PHOSPHORESCENCE OF PYROSOMA. 427 



fields of these molluscs, 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. Peron 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 

 tubercles, 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 



