376 MAEGARET R. LEWIS AND WARREN H. LEWIS 



VITAL DYES 



Janus green 



Janus green (di-ethyl saffranin azo di-methyl aniline) has been 

 considered a more or less specific stain for mitochondria in the 

 living cell, according to Laguesse ('99), Michaelis ('99), Bensley 

 ('11), Cowdry ('12-' 14). Unfortunately, in our preparations, 

 while the dye stained the mitochondria a brilliant blue-green, 

 it was also toxic to the cells, and even the weakest solution 

 (1-200,000) which definitely stained the mitochondria caused 

 the death of the cells within a few hours. Not only did the 

 dye prevent further growth, but in most instances it also caused 

 various amounts of distortion of the mitochondria. In a few 



Fig. 21 Changes exhibited by 4 different cells after application of Janus green ; 

 in a and b the mitochondria were all long threads before the Janus green was 

 applied and had begun to split up before the drawings could be made. 



cases the mitochondria moved, changed shape and appeared quite 

 normal, although distinctly stained, but usually the mitochon- 

 drial threads or rods separated into granules (fig. 21), shortly 

 after the stain was applied. This is an indication of a slight 

 degree of degeneration on the part of the mitochondria (see 

 experimental work) and possibly the cell is already injured, 

 although not so greatly as to interfere immediately with the 

 activities of the cell, as in many cases the cell continued to 

 move after the stain had been applied and in one observation 

 on a heart muscle cell in which the mitochondria granules were 

 deeply stained with a (1-100,000) Janus green solution the cell 

 continued to beat for one hour and forty minutes. At the end 

 of this time the stain had faded out and the cell ceased to beat. 

 The dye was dissolved in the Locke's solution, which was 

 used for that particular explantation, and after a drop of the 

 solution containing the dye warmed to 39°C. had been dropped 



