PANUS STYPTICUS LUMINESCENS 393 



gave rise to numerous, small, somewhat abortive but luminous, 

 Panus stypt. luminescens fruit-bodies. 



The above observations clearly prove that, in Panus stypt. 

 luminescens, not only is the fruit-body luminescent but also the 

 mycelium. This emission of light in both the vegetative and the 

 reproductive stages of development is at present known to occur 

 in only one other luminous Hymenomycete, namely, Clitocybe 

 illvdens^ Kawamura^ states that, in Pleurotus japonicus, the gills 

 alone are luminous and that the pileus-flesh and the mycelium are 

 non-luminous. On the other hand in Armillaria mellea, as is well 

 known, the mycelium vegetating in the wood, the rhizomorpha 

 subcorticalis, and the developing rhizomorpha subterranea are 

 luminous ; but the fruit-body is non-luminous. 



A Photograph made with the Light of the Mycelium. — A shadow- 

 photograph of a dried frond of a fern was made with the light given 

 out by the mycelium of Panus stypt. luminescens in the following 

 manner. The fern leaf was held in a printing frame against the 

 film of a photographic plate by, means of a sheet of clear glass, and 

 then the frame was set as close as possible to the jar containing the 

 luminous mycelium. ^ After the plate had been exposed to the 

 light of the mycelium for 24 hours, it was developed ; and the 

 negative yielded the print which is reproduced in Fig. 171. A study 

 of the photograph shows that the light of the mycelium was suffi- 

 ciently strong to penetrate somewhat the whole thickness of the 

 leaflets except where these bore their black sori. 



Dependence of Luminescence on the Presence of Moisture. — 

 There can be no doubt that in fungi, as in animals, the emission 

 of light is dependent on the presence of moisture. In support of 

 this statement clear evidence can easily be obtained by making 

 experiments with Panus stypt. luminescen's. I found that dry 



^ W. A. Murril ("Luminescence in the Fungi," Mycologia, vol. vii, 1915, p. 132) 

 observed that the wood on which some fruit-bodies of C. illudens grew was luminous 

 in the dark and therefore concluded (p. 115) that the mycelium of C. illudens is 

 luminous. There is, however, the bare possibility that the mycelium in the wood 

 may have belonged to some other fungus, e.g. Armillaria mellea. It is therefore 

 desirable that some one should establish the luminosity of the mycelium of C. illudens 

 on the basis of pure cultures. 



^ S. Kawamura, loc. cit. 



^ The luminous mycelium had grown about to the extent shown in Fig. 175, p. 412. 



