4i6 RESEARCHES ON FUNGI 



remain to be precisely determined. Up to the present, my obser- 

 vations all point to the conclusion that P. stypt. luminescens is 

 widely spread throughout North America and does not occur in 

 England, and that P. stypt. non-luminescens is found in England 

 and does not occur in North America. Since luminous fruit-bodies 

 of Panus stypticus have never been recorded by any European 

 mycologist, it seems extremely probable that P. stijpt. non-lumin- 

 escens is not confined to England but occurs throughout Europe. 

 Possibly its distribution is Eurasian in extent. It seems most 

 likely that one of the two physiological forms arose from the other 

 and that to-day they are separated geographically because the great 

 barrier of the Atlantic Ocean prevents their interminghng. 



Luminous and Non-luminous Forms of Xylaria Hypoxylon.— 

 There seems to be no special reason why there should not be as 

 many luminous Ascomycetes as Hymenomycetes ; but, up to the 

 present, the only ascomycetous genus in which bioluminescence has 

 been observed is Xylaria. 



In 1874, Ludwigi asserted that the mycehum of Xylaria 

 Hypoxylon (Fig. 177) contained in rotting wood obtained from 

 stumps is luminous ; and, in 1881, Crie,^ apparently without know- 

 ing of Ludwig's paper, made a similar claim for X. polymorpha 

 (Fig. 178). However, in 1904, Molisch,^ after studying X. Hypo- 

 xylon and X. Cookei in pure cultures, was unable to confirm 

 Eudwig's and Crie's observations : he grew X. Hypoxylon in pure 

 cultures for four years ; but, during all this time, neither the 

 mycelium nor the fruit-bodies ever gave out the faintest trace of 

 light. He therefore came to the conclusion that Ludwig and Crie 

 had probably been mistaken in the identification of the mycehum 

 which they had had under observation. 



In 1907, Gueguen,^ apparently without knowing of the observa- 

 tions of Molisch, published an account of the biology and anatomy 



1 F. Ludwig, Ueber die Phosphorescenz der Pilze und des Holzes, Inaugural 

 Dissertation, Berlin, 1874. 



2 L. Crie, " Sur quelques nouveaux cas de phosphorescence dans les vegetaux," 

 Compt. Rend., 1881, p. 853. 



3 Hans Molisch, Leuchtende Pflanzen, Jena, 1904, pp. 40-44. 



■* M. F. Gueguen, " Recherches biologiques et anatomiques sur le Xylaria 

 Hypoxylon," Bull. Soc. Mycol. France, T. XXIII, 1907, pp. 197-198. 



