Other luminous mushrooms abound in woods, swamps, and marshy areas. Decaying, they may produce an unearthly light and can give off a peculiarly unpleasant odor. Unexpectedly seeing and smelling a bird touched with the substance, on a dark night, a witness might well feel bewildered and even frightened. _Polyporus sulfureus_, which grows in dense masses on dead trees, often phosphoresces brilliantly in the early stages of its decay, as does _Clytocobe illudens_, the jack o’ lantern. In the tropics these fungi may produce enough light to read by. Birds, insects, and animals that brush against them can carry away some of the luminous material and thus, for a time, appear to be luminous themselves. Most of us recognize fireflies, lightning bugs, or glowworms--which are not worms but beetles. The wingless females must creep on the surface of ground or branch, but the winged males flit through the air. These sparkling creatures form part of the diet of birds and bats, and when carried aloft to be consumed in flight can make one more mysterious, swiftly moving light to frighten the apprehensive. The earth teems with other self-luminous organisms such as frogs’ eggs, which most of us have never seen and would not recognize. Luminous parasites sometimes live in the feathers of birds and make them glow. The plumage of the great blue heron, a North American bird, can emit a pale light sometimes known as the birds’s “lantern” because it is supposed to help him while fishing. Fish or meat when decaying can become infected with luminous bacteria and thus shine brilliantly in the dark. The sea is filled with phosphorescent fish and plants which help perpetuate tales of sea serpents. Some waters in the Caribbean contain so dense a population of phosphorescent algae that a bird, dipping its wings to snatch a meal, will glow for minutes after it soars again into the air. These luminous birds, innocently fishing for dinner, probably account for many reports that flying saucers come and go from underwater[VI-4]. Many of the erratically behaving UFOs observed at night over wooded areas, swamps, and marshes have undoubtedly been one of these will o’ the wisps--winged creatures glowing with borrowed fire. Unfortunately proof of this explanation is rarely possible. Before the startled observer can recover his wits the flitting “saucer” has gone, taking with it the evidence of its identity. Fear of the unknown is not confined to _Homo sapiens_. A news item published in England a few years ago reveals that the animal kingdom, too, may have its ghosts. Under the headline, _Owl Attacks Luminous Man_, the article reads: “A Bournemouth long-distance runner, Ken Baily, was attacked by an owl last night when he was running through the centre of Bournemouth in a luminous track suit. The bird ripped the front of his suit before it flew back into the trees.