and tri-phenyl rosanilin: 



CI 



I 



N_ 



T 



H 



_C 



/ 



H 



I 



N 



\_/ 



{Basic dyes; absorption maximum of spirit blue 2R 

 about 581 in alcohol.) 



It is used in contrast to carmin in staining embryonic tissues; it 

 brings out growing nerve fibers well. 



METHYL BLUE C. I. NO. 706 



Synonyms: Cotton blue. Helvetia blue. 



NaSO, 



H 



I 



N 



SO.Na 



{An acid dye; absorption maximum about 607.) 



On account of the sulphonic groups, this dye is strongly acidic 

 and makes a good counter-stain. It is used by Mann with eosin 

 for staining nerve cells; and by Dubreuil, combined w4th picric 

 acid, in contrast to a red nuclear stain such as carmin or safranin. 



ANiLiN BLUE, w. s. (i.e.. Water soluble) c. i. no. 707 



Synonyms: China blue. Soluble blue 3M or 2R. Marine blue. 

 Cotton blue. Water blue. Berlin blue. 



This dye is a mixture of the tri-sulphonates* of tri-phenyl para- 

 rosanilin (C. I. 706) and of di-phenyl rosanilin. The latter is: 



•"The location of the sulphonic groups is uncertain. 



72 



