If the Glow-worm possessed no other talent than that of chloroforming his prey by means of a few tweaks as gentle as kisses, he would be unknown to the world in general. But he also knows how to light himself like a lantern. He shines; which is an excellent manner of becoming famous. In the case of the female Glow-worm the lighting-apparatus occupies the last three divisions of the body. On each of the first two it takes the form, on the under surface, of a wide belt of light; on the third division or segment the bright part is much smaller, and consists only of two spots, which shine through the back, and are visible both above and below the animal. From these belts and spots there comes a glorious white light, delicately tinged with blue. The male Glow-worm carries only the smaller of these lamps, the two spots on the end segment, which are possessed by the entire tribe. These luminous spots appear upon the young grub, and continue throughout life unchanged. And they are always visible both on the upper and lower surface, whereas the two large belts peculiar to the female shine only below the body. I have examined the shining belt under the microscope. On the skin a sort of whitewash is spread, formed of some very fine grain-like substance, which is the source of the light. Close beside it is a curious air-tube, with a short wide stem leading to a kind of bushy tuft of delicate branches. These branches spread over the sheet of shining matter, and sometimes dip into it. It is plain to me that the brightness is produced by the breathing-organs of the Glow-worm. There are certain substances which, when mixed with air, become luminous or even burst into flame. Such substances are called combustible, and the act of their producing light or flame by mingling with the air is called oxidisation. The lamp of the Glow-worm is the result of oxidisation. The substance that looks like whitewash is the matter that is oxidised, and the air is supplied by the tube connected with the Glow-worm’s breathing-organs. But as to the nature of the shining substance, no one as yet knows anything. We are better informed as regards another question. We know that the Glow-worm has complete control of the light he carries. He can turn it up or down, or out, as he pleases. If the flow of air through the tube be increased, the light becomes more intense: if the same air-tube, influenced by the will of the animal, stops the passage of air, the light grows fainter or even goes out. Excitement produces an effect upon the air-tube. I am speaking now of the modest fairy-lamp, the spots on the last segment of the Glow-worm’s body. These are suddenly and almost completely put out by any kind of flurry. When I am hunting for young Glow-worms I can plainly see them glimmering on the blades of grass; but should the least false step disturb a neighbouring twig, the light goes out at once and the insect becomes invisible.