396 RESEARCHES ON FUNGI 



contained too little water to enable its hymenium to undergo rapid 

 development and exhaustion, and yet enough water to permit of 

 the continuance of the oxidative process which results in the emission 

 of light. Doubtless, if one were to take a partially dried fruit-body 

 and keep it in a damp atmosphere so that it could not dry up, it 

 would continue to give out light far longer than another similar 

 fruit-body which was fully saturated with water. 



Dependence on Oxygen. — Luminous fungi, like all other luminous 

 organisms, only emit light in the presence of oxygen. This was 

 first proved by Robert Boyle,^ who experimented on the effect of 

 removing the air from a piece of luminous wood. It is probable 

 that the wood contained the mycelium of ArmiUuria mellea, for in 

 England this fungus, which has a luminous mycelium, is very 

 commonly found upon stumps and at the base of dead trees. 

 Boyle on October 29, 1667, thus described his experiments : 



" Exp. I. : Having procured a Piece of shining Wood, about 

 the bigness of a groat or less, that gave a vivid light (for rotten Wood), 

 we put it into a middle sized Receiver, so as it was kept from 

 touching the Cement ; and the Pump being set a-work, we observed 

 not, during the 5 or 6 first Exsuctions of the Air, that the Splendor 

 of the included Wood was manifestly lessened (though it was never 

 at all increased ; ) but about the 7th Suck, it seemed to glow a little 

 more dim, and afterwards answered our Expectation, by losing of 

 its Light more and more, as the Air was still farther pumped out ; 

 till at length about the 10th Exsuction, (though by the removal 

 of the Candles out of the Room, and by black Cloaths and Hats 

 we made the place as dark as we could, yet) we could not perceive 

 any Light at all to proceed from the Wood. 



" Exp. II. : Wherefore we let in the outward Air by Degrees 

 and had the pleasure to see the seemingly extinguished Light revive 

 so fast and perfectly, that it looked to us almost like a little Flash 

 of Lightning, and the Splendor of the Wood seemed rather greater 

 than at all less, than before it was put into the Receiver." 



Kawamura^ observed that, when a fruit-body of Pleurotus 



1 Robert Boyle, Phil. Trans. Roy. Soc, Abridged, 5th Ed., vol. ii, 1722, p. 206; 

 and vol. iii, 1749, p. 646. 



^ S. Kawamura, loc. cit., pp. 19-21. 



