“Various theories were current among the peasantry to account for their existence. Some of them ascribed them to lightning; others to moles or other animals; and others again to the growth of a species of fungus. This is the more educated class. But the lower orders implicitly believed that they were the work of the fairies, and used by them for their nocturnal dancing. Woe to the poor mortal who ventured near at such moments. He was seized, forced to dance, soon lost all consciousness, and was truly in luck if he ever again succeeded in rejoining his mortal relatives.” A very exhaustive account of these Circles, and the superstitions in reference to them, is to be found in the third volume of Brand’s Popular Antiquities, London, 1854, article “Fairy Mythology,” p. 476 _et seq._ “The most clear and satisfactory remarks on the origin of fairy rings are probably those of Dr. Wollaston, Sec. R. S., printed in the second part of the “Philosophical Transactions” for 1807.... The cause of their appearance he ascribes to the growth of certain species of agaric, which so entirely absorbs all nutriment from the soil beneath that the herbage is for a while destroyed.”—(Idem, p. 483.) “In Northumberland, the common people call a certain fungous excrescence, sometimes found about the roots of old trees, Fairy Butter. After great rains, and in a certain degree of putrefaction, it is reduced to a consistency which, together with its color, makes it not unlike butter, and hence the name.”—(Idem, p. 493.) Lady Wilde’s work, already quoted, makes no reference to the employment of either mushrooms or mistletoe by the Irish peasantry. The mixing, in the popular imagination, of Fairies and Druids, of Fairy Circles and the Druid Circles, is noticed on p. 505, Brand, art. “Fairy Mythology.” Perhaps in all this there may be a vague reminiscence of a former use of the agaric in potions not very dissimilar to those still to be found among the Koraks and Tchuktchi. We read that this Witches’ Butter was associated with sorcery. It was believed in Sweden to have been “spewed up” by the cat which went with the witch.—(See Brand, “Popular Antiquities,” London, 1872, vol. iii. p. 7, article “Sorcery.”)