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incipient decomposition. Decaying wood, under peculiar 

 conditions of temperature and humidity, evolves light ; and 

 it is well known that accumulated masses of vegetable mat- 

 ter, when not sufficiently dried, undergo fermentation, and, 

 if the process be not interrupted, evolve light and caloric, 

 and are destroyed by combustion. In recently dead animal 

 matter the phenomena of phosphorescence is most strikingly 

 exhibited. Soon after death, fishes become exceedingly lu- 

 minous. In burial grounds luminous appearances have 

 often been seen, and fearful and awful are they to the eye 

 of superstition. These corpse-lights, as they are called, are 

 clearly traceable to the same source, and take place during 

 the earlier stages of disintegration. A very curious, though 

 not very pleasing appearance of the same kind, and arising 

 from the same causes, has been observed by many in dis- 

 secting rooms. The ignis fatuus also is a phenomenon, 

 which, hke those already alluded to, is produced by electri- 

 city, the result of chemical action in decaying vegetable 

 matter, when the temperature is in neither extreme, and 

 humidity sufficient to lend its aid in producing the effect. 



Sir H. Marsh then proceeded to the consideration of 

 phosphorescence, as a function in living vegetables, and de- 

 scribed the extraordinary and brilliant appearance of phos- 

 phorescent lichens in the coal mines near Dresden. He 

 also stated that the flowers of several plants, in serene and 

 warm summer evenings, disengage light. 



It is now known with certainty that light is developed in 

 living animals, a large proportion of which are inhabitants 

 of the sea, and from their presence in the water arises the 

 phosphorescence of the waves, especially in the track of 

 sailing vessels. The author here enumerated and described 

 many of the most remarkable marine species of phosphores- 

 cent animals, and stated that luminous appearances had also 

 been observed in fresh water animalcula. 



He remarked the analogy betweeen luminous and electri- 



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