146 Biological Stains 



PROCEDURES RECOMMENDED BY THE COMMISSION IN WHICH THIS STAIN IS USED 



Spectrophotometric curves of typical samples of light green 

 and fast green are given in Fig. 19. It will be seen that they are 

 both very much like the curve for brilliant green, although slightly 

 different from malachite green in the location of the primary 

 absorption maximum. 



Another dye of this group which has been mentioned in biolog- 

 ical literature is: 

 Acid green L Extra; C. I. No. 666. Syn. : Acid green G, B extra, 



GV. Pontacyl green B. 



b. Tri-amino Tri-phenyl Methanes (Rosanilins) 



The simplest rosanilins are the dyes sold as basic fuchsin. This 

 term is somewhat loosely used to apply to two or three different 

 dyes or to various mixtures of them. The dyes known as fuchsin 

 differ from the methyl violets and other rosanilins in that the 

 amino groups are not methylated or substituted in any other way. 

 The fuchsins may, however, have methyl groups introduced 

 directly onto the benzene rings instead of into the amino groups ; and 

 the different fuchsins vary from one another in the number of 

 such methyl groi^jps present. There are four primary compounds 

 theoretically possible, namely with no methyl group, and with 

 one, two, and three substituent methyl groups respectively. 



BASIC FUCHSIN 



Synonyms: Fuchsin RFN. Magenta. Basic ruhin. Anilin red* 



The dyes ordinarily known to commerce as basic fuchsin are 

 represented by C. I. No. 677, which is a mixture of pararosanilin, 

 rosanilin and magenta II. Pararosanilin is obtainable in fairly 

 pure form, as is also the compound with three substituent methyl 

 groups, namely new fuchsin. The formulae of these compounds 

 follow : 



*An impure basic fuchsin known as cerise has been mentioned in the biological 

 literature. 



