NEISSER Solution II (crystal violet) is an aqueous-alcoholic solution of the dye crystal violet and is used in microbiology and bacteriology. The special suitability of this solution lies in its application as a contrast agent in Neisser staining, which is used in particular for the identification of Gram-negative diplococci such as Neisseria gonorrhoeae and Neisseria meningitidis. The solution is used to darken the background of the slides to ensure better visibility of bacterial cells.

Chemically, the operation of the solution is based on the staining of the slide background by crystal violet, a basic dye that binds to acidic components. Denatured ethanol acts as a solvent and improves the solubility of crystal violet in water.

Advantages of NEISSER solution II (crystal violet) lie in its specific use as a contrast agent in Neisser staining. The solution enables effective discrimination of Gram-negative diplococci in microscopic examinations, which can be critical for rapid and accurate diagnosis of infectious diseases caused by Neisseria species.