164 



B iolog ica I Stains 



n42 



ETHYL GREEN 



Synonym: Methyl green* 



c. I. NO. 685 



CH, CI 



N_. 



-C 



Br CH.CH, 



1/ 

 _N— CH3 



\ 

 CH, 



CH, 



N 



CH, 



CH, 



C27H35N3CI Br; Mol. Wt. 516.947 

 {A basic dye) 



This dye differs from the preceding only in that it is prepared 

 from crystal violet by the action of an ethyl instead of a methyl 

 halide. It is almost, if not entirely, indistinguishable from C. I. 

 No. 684 by spectrophotometric tests, and apparently acts very 

 similarly for biological purposes. It is entirely possible that it is 

 even better than the other for use in staining; certainly the present 

 methyl greens are more satisfactory than those on the market be- 

 tween 1920 and 1930. 



PROCEDURES RECOMMENDED BY THE COMMISSION IN WHICH EITHER 

 METHYL GREEN OR ETHYL GREEN IS USED 



NAME OF PROCEDURE 



Bismarck brown with methyl green in animal histology 

 Methyl green in glycerin jelly for pollen grains 

 Albert's stain for the diphtheria organism 

 Pappenheim-Saathof stain for gonorrheal pus 

 Saathof stain for bacteria in tissue 



page reference to 

 Staining Procedures 



IA4-5 



nA-13 



IIIA2-II 



IIIA2-I9 



IIIB3-5 



si5 



IODINE GREEN 



C. I. NO. 686 



This dye is closely related to methyl green, the generally accept- 

 ed formula being: 



"This ordinarily occurs in trade as a zinc chloride double salt. 



