3. The oxyquinone group. 



e.g., alizarin 



4. The quinone-imide group, including 



(a) Indamins 



(b) Thiazins; e.g., ihionin, toluidine blue, methylene blue. 



(c) Oxazins; e.g., brilliant cresyl blue, Xile bine. 



(d) Azins, including 



(i) Amido-azins; e.g., neutral red. 



(ii) Safranins; e.g., safranin 0, inadgala red. 



(iii) Indulins; e.g., nigrosin. 



5. The phenyl-methane dyes, including 



(a) diphenyl-methanes, e.g., auramin. 



(b) Diamino tri-phenyl methanes; e.g., malachite green, 

 brilliant green, light green. 



(c) Triamino tri-phenyl methanes; e.g., basic fuchsin, acid 

 fuchsin, methyl violet, gentian violet, methyl green, anilifi 

 blue. 



(d) Hydroxy tri-phenyl methanes (Rosolic acids); e.g., 

 aiirin, corallin red. 



6. The xanthene dyes, including 



(a) Pyronins; e.g., pyronin G and B. 



(b) Rhodamines; e.g., Rhodamine B. 



(c) Fluorane derivatives; e.g., eosins, erythrosin, rose 

 bengal. 



(d) Phenolphthalein and the sulphonphthaleins. 



DYE NOMEXCLATURE 



Very little system has been used in naming dyes, and as a result 

 their nomenclature is extremely confused. Generally the manu- 

 facturer of a dye which he thinks is new or which he wishes the 

 public to consider a new dye sells it under a new name which is not 

 intended to give any clue as to the nature of the dye. If the 

 manufacturer knows that the name is a mere synonym of one al- 

 ready in use he does not say so, for he wishes to encourage the sale 

 of his own product rather than that of some other dye maker. 

 Accordingly it has been left for others, who are not financially 

 interested, to work out the synonymy of the dyes; and the list of 

 names that are found to apply to a single dye is sometimes amaz- 



With the dyes in general so unsystematically named, it is natural 

 that the same confusion should reign in the nomenclature of bi- 

 ological stains. This confusion is very unfortunate, for it often 

 misleads the biologist as to just what he is doing. For example, 

 some histologist may have on hand a bottle of stain labeled dahlia 

 and he may find it useful for some new technic, which he publishes; 

 while another may propose for an entirely different technic the 

 stain Hoffman violet. Then a third laboratory worker may read 

 both articles and wish to try both methods; so he accordingly 



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