378 



MARGARET R. LEWIS AND WARREN H. LEWIS 



We found that not only do nile blue (A concentrated and B 

 extra) and brilliant cresyl blue (2 b) show the above changes 

 of color found by Smith ('08) with fats but also that each dye 

 changes from blue to pink in the presence of certain other sub- 

 stances as shown in table 1. 



Both brilliant cresyl blue 2 b and nile blue B extra are toxic 

 to the cell, and a preparation never lived more than an hour 

 after even the weakest (1-200,000) solution of the nile blue B 

 extra. Brilliant cresyl blue 2 b is less toxic than nile blue and 

 each of these stains is in a way antiseptic, for no infection took 

 place after the stain was used although the dye was not steri- 

 lized. The color reactions with these stains on the living and on 

 the dead cells are shown in table 2. 



TABLE 1 



NILE BLUE 

 B EXTRA 



Sodium carbonate (in solution) 



Sodium carbonate (dry) 



Lithium carbonate (in solution) 



Potassium hydroxide 



Sodium hydroxide 



Ammonia water 1 



blue 



red 

 pink 

 pink 

 pink 



BRILLIANT CRESYL 

 BLUE 2b 



blue 



bluish violet 

 violet 

 pink 

 pink 



precipitate red dirty brown 



1 solution 



TABLE 2 



CYTOPLASM 



NUCLEOLUS 



FAT 

 DROPLETS 



vacuoles 

 Cfig. 22) 



OTHER MITOCHON- 

 GRANULBS DRIA 



Living cell 



Nile blue 



B extra 

 Brilliant 



cresyl blue 



2b 



clear 



clear 



Dead or fixed cell 



