The legendary serpent-stone is usually one taken from the reptile’s head, but Welsh tradition tells of one extracted from the tail of a serpent by the hero Peredur, and having the magic property that anyone holding it in one hand would grasp a handful of gold in the other. This stone was generously bestowed upon Etlym by the finder, who only secured it after vanquishing the serpent in a dangerous conflict.[452] The snake-stone (or “madstone”), in Arabic _ḥajar alḥayyat_, is described by the Arab writer Kazwini, as being of the size of a small nut. It was found in the heads of certain snakes. To cure the bite of a venomous creature the injured part was to be immersed in sour milk, or in hot water, and when the stone was thrown into the liquid it would immediately attract itself to the bitten part and draw out the poison.[453] The homeopathic idea plays a considerable rôle in the superstitions of the Arabs of northern Africa. To cure the bite or sting of the scorpion, the creature is to be crushed over the wound it has inflicted. If anyone is bitten by a dog, he should cut off some of the animal’s hair and lay this on the bitten part; if, however, the dog was mad, it must be killed, its body opened and the heart removed. This is then to be broiled and eaten by the person who has been bitten.[454] Many beautiful glass beads of Roman, or perhaps of British fabrication, have been found in Great Britain and Ireland. Upon some of these are bosses composed of white spirals, the body of the bead being blue, red, yellow, or some other brilliant color. These have been called “holy snake beads.” Probably most of them are merely ornamental productions and were not intended to represent serpent-stones. The curious test of the genuineness of an _ovum anguinum_ mentioned by Pliny, namely, that even if set in gold, it would float up a stream against the current, indicates a very porous structure; perhaps some of these serpent’s eggs were hollow, vitrified clay balls with wavy lines on the surface. De Boot, in his treatise on stones and gems,[455] figures the _ovum anguinum_, and says that its form was either hemispherical or lenticular. In his opinion the name “serpent’s egg” was given to the stone because on its surface there appeared five ridges, starting from the base and tapering off toward the top. These bore a certain resemblance to a serpent’s or adder’s tail. The stone was believed to protect the wearer from pestilential vapors and from poisons.