112 I. WAHL 



nated readily when pieces of barley tissue or sucrose were added. 



In the case of Phycomyces blakesleeanus, Robbins et al.'^^ 

 contend that certain Z factors are essential for spore germina- 

 tion: one of these factors has been identified as hypoxanthine. 



Fries29. 3o obtained spectacular spore germination of some 

 species of Boletus and other Hymenomycetes by sowing the 

 spores on malt agar with cultures of Torulopsis sanguinea. None 

 of the seven species of Boletus investigated germinated on malt 

 agar in the absence of the yeast organism. Fries also found 

 evidence that extracts of Boletus hastened spore germination of 

 the same species. 



Great difficulties have been encountered in germination of 

 basidiospores of the common mushroom Psalliota bispora. 

 Many attempts to induce germination in order to improve 

 commercial strains by selection of monospore cultures resulted 

 in failure until Ferguson^i succeeded in obtaining a high rate of 

 germination by placing spores in the proximity of the growing 

 mycelium. De Zeeuw^^ demonstrated later that a similar stimu- 

 latory effect can be achieved if spores are transferred to agar 

 media on which mycelium of the common mushroom fungus 

 has been cultivated. 



To sum up the discussion on the role of germination activa- 

 tors, R. Brown's^^ opinions may be of special interest. He 

 advances the hypothesis that dilTerent activators operate in the 

 stimulation of various dormant tissues, and that each activator 

 may originate from a large number of species. At least in some 

 cases the activators play an important part in the metabolism 

 of the stimulated and stimulating tissue. 



Attention has been called to differences between dormancy and 

 maturation-^. Stakman and Harrar^ refer to the latter phenome- 

 non as apparent dormancy as contrasted with real dormancy. 

 They emphasize that spores may not be ripe until they are 

 liberated naturally. This was demonstrated with the basidio- 

 spores o^ Pleurotus corticatus in which only naturally discharged 

 spores germinated readily^. Similar observations have been 

 reported with spores of Pseiidopeziza trifolii and P. medicagnis^^. 



