Autogamy stain

Recipe

Reagent	Quantity (for 18 mL)
Acetic acid (45%)	4.5 mL
Acetocarmine	10.5 mL
Fast Green (1% [w/v], prepared in 100% ethanol)	1 mL
HCl (1 N)	2 mL

These proportions are recommended, but if one of the stains is too concentrated (the macronucleus should be reddish and the cytoplasm green when observed under a light microscope), add the other one and check again. Repeat until the desired result is obtained.
This stain (Dippell RV. 1955. A temporary stain for Paramecium and other ciliate protozoa. Stain Technol 30: 69-71) can be kept at room temperature for years.