that hemiamyloid material reacts differently when exposed to Melzer's than it does when exposed to other IKI solutions such as Lugol's, and that in some cases an amyloid reaction is shown in material that had prior exposure to KOH, but an inamyloid reaction without such pretreatment. An experiment in which spores from 35 species of basidiomycetes were tested for reactions to both Melzer's and Lugol's showed that spores in a large percentage of the species tested display very different reactions between the two reagents. These varied from being weakly or non-reactive in Lugols, to giving iodine-positive reactions in Lugol's but not in Melzer's, to even giving dextrinoid reactions in Lugol's while giving amyloid reactions in Melzer's. Melzer's degrades into a cloudy precipitate when combined with alkaline solutions, hence it cannot be used in combination or in direct series with such common mycological reagents such as potassium hydroxide or ammonium hydroxide solutions. When potassium hydroxide is used as a pretreatment, the alkalinity must be first neutralized before adding Melzer's. History The use of iodine-containing solutions as an aid to describing and identifying fungi dates back to the mid-19th century. Melzer's reagent was first described in 1924 and takes its name from its inventor, the mycologist Václav Melzer, who modified an older chloral hydrate-containing IKI solution developed by botanist Arthur Meyer. Melzer was a specialist in Russula, a genus in which the amyloidy on the spore ornamentation or entire spore is of great taxonomic significance. References Further reading Blackwell M, et al. 2001. The presence of glycine betaine and the dextinoid reaction in basidiomata. Harvard Papers in Botany 6:35–41. Rossman AY. 1980. The iodine reaction: Melzer's vs. IKI. MSA newsletter 31:22. Mycology Chemical tests Analytical reagents