438 



RESEARCHES ON FUNGI 



demonstrate the phenomenon of biohiminescence to students and 

 friends.^ 



The mycelium appeared to emit light best when grown on bread 

 (1 part bread, 4 parts water), but it is also luminous when grown on 

 oatmeal agar or malt agar. The display of luminescence continues 

 steadily both day and night so long as the mycelium is actively 

 growing and only ceases when the mycelium has become old and 

 exhausted. The colour of the light may be described as pale 

 bluish-white. 



As in Panus sfypticus lurninescens,^ shadow photographs can be 



OMPHALIA 



FLAVIDA 



Fiu. 22:{. — A shaciow-photograpli of the black-paper letters of the words om- 

 rn.\L[.'V FLAVIDA made with tlie light of the mycelium of OmphdUa flavida 

 growing on an agar medium in a Petri dish 7 cm. in diameter. Tlie negative, 

 covei'ed by a glass plate bearing the black-paper letters, was exposed for 

 12 hours at a distance of 10 cm. from the Petri dish. Photograph made for 

 the author by H. H. Thornbury. Reproduced the original size. 



made with the light emitted by the mycelium of Omplialia flavida, 

 and one such photograph, kindly made for me by Mr. H. H. 

 Thornbury of the University of Minnesota, is reproduced in Fig. 223. 

 The mycelium was grown on an agar medium in a Petri dish 7 cm. 

 wide. The negative, covered by a sheet of glass to which the 

 black-paper letters OMPHALIA FLAVIDA were attached, was 

 exposed for 12 hours at a distance of 10 cm. from the Petri dish. 



1 In 1927, whilst visiting the Imperial Mycological Institute at Kew, by making 

 use of some of Mr. Ashby's cultures I was able to demonstrate the bioluminescence 

 of the mycelium of Omphalia flavida to Mr. Ashby himself. 



2 These Researches, Vol. Ill, 1924, pp. 388-390, Figs. 168-169. 



