every one knows; for who ever saw any
of the tribe wheeling and traversing through the sky in the frosts of
January or February? But so do the Bats and the Butterflies. Now, the
Bats hybernate with us, concealing themselves in crevices, caves, hollow
trees, unused buildings, and similar places; so do the house-flies; so
do the butterflies, some species at least, and many other insects. Do
the Swallows hybernate? That they do is a very old opinion; and those
homely but wide-spread rhymes that record so many accepted facts in
popular natural history, record _this_ as a fact. Our rustic children
sing--

"The bat, the bee, the butterfly,
The cuckoo and the swallow,
The corn-crake and the wheat-ear,
They all sleep in the hollow."

Local variations--what we may call _lectiones variae_--exist; for
example, in the south-east of our island, the third line runs,

"The corn-crake and the _nightingale_."

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
Academicae_, 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 Linnaeus 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