General Statement 



THE BURNING of the sca and the shining of wood, dead fish, and 

 flesh were well recognized phenomena in 1600, but the bio- 

 logical origin of the light was completely unknown. The existence 

 of cucujos, fireflies, glowworms, and luminous centipedes was an 

 obvious fact. Larger luminous sea animals, such as jellyfish, pid- 

 docks, and sea pens, indicated that living marine forms were capable 

 of emitting light, but it was over 200 years before the diffuse phos- 

 phorescence of the sea was universally ascribed to microscopic lumi- 

 nous organisms. A somewhat longer time was necessary to establish 

 the fact that phosphorescence of wood came from the luminous 

 threads of a fungus, or that glowing meat and dead fish had colonies 

 of luminous bacteria growing on them. Apart from some incorrect 

 cases of light production reported among higher plants,^ these fungi 



^ The following are the best known reports of false luminescence among plants. 

 The statement that Jean Senebier observed luminescence from the spadix of an arum 

 when placed in pure oxygen is incorrect. Senebier {Physiologie vegetal, 3: 315, Geneva, 

 1800) had found heat produced when the spadix opened in air and suggested there 

 might be phosphorescence in pure oxygen, but he never carried out the experiment. 



The phosphorescent milky latex of Euphorbia phosphorea, reported by von Martins 

 in Reise in Brasilien (2: 726, 746, 1828) might be explained as a reflection from heat 

 lightning, since the observations were made during a sultry evening (gewitterschwiilen 

 Abend). Molisch (1904: 153) was unable to observe any luminescence in the various 

 types of latex he examined. Another record of a luminous latex from Brazil, by A. F. 

 Mornay {Phil. Trans., 106, 279, 1816) could also be due to a dim light reflected 

 from the white liquid. The observation was made on the curious plant, " cipo de 

 cunanam," abundant between Monte Santo and the river Bendeg6, near Bahia. 

 Mornay wrote: " When I made a cut at the bush with my hanger, in the dusk of 

 the evening, the wounds inflicted presented a beautiful luminous line, which was not 

 transient, but lasted for several seconds or a quarter of a minute. Having taken a 

 piece of the plant, I bent it in the dark until the skin cracked, when every crack 

 showed the same light which is of a phosphorescent appearance. I continued to bend 

 the twig until the milky juice dropped out, when each drop was a drop of fire, very 

 much like what I have seen on dropping inflamed tallow. I did not observe any 

 particular smell." The statement is definite, but was made " in the dusk of the 

 evening," and hence the phenomenon cannot be designated as a true luminescence 

 with any certainty. 



Much has been written on the " flashing of flowers," since the light of the Indian 

 Cress (Tropaeolum majus) was described in 1762 by Elizabeth Christine von Linn^, 

 the daughter of Linnaeus (Kongl. Svenska Wetenscap. Acad. Handlingar, 284, 1762) . 

 This " glow " of yellow or orange flowers, observed in the early evening has been 

 considered an electrical phenomenon by Volta in 1799 {Meterologische Brieve 1:24), 

 and by Richard Pulteney in 1790 {Historical and biographical sketches of the progress 

 of botany in England I: 346) , whereas Goethe {Zur Farbenlehre 1: 21, 1810) called it 

 an illusion. Whatever the explanation of the flashing, there is no luminescence 

 involved. 



The European dittany, Dictamnus fraxinella, is said to evolve on inflammable gas 



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