430 



E. V. COWDRY 



2. Janus green G(Farbwerke Hoechst Co.) dimethylsafraninazodimethyl- 

 anilin chloride 



N 



(CH3)2N 



N = N 



N(CH3)2 



\/ 



3. Janus green B(Farbwerke Hoechst Co.) diethylsafraninazodimethylanilin 

 chloride 



N 



(C2H8)2N 



N = N r > N (CHs)! 



N. 



^Cl 



Only the latter, janus green B, will stain mitochondria, though 

 the others differ only in the substitution of an H2 or (CH3)2 in the 

 place of the (C2H5)2 group. The poor results obtained with 

 some samples of janus green are probably due to admixtures 

 of the first and second varieties. The azodimethylanilin has 

 but little to do with the specificity of the reaction because it 

 is well known (Shipley '15, p. 86 and Cowdry '14, p. 269) that 

 the diethylsafranin alone will stain the mitochondria more or 

 less specifically. Moreover, I have prepared the safranin from 

 the janus green of Griibler, the dimethylsafranin, from the janus 

 green G of Hoechst, and the diethylsafranin, from the janus 

 green B of the same firm, and I find that the diethylsafranin, 

 alone, will stain the mitochondria. 



There is, in addition to these janus greens, a large series of 

 other janus dyes, manufactured by the Farbewerke Hoechst 

 Company, which thus far have escaped the attention of his- 



