The vital staining of mitochondria with janus green etc. 271 



These were seen to stain brightly with janus green when it was in- 

 troduced at the side of the cover glass and drawn through by means 

 of filter paper. Blood smears were fixed in Orth's fluid, Altmann's 

 fluid, Bensley's osmic bichromate acetic mixture, osmic acid solution 

 and osmic acid vapor. They were stained by the Altmann procedure 

 and by Bensley's anilin fuchsin methyl green and toluidin blue methods. 

 In these preparations structures were observed in the leucocytes which 

 were indistinguishable on the basis of their relative number, shape 

 and cytoplasmic distribution from the bodies seen in the living, 

 unstained cell, on the one hand, and in cells stained supravitally 

 with janus green, on the other. There can be no doubt therefore 

 of the pre-existence of these bodies in the cells of the circulating 

 blood of the normal, human adult and of the value of these new 

 methods of approach. 



Observations. 



The evidence is strong, to my mind conclusive in favor of the 

 mitochondrial nature of the bodies about to be described. It is based 

 upon the following observations: 



1. Eeaction to vital dyes. 



They stain in a specific fashion with janus green. This has 

 been shown to be a property of mitochondria in all tissues which 

 have been investigated, except in rare instances where the cells are 

 not permeable to the dye. It has been recorded by Michaelis 

 ('99, p. 666) in gland cells; by Laguesse ('11, p. 275) in the pancreas; 

 by Bensley ('11, p. 304) also in the pancreas; by Lewis ('14, p. 331) 

 in tissue cultures and by myself ('12, p. 8; and '14, p. 398) in adult 

 and embryonic nerve cells. Moreover I have found that janus green 

 will stain bodies which are unquestionably mitochondria in other cells, 

 for example endothelial cells, side by side with mitochondria in blood 

 cells, in the same field of the microscope. Both the endothelial cells 

 and the blood cells were human and were taken fresh from the 

 operating room through the courtesy of Dr. Dandy of the Johns 

 Hopkins Hospital. 



