Orseillin BB and crystal violet, a differential staining combination for paraffin sections and water mounts of fungi.

A saturated solution of orseillin BB in 3% acetic acid followed by a 1% aqueous solution of crystal violet provides an excellent differential staining for sections of ascomycetous fructifications. The technique stains a wide variety of fungus and host cells, revealing considerable morphological and cytological detail. It is appropriate for microscope slides both of unfixed material mounted in water and of picric acid-fixed paraffin sections.