424 RESEARCHES ON FUNGI 



out whether or not luminous leaves occur in North America. 

 Whilst resident in England during the summer and autumn of 

 1922, I therefore wrote to several botanists in Canada and the 

 United States requesting them to look for such leaves and report 

 to me the results of their investigations. The reports which my 

 correspondents were good enough to send prove that the pheno- 

 menon of bioluminescence in decaying leaves undoubtedly occurs 

 in the United States. 



Dr. E. M. Gilbert of the University of Wisconsin investigated 

 rotting leaves in the neighbourhood of Madison (Wisconsin) and 

 reported as follows : 



" During the early part of September we had several days when 

 rainfall was sufficient to moisten thoroughly the soil in our denser 

 woods. On September 14 and again on September 15, I made 

 collections of leaves as suggested and placed them on a bench in 

 one of our dark-rooms. Returning to the room after a few minutes, 

 I saw that there was a distinct emission of light from certain of the 

 collections. So much light was given off that five of the nine lots 

 could be easily located. I picked out from each lot the leaves 

 which were luminescent and took them into dayhght. I then 

 found that almost all of them were oak leaves." 



Miss Louise Dosdall of the University of Minnesota investigated 

 rotting leaves at the University Farm, St. Paul (Minnesota), and 

 reported as follows : 



" On July 7, I went into an oak wood just off the Agricultural 

 College campus and filled a vasculum with moist decaying oak 

 leaves. The upper leaves were dry and I discarded them, taking 

 only the moist well decayed ones below. These were firm and still 

 recognisable as oak leaves, although many of. them broke when 

 handled. White spots and heavy mats of fungus hyphae were 

 common on the leaves. 



" After dark, I examined my booty in the laboratory and found 

 many of the leaves beautifully luminescent. In some leaves only 

 the petioles or mid-ribs gave out light, but in others there were 

 large luminescent spots. By marking the spots in the dark, I found 

 that it was always the greyish-white spots on the leaves which 

 were luminescent and 'that the heavy mats of white mycelium 



