STAIN TECHNIQUE 59 



cytoplasm blue-violet. With the addition of ammonium alum to the 

 stain the color on plant tissues is more intense but it is still too fugi- 

 tive to be of much value in histology. 



913. Nile Blue Sulfate is a basic dye, light 2. The dye is 

 slightly soluble in warm water but readily soluble in 50 per cent 

 alcohol. It is unsuited for paraffin sections. Green algae which 

 are usually overstained in basic dyes are colored a clear bright blue. 

 The dye may be used as a vital stain. 



917. Alizarine Green G is an acid mordant dye, light 1 ; 1/10 

 gram in 100 ml. of 1 per cent ammonium acetate. With 1 per cent 

 ferric alum as a mordant followed by the stain for 30 minutes at 

 50° C. the resultant green is the clearest obtained with a mordant 

 dye. Paraffin sections of animal tissues are stained green slightly 

 tinted blue. Various plant tissues appear dull green with the am- 

 monium acetate solution or blue in the stain containing sulfuric acid. 

 Alizarin Green G may be used as a vital or as a fat stain. 



Class XX. Thiamine Colouring Matters 



920. Thionine is a basic dye, light 3; 1/10 gram in 95 ml. of 

 distilled water, 5 ml. of 5 per cent ammonium alum, and J ml. of 

 acetic acid. Plant tissues are stained dark blue to violet. In those 

 examples of contrast staining where Methyl Violet does not differ- 

 entiate well, Thionine may give the desired results. Blue-green 

 algae are stained purple in alkaline solutions of the dye but this color 

 is not fast in glycerin. As a counterstain, Thionine may be used 

 after Acid Fuchsine, C. I. No. 692, Biebrich Scarlet, C. I. No. 280, 

 or Orange II, C. I. No. 151. 



922. Methylene Blue is a basic dye, light 2 to 3 ; J gram in 95 

 ml. of distilled water, 5 ml. of 5 per cent ammonium alum, and h ml. 

 of acetic acid. Unna's polychrome Methylene Blue is Methylene 

 Blue ripened in a solution containing potassium carbonate. The 

 color of the dye is fugitive unless an acid and ammonium alum are 

 added to the dye solution. This dye has been used more than any 

 other basic blue dye for staining bacteria, blood, and animal tissues. 

 Because blood stains provide only temporary mounts, the technique 

 has been omitted. New Methylene Blue is more soluble ; for plant 

 tissues it is a better stain than Methylene Blue. 



