Hygienic Physiology
by
Joel Dorman Steele
Part 4 out of 7
46. Will liquor help one to endure cold and exposure?
47. What is a fatty degeneration of the kidneys?
48. Contrast the action of alcohol and water in the body.
49. Is alcohol, in any proper sense of the term, a food?
50. Does liquor strengthen the muscles of a working man?
51. Is liquor a wholesome "tonic"?
52. Is it a good plan to take a glass of liquor before dinner?
VII.
THE NERVOUS SYSTEM.
"Mark then the cloven sphere that holds
All thoughts in its mysterious folds,
That feels sensation's faintest thrill,
And flashes forth the sovereign will;
Think on the stormy world that dwells
Lock'd in its dim and clustering cells;
The lightning gleams of power it sheds
Along its hollow, glassy threads!"
"As a king sits high above his subjects upon his throne, and from it
speaks behests that all obey, so from the throne of the brain cells is all
the kingdom of a man directed, controlled, and influenced. For this
occupant, the eyes watch, the ears hear, the tongue tastes, the nostrils
smell, the skin feels. For it, language is exhausted of its treasures, and
life of its experience; locomotion is accomplished, and quiet insured.
When it wills, body and spirit are goaded like overdriven horses. When it
allows, rest and sleep may come for recuperation. In short, the slightest
penetration may not fail to perceive that all other parts obey this part,
and are but ministers to its necessities."--Odd Hours of a Physician.
ANALYSIS OF THE NERVOUS SYSTEM.
_
| 1. THE STRUCTURE
| _
| _ | 1. _Description._
| | 1. The Brain........| 2. _The Cerebrum._
| | |_3. _The Cerebellum._
| | _
| | 2. The Spinal Cord..| 1. _Its Composition._
| | |_2. _Medulla Oblongata._
| | _
| 2. ORGANS OF | | 1. _Description._
| THE NERV- | | 2. _Motory and Sensory._
| OUS SYSTEM..| | 3. _Transfer of Pain._
| | | 4. _The Spinal Nerves--
| | | 31 Pairs._
| |_3. The Nerves.......| 5. _The Cranial Nerves--
| | 12 Pairs._
| | 6. _Sympathetic System._
| | 7. _Crossing of Cords._
| | 8. _Reflex Action._
| | 9. _Uses of Reflex
| |_ Action_
| _
| | 1. Brain Exercise.
| | 2. Connection between Brain Growth and Body Growth.
| 3. HYGIENE.....| 3. Sleep.
| | 4. Effect of Sleeping Draughts.
| |_5. Sunlight.
|
| 4. WONDERS OF THE BRAIN.
| _
| | 1. Alcohol (Con'd.)
| | _ | 1. _Stage of Excitement._
| || | 2. _Stage of Muscular
| || | Weakness._
| || 1. Effect of Alco- | 3. _Stage of Mental
| || hol upon the | Weakness._
| || Nervous System | 4. _Stage of Unconscious-
| || |_ ness._
| ||
| || 2. Effect upon the Brain
| ||_3. Effect upon the Mental and Moral Powers.
| |
| | 2. Tobacco.
| | _
| || 1. Constituents of Tobacco.
| 5. ALCOHOLIC || 2. Physiological Effects.
| DRINKS AND|| 3. Possible Disturbances produced by Smoking.
|_ NARCOTICS.|| 4. Influence upon the Nervous System.
|| 5. Is Tobacco a Food?
||_6. Influence of Tobacco on Youth.
| _
| | 1. _Description._
| 3. Opium............| 2. _Physiological
| |_ Effects._
| 4. Chloral Hydrate.
| 5. Chloroform.
|_6. Cocaine.
THE NERVOUS SYSTEM. [Footnote: The organs of circulation, respiration, and
digestion, of which we have already spoken, are often called the
vegetative functions, because they belong also to the vegetable kingdom.
Plants have a circulation of sap through their cells corresponding to that
of the blood through the capillaries. They breathe the air through their
leaves, which act the part of lungs, and they take in food which they
change into their own structure by a process which answers to that of
digestion. The plant, however, is a mere collection of parts incapable of
any combined action. On the other hand, the animal has a nervous system
which binds all the organs together.]
STRUCTURE.--The nervous system includes the _brain_, the _spinal
cord_, and the _nerves_. It is composed of two kinds of matter--
the _white_, and the _gray_. The former consists of minute,
milk-white, glistening fibers, sometimes as small as 1/25000 of an inch in
diameter; the latter is made up of small, ashen-colored cells, forming a
pulp-like substance of the consistency of blancmange. [Footnote: In
addition to the cells, the gray substance contains also nerve fibers
continuous with the white fibers, but generally much smaller. These form
half the bulk of the gray substance of the spinal cord, and a large part
of the deeper layer of the gray matter in the brain.--LEIDY'S
_Anatomy_, p. 507.] This is often gathered in little masses, termed
ganglions (_ganglion_, a knot), because, when a nerve passes through
a group of the cells, they give it the appearance of a knot. The nerve
fibers are conductors, while the gray cells are generators, of nervous
force. [Footnote: What this force is we do not know. In some respects it
is like electricity, but, in others, it differs materially. Its velocity
is about thirty three meters per second.--_Popular Physics_, p. 244,
Note.] The ganglia, or nervous centers, answer to the stations along a
telegraphic line, where messages are received and transmitted, and the
fibers correspond to the wires that communicate between different parts.
FIG. 50.
[Illustration: _The Nervous System._ A, _cerebrum_; B,
_cerebellum._]
The BRAIN is the seat of the mind. [Footnote: In proportion to the rest
of the nervous matter in the body, it is larger in man than in any of the
lower animals. It is the function which the brain performs that
distinguishes man from all other animals, and it is by the action of his
brain that he becomes a conscious, intelligent, and responsible being. The
brain is the seat of that knowledge which we express when we say _I_.
I know it, I feel it, I saw it, are expressions of our individual
consciousness, the seat of which is the brain. It is when the brain is at
rest in sleep that there is least consciousness. The brain may be put
under the influence of poisons, such as alcohol and chloroform, and then
the body is without consciousness. From these and other facts the brain is
regarded as the seat of _consciousness_.--LANKESTER.] Its average
weight is about fifty ounces. [Footnote: Cuvier's brain weighed 64 1/2
ounces; Webster's, 53 1/2 ounces; James Fisk's, 58 ounces; Ruloff's, 59
ounces; an idiot's, 19 ounces. See Table in FLINT'S _Nervous
System_.] It is egg-shaped, and, soft and yielding, fills closely the
cavity of the skull. It reposes securely on a water bed, being surrounded
by a double membrane _(arachnoid)_, delicate as a spider's web, which
forms a closed sac filled, like the spaces in the brain itself, with a
liquid resembling water. Within this, and closely investing the brain, is
a fine tissue (_pia mater_), with a mesh of blood vessels which dips
down into the hollows, and bathes them so copiously that it uses one fifth
of the entire circulation of the body. Around the whole is wrapped a tough
membrane (_dura mater_), which lines the bony box of the skull, and
separates the various parts of the organ by strong partitions. The brain
consists of two parts--the _cerebrum_, and the _cerebellum_.
The CEREBRUM fills the front and upper part of the skull, and comprises
about seven eighths of the entire weight of the brain. As animals rise in
the scale of life, this higher part makes its appearance. It is a mass of
white fibers, with cells of gray matter sprinkled on the outside, or
lodged here and there in ganglia. It is so curiously wrinkled and folded
as strikingly to resemble the meat of an English walnut. This structure
gives a large surface for the gray matter,--sometimes as much as six
hundred and seventy square inches. The convolutions are not noticeable in
an infant, but increase with the growth of the mind, their depth and
intricacy being characteristic of high mental power.
FIG. 51.
[Illustration: _Surface of the Cerebrum._]
The cerebrum is divided into two hemispheres, connected beneath by fibers
of white matter. Thus we have two brains, [Footnote: This doubleness has
given rise to some curious speculations. In the case of the hand, eye,
etc, we know that the sensation is made more sure. Thus we can see with
one eye, but not so well as with both. It is perhaps the same with the
brain. We may sometimes carry on a train of thought, "build an air castle"
with one half of our brain, while the other half looks on and watches the
operation; or, we may read and at the same time think of something else.
So in delirium, a patient often imagines himself two persons, thus showing
a want of harmony between the two halves.--DRAPER, _Human
Physiology_, p. 320.] as well as two hands and two eyes. This provides
us with a surplus of brains, as it were, which can be drawn upon in an
emergency. A large part of one hemisphere has been destroyed without
particularly injuring the mental powers, [Footnote: A pointed iron bar,
three and a half feet long and one inch and a quarter in diameter, was
driven by the premature blasting of a rock completely through the side of
the head of a man who was present. It entered below the temple, and made
its exit at the top of the forehead, just about the middle line. The man
was at first stunned, and lay in a delirious, semistupefied state for
about three weeks. At the end of sixteen months, however, he was in
perfect health, with wounds healed and mental and bodily functions
unimpaired, except that sight was lost in the eye of the injured side.--
DALTON. It is noticeable, however, that the man became changed in
disposition, fickle, impatient of restraint, and profane, which he was not
before. He died epileptic, nearly thirteen years after the injury. The
tamping iron and the skull are preserved in the Warren Anatomical Museum,
Boston.]--just as a person has been blind in one eye for a long time
without having discovered his loss. The cerebrum is the center of
intelligence and thought. [Footnote: In man, the cerebrum presents an
immense preponderance in weight over other portions of the brain; in some
of the lower animals, the cerebrum is even less in weight than the
cerebellum. Another interesting point is the development of cerebral
convolutions in certain animals, by which the relative amount of gray
matter is increased. In fishes, reptiles, and birds, the surface of the
hemispheres is smooth; but, in many mammalia, especially in those
remarkable for intelligence, the cerebrum presents a greater or less
number of convolutions, as it does in the human subject.--FLINT. The
average weight of the human brain in proportion to the entire body is
about 1 to 36. The average of mammalia is 1 to 186; of birds, 1 to 212; of
reptiles, 1 to 1,321; and of fishes, 1 to 5,668. There are some animals in
which the weight of the brain bears a higher proportion to the body than
it does in man; thus in the blue-headed tit, the proportion is as 1 to 12;
in the goldfinch, as 1 to 24; and in the field mouse, as 1 to 31. "It does
not hence follow, however, that the _cerebrum_ is larger in
proportion; in fact, it is probably not nearly so large; for in birds and
rodent animals the sensory ganglia form a very considerable portion of the
entire brain. M. Baillarger has shown that the _surface_ and the
_bulk_ of the cerebral hemispheres are so far from bearing any
constant proportion to each other in different animals that,
notwithstanding the depth of the convolutions in the human cerebrum, its
bulk is two and a half times as great in proportion to its surface as it
is in the rabbit, the surface of whose cerebrum is smooth. The _size_
of the cerebrum, considered alone, is not, however, a fair test of its
intellectual power. This depends upon the quantity of _vesicular
matter_ which it contains, as evinced not only by superficial area, but
by the number and depth of the convolutions and by the thickness of the
cortical layer."--CARPENTER.] Persons in whom it is seriously injured or
diseased often become unable to converse intelligently, both from
inability to remember words and from loss of power to articulate them.
THE CEREBELLUM lies below the cerebrum, and in the back part of the head
(Fig. 50). It is about the size of a small fist. Its structure is similar
to that of the brain proper, but instead of convolutions it has parallel
ridges, which, letting the gray matter down deeply into the white matter
within, give it a peculiar appearance, called the _arbor vitę_, or
tree of life (Fig. 55). This part of the brain is the center for the
control of the voluntary muscles, [Footnote: The exact nature of the
functions of the cerebellum is one of those problems concerning which
there is no unanimity of opinion amongst physiologists. It may be
premised, however, that the knowledge we at present possess does enable us
to come to one very important conclusion with respect to the functions of
the cerebellum,--it enables us to say that this organ has no independent
function either in the province of mind or in the province of motility.
And we may perhaps safely affirm still further, that the cerebellum is
much more intimately concerned with the production of bodily movements
than with the evolution of mental phenomena. The anatomical distinctness
of the cerebellum from the larger brain and other parts of the nervous
system is more apparent than real....That there is an habitual community
of action between the cerebellum and the spinal cord is, I believe,
doubted by none, and the fact that an intimate functional relationship
exists between the cerebrum and the cerebellum is shown by the
circumstance that atrophy of one cerebral hemisphere entails a
corresponding atrophy of the opposite half of the cerebellum. The
subordinate or supplementary nature of the cerebellar function, however,
in this latter relation seems equally well shown by the fact that atrophy
of one side of the cerebellum (when it occurs as the primary event) does
not entail any appreciable wasting in the opposite half of the cerebrum.
What other conclusion can be drawn? If the cutting off of certain cerebral
stimuli leads to a wasting of the opposite half of the cerebellum, this
would seem to show that each half of the cerebellum is naturally called
into activity in response to, or conjointly with, the opposite cerebral
hemisphere. Whilst conversely, if atrophy of one half of the cerebellum
does not entail a relative diminution in the opposite cerebral hemisphere,
this would go to show that the cerebral hemispheres do not act in response
to cerebellar stimuli, since their nutrition does not suffer when such
stimuli are certainly absent. The action of the cerebrum is therefore
shown to be primary, whilst that of the cerebellum is secondary or
subordinate in the performance of those functions in which they are both
concerned.--H. CHARLTON BASTIAN, _Paralysis from Brain Disease_.]
particularly those of locomotion. Persons in whom it is injured or
diseased walk with tottering and uncertain movements as if intoxicated,
and can not perform any orderly work.
THE SPINAL CORD occupies the cavity of the backbone. It is protected by
the same membranes as the brain, but, unlike it, the white matter is on
the outside, and the gray matter is within. Deep fissures separate it into
halves (Fig. 50), which are, however, joined by a bridge of the same
substance. Just as it starts from the brain, there is an expansion called
the _medulla oblongata_ (Fig. 55).
THE NERVES are glistening, silvery threads, composed, like the spinal
cord, of white matter without and gray within. They ramify to all parts of
the body. Often they are very near each other, yet are perfectly distinct,
each conveying its own impression. [Footnote: Press two fingers together,
and, closing the eyes, let some one pass the point of a pin lightly from
one to the other; you will be able to tell which is touched, yet if the
nerves came in contact with each other anywhere in their long route to the
brain, you could not thus distinguish.] Those which carry the orders of
the mind to the different organs are called the _motory_ nerves;
while those which bring back impressions which they receive are styled
_sensory_ nerves. If the sensory nerve leading to any part be cut,
all sensation in that spot will be lost, while motion will remain; if the
motory nerve be cut, all motion will be destroyed, while sensation will
exist as before.
TRANSFER OF PAIN.--Strictly speaking, pain is not in any organ, but in the
mind, since only that can feel. When any nerve brings news to the brain of
an injury, the mind refers the pain to the end of the nerve. A familiar
illustration is seen in the "funny bone" behind the elbow. Here the nerve
(_ulnar_) gives sensation to the third and fourth fingers, in which,
if this bone be struck, the pain will seem to be. Long after a limb has
been amputated, pain will be felt in it, as if it still formed a part of
the body--any injury in the stump being referred to the point to which the
nerve formerly led. [Footnote: Only about five per cent. of those who
suffer amputation lose the feeling of the part taken away. There is
something tragical, almost ghastly, in the idea of a spirit limb haunting
a man through his life, and betraying him in unguarded moments into some
effort, the failure of which suddenly reminds him of his loss. A gallant
fellow, who had left an arm at Shiloh, once, when riding, attempted to use
his lost hand to grasp the reins while with the other he struck his horse.
A terrible fall was the result of his mistake. When the current of a
battery is applied to the nerves of an arm stump, the irritation is
carried to the brain, and referred to all the regions of the lost limb. On
one occasion a man's shoulder was thus electrized three inches above the
point where the limb was cut off. For two years he had ceased to be
conscious of his limb. As the electric current passed through, the man,
who had been profoundly ignorant of its possible effects, started up,
crying, "Oh, the hand! the hand!" and tried to seize it with the living
grasp of the sound fingers. No resurrection of the dead could have been
more startling.--DR. MITCHELL _on "Phantom Limbs" in Lippincott's
Magazine_.]
The nerves are divided into three general classes--the _spinal_, the
_cranial_, and the _sympathetic_.
FIG. 54.
[Illustration: P, _posterior root of a spinal nerve;_ G,
_ganglion;_ A, _anterior root;_ S, _spinal nerve. The white
portions of the figure represent the white fibers; and the dark, the
gray._]
THE SPINAL NERVES, of which there are thirty-one pairs, issue from the
spinal cord through apertures provided for them in the backbone. Each
nerve arises by two roots; the anterior is the motory, and the posterior
the sensory one. The posterior alone connects directly with the gray
matter of the cord, and has a small ganglion of gray matter of its own at
a little distance from its origin. These roots soon unite, _i. e_.,
are bound up in one sheath, though they preserve their special functions.
When the posterior root of a nerve is cut, the animal loses the power of
feeling, and when the anterior root is cut, that of motion.
THE CRANIAL NERVES, twelve pairs in number, spring from the lower part of
the brain and the medulla oblongata.
1. The _olfactory_, or first pair of nerves, ramify through the
nostrils, and are the nerves of smell.
2. The _optic_, or second pair of nerves, pass to the eyeballs, and
are the nerves of vision.
3, 4, 6. The _motores oculi_ (eye movers) are three pairs of nerves
used to move the eyes.
5. The _trifacial_, or fifth pair of nerves, divide each into three
branches--hence the name--the first to the upper part of the face, eyes,
and nose; the second to the upper jaw and teeth; the third to the lower
jaw and the mouth, where it forms the nerve of taste. These nerves are
implicated when we have the toothache or neuralgia.
7. The _facial_, or seventh pair of nerves, are distributed over the
face, and give it expression. [Footnote: If it is palsied, on one side
there will be a blank, while the other side will laugh or cry, and the
whole face will look funny indeed. There were some cruel people in the
middle ages who used to cut the nerve and deform children's faces in this
way, for the purpose of making money of them at shows. When this nerve was
wrongly supposed to be the seat of neuralgia, or tic douloureux, it was
often cut by surgeons. The patient suffered many dangers, and no relief of
pain was gained.--MAPOTHER.]
FIG. 55.
[Illustration: _The Brain and the origin of the twelve pairs of Cranial
Nerves._ F, E, _the cerebrum;_ D, _the cerebellum, showing the
arbor vitę;_ G, _the eye;_ H, _the medulla oblongata;_ A,
_the spinal cord;_ C and B, _the first two pairs of spinal
nerves._]
8. The _auditory_, or eighth pair of nerves, go to the ears, and are
the nerves of hearing.
9. The _glos-so-pha-ryn'-ge-al_, or ninth pair of nerves, are
distributed over the mucous membrane of the pharynx, tonsils, etc.
10. The _pneu-mo-gas'-tric_, or tenth pair of nerves, preside over
the larynx, lungs, liver, stomach, and one branch extends to the heart.
This is the only nerve which goes so far from the head.
11. The _accessory_, or eleventh pair of nerves, rise from the spinal
cord, run up to the medulla oblongata, and thence leave the skull at the
same opening with the ninth and tenth pairs. They regulate the vocal
movements of the larynx.
12. The _hyp-o-glos'-sal_, or twelfth pair of nerves, give motion to
the tongue.
FIG. 56.
[Illustration: _Spinal Nerve, Sympathetic Cord, and the Network of
Sympathetic Nerves around the Internal Organs_. K, _aorta;_ A,
_ophagus;_ B, _diaphragm;_ C, _stomach._]
THE SYMPATHETIC SYSTEM contains the nerves of organic life. It consists of
a double chain of ganglia on either side of the backbone, extending into
the chest and abdomen. From, these, delicate nerves, generally soft and of
a grayish color, run to the organs on which life depends--the heart,
lungs, stomach, etc.--to the blood vessels, and to the spinal and cranial
nerves over the body. Thus the entire system is bound together with cords
of sympathy, so that, "if one member suffers, all the members suffer with
it."
Here lies the secret of the control exercised by the brain over all the
vital operations. Every organ responds to its changing moods, especially
those of respiration, circulation, digestion, and secretion,--processes
intimately linked with this system, and controlled by it. (See p. 330.)
CROSSING OF CORDS.--Each half of the body is presided over, not by its own
half of the brain, but that of the opposite side. The motory nerves, as
they descend from the brain, in the medulla oblongata, cross each other to
the opposite side of the spinal cord. So the motor nerves of the right
side of the body are connected with the left side of the brain, and
_vice versa_. Thus a derangement in one half of the brain may
paralyze the opposite half of the body. The nerves going to the face do
not thus cross, and therefore the face may be motionless on one side, and
the limbs on the other. Each of the sensory fibers of the spinal nerves
crosses over to the opposite side of the spinal cord, and so ascends to
the brain; an injury to the spinal cord may, therefore, cause a loss of
motion in one leg and of feeling in the other.
REFLEX ACTION.--Since the gray matter generates the nervous force, a
ganglion is capable of receiving an impression, and of sending back or
_reflecting_ it so as to excite the muscles to action. This is done
without the consciousness of the mind. [Footnote: Instances of an
unconscious working of the mind are abundant. An illustration, often
quoted, is given, as follows, by Dr. Abercrombie, in his _Intellectual
Powers_:
"A lawyer had been excessively perplexed about a very complicated
question. An opinion was required from him, but the question was one of
such difficulty that he felt very uncertain how he should render it. The
decision had to be given at a certain time, and he awoke in the morning of
that day with a feeling of great distress. He said to his wife, 'I had a
dream, and the whole thing was clearly arranged before my mind, and I
would give anything to recover the train of thought.' His wife said to
him, 'Go and look on your table.' She had seen him get up in the night and
go to his table and sit down and write. He did so, and found there the
opinion which he had been most earnestly endeavoring to recover, lying in
his own handwriting. There was no doubt about it whatever."
In this case the action of the brain was clearly automatic, _i. e._,
reflex. The lawyer had worried his brain by his anxiety, and thus
prevented his mind from doing its best. But it had received an impulse in
a certain direction, and when left to itself, worked out the result. (See
Appendix for other illustrations.)] Thus we wink involuntarily at a flash
of light or a threatened blow. [Footnote: A very eminent chemist a few
years ago was making an experiment upon some extremely explosive compound
which he had discovered. He had a small quantity of this compound in a
bottle, and was holding it up to the light, looking at it intently; and
whether it was a shake of the bottle or the warmth of his hand, I do not
know, but it exploded in his hand, and the bottle was shivered into a
million of minute fragments, which were driven in every direction. His
first impression was that they had penetrated his eyes, but to his intense
relief he found presently that they had only struck the outside of his
eyelids. You may conceive how infinitesimally short the interval was
between the explosion of the bottle and the particles reaching his eyes;
and yet in that interval the impression had been made upon his sight, the
mandate of the reflex action, so to speak, had gone forth, the muscles of
his eyelids had been called into action, and he had closed his eyelids
before the particles had reached them, and in this manner his eyes were
saved. You see what a wonderful proof this is of the way in which the
automatic action of our nervous apparatus enters into the sustenance of
our lives, and the protection of our most important organs from injury.--
DR. CARPENTER.] We start at a sudden sound. We jump back from a precipice
before the mind has time to reason upon the danger. The spinal cord
conducts certain impressions to the brain, but responds to others without
troubling that organ. [Footnote: There is a story told of a man, who,
having injured his spinal cord, had lost feeling and motion in his lower
extremities. Dr. John Hunter experimented upon him. Tickling his feet, he
asked him if he felt it; the man, pointing to his limbs, which were
kicking vigorously about, answered, "No, but you see my legs do."
Illustrations of this independent action of the spinal cord are common in
animals. A headless wasp will ply its sting energetically. A fowl, after
its head is cut off, will flap its wings and jump about as if in pain,
although, of course, all sensation has ceased. "A water beetle, having had
its head removed, remained motionless as long as it rested on a dry
surface, but when cast into water, it executed the usual swimming motions
with great energy and rapidity, striking all its comrades to one side by
its violence, and persisting in these for more than half an hour."] The
medulla oblongata carries on the process of respiration. The great
sympathetic system binds together all the organs of the body.
USES OF REFLEX ACTION.--We breathe eighteen times every minute; we stand
erect without a consciousness of effort; [Footnote: In this way we account
for the perilous feats performed by the somnambulist. He is not conscious,
as his operations are not directed by the cerebrum, but by the other
nervous centers. Were he to attempt their repetition when awake, the
emotion of fear might render it impossible.] we walk, eat, digest, and at
the same time carry on a train of thought. Our brain is thus emancipated
from the petty detail of life. If we were obliged to attend to every
breath, every pulsation of the heart, every wink of the eye, our time
would be wasted in keeping alive. Mere standing would require our entire
attention. Besides, an act which at first demands all our thought soon
requires less, and at last becomes mechanical, [Footnote: "As every one
knows," says Huxley, "it takes a soldier a long time to learn his drill--
for instance, to put himself into the attitude of 'attention' at the
instant the word of command is heard. But, after a time, the sound of the
word gives rise to the act, whether the soldier be thinking of it or not.
There is a story, which is credible enough, though it may not be true, of
a practical joker, who, seeing a discharged veteran carrying home his
dinner, suddenly called out 'Attention!' whereupon the man instantly
brought his hands down and lost his mutton and potatoes in the gutter. The
drill had been thorough, and its effects had become embodied in the man's
nervous structure."] as we say, _i. e._, reflex. Thus we play a
familiar tune upon an instrument and carry on a conversation at the same
time. All the possibilities of an education and the power of forming
habits are based upon this principle. No act we perform ends with itself.
It leaves behind it in the nervous centers a tendency to do the same thing
again. Our physical being thus conspires to fix upon us the habits of a
good or an evil life. Our very thoughts are written in our muscles, so
that the expression of our face and even our features grow into harmony
with the life we live.
BRAIN EXERCISE.--The nervous system demands its life and activity. The
mind grows by what it feeds on. One who reads mainly light literature, who
lolls on the sofa or worries through the platitudes of an idle or
fashionable life, decays mentally; his system loses tone, and physical
weakness follows mental poverty. On the other hand, an excessive use of
the mind withdraws force from the body, whose weakness, reacting on the
brain, produces gradual decay and serious diseases. (See p. 331.)
The brain grows by the growth of the body. The body grows through good
food, fresh air, and work and rest in suitable proportion. For the full
development and perfect use of a strong mind, a strong body is essential.
Hence, in seeking to expand and store the intellect, we should be equally
thoughtful of the growth and health of the body.
SLEEP [Footnote: Sleep procured by medicine is rarely as beneficial as
that secured naturally. The disturbance to the nervous system is often
sufficient to counterbalance all the good results. The habit of seeking
sleep in this way, without the advice of a physician, is to be most
earnestly deprecated. The dose must be constantly increased to produce the
effect, and thus great injury may be caused. Often, too, where laudanum or
morphine is used, the person unconsciously comes into a terrible and fatal
bondage. (See p. 342.) Especially should infants never be dosed with
cordials, as is a common family practice. The damage done to helpless
childhood by the ignorant and reckless use of soothing syrups is frightful
to contemplate. All the ordinary sleeping draughts have life-destroying
properties, as is proved by the fatal effects of an overdose. At the best,
they paralyze the nerve centers, disorder the digestion, and poison the
blood. Their promiscuous use is therefore full of danger.] is as essential
as food. During the day, the process of tearing down goes on; during the
night, the work of building up should make good the loss. In youth more
sleep is needed than in old age, when nature makes few permanent repairs,
and is content with temporary expedients. The number of hours required for
sleep must be decided by each person. Napoleon took only five hours, but
most people need from six to eight hours,--brain workers even more. In
general, one should sleep until he naturally wakes. If one's rest be
broken, it should be made up as soon as possible. (See p. 334.)
SUNLIGHT.--The influence of the sun's rays upon the nervous system is very
marked. [Footnote: The necessity of light for young children is not half
appreciated. Many of their diseases, and nearly all the cadaverous looks
of those brought up in great cities, are ascribable to the deficiency of
light and air. When we see the glass room of the photographers in every
street, in the topmost story, we grudge them their application to what is
often a mere personal vanity. Why should not a nursery be constructed in
the same manner? If parents knew the value of light to the skin,
especially to children of a scrofulous tendency, we should have plenty of
these glass house nurseries, where children might run about in a proper
temperature, free from much of that clothing which at present seals up the
skin--that great supplementary lung--against sunlight and oxygen. They
would save many a weakly child who now perishes from lack of these
necessaries of infant life.--DR. WINTER.] It is said also to have the
effect of developing red disks in the blood. All vigor and activity come
from the sun. Vegetables grown in subdued light have a bleached and faded
look. An infant kept in absolute darkness would grow into a shapeless
idiot. That room is the healthiest to which the sun has the freest access.
Epidemics frequently attack the inhabitants of the shady side of a street,
and exempt those on the sunny side. If, on a slight indisposition, we
should go out into the open air and bright sunlight, instead of shutting
ourselves up in a close, dark chamber, we might often avoid a serious
illness. The sun bath is doubtless a most efficient remedy for many
diseases. Our window blinds and curtains should be thrown back and open,
and we should let the blessed air and sun stream in to invigorate and
cheer. No house buried in shade, and no room with darkened windows, is fit
for human habitation. In damp and darkness, lies in wait almost every
disease to which flesh is heir. The sun is their only successful foe. (See
p. 336.)
WONDERS OF THE BRAIN.--After having seen the beautiful contrivances and
the exquisite delicacy of the lower organs, it is natural to suppose that
when we come to the brain we should find the most elaborate machinery. How
surprising, then, it is to have revealed to us only cells and fibers! The
brain is the least solid and most unsubstantial looking organ in the body.
Eighty per cent of water, seven of albumen, some fat, and a few minor
substances constitute the instrument which rules the world. Strangest of
all, the brain, which is the seat of sensation, is itself without
sensation. Every nerve, every part of the spinal cord, is keenly alive to
the slightest touch, yet "the brain may be cut, burned, or electrified
without producing pain."
ALCOHOLIC DRINKS AND NARCOTICS.
ALCOHOL (Continued from p. 187).
EFFECT UPON THE NERVOUS SYSTEM.--In the progressive influence of alcohol
upon the nervous system, there are, according to the researches of Dr.
Richardson, four successive stages.
1. THE STAGE OF EXCITEMENT. [Footnote: The pupil should be careful to note
here that alcohol does not act upon the heart directly, and cause it to
contract with more force. The idea that alcohol gives energy and activity
to the muscles is entirely false. It really, as we have seen (p. 183),
weakens muscular contraction. The enfeeblement begins in the first stage,
and continues in the other stages with increased effect. The heart beats
quickly merely because the resistance of the minute controlling vessels is
taken off, and it works without being under proper regulation. _What is
called a stimulation or excitement is, in absolute fact, a relaxation, a
partial paralysis_ of one of the most important mechanisms in the
animal body. Alcohol should be ranked among the narcotics.--RICHARDSON.]--
The first effect of alcohol, as we have already described on page 144, is
to paralyze the nerves that lead to the extreme and minute blood vessels,
and so regulate the passage of the blood through the capillary system. The
vital force, thus drawn into the nervous centers, drives the machinery of
life with tremendous energy. The heart jumps like the mainspring of a
watch when the resistance of the wheels is removed. The blood surges
through the body with increased force. Every capillary tube in the system
is swollen and flushed, like the reddened nose and cheek.
In all this there is exhilaration, but no nourishment; there is animation,
but no permanent power conferred on brain or muscle. Alcohol may cheer for
the moment. It may set the sluggish blood in motion, start the flow of
thought, and excite a temporary gayety. "It may enable a wearied or feeble
organism to do brisk work for a short time. It may make the brain briefly
brilliant. It may excite muscle to quick action, but it does nothing at
its own cost, fills up nothing it has destroyed, and itself leads to
destruction." Even the mental activity it has excited is an unsafe state
of mind, for that just poise of the faculties so essential to good
judgment is disturbed by the presence of the intruder. Johnson well
remarked, "Wine improves conversation by taking the edge off the
understanding."
2. THE STAGE OF MUSCULAR WEAKNESS.--If the action of the alcohol be still
continued, the spinal cord is next affected by this powerful narcotic. The
control of some of the muscles is lost. Those of the lower lip usually
fail first, then those of the lower limbs, and the staggering, uncertain
steps betray the result. The muscles themselves, also, become feebler as
the power of contraction diminishes. The temperature, which, for a time,
was slightly increased, soon begins to fall as the heat is radiated; the
body is cooled, and the well-known "alcoholic chill" is felt.
3. THE STAGE OF MENTAL WEAKNESS.--The cerebrum is now implicated. The
ideal and emotional faculties are quickened, while the will is weakened.
The center of thought being overpowered, the mind is a chaos. Ideas flock
in thick and fast. The tongue is loosened. The judgment loses its hold on
the acts. The reason giving way, the animal instincts generally assume the
mastery of the man. The hidden nature comes to the surface. All the gloss
of education and social restraint falls off, and the lower nature stands
revealed. The coward shows himself more craven, the braggart more
boastful, the bold more daring, and the cruel more brutal. The inebriate
is liable to become the perpetrator of any outrage that the slightest
provocation may suggest.
4. THE STAGE OF UNCONSCIOUSNESS.--At last, prostration ensues, and the
wild, mad revel of the drunkard ends with utter senselessness. In common
speech, the man is "dead drunk." Brain and spinal cord are both benumbed.
Fortunately, the two nervous centers which supply the heart and the
diaphragm are the slowest to be influenced. So, even in this final stage,
the breathing and the circulation still go on, though the other organs
have stopped. Were it not for this, every person thoroughly intoxicated
would die. [Footnote: Cold has a wonderful influence in hastening this
stage, so that a person, previously only in the first stage of excitement,
on going outdoors on a winter night, may rapidly sink into a lethargy
(become _comatose_), fall, and die. He is then commonly said to have
perished with cold. The signs of this coma are of great practical
importance, since so many persons die in police stations and elsewhere who
are really comatose, when they are supposed to be only sound asleep. The
pulse is slow, and almost imperceptible. The face is pale, and the skin
cold. "If the arm be pinched, it is not moved; if the eyeballs are
touched, the lids will not sink." The respiration becomes slower and
slower, and, if the person dies, it is because liquid collects in the
bronchial tubes, and stops the passage of the air. The man then actually
drowns in his own secretions.]
EFFECT UPON THE BRAIN.--Alcohol seems to have a special affinity for the
brain. This organ absorbs more than any other, and its delicate structure
is correspondingly affected. The "Vascular enlargement" here reaches its
height. The tiny vessels become clogged with blood that is unfitted to
nourish, because loaded with carbonic acid, and deprived of the usual
quantity of the life-giving oxygen.--HINTON. The brain is, in the language
of the physiologist, malfunctioned. The mind but slowly rallies from the
stupor of the fourth stage, and a sense of dullness and depression remains
to show with what difficulty the fatigued organ recovers its normal
condition. So marked is the effect of the narcotic poison, that some
authorities hold that "a once thoroughly intoxicated brain never fully
becomes what it was before."
In time, the free use of liquor hardens and thickens the membrane
enveloping the nervous matter; the nerve corpuscles undergo a "Fatty
degeneration"; the blood vessels lose their elasticity; and the vital
fluid, flowing less freely through the obstructed channels, fails to
afford the old-time nourishment. The consequent deterioration of the
nervous substance--the organ of thought--shows itself in the weakened mind
[Footnote: The habitual use of fermented liquors, even to an extent far
short of what is necessary to produce intoxication, injures the body, and
diminishes the mental power.--Sir Henry Thompson.] that we so often notice
in a person accustomed to drink, and at last lays the foundation of
various nervous disorders--epilepsy, paralysis, and insanity. [Footnote:
Casper, the great statistician of Berlin, says: "So far as that city is
concerned, one third of the insane coming from the poorer classes, were
made so by spirit drinking."] The law of heredity here again asserts
itself, and the inebriate's children often inherit the disease which he
has escaped.
Chief among the consequences of this perverted and imperfect nutrition of
the brain is that intermediate state between intoxication and insanity,
well known as Delirium Tremens. "It is characterized by a low, restless
activity of the cerebrum, manifesting itself in muttering delirium, with
occasional paroxysms of greater violence. The victim almost always
apprehends some direful calamity; he imagines his bed to be covered with
loathsome reptiles; he sees the walls of his apartment crowded with foul
specters; and he imagines his friends and attendants to be fiends come to
drag him down to a fiery abyss beneath."--CARPENTER. (See p. 287.)
INFLUENCE UPON THE MENTAL AND MORAL POWERS.--So intimate is the relation
between the body and the mind, that an injury to one harms the other. The
effect of alcoholized blood is to weaken the will. The one habitually
under its influence often shocks us by his indecision and his readiness to
break a promise to reform. The truth is, he has lost, in a measure, his
power of self-control. At last, he becomes physically unable to resist the
craving demand of his morbid appetite.
Other faculties share in this mental wreck. The intellectual vision
becomes less penetrating, the decisions of the mind less reliable, and the
grasp of thought less vigorous. The logic grows muddy. A thriftless,
reckless feeling is developed. Ere long, self-respect is lost, and then
ambition ceases to allure, and the high spirit sinks.
Along with this mental deterioration comes also a failure of the moral
sense. The fine fiber of character undergoes a "degeneration" as certain
as that of the muscles themselves. Broken promises tell of a lowered
standard of veracity, and a dulled sense of honor, quite as much as of an
impaired will. Under the subtle influence of the ever-present poison,
signs of spiritual weakness multiply fast. Conscience is lulled to rest.
Reason is enfeebled. Customary restraints are easily thrown off. The
sensibilities are blunted. There is less ability to appreciate nice shades
of right and wrong. Great moral principles and motives lose their power to
influence. The judgment fools with duty. The future no longer reaches back
its hand to guide the present. The better nature has lost its supremacy.
The wretched victim of appetite will now gratify his tyrannical passion
for drink at any expense of deceit or crime. He becomes the blind
instrument of his insane impulses, and commits acts from which he would
once have shrunk with horror. [Footnote: Richardson sums up the various
diseases caused by alcohol, as follows: "(_a_). Diseases of the brain
and nervous system, indicated by such names as apoplexy, epilepsy,
paralysis, vertigo, softening of the brain, delirium tremens, dipsomania
or inordinate craving for drink, loss of memory, and that general failure
of the mental power, called dementia. (_b_). Diseases of the lungs:
one form of consumption, congestion, and subsequent bronchitis.
(_c_). Diseases of the heart: irregular beat, feebleness of the
muscular walls, dilatation, disease of the valves. (_d_). Diseases of
the blood: scurvy, excess of water or dropsy, separation of fibrin.
(_e_). Diseases of the stomach: feebleness of the stomach,
indigestion, flatulency, irritation, and sometimes inflammation.
(_f_). Diseases of the bowels: relaxation or purging, irritation.
(_g_). Diseases of the liver: congestion, hardening and shrinking,
cirrhosis. (_h_). Diseases of the kidneys: change of structure into
fatty or waxy-like condition and other results leading to dropsy, or
sometimes to fatal sleep. (_i_). Diseases of the muscles: fatty
change in the muscles, by which they lose their power for proper active
contraction. (_j_). Diseases of the membranes of the body: thickening
and loss of elasticity, by which the parts wrapped up in the membrane are
impaired for use, and premature decay is induced."] Sometimes he even
takes a malignant pleasure in injuring those whom Nature has ordained he
should protect. [Footnote: It has been argued that a man should not be
punished for any crime he may commit during intoxication, but rather for
knowingly giving up the reins of reason and conscience, and thus
subjecting himself to the rule of his evil passions. Voluntarily to
stimulate the mind and put it into a condition where it may drive one to
ruin, is very like the act of an engineer who should get up steam in his
engine, and then, having opened the valves, desert his post, and let the
monster go thundering down the track to sure destruction. Certain persons
are thrown into the stage of mental weakness by a single glass of liquor.
How can they be excused when the fact of their peculiar liability lends
additional force to the argument of abstemiousness, and they know that
their only safety lies in total abstinence?--CARPENTER'S
_Physiology._]
2. TOBACCO.
The Constituents of Tobacco Smoke are numerous, but the prominent ones are
carbonic-acid, carbonic-oxide, and ammonia gases; carbon, or soot; and
nicotine. The proportion of these substances varies with different kinds
of tobacco, the pipe used, and the rapidity of the combustion. Carbonic
acid tends to produce sleepiness and headache. Carbonic oxide, in
addition, causes a tremulous movement of the muscles, and so of the heart.
Ammonia bites the tongue of the smoker, excites the salivary glands, and
causes dryness of the mouth and throat. Nicotine is a powerful poison. The
amount contained in one or two strong cigars, if thrown directly into the
blood, would cause death. Nicotine itself is complex, yielding a volatile
substance that gives the odor to the breath and clothing; and also a
bitter extract which produces the sickening taste of an old pipe. In
smoking, some of the nicotine is decomposed, forming pyridine, picoline,
and other poisonous alkaloids. [Footnote: The analysis of tobacco as given
by different authorities varies greatly. The one stated in the text
suffices for the purposes of this chapter. Von Eulenberg names several
other products of the combustion. One hundred pounds of the dry leaf may
yield as high as seven pounds of nicotine. Havana tobacco contains about
two per cent, and Virginia about six per cent.--See JOHNSTON & CHURCH'S
_Chemistry of Common Life_, and MILLER'S _Organic Chemistry_.]
PHYSIOLOGICAL EFFECTS.--The poison of tobacco, set free by the process
either of chewing or smoking, when for the first time it is swept through
the system by the blood, powerfully affects the body. Nausea is felt, and
the stomach seeks to throw off the offending substance. The brain is
inflamed, and headache follows. The motor nerves becoming irritated,
giddiness ensues. Thus Nature earnestly protests against the formation of
this habit. But, after repeated trials, the system adjusts itself to the
new conditions. A "tolerance" of the poison is finally established, and
smoking causes none of the former symptoms. Such powerful substances can
not, however, be constantly inhaled without producing marked changes. The
three great eliminating organs--the lungs, the skin, and the kidneys--
throw off a large part of the products, but much remains in the system.
When the presence of the poison is constant, and especially when the
smoking or chewing is excessive, the disturbance that at first is merely
functional, must necessarily, in many cases at least, lead to a chronic
derangement.
Probably in this, as in the case of other deleterious articles of diet,
the strong and healthy will seem to escape entirely, while the weak and
those predisposed to disease will be injured in direct proportion to the
extent of the indulgence. Those whose employment leads to active, outdoor
work, will show no sign of nicotine poisoning, while the man of sedentary
habits will sooner or later be the victim of dyspepsia, sleeplessness,
nervousness, paralysis, or other organic difficulties. Even where the user
of tobacco himself escapes harm, the law of heredity asserts itself, and
the innocent offspring only too often inherit an impaired constitution,
and a tendency to nervous complaints.
THE VARIOUS DISTURBANCES produced in different individuals and
constitutions by smoking have been summed up by Dr. Richardson as follows:
"(_a_) In the blood, it causes undue fluidity, and change in the red
corpuscles; (_b_) in the stomach, it gives rise to debility, nausea,
and vomiting; (_c_) in the mucous membrane of the mouth, it produces
enlargement and soreness of the tonsils--smoker's sore throat--redness,
dryness, and occasional peeling of the membrane, and either unnatural
firmness and contraction, or sponginess of the gums; and, where the pipe
rests on the lips, oftentimes 'epithelial cancer'; (_d_) in the
heart, it causes debility of the organ, and irregular action; (_e_)
in the bronchial surface of the lungs, when that is already irritable, it
sustains irritation, and increases the cough; (_f_) in the organs of
sense, it produces dilation of the pupils of the eye, confusion of vision,
bright lines, luminous or cobweb specks, and long retention of images on
the retina, with analogous symptoms affecting the ear, viz., inability to
define sounds clearly, and the occurrence of a sharp, ringing noise like a
whistle; (_g_) in the brain, it impairs the activity of the organ,
oppressing it if it be nourished, but soothing it if it be exhausted;
(_h_) it leads to paralysis in the motor and sympathetic nerves, and
to over-secretion from the glands which the sympathetic nerves control."
IS TOBACCO A FOOD?--Here, as in the case of alcohol, the reply is a
negative one. Tobacco manifests no characteristic of a food. It can not
impart to the blood an atom of nutritive matter for building up the body.
It does not add to, but rather subtracts from, the total vital force. It
confers no potential power upon muscle or brain. It stimulates by cutting
off the nervous supply from the extremities and concentrating it upon the
centers. But stimulation is not nourishment; it is only a rapid spending
of the capital stock. There is no greater error than to mistake the
exciting of an organ for its strengthening.
THE INFLUENCE UPON YOUTH.--Here, too, science utters no doubtful voice.
Experience asserts only one conviction. _Tobacco retards the development
of mind and body._ [Footnote: Cigarettes are especially injurious from
the irritating smoke of the paper covering, taken into the lungs, and also
because the poison fumes of the tobacco are more directly inhaled. In case
of the cheap cigarettes often smoked by boys the ingredients used are
harmful, while one revolts at the thought of the filthy materials, refuse
cigar stumps, etc., employed in their manufacture.] The law of nature is
that of steady growth. It can not admit of a daily, even though it be
merely a functional, disturbance that weakens the digestion, that causes
the heart to labor excessively, that prevents the perfect oxidation of the
blood, that interferes with the assimilation, and that deranges the
nervous system. [Footnote: There is one influence of tobacco that every
young man should understand. In many cases, like alcohol, it seems to
blunt the sensibilities, and to make its user careless of the rights and
feelings of others. This is often noticed in common life. We meet
everywhere "devotees of the weed," who, ignoring the fact that tobacco is
disagreeable to many persons, think only of the gratification of their
selfish appetite. They smoke or chew in any place or company. They permit
the cigar fumes to blow into the faces of passers-by. They sit where the
wind carries the smoke of their pipes so that others must inhale it. They
expectorate upon the floor of cars, hotels, and even private homes. They
take no pains to remove the odor that lingers about their person and
clothing. They force all who happen to be near, their companions, their
fellow-travelers, to inhale the nauseating odor of tobacco. Everything
must be sacrificed to the one primal necessity of such persons--a smoke.
Now, a young man just beginning life, with his fortune to make, and his
success to achieve, can not afford to burden himself with a habit that is
costly, that will make his presence offensive to many persons, and that
may perhaps render him less sensitive to the best influences and
perceptions of manhood.] No one has a right thus to check and disturb
continually the regular processes of his physical and mental progress.
Hence, the young man (especially if he be of a nervous, sensitive
organization) who uses tobacco deliberately diminishes the possible energy
with which he might commence the work of life; [Footnote: In the
Polytechnic School at Paris, the pupils were divided into two classes--the
smokers, and the non-smokers. The latter not only excelled on the entrance
examinations, but during the entire course of study. Dr. Decaisne examined
thirty-eight boys who smoked, and found twenty-seven of them diseased from
nicotine poisoning. So long ago as 1868, in consequence of these results,
the Minister of Public Instruction forbade the use of tobacco by the
pupils.
Dr. Gihon, medical director of the Naval Academy at Annapolis, in his
report for 1881, says: "The most important matter in the health history of
the students is that relating to tobacco, and its interdiction is
absolutely essential to their future health and usefulness. In this view I
have been sustained by my colleagues, and by all sanitarians in civil and
military life whose views I have been able to obtain."] while he comes
under the bondage of a habit that may become stronger than his will, and
under the influence of a narcotic that may beguile his faculties and palsy
his strength at the very moment when every power should be awake.
Another peril still lies in the wake of this masterful poison habit.
Tobacco causes thirst and depression that only too often and naturally
lead to the use of liquor. (See p. 338.)
3. OPIUM.
Opium is the dried juice of the poppy. In Eastern countries, this flower
is cultivated in immense fields for the sake of this product. When a cut
is made in the poppy head, a tiny tear of milky juice exudes, and hardens.
These little drops are gathered and prepared for the market, an acre
yielding, it is said, about twenty-five pounds. Throughout the East, opium
is generally smoked; but in Western countries laudanum and paregoric
(tinctures of opium), and morphine--a powerful alkaloid contained in
opium, are generally used. The drug itself is also eaten.
PHYSIOLOGICAL EFFECT.--Opium, in its various forms, acts directly upon the
nerves, a small dose quieting pain, and a larger one soothing to sleep. It
arouses the brain, and fires the imagination to a wonderful pitch.
[Footnote: So far as its effects are concerned, it matters little in what
form opium is taken, whether solid as in pills, liquid as in laudanum, or
vaporized, as when inhaled from a pipe. The opium slave is characterized
by trembling steps, a curved spine, sunken glassy eyes, sallow withered
features, and often by contraction of the muscles of the neck and fingers.
In the East, when the drug ceases its influence, the opium eater renews it
with corrosive sublimate till, finally, this also fails of effect, and he
gradually sinks into the grave.] The reaction from this unnatural excitant
is correspondingly depressing; and the melancholy, the "overwhelming
horror" that ensues, calls for a renewal of the stimulus. The dose must be
gradually increased to produce the original exhilaration. [Footnote: The
victim of opium is bound to a drug from which he derives no benefits, but
which slowly deprives him of health and happiness, finally to end in
idiocy or premature death. Whatever the victim's condition or surroundings
may be, the opium must be taken at certain times with inexorable
regularity. The liquor or tobacco user can, for a time, go without the use
of these agents, and no regular hours are necessary. During sickness, and
more especially during the eruptive fevers, he does not desire tobacco or
liquor. The opium eater has no such reprieves; his dose must be taken,
and, in painful complications affecting the stomach, a large increase is
demanded to sustain the system. If, in forming the habit, two doses are
taken each day, the victim is obliged to maintain that number. It is the
unceasing, everlasting slavery of regularity that humiliates opium eaters
by a sense of their own weakness.--HUBBARD _on The Opium Habit and
Alcoholism._] The seductive nature of the drug leads the unfortunate
victim on step by step until he finds himself fast bound in the fetters of
one of the most tyrannical habits known to man.
To go on is to wreck all one's powers--physical and mental. To throw off
the habit, requires a determination that but few possess. Yet even when
the custom is broken, the system is long in recovering from the shock.
There seems to be a failure of every organ. The digestion is weakened,
food is no longer relished, the muscles waste, the skin shrivels, the
nervous centers are paralyzed, and a premature old age comes on apace. De
Quincey, four months after he had cast away the opium bonds, wrote, "Think
of me as one still agitated, writhing, throbbing, palpitating, shattered."
No person can be too careful in the use of laudanum, paregoric, and
morphine. They may be taken on a physician's prescription as a sedative
from racking pain, [Footnote: Many persons learn to inject morphine
beneath the skin by means of a "hypodermic syringe." The operation is
painless, and seems an innocent one. It throws the narcotic directly into
the circulation, and relief from pain is often almost instantaneous. But
the danger of forming the opium habit is not lessened, and the effect of
using the drug in this form for a long time is just as injurious as opium
smoking itself. Opium in one of its forms enters largely into the
composition of many of the painkillers and patent medicines so freely
advertised for domestic use in the present day, and for this reason the
greatest care is needed in having recourse to any of them. Taken, perhaps,
in the first instance, to alleviate the torments of neuralgia or
toothache, what proves to be a remedy soon becomes a source of
gratification, which the wretchedness that follows on abstinence renders
increasingly difficult to lay aside. The same must be said of bromide of
potassium and hydrate of chloral, frequently resorted to as a remedy for
sleeplessness: the system quickly becomes habituated to their use, and
they can then be relinquished only at the cost of much suffering. Indeed,
the last mentioned of these two drugs obtains over the mind a power which
may be compared to that of opium, and is, moreover, liable to occasion the
disease known as chloralism, by which the system ultimately becomes a
complete wreck. Looking at the whole question of the medicinal use of
narcotics, it is perhaps not too much to say that they should never be
employed except with the authority of a competent medical adviser.--
_Chambers's Journal_.] but if followed up for any length of time, the
powerful habit may be formed ere one is aware. Then comes the opium
eater's grave, or the opium eater's struggle for life!
4. CHLORAL HYDRATE.
CHLORAL HYDRATE is a drug frequently used to cause sleep. It leaves behind
no headache or lassitude, as is often the case with morphine. It is,
however, a treacherous remedy. It is cumulative in its effects, _i.
e._, even a small and harmless dose, persisted in for a long period,
may produce a gradual accumulation of evil results that in the end will
prove fatal.
THE PHYSIOLOGICAL EFFECT of its prolonged use is very marked. The appetite
becomes capricious. The secretions are unnatural. Nausea and flatulency
often ensue. Then the nervous system is involved. The heart is affected.
Sleep, instead of responding to the drug, as at first, is broken and
disturbed. The eyesight fails. The circulation is enfeebled, and the pulse
becomes weak, rapid, and irregular. There is a tendency to fainting and to
difficult respiration. Sometimes the impoverished blood induces a disease
resembling scurvy, the ends of the fingers ulcerate, and the face is
disfigured by blotches. An excessive dose may result in death.
Prolonged habitual use of chloral hydrate tends to debase the mind and
morals of the subject in the same manner as indulgence in alcohol, ether,
or chloroform.
5. CHLOROFORM.
CHLOROFORM is an artificial product generally obtained, by distillation,
from a mixture of chloride of lime, water, and alcohol. It was discovered
in 1831 by Samuel Guthrie, of Sackett's Harbor, New York. It is a
colorless, transparent volatile liquid, with a strong ethereal odor.
PHYSIOLOGICAL EFFECT.--Chloroform is a powerful anęsthetic, which, when
inhaled, causes a temporary paralysis of the nervous system, and thus a
complete insensibility to pain. There is great peril attending its use,
even in the hands of the most skillful and experienced practitioners. It
is sometimes prescribed by a physician, and afterward (as in the case of
laudanum, morphine, and chloral) the sufferer, charmed with the release
from pain and the peaceful slumber secured, buys the Lethean liquid for
himself. Its use soon becomes an apparent necessity. The craving for the
narcotic at a stated time is almost irresistible. The patient, compelled
to give up the use of chloroform, will demand, entreat, pray for another
dose, in a heartrending manner, never to be forgotten. Paleness and
debility, the earliest symptoms, are followed by mental prostration.
Familiarity with this dangerous drug begets carelessness, and its victims
are frequently found dead in their beds, with the handkerchief from which
they inhaled the volatile poison clutched in their lifeless hands.
6. COCAINE.
Cocaine is an alkaloid prepared from the erythroxylon coca, a shrub, five
or six feet high, found wild in the mountainous regions of Ecuador and
Peru, where it is also cultivated by the natives. The South American
Indians, for centuries, have chewed coca leaves as a stimulant, but the
highly poisonous principle, now called cocaine, to which the plant owes
its peculiar effects, was not discovered till 1859. Within a few years
this drug has come into favor as an agent to produce local anęsthesia, and
has proved exceedingly valuable in surgical operations upon the eye and
other sensitive organs. It has already, however, been diverted from its
legitimate use as a benefaction, and to the other evils of the day is now
added the "cocaine habit," which is, perhaps, even more dangerous and
difficult to abandon than either the alcohol or the opium habit.
PHYSIOLOGICAL EFFECT.--Applied locally, cocaine greatly lessens and even
annihilates pain. Taken internally, it acts as a powerful stimulant to the
nervous system, its physiological action being similar to that of theine
(p. 170), caffeine, and theobromine. Used hypodermically, its immediate
effect, says one to whom it was thus administered, is to cause "great
pallor of countenance, profuse frontal perspiration, sunken eyes, enlarged
pupils, lessened sensitiveness of the cornea and conjunctiva, lowered
arterial tension, and a feeble pulse and heart beat. Under its influence I
could not reason. Everything seemed to run through my brain, and in vain I
summoned all my will power to overcome an overwhelming sleepiness." A few
doses of this drug will in some persons produce temporary insanity. Used
to excess, it leads to permanent madness or idiocy. "Cocaine," says a
writer in the _Medical Review_, "is a dangerous therapeutic toy not to
be used as a sensational plaything. If it should come into as general use
as the other intoxicants of its class, it will help to fill the asylums,
inebriate and insane."
PRACTICAL QUESTIONS.
1. Why is the pain of incipient hip disease frequently felt in the knee?
2. Why does a child require more sleep than an aged person?
3. When you put your finger in the palm of a sleeping child, why will he
grasp it?
4. How may we strengthen the brain?
5. What is the object of pain?
6. Why will a blow on the stomach sometimes stop the heart?
7. How long will it take for the brain of a man six feet high to receive
news of an injury to his foot, and to reply?
8. How can we grow beautiful?
9. Why do intestinal worms sometimes affect a child's sight?
10. Is there any indication of character in physiognomy?
11. When one's finger is burned, where is the ache?
12. Is a generally closed parlor a healthful room?
13. Why can an idle scholar read his lesson and at the same time count the
marbles in his pocket?
14. In amputating a limb, what part, when divided, will cause the keenest
pain?
15. What is the effect of bad air on nervous people?
16. Is there any truth in the proverb that "he who sleeps dines"?
17. What does a high, wide forehead indicate?
18. How does indigestion frequently cause a headache?
19. What is the cause of one's foot being "asleep"? [Footnote: Here the
nervous force is prevented from passing by compression. Just how this is
done, or what is kept from passing, we can not tell. If a current of
electricity were moving through a rubber tube full of mercury, a slight
squeeze would interrupt it. These cases may depend on the same general
principle, but we can not assert it.--HUXLEY. The tingling sensation
caused by the compression is transferred to the foot, whence the nerve
starts.]
20. When an injury to the nose has been remedied by transplanting skin
from the forehead, why is a touch to the former felt in the latter?
21. Are closely curtained windows healthful?
22. Why, in falling from a height, do the limbs instinctively take a
position to defend the important organs?
23. What causes the pylorus to open and close at the right time?
24. Why is pleasant exercise most beneficial?
25. Why does grief cause one to lose his appetite?
26. Why should we never study directly after dinner?
27. What produces the peristaltic movement of the stomach?
28. Why is a healthy child so restless and full of mischief?
29. Why is a slight blow on the back of a rabbit's neck fatal?
30. Why can one walk and carry on a conversation at the same time?
31. What are the dangers of overstudy?
32. What is the influence of idleness upon the brain?
33. State the close relation which exists between physical and mental
health and disease.
34. In what consists the value of the power of habit?
35. How many pairs of nerves supply the eye?
36. Describe the reflex actions in reading aloud.
37. Under what circumstances does paralysis occur?
38. If the eyelids of a profound sleeper were raised, and a candle brought
near, would the iris contract?
39. How does one cough in his sleep?
40. Give illustrations of the unconscious action of the brain.
41. Is chewing tobacco more injurious than smoking?
42. Ought a man to retire from business while his faculties are still
unimpaired?
43. Which is the more exhaustive to the brain, worry or severe mental
application?
44. Is it a blessing to be placed beyond the necessity for work?
45. Show how anger, hate, and the other degrading passions are destructive
to the brain. [Footnote: "One of the surest means for keeping the body and
mind in perfect health consists in learning to hold the passions in
subservience to the reasoning faculties. This rule applies to every
passion. Man, distinguished from all other animals by the peculiarity that
his reason is placed above his passions to be the director of his will,
can protect himself from every mere animal degradation resulting from
passionate excitement. The education of the man should be directed not to
suppress such passions as are ennobling, but to bring all under
governance, and specially to subdue those most destructive passions,
anger, hate, and fear."]
46. Are not amusements, to repair the waste of the nervous energy,
especially needed by persons whose life is one of care and toil?
47. Is not severe mental labor incompatible with a rapidly growing body?
48. How shall we induce the system to perform all its functions regularly
49. How does alcohol interfere with the action of the nerves?
50. What is the general effect of alcohol upon the character?
51. Does alcohol tend to produce clearness and vigor of thought?
52. What is the general effect of alcohol on the muscles?
53. Does alcohol have any effect on the bones? The skin?
54. What is the cause of the "alcoholic chill"?
55. Show how alcohol tends to develop man's lower, rather than his higher,
nature.
56. When we wish really to strengthen the brain, should we use alcohol?
57. Why is alcohol used to preserve anatomical specimens?
58. What is meant by an inherited taste for liquor?
59. Ought a person to be punished for a crime committed during
intoxication?
60. Should a boy ever smoke?
61. To what extent are we responsible for the health of our body?
62. Why does alcohol tend to collect in the brain?
63. Does the use of alcohol tend to increase crime and poverty?
VIII.
THE SPECIAL SENSES.
"See how yon beam of seeming white
Is braided, out of seven-hued light;
Yet in those lucid globes no ray
By any chance shall break astray.
Hark, how the rolling surge of sound,
Arches and spirals circling round,
Wakes the hush'd spirit through thine ear
With music it is heaven to hear."
HOLMES.
"Let us remember that if we get a glimpse of the details of natural
phenomena, and of those movements which constitute life, it is not in
considering them as a whole, but in analyzing them as far as our limited
means will permit. In the vibrations of the globe of air which surrounds
our planet, as in the undulations of the ether which fills the immensity
of space, it is always by molecules which are intangible for us, put in
motion by nature, always by the infinitely little, that she acts in
exciting the organs of sense, and she has modeled these organs in a
proportion which enables them to partake in the movement which she
impresses upon the universe. She can paint with equal facility on a
fraction of a line of space on the retina, the grandest landscape or the
nervelets of a rose leaf; the celestial vault on which Sirius is but a
luminous point, or the sparkling dust of a butterfly's wing; the roar of
the tempest, the roll of thunder, the echo of an avalanche, find equal
place in the labyrinth whose almost imperceptible cavities seem destined
to receive only the most delicate sounds."
_ _
| 1. THE TOUCH...| 1. Description of the Organ.
| |_2. Its Uses.
| _
| 2. THE TASTE...| 1. Description of the Organ.
| |_2. Its Uses.
| _
| 3. THE SMELL...| 1. Description of the Organ.
| |_2. Its Uses.
| _ _
| | 1. Description of the | a. _External Ear._
| | Organ...............| b. _Middle Ear._
| 4. THE HEARING.| |_c. _Internal Ear._
| | 2. How we Hear
| |_3. Hygiene of the Ear.
| _
| | 1. Description of the Organ.
| | 2. Eyelids, and Tears.
| | 3. Structure of the Retina.
|_5. THE SIGHT...| 4. How we see.
| 5. The Use of the Crystalline Lens.
| 6. Near and Far Sight.
| 7. Color Blindness.
|_8. Hygiene of the Eyes.
THE SPECIAL SENSES
1. TOUCH.
DESCRIPTION.--Touch is sometimes called the "common sense," since its
nerves are spread over the whole body. It is most delicate, however, in
the point of the tongue and the tips of the fingers. The surface of the
cutis is covered with minute, conical projections called _papillę_
(Fig. 24). [Footnote: In the palm of the hand, where there are at least
twelve thousand in a square inch, we can see the fine ridges along which
they are arranged.] Each one of these papillę contains its tiny nerve
twigs, which receive the impression and transmit it to the brain, where
the perception is produced.
USES.--Touch is the first of the senses used by a child. By it we obtain
our idea of solidity, and throughout life rectify all other sensations.
Thus, when we see anything curious, our first desire is to handle it.
The sensation of touch is generally relied upon, yet, if we hold a marble
in the manner shown in Fig. 57, it will seem like two marbles; and if we
touch the fingers thus crossed to our tongue, we shall seem to feel two
tongues. Again, if we close our eyes and let another person move one of
our fingers over a plane surface, first lightly, then with greater
pressure, and then lightly again, we shall think the surface concave.
FIG. 57.
[Illustration:]
This organ is capable of wonderful cultivation. The physician acquires by
practice the _tactus eruditus_, or learned touch, which is often of
great service, while the delicacy of touch possessed by the blind almost
compensates the loss of the absent sense. [Footnote: The sympathy between
the different organs shows how they all combine to make a home for the
mind. When one sense fails, the others endeavor to remedy the defect. It
is touching to see how the blind man gets along without eyes, and the deaf
without ears. Cuthbert, though blind, was the most efficient polisher of
telescopic mirrors in London. Saunderson, the successor of Newton as
professor of mathematics at Cambridge, could distinguish between real and
spurious medals. There is an instance recorded of a blind man who could
recognize colors. The author knew one who could tell when he was
approaching a tree, by what he described as the "different feeling of the
air."] (See p. 346.)
2. TASTE.
DESCRIPTION.--This sense is located in the papillę of the tongue and
palate. These papillaę start up when tasting, as you can see by placing a
drop of vinegar on another person's tongue, or your own before a mirror.
The velvety look of this organ is given by hair-like projections of the
cuticle upon some of the papillę. They absorb the liquid to be tasted, and
convey it to the nerves. [Footnote: An insoluble substance is therefore
tasteless.] The back of the tongue is most sensitive to salt and bitter
substances, and, as this part is supplied by the ninth pair of nerves
(Fig. 56), in sympathy with the stomach, such flavors, by sympathy, often
produce vomiting. The edges of the tongue are most sensitive to sweet and
sour substances, and as this part is supplied by the fifth pair of nerves,
which also goes to the face, an acid, by sympathy, distorts the
countenance.
FIG. 58.
[Illustration: _The Tongue, showing the several kinds of Papillę--the
conical_ (D) _the whip like_ (K, I), _the circumvallate or entrenched_
(H, L); E, F, G, _nerves;_ C, _glottis._--LANKESTER.]
THE USE OF THE TASTE was originally to guide in the selection of food;
but this sense has become so depraved by condiments and the force of habit
that it would be a difficult task to tell what are one's natural tastes.
3. SMELL. [Footnote: The sense of smell is so intimately connected with
that of taste that we often fail to distinguish between them. Garlic,
vanilla, coffee and various spices, which seem to have such distinct
taste, have really a powerful odor, but a feeble flavor.]
DESCRIPTION.--The nose, the seat of the sense of smell, is composed of
cartilage covered with muscles and skin, and joined to the skull by small
bones. The nostrils open at the back into the pharynx, and are lined by a
continuation of the mucous membrane of the throat. The olfactory nerves
(first pair, Fig. 55) enter through a sieve-like, bony plate at the roof
of the nose, and are distributed over the inner surface of the two
olfactory chambers. (See p. 346.) The object to be smelled need not touch
the nose, but tiny particles borne on the air enter the nasal passages.
[Footnote: Three quarters of a grain of musk placed in a room will cause a
powerful smell for a considerable length of time without any sensible
diminution in weight, and the box in which musk has been placed retains
the perfume for almost an indefinite period. Haller relates that some
papers which had been perfumed by a grain of ambergris, were still very
odoriferous after a lapse of forty years. Odors are transported by the air
to a considerable distance. A dog recognizes his master's approach by
smell even when he is far away; and we are assured by navigators that the
winds bring the delicious odors of the balmy forests of Ceylon to a
distance of ten leagues from the coast. Even after making due allowance
for the effects of the imagination, it is certain that odors act as an
excitant on the brain, which may be dangerous when long continued. They
are especially dreaded by the Roman women. It is well known that in
ancient times the women of Rome indulged in a most immoderate use of baths
and perfumes; but those of our times have nothing in common with them in
this respect; and the words of a lady are quoted, who said on admiring an
artificial rose, "It is all the more beautiful that it has no smell." We
are warned by the proverb not to discuss colors or tastes, and we may add
odors also. Men and nations differ singularly in this respect. The
Laplander and the Esquimaux find the smell of fish oil delicious. Wrangel
says his compatriots, the Russians, are very fond of the odor of pickled
cabbage, which forms an important part of their food; and asaftida, it is
said, is used as a condiment in Persia, and, in spite of its name, there
are persons who do not find its odor disagreeable any more than that of
valerian.--_Wonders of the Human body_.]
FIG. 59.
[Illustration: A, b, c, d, _interior of the nose, which is lined by a
mucous membrane;_ n, _the nose;_ e, _the wing of the nose;_
q, _the nose bones;_ o, _the upper lip;_ g, _section of the
upper jaw-bone;_ h, _the upper part of the mouth, or hard palate;_
m, _frontal bone of the skull;_ k, _the ganglion or bulb of the
olfactory nerve in the skull, from which are seen the branches of the
nerve passing in all directions._]
THE USES of the sense of smell are to guide us in the choice of our food,
and to warn us against bad air, and unhealthy localities. (See p. 348.)
4. HEARING.
DESCRIPTION.--The ear is divided into the _external_, _middle_,
and _internal_ ear.
1. _The External Ear_ is a sheet of cartilage curiously folded for
catching sound. The auditory canal, _B_, or tube of this ear trumpet,
is about an inch long. Across the lower end is stretched _the membrane
of the tympanum_ or drum, which is kept soft by a fluid wax.
FIG. 60.
[Illustration: _The Ear._]
2. _The Middle Ear_ is a cavity, at the bottom of which is the
Eustachian tube, _G_, leading to the mouth. Across this chamber hangs
a chain of three singular little bones, _C_, named from their shape
the _hammer_, the _anvil_, and the _stirrup_. All together
these tiny bones weigh only a few grains, yet they are covered by a
periosteum, are supplied with blood vessels, and they articulate with
perfect joints (one a ball-and-socket, the other a hinge), having synovial
membranes, cartilages, ligaments, and muscles.
3. _The Internal Ear_, or labyrinth, as it is sometimes called from
its complex character, is hollowed out of the solid bone. In front, is the
vestibule or antechamber, _A_, about as large as a grain of wheat;
from it open three _semicircular canals_, _D_, and the winding
stair of the _cochlea_, or snail shell, _E_. Here expand the
delicate fibrils of the auditory nerve. Floating in the liquid which fills
the labyrinth is a little bag containing hair-like bristles, fine sand,
and two ear stones (_otoliths_). All these knocking against the ends
of the nerves, serve to increase any impulse given to the liquid in which
they lie. Finally, to complete this delicate apparatus, in the cochlea are
minute tendrils, named the fibers of Corti, from their discoverer. These
are regularly arranged,--the longest at the bottom, and the shortest at
the top. Could this spiral plate, which coils two and a half times around,
be unrolled and made to stand upright, it would form a beautiful
microscopic harp of three thousand strings. If it were possible to strike
these cords as one can the keyboard of a piano, he could produce in the
mind of the person experimented upon every variety of tone which the ear
can distinguish.
HOW WE HEAR.--Whenever one body strikes another in the air, waves are
produced, just as when we throw a stone into the water a series of
concentric circles surrounds the spot where it sinks. These waves of air
strike upon the membrane. This vibrates, and sends the motion along the
chain of bones in the middle ear to the fluids of the labyrinth. Here
bristles, sand, and stones pound away, and the wondrous harp of the
cochlea, catching up the pulsations, [Footnote: The original motion is
constantly modified by the medium through which it passes. The bristles,
otoliths, and Cortian fibers of the ear, and the rods and cones of the eye
(p. 239) serve to convert the vibrations into pulsations which act as
stimuli of the appropriate nerve. The molecular change thus produced in
the nerve fibers is propagated to the brain.--See _Popluar
Physics_, p. 182.] carries them to the fibers of the auditory nerve,
which conveys them to the brain, and gives to the mind the idea of sound.
CARE OF THE EAR.--The delicacy of the ear is such that it needs the
greatest care. Cold water should not be allowed to enter the auditory
canal. If the wax accumulate, never remove it with a hard instrument, lest
the delicate membrane be injured, but with a little warm water, after
which turn the head to let the water run out, and wipe the ear dry. The
hair around the ears should never be left wet, as it may chill this
sensitive organ. If an insect get in the external ear, pour in a little
oil to kill it, and then remove with tepid water. The object of the
Eustachian tube is to admit air into the ear, and thus equalize the
pressure on the membrane. If it become closed by a cold, or if, from any
cause, the pressure be made unequal, so as to produce an unpleasant
feeling in the ear, relief may often be obtained by grasping the nose and
forcibly swallowing. (See p. 350.)
5. SIGHT.
FIG. 61.
[Illustration: _The Eye._]
DESCRIPTION.--The eye is lodged in a bony cavity, protected by the
overhanging brow. It is a globe, about an inch in diameter. The ball is
covered by three coats--(l) the _sclerotic_, _d_, a tough, horny
casing, which gives shape to the eye, the convex, transparent part in
front forming a window, the _cornea_, _d_; (2) the _choroid_, _e_, a
black lining, to absorb the superfluous light [Footnote: Neither white
rabbits nor albinos have this black lining, and hence their sight is
confused.] and (3) the _retina_, _b_, a membrane in which expand fibers
of the _optic nerve_, _o_. The _crystalline lens_, _a_, brings the rays
of light to a focus on the retina. The lens is kept in place by the
ciliary processes, _g_, arranged like the rays in the disk of a passion
flower. Between the cornea and the crystalline lens is a limpid fluid
termed the _aqueous humor_; while the _vitreous humor_--a transparent,
jelly-like liquid fills the space (_h_) back of the crystalline lens.
The pupil, _k_, is a hole in the colored, muscular curtain, _i_, the
_iris_ (rainbow). (See p. 352.)
FIG. 62.
[Illustration: _The Eyelashes and the Tear Glands._]
EYELIDS AND TEARS.--The eyelids are close-fitting shutters to screen the
eye. The inner side is lined with a mucous membrane that is exceedingly
sensitive, and thus aids in protecting the eye from any irritating
substance. The looseness of the skin favors swelling from inflammation or
the effusion of blood, as in a "black eye." The eyelashes serve as a kind
of sieve to exclude the dust, and, with the lids, to shield against a
blinding light. Just within the lashes are oil glands, which lubricate the
edges of the lids, and prevent them from adhering to each other. The tear
or _lachrymal_ gland, _G_, is an oblong body lodged in the bony
wall of the orbit. It empties by several ducts upon the inner surface, at
the outer edge of the upper eyelid. Thence the tears, washing the eye, run
into the _lachrymal lake_, _D_, a little basin with a rounded
border fitted for their reception. On each side of this lake two canals,
_C_, _C_, drain off the overplus through the duct, _B_,
into the nose. In old age and in disease, these canals fail to conduct the
tears away, and hence the lachrymal lake overflows upon the face.
FIG. 63.
[Illustration: _Structure of the Retina._]
STRUCTURE OF THE RETINA.--In Fig. 63 is shown a section of the retina,
greatly magnified, since this membrane never exceeds 1/80 an inch in
thickness. On the inner surface next to the vitreous humor, is a lining
membrane not shown in the cut. Next to the choroid and comprising about
1/4 the entire thickness of the retina, is a multitude of transparent,
colorless, microscopic rods, _a_, evenly arranged and packed side by
side, like the seeds on the disk of a sunflower. Among them, at regular
intervals, are interspersed the cones, _b_. Delicate nerve fibers
pass from the ends of the rods and cones, each expanding into a granular
body, _c_, thence weaving a mesh, _d_, and again expanding into
the granules, _f_. Last is a layer of fine nerve fibers, _g_,
and gray, ganglionic cells, _h_, like the gray matter of the brain,
whence filaments extend into _i_, the fibers of the optic nerve. (See
p. 354.)
The layer of rods and cones is to the eye what the bristles, otoliths, and
Cortian fibers are to the ear. Indeed, the nerve itself is insensible to
light. At the point where it enters the eye, there are no rods and cones,
and this is called the _blind spot_. A simple experiment will
illustrate the fact. Hold this book directly before the face, and, closing
the left eye, look steadily with the right at the left-hand circle in Fig.
64. Move the book back and forth, and a point will be found where the
right-hand circle vanishes from sight. At that moment its light falls upon
the spot where the rods and cones are lacking.
FIG. 64.
[Illustration:]
HOW WE SEE.--There is believed to be a kind of universal atmosphere,
termed _ether_, filling all space. This substance is infinitely more
subtle than the air, and occupies its pores, as well as those of all other
substances. As sound is caused by waves in the atmosphere, so light is
produced by waves in the ether. A lamplight, for example, sets in motion
waves of ether, which pass in through the pupil of the eye, to the retina,
where the rods and cones transmit the vibration through the optic nerve to
the brain, and then the mind perceives the light. (Note, p. 236.)
THE USE OF THE CRYSTALLINE LENS. [Footnote: The uses of the eye and ear
are dependent upon the principles of Optics and Acoustics. They are
therefore best treated in Physics.]--A convex lens, as a common burning
glass, bends the rays of light which pass through it, so that they meet at
a point called the _focus_. The crystalline lens converges the rays
of light which enter the eye, and brings them to a focus on the retina.
[Footnote: The cornea and the humors of the eye act in the same manner as
the crystalline lens, but not so powerfully.] The healthy lens has a power
of changing its convexity so as to adapt [Footnote: The simplest way of
experimenting on the "adjustment of the eye" is to stick two stout needles
upright into a straight piece of wood,--not exactly, but nearly in the
same straight line, so that, on applying the eye to one end of the piece
of wood, one needle (A) shall be seen about six inches off, and the other
(B) just on one side of it, at twelve inches distance. If the observer
looks at the needle B he will find that he sees it very distinctly, and
without the least sense of effort; but the image of A is blurred, and more
or less double. Now, let him try to make this blurred image of the needle
A distinct. He will find he can do so readily enough, but that the act is
accompanied by a sense of fatigue. And in proportion as A becomes
distinct, B will become blurred. Nor will any effort enable him to see A
and B distinctly at the same time.--HUXLEY.] itself to near and to distant
objects. (See Fig. 66.)
FIG. 65.
[Illustration: _Diagram showing how an image of an object is formed upon
the Retina by the Crystalline Lens._]
NEAR AND FAR SIGHT.--If the lens be too convex, it will bring the rays to
a focus before they reach the retina; if too flat, they will reach the
retina before coming to a focus. In either case, the sight will be
indistinct. A more common defect, however, is in the shape of the globe of
the eye, which is either flattened or elongated. In the former case (see
_G_, Fig. 67), objects at a distance can be seen most distinctly--
hence that is called farsightedness. [Footnote: This should not be
confounded with the long sight of old people, which is caused by the
stiffness of the ciliary muscles, whereby the lens can not adapt itself to
the varying distances of objects.] In the latter, objects near by are
clearer, and hence this is termed nearsightedness. Farsightedness is
remedied by convex glasses; nearsightedness, by concave. When glasses will
improve the sight they should be worn; [Footnote: Dr. Henry W. Williams,
the celebrated ophthalmologist, says that, in some cases, glasses are more
necessary at six or eight years of age than to the majority of healthy
eyes at sixty. Sometimes children find accidentally that they can see
better through grandmother's spectacles. They should then be supplied with
their own.] any delay will be liable to injure the eyes, by straining
their already impaired power. Cataract is a disease in which there is an
opacity of the crystalline lens or its capsules, which obscures the
vision. The lens may be caused to be absorbed, or may be removed by a
skillful surgeon and the defect remedied by wearing convex glasses.
FIG. 66.
[Illustration: _Adjustment of the Crystalline Lens._--A, _for far
objects, and_ B, _for near._]
FIG. 67.
[Illustration: _Diagram illustrating the position of the Retina._--B,
_in natural sight;_ G, _in far sight; and_ C, _in near sight._]
COLOR-BLIND PERSONS receive only two of the three elementary color
sensations (green, red, violet). The spectrum appears to them to consist
of two decidedly different colors, with a band of neutral tint between.
The extreme red end is invisible, and a bright scarlet and a deep green
appear alike. They are unable to distinguish between the leaves of a
cherry tree and its fruit by the color of the two, and see no difference
between blue and yellow cloth. Whittier, the poet, it is said, could not
tell red from green unless in direct sunlight. Once he patched some
damaged wall paper in his library by matching a green vine in the pattern
with one of a bright autumnal crimson. This defect in the eye is often
unnoticed, and many railway accidents have doubtless happened through an
inability to detect the color of signal lights.
CARE OF THE EYES.--The shape of the eye can not be changed by rubbing and
pressing it, as many suppose, but the sight may thus be fatally injured.
Children troubled by nearsightedness should not lean forward at their
work, as thereby the vessels of the eye become overcharged with blood.
They should avoid fine print, and try, in every possible way, to spare
their eyes. If middle age be reached without especial difficulty of sight,
the person is comparatively safe. Most cases of squinting are caused by
longsightedness, the muscles being strained in the effort to obtain
distinct vision. In childhood, it may be cured by a competent surgeon, who
will generally cut the muscle that draws the eye out of place.
After any severe illness, especially after measles, scarlatina, or typhoid
fever, the eyes should be used with extreme caution, since they share in
the general debility of the body, and recover their strength slowly.
Healthy eyes even should never be used to read fine print or by a dim
light. Serious injury may be caused by an imprudence of this kind. Reading
upon the cars is also a fruitful source of harm. The lens, striving to
adapt itself to the incessantly varying distance of the page, soon becomes
wearied. Whenever the eyes begin to ache, it is a warning that they are
being overtaxed and need rest.
Objects that get into the eye should be removed before they cause
inflammation; rubbing in the meantime only irritates and increases the
sensitiveness. If the eye be shut for a few moments, so as to let the
tears accumulate, and the upper lid be then lifted by taking hold of it at
the center, the cinder or dust is often washed away at once. Trifling
objects can be removed by simply drawing the upper lid as far as possible
over the lower one; when the lid flies back to its place, the friction
will detach any light substance. If it becomes necessary, turn the upper
lid over a pencil, and the intruder may then be wiped off with a
handkerchief. "Eye-stones" are a popular delusion. When they seem to take
out a cinder, it is only because they raise the eyelid, and allow the
tears to wash it out. No one should ever use an eyewash, except by medical
advice. The eye is too delicate an organ to be trifled with, and when any
disease is suspected, a reliable physician should be consulted. This is
especially necessary, since, when one eye is injured, the other, by
sympathy, is liable to become inflamed, and perhaps be destroyed.
When reading or working, the _light should be at the left side, or at
the rear; never in front_.
The constant increase of defective eyesight among the pupils in our
schools is an alarming fact. Dr. Agnew considers that our schoolrooms are
fast making us a spectacle-using people. Nearsightedness seems to increase
from class to class, until in the upper departments, there are sometimes
as high as fifty per cent of the pupils thus afflicted. The causes are
(1), desks so placed as to make the light from the windows shine directly
into the eyes of the scholars; (2), cross lights from opposite windows;
(3), insufficient light; (4), small type that strains the eyes; and (5),
the position of the pupil as he bends over his desk or slate, causing the
blood to settle in his eyes. All these causes can be remedied; the
position of the desks can be changed; windows can be shaded, or new ones
inserted; books and newspapers that try the eyes can be rejected; and
every pupil can be taught how to sit at study.
PRACTICAL QUESTIONS.
1. Why does a laundress test the temperature of her flatiron by holding it
near her cheek?
2. When we are cold, why do we spread the palms of our hands before the
fire?
3. What is meant by a "furred tongue"?
4. Why has sand or sulphur no taste?
5. What was the origin of the word palatable?
6. Why does a cold in the head injure the flavor of our coffee?
7. Name some so-called flavors that are really sensations of touch.
8. What is the object of the hairs in the nostrils?
9. What use does the nose subserve in the process of respiration?
10. Why do we sometimes hold the nose when we take unpleasant medicine?
11. Why was the nose placed over the mouth?
12. Describe how the hand is adapted to be the instrument of touch.
13. Besides being the organ of taste, what use does the tongue subserve?
14. Why is not the act of tasting complete until we swallow?
15. Why do all things have the same flavor when one's tongue is "furred"
by fever?
16. Which sense is the more useful--hearing or sight?
17. Which coat is the white of the eye?
18. What makes the difference in the color of eyes?
19. Why do we snuff the air when we wish to obtain a distinct smell?
20. Why do red-hot iron and frozen mercury (-40°) produce the same
sensation?
21. Why can an elderly person drink tea which to a child would be
unbearably hot?
22. Why does an old man hold his paper so far from his eyes?
23. Would you rather be punished on the tips of your fingers than on the
palm of your hand?
24. What is the object of the eyelashes? Are the hairs straight?
25. What is the use of winking?
26. When you wink, do the eyelids touch at once along their whole length?
Why?
27. How many rows of hairs are there in the eyelashes?
28. Do all nations have eyes of the same shape?
29. Why does snuff taking cause a flow of tears?
30. Why does a fall cause one to "see stars"?
31. Why can we not see with the nose, or smell with the eyes?
32. What causes the roughness of a cat's tongue?
33. Is the cuticle essential to touch?
34. Can one tickle himself?
35. Why does a bitter taste often produce vomiting?
36. Is there any danger in looking "crosseyed" for fun?
37. Should schoolroom desks face a window?
38. Why do we look at a person to whom we are listening attentively?
39. Do we really feel with our fingers?
40. Is the eye a perfect sphere? (See Fig. 61.)
41. How often do we wink?
42. Why is the interior of a telescope or microscope often painted black?
43. What is "the apple of the eye"?
44. What form of glasses do old people require?
45. Should we ever wash our ears with cold water?
46. What is the object of the winding passages in the nose?
47. Can a smoker tell in the dark, whether or not his cigar is lighted?
48. Will a nerve reunite after it has been cut?
49. Will the sight give us an idea of solidity? [Footnote: A case occurred
a few years ago, in London, where a friend of my own performed an
operation upon a young woman who had been born blind, and, though an
attempt had been made in early years to cure her, it had failed. She was
able just to distinguish large objects, the general shadow, as it were,
without any distinct perception of form, and to distinguish light from
darkness. She could work well with her needle by the touch, and could use
her scissors and bodkin and other implements by the training of her hand,
so to speak, alone Well, my friend happened to see her, and he examined
her eyes, and told her that he thought he could get her sight restored; at
any rate, it was worth a trial. The operation succeeded; and, being a man
of intelligence and quite aware of the interest of such a case, he
carefully studied and observed it; and he completely confirmed all that
had been previously laid down by the experience of similar cases. There
was one little incident which will give you an idea of the education which
is required for what you would suppose is a thing perfectly simple and
obvious. She could not distinguish by sight the things that she was
perfectly familiar with by the touch, at least when they were first
presented to her eyes. She could not recognize even a pair of scissors.
Now, you would have supposed that a pair of scissors, of all things in the
world, having been continually used by her, and their form having become
perfectly familiar to her hands, would have been most readily recognized
by her sight; and yet she did not know what they were; she had not an idea
until she was told, and then she laughed, as she said, at her own
stupidity. No stupidity at all; she had never learned it, and it was one
of those things which she could not know without learning. One of the
earliest cases of this kind was related by the celebrated Cheselden, a
surgeon of the early part of last century. Cheselden relates how a youth
just in this condition had been accustomed to play with a cat and a dog;
but for some time after he attained his sight he never could tell which
was which, and used to be continually making mistakes. One day, being
rather ashamed of himself for having called the cat the dog, he took up
the cat in his arms and looked at her very attentively for some time
stroking her all the while; and in this way he associated the impression
derived from the touch, and made himself master (so to speak) of the whole
idea of the animal. He then put the cat down, saying: "Now, puss, I shall
know you another time."--CARPENTER.]
50. Why can a skillful surgeon determinate the condition of the brain and
other internal organs by examining the interior of the eye? [Footnote:
This is done by means of an instrument called the ophthalmoscope. Light is
thrown into the eye with a concave mirror, and the interior of the organ
examined with a lens.]
51. Is there any truth in the idea that the image of the murderer can be
seen in the eye of the dead victim?
52. What is the length of the optic nerve? _Ans_. About three fourths
of an inch.
53. Why does an injury to one eye generally affect the other eye?
_Ans_. The optic nerves give off no branches in passing from their
origin in two ganglia situated between the cerebrum and the cerebellum,
and their termination in the eyeballs; but, in the middle of their course,
they _decussate_, or unite in one mass. The fibers of the two nerves
here pass from side to side, and intermingle. The two ganglia are also
united directly by fibers. Thus the eyes are not really separate organs of
sight, but a kind of double organ to perform, a single function.
IX.
HEALTH AND DISEASE.--DEATH AND DECAY.
"Health is the vital principle of bliss."
THOMSON.
"There are three wicks to the lamp of a man's life: brain, blood, and
breath. Press the brain a little, its light goes out, followed by both the
others. Stop the heart a minute, and out go all three of the wicks. Choke
the air out of the lungs, and presently the fluid ceases to supply the
other centers of flame, and all is soon stagnation, cold, and darkness."
O. W. HOLMES.
"Calmly he looked on either Life, and here
Saw nothing to regret, or there to fear;
From Nature's temp'rate feast rose satisfy'd,
Thank'd Heaven that he had lived, and that he died."
POPE.
HEALTH AND DISEASE.--DEATH AND DECAY.
VALUE OF HEALTH.--The body is the instrument which the mind uses. If it be
dulled or nicked, the effect of the best labor will be impaired. The
grandest gifts of mind or fortune are comparatively valueless unless there
be a healthy body to use and enjoy them. The beggar, sturdy and brave with
his outdoor life, is really happier than the rich man in his palace with
the gout to twinge him amid his pleasures. The day has gone by when
delicacy is considered an element of beauty. Weakness is timid and
irresolute; strength is full of force and energy. Weakness walks or
creeps; strength speeds the race, wins the goal, and rejoices in the
victory.
FALSE IDEAS OF DISEASE.--It was formerly supposed that diseases were
caused by evil spirits, who entered the body, and deranged its action.
Incantations, spells, etc., were resorted to in order to drive them out.
By others, disease was thought to come arbitrarily, or as a special
visitation of an overruling power. Hence, it was to be removed by fasting
and prayer. Modern science teaches us that disease is not a thing, but a
state. When our food is properly assimilated, the waste matter promptly
excreted, and all the organs work in harmony, we are well; when any
derangement of these functions occurs, we are sick. Sickness is discord,
as health is concord. If we abuse or misuse any instrument, we impair its
ability to produce a perfect harmony. A suffering body is simply the
penalty of violated law.
PREVENTION OF DISEASE.--Doubtless a large proportion of the ills which now
afflict and rob us of so much time and pleasure might easily be avoided. A
proper knowledge and observance of hygienic laws would greatly lessen the
number of such diseases as consumption, catarrh, gout, rheumatism,
dyspepsia, etc. There are parts of England where one half the children die
before they are five years old. Every physiologist knows that at least
nine tenths of these lives could be saved by an observance of the simple
laws of health. Professor Bennet, in a lecture at Edinburgh, estimated
that one hundred thousand persons die annually in Great Britain from
causes easily preventable.
With the advance of science, the causes of many diseases have been
determined. Vaccination has been found to prevent or mitigate the ravages
of smallpox. Scurvy, formerly so fatal among sailors that it was deemed "a
mysterious infliction of Divine Justice against which man strives in
vain," is now entirely avoided by the use of vegetables or lime juice.
Cholera, whose approach still strikes dread, and for which there is no
known specific, is but the penalty for filthy streets, bad drainage, and
overcrowded tenements, and may be controlled, if not prevented, by
suitable sanitary measures. It was, no doubt, the intention that we should
wear out by the general decay of all the organs, [Footnote: So long as the
phenomena of waste and repair are in harmony--so long, in other words, as
the builder follows the scavenger--so long man exists in integrity and
repair--just, indeed, as houses exist. Derange nutrition, and at once
degeneration, or rather let us say, alteration begins. Alas! that we are
so ignorant that there are many things about our house, which, seeing
them, weaken, we know not how to strengthen. About the brick and the
mortar, the frame and the rafters, we are not unlearned; but within are
many complexities, many chinks and crannies, full in themselves of
secondary chinks and crannies, and these so small, so deep, so recessed,
that it happens every day that the destroyer settles himself in some place
so obscure, that, while he kills, he laughs at defiance. You or I meet
with an accident in our watch. We consult the watchmaker, and he repairs
the injury. If we were all that watchmakers, like ourselves, should be, a
man could be made to keep time until he died from old age or annihilating
accident. This I firmly and fully believe.--_Odd Hours of a
Physician_.] rather than by the giving out of any single part, and that
all should work together harmoniously until the vital force is exhausted.
CURE OF DISEASE.--The first step in the cure of any disease is to obey the
law of health which has been violated. If medicine be taken, it is not to
destroy the disease, since that is not a thing to be destroyed, but to
hold the deranged action in check while nature repairs the injury, and
again brings the system into harmonious movement. This tendency of nature
is our chief reliance. The best physicians are coming to have diminished
confidence in medicine itself, and to place greater dependence upon
sanitary and hygienic measures, and upon the efforts which nature always
makes to repair injuries and soothe disordered action. They endeavor only
to give to nature a fair chance, and sometimes to assist her by the
intelligent employment of proper medicines. The indiscriminate use of
patent nostrums and sovereign remedies of whose constituents we know
nothing, and by which powerful drugs are imbibed at haphazard, can not be
too greatly deprecated. When one needs medicine, he needs also a competent
physician to advise its use.
DEATH AND DECAY.--By a mystery we can not understand, life is linked with
Back to Full Books
|