PHOSPHORESCENCE OF PYROSOMA. 427 
fields of these molluses, floating and glowing as they floated on 
all sides of her course. Enveloped in a flame of bright phos- 
phorescent light, and gleaming with a greenish lustre, the 
Pyrosomes, in vast sheets, upwards of a mile in breadth, and 
stretching out till lost in the distance, presented a sight, the 
glory of which may be easily imagined. The vessel, as it 
cleaved the gleaming mass, threw up strong flashes of light, as 
if ploughing through liquid fire, which illuminated the hull, the 
sails, and the ropes, with a strange unearthly radiance. 
In his memoir on the Pyrosoma, M. Péron describes with 
lively colours the circumstances under which he first made its 
discovery, during a dark and stormy night, in the tropical 
Atlantic. “The sky,” says this distinguished naturalist, “was 
on all sides loaded with heavy clouds; all around the obscurity 
was profound; the wind blew violently, and the ship cut her way 
with rapidity. Suddenly we discovered at some distance a great 
phosphorescent band stretched across the waves, and occupying 
an immense tract in advance of the ship. Heightened by the 
surrounding circumstances, the effect of this spectacle was 
romantic, imposing, sublime, rivetting the attention of all on 
board. Soon we reached the illuminated tract, and perceived 
that the prodigious brightness was certainly and only attributable 
to the presence of an innumerable multitude of largish animals 
floating with the waves. From their swimming at different 
depths they took apparently different forms: those at the greatest 
depth were very indefinite, presenting much the appearance 
of great masses of fire, or rather of enormous red-hot cannon 
balls; whilst those more distinctly seen near the surface perfectly 
resembled incandescent cylinders of iron. 
“Taken from the water, these animals entirely resembled each 
other in form, colour, substance, and the property of phos- 
phorescence, differing only in their sizes, which varied from 
three to seven inches. The large, longish tubercles with which 
the exterior of the Pyrosomes was bristled were of a firmer 
substance, and more transparent than the rest of the body, and 
were brilliant and polished like diamonds. These were the 
principal scene of phosphorescence. Between these large 
tubereles, smaller ones, shorter and more obtuse, could be dis- 
tinguished; these also were phosphorescent. Lastly, in the 
interior of the substance of the animal, could be seen, by the 
