PANUS STYPTICUS LUMINESCENS 395 



have then recorded the time which elapsed between the moment 

 of wetting and the moment when I first perceived the emission of 

 hght from the gills. The following are the lengths of four of the 

 recovery -periods thus measured: (1) 6 minutes, (2) 5 minutes, 

 (3) 10 minutes, all for fruit-bodies kept dry for two to three months, 

 and (4) 8 minutes for some fruit-bodies kept dry for six months. 



When a luminescent fruit-body is allowed to dry up, it soon 

 ceases to shed spores, and then its outer edges curl downwards and 

 inwards as already described in an earlier Section. Light still 

 continues to be emitted after spore-discharge has ceased and even 

 when the curling-up process is far advanced. Comparatively little 

 water therefore seems to be necessary to permit of the photogen 

 being active. Light ceases to be emitted only after the fruit-body 

 has lost most of its water and is becoming dry and tough. When 

 a dried curled-up fruit-body is wetted, it begins to emit light almost 

 before the uncurling process has begun. 



A block of wood bearing Panus stypt. luminescens fruit-bodies 

 was removed from a stump of a tree and set in a bottle like that 

 shown in Fig. 170 (p. 391). After a few weeks some new fruit- 

 bodies grew out from the block. Two of them developed quite 

 normally and, as usual, were brightly luminous. Owing to de- 

 ficient water-supply from the wet cotton wool beneath the block, 

 one of the fruit-bodies curled downwards and inwards, dried up, 

 and ceased to be luminous. The other one grew so that its upper 

 surface came to be applied to the surface of the wood of the some- 

 what moist block. Under these conditions its pileus did not curl 

 downwards and inwards, but remained flattened and continued to 

 give out light from its under surface for three months. Now it had 

 been observed that fruit-bodies severed from their substrata and 

 placed on wet cotton wool in a damp-chamber give out light for only 

 about 7—10 days. It was therefore surprising to find that the 

 fruit-body just described, after becoming full-grown, continued to 

 emit light for three whole months.^ To account for this relatively 

 very long luminescent period we may suppose that the fruit-body 



1 Actually 87 days. At the end of this period the fruit-body was still emitting 

 light feebly, but owing to my departure from Winnipeg, I could make no further 

 records. 



