Appendix B: Some Standard Reagents and Their Uses 185 



fixative. There are various formulae for making the stain. One 

 of the oldest and at the same time one of the best is the formula 

 of Ranvier. 



Ranvier^s formula. A saturated solution of carmine in ammo- 

 nia is added to a saturated aqueous solution of picric acid to the 

 point of saturation (that is, until precipitation begins). The 

 mixture is next evaporated down to one-fifth of its volume and 

 filtered after cooling. The solution is then evaporated until only 

 a powder remains. A 1 per cent, solution of this powder in dis- 

 tilled water is used for staining. It is well to allow the stain to 

 act for from 12 to 24 hours. If the material is to be mounted in 

 glycerin, it should first be treated (by irrigation under the cover- 

 glass) with formic-glycerin (formic acid 1 part, glycerin 100 

 parts) for several days until proper differentiation has taken place. 

 If osmic acid has been used for fixing, nuclei should appear red, 

 muscle tissue straw yellow, elastic fibres canary yellow, connec- 

 tive tissue pink, and keratohyalin red. 



64. Pyrogallol. Tissues which have been fixed in Hermann's 

 or in Flemming's fluid for 24 to 36 hours may be treated (with- 

 out previous washing) with a weak solution of pyrogallol or 

 with crude pyroligneiis acid. Lee (Microtomisf s Vade-Mecum) 

 recommends the pyrogallol as much preferable. Tissues should 

 remain in the fluid from 1 to 24 hours depending upon size. The 

 result is a black stain which colors both nucleus and cytoplasm. 

 If desired, an additional chromatin stain may be employed. 

 Safranin (65) for 24 hours is recommended; decolorize slightly 

 with very dilute acid alcohol. The stain is excellent for cy to- 

 logical work (for "sphere," etc.). 



65. Safranin. Safranin is one of the most important of the 

 basic anilin dyes. Read carefully the remarks on anilin stains 

 under 29. 



Safranin 1 gram 



Anilin water (see 29) 90 c.c. 



Alcohol, 95 per cent 10 c.c. 



Filter before using. Griibler's "Safranin O" is the most reli- 

 able dye. Sections of tissues fixed in Hermann's or Flemming's 



