BIOLUMINESCENCE OF DECAYING LEAVES 425 



emitted no light whatever. The light was pale white. I picked 

 out at least twenty leaves with luminescent spots, and the light 

 from some of the larger ones was sufficiently strong to enable me 

 to see the outline of my hand. 



" I was so pleased with the results that on July 11 I gathered 

 several vasculums full of oak leaves from the same woods and gave 

 a demonstration of the phenomenon at the close of our literature 

 seminar. On this occasion we found a great many luminescent 

 leaves and, as before, the light seemed to come from the greyish- 

 white spots. We also found growing among the leaves many rhizo- 

 morphs, and these gave off a brighter light than the leaf-spots. 



" From these two trials, I can assure you that luminescent oak 

 leaves are very common here. They are indeed so common that 

 everyone has been wondering why he had not discovered them for 

 himself long ago." 



The above reports of Dr. Gilbert and of Miss Dosdall prove in 

 the most convincing manner that the bioluminescence of decaying 

 leaves is a common phenomenon in certain woods in the United 

 States. 



The reports from my Canadian correspondents were all negative. 

 Those who failed to find luminous leaves in Canada were as follows : 

 (1) Miss Irene Mounce and Mr. C. W. Lowe at Vancouver, British 

 Columbia ; (2) Mr. C. W. Lowe at Winnipeg, Manitoba ; (3) Dr. 

 Margaret Rioch at Kenora, western Ontario ; and (4) Mr. F. L. 

 Drayton at Ottawa, eastern Ontario. 



Mr. Drayton in eastern Ontario examined the following six 

 kinds of decaying leaves : (1) Yellow Birch, Betula lutea, (2) Iron- 

 wood, Ostrya Virginiana, (3) Sugar Maple, Acer Saccharum, 

 (4) Blue Beech, Carpinus caroliniana, (5) White Spruce, Picea 

 canadensis, and (6) White Oak, Quercus alba ; but in none of them 

 could he detect the least trace of luminescence. 



At Winnipeg, in the spring of 1923, I failed to find any luminous 

 leaves among Oak-leaf mould, but the absence of bioluminescence 

 may have been due (1) to the leaves of the previous autumn not 

 being sufficiently rotted and (2) to the leaves of the penultimate 

 autumn being rotted too much. The leaf-mould at Winnipeg is 

 very thin and therefore contrasts strongly with the thick leaf-mould 



