[Investigations on the stimulation of fruit body formation in aPleurotis from Florida]

Extracts from fruit bodies ofPleurolus orAgaricus promoted fructification ofPleurotus mycelium. This was visible in regular primordia formation 7-10 days after application of extract to the mycelium and in higher sporophore weights.After fractionating the extracts by ultra- and gel-filtration a marked stimulation of sporophore weights was detectable only in fractions of lower molecular weight. The number of primordia, however, was also increased by compounds of high molecular weight, but not by protein alone.With increasing dilution of the extracts the weight of fruit bodies decreased more rapidly than the number of primordia.40 mg of L-asparagine or equimolar amounts of urea showed an effect similar to that of the extract from 1 g fruit body. Suggars gave no reaction.Sporophore initiation and fruit body growth are supposed to be two different processes inPleurotus as well as inAgaricus bisporus.Methods for detecting a hypothetical sporophore inducer and an inhibitor are discussed.