untry. No one, I suppose, pretends that
migration of Swallows takes place in December or January; therefore it
is manifest that a certain number--more or fewer--remain. What becomes
of them? We certainly see them only occasionally: where are they on the
days on which they do not appear,--days extending to several consecutive
weeks? If they had not been torpid during those weeks, if the more
active functions of life had not been suspended, would they not
certainly have been starved? But the specimen shot on the 10th December,
and examined by Mr Bell, was in good condition, which is consistent with
but one alternative; either it had been well fed throughout the
preceding six weeks, or it had been hybernating. But the former
supposition implies that it had been habitually on the wing during that
period, as Swallows feed only on the wing; which could not have been the
case without its being noticed and recorded.

It is common to say that these occasional winter Swallows are the later
broods of young, which, being too infantile to migrate, are compelled to
linger in the country of their nativity, and becoming lethargic from the
advancing cold, at length die before the spring. But when this
hypothesis is looked at, it seems hardly tenable. In many of the
instances recorded, the specimens seen even late into the winter, are
represented as gaily and vigorously hawking for flies, or sweeping over
the water as in summer. This does not look like poor deserted orphans
starved with the cold, retiring to die; but birds in health, temporarily
awakened from normal slumber by an unusual temperature, and instantly
ready for a full use of their faculties. However, to settle the point by
fact, Mr Bell distinctly states that his specimen of December 10th was
"an adult bird, _not_ a young bird of the season."

If it should be asked why they do not appear in January or February, as
well as November and December, the answer is obvious. The winter's
lethargy of hybernating warm-blooded vertebrates is much more readily
interrupted in the earlier part of the season than in the middle and
latter part. And this is natural; for the more intense cold of January
benumbs and suspends the vital functions far more completely, and the
_coma_ so superinduced is sufficiently deep to resist the counteracting
influence of a few warm days, even though the temperature should be as
high as on those earlier days that awakened them, or even higher.

The aggregat