STUDIES ON THE LUMINOUS FUNGS. 7 



decaying mass of certain fungi, which luminous matter could be 

 spread over a trunk of tree ; but, as a matter of fact, its real 

 nature has not been accurately determined. Several species of 

 fungi other than those referred to above are believed to be of a 

 luminous nature, but in most of these cases we have no trust- 

 worthy record of experimental researches. Apparently the lumi- 

 nous parts differ in different species of fungi ; and even as regards 

 the same species different observers have maintained different views 

 on the point. In the new fungus studied by me the luminosity is 

 restricted to the fruit-body. The mycelia found on and in the 

 decayed beech trunk are never luminous. The light is uniformly 

 emitted all over the region of the gills only. It never appeared 

 spotwise except where the gills had been injured. 



The fungus commences to emit light at a stage of its growth 

 when the gills have become fully expanded. The light dies out 

 gradually as the plant becomes old. The fading away takes place 

 uniformly in all parts of the gills. The free edge of gills is very 

 thin, while its base is massive and may well be compared to the 

 back of a knife-blade. In relation with that fact, the light re- 

 mains for a long time at the bases of gills after it has faded at 

 the thin edge ; and in old specimens of the fungus some non- 

 luminous lines are seen radiating from the stem toward the cir- 

 cumference of pileus. 



The next problem was to determine from what part or parts 

 of the gills the light is emitted. Delile 1 * and some other authors 

 have maintained that the luminosity originates in the hymenium. 

 But there still remained undetermined the question, if it is the 

 hymenium alone that emits light, and if the trama between 

 hymenia does not participate in the emission. This uncertainty 

 stands in relation to the feebleness of the light, on which account 



1) Delile, Nouv. exam. de la phosph. de l'Ag. de l'Olivier. 



