Phenyl Methane Dyes 165 



CI CH3 



CH3 CI 



\l 



N=/~'\=C 



/ \^/ 

 CH3 



C27H35N3CI2; Mol. Wt. 472.488 

 {A basic dye) 



Iodine green is a nuclear or chromatin stain which has selective 

 properties that make it of value in certain special procedures. It 

 was used by Ciaccio (1906) for staining nervous tissue, in combina- 

 tion with acid fuchsin and picric acid; by Lefas (see Krause, 1926- 

 7, p. 1122) as a blood stain in combination with acid fuchsin; and 

 by others as a stain for mucin and amyloid which it colors red 

 instead of green. It was employed by Zimmermann (1893) with 

 basic fuchsin for staining chromatin in plant tissue; while together 

 with acid fuchsin it has been proposed by other botanists for stain- 

 ing lignified xylem. Torrey and Buckell (1922) have recom- 

 mended a differential medium for the isolation of the gonococcus 

 which includes this dye. 



ACID VIOLET 



There are various dyes on the market known as acid violet 

 with some shade designation. These dyes vary extremely in 

 composition and they are listed under various Colour Index 

 numbers. They are in general sulfonated violet dyes of the rosan- 

 ilin group, some of them simple methylated pararosanilins, others 

 benzylated compounds. 



Some acid violet — its exact identity uncertain — has been em- 

 ployed by Bailey (1921) in cytological studies on the human 

 pituitary gland; also by Maurer and Lewis (1922) for staining simi- 

 lar tissue from the pig; by Ono (1934) for staining spirochaetes in 

 blood, and by Weiss for staining both spirochaetes (1929) and 

 bacterial flagella (1928). It is very unfortunate that any biologist 

 should have been furnished a stain labeled merely acid violet; the 

 term is too indefinite for identification. 



BENZYL VIOLET 



There is a group of dyes known as benzyl violets, which are 

 pararosanilins with benzyl substitution in one or more of the 



