PANUS STYPTICUS LUMINESCENS 397 



japonicus was plunged into a jar containing either hydrogen or 

 pure nitrogen gas, the emission of light ceased in the course of 

 a few minutes. He also found that the fruit-body recovered its 

 luminescence when it was again given access to the oxygen of 

 the air. 



For investigating the effect produced upon the luminescence of 

 Panus stypt. luminescens by replacing the air surrounding a fruit- 

 body by hydrogen I made use of the apparatus shown in Fig. 172. 

 The hydrogen M-as generated by the action of hydrochloric acid 

 upon zinc in the Kipp apparatus a ; and the passage of the gas 

 through the wash-bottle c and through the experimental tube e 

 was controlled by the stop-cock 6. In order to prepare for an 

 experiment, the tap b was opened and hydrogen was allowed to 

 flow through the wash-bottle (containing water) and the experi- 

 mental tube until all the air had been completely driven out of 

 the apparatus. The tap d was then closed. Next, the rubber 

 stopper h was pulled out from the end of the experimental tube so 

 as to allow the hydrogen in the tube to escape and be replaced by 

 air. Then two luminous fruit-bodies g were inserted into the end 

 of the tube, as shown in the illustration, and the stopper h was then 

 put back into place. The electric light of the dark-room in which 

 the apparatus was set up was now switched off. I waited for a 

 few minutes until the sensitiveness of my eyes to light had greatly 

 increased and I could clearly see the glow coming from the under 

 surfaces of the two fruit-bodies. Then the tap d was turned on, 

 thus allowing the hydrogen gas to rush through the experimental 

 tube e and drive out the air which it contained. 



Immediately after the hydrogen gas was allowed to flow through 

 the tube e, the light of the fruit-bodies began to grow dim, and 

 within three seconds of turning on the tap d every trace of lumin- 

 escence had vanished. Shortly after the fruit-bodies had ceased 

 to emit light, the taps * and d were closed in succession. The 

 hydrogen surrounding the fruit-bodies thus came to be imprisoned 

 in the tube e. So long as the tube contained hydrogen, the fruit- 

 bodies never emitted any light whatever. After the fruit-bodies 

 had remained in the hydrogen for 5 minutes, trial was made of the 

 effect of suddenly giving them access to the oxygen of the air. 



