428 RESEARCHES ON FUNGI 



doubtless, its continuance is often interrupted by periods of 

 drought. 



Photographs made with the Light of Luminous Leaves. — Light 

 from the re-moistened luminous leaves just described was used for 

 making the shadow-photograph shown in Fig. 180. Some black- 

 paper letters making up the word LUX were stuck on to a clear 

 glass plate and this was placed in a j^rinting frame over a photo- 

 graphic plate, so that the letters pressed against the film. A small 

 crystallising dish containing about half a dozen luminous leaves 



Fig. 181. — A shadow-photograph of an Indian ink drawing on 

 a sheet of glass, made with the light emitted by luminous 

 Beech, Oak, and Spanish Chestnut leaves collected at Four 

 Oaks, Warwickshire, England. Exposure of negative, 50 

 hours. Original size. 



was placed in the middle of a much larger crystalhsing dish pro- 

 vided with a cover. The printing frame was then set as a cover 

 over the inner small crystallising dish in such a way that the sensi- 

 tive film was directed toward the luminous leaves. The distance 

 between the leaves and the film was about one inch. The plate 

 was exposed to the light of the leaves for 50 hours and then 

 developed. The negative yielded a print which is reproduced 

 in Fig. 180. When the exposure of the negative was reduced to 

 24 hours, the resulting print was good, but not so good as that 

 shown in Fig. 180. 



Another shadow-photograph made with the light of the 



