English: Amiloid reaction:

Peziza vesiculosa (the bladder cup, blistered cup, common dung cup) is a fungus that, pursuant to the taxonomic classification, belongs to the division Ascomycota, family Pezizaceae. The species forms cup-shaped fruiting bodies attached to the substrate. The hymenium is formed on the inner surface of the cup.

For this experiment, two microscopic slides with different reagents are prepared, one with water and one with Melzer's reagent, in order to perceive the differences in the reaction, the color alteration of the structures. Melzer's reagent is an aqueous solution of chloral hydrate, potassium iodide, and iodine in a certain ratio. Peziza vesiculosa has a positive amyloid reaction, i.e. iodine reacts with polysaccharides, resulting in dark-blue color of the asci, which is particularly intense in the apex of the ascus. The preparation made in water does not produce reaction, and the structures do not alter color.

In this experiment, a dried specimen of Peziza vesiculosa has been rehydrated before the preparation of the microscopic slide, i.e. it has been left to soak in water for some time. A microscopic glass slide is prepared by placing one drop of water on one side and one drop of Melzer's reagent on the other side. Cross sections of the fruit body are made as thin as possible. The pieces of thin sections are set into the reagents, and a cover glass is laid on top. The cover glass is gently pressed with absorbent paper so that the material can adhere to the glass and be placed in one plane. Excess of reagents is also removed. It is evident that the material prepared in water produces no staining at all while the material in Melzer's reagent is dark to light-blue in color. First, the microscopic slide prepared in water is scrutinized, and it is noticeable that asci are transparent as well as spores, and ornamentation of small warts on spores surface is apparent. Later, the preparation in Melzer's reagent is examined, and it is observable that the asci are blue- colored. The asci tips are colored most intensely while spores display no reaction.

Planned and performed by Slavica Tofilovska and Katerina Rusevska, Department of Biology, FNSM, Ss. Cyril and Methodius University, Skopje, Macedonia.