Appendix B: Some Standard Reagents and Their Uses 175 



several days for this to occur. The above mixture constitutes a 

 stock solution which should be diluted with about 50 or 100 times 

 its volume of water before using. According to Lee (Microt- 

 omist's Vade-Mecum), "if a drop be placed on blotting paper it 

 should form a spot bluish green in the center, orange at the 

 periphery. If the orange zone is surrounded by a broader red 

 zone, the mixture contains too much fuchsin." For use with this 

 method, -tissues should be fixed in pure corrosive sublimate solu- 

 tion. Sections should be thin (3 to 5 microns) and must remain 

 in the stain from 18 to 24 hours. They should then be rapidly 

 washed in 95 per cent, alcohol, placed for a short time in absolute 

 alcohol and cleared in xylol. If the sections remain in the alco- 

 hols any considerable length of time, the methyl green will be 

 extracted. The stain is very uncertain in its action but when 

 successfully applied the results are excellent. It is used chiefly 

 in cytological studies, especially in connection with gland cells. 

 Grtibler prepares a dry powder for this three-color mixture, but 

 the results are usually not as satisfactory as when the mixture is 

 properly made fresh. To prepare the stain from the powder, a 

 0.4 per cent, solution of the latter in distilled water is made, 

 and to 100 c.c. of this solution 7 c.c. of a 0.5 per cent, aqueous 

 solution of acid fuchsin are added. 



39. Ehrlich's "Triacid" Mixture. For blood films Ehrlich's so- 

 called triacid mixture is a serviceable stain which is widely used. 



Orange G, saturated aqueous solution . . . 14.0 c.c. 



Acid fuchsin, saturated aqueous solution . 7.0 c.c. 



Distilled water 15.0 c.c. 



Absolute alcohol 25.0 c.c. 



Methyl green, saturated aqueous solution . 12.5 c.c. 



Glycerin 10.0 c.c. 



Each solution must be thoroughly saturated (several days). Add 

 the ingredients in the order named, shaking the mixture well 

 between each addition. It is best for the stain to stand a week 

 or two before it is used. Neutrophil granules stain violet, oxy- 

 phil granules a brownish red. The mixture stains in from 

 5 to 15 minutes. 



40. Eosin. See chap, i, reagent 17. This anilin dye is often 

 used after hematoxylin as a contrast stain. It is specific for cer- 



