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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, like 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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