62 MICRO-CHEMICAL REAGENTS. 



nuclei and callous-plates remain colored. The 

 latter are very evident, because of their considera- 

 ble refractive power. Such preparations remain 

 unchanged for several months. 



I can recommend this blue for giving a very 

 intense color to bacteria. It is used precisely 

 like methyl violet. The preparations should be 

 mounted in pure Canada balsam, as the chloroform 

 solution removes the coloring matter. 



[More recently methyl blue has been used for 

 detecting the Bacillus of consumption. The tu- 

 berculous matter is dried in a thin film on a cover- 

 glass in the usual way, and then floated for twenty- 

 four hours on a fluid composed of I part saturated 

 methylene blue in alcohol, 2 parts 10 per cent, 

 potash, 200 parts distilled water. After rinsing 

 it is submitted to the short action of a few drops 

 of vesuvin. Only the bacteria retain the blue 

 color. W. T.] 



ANILINE BROWN 



Is used in the same way as methyl violet. 1 It is 

 better than the latter for specimens which are to 

 be photographed ; but the preparations must be 

 mounted in glycerine, since the color is removed 

 by potassic acetate. A concentrated solution in 

 equal parts of glycerine and distilled water is rec- 

 ommended as a staining fluid, the superfluous 

 color being washed away with glycerine. 



1 Koch : Cohn's Beitr., II., p. 406. 



