FUNCTIONAL SIGNIFICANCE MITOCHONDRIA 



429 



Chemically, then, we may for the present regard mitochondria 

 as being a combination, in varying amounts, of phospholipins 

 and protein. The phospholipins probably differ in quality 

 as weil as in quantity and this is in all likelihood the case with 

 the protein also. It is probably the chemical basis of the per- 

 plexing differences in solubility and staining reaction, and to 

 a lesser extent, of the differences in form, which mitochondria 

 exhibit in different cells. 



THE JANUS GREEN REACTION 



That mitochondria in living cells stain specifically with janus 

 green was originally discovered by Michaelis ('99, p. 565). 

 Furthermore, when the janus green is reduced by the tissue, 

 a red diethylsafranin is formed which also colors the mitochondria 

 specifically. The delicacy of the reaction is shown by the dilu- 

 tion of the stain which will give it. I have found that mito- 

 chondria will stain in human lymphocytes in a dilution of janus 

 green in physiological saline of 1 : 500,000. This is very remark- 

 able when one reflects that the mitochondria are only about 0.2ju 

 in thickness. But the most significant fact is that the reaction 

 depends upon the presence of two ethyl groups in the safranin 

 portion of the janus green molecule. There are three janus 

 greens of the following formulae:^ 



1. Janus green (Grlibler) safraninazodimethylanilin chloride 



N 



HjN 



N = N 



N> 



^Cl 



N (CHs), 



'' Diazingriin S(K) and Halbwollgrlin B(M) are also janus greens but it is 

 not clear which of the following formulae they possess. 



