The Democratic advocate. [volume] (Westminster, Md.) 1865-1972, 1881-01-15
u .s1ys SIs
HIBEREATI0E.

ana many allied forms, however, as also
, in the hedgehog and in bats, we do 6nd
! this winter sleep to occur. The lower
} animals, such as reptiles, frogs and efts,
) many fishes, spiders, shellfsh and worms,
, also enter mt" this state. To preparing
to hibernate, animals seek secluded and
sheltered hooks, or burrow in the dry
ground or in mud, or conceal themselves
III m"sS or beneath the bark of trees.
There they fall iuto sleep, either unin-
terrupted or interrupted by intervals of
activity, which endures more or less ac-
cordIug to latitude and consequent length
!. of winter During this sleep the body
heat Of warm blooded animals falls greatly,
AZ respiration aud circulation take place
very gently and slowly. The nutrition of
the body is also affected very slowly, the
tat Of the body GENERALLY considerable at
the commencement of hibernation) being
used up in the process, unless occasional
awaking has given an opportunity for
feeding. An annual period of repose, an
alogous to Information, also takes place
during the dry season in many tropical
animals-as in many reptiles, frogs and
fishes. The taurec, of Madagascar, which
has superficial resemblance to the hedge
hog, also resembles it as to its annual tor
por, and certain lemuroids which iuhabit
the same island, seem also to prepare for
the torpor of the dry season by storing up
a quantity of fat in their tails, which it is
alleged, disappears by the time the period
of activity has returned. Parallel with
the periodic repose Of animals is the win
ter inactivity of many plants, which (in
temperate latitudes such as our OWN drop
their leaves, or if herbs, die down to shoot
forth again with the advent of spring.
During this time the sap retreats from the
surface, and the processes of life come al
most to a standstill, to be renewed with a
rapidity and suddenness not inaptly termed
"burst of vegetation" ut a period which
varies according to the species. The an
nual torpor of animals is prolongation
for weeks or for months of that process, SO
familiar, yet SO mysterious, called sleep.
During it the functions of life are slack
ened in their operations, and the refresh
ment which sleep produces is not due to
any accelerated nutrition, but to tempo
rary cessation of the wear and tear of ac-
tivity.
The immediate cause of sleep is not yet
satisfactorily known. 1t is intimately
connected with some condition of the ner-
vous centers, and it has been supposed that
its immediate cause was a diminished
quantity of blood in the brain but as yet
this view has not been adequately sup
ported by facts. During sleep the limbs
are generally relaxed, and the position as
sumed by the body is often that which the
embryo had taken before birth. The
nervous centers are also more or less COM
pletely cut off from external influences, the
avenues of special sense being more or less
obstructed by the position assumed by the
body, by the closure of the eyelids, etc.
Not only is this the case, but the very
stimuli received fail to excite response
unless they are of much more than ordi.
nary intensity. Indeed, when exhaustion
has been very great, and sleep long defer
red, the stimuli are powerless, and the ac-
cess of sleep becomes irresistible-as when
Damiens slept on the rack. Ordinarily,
the advent Of darkness is the signal for
sleep, but in nocturnal animals the period
of daily repose is inverted. As the pro-
cess of refreshment, induced by sleep, be-
comes more and more perfected, slighter
and slighter stimulus is alone needed to
awaken the sleeper, till, at last, the mere
changes of organic life suffice to arouse
the nervous centers to their wonted ac-
tivity. But although these centers are,
during sleep, more or less deprived of
commerce with the internal world, they
still maintain certain activity, as is evil
denced by dreams which often elicit sound
and slight movements even in the lower
animals as we'll as in ourselves. 1t may,
indeed, be that we always dream when
asleep, though our dreams are generally
forgotten Immediately on awakening. This
question cannot be absolutely determined,
though on the whole it seems more prob
able that it is only in imperfect sleep that
we dream. That our nervous centers are
not entirely cut off from the external
world is proved by our dreams being often
influenced by sounds, smells or touches.
Indeed, very active commerce with the
external world must take place in the ab-
normal sleep of the sleep-walker, who may
SO wonderfully adjust his movements to
varied conditions around him. A mere
local lethargy occurs in hypnOtism, when
the patient not only sees, hears and feels,
but replies to questions and exercises his
imagination in response to suggestions in
the greatest readiness, while remaining
utterly paralyzed as regards his voluntary
actions. Plants, since they have no ner
: yous system, can have nothing really sim
liar to the sleep of animals, yet many
, plants assume special positions as to the
parts of their frame with the approach o.
H night. Foliage leaves will fold them
selves, and flowers viii close, movement
which as yet receive no adequate expla
I; nation. - Contemporary ReUie.o.