Shining Fish, Flesh, and Wood 489 



the firefly, coming to the conclusion that the light of all resulted 

 from a slow burning quite comparable to the combustion connected 

 with the respiration of animals. He believed that during the putrid 

 fermentation of the wood, its hydrogen and carbon come more 

 readily into contact with oxygen of the air. The reason that every 

 kind of rotten wood is not luminous is because " the quantity of 

 hyrogen and carbon necessary to make a visible light is not pro- 

 duced." Despite Spallanzani's demonstration in 1767 that no small 

 organisms arose de novo in sterile culttn-e media, he overlooked the 

 luminous organisms on meat and wood. 



At almost the same time (1798) Carradori (1758-1818), a pro- 

 fessor at Pisa, had been studying the glowworm and had come to 

 the conclusion that the light depended solely on the will of the 

 insect.*^ He criticized Spallanzani's work on luminous wood in a 

 letter *- to Fabroni, saying that phosphorescent wood will luminesce 

 under water, oil and in the vacuum of a barometer and consequently 

 cannot be a slow combustion. He suggested that perhaps something 

 from the phosphorus had affected the wood in Spallanzani's experi- 

 ments with gases, because Spallanzani had placed both phosphorus 

 and wood together in the same chamber. Moreover, Carradori held 

 that glowworm luminescence occurred under water and oil, and 

 could not be due to the use of dissolved oxygen, because if that 

 were true, phosphorus should also light under water, which it did 

 not. 



Although some of Carradori's criticisms were reasonable and some 

 of his arguments seem justified, Spallanzani was correct. In fact his 

 views on " spontaneous phosphorescence " were decidedly modern. 



NICHOLAI TYCHSEN 



Tychsen (1751-1804), an apothecary of Kongsberg in Norway, 

 later living in Copenhagen, used the wood of fir trees which had 

 lain in the earth many years for experiments in 1797. He noted that 

 the wood luminesced under water. It lost its light when dry and 

 would not luminesce when again moistened if dried for too long a 

 time. The light also disappared when the wood was crushed be- 

 tween the fingers. Tychsen was particularly interested in compar- 

 ing luminous wood and phosphorus, which had been studied by 

 Gottling (1795) . In general, the two were found to be rather simi- 



*^ According to Brugnatelli (Gilbert's Ann. der Physik 4:442, 1800), Carradori 

 thought the light of the firefly and rotten wood was like that of a phosphor, i. e., due 

 to absorption of light. 



"Carradori, Annates de Chemie 24: 216-225, 1797; translated in Phil. Mag. 2: 77-80, 

 1798, and Annalen der Physik 1:205-213, 1799. 



