The Caledonian. [volume] (St. Johnsbury, Vt.) 1837-1867, 1846-04-11
Art and Science.

RESPIRATION. The Portland Mirror
gives sketch ola Lecture on this subccr,
recently delivered by Rev. Mr. Chickering
before the Society ofNaural History.
The subject was considered under four tliL
visions. |. The Anatomical. 2. The Me
chanical. .. The Chemical. 4. Tic Prac-
teal.
i The Anatomical. The necessity OF
this function was tested by its universally.
So generally prevalent was it in every form
of animal life, that although it had not been.
proved actuallyto exist in some Oflhc lower
orders ofthc animal kingdom, the pure air
was rs necessary 10 the sustenancc of life,
as was meat or drink. Fishes breathed air,
10y q peculiar arrangement of organs, called
Branchjac or gills, these separated air from
the medium in which they lived, and fish ~
ing upon the banks OF river, dies ofsuffoca-
ton, JUST as much as does Il man, who lies at
the bottom. Insects have air tubes along tho
surface otthe body, communicating with the
external air, by means OF minute orticcs term
ed spiraces, which in some are guarded by
valves, in others, by tufts ofhair. The large
veins seen in the wings of some insects, are
air tubes, intended not only TO assist the in
sect in flying, but as reservoirs ofair. In man,
respiration is carried on by means ofthe lungs,
which are situated in the chest, and are walled
in by the ribs audthc breast bone. They are
two in number, differing in form and size, in
order 10 accommodate themselves to tho
space afforded them by the subjaceut organs. e
They are composed of iuuumerahe vesicles,
or little cells, the smallest ofwhich are invis-
bic TO the naked eye. The air is conducted
to them by the wind pipe, which divides and
sends off two branches, one to each lung,
termed Bronch
2. The Mechanical. Across the bottom of
the cavity, where the lungs are situated, there
is a membrane composed chiefly of muscular
fibre, which in the act of inhaling, is drawn
downward. The lungs almost completely
filling this cavity when in its natural state,
upon the membrane being drawn, a vacuum
is formed, which the external air thus rushes
in to fill, and thus initiates the lungs. The
membrane returning to its natural state, com
presses, and thus enptics the lungs of the air
inhaled. Although while man is awake, this
function is so much under the control of the
will, as TO be in considerable degree under
its government, yet by merciful provisiou,it
is also placed at the command of some the
involuntary nerves, or those nerves which gov
ern the other functions not under the control
of the will, as Circulation, Absorption, Diges-
ton, &c, and man can relapse into a state Of
slumber, or ofentire Inconsistencies, with
out the cessation for a single moment of this
ance is also sustained without fatigulng him.
3. The Chemical. The blood having cours-
ed through every part ofthe body, returns TO
the heart from whence it issued 1t went
out red, it returns black or very dark pur-
pie In its journey it has yielded up an eIe-
ment necessary to life which is found in the
air, namely oxygen, and has ta-
ken instead, an eXcrementtious substance,
carbonic acid. To get rid of this oxygen, il
must pass through the lungs, where it is ex-
posed to the action ofatmospheric air From
the right side of the heart il passes through
the pulmonary artery to the lungs, where
through the thinnest possible membrane. it is
exposed to the action ofthe mir, its color is
changed from dark purple to bright red,
and it is taken by the pulmonary vein and
carried back TO the heart, where it is distribu-
ted over the whole body.
A. The Practical All that has been said
above demonstrates the importance of an a
bundaut supply of air of the purest kind
The first thing which forces itself upon our
nttention,is the effect ofinjnrious modes of
dress in impeding the free play tho lungs,
and thus in one way, preventing the necessa-
~ supply ofair. Another thing is the impor-
lance Of having sleeping rooms and the apart