420 RESEARCHES ON FUNGI 



light and, if kept damp, continued to give out light for several 

 weeks. Afterwards, in Germany, he found that bioluminescence 

 was frequently exhibited by rotting leaves of the Beech {Fagns 

 silvatica). Oak {Quercus), Hornbeam {Carpinus Betulus), and Syca- 

 more {Acer Pseudoplatanus). A microscopical investigation proved 

 that those parts of the leaves which radiated light contained a weft 

 of brown or colourless fungus hyphae. The emission of Hght by 

 dead leaves was therefore attributed by Molisch to fungi. The 

 identification of the species concerned was attempted by Molisch, 

 but unsuccessfully ; and this attractive problem, which involves 

 the making of pure cultures and the development of fruit-bodies, 

 still remains unsolved.^ 



In giving directions as to the best means of finding luminescent 

 leaves, Molisch 2 says : " One should seek especially in those places 

 where' the leaves of the previous year and of earlier years lie in a 

 thick layer about 10-30 cm. (4-12 inches) deep. The uppermost 

 leaves are mostly dry, brown, and of a firm consistence. Under 

 these there is often a zone of leaves which are like the leaves of a 

 book in that they he flattened one upon the other, although irregu- 

 larly. These leaves are already in an advanced state of decay and 

 are distinguished by their more yellow or whitish-yellow colour 

 which can be seen throughout the whole leaf or only in spots. . . . 

 It is chiefly the bright spots standing out on the deeper brown of 

 the leaves which give out Ught, and their presence indicates the 

 degree of decay which is most favourable for luminescence. If one 

 collects a few handfuls of such leaves, one can be sure that at night 

 one will be able to observe them glowing with a Hght which is more 

 or less clear and not infrequently splendid." 



To the above Mohsch ^ adds the following remarkable state- 

 ment : " Now that I have known the phenomenon (of the lumi- 

 nescence of decaying leaves) for five years and have assured myself 

 of its general prevalence I can say, without fear of exaggeration, 

 that in an Oak wood or Beech wood a by no means inconsiderable 



1 I have seen fungus hyphae in luminous leaves but, doubtless, they are accom- 

 panied by numerous bacteria. Whether the luminescence is caused by fungi or by 

 bacteria seems to me to be as yet an open question. 



2 Hans Molisch, Leuchtende Pflanzen, Jena, 1904, pp. 50-51. 



3 Ibid., p. 51. 



