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 hght 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 hght emitted by Agaricus ole- 
arius 1s evolved from the head (pileus) of this 
fungus: the lamella 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. 
