The ancient Romans believed in the existence of a crystalline stone which they called alectorius, as large as a bean, and to be found in the gizzard of a cock, though not by any means, discoverable in every fowl cut open. This stone was held to have the wonderful property of rendering the human possessor of it invisible. It may indeed have had the same effect on the original owner, as there could scarcely be an authentic instance of a stone of such peculiar property being found, but if the fowl itself could not be seen it is scarcely to be wondered at that the stone within it should be equally invisible. The belief in some such stone was one of the numerous articles of faith of the Middle Ages, but instead of the property of invisibility being attached to its possessor they sometimes substituted for it the much more prosaic idea that its owner could never feel thirsty, while the way to discover the bird that possessed it was simplicity itself, it being only necessary to discover which fowl at feeding time never drank. The first belief is much the more tenable, and is in fact impossible of refutation, as the world may be full of the owners of alectorius, invisible to us, and therefore unknown. The cock was at one time supposed to possess the power of laying eggs from which were reared the deadly cockatrice. “When the cock is past seven years old an egg grows within him, whereat he greatly wonders. He seeks privately a warm place, and scratches a hole for a nest, to which he goes ten times daily. A toad privily watches him, and examines the nest every day to see if the egg be yet laid. When the toad finds the egg he rejoices much, and at length hatches it, bringing forth an animal with the head, neck, and breast of a cock, and from thence downward the body of a serpent.”[87] In the year 1474 a cock at Basle was publicly accused of having laid one of these very objectionable eggs, and after a short trial[88] was sentenced to death and burnt, together with the egg, in the market place, amid a great concourse of the towns-folk, who were right joyfully thankful to feel that a great peril had been averted by the prompt action of their rulers, for a cockatrice was indeed no laughing matter to those who thought it one of the possibilities of life. In England the hens have entirely usurped the egg-laying department, and we are therefore spared the mortification of finding that our hoped-for chick has assumed the less welcome form of a cockatrice.