426 THE INHABITANTS OF THE SEA. 
Polar Seas are illuminated by its fairy light. “The nature 
of its luminosity,” says Dr. Carpenter, “is found by microscopic 
examination to be very peculiar; for what appears to the eye te 
be a uniform glow is resolvable under a sufficient magnifying 
power into a multitude of evanescent scintillations, and these 
are given forth with increased intensity whenever the body of 
the animal receives any mechanical shock.” 
The power of emitting a phosphorescent light is widely dif- 
fused both among the free-swimming and the sessile Ccelenterata. 
Many of the Physophoride are remarkable for its manifestation, 
and a great number of the jelly-fishes are luminous. Our own 
Thaumantias luciferu, a small and by no means rare medusid, 
displays the phenomenon in a very beautiful manner, for, when 
irritated by contact of fresh water, it marks its position by a 
vivid circlet of tiny stars, each shining from the base of a 
tentacle. A remarkable greenish light, like that of burning 
silver, may also be seen to glow from many of our Sertularians, 
becoming much brighter under various modes of excitation. 
Among the Ctenophora the large Cestwm Veneris of the 
Mediterranean is specially distinguished for its luminosity, and 
while moving beneath the surface of the water gleams at night 
like a brilliant band of flame. 
The Sea-pens are eminently phosphorescent, shining at night 
with a golden-green light of a most wonderful softness. When 
touched, every branchlet above the shock emits a phosphoric 
glow, while all the polyps beneath remain in darkness. When 
thrown into fresh water or alcohol, they scatter sparks about in 
all directions, a most beautiful sight; dying, as it were, ina 
halo of glory. 
But of all the marine animals the Pyrosomas, doing full 
justice to their name (fire-bodies) seem to emit the most vivid 
coruscations. Bibra relates in his ‘Travels to Chili” that he once 
caught half a dozen of these remarkable light-bearers, by whose 
phosphorescence he could distinctly read their own description 
in anaturalist’s vade-mecum. Although completely dark when 
at rest the slightest touch sufficed to elicit their clear blue-green 
light. During a voyage to India, Mr. Bennett had occasion to 
admire the magnificent spectacle afforded by whole shoals of 
Pyrosomas. The ship, proceeding at a rapid rate, continued 
during an entire night to pass through distinct but extensive 
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