The Portland daily press., 1880-03-09
Information.

| Most beasts do not hibernate, because they
| have the power of keeping up uniform body
| temperature in spite Of the cold of winter. In
| the dormouse, marmot and many allied forms,
| however, as also in the hedgehog and in bats,
we do find this winter sleep to occur. The
lower animals, such as reptiles, frogs, and efts,
many fishes, spiders, shell fish and worms also
enter into this state; while yet lower creatures
| such as infusoria and rhizopods, protect them
selves by excreting and forming a structure
less, spheroidal coat of "cyst." In preparing
to hibernate, animals seek secluded and shell
tered hooks or burrows in the dry ground or in
mud or conceal themselves in moss or beneath
the bark of trees. There they fall into a sleep
(either uninterrupted or interrupted by inter-
walls of activity which endures more or less ac-
corGing to latitude and consequent length of
winter. During this sleep the body heat of
warm-blooded animals falls greatly, as respira
tion and circulation take place very gently and
slowly, the fat of the body generally consider.
able at the commencement of hibernation) be-.
ing used up in the process, unless occasional
awaking has given an opportunity for feeding
An annual period of repose, analogous to hi
bernation, also takes place during the dry sea-
son in many tropical animals-as in many rep
tiles, frogs and fishes-e. g., Lspidosiren. The
Tanree (Centetes) of Madagascar, which has a
superficial resemblance to the hedgehog, also
resembles it as to it annual torpor, and certain
lemuriods (of the genus Cheirogaleus) which
inhabit 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 al
legged, disappears by the time that the period
of activity has returned. Parallel with the Pc
riodc repose of animals is the win
ter inactivity of very many plants which ia
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 almost to a stand
still. to be renewed with rapidity and sud-
denness not inaptly termed "burst of vegeta-
ton at period which varies according to the
species. The annual torpor of animals is a
prolongatlon for weeks or for months of that
process, so familiar yet mysterious, called
sleep. During it, the functions of life are
slackened i'll their operations, and the refresh
ment which sleep produces is not due to any
accelerated nutrition, but to temporary ces-
sation of the wear and tear of activity The
Immediate cause of sleep is not vet satisfacto-
rily known. 1t is intimately connected with
some condition of the nervous centres, 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 ade-
quately supported by facts. During sleep, the
limbs are generally relaxed. and the position
assumed by the body is often that which the
embryo had taken before birth. The nervous
centres are also more or less completely cut off
from external influences the avenues of spec
ial sense being more or less obstructed by tho
position assumed by the body blythe closing
OF the eyelids, &c. Not only is this the case,
but the very stimuli received fail to excite re-
sponse unless they are of much more than or
dinary intensity. Indeed, whom exhaustion
has been very great and sleep long deferred
stimuli are powerlesS, and the access 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 process of refreshment, induced by
sleep, becomes more and more per
fected, q 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 centres to their wonted activity.
But although these centres are during sleep
more or less deprived of commerce with the
external world, they still maintain certain
activity, as is evidenced by dreams which often
elicit sounds and slight movements even in the
lower animals (e. e., i'll dogs) as well as in our
selves. 1t may, indeed, be that we always
dream when asleep, though our dreams are
generally forgotten Immediately awaken
ing. This question cannot be absolutely de-
termined, though, on the whole, it seems more
probable that it is only in imperfect sleep that
we dream. That our nervous centres are not
entirely cut off from the external world is
proved by our dreams being often influenced
by sounds, smells, or touches. Indeed, a very
active commerce with the external world must
take place in the abnormal 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 with
the greatest readiness while remaining utterly
paralyzed as regards his voluntary actions.
Plants, since they have no nervous system.
can have nothing really similar to the sleep of
animals, yet many plants assume special posi-
tions as to parts Of their frame with the ap-,
proaoh OF night. Foliage-leaves will fold them
selves, and flowers will close, movements
which as yet have received no adequate expla-
nation, as will appear when we come to con-
slider the relation of living beings to one anoth-
er.-St G. Mivart, in Contemporary Review.