Quinone-imine Dyes 123 



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WAVELENGTH m }i 



Fig. 14. Spectral curves of cresyl violet. 



1. National Aniline product. 



2. Kresylecht violet from Bayer; 3. from Grubler. 



There is evidence that a stain satisfactory for one of these two 

 latter purposes may not yield good results with the other. Wil- 

 liams, for example, finds rather better results with the National 

 Aniline product in biopsy work, while from other quarters com- 

 plaints have been received concerning the same batch of this dye 

 when used for making preparations from fixed tumor tissue, for 

 which the imported dye is very satisfactory. 



There have been conflicting reports about the relative merits of 

 domestic and foreign products for neurological work. Quite un- 

 satisfactory results have been reported with the National Aniline 

 product as a stain for Nissl granules; but Banny and Clark (1950) 

 find that a cresyl violet just obtained from Coleman and Bell is 

 satisfactory. Their finding has not been verified by others. Fur- 

 thermore, the latter product is not the same as the foreign samples 

 shown by graphs 2 and 3 in Fig. 14. It is believed to be a diethyl 

 (instead of dimethyl) amino compound. 



It is plain that further work is necessary both on the chemistry 

 of the imported product and on comparative value of the two 

 types in staining. Experimental work on this dye has not pro- 



