Page:Popular Science Monthly Volume 7.djvu/473

Rh lamp is obtained sufficient for ordinary household purposes, and travelers are said to fasten the insects to the toes of their boots, in order to illuminate the pathways at night. The light proceeds from four yellow spots upon the thorax, two of which are hidden by the wing-covers, unless the insect be in flight, when the brightness of the light is also increased by the quicker respiration caused by the motion. The luminous matter is more largely distributed than in the glowworm, and, if the segmentary rings of the abdomen be gently pulled asunder, the light may be seen shining through the semi-transparent skin of the interstices.

Two East-Indian species of luminous beetles are especially worthy of mention. In the island of Singapore, a Lampyris is found which shines with an intermittent light. The insects cluster among the foliage of trees where the ground is damp and swampy, and, in accordance with some strange instinct, flash out their lanterns simultaneously. At one moment the tree will be dotted with bright sparks, which a moment later will have disappeared, excepting two or three. The intervals of darkness are about a second in duration. At these times the insects appear to be settled upon the leaves, and, if they are disturbed, they dart out at random, flashing their lights irregularly, and at shorter intervals. Borneo produces a species of glow-worm which shines with a triple row of lamps. It has been found crawling among dead-wood and leaves, the first row of lights being placed along the back, and the second and third rows along the sides.

Turning to another class among the land Articulata, we may briefly mention the phosphorescence of the centipede and that of the earthworm. Both phenomena may be seen in England, but are more common on the Continent. The centipede, which is tawny brown in color, and scarcely exceeds the tenth of an inch in diameter, is about an inch and a half in length. It frequents out-houses and arbors, where it may sometimes be found crawling along the ground, and searching for the insects on which it feeds. The phosphorescent property resides in a fluid which it secretes, and with which it can moisten the whole of its body. The light becomes more brilliant when the animal is irritated, and, if the fluid be received upon the hand, it will continue luminous for some seconds. M. Audouin, a French naturalist, residing near Paris, was witness of a remarkable appearance which was caused by luminous centipedes. He was informed that there were "earthworms" in a field near his house, glowing like red-hot coals. On going to the place to see, he found merely a few luminous streaks here and there upon the ground; but, when a spade was brought, and some of the earth thrown up, a beautiful spectacle presented itself. Great numbers of centipedes, which had collected together for some purpose, were unearthed, and the soil shone with the light which they emitted, the streaks remaining visible for many seconds, if the clods were crushed beneath the foot. Similarly, Prof.