In the north of Europe an opinion has long prevailed that the Swallows not only hybernate in a state of torpidity, but, like the frogs and toads, retire to the bottoms of pools to spend that dreary season. In Berger's "Calendar of Flora," published in the _Am{oe}nitates Academicæ_, vol. iv., he puts down as the phenomenon proper to the 22d of September, "_Hirundo submergitur_," talking, as Gilbert White remarks, as familiarly of the Swallows going under water, as he would of his poultry going to roost at sunset. Klein, and even Linnæus himself, adopted this strange opinion, which was considered to rest upon good testimony, and that not only of the illiterate and unobservant. Etmuller, who was Professor of Anatomy and Botany at Leipsig in the middle of the seventeenth century, says, "I remember to have found more than a bushel would hold of Swallows closely clustered among the reeds of a fish-pond under the ice, all of them to appearance dead, but with the heart still pulsating." And Derham, the acute author of "Physico-theology," citing this statement, adds, "We had at a meeting of the Royal Society, February 12, 1713, a further confirmation of Swallows retiring under water in the winter from Dr Colas, a person very curious in these matters, who, speaking of their way of fishing in the northern parts by breaking holes and drawing their nets under the ice, saith, that he saw sixteen Swallows so drawn out of the Lake of Lamrodt, and about thirty out of the king's great pond in Rosneilen; and that at Schlehitten, near a house of the Earl of Dohna, he saw two Swallows just come out of the waters, that could, scarcely stand, being very wet and weak, with their wings hanging on the ground; and that he observed the Swallows to be often weak for some days after their appearance."[113] The Academy of Upsal received the winter submersion of the Swallows as an undoubted fact, and even Cuvier admits as "well authenticated, that they fall into a lethargic state during winter, and even that they pass that season at the bottom of marshy waters."[114] One would think that a zoological statement which Linnæus and Cuvier accepted, must be fact; yet it remains utterly improbable. In Germany, a reward of an equal weight in silver was publicly offered to any one who should produce Swallows found under water, but we are assured that no one was found to claim the money. We may safely dismiss the notion of submersion till better authenticated; but that of torpidity is still open to examination. Statements to the effect that quantities of Swallows in a death-like condition have been found in hollow trees, holes in cliffs, banks, &c., are even more common than those of their submersion; and they seem to obtain credence in all the temperate or cold regions where the Swallows are found. It is hard to think that a persuasion so widely diffused can be wholly groundless.