94 PHOSPHORESCENCE IN 



cence recommences when the temperature is gra- 

 dually raised again above this point. If the plant 

 has been kept for some time at freezing-point, 

 it loses its phosphoric property completely. A 

 warmth of +48 to +50 likewise destroys this 

 peculiar property. In other respects the emission 

 of light by this agaric is the same under water 

 as in the air, and pure oxygen does not appear to 

 augment its intensity. No elevation of tempera- 

 ture can be observed in the parts of the fungus 

 which shine. 



The phosphoric light emitted by Agaricus ole- 

 arius is evolved from the head (pileus) of this 

 fungus : the lamellce of the pileus, where the spo- 

 rules or seeds are accumulated, are the seat of 

 this extraordinary phenomenon. 



The byssoid fungi, which penetrate the tissues 

 of other superior kinds of fungi, or into decayed 

 wood, are frequently seen to'be phosphorescent, 

 and the light observed is generally attributed to 

 the decayed wood itself. This is very remarkable 

 in old willows (Salix). Wood which is tender, like 

 that of these willows, is often penetrated in all its 

 parts by filaments of the mycelium of some infe- 

 rior byssoid fungus, by which it acquires a pe- 

 culiar fungoid smell, and becomes luminous in 

 the dark. 



This light is curious to observe under the mi- 

 croscope, in a dark room. 



