Staining Method of Dyar
Cetylpyridinium chloride dissociates in water to form positively charged cetylpyridinium and negatively charged chloride ions. As a result of absorption of cetylpyridinium cations on bacterial cell wall, it becomes positively charged and on subsequent treatment with acidic dye like congo red, cell wall is stained, while cytoplasm is stained with basic dye like methylene blue.
The method describe by Dyar (29) is as follows:
