There are many varieties among the forms of life that emit from their surfaces and various parts of their bodies a powerful luminosity, and are called phosphorescent. It has been supposed by some naturalists to be the result of electrical action, and by others as the result of a peculiar construction of the part giving out the light, so that it will absorb a greats quantity of light from the surrounding media in which they live. Both of these may be true in regard to different species of animals. Most of the luminous beings belong to the invetebrate classes, and frequently render vast portions of the ocean, one sea of fire, by their prodigious numbers. The most common are the glowworm, the phosphorescent sea-pen, and the brilliant pyrosome, usually found in the Atlantic's rolling waves.