92 CYTOLOGICAL TECHNIQUE 



We shall concern ourselves with only live sub-groups of quin- 

 onoid dyes. All the dyes mentioned in this book are listed here 

 for convenient reference, under the names of their groups and 

 sub-groups. 



Dyes are not known by their full chemical names, because 

 these would be inconveniently long. Shorter names are used, 

 many of which are to some extent descriptive. Initial letters, 

 written in capitals, often form part of a name; these serve to 

 distinguish a dye from others that are closely related. Thus SS 

 means spirit-soluble (soluble in ethanol, not in water); G means 

 gelb (yellow). The B of azure B is an arbitrary mark of distinction 

 from two closely related dyes called azures A and C. 



QUINONOID DYES 



Triarylmethane 



Cationic. PararosaniHne, rosaniline, methyl violet, crystal 



violet, aniline blue SS 

 Anionic. Methyl blue 



Haematein 



Anionic. Haematein 



Anthraquinonoid 



Anionic. Alizarine, purpurine, carminic acid 



Xanthene 



Anionic. Eosin 



Thiazine 



Cationic. Thionine, azure B 



AZO DYES 



Mono-azo 



Anionic. Orange G 



QUINONOID DYES 



Triarylmethane dyes. These may be regarded as derived from 

 leuco-pararosaniline, which is a colourless substance, since it 

 possesses no chromophore. Leuco-pararosaniline itself is methane 

 in which three of the four hydrogens have been replaced by aniline. 



