554 PHOSPHORESCENT FUNGI IN AUSTRALIA, 



one of the luminous fungi, measuring about 4 or 5 inches in 

 diameter. The result was that the plate was distinctly "fogged" 

 from the action of the light and was not so affected when exposed 

 without the fungus. The plate was masked with a leaf design, 

 leaving the centre part exposed. 



In some of the luminous bacteria the blue and violet rays of 

 the spectrum predominate, and they have consequently been pho- 

 tographed by their own light. B. Fischer has also demonstrated 

 that the light from streak cultures of these microbes is sufficiently 

 strong to illuminate and photograph adjacent objects, such as a 

 watch.* 



Supposed cause of the phenomenon. 



As a consequence of respiration or the combustion of carbon 

 compounds, heat is liberated in all living plants, but the develop- 

 ment of light only rarely takes place. As we have seen, only a 

 few fungi become luminous, and it is found that as the respiration 

 becomes feebler the light decreases in intensity and ceases 

 entirely at death. 



The production of light is also usually confined to certain 

 portions of the organism, and may occur either in the vegetative 

 portions or the fructification. In Armillaria mellea, for instance, 

 it is only the mycelial strands and the fine white threads per- 

 meating the wood of the trees on which it grows that emit the 

 light, so that the decaying wood among which they ramify is often 

 spoken of as luminous. In Plewotus olearius, on the other hand, 

 the entire fructification is luminous, consisting of stalk, pileus 

 and gills, while in others, such as the present one (P. candescens), 

 the gills alone are luminous. Although the luminosity is con- 

 fined exclusively in some cases to the vegetative organs and in 

 others to the organs of reproduction, still the distinction is not 

 absolute, for in the fungus under notice I found that the fresh 

 downy material at the base was also luminous. 



* Lafar. Technical Mycology, p. 164 (1898). 



