PANUS STYPTICUS LUMINESCENS 411 



physiological form of Panus stypticus, which I call P. stypt. non- 

 luminescens, give out no Hght whatever. 



In the autumn of 1923, with the assistance of correspondents, 

 I assembled five collections of fruit-bodies of Panus stypticus, two 

 from England (West Malvern, Great Missenden) and three from 

 North America (Ottawa, Ann Arbor, St. Paul), and revived the 

 fruit-bodies at one and the same time. The fruit-bodies all resumed 

 their activities and shed an abundance of spores ; but, whereas the 

 three collections from North America became luminous, the two 

 collections from England remained non-luminous. The result of 

 this comparative experiment adds further strength to the view that 

 there are two distinct physiological forms of Panns stypticus, one 

 in North America having luminous fruit-bodies and another in 

 England having non-luminous fruit-bodies. 



As we have already seen, in Panus stypt. luminescens the 

 mycelium, shares with the fruit-bodies the property of emitting 

 light. It now remains to add that in Panus stypt. non-luminescens 

 the myceHum resembles the fruit-bodies in being entirely non- 

 luminous. 



The fact that, in Panus stypticus, a mycelium of North American 

 origin is luminous, whereas a mycelium of English origin is non- 

 luminous was demonstrated in one series of experiments as follows. 

 Blocks of Birch wood were sterilised in glass sealing- jars in the 

 manner already described. Some of the blocks were then inocu- 

 lated with spores from a spore-deposit of North American origin 

 and other blocks were inoculated with spores from a spore-deposit 

 of EngHsh origin. The spores germinated and produced myceha 

 which in the course of a few weeks grew down over the surface of 

 the wood (Fig. 170, p. 391, and Fig. 175). By examination of the 

 jars in a dark room on many separate occasions in the course of a 

 year it was found that every mycelium of North American origin 

 was luminous, while every mycelium of English origin was non- 

 luminous. 



The lack of luminosity in a mycelium of EngUsh origin was 

 further proved by photographic means. An attempt was made to 

 take a photograph of a fern leaf with Enghsh mycelium, using 

 precisely the same method as, with North American myceHum, was 



