Apart from any consideration of the bath as a remedial measure, in cases
of disease, its importance as an agent for preserving the health, and
granting to those who use it judiciously a reasonable hope of long life,
cannot easily be over-estimated. But in order to understand properly
the beneficial action of baths on the system, we must have some little
knowledge of the physiology of the skin. Without such knowledge, all
arguments that we could adduce in favour of the constant use of the bath
in some shape or form, would be of the _post hoc propter hoc_ kind, and
therefore of little value.
What, then, we may ask, are the uses of the skin, for what ends has
Nature designed it, and what is its _modus operandi_? Briefly stated,
the uses of the skin are as follows:--Firstly, it covers and protects
from violence the surface of the whole body, and the various tender and
sensitive parts that lie immediately beneath it; secondly, it is the
organ of touch; thirdly, it is the great regulator of the heat of the
body; fourthly, it performs the duties of a great emunctory, and by
means of its millions of sudoriferous, or sweat glands, each with its
efferent duct; it carries off and out of the body a vast quantity of
effete matter, which, if retained in the blood, would poison it, and
therefore unfit it for the healthful performance of its functions;
fifthly, the skin acts as an absorbent; and, sixthly, it is to some
extent an organ of respiration.
The use of the skin as a protective covering to the body is apparent to
every one, and we cannot help admiring its great and perfect
adaptability for the purpose. On the soles of the feet, and palms of
the hands, it is thicker than in other places, being thereon subjected
to more wear and tear; on the trunk of the body, and on the arms it is
soft and smooth, and it is everywhere wonderfully elastic and pliable.
Moreover, it is lined throughout with a base work of fat, which gives
extra support and security to the muscles, and, wherever in the body
protection from the results of pressure is needed, we find that this fat
is deposited in actual cushions, as under the heels, under the balls of
the toes, on the hips, etc.
And here we may remark that, whenever the elasticity of the skin is
impaired, as it is in the bodies of those who do not accustom themselves
to the bath and perfect ablution, loathsome diseases are apt to be the
result, which not only interfere with the actions of the skin itself,
but lower the vitality of the whole system.
The use of the skin as an organ of touch is equally apparent. Being
supplied with a most intricate network of blood vessels and nerves, the
skin is all over a most sensitive organ, and thus serves to warn us in
time of the approach of anything likely to be detrimental to our health.
If we sit in a draught, the skin of the body chills almost at once; it
begins to creep, as it were, warning us that it is time to move, time to
seek shelter, or protect ourselves by an extra garment. Some portions
of the skin are far more sensitive than others; that of the eyelids, for
instance, which is agitated by the slightest breath of air, or by a
touch communicated to it by the least pressure on the eyelashes.
By means of, or through, the medium of its vast number of sweat glands,
the skin regulates the amount of heat in our bodies. This is a function
which is much more important than most people might at first imagine.
The temperature of the body in health is about 99 degrees Fahrenheit, if
it rises much above this--even a few degrees, indeed--or if it falls
much below it, severe illness is indicated, danger is apparent, danger
even to life itself. An equable temperature of the body it is therefore
evident is alone compatible with perfect health, but if it were not for
the perspiratory system, when any extra strain is put upon the body, as
by hard work, or hard exercise, heat would accumulate in the system, and
the temperature of the body would be raised, to our discomfort,
detriment, and danger. But the pores of the skin are our safety valves;
from exertion the blood is determined to the surface, the sweat glands
are thus excited to increased action, and perspiration is thrown off in
abundance, which, passing off in steam, carries with it--in obedience to
a law too well known to need explanation--all the extra caloric. In hot
weather, a great deal of heat is thus expended through the skin; in cold
weather the kidneys are more active, and they excrete the water which
otherwise would have passed through the pores, and by storing it for a
time in a reservoir designed for the purpose, conserve the heat of the
system, and prevent lowering of the animal temperature.
By means of these same sweat glands with their ducts or pores, an
immense amount of effete matter is carried off from the body in the
course of twenty-four hours, which, as already stated, if retained in
the system, would tend to lower vitality by poisoning the blood.
If the reader recollects that the lungs also perform a renovating
function on the blood, and thus on the body, that oxygen is inhaled, and
that air loaded with carbonic acid, water, etc, exhaled, he will readily
understand how much assistance the respiratory organs receive from a
healthy acting skin.
Nor can the intelligent reader be unaware that the nutrient portion of
the food we eat, after undergoing the process of digestion performed in
the mouth--where it is masticated and mingled with the solvent saliva--
in the stomach, where it is reduced by muscular action, and the gastric
juices to the pulp called chyme--in the upper portions of the
intestines--where it receives the secretions of liver and pancreas and
becomes chyle, is collected by a series of absorbent vessels which unite
at last to form the thoracic duct, or grand chyle canal, which empties
itself of its valuable contents directly into one of the largest veins
in the body, and is thus mingled with the general circulation. He
knows, too, that the pure life-giving arterial blood, which, rushing
onwards from that mighty force-pump, the heart, is distributed to every
atom of the system, returns at last laden with the used up particles of
the tissues; that, in fact, a constant change is going on in the system,
a constant deposit of new matter, a constant discharge of old. And that
the dark venous blood, containing the effete matter, rushes through the
lungs, therein to be spread out, and chemically united to the oxygen of
the air that we breathe, before it is again pumped out towards the
tissues to supply them with heat and life. But it must not be
forgotten, that not the lungs only, but the kidneys, the liver, and the
spleen have each and all of them their duties to perform towards the
blood; and last, but not least, that the skin, when in a state of
health, assists them in no small degree in performing their several
functions.
But there are other glands which receive assistance from the skin in the
performance of their duties. We refer to those distributed here and
there in the frame-work of the body, notably in the axilla, the groin,
and under the skin of the neck, and whose functions are to purify, in
some way or other, the matter collected by a series of vessels called
the lymphatics, before it is again applied to the purposes of nutrition.
"The amount of fluid," says a well-known physiologist, "exhaled from the
skin and lungs in twenty-four hours, averages about three or four
pounds. And there is good reason to think that this excretion is of the
greatest importance in carrying off certain substances that would prove
injurious if allowed to remain in the blood.
"That which is called the Hydrophatic system, proceeds upon the plan of
increasing the cutaneous exhalation to a very large amount; and there
seems much evidence that certain deleterious matters, the presence of
which in the blood gives rise to gout, rheumatism, etc, are drawn off
from it more speedily and certainly in this way than in any other."
If space permitted, the utility of the skin as one of the greatest
emunctories of the system might be much enlarged upon; we trust,
however, we have said quite enough to establish its importance in the
animal economy.