The mercury content of 236 species of wild mushrooms was determined by flameless atomic absorption spectroscopy. Of each species several samples--altogether 616--were tested. The mercury content was between 0.04 and 21.60 mg/kg dry weight, equivalent to 0.002 and 3.090 mg/kg fresh weight. The mercury content was clearly species-dependent. Mercury-rich species particularly were found in Tricholomataceae, Agaricaceae and Lycoperdaceae, whereas in Boletaceae, Amanitaceae and Russulaceae mercury-rich species were rather rare. There was a considerable variability within species, too; hence, other factors, yet unknown, must also determine the mercury content. Geographical influences were not demonstrable. All mushrooms grown on wood had a very low mercury content. Storing over several years did not diminish the mercury content of dried mushrooms. The highest mercury content was found in a poisonous mushroom, but on the average, poisonous mushrooms contained less mercury than edible ones.

Phallolysin, a high-molecular weight, thermo- and alcohol-labile toxin with haemolytic activity, was demonstrated in Amanita phalloides. Phallolysin was isolated from cold aqueous toadstool extracts by precipitation with 40% ammonium sulphate, ion-exchange chromatography on DEAE cellulose, gel chromatography on Biogel P-30 and electrofocussing in Ampholine. Electrofocussing in a flat pH gradient resulted in the separation of the gelchromatographically homogeneous phallolysin into phallolysin A (I.P. 8.06) and phallolysin B (I.P. 7.49). Phallolysin A exhibited 70% purity with respect to its behaviour on polyacrylamide gel electrophoresis when stained with Coomassie Brilliant Blue. On the average 0.62 mug, at least 0.20 mug of protein was equivalent to 1 haemolytic unit (HU). The i.p. LD50 for mice was found to be 1060 (930--1210) HU/kg.

The potassium content of 410 species (1075 samples) of wild mushrooms ranged between 1.5 and 117g/kg dry wt. It was dependent on species and genus, and on the average was highest in Coprinaceae and lowest in Polyporaceae. A positive correlation was observed between potassium and water content; consequently, the potassium content of the wet wt. showed less variation: it ranged between 0.6 and 14.6 g/kg. In the solid matter of single fruit-bodies (11 species) potassium was distributed as follows: flesh of the cap greater than stem greater than gills or tubes greater than spores. The flesh of the cap contained maximally 1.8 times the potassium of the gills. But due to a correspondingly higher water content, significant potassium differences between fresh weights of these parts of fruit-bodies were uncommon. Potassium was concentrated 20--40-fold in fruit-bodies as compared with the soil.--According to our results mushrooms rank among the most potassium-rich vegetables, appropriate for consideration in diets in chronic potassium deficiency. On the other hand, toxic effects must be considered, especially in cases of renal insufficiency.

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