108 

 .6- 



Biological Stains 







0.4 



L.I i I I I I I I I I I I I I I t I I 

 500 540 580 620 660 



Fig. 12. Spectral curves of four thiazin dyes: 



700 



1. Toluidine blue. 



2. Azure A. 



3. Azure B. 



4. Azure C. 



Azure C is recommended by French (1926b) with orange II and 

 eosin as a tissue stain. Haynes (1926a) finds it possible to obtain 

 equally good results, however, with azure I (probably azure A) if 

 the technic is slightly modified. Later (1927) she reports excellent 

 staining with azure C; but it is still uncertain whether it gives re- 

 sults suflSciently different from thionin on the one hand and azure 

 A on the other to be of decided histological value. 



