Xanthene Dyes 191 



certification basis, and can be ordered from any biological supply 

 house. It should be ordered as ethyl eosin rather than alcohol 

 soluble eosin, as the latter name is less definite. 



Ethyl eosin is a valuable counterstain after Delafield's hema- 

 toxylin. Preceding methylene blue, it is employed in demonstrat- 

 ing Negri bodies in the central nervous system of rabid animals. 



For technic of Harris stain for Negri bodies, see Staining Procedures, p. Ill A2-2O. 

 For technic of staining Negri bodies in sections, see Id. p. IIIB3-I2, 13. 



Ri5 EOSIN B (i.e. bluish) c. I. NO. 771 



Synonyms: Eosin BN, BAy BSy BW, or DHV. Saffrosin. Eosin 

 scarlet. Eosin scarlet B. Scarlet J, J J, F. Nopalin G. 



Imperial red. 



This is a dibrom derivative of dinitro fluorescein : 



NaO 



C=^ 



NO. 



I I COONa 

 \/ 



C2oH6N209Br2Na2; Mol. Wt. 624.090 



{An acid dye; absorption maximum 516-519) 



Solubility at 26°C: in water 39.11%; in alcohol 0.75% 



This dye has a distinctly bluer shade than eosin Y; although 

 its absorption maximum is not very different, it has a distinctly 

 different spectral curve, as shown by Fig. 24, p. 188. 



It has occasionally been called for as a counterstain in some 

 histological procedure as, for example, in aqueous solution follow- 

 ing Mayer's hemalum (Kornhauser, 1930), but is not in general 

 very valuable. Lillie (1944c) finds it specially useful, as a neutral 

 stain, for tissues, as an azure A or toluidine blue eosinate. 



Ordinarily, if a shade deeper than eosin Y is desired, better 

 results can be obtained with erythrosin, phloxine or rose bengal 

 than with eosin B. Coleman and Bell, in fact, has put on the 

 market a product labelled * 'eosin, bluish blend," which is a mixture 

 of eosin Y with some one of the dyes just named; it is very satis- 

 factory for certain staining procedures, but must not be confused 

 with true eosin B. 



For technic of Mayer's hemalum with eosin B, see Staining Procedures, 

 p. IA4-I2. 



For technic of buffered azure eosinate method, see Staining Procedures, 

 p. IA4-I2. 



