STAIN TECHNIQUE 51 



In staining mosses, ferns, or seed plants, use a mixture of 

 twenty parts Sun Yellow and one part Acid Fuchsine for 24 hours ; 

 counterstain in New Methylene Blue, C. I. No. 927, five minutes. 

 The basic dye adds a clear outline to the cell walls. Because fun- 

 gous tissues are similar to animal tissues in their reactions to dyes, 

 the combinations given in the previous paragraph should be used. 

 Double stains on vascular plants require Acid Fuchsine for 1 5 min- 

 utes or longer and a counterstain : ( 1 ) Aldehyde Green, C. I. No. 

 676a, 15 minutes, (2) Methyl Violet B, C. I. No. 680, one to three 

 minutes, (3) Methylene Green, C. I. No. 924, 15 minutes, (4) 

 Victoria Blue B, C. I. No. 729, five minutes, (5) Thionine, C. I. 

 No. 920, five minutes, or (6) Opal Blue, C. I. No. 689, one to ten 

 minutes. 



698. Acid Violet is an acid dye, light 4. The dye sold under 

 this name is of variable composition. Because plant tissues are not 

 stained uniformly, a good acid violet may be obtained with Erie 

 Violet BW, C. I. No. 387 ; sometimes Acid Fuchsine, C. I. No. 692, 

 is satisfactory. 



703. Alkali Blue 6B is an acid dye, light 4 to 5. On paren- 

 chyma a fugitive blue to blue-green provides little of value for per- 

 manent slides. In alkaline solutions of the dye, blue-green algae 

 become clear bright blue, but, unfortunately, the color is not fast. 



705, 706, and 707. Aniline Blue water soluble, China Blue, 

 Cotton Blue, Methyl Blue, Soluble Blue, Water Blue are closely 

 related acid dyes, light 3 ; J gram in 95 ml. of distilled water, 5 ml. 

 of 5 per cent ammonium alum, and 1 ml. of 1 per cent sulfuric acid. 



On animal tissues, Aniline Blue and Niagara Sky Blue, C. I. 

 No. 520, comprise an important pair of contrast stains. Should 

 the former of these blue dyes not provide a clear differentiation of 

 tissues, the latter usually supplies the desired quality. In most 

 combinations of stains including Orange G, C. I. No. 27, Orange 

 II, C. I. No. 151, Orange R, C. I. No. 161, Crocein Scarlet MOO, 

 C. I. No. 252, or Sun Yellow, C. I. No. 620, Aniline Blue requires 

 15 seconds to one minute. Aniline Blue is also a constituent in 

 several triple stains which are described under Sun Yellow, Orange 

 II, and Crocein Scarlet MOO. 



