3C8 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol. XVI. 



from a bunch of tuberoses on a dark hot night, and they have seemed to us to 

 partake of the nature of electric sparks. Of course, the light may have been 

 phosphorescent, but it is not improbable that, under the influences of heat and 

 electricity, combined with moisture, several tropical plants might exhibit a bril- 

 liant light. A writer in the Journal of Horticulture recalls an incident of some 

 sixty years ago when there was exhibited before the Royal Asiatic Society the 

 roots of a singular plant, presumably a species of Orchis, which grew amidst the 

 jungle below the Madura Hills, in India. It was phosphorescent, and even if 

 dried could be made to shine with the brightness of a glow worm when the 

 surface had a wet cloth applied for a short time. The editor of the Gardeners 

 Chronicle found that a small piece of this root retained its power of lighting up 

 a good while, only the light got feebler. The Brahmins, it was said, knew its 

 peculiarity but all the plants did not possess this luminosity at their roots. They 

 imagined the light of it drove away demons. Amongst the Himalayan hills the 

 natives describe slopes and valleys that are lighted up on damp nights by some 

 species of grass, as they think, possibly it is by crawling luminous insects. 



The same writer tells us that what is commonly known as " touchwood,' r 

 and, on account of its rapidly kindling property, is used for lighting fires, is 

 apt to be luminous. Schoolboys for generations have been in the habit of 

 carrying pieces of such wood into their dormitories to produce a sudden illumi- 

 nation at night. The wood of the Willow is specially notable for its readi- 

 ness to take fire. In the Northfleet Marshes, near Gravesend, the writer saw 

 numerous old Willows that had been almost stripped of bark, with the surface 

 of the wood blackened as if burnt. It would seem the wood was scorched by 

 a spark from some pipe, or by the fierce rays of the sun, but did not burn 

 away. Perhaps, since its luminosity can sometimes be developed by friction, 

 touchwood may retain heat, though we usually ascribe its brilliancy to phos- 

 phorescence. What is singular also, the sap of some trees in exotic regions 

 appears luminous, as it flows from a wound. One shrub, indeed, has been 

 named Euphorbia pliosphorea from this fact, and there are other instances. 

 We have it on the authority of the late Professor Henslow that the European 

 Dittany, Dictamnus fraxinella, evolves some inflammable gas in the evening, 

 and, should the air be still, if a light is brought near, the plant will be envelop- 

 ed in a transient flash, but receives no injury. Before his time the daughter 

 of Linnaeus had stated that a plant of D. alius, which she approached with a 

 candle, became surrounded by a light blue flame. Dr. Hahn suggested the 

 Dittany might produce hydrogen or evolve an ethereal oil from the flowers ; he 

 made many experiments amongst species of Dictamnus unsuccessfully, but at 

 last found a rather faded plant, from which, when he held a match, came a 

 reddish crackling flame, having an incenselike smell. Then he ascertained this 

 can only happen during the limited period of the flower's fading, and also that 

 there are glands containing an aromatic oil. A Himalayan species of the genus 

 has the reputation of making a brilliant display after dark, even when nob 

 approached by a light. 



