FUNCTIONAL SIGNIFICANCE — MITOCHONDRIA 431 



tologists. I have made a special study of them. Janus blue 

 G and R, janus grey B and BB, janus black D, I, II and O and 

 janus yellow G and R are of particular interest because they 

 are safranin derivatives, the others being dyes of the triphenyl- 

 methane and other series. 



Janus blue is diethylsafranin-i3-naplithol and it stains mito- 

 chondria in living lymphocytes in a constant and specific fashion. 

 It is inferior to janus green in that it will only stain mitochondria 

 in these cells in a dilution of 1 : 300,000. As an indicator of 

 processes of reduction it is, however, better than janus green 

 for the contrast between the blue of the dye itself, and its red safra- 

 nin base is more brilliant than in the case of janus green. The 

 marks 'G' and 'R' indicate, according to Schultz ('14, p. 48), 

 that the janus blue is made by two processes, from clematin 

 (mark 'G') and from safranin T (mark 'R'). 



Janus black I also stains mitochondria in living blood cells 

 specifically, but, on analysis, I find that it is not a pure dj^e but 

 a mixture of two substances, diethylsafranin-azodimethylanilin 

 and a brown substance, the natiu'e of which I am unable to 

 determine. Thus, the specificity of janus black I for mito- 

 chondria is undoubtedly due to the fact that it contains janus 

 green as one of its ingredients. 



I have isolated the diethylsafranin from janus blue, janus 

 black and janus grey (I failed with janus yellow) and they 

 all stain mitochondria, which is further evidence that the speci- 

 ficity of janus green depends upon the diethylsafranin group. 

 It may be said that the staining is favored by the addition of 

 azodimethylanilin to it, as in janus green; increased, though not 

 so much by adding /3 naphthol; and altogether prevented by 

 the addition of other groups in janus grey. 



It is exceedingly difficult to determine whether this staining 

 of mitochondria is a chemical or a physical process. Cham- 

 bers ('15) has arrived at the conclusion that it is net due to a 

 chemical combination. 



