The light is extremely beautiful. That of the Atlantic forms is said to be polychroic, or an intense green; while in the very large species it is azure. So brilliant and striking is the light, that the impression is gained that it proceeds from the entire surface of the animal; but this is not the case, according to Panceri.[42] When the _Pyrosoma_ is moving along in its curious fashion,--which calls to mind the old stern-wheel steamers,--and is undisturbed, the light is intermittent, now flashing from one cell, and now from another; the vast number of gleams giving it the appearance at times of constant light over the entire surface. Panceri found that the luminous bodies produced an albuminoid substance that may become diffused by handling, and retain its luminosity for some time. Curiously enough, fresh water increases the intensity of the light, and causes it to continue for a longer period. The intensity of the light may be realized, when we learn from Figuier that Bibra, a Brazilian navigator, employed six _Pyrosomæ_ to illuminate his cabin, which was thus rendered so bright that he could read to a friend the description he had written of these living lanterns. Mr. Bennett, the naturalist, thus describes his experience with these beautiful creatures: “On the 8th of June, being then in latitude 30° south, and 27° 5′ west longitude, having fine weather and a fresh south-easterly trade-wind, and the thermometer ranging from 78° to 84°, late at night the mate of the watch called me to witness a very unusual appearance in the water. This was a broad and expansive sheet of phosphorescence, extending from east to west as far as the eye could reach. I immediately cast the towing-net over the stern of the ship, which soon cleaved through the brilliant mass, the disturbance causing strong flashes of light to be emitted; and the shoal, judging from the time the vessel took in passing through the mass, may have been a mile in length. On taking in the towing-net, it was found half filled with _Pyrosoma atlanticum_, which shone with a beautiful pale-greenish light. After the mass had been passed through by the ship, the light was still seen astern, until it became invisible in the distance, and the ocean became hidden in the darkness as before this took place.