counterstain in methylene blue, aqueous solution thirty seconds.
counterstain with Kuehne's carbolic methylene-blue for one or two minutes.
counterstain very lightly with aqueous solution of Neutral Red.
counterstain coun·ter·stain (koun'tər-stān')
A stain of a contrasting color used to color the components in a microscopic specimen that are not made visible by the principal stain.