172 TEXT-BOOK OF FUNGI 



LUMINOSITY OF FUNGI 



The fact that certain fungi emit a more or less brilliant 

 phosphorescent glow has long been known. The pheno- 

 menon is most frequently connected with Agarics, and 

 more especially species of Pleurotus, and has been recorded 

 from Brazil, Borneo, India, Java, Australia, etc. The olive- 

 tree agaric, Pleurotus olearius, is the most conspicuous 

 example in Europe of a luminous fungus. Cortirium 

 coeruleum, Armillaria mellea, and the ascigerous species, 

 Xylaria hypoxylon, and X. polymorpha, are also said to 

 be luminous. Sterile mycelium in decayed wood, rhizo- 

 morphs, and sclerotia also possess the same property. The 

 following account by Berkeley will give some idea of the 

 phenomenon. A quantity of wood had been purchased 

 in a neighbouring parish, which was dragged up a very 

 steep hill to its destination. Amongst it was a log of 

 larch or spruce, it is not quite certain which, twenty-four 

 feet long and a foot in diameter. Some young friends 

 happened to pass up the hill at night and were surprised 

 to find the road scattered with luminous patches, which, 

 when more closely examined, proved to be portions of 

 bark or little fragments of wood. Following the track, 

 they came to a blaze of white light which was perfectly 

 surprising. On examination, it appeared that the whole 

 of the inside of the bark of the log was covered with a 

 white byssoid mycelium of a peculiarly strong smell, but 

 unfortunately in such a state that the perfect form could 

 not be ascertained. This was luminous, but the light was 

 by no means so bright as in those parts of the wood where' 

 the spawn had penetrated more deeply, and where it was 

 so intense that the roughest treatment scarcely seemed to 



