104 Observations upon Luminous Animals. 
ations, so far from possessing phosphoric properties, is in= 
combustible, and loses the quality of emitting light, by 
being dried, or much heated.—The exhibition of light, 
however long it may be continued, causes no diminutions 
of the buik of the luminous matter. It does not require 
the presence of pure air, and is not extinguished by other 
gases. 
The luminous appearance of living animals is not ex- 
hausted by long continuance, or frequent repetitions, nor 
accumulated by exposure to natural light; it is therefore 
not dependent ‘upon any foreign source, but inheres as a 
property, in a peculiarly organized animal substance or 
fluid, and is regulated by the same laws which govern all 
the other functions of living beings. 
The light of the sea is always produced by living animals, 
and most frequently by the presence of the medusa scintil- 
lans. When great numbers of this species approach the 
surface, they sometimes coalesce together, and cause that 
snowy or milky appearance of the sea, which is so alarming 
to navigators. These animals, when congregated on the 
surface of the water, can produce a flash of light, somewhat 
‘ hike an electric coruscation. When the luminous meduse 
are very numerous, as freyuently happens in confined bays, 
they form a considerable portion of the mass of the sea, at 
which times they render the water heavier, and more nau- 
seous to the taste; it 1s therefore adviseable to always strain 
sea-water before it is drunk. 
The luminous property does not appear to have any con- 
nection with the ceconomy of the animals that possess it, 
excepting in the flying insects, which by that means dis- 
cover each other at might, for the purpose of sexual con- 
gress, 
Explanation of the Figures (Plates 1 and TI.) 
Fig. 1. The cancer fulgens, discovered by the Right Hon, 
Sir Joseph Banks, of the natural size. 
Fig. 2. The same animal magnified. 
Fig. 3. The medusa pellucens, also found by Sir Joseph 
Banks, represented of the natural magnitude. 
. Fig. 4. The limulas. noctilucus, discovered by Captain 
Borsburgh, considerably enlarged. 
* Fig. 5. The luminous medusa, discovered by me, which 
I conceive to be the medusa hemispherica; it is shown of 
the largest size I met with. 
_. Fig. 6. The central process of this animal’s body magni- 
fied, in order to-explain its structure. The thick tentaculg 
Heid in 
