metachromasy

from The Century Dictionary.

• noun An anomalous manner of staining, whereby a single stain will color different tissue elements in different tints or in altogether different colors: a term introduced by Ehrlich. Not all dyes have metachromatic properties. The most notable ones are methyl-violet, thionin, methylene-azure, cresyl violet RR, and toluidin blue.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Metachromasia.