graph 1) ; 

 a glance is sufficient to show how different it is from the foreign 

 product. 



Like brilliant cresyl blue, this dye is not employed on a com- 

 mercial scale. Its chief value in histology is on account of its 

 metachromatic properties. It has been employed in making 

 permanent preparations of nervous tissue, and is excellent for 

 staining fresh areolar connective tissue, as it brings out various 

 histological elements. According to Ehrlich (1910, II, p. 78) it 

 stains nuclei violet, plasma blue, amyloid, mucin and mast cell 

 granules red. Spiridonovitch (1924) employs it in the vital stain- 

 ing of white blood cells. Williams (1923) uses it for staining sec- 

 tions of fresh tumor tissue in biopsy work. It is also employed 

 for making permanent preparations of fixed tumor tissue. Landau 

 (1934) proposes it for bulk staining of nervous tissue. 



