LIGHT GREEN SF, YELLOWISH C. I. NO. 670 



Synonyms: Light green 2G, 3G, 40, or 2GN. Acid green (with 

 various shade designations). Fast acid green N. 



This is a derivative of brilUant green, which is sulfonated and is 

 therefore an acid dye. 



0x12 'CH^ 



/ 

 CH3CH2 /^\^N 



N_/~\_C I CH2_/^\_S03-Na 



/ \_/ l/~\_S03 \_/ 



NaS03_/'~\_CH, \_/ 



\_/ 



(Absorption maximum: 633.5.) 



Light green is a valuable plasma stain often used for staining 

 tissues in contrast to iron haematoxylin, altho it fades badly if 

 exposed to bright light. It is used by Benda in contrast to safranin 

 as a cytoplasm stain for spermatozoa. In plant histology it is a 

 useful cytoplasm and cellulose stain. 



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



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

 term seems to be somewhat loosely used to apply to two or three 

 different dyes and 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 in- 

 troduced 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 groups present. There are four primary 

 compounds theoretically possible, namely with no methyl group, 

 and with one, two, and three substituent methyl groups respective- 

 ly. The types commonly encountered are listed below. 



Basic fuchsin is a very valuable stain, and is one of the most 

 powerful nuclear dyes. It is also a stain for mucin, for elastic 

 tissue, and for bringing out the so-called fuchsinophile granules. It 

 is often used for staining the nuclear elements of the central ner- 

 vous tissue. It is one of the most useful bacterial stains, particularly 

 in the Ziehl-Neelson method for differentiating the tubercle organ- 

 ism and thus diagnosing tuberculosis. As an indicator it is used to 

 distinguish the typhoid organism from other closely related forms 

 by means of the Endo medium, in which it is reduced to the color- 

 less leuco-fuchsin by the use of sodium sulfite. This medium 

 (which contains lactose) remains colorless in the presence of the 

 typhoid organism, which does not attack lactose; but becomes 

 colored in the presence of organisms like Bacterium coli which fer- 



62 



