which roam abroad in quest of prey during
the night, sleep by day. It is a curious
circumstance, however, that this order of their
nature is reversed in those animals which are
kept in captivity; thus it may be observed
that the lions, tigers, hyænas, &c., in the
Zoological Gardens, remain awake during the
day, and sleep by night. They accommodate
themselves, so far, to the uses of " civilisation."
The Monkey tribes—particularly the
ringtails and smaller species, are very restless;
but the great baboon or Chimpanzee,
the organisation of whose brain very closely
resembles that of Man, will take his six or
eight hours' sleep, if undisturbed. We therefore
come to the conclusion that the more fully
developed the nervous system is the greater
being the amount of nervous energy that is
successively generated and exhausted, as it
were, from its electrical battery—the greater
will be the quantity of sleep required; hence
it has been truly remarked, that " Man sleeps
longer than any of the larger animals."

Let us now draw near to the bedside, and
consider more attentively this mysterious
state;—let us examine the phenomena of
Sleep.

It will be observed that the breathing is
slower than it is when we are awake; the
inspirations are fuller and deeper, and there is
a greater interval between them. They also
take place with an increased sound; and,
when very forcible, the most " unmusical " of
instruments, viz., the nose, is " called upon"
for a song—and snoring occurs; more
especially if the tongue touch the palate, or the
mouth remain partially open. In these cases
the inspired and expired air encounters an
obstruction; and when the soft palate at the
back of the mouth is thrown thereby into a
state of vibration, a louder and more discordant
noise is produced. Many persons, however,
particularly young people who are delicate,
breathe very gently; their respiration, during
sleep, is sometimes scarcely audible.

We have known a lady in extreme grief lie
in a kind of trance, breathing so feebly for
nearly a fortnight, that her respiration was
scarcely perceptible to the ear. It is the same
in infancy; and under the exhaustion
produced by many diseases, there would
appear to be no manifest boundary between
sleep and death. Like the respiration, the
circulation also diminishes in rapidity; the
pulse becomes slower and fuller. The vessels
of the skin relax; and it has been proved that
a person sleeping healthfully and without any
artificial means to promote it, will during an
undisturbed sleep in a given space of time,
perspire insensibly twice as much as a person
awake. The temperature of the body, under
such circumstances, falls somewhat below its
waking standard; which, in the management
or discipline of sleep, is a matter of considerable
importance. On this account, during
sleep, there is less resistance to the cooling
power and morbid effects of cold than when
we are awake. " Therefore," says Dr. Elliotson,
" persons cover their heads before going
to sleep; and when habit has not overcome
the necessity for this, cold is continually
caught from its neglect. A draught of air is
far more dangerous in the sleeping state, and
the back of the body appears less vigorous
than the front, as a draught at the back is
much more dangerous than in front." The
cause of this is obvious: the cold strikes
directly on the spinal column—the back-bone
having, unlike the chest, very little muscular
protection. It is important, therefore, that
during sleep the back should be well covered.
Dr, Elliotson adds, that " agues are caught
more readily if persons fall asleep; " which
may be explained by this simple fact, that
although the muscular system is relaxed and
prostrate, and the organs of sense veiled, as it
were, from communion with the external
world, the processes of absorption, digestion,
and nutrition go on with increased activity.
The function of absorption is particularly
active, which explains the danger of sleeping
in marshy places, or where there is a succession
of palludal exhalations. Already we
have observed, that during sleep—when the
nervous system is in repose, the temperature
of the- body is reduced—there is less animal
heat generated; hence arises the danger of
yielding to sleep when exposed to cold. " The
power of intense cold in producing sleep," as
Dr. Macnish observed, is very great in the
human subject; and nothing in the winter
season is more common than to find people
lying dead in the fields and the highways from
such a cause. When Dr. Solander was crossing
the mountains which divide Sweden from
Norway, in company with Sir Joseph Banks
and several other gentlemen, he warned them,
saying, '' Whoever sits down will sleep; and
whoever sleeps will wake no more." Shortly
afterwards Dr. Solander was the first who felt
an irresistible inclination to lie down, and one
of his fellow travellers, Mr. Bichmond,
persisted in doing the same, declaring that " he
desired nothing better than to lie down and
die." Both lay down. Finding it impossible
to proceed with them, Sir Joseph Banks and
the rest lit fires with brushwood around them;
having done which, Sir Joseph endeavoured
to wake Dr. Solander, and happily succeeded;
but though he had not slept five minutes, he
had almost lost the use of his limbs, and the
muscles were so shrunk, that the shoes fell
from his feet. He consented to go forward
with such assistance as could be given him;
but no attempts to relieve Mr. Bichmond were
successful—he died on the spot. In severe
winter weather, when the poor suffer much
from cold, blankets are almost as indis-
pensable to them as food. There is also one
very interesting and important fact connected
with this subject; it is that sleep promotes
the cure of all diseases. What the physicians
of old called " the crisis " occurs in this state,
and it is not, therefore without reason that