STAIN TECHNIQUE 57 



cent ammonium alum. Invertebrates are orange-red after 15 min- 

 utes at 50° C. if ferric alum or copper acetate is used as the mor- 

 dant. On most paraffin sections the color is too light. For a gen- 

 eral stain of this color try Direct Fast Scarlet 4BS, C. I. No. 327. 



841. Safranine A, G, O, Y 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 

 J ml. of acetic acid. The letters Y (yellow) and G (gelb) refer to 

 the bright scarlet shade ; A and O indicate a product of the highest 

 purity or of a greater dye content. Safranine is soluble in either 

 water or alcohol. 



Safranine, without the addition of an acid, stains slowly; the 

 color washes out during dehydration. The presence of ammonium 

 alum intensifies the color and reduces the time required for stain- 

 ing. Safranine and alum Haematoxylin is one of the favorite com- 

 binations for leaf, stem, and root sections ; here the lack of contrast 

 between red and purple gives blue or green dyes a preference to 

 Haematoxylin. The material is stained in Safranine long enough 

 to obtain an intense red, one to ten hours, and then, without destag- 

 ing, the contrast color is added. The best counterstains for Safra- 

 nine are : ( 1 ) Aniline Blue, C. I. No. 707, five minutes, (2) Niagara 

 Sky Blue, C. I. No. 520, five to ten minutes, (3) Fast Green FCF, 

 C. I. No. 670, ten to 15 minutes, or (4) alum Haematoxylin. After 

 the material is stained in alum Haematoxylin a rinse in 0.01 per cent 

 ammonium hydroxide will darken the purple pigment. A discus- 

 sion of Flemming's triple stain, Safranine, Orange G, and Gentian 

 Violet is given under Orange G, C. I. No. 27. 



842. Fuchsia, Methylene Violet is a basic dye, light 3. Fuchsia 

 has properties similar to Safranine; the color of stained tissues is 

 more bluish and varies from fuchsia to reddish violet. 



846. Mauveine is a basic dye, light 3. Mauveine, the first dye 

 made from aniline, was discovered in 1856. Paraffin sections of 

 plant tissues are stained blue-violet similar to the color obtained 

 with Methyl Violet. » 



856. Naphthyl Red is a basic dye, light 5. Only the nuclei of 

 mature plant cells are stained a fugitive red. 



857. Magdala Red is a basic dye, light 3 ; 1/10 gram in 100 ml. 



