224 History of Luminescence 



luzeau; the fiery yellow flowers of Tropaeolum, Calendula, etc. 

 Treviranus realized that most of the plant phosphorescences involved 

 light reflections and that only the subterranean rhizomorphs lumi- 

 nesced when living. Among vertebrates such luminous phenomena 

 as the eggs of lizards, the breast of an American heron," the urine 

 of skunks, sweat, and the eyes of various animals were classed as true 

 luminescences, although Treviranus (1832) cited Prevost (1810) 

 and Esser (1826) , who thought the glow of vertebrate eyes to be a 

 reflection. The luminescence of wood, roots, and flesh were con- 

 sidered in the section on dead animals and plants. 



In 1818 Treviranus concluded that light production had no direct 

 relation to life. Although higher animals can produce heat, it is 

 only the lower animals (and a few plants) that produce light. In 

 some insects the light appears to have a use in mating but not 

 among zoophytes. The luminous material is mostly excreted, like 

 urine or comes from skin glands. By movement and the access of 

 air the phosphorescent material is increased, an act dependent on 

 the will of the animal. " There is always some material, sometimes 

 local, sometimes over the whole body, from which the light comes, 

 that has the property of a true phosphorus," i. e., the element phos- 

 phorus, which luminesces in the air. 



In his second book (1832) , Treviranus again restated his opinion 

 that the luminescence came from phosphorus or a material contain- 

 ing phosphorus, but was under the control of vital processes. Lumi- 

 nescence required the respiration of the animal, especially in fire- 

 flies, and also secretion, both of which are life processes. He con- 

 sidered the fact that sea fish and wood produce luminous material 

 by a sort of decomposition to be evidence for the secretory origin 

 of animal light and suggested that the human cases of spontaneous 

 combustion might be due to phosphoretted hydrogen. 



CHRISTIAN GOTTFRIED EHRENBERG 



By far the most complete record of bioluminescence is to be found 

 in C. G. Ehrenberg's (1795-1876) monumental work of 161 pages, 

 "Das Leuchten des Meeres," published in the Abhandlungen der 

 Koniglichen Akademie der Wissenschaften at Berlin in 1834. The 

 monograph includes much more than phosphoresence of the sea. 

 In addition to his own observations, Ehrenberg mentioned every 

 known writer (435 names and many more references) on lumines- 

 cence of plants and animals from Aristotle to Johannes Miiller 

 (1834) , and gave a table of all known luminous forms with the 



'^London's Mag. Nat. Hist. 2:64, 1829, a letter from Philadelphia, confirmed by 

 Mr. Franklin Peale, proprietor of the Philadelphia Museum. 



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