Melzer's Reagent

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Melzer's Reagent (also known as Melzer's solution) is a chemical reagent used by mycologists to assist with identifying fungus specimens.

It consists of a combination of iodine with chloral hydrate, potassium iodide, and water. One formulation calls for 100 g chloral hydrate; 10 mL distilled water, 1.5 g iodine, and 5 g potassium iodide.

Three reactions to Melzer's reagent are possible:

• tissues turn blue. This is called an amyloid reaction.
• tissues turn reddish-brown, a dextrinoid reaction.
• tissues do not change color, or become faintly yellow-brown, a negative reaction.

The substance is toxic to humans.

[edit] References

• Baral, H.O. ?. Lugol's solution/IKI versus Melzer's reagent: Hemiamyloidity, a universal feature of the ascus wall. Mycotaxon 29:99-450.
• Blackwell, M., C. David, and S. A. Barker. 2001. The presence of glycine betaine and the dextinoid reaction in basidiomata. Harvard Papers in Botany 6:35-41.
• Blackwell, M., A.J. Kinney, P.T. Radford, C.M. Dugas, & R.L. Gilbertson. 1985. The chemical basis of Melzer's reaction. MSA, Gainesville, Florida, August 1985 (Abstract)
• Kohn, L. M., and R. P. Korf. 1975. Variation in ascomycete iodine reactions: KOH pretreatment explored. Mycotaxon 3:165-172.
• Rossman, A. Y. 1980. The iodine reaction: Melzer's vs. IKI. MSA newsletter 31:22.