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APPLIED PHYSIOLOGY
INCLUDING
THE EFFECTS OF ALCOHOL
AND NARCOTICS
BY
FRANK OVERTON, A.M., M.D.
LATE HOUSE SURGEON TO THE CITY HOSPITAL, NEW YORK
INTERMEDIATE GRADE
^c
NEW YORK-:- CINCINNATI •: • CHICAGO
AMERICAN BOOK COMPANY
Copyright, 1897, by
AMERICAN BOOK COMPANY
APPLIED PHYSIOLOGY
E-P »7
PREFACE
The author of this intermediate grade of Applied Physi-
ology has designed the work to be not merely an intro-
duction to the study of anatomy and physiology, but a
complete elementary work in itself, giving a clear picture
of how each organ of the body performs its work.
In presenting hygienic facts to pupils before they
have an elementary knowledge of anatomy and physiology,
there is a violation of pedagogical principles. The laws
of healthful living cannot be grasped without this elemen-
tary knowledge of the human machine to which the laws
apply. Advice to a pupil will have an effect in direct pro-
portion to the confidence reposed in the teacher. New
environments and duties demand new applications of laws.
Every business man is often compelled to break common
hygienic laws in regard to eating, exposure, and overwork.
Thus mere advising conduces but little toward intelligent
living. On the other hand, prohibition arouses in children
a desire to do the forbidden thing, especially if it be a rule
insisted upon at school. Moreover, the unavoidable incon-
sistencies of teachers themselves will upset the pupil's
confidence in all laws. For these reasons dogmatic hygi-
enic advice is avoided, but anatomical and physiological
facts are simply stated and developed.
By way of example, however, it has seemed wise to indi-
cate detailed hygienic applications of physiology and anat-
omy along a single line, leaving it to teachers to apply the
same principles to other abuses of the body in answer to
3
4 PREFACE
the numerous questions which every class will undoubtedly
ask. For this purpose the subject of alcohol and tobacco
has been selected, both because of their wide-spread abuse,
and also because of their universal effect upon all parts
of the body. In this way the pupil will be made to realize
the wide-spread results of abusing even a single part of
the body. Great care has been exercised to make the dis-
cussion of stimulants and narcotics correct in every par-
ticular, and to bring it fully into conformity with the most
recent temperance legislation.
The cuts are mostly selected from the author's advanced
work, but a few original ones have been added. The
microscopic appearances of tissues have been especially
emphasized.
Practical demonstrations have been omitted; for, without
explanations, they are meaningless to pupils of the inter-
mediate grades. Yet, without demonstrations the intelli-
gent study of unfamiliar parts is impossible. Teachers
will find an outline of a complete, yet simple, series of
experiments in the author's advanced work.
With the desire to supply a long-felt want, the author
presents these results of experience and thought to teach-
ers and pupils.
Patchogue, N. Y.
CONTENTS
CHAPTER PAGE
I. Cells 7
II. Digestion . . *5
III. Foods 26
IV. Intemperance and Poisons 35
V. Tobacco 44
VI. Alcohol 49
VII. The Blood and its Circulation .... 60
VIII. Bleeding, Wounds, and Disease Germs ... 72
IX. Respiration 80
X. Ventilation, Heat, and Clothing .... 92
XI. The Skin and Kidneys 104
XII. The Nerves and Spinal Cord . . . .114
XIII. The Brain 122
XIV. Narcotics and. the Nervous System . . . 132
XV. The Senses 143
XVI. Bones 155
XVII. Muscles 165
Glossary I7S
Index l%3
5
APPLIED PHYSIOLOGY
CHAPTER I
CELLS
1. The ameba. — In moist earth there lives a little ani-
mal called the ameba. It is so small that you cannot see
it without a magnifying glass many times as strong as the
best spectacles. When you do see it you will not know
that it is an animal, for it has neither eyes, nor head, nor
arms, nor legs. It is simply like a lump of jelly. But if
you look a minute, you will see it put forth some part of
its body like a finger to take a little lump of food. This
finger is also a mouth and swallows the food. Then the
An ameba, sketched at intervals of ten seconds (x 400).
finger becomes a stomach and changes the food to blood
so that the animal can grow. When it wants to go for a
walk, it puts forth a finger, and then the whole body rolls
itself into the finger, and thus it moves forward. So the
little ameba can make an arm, or a mouth, or a stomach,
or a leg, wherever and whenever it wants to.
7
8
APPLIED PHYSIOLOGY
An animal that can make any part of its body anew to
suit itself should be very prosperous and happy. In fact,
the ameba does grow so fast that in a day or two it thinks
itself big enough to become two animals, and so it splits
itself into two parts, and each half goes off by itself as a
full-grown ameba.
2. Cells. — Man has a separate part of the body set
aside to do each kind of work. He has legs which carry
him to his food, and arms with which to get the food, and
a mouth with which to eat it. But these parts do not
make the real man, for
some men lose their arms
and legs and yet remain
men. The real man is the
mind which lives in the
body and makes the arms,
and legs, and mouth do as
it wants them to do. But
a man's arm or his leg, or
any other part of his body,
is itself made of millions
of little living things like
the ameba. We call each
Some of these cells are
Each has
Cells from the human body ( X 200) .
a A colored cell from the eye.
b A white blood cell.
c A connective tissue cell.
d A cell from the lining of the mouth.
e Liver cells.
f A muscle cell from the intestine.
of these living things a cell.
long, some flat, and some of other shapes,
the form best fitted for the work it does, but all are ex-
ceedingly small. They are held in place by fine strings
called connective tissue. By scraping the skin, cells can
be removed from its surface. They look like flour.
3. Mind rules the cells. — The mind takes good care
of these cells. When we eat we feed the cells, and we
breathe so that each cell can get a little air. To repay the
mind for its care the cells all work together like good ser-
CELLS 9
vants to do just as the mind tells them. Thus, when the
mind wants to walk, all the cells of the legs get themselves
under the body and push the body ahead. They do it so
willingly that we do not think how hard they have to
work. When the mind wishes to stop, it tells the cells of
the legs that they need not work any more until it wishes
to move again.
Sometimes it is very hard for the mind to teach the cells
to work just as they should and to keep still when they
ought. Boys and girls go to school so that they may learn
how to make the cells obey the mind. We ought to take
Water, 12 gallons
Albumin or gelatine, 20 lb. Fat, 10 lb.
Substances of which the body is composed.
good care of our bodies because the living cells of which
they are composed make such good servants for the mind.
4. Of what the cells are made : water. — About three
fourths of each cell of the body is water. Water is found
even in teeth and in bone. All animals must have water
to drink. Even the driest food, like crackers, has a great
deal of water, while other kinds, like meat and potatoes,
are nearly three fourths water. In all, a man swallows
two or three quarts of water each day.
5. Albumin. — Next to water something which is like
10
APPLIED PHYSIOLOGY
the white of an egg forms the most of the body. This
substance is called albumin, because when boiled it be-
comes white and hard. It is the living part of cells and
must be eaten to sustain their life. It is found in all food,
both animal and vegetable. We eat about four and a half
ounces of albumin each day.
6. Fat. — Oil, or fat, is found in little pockets between
the cells. It is in a liquid form, and becomes hard only
when the body cools
after death. When we
boil a piece of meat, the
pockets are softened so
that the fat runs out and
floats upon the top of
the water. Fat must be
eaten in order that the
cells of the body may
be healthy, but they can
live for a long time with-
out it, for the fat of the
body is made out of albumin, and not from the fat which
is eaten. The fat around the cells is like a cushion which
protects the cells and keeps them warm. It also makes
the body round and handsome. Fat is found in all com-
mon food. We eat about three ounces each day.
7. Starch and sugar. — Starch and sugar also enter the
body as food. Only a little of these is really found in the
body at once, for it is soon used up in warming the body.
Starch is found in all vegetable food in the form of small
grains. Cooking in hot water makes these grains swell
and burst. Then they dissolve in water and form a
paste. In the young plant there is but little sugar and
a great deal of starch, but when the plant ripens, the
Fat tissue (X ioo).
Connective tissue cells form pockets in which
the liquid fat is stored.
CELLS I i
I
starch changes to sugar. When starch is eaten, it is also
changed to sugar. So starch and sugar are the same kind
of food. About one
quarter of a pound of
starch or sugar must
be eaten each day.
8. Minerals. — In
the body there are also
minerals, such as lime,
iron, potash, and salt. fflmt Starch grains (x 400).
When the body is \§gr fl|0f potato. b, of corn,
burned, these are left
behind as ashes. The lime stiffens the bones. Iron is
found in the blood and coloring matter of the body.
Potash and salt are found all through the body. These
minerals are found in all food, for all leave ashes when
burned. Yet some salt must be added to food.
(9. Food. — Everything which makes the cells and fluids
of the body is composed of either water, albumin, fat,
sugar, or minerals. These sustain life, and are. foods. All
other kinds of substances are harmful or poisonous.
10. Oxidation. — All kinds of food are constantly being
eaten, and yet only water and mineral substances leave
the body in anything like the form in which they entered.
What becomes of the rest ?
When a piece of meat is put into a hot fire, it bursts
into a flame and burns to smoke and ashes. By its burn-
ing it gives off heat, and makes the fire hotter. If the
draft of the stove is closed tightly, the fire does not burn,
for a stream of air must flow steadily into the fire. The
air is one fifth oxygen gas. This oxygen unites with the
meat and forms two invisible gases — carbonic acid gas
and vapor of water. These gases are the smoke. The
12
APPLIED PHYSIOLOGY
ashes are the mineral parts of the meat. This is what
takes place in every fire. We call it oxidation. If the
fire is under the boiler of an engine, the heat is used in
changing the water to steam. The steam can then be
made to do work.
11. Oxidation within the body. — Besides meat and other
kinds of food, air is also taken inside of our bodies. Car-
bonic acid gas and water are given off in the breath, our
bodies are warmed, and
they perform work, as a
steam engine does. The
body is really an engine
directed by the mind. The
lungs are the boilers, while
the nose is the draft where
the oxygen enters and the
carbonic acid gas and
water pass out. Both the
food and the cells of the
body are oxidized. By the
oxidation the same heat is
produced as though the food were burned outside the body,
but it occurs so slowly that no flame is produced. Most
of the heat simply warms the body. The muscles and
brain form the engine which changes the rest of the heat
to work. All the power of a man's body is derived from
the heat of oxidation. Running, speaking, and thinking
are different kinds of work, and depend upon the heat of
oxidation for power.
12. Use of food. — The greater part of the fuel for oxi-
dation is supplied by the food before it reaches the cells
of the body. The cells themselves are also slowly oxidized.
In course of time their substance is completely burned up,
Diagram of burning or oxidation in a
stove.
CELLS
13
and its place supplied by new food. So the object in tak-
ing food is both to supply the cells with what was burned
from them, and also to furnish fuel for the greater part of
the oxidation within the body.
Water and mineral substances are not oxidized, but only
add weight to the cells of the body. Fat and starch give
only heat. Albumin gives both weight and heat, for it
both becomes a part of
the living cells and also
is oxidized. So anything
which gives either weight
or heat to the body is
food.
13. Relation of plants
to animals. — Man's food
comes both from animals
and from vegetables, but
animals feed upon vege-
tables, or else eat other
animals which eat vege-
tables. Vegetables feed
upon substances in the
soil and air. The burned-
up parts of man and ani-
mals go back to the soil
and air and become food for plants. Thus plants build
the burned products of man's body into food, which can
be used once more by man. So year after year the
food makes the round from the soil to the plants, and then
to animals and man, and back again to the soil. A plant
lives on the soil and air. An animal cannot live on these,
but must eat what plants have formed from them. This
makes the real difference between plants and animals.
Carbonic Acid Gas
in the airaoing
into the lea/
in the soil
Diagram of the restoration of oxygen to
the air after oxidation, and of the rebuild-
ing of burned material into living forms.
APPLIED PHYSIOLOGY
SUMMARY
i. The body is made of separate living cells, each like a
little animal.
2. Each cell obeys the mind and works for the benefit of
the body.
3. Cells are made of five things ; viz., water, albumin, fat,
starch, or sugar, and mineral substances.
4. These five substances are formed outside the body, and
are food for man.
5. Oxygen is also taken inside the body, and burns up or
oxidizes the food and some of the substances of the
cells.
6. By the oxidation within the body heat is produced.
7. The cells of the body form an engine which changes
some of the heat to work.
8. What we eat either is added to the cells of the body, or
else is oxidized to produce heat and work.
9. Food is anything which, when swallowed, gives weight
or heat to the body.
CHAPTER II
DIGESTION
14. Digestion. — We have seen how the little amebas can
take food into any part of their bodies, and then can change
it so that it becomes a living part of themselves. Each
ameba has to seek its own food, and to take it just as it
is found. The cells of our bodies have their food pre-
pared for use and brought to them by a few of the cells
of the body set aside for that special work. This food is
the blood. All food eaten must become a part of the blood
before it can nourish the body.
The preparation of food so that the cells can use it is
called digestion. The object of digestion is to separate
food from its hard and waste parts, and then to soften
and dissolve it so that it becomes a liquid and can flow
with the blood.
15. Cooking. — Man usually begins digestion outside of
his body by cutting his food into pieces and heating or
cooking it. By cooking most kinds of albumin are changed
to a jellylike or solid form, like a cooked Qgg, but some
kinds, like the connective tissue which binds the cells to-
gether, are softened. Cooking should leave food so soft
that it can be chewed easily. Usually the longer food is
cooked, the softer it becomes.
Cooking softens starch grains and causes them to swell
and burst, and finally to dissolve in water, forming a thin
paste. Man cannot digest raw starch, and so it must be
'5
16 APPLIED PHYSIOLOGY
cooked if it is to be of any use to his body. Cooking
does not change sugar.
Cooking simply melts fat, but does not change it, unless
the heat is great enough to burn it. But in meat and
vegetables, cooking softens the pockets of albumin in which
the fat is stored, and sets it free, so that it floats upon the
water. In this way pure lard and tallow are made.
Cooking develops the taste of food so that it is more
agreeable to the body. It also destroys many poisons in
food.
16. Ways of cooking. — Man applies heat in cooking in
three ways. He boils the food in water, or surrounds it
with heat in a hot oven, or exposes one side at once to the
heat, as in broiling. It makes little difference how it is
done, so long as it is done well. Cooked food should taste
good and be either soft, or else brittle, so that it can be
chewed fine. If food is tough or doughy, so that it cannot
be chewed well, it is surely not well cooked.
After the food is cooked we put it upon a plate and cut
it into fine bits. This saves the mouth a great deal of
work and keeps us from eating too fast. Every one should
take time to cut his food into small pieces before eating it.
17. Mouth digestion. — After the food is cooked, man
takes it into his mouth, and there continues its digestion
by grinding it between his teeth and rolling it about with
his tongue and cheeks until it is in fine particles. At the
same time he mixes it with a watery fluid so that it is like
a thin paste.
18. The teeth. — The teeth are bony pegs set into the
jaw bones. Those in the front part of each bone are
sharp in order to bite off lumps of food. Those in the
back part of the mouth are flat so as to grind the food to
pieces. Between the ages of six and thirteen years a
DIGESTION
17
A tooth cut open.
a enamel.
b dentine or bone.
c pulp cavity con-
taining blood
tubes and
nerves.
d cement.
child loses his first set of teeth and gets a whole new set
with eight additional ones.
19. Structure of teeth. — Through the center of each
tooth there runs a small tube which contains a nerve and a
blood tube. The outside of the part above
the jaw is covered with a very hard sub-
stance called enamel^ which protects the
inner part from decay and injury. Biting
hard things, like nuts or wood, often breaks
the enamel, and then the tooth decays.
When the decay reaches the nerve, the
tooth aches and becomes very tender.
20. Care of the teeth. — Bits of food
sometimes get between the teeth, and if left
there make the breath smell bad, and often
cause the teeth to decay. A wooden tooth-
pick used after each meal will best remove
these bits of food.
A gray substance, called tartar, often collects upon the
teeth, making them rough and dirty. One should keep
this from forming by brushing the teeth with a tooth-
brush and water each morning and night. Tobacco-chew-
ing stains the teeth almost black and causes them to decay
quickly.
21. The jaws. — The upper jaw is a part of the bone of
the face and cannot be moved. The lower jaw is a half
circle of bone with its two back ends turned up. It can
be moved up and down, forward and backward, and side-
wise. By its movements it causes the teeth to act upon
the food in every direction.
22. The cheeks and tongue. — The cheeks and tongue
are made up mostly of muscles which can roll the food
about in any direction. They have a fine sense of feeling,
OV. PHYSIOL. (INTER.) — 2
18
APPLIED PHYSIOLOGY
so as to be able to judge of the position of the food and to
tell when it is chewed enough.
23. Mucous membrane. — The mouth, as well as every
other cavity of the body,
^^^^^^^^^^® a has a thin lining called
^^^s^ss^.-^^^^^ mucous membrane, which
looks like a fine, soft skin.
At the lips, nose, and other
openings, this lining joins
the skin so that it is im-
possible to tell where the
one begins and the other
ends. It is really a part
of the skin turned inside
the body. Mucous mem-
brane is made of a net-
work of cells and fibers,
which is covered with an
unbroken layer of firm
cells called epithelium.
24. Glands. — In each
mucous membrane are
tiny tubes which open
upon its surface. Each
tube is lined with cells
of epithelium like those
upon the surface of the
The cells
lining each tube produce
a slightly slimy fluid
called mucus. They pour just enough of it upon the
surface of the membrane to moisten it.
A tube or collection of tubes whose cells can form a
Diagram of glands.
sa epithelium upon the surface of a mucous
membrane.
b the epithelium continued into a simple tube.
c the epithelium continued into a simple
pocket.
d the epithelium continued into a series of membrane.
branching tubes and pockets.
b, c, and d are glands.
DIGESTION
19
continuous supply of a substance is called a gland. All
mucous membranes contain enough mucous glands to
keep their surfaces moist. In addition some mucous
membranes also contain glands which produce other sub-
stances.
25. Salivary glands. — Upon the sides of the mouth are
the openings of several small tubes through which a fluid
called the saliva is always enter-
ing to moisten the mouth. While
one is eating, more saliva flows,
so that over a quart is produced
each day. Each tube runs deep
into the cheeks and suddenly
divides again and again like the
branches of a tree, so that the
finest tubes cannot be seen with-
out a microscope. Each tube
is made of cells set edge to edge.
These cells produce the saliva
from the blood.
Each bunch of tubes is rolled
together, forming a mass about the size of a walnut. Each
mass is called a salivary gland. There is a salivary gland
in front of each ear, and two under each side of the jaw.
In mumps these glands swell and produce lumps around
the lower jaw.
26. The saliva. — The saliva is a watery fluid which
flows very freely when anything is chewed. Saliva has a
little power to change starch to sugar, but its main use is
to dissolve the food into a thin paste which can be swal-
lowed. The food should always be chewed so long as any
lumps can be felt.
27. The pharynx and swallowing. — When the food has
A salivary gland (X 200).
tube of epithelium forming the
gland, cut lengthwise.
tubes cut crosswise.
connective tissue binding the
tubes in place.
20
APPLIED PHYSIOLOGY
been chewed to a paste, it is collected into a mass upon
the back of the tongue, and pushed into a muscular bag
called the pharynx. The pharynx has seven openings.
Two into the nose and two into the ears can be closed by
raising the back part of the roof of the mouth. An open-
ing into the windpipe
can be closed by a cover
called the epiglottis. The
opening into the mouth
can be closed by two
curtains, which slide
across the back of the
tongue and meet in the
middle. The opening
into the tube leading to
the stomach is the only
one left. When food
reaches the pharynx, its
muscles squeeze the food
into the open tube lead-
ing to the stomach.
Thus food is swallowed.
28. The esophagus. —
The tube leading from
the pharynx to the stom-
ach is called the esoph-
agus. The esophagus
squeezes the food so that it is forced in the direction
of the stomach. Each swallow of water in a horse's
esophagus can be seen to run up its neck on its way to the
stomach. Man's esophagus would look the same if it were
near the surface.
29. The stomach. — The inside of the body is divided
Diagram of the beginning of swallowing.
a top of tongue.
b pharynx.
c morsel of food. •
d sliding door of the front of the pharynx.
e soft palate.
/ epiglottis.
DIGESTION
21
into two parts by a sheet of muscle called the diaphragm.
The upper part is called the chest or thorax, and holds the
esophagus, lungs, and heart. The lower part is called the
abdomen, and holds the stomach, intestine, liver, pancreas,
and kidneys. The stomach is a thin bag of muscle lying
upon the left side of
the body, just under the
lowest ribs. It is lined
with mucous membrane,
which contains very
small tubes. These
tubes are glands which
produce a fluid called
the gastric juice. The
stomach squeezes and
stirs the food about in
a gentle manner, and
mixes it with the gastric
juice, so that in the
course of an hour or two
the food is ground and
mixed, much as it was
in the mouth.
\30. The gastric juice.
— The glands produce
about three quarts of
gastric juice daily. It
is mostly water, but it
contains a small amount
of a sour substance called hydrochloric acid, and of a white
substance called pepsin. These two substances eat away
or dissolve albumin, so that it becomes soft, and finally
fully dissolves in the water of the gastric juice. Digested
Diagram of second part of swallowing.
a top of tongue arched backward and up-
ward.
b pharynx.
c morsel of food pushed into the pharynx by
the back of the tongue.
d sliding doors of the pharynx which have
come together in the middle.
e soft palate lifted upward to shut off the nose.
f epiglottis folded downward to close the
larynx.
22
APPLIED PHYSIOLOGY
albumin is called peptone. The stomach has no effect
upon starch or fat. Only a small amount of the albumin
is really changed to peptone by
the gastric juice, for every few
moments the opening leading
from the stomach permits a
small quantity of food to pass
out. So food does not remain
with the gastric juice long
enough to be fully digested.
The mixture of food and gastric
juice leaving the stomach is
called chyme.
31. The intestine. — When
food leaves the stomach it passes
into a coil of a thin muscular
tube called the intestine. The
intestine is about twenty-five
feet in length. Its upper four fifths is about an inch in
diameter, while the lowest one fifth is about twice this size.
Both parts slowly squeeze the food along, mixing it with
three fluids, which act upon the fond and change it to a
liquid.
32. Intestinal fluids. — First. In the mucous membrane
of the intestine are small tubelike glands. They pour out
a liquid called the intestinal juice. The intestinal juice is
small in quantity, and does not have much effect upon the
food.
Second. Behind the stomach is a gland called the pan-
creas or sweetbread. Each day it pours into the intestine
about a quart of a liquid called the pancreatic juice. This
juice does most of the work of digesting food. It acts
upon the albumin left by the stomach, and changes it to
Organs of the chest and abdomen
a lungs. d stomach.
b heart. e liver.
c diaphragm. / intestine.
DIGESTION
23
liquid peptone. It changes starch to sugar, but far more
powerfully than the saliva. It causes fat to become broken
into fine particles, which will mix with water. It also
changes some fat to soap.
Third. Above the stomach there is a large red gland
called the liver. Each day it pours into the intestine
about a quart of a yellow and
bitter liquid called bile. Bile
itself does but little of the
work of digestion, but its pres-
ence doubles the power of the
pancreatic juice. Bile is a
waste substance, but on its
way out of the body it helps
in the work of building up the
body.
33. Movements of the intes-
tine. — Like the mouth and
stomach, the intestine mixes
the food with the juices, and
forces it along its tube.
Gastric glands in the stomach
(X 200).
A s a epithelium of the surface of the
stomach.
food goes farther and farther b epithelium lining the tubes of the
down, it becomes * more and g^nds.
c connective tissue between the tubes.
more liquid, until at the end
only such things as very large lumps of food, or husks and
peelings, remain solid. The food now looks like milk,
with undigested particles floating in it. It is still as much
outside the body as though it were held in the closed
mouth. It must pass through the wall of the intestine
and enter the blood stream before it can feed the cells.
s 34. How food gets into the blood. — Many blood tubes
lie almost upon the surface of the intestine, while many
more lie upon tiny fingers called villi, which reach from
24 APPLIED PHYSIOLOGY
the sides of the intestine into the liquid food. Peptone
and sugar easily soak into these blood tubes, and are car-
ried to the liver. There the liver cells change the peptone
back to a form of albumin much like that which was eaten.
It is then fit food for the cells, and is sent to all parts of
the body with the blood. The liver cells also change the
sugar to a kind of starch. This is soon oxidized in the
liver, and heat is produced for the use of the body.
Fat is soaked up by another set of tubes called lacteals.
The lacteals begin in the villi, and finally empty the fat
into a blood tube in the neck. The fat is then carried to
the lungs, where it is oxidized so as to produce heat for
the body.
35. Action of the bowels. — As the food slowly passes
down the intestine, its liquid parts soak into the blood
tubes, so that by the time it reaches the large intestine
most of its water and all its useful parts have been removed,
and only waste matter is left, which is driven on and out
of the body. These waste matters should be expelled
regularly at least once a day. If it is done at a certain
time, the intestine will form the habit of always acting at
that time. If the waste matters are not given off, we have
headaches, and may become sick, for they poison the body.
36. Use of the liver. — If poisons are swallowed, they
too are taken up by the blood tubes, and are carried to the
liver. The liver cells strive to keep these poisons from
going farther along the blood tubes, and thus they protect
the body against bad food. So the liver has very impor-
tant uses. When it gets out of order, it sends but little
bile to digest the food. It lets poisons from the intestine
pass by, and does not change the digested food to a form
suited to the cells of the body. The result is a kind of
sickness called biliousness.
DIGESTION 25
37. Digestion of water and minerals. — Water and mim
erals need no digestion, but are taken up at once by
the blood tubes. Water is always being poured into the
mouth, stomach, and intestine by the glands, but is soon
taken up again by the blood tubes. In all, about twelve
quarts of water enter and leave these parts each day. As
only two or three quarts are swallowed each day, the same
water is used over and over again.
* SUMMARY
1. Making food a liquid so that it can reach and feed the
cells of the body is digestion.
2. Cooking begins digestion by softening the food.
3. The mouth grinds the food and mixes it with the
saliva which changes some starch to sugar.
4. The stomach mixes the food with the gastric juice,
and continually stirs it about. The gastric juice
dissolves some of the albumin to peptone.
5. In the intestine the bile and pancreatic juice change
albumin to peptone and starch to sugar, and break
the fat into fine particles.
6. Digested albumin and sugar soak into the blood tubes
and are carried to the liver. Digested fat soaks
into the lacteals, and is emptied into the blood
stream in the neck.
7. The liver makes the albumin a part of the blood.
8. The liver changes the sugar back to a form of starch
and oxidizes it, producing heat.
9. The liver also strains out poisons from the blood.
10.. Digested fat is carried to the lungs, and is there
oxidized.
II. Water and mineral substances enter the blood without
being digested.
CHAPTER III
FOODS
38. Kinds of substances in food. — A few hours after
eating, all the food is used by the cells of the body, and
then they ask for more through the feelings of hunger and
thirst. To satisfy these feelings, man uses many different
kinds of food, all containing either water, albumin, fat,
starch, or mineral substances.
2 eggs.
I lb. of bread. 3 pints of water.
Food required daily by a healthy man.
ik pints of milk.
39. Why sugar is fattening. — The fat of the body is
formed from albumin. When much sugar is eaten, it is
oxidized in place of the albumin and fat. These remain
and make the body heavier. So we say that sugar is
fattening. But sugar gives only heat and power to the
body. Albumin gives weight, heat, and power, while
water and minerals give weight only.
26
FOODS 27
40. Difference in foods. — Water and mineral substances
are the same everywhere, except as other things are mixed
with them. They are found alike in all foods, and so far
as they are concerned, it makes little difference what kinds
of food are eaten. On the other hand, there are many
kinds of albumin, fat, and starch, and it
is the differences among these that make 'o^Oo
1 t re r 1 ° ft 0cU. 0»Ooo
the difference in foods. 0 O oo0oq00° o
41. Milk. — Milk contains all kinds of d&°d£o°o6°00%
food substances, for it has water, min- 0 ^ 00&£$go0Si>0
erals, albumin, fat, and sugar. More- °0 Oo°°°o9^6 °
over, these substances are in the best Milk as it appears
form for the u*e of the body. So milk under the microscope
. . . . (x 300). The drops
is the most perfect food known, and is are the fat.
the only food which babies can eat.
42. Cheese. — Milk is one eighth solid matter. Of the
solid matter the minerals form but a small part, while
albumin, fat, and sugar each form about one third. The
albumin becomes hard or curdled when the milk turns
sour, and makes the milk like soft jelly. It is also curdled
in the stomach in the first part of digestion. When cur-
dled outside the body and freed from the water of the
milk, it is called cheese. Cheese usually contains the fat
of milk also. It is a valuable food.
43. Cream. — When milk stands for a while, its fat
rises to the top and is called cream. If the cream is
shaken in a churn, the fat collects in a lump called butter.
Cream and butter are the most valuable forms of fat in
food.
44. How to drink milk. — Some persons say that milk
is harmful to them. It is likely to be so when a large
quantity of cold milk is swallowed after a full meal is
eaten. Think how a young animal drinks milk. It takes
28 APPLIED PHYSIOLOGY
it warm, upon an empty stomach, and swallows it very
slowly. If a person will drink warmed milk, in sips,
before he eats, it will rarely harm him. Children espe-
cially will find milk the best kind of food for them.
^ 45. Eggs. — Eggs are about one fifth albumin and one
fifth fat, and the rest is water with a little mineral matter.
They have no starch or sugar, and so are not a perfect
food for man. A perfect chicken can be formed from an
egg, for the hen supplies the heat which, in man, comes
from the sugar.
Eggs are easily digested, and form one of the most
valuable foods in whatever form they are eaten. When
boiled for at least ten minutes they are easily chewed fine,
and are readily digested. Soft-boiled eggs are next in
value.
Eggs which have been kept for some time are not
desirable for food, even though they are not spoiled.
They should always be fresh.
46. Meat. — Meat is the muscle of animals and birds.
It is from one tenth to one fifth albumin, and has less
than that amount of fat. It has some mineral matter,
while the rest is water. It has no starch or sugar, and so
is not a perfect food. But it is a valuable food, especially
for the young. No child can be harmed by eating meat.
In fact, he should have meat or eggs every day.
Meat which is salted or dried or canned becomes hard-
ened so that the digestive juices act upon it less easily.
So for young persons or persons with weak stomachs it is
not desirable for food. Of all the different kinds of meat,
beef is the most easily digested, and pork the least. Most
kinds of fresh fowl and game are easily digested.
47. Fish. — Fish, crabs, oysters, and clams are forms
of meat. If they are fresh and of good quality, they can
FOODS
29
be eaten with as much safety as beef or pork. Raw
oysters are especially valuable for sick people, for the
dark mass which is often thought to be their intestine
is really their liver and helps digest them.
48. Difference between animal and vegetable foods. —
All animal food is more easily digested than vegetable
food, and should be used by children and sick persons.
It contains little or no starch, however, and some vege-
table food must be eaten for the sake of its starch. All
vegetable food contains some albumin and a large amount
of starch or sugar and little fat. It is possible to live a
healthy life while eating only vegetable food, but this is
by no means the best kind of food.
49. Vegetable food. — Bread is about one half starch,
and one fifteenth albumin, and hardly one seventieth fat.
In it the albumin is more easily digested than in any
other kind of vegetable food, yet less so than the albumin
of animal food. It is not a perfect food, for the starch
is in too large amount, but with meat or eggs it is a
perfect food. With milk it is also a valuable food, espe-
cially for the young. Cake is much like bread, but it
contains more sugar.
Potatoes have a large amount of starch and very little
albumin, and no fat. They are good food with meat, but
are hard to digest.
Beans are one fourth albumin and one half starch. For
a strong person they are a valuable food, but weak persons
find it hard to digest them.
Cereals, like corn meal and rice, are from two thirds to
three fourths starch, and only one eighth to one fifteenth
albumin. Only corn contains much fat, but all vegetable
fat is hard to digest, and is of little value as food.
50. Fruit. — Fruit contains some starch and albumin
3<D APPLIED PHYSIOLOGY
and a great deal of sugar ; but all fruit is hard to digest,
and little food is obtained. It is sometimes thought that
the acids and flavors of fruit give some needed substances
to the cells of the body, but their main use is their taste.
Fruit is of use mainly because it is not digested ; but, in
passing down the intestine, it sweeps along food and waste
substances, and thus keeps the intestine clean and in good
condition. A great danger in using fruit is that it may
sour and decay in the intestine just as it does outside the
body.
51. Sweets. — Candy and sweet things of all kinds con-
sist mostly of sugar, which is digested and carried to the
liver. Thus, by eating too much of them, one eats too
much sugar, and then the liver is overworked, and a bilious
attack is produced. Nuts contain a great deal of albumin
and oil, but both are in a form hard to digest.
Green vegetables, such as cabbage, lettuce, and beets,
are like fruit, but contain even less food matters. They
are of value mainly for their taste.
^ 52. Spices. — Spices, such as mustard and cloves, burn
the stomach just as they burn the mouth. They have no
value as food, while by covering the taste of bad food they
may be harmful. Still a little may improve the taste of
food and so assist digestion.
53. Salt. — All the foods named have more than enough
mineral substances, excepting salt, to supply the needs of
the body. Salt is a great aid in the digestion of food. It
also gives an agreeable taste to food. Food which has
no taste can hardly be eaten, and after it is eaten it is as
disagreeable to the stomach as it is to the mouth. Salt
gives food an agreeable flavor. The saliva flows so that
the mouth waters. In the stomach the gastric juice flows
in the same way, and so the meal is easily and quickly
FOODS 31
digested. Fruit, nuts, and similar foods act upon the taste
in the same way as salt.
54. Bad food. — Food which smells or tastes musty or
decayed is always unfit for food and may be poisonous.
Spoiled milk or cream is the worst of all. Young children
and babies should never drink milk which is the least
sour. Moldy bread or meat may cause sickness of the
stomach and great pains in the lower part of the" body.
The food of diseased animals is as bad as spoiled food.
Canned food should not be opened until it is to be eaten,
for it soon spoils when exposed to the air.
Unripe fruit cannot be digested at all unless it is cooked.
Green apples or cherries are not fit for any one. In them
the starch and sugar are like the starch in grass. But by
thorough cooking they may sometimes be made harmless.
-55. Diseased food. — Food may contain disease germs.
Consumption is often caught in this way. Meat is the
most often diseased ; and of meat, pork the most often
contains disease germs. Cooking destroys the germs. So
we should never eat raw meat.
56. Choice of food. — The different kinds of meal and
flour are almost the same in price. Meats, fish, and vege-
tables of the same food value differ greatly in their cost.
The variety of foods, or their good appearance, or their un-
(usually fine taste makes them high-priced. What is called
the best food may look and taste better, but is often no
more nourishing than cheaper food. The cheaper meats
and fish furnish good food at half the cost of the best
kinds. If they are well cooked, they will taste as good as
the best. Plain flour and meal are cheap, but prepared and
ready mixed kinds cost far more and are no better for food.
57. Water. — Water is also a food, but we call it a drink.
Water itself is everywhere the same, but different sub-
32
APPLIED PHYSIOLOGY
stances dissolved in it make it good or bad for use. Really
pure water has a flat taste, and is unfit for drinking. Air
in the water gives it a pleasant taste. Water often dis-
solves lime from the soil so that it does not easily form a
lather with soap. We call such water hard. Rain water
is soft, for it has no lime.
How impurities may get into a well.
, 58. Impure water. — Water dissolves many substances
over which it runs, but only a few of these are harmful.
When it stands in lead pipes for some hours, it dissolves a
little poisonous lead. If the water that has stood in the
pipes is thrown away, the running water will be safe for use.
Almost the only other dangerous substance found in
FOODS
33
water is decaying matter. Decaying slops from the house
or barnyard are very poisonous. They sometimes soak
into the well and poison the family. Disease germs can-
not grow in pure water, but they easily grow in water
containing decayed substances. Sometimes the germs of
typhoid fever get into the water of a well and grow, pro-
ducing the disease in those who drink the water. Water
may be impure even if it tastes good and looks clear and
sparkling. The surest way to keep the water pure is to
locate the well so that no slops or barnyard drainage can
reach it.
59. How to purify water. — If impure water must be
used, the disease germs may be destroyed by boiling it for
ten minutes. This also drives out the air and makes the
water taste flat, but if it stands a few hours, it takes up
air and becomes fit for use. Water can be somewhat
purified by passing it through sand or powdered charcoal
or some other powdered substance. An arrangement for
this purpose is a filter. A filter removes mud and coarse
particles, but it does not take out all the disease germs.
60. Amount of water needed. — A grown person needs
about three quarts of water daily. He will take half of
this with his solid food, leaving about a quart and a half
to be drunk extra. We should drink about this amount of
water daily. The time of drinking is not of great impor-
tance. Some should be taken at meal times, and, if the
meal is eaten slowly, it can do no harm. All drinks, of
course, contain water which should be counted as so much
ordinary water.
61. Tea and coffee. — Tea and coffee are not food, but
they act upon the mind so that the body does not feel tired
when hard work is done. By using a large amount of tea
and coffee it would seem that more work can be done, yet
OV. PHYSIOL. (INTER.) — 3
34 APPLIED PHYSIOLOGY
they do not add to the strength of the body, but only
benumb its tired feelings. A substance which causes the
body to do more work without giving extra strength is
called a stimulant. The old Romans called an ox whip a
stimulus. So a stimulant is anything which acts like a
whip.
62. How much food ? — In all, about one fourth of a
pound of albumin, and a little more than a quarter of
a pound of starch, and a little less than a quarter of a
pound of fat should be eaten each day. What food
shall we select to furnish these substances ? Men live
upon every kind of food, but some foods are better than
others. This bill of fare for the day will give the right
quantity of food :
i lb. of meat, or eggs, or fish ; 2 oz. of butter ;
\ lb. of bread ; 3 pints of water; 1^ pints of milk.
*^ SUMMARY
1. All animal food contains a good quantity of albumin
and fat, and but little starch or sugar.
2. Vegetable foods contain albumin, but it is much harder
to digest than the albumin of animal food.
3. Vegetable food contains some oil, but this is scarcely
digested at all.
4. Vegetable food contains a very large quantity either of
starch or of sugar.
5. The best bill of fare contains animal food to supply
the albumin and fat, and vegetable food to supply
the sugar or starch.
6. Salt is the only mineral substance which needs to be
added to food.
7. Almost any kind of water can be made safe for drink-
ing by boiling it for ten minutes.
CHAPTER IV
INTEMPERANCE AND POISONS
63. Why men are intemperate. — If a man should eat as
nature intended, he would always be strong and healthy.
In caring for animals we feed them only one or two kinds
of food, and are very careful not to overfeed them. If
they have too much food, or too many different kinds of
food, they become sick. We sometimes say that a per-
son has the stomach of an animal, for nothing seems to
hurt him. But if the stomachs of animals were treated as
the stomachs of men are commonly treated, animals would
become sick sooner than men.
Improper eating and improper drinking produce more
ill health than all other causes put together. Many
parents feed their children with sweets and candy. Some
give them tea and coffee, and some give them beer or
wine. These things create a craving which increases its
demands if it is gratified, and thus paves the way for the
desire for strong drink.
Man is surrounded by an abundance of all kinds of good
food, and is given a plenty of time for eating it. Yet, in
spite of his knowledge and opportunities, he often makes
himself sick by his eating and drinking. He is led to do
this by making a wrong use of the very feelings which
should teach him how to eat properly.
64. Hunger and thirst. — Nature has given man signs
so that his mind may know when and what kind of food
35
36 APPLIED PHYSIOLOGY
to eat. The sense of taste is a sure guide as to the kind
of food that is needed. Man never tires of bread and
meat, but he does tire of spices and sweet things, which
are not proper foods. Hunger, or the appetite, is a sign
when food is needed. Grown people get hungry about
every six hours, and children more often. When enough
food has been eaten there is a feeling that the hunger is
satisfied. If we should always heed these two signs, it
would be much better for us.
65. False appetites. — But we can teach the taste and
appetite so that they are no longer sure guides. After a
full dinner has been eaten, and when the appetite has been
satisfied with plain food, a dessert made of sweets, spices
and jellies is brought in. This at once makes a new appe-
tite, and man satisfies it for the sake of his pleasure. So
he does two wrong things to his body. First, he puts too
much food into his stomach ; second, he eats too much
sugar. The sugar overworks the liver, and he is very
liable to have a bilious attack. We need a little more
sugar than fat, but we often eat many times as much. A
natural appetite is satisfied with three meals a day, but the
false appetite leads us to eat cake, candy, and fruit at all
times. We seldom want to eat bread or meat between
meals. This shows that the cells of the body are not call-
ing for food. By eating at all hours we keep the stomach
at work without rest, and it soon tires itself out.
66. Too fast eating. — When we eat too fast, the food
cannot be chewed fine, but is swallowed in lumps. Then
the stomach must do the work which the mouth should do.
Besides, it does not have time to give notice that its wants
are filled, and so we eat too much. When we need to
wash food down with water, we are surely eating too fast,
but drinking at meals to satisfy a natural thirst is proper.
INTEMPERANCE AND POISONS
37
Our appetite sometimes leads us to drink very hot or
very cold water or tea. Although we cannot feel either
in the stomach, yet both disturb digestion.
One form of intemperance.
67. Intemperance. — Man is almost the only living being
that eats all kinds of food for the mere pleasure of eating.
Animals follow their natural appetites, and their stomachs
are healthy. Man eats to satisfy new appetites, and harms
his stomach so that it cannot digest even plain food. We
should be far better off if we never touched sweetmeats,
pie, and cake, but lived only upon bread and meat and
other plain foods.
Satisfying an appetite which does not indicate a need of
38 APPLIED PHYSIOLOGY
the body is intemperance. Almost everybody is intem-
perate in eating from the time he can walk, to old age.
Intemperance in eating is very liable to lead to intemper-
ance in drinking later in life.
Eating and drinking anything for mere pleasure is in-
temperance and harms the body. We may not see the
harm of eating a single apple in the middle of the fore-
noon when we are not hungry ; and yet this is an act of
intemperance, and, if repeated, tends to overwork the
stomach and to produce dyspepsia, and possibly a fever.
Eating some other things, such as green apples, nearly
always produces sickness, and we at once see that it is
a form of intemperance. But eating the first apple was
intemperance just as really as eating the green one.
A little pie or cake may be used in place of plain food,
but every one knows that eating much of it is intemper-
ance and produces sickness.
In some cases a great deal of intemperance does not
seem to do harm at once, and so men will risk being sick
for the sake of a moment's pleasure. They do not count
the cost when they are feeding an appetite.
68. Appetite for strong drink. — Using drinks which
contain alcohol is the worst form of intemperance. It is
such a bad form that, when we speak of intemperance we
usually mean the use of strong drink.
We can eat pie or cake or candy without being intem-
perate ; but any use of strong drink is intemperance, for it
is not needed at all by the body, but is used only for
pleasure. It does such harm that no one can drink much
without plainly showing its effects.
When we have been intemperate in eating pie or cake
we feel sick and could not eat more if we would. When a
person is harmed by strong drink the drink often makes
INTEMPERANCE AND POISONS 39
him feel well while he is slowly killing himself. This
power of strong drink to deceive a person into using it
while it is slowly harming him makes it the worst form of
intemperance. It affects every part of the body. These
effects will be described fully as we study the different
parts of the body.
69. Tobacco intemperance. — Next to using strong drink,
the use of tobacco is the most harmful form of intemper-
ance. It does not always do so much harm as strong drink,
for it usually acts so slowly that we do not notice its effects.
Like strong drink, it makes a person feel well while it
slowly poisons him. It often does great harm to different
parts of the body. These effects will be described as we
study each part.
70. Sickness. — When each cell of our body does its
work perfectly, and when all the cells work together, we
are well and healthy. When one set of cells is out of
order, it affects all the others, and we are sick. Thus, if
the cells of the stomach fail to digest food, all the cells
lack food, and so the stomach makes the whole body feel
sick. The doctor then comes to see what was out of order
first, and tries to correct its action so that we may be well
again.
v,/ 71. Drugs. — When a person is sick, the doctor often
gives him substances which are called drugs. They are
not food, and even if they were, they are in too small
amounts to furnish much nourishment. In the stomach
and intestine they are taken up with the food, and are
carried by the blood to the cells of the body. There they
cause the cells to act in' a more natural manner. When
the cells finally act as usual, we are well again. For in-
stance, in a bilious attack, the doctor gives a pill or powder,
which is taken up by the blood and carried to the liver.
40 APPLIED PHYSIOLOGY
There it causes the liver cells to act more strongly and to
produce more bile. In a short time, the liver is acting right
again, and we are well. In the same way, other drugs act
upon other parts of the body and make them act rightly
when they are out of order.
72. Poisons. — A little of a drug causes the cells of the
body to act in a more natural way. Too much of a drug
either causes them to overwork, or else stops their action,
in either case producing sickness. Substances which inter-
fere with the work of the the cells are poisons. So all
drugs and narcotics are poisons if taken in too great
amounts. For this reason, we should never use them un-
less we are guided by some one who understands their use.
73. Signs of poisoning. — When a person is poisoned,
he suddenly becomes very sick and weak. There is no
sickness that will come on so suddenly as that caused by
poisoning. The sufferer's mind will probably be affected,
and he will be much alarmed for himself.
74. How to help a poisoned person. — When a person is
poisoned, the first thing to do is to get rid of the poison
as soon as you can. This you will do by making the per-
son vomit. You can always do this at once by running
your finger down his throat as far as possible. Do not
get frightened, but at once either ask the person to do
it himself or to let you do it.
You will also help vomiting by having the person drink
as much water as possible. This will also wash out his
stomach and get rid of more of the poison.
You will also aid vomiting by giving a tablespoonful
of mustard mixed in water. The point is to get the per-
son to vomit as soon as possible. By remembering this,
you may be able to save a life.
A poisoned person will feel very weak after he has
INTEMPERANCE AND POISONS 4 1
vomited. So you must give him a stimulant. Some strong
coffee will be the best of all. You will do him no harm
by giving it.
Finally, keep the person quiet, for in his weakness he
cannot stand much exertion in moving about.
75. Spoiled food or poisonous food, such as some varie-
ties of mushrooms, causes great pain in the lower part of
the body, and great weakness. When this comes on, vomit-
ing should be induced at once. Often the stomach will
vomit the food of its own accord, and so nature cures the
poisoning. When a person vomits, it usually means that
some poison is upon the stomach.
76. Opium poisoning. — The most common form of poi-
soning is that by opium. Opium is the dried juice of the
poppy plant. It is used to produce sleep and to relieve
pain, and is a strong poison. A piece as large as a grain
of corn could put a man into a deep sleep, and three or
four such pieces might kill him.
People often keep different kinds of opium in the house.
Laudanum is opium dissolved in nine times its weight of
alcohol. Paregoric is a weaker form of opium and alcohol.
Most soothing syrups which are used to quiet children, act
by means of their opium. They can easily poison a baby.
Morphine is a powder made from opium, and is ten times
as strong as opium itself.
You can tell opium poisoning by the deep sleep which it
produces. A poisoned person should be made to vomit,
and afterward he should drink some strong coffee. You
should also keep him awake by making him walk or even
by striking him with a whip ; but do not bruise his skin.
77. Carbolic acid poisoning. — Carbolic acid is often kept
in houses for use as a wash during sickness. If it is swal-
lowed it will burn the throat and stomach, leaving a white
42 APPLIED PHYSIOLOGY
scar. The person will feel very sick and may faint away
and become insensible. You should give him milk or raw
eggs. Then give Epsom salts, which will tend to stop the
action of the poison. Carbolic acid, when used as a strong
wash, may injure the skin, and cause sickness as if it had
been swallowed. Treat the person as if he had swallowed
the poison.
78. Arsenic. — Paris green, London purple, and most
other rat and insect poisons are forms of arsenic. When
swallowed they produce vomiting and great pains in the
stomach. A very little of the poison will cause death.
Give the poisoned person milk and raw eggs.
79. Insect stings. — Bees, hornets, spiders, mosquitoes,
and other insects sometimes inject a little poison beneath
the skin when they bite or sting. This produces a swelling
and great pain as though something were burning the skin.
If a number of stings are made there may be enough poison
to make a person very sick.
The pain of bites and stings can be relieved by applying
a lump of cold mud at once. Some carbolic acid water,
lime water, ammonia, or camphor will also help.
80. Snake bites. — In the United States there are but
few kinds of snakes that bite, and still fewer whose bites
are poisonous. A snake bite is like that of a very large
and poisonous insect. The bitten part swells and becomes
very painful, and the person feels weak all over.
You should tie a handkerchief above the bite as soon as
possible, so as to keep the poison from going through the
whole body. Then suck the bite so as to take out the
poison, being careful to spit out the blood and poisons
You should cut open the bitten part so as to let the blood
flow and wash away the poison. You should also give
strong coffee or other stimulant.
INTEMPERANCE AND POISONS 43
jj* SUMMARY
1. The taste and the appetite are two sure signs of when
and how much food to eat.
2. Man spoils these signs by eating sweet and spicy foods
at all hours for the sake of the pleasure of eating,
and by eating too fast.
3. Eating for the pleasure of eating when the body does
not need food is as real intemperance as taking
strong drink.
4. Sickness is due to the imperfect or stopped action of
some of the cells of the body. Drugs are then given
to cause the cells to act rightly again.
5. Too much of any drug hinders the action of the cells,
and so is a poison.
6. When a person is poisoned, cause him to vomit by put-
ting the finger down the throat, or by giving him
large drinks of water, or by giving him mustard and
water.
7. Also give a poisoned person strong coffee.
CHAPTER V
TOBACCO
81. Narcotics. — Besides eating his natural food, man
often forms a habit of eating things which harm him, and
yet he uses them because he learns to enjoy their taste or
the feelings which they produce. Most of these things
belong to a class called narcotics ; they benumb pain and
weaken both the brain and the body. At first, both these
substances themselves and also the feelings which they
produce are unpleasant. Men learn to like their benumb-
ing effects, and soon get into the habit of their use because
they take away pain and calm a person when he is nervous
or worried. The most commonly used narcotic is tobacco.
82. Tobacco. — Tobacco is the leaf of a tall plant. It
requires a richer soil and more care than any other crop.
Soil which raises tobacco is kept from raising a great
quantity of real food. A few crops of tobacco take so
much richness from the soil that only small crops of any-
thing else will grow afterwards.
The leaves of tobacco contain a narcotic poison called
nicotine. Nicotine gives the tobacco most of its smell and
taste, and if it is taken out, the tobacco is spoiled. It is
easily turned into a vapor, and is found in the smoke when
tobacco is burned. It is so poisonous that the smoke of
two or three pipefuls of tobacco contains enough to kill a'
man if it should stay in his body. A single drop of it can
kill a strong person. Tobacco is sometimes made into a
44
TOBACCO
45
poultice and put upon a sore. The nicotine from the poul-
tice has been known to poison the body, and even to pro-
duce death. The nicotine of a few puffs of smoke makes
a person very weak and sick when he begins to smoke.
This shows how poisonous it is. After a person has
smoked a few times he becomes used to the poison so that
he can smoke or chew a great deal without becoming sick,
but a larger amount than usual sickens even an old smoker.
83. Why tobacco is used. — Persons make many excuses
for using tobacco. One says it is company for him.
Another says it makes his head clear so that he can think
better. Some smoke because others do, and boys smoke
because they think it makes them look like grown men.
Some say that they smoke to help digest the food, and
some that they use tobacco so that their stomachs will not
need so much food. Some smoke to cure a cold in the
head. Some boys learn to chew by putting tobacco in a
decayed tooth, thinking it will stop toothache. It is easy
to find an excuse for using tobacco, but where so many
excuses are given, none are good.
84. Why tobacco should not be used. — There are many
reasons why a person should not use tobacco in any form.
It always leaves an unpleasant odor about the clothes and
room, and upon the breath. A person who cares for the
feelings of others will not make himself disagreeable with
the smoke of tobacco.
Chewing and smoking make more saliva flow than the
mouth can take care of. The spitting which this causes
ought to keep any one from using tobacco. Tobacco does
not help digestion, but those who use it are very apt to
have a coated tongue and headache, showing that their
food is not digested as it should be. Many also have a
sore throat and a cough and a husky voice as the direct
46 APPLIED PHYSIOLOGY
result of using tobacco. The worst effects are that it
sometimes causes weakness of the heart and poor sight, or
even blindness. These effects will be studied later.
All these bad effects can be produced in those who
breathe the smoke in a room. Babies can easily be made
sick by tobacco smoke in a room with them. The young
are far more easily poisoned by tobacco than older per-
sons. In the young the weakness caused by tobacco is
often so great as to hinder the growth of the body. Boys
who wish to grow to be large men had better not use
tobacco. In a crowd of boys it is often possible to pick
out those who smoke by their smaller size, the thinness of
their flesh, and their pale, pasty complexion.
85. Smoking. — Tobacco is used either by smoking,
chewing, or as snuff. All tobacco smoke is poisonous, but
the stronger the tobacco, the more poisonous it is. The
burning also makes poisonous gases, one of which is a
dangerous gas like that used in lighting houses. The
poisons stay in the stem of a pipe which has been smoked
for some time until so much collects that it makes even an
old smoker sick. The smoke of a pipe contains more
poisons than the smoke of a cigar, for the cigar is more
completely burned up.
86. Cigarettes. — Cigarettes are made from mild tobacco
and contain less nicotine, yet the danger from using them
is still greater, for the smoke is easily drawn deeply into
the mouth and often into the lungs, and so more of the
poison is apt to reach the cells of the body.
87. Chewing. — Chewing tobacco is a dirty habit which
has no excuse beyond the pleasure men learn to take in it.
No man who prides himself upon the good looks of his
teeth and lips will chew tobacco. It is the most poisonous
of all the forms in which tobacco can be used.
TOBACCO 47
88. Snuff. — Taking snuff is going out of fashion.
Snuff is used to produce a sneeze. It may be fun to
make oneself sneeze, but snuff is poisonous and is a bad
thing to use for this purpose. A sneeze is really an at-
tempt to drive out something which is hurting the nose.
Surely it does not pay to hurt the nose for a sneeze.
We all know of men, and even women, who chew and
smoke every day and yet live long and healthy lives.
If tobacco evidently harmed every one who uses it, the
law would have stopped its use long ago. But because
its hurtfulness shows itself only slowly and because the
body can become somewhat used to it, men say it is harm-
less, and some even say it is good for the body. The truth
is that tobacco will surely do a great harm to at least one
quarter of those who use it, and may harm the others at
any time.
89. Opium. — Opium is another narcotic which men
learn to use. It is the dried juice of the poppy plant. It
stops pain, produces sleep, and gives nervous people a
calm and contented feeling. Many different substances
in the opium can do this, but a white substance called
morphine is the main one. In large doses, opium or mor-
phine causes deep sleep and great weakness of the body
until death occurs. In small doses it hinders the work of
the stomach and intestine, so that food is not digested as
it should be. So the body loses weight and strength.
The body may get used to the drug so that more and more
is needed to quiet the nerves. It always weakens the
body and causes death in a few months or years. The
opium habit is one of the hardest to break. Some use
opium by smoking it like tobacco.
90. Chloral. — Chloral is a solid with a sharp, peppery
taste. It is used much like opium. It calms nervousness
48 APPLIED PHYSIOLOGY
and causes sleep, but it poisons the body and produces
death even more quickly than opium.
91. Narcotic poisoning. — Poisoning by opium and such
drugs produces sleep. So the poisoned person must be
kept awake. One must shake or pinch him, or, in fact, do
almost anything to arouse him, for if he gets sound asleep
he is liable to die.
SUMMARY
i. Men use narcotics to benumb pain and to dull the brain
so that it does not worry.
2. Tobacco is a narcotic which depends upon a poison
called nicotine for its effects.
3. Tobacco is smoked, chewed, and snuffed up the nose.
In all three ways, nicotine enters the body.
4. Tobacco not only harms those who use it, but its use is
unpleasant to those who do not use it.
5. Opium is a narcotic used to produce sleep and to quiet
pain. Its use always does great harm, and if con-
tinued produces death.
6. Chloral is used like opium, and is even more deadly.
7. A person must be kept awake when he is poisoned by
a narcotic.
CHAPTER VI
ALCOHOL
92. Yeast. — A narcotic which man often takes into his
body is alcohol. When a little sugar in water stands a
while, bubbles of carbonic acid gas rise up through the
water, and the liquid turns sour. If one puts more sugar
in the water, the bubbles will rise,
but the liquid has a strong odor and
a sharp taste, for some of the sugar
has turned to alcohol. We say that
the sugar ferments. When there is a
great deal of sugar in the water, it
does not ferment at all. Let us seek
the causes of these changes.
In the air there float tiny germs of
a living plant called the yeast plant.
When these germs fall into sugar and
water they grow, and produce great
numbers of yeast plants. Each yeast
plant is only a single round or oval
cell, so small that a microscope is needed to see it. By its
growth it changes the sugar to alcohol by taking some car-
bonic acid gas away. But if there is a great deal of sugar
in the water, the germs will not grow at all. This is why
fruit preserved with a great deal of sugar keeps so well.
93. Souring. — If there is only a little sugar in water, a
smaller germ from the air grows with the yeast. This
Yeast plant cells ( x 500)
OV. PHYSIOL. (INTER.) — 4
49
50
APPLIED PHYSIOLOGY
changes the alcohol to vinegar, which makes the liquid
sour. Changing sugar to alcohol or vinegar is fermeiita-
tion. All strong drink contains alcohol, and is made by
the fermentation of sugar. Alcohol is sugar with some of
its carbonic acid gas taken away.
94. Alcohol. — Alcohol is a colorless liquid which burns
very easily, with little flame and no smoke, but with a
great deal of heat. It has a sharp,
sweetish taste and smell. It turns
to vapor very easily. It takes water
away from substances, and causes
them to shrivel up. It hardens
albumin, just as heat hardens the
white of an egg. Because it hard-
ens substances and takes away their
water, it is used to keep things from
decaying. It is used for dissolving
many things which water would
not affect ; and from it ether,
chloroform, and numberless other
useful things are made. It is a very valuable article, and
manufacturers and chemists could not do without it. But
man has learned that its taste gives him pleasure, and
that the feelings which result are often very pleasant.
So day after day men drink liquors containing it for the
mere pleasure of drinking.
95. Why men drink. — Men are ashamed to waste their
money and strength in mere pleasure, and so they make
excuses for using the strong drink. One man says that it
warms him, and another that it cools him, and another that
it makes him forget his cares while he remembers only
pleasant things. One takes it to keep himself awake, and
another to make himself sleep. . Some take it to cure a
Fermentation in a jar of
cherries.
ALCOHOL 5 1
pain or a cold, and many drink because others do. The
real reason for drinking alcohol is that men like the feel-
ings which it produces better than they like healthy minds
and bodies. Because strong drink can be sold for a great
deal more money than it costs, selling it is a very profitable
business, and men fit up costly rooms so as to entice men
to buy it.
96. Effect of alcohol upon the mouth. — Alcohol is a
poison which has definite effects. It usually has effects
opposite to those that men think it has. As it is swal-
lowed, the alcohol in all drinks injures the cells of the sur-
face of the mouth and leaves a false feeling of thirst.
So a second drink is taken to relieve the thirst caused by
the first. Thus the drinker keeps on drinking, and all the
while grows more thirsty, even though his body has suffi-
cient water. His mouth gives off unpleasant odors, but
this is due in part, at least, to the coated tongue and sick
stomach which drink causes.
-4)97. Effects of alcohol upon the stomach. — In the stomach,
the alcohol of strong drink hinders or stops the action of
the gastric juice. So food may digest more slowly or pass
into the intestine without being changed. The alcohol
also hurts the mucous membrane of the stomach. Then
this may become red and pour out a slimy mucus. The
alcohol often causes a person to vomit. This is really a
good thing, for so the stomach gets rid of the poison.
98. Protection against alcohol. — When strong alcohol
is taken into the mouth, the saliva flows freely and dilutes
it so that it is no longer capable of burning the mucous
membrane. This flow of saliva is like the flow of tears to
wash away a speck of dirt from the eye.
When alcohol reaches the stomach, the glands in its
mucous membrane pour out gastric juice and mucus to
52 APPLIED PHYSIOLOGY
dilute it just as the mouth poured out saliva. If it were
not for this protection, a drink of strong liquor would
quickly destroy the stomach. Our bodies can stand a
great deal of abuse, because nature has provided us with
protection against all ordinary abuse. Still, after a time,
the drinking of alcohol and all other abuses are certain to
do great harm.
99. Digestion of alcohol. — Alcohol itself needs little or
no digestion. After it has been much diluted by the fluids
in the stomach and intestine, it soaks into the blood tubes
along with the food of the body. There it is washed away
in the rapid blood stream, so that not enough collects at
one time to damage the blood directly. It is carried to the
liver and there disappears at once. Little or none can
ever be found in the body beyond the liver. It is probably
oxidized like sugar, only very much more rapidly.
100. Poisons produced by alcohol. — Destroying or oxi-
dizing alcohol uses oxygen, so that there will be too little
left for the body and its food. When a stove gets too
little oxygen through its draft, it produces poisonous smoke.
If the albumin, sugar, and fat of the food get too little
oxygen, they, too, give rise to foul substances. These new
products go through the whole body with the blood, and
produce far more poisonous effects than alcohol itself.
Even after alcohol is destroyed, its harm continues as great
as ever.
Trying to use alcohol as a drink is like trying to burn
kerosene in a coal stove. By using great care a little
kerosene can be burned without doing much harm, but it
smokes and smells bad and cannot be controlled. Alcohol
behaves like the kerosene. It gives rise to poisonous sub-
stances, and may overcome the body at any time.
101. How alcohol weakens the cells. — When alcohol is
ALCOHOL 53
used, the cells are weakened and poisoned both by the
alcohol and by the half-burned albumin, sugar, and fat.
Then they fail in their attempts to do their work. So
walking is done in a staggering way, and the voice is thick
and uncertain. A man in this condition is said to be drunk.
The alcohol may make him still weaker, so that he cannot
stir, but lies dead drunk, or he may even be killed by the
alcohol. At first we might think that the destruction and
oxidation of alcohol would develop heat and force which
the body could use. But it must be remembered that the
cells themselves are made weak, both by their lack of oxy-
gen and also by the poisons of the half-burned albumin
and fat. If an engine is weak and rusty, a hot fire under
the boiler will not make it do more work, but it may cause
the whole machine to be blown up. A few men seem
able to drink for years, and yet remain in fair health. A
little alcohol will do great harm to most men. At any
rate, drinking will not help men in their work or help
them to live better lives.
102. Effects of alcohol upon the liver. — The liver itself
suffers from the alcohol. It has to take care of the heat
and of the half-burned albumin, fat, and sugar, and of all
the poisons which are produced. So it is over-worked and
often fails in its duty. Thus, a drinker is very apt to
have bilious attacks. If drinking is kept up for some
time, the liver often wastes away, and becomes hard and
rough and unable to do its work. Physicians long ago
called such a liver a " gin drinker's " liver. When the
liver has been harmed in that way by alcohol, the body
slowly wastes away, and finally death occurs as much by
starvation as by poison. Because alcohol disturbs both
the preparation of the food of the cells and also its oxida-
tion, it affects every cell in the body. These effects will
54 APPLIED PHYSIOLOGY
be told when the work of each separate set of cells is
studied.
103. Habit of drinking. — While alcohol is harming a
man, it makes him feel good, so that he does not think of his
danger. At first he drinks only a little, but it seems to make
him feel good. After it has gone out of his body, he feels
its harmful effects. Then he wants another drink, so as
to make himself feel well again. This desire to take alco-
hol may compel a man to drink, even when he knows that
it is harming him. Strong drink is like a man who visits
at another man's house, but is all the time robbing him.
104. Laws against selling alcohol. — If alcohol harmed
only the body of the person who uses it, it might not con-
cern any one except the drinker himself. But it does
other things beside which the effects upon the body are
of less account. It takes away a person's mind and char-
acter so that a truthful and honest man becomes untruthful
and cannot be trusted. He is thus very apt to injure
others, and even his dearest friends. Every day we read
of drunken husbands beating their wives and children.
Many a criminal has had to get half drunk before he has
dared to commit his crime. Thus many have to suffer
because one man wants to have the pleasure of drinking.
Strong drink harms not only the drinker, but also his
friends and neighbors. So it is right to make laws which
shall keep a man from selling alcohol and strong drink.
School children are now learning how bad alcohol is, and
when they grow up they will know better than to use it.
105. Form of alcohol in drinks. — The effects of alcohol
are the same in whatever form it is taken. Pure alcohol
has an unpleasant taste and burns the mouth of even an
old drinker. So in drinks it is always mixed with water.
106. Wine. — We have seen how the yeast plant causes
ALCOHOL
55
sugar and water to ferment to alcohol. Fruit juice con-
tains sugar dissolved in the water of the juice. The
simplest way in which an alcoholic drink is made is to
squeeze the juice from the fruit and let it ferment in open
bottles or barrels. There are always enough
germs of the yeast plant upon the outside
of the fruit to start the fermentation, and
in a few weeks or months the sugar of
the juice has turned to alcohol. The
strongest liquor made in this way can be
only one eighth alcohol, for more than that
kills the yeast plant. When grape or cherry What wine
or blackberry juice is used, the liquor is
called wine ; but if apple juice is used, it is called cider.
It all contains alcohol. Cider begins to ferment in a
few hours after it is made, and in a week it often has
enough alcohol to make a person drunk. In a short
time other germs enter the cider and change the alcohol
to vinegar. Homemade wine contains alcohol, and its
use is as harmful as though it were bought at the saloon.
Some wine has pure alcohol added to it to make it keep
better.
Since wine is made of fruit juice, it may contain some
albumin, which is of value as food, but to buy wine is a
very expensive way to buy albumin, and besides the albu-
min of wine is not nearly so good as the albumin of bread
or meat. Wine may contain some unfermented sugar also.
The flavor of wine depends upon the kind of fruit and
the amount of fermentation. It has little to do with the
amount of alcohol in the wine. Fermented fruit juice
was the only kind of alcoholic drink which people knew
in ancient times. It was weak in alcohol, and a great deal
was needed to make a man drunk. Much of the wine
56
APPLIED PHYSIOLOGY
which we read about in the Bible was fresh grape juice
used L.efore fermentation had begun.
107. Beer. — The alcoholic drink which is most used is
beer. Beer is made chiefly from barley. The grain is
moistened, and each seed begins to grow. This turns the
starch of the grain to sugar. When the sprouts are about
half an inch in length, the grain is dried.
This dried grain is called malt. The malt is
boiled in water so as to dissolve the sugar.
The liquor is strained off, and hops and other
flavoring matters are put in. Then yeast
is added, for the boiling kills the yeast
which was there at first. Fermentation
takes place and changes the sugar to alco-
hol. Beer is about one twentieth alcohol,
but some is a great deal stronger. Beer, like wine, con-
tains some albumin, but the best beer or ale has little of
the food part of the grain of which it is made. Some
men drink three or four quarts of beer a day. This
makes them fat, but it does not give them strength.
Root beer is made at home by boiling aromatic roots and
leaves with molasses and adding yeast to the liquor. The
molasses ferments and becomes alcohol. All
root beer has alcohol in it.
108. Distilled liquors. — When a pot of
alcohol and a pot of water are set upon a
stove together, the alcohol begins, to boil
much sooner than the water, and is sooner
turned to vapor. If water and alcohol are
What whisky mixecj together and heated, the alcohol makes
contains. ° .
the largest part of the vapor, and is at last
driven off before half the water is gone. If this vapor
is collected and cooled, it becomes a liquid, and con-
ALCOHOL 57
tains far more alcohol than the first liquor. If this
liquor is boiled over and over again, the alcohol is fur-
ther separated from the water until it is almost pure.
Separating alcohol from water by heating is called distilla-
tion. Many liquors are made by distillation. If wine is
distilled, the liquor is called brandy, but if grain is used to
make the alcohol, it is called whisky. Brandy and whisky
are each about one half alcohol. When first made they
contain a very poisonous kind of alcohol. They are both
kept for months, and even years, before being used, so as
to change this more poisonous alcohol to common alcohol.
109. History of strong drink. — The germs of yeast grow
almost everywhere. By their growth alcohol is always
formed wherever fruit decays or its juice has an oppor-
tunity to collect. For thousands of years men have known
the taste and the effects of fermented liquors, and how to
produce the fermentation. Almost every known race of
men has made wine from the earliest times. Noah made
wine shortly after the flood, and wine is mentioned in
many places in the Bible. In the earliest recorded times
people of Egypt and of Assyria used wine on their tables
and often made themselves drunk. The native Mexicans
had an intoxicating liquor when the Spaniards came in the
early part of the sixteenth century. But the ancients never
used drink so strong as it is made now, for fermentation
stops when the juice becomes one eighth alcohol.
About eight hundred years ago the professors in the
colleges and all other learned men of the time were look-
ing for three impossible things. They were trying to find
out by the stars what would take place in times to come.
This study led to our knowledge of astronomy.
They we're trying to discover how to change common
metals to gold. By their mixing and dissolving all kinds
58 APPLIED PHYSIOLOGY
of substances they built up the beginning of chemistry,
and discovered many things about wine and spirits.
Above all things, men of eight hundred years ago were
seekers for a substance which would make the old young
again and prevent the young from growing old. They
believed that there was really such a substance existing in
the form of a very light spirit or gas. So they boiled sub-
stances in order to collect their gases. When wine was
boiled they obtained a new substance which we know as
alcohol.
A famous Arabian, named Albucasis, drank some of the
alcoholic liquor which he had made and which was really
brandy. He at once seemed to be a young and joyful
man again. He told of his wonderful discovery, and by
means of his so-called "water of life," he brought back the
joys of youth to other old men. They soon discovered
their mistake, but found themselves enslaved by the habit
of taking the poisonous liquor. Soon all, including Albu-
casis himself, died from the effects of the strong drink.
Before their time men had become drunk and had died
from the effects of wine; but the effects of the distilled
liquor were far more rapid and deadly than anything which
they had known before. To-day men drink as much
brandy and whisky as they do wine.
Within the last few years men have found out how to
make strong drink quickly and cheaply. To do this, how-
ever, they must either add poisons or else neglect to
remove some which are always found in new liquor. Yet
no one can tell the poor liquor from that which is old and
pure. Any strong drink is poisonous ; but much of the
cheap liquor to-day is as much more dangerous than the
whisky of fifty years ago as that was more poisonous
than the wine of old.
ALCOHOL 59
SUMMARY
1. Alcohol is made from sugar by the growth of the yeast
plant. In the body it needs no digestion, but it hin-
ders the digestion of other things. It enters the
blood at once, but quickly disappears again.
2. The use of alcohol tends to make men drink even when
they feel that it will harm them.
3. Its oxidation uses up oxygen, so that too little is left
for the albumin, sugar, and fat. Half-burned and
poisonous substances are produced by their oxidation
like the gases from a smoking lamp.
4. These poisons and the lack of oxidation in the cells of
the body weaken the cells.
5. Alcohol makes the liver smaller and harder.
6. The three different kinds of alcoholic drinks are wine,
beer, and distilled liquors.
7. All fermented drinks contain alcohol, and so are forms
of strong drink.
CHAPTER VII
THE BLOOD AND ITS CIRCULATION
110. The blood. — After the food has been digested in
the stomach and intestine and made into blood in the
liver, it is sent to feed each cell of the body. About one
thirteenth of a man's body is blood. This makes between
five and six quarts.
The blood is a red liquid, but under a microscope it
looks like clear water in which there float a great many
round bodies. Most of these bodies
are red, and are called red blood cells
or corpuscles ; a few are white, and are
c[Jo (g)® called white blood cells or corpuscles.
Blood corpuscles m The blood ceUs< _ Each red blood
(x 400).
■1 f a ut a cell is a round, flat plate. It does not
a a pile of red blood ' ^
ceils. feed the cells of the body, but supplies
b refla^w°sdeCellSSeen them with oxygen from the air in the
c red blood cells seen lungs. The red cells form nearly one
d wheuegebTood cells. half of the blood.
Each white blood cell is round like a
ball. It moves with the blood, but it can move all by
itself and live outside the blood. It is almost a living
being in the blood, separate from the body. The white
blood cells are only one three-hundredth as numerous as
the red cells. They are always looking for weak or in-
jured parts of the body, and when they find such a spot
they leave the blood tubes and gather around it to mend
60
THE BLOOD AND ITS CIRCULATION
6l
it. They also surround and destroy poisons which happen
to get among the cells. We will speak of this later when
we talk of inflammation and of catching cold. (See § 137.)
112. Plasma. — The liquid part of the blood is called
plasma. It is -water, in which a little albumin and mineral
matters are dissolved. The albumin and the mineral mat-
ters are the real food of the cells.
When blood is drawn from the body, it soon becomes
like jelly, or it clots, as we say. In clotting, some of the
albumin of the plasma
becomes hard like a boiled
egg and makes the whole
blood like jelly. Soon
the clot begins to grow
smaller and to squeeze
out the liquid parts of
the blood. Then the
clot will float in a straw-
colored liquid called
serum. In a cut a clot
reaches into the mouth
of each blood tube and
stops the opening, so
that no more blood can
ing is stopped.
113. Arteries. — The blood is carried to the cells of the
body through tubes which branch and divide again and
again, until they reach every part of the body. The tubes
which carry blood to the cells of the body are called
arteries. Their sides are strong and tight, so that they
cannot burst or leak. In them are muscles which can
make them larger or smaller, so as to let the right amount
of blood pass through for the use of the cells of the body.
Arrangement of capillaries.
a smallest artery.
b smallest vein.
c network of capillaries.
flow. This is the way all bleed-
62
APPLIED PHYSIOLOGY
114. Capillaries. — The end of each artery divides into a
number of fine tubes called capillaries. The capillaries
make a network so fine that they touch every cell of the
body. The point of a needle cannot prick the skin with-
out bursting some of the capillaries and so drawing blood.
Each capillary has sides so thin and soft that the liquid
parts of the blood easily
soak through to reach the*
cells, and even the white
blood cells burrow through
its sides without harming
the tube. The capillaries
are only just large enough
to let the blood cells
pass through.
115; How to see the
capillary circulation. —
The web of a frog's foot
is very thin and clear, and yet contains many capillaries.
If it is spread out under a microscope, you can see
the blood as it shoots through the tiny tubes. You can-
not see the liquid part, for it is like water, but you will
see the red blood cells, which, in the frog, are egg-shaped.
They will pass through the larger tubes in a stream too
rapidly for you to see the separate cells. In the smallest
tubes, a cell may get stuck crosswise for a moment and
stop up the whole tube, but it soon becomes free again
and passes on. Sometimes a cell starts to go through,
when a little movement of the leg will press it back again.
You should get your teacher or some physician to show
you this circulation. This will help you to remember
that millions of these tiny streams are continually flowing
through every part of your body.
diagram showing how food reaches the
cells from the capillaries.
THE BLOOD AND ITS CIRCULATION
63
116. Veins. — The capillaries come together again and
form tubes called veins. Each vein is a tube much like
an artery. It carries blood away from the cells. It has
valves which permit blood to flow toward the heart but
keep it from flowing back to the cells. Each vein runs by
the side of the artery which brought the blood to it. So
the blood tubes are like
a net hanging from two
ropes. One rope is an
artery, the net is the
capillaries, and the other
rope is the vein. The
blood is always moving
in the tubes. We must
find out what moves it.
117. The heart. — If
we follow the arteries
back, we shall see that
they unite and grow larger
until we reach a single
tube nearly an inch
through
called the aorta. At the d ventricle
beginning of the aorta is
a pump called the heart.
The heart lies just to the
left of the middle of the body, and just below the level
of the armpits. It is a bag about the size of the fist.
Its inside is divided so as to make two bags. Each bag
is a complete pump. The lower part of each side of the
heart is called a ventricle, and the upper part an auricle.
There are two openings in each ventricle. A hole in
its upper part leads to the auricle. It can be closed
Diagram of the heart while it is beating.
a vein entering the auricle.
b auricle.
This artery is c closed valve to keeP blood fr°m flowing
back into the auricle.
e artery.
f valve to keep blood from returning to the
ventricle.
64 APPLIED PHYSIOLOGY
tightly by two curtains. A hole in its side opens into an
artery.
When the ventricle is full of blood, all at once it becomes
smaller and squeezes the blood. The pressure closes the
opening to the auricle and keeps the blood from going out
that way, and so it passes into the artery. Three little
curtains keep it from running back into the ventricles.
The heart keeps the arteries full of blood, and presses
it through their branches and through the capillaries and
veins. It finally reaches the heart again and flows into
the auricles. Then it flows into the ventricles again, ready
for another round of the body.
The sides of the auricles are thin, for they are made
only to hold the returning blood while the ventricles are
squeezing blood into the arteries.
118. Why the heart is double. — The left part of the
heart sends blood to all parts of the body to nourish its
cells. The right half of the heart sends the blood only
to the lungs. There the blood gets air, which it carries to
the cells. Food is gathered from the intestine by blood
which is pumped by the left half of the heart, but in man
only the right half of the heart sends blood to get air.
A fish has only one auricle and one ventricle, which send
blood to get both air and food.
119. Course of the circulation. — The left half of the heart
sends blood through the arteries to all parts of the body.
They empty it into the capillaries. Here some of the
plasma and air go out to feed the cells. The rest of
the blood then enters the veins, which bring it back to the
heart, where it enters the right auricle and ventricle.
They send it to the lungs to get air. Then it returns to
the left auricle and ventricle ready for another round of
the body. It takes twenty seconds to send a drop of
THE BLOOD AND ITS CIRCULATION
65
blood through the left ventricle, then through the arteries,
capillaries and veins, and then to the lungs and back to
the left ventricle.
?^h^lor
All the blood in
the body passes
through the heart
every two min-
utes.
120. Venous
and arterial blood.
— In the lungs
the blood from
the veins be-
comes of a
brighter red
color. It goes
back to the heart
and is sent out
again by the ar-
teries. The blood
going to the cells
of the body is of
a bright red color
and is called ar-
terial blood. The
blood as it comes
from the cells is
darker in color
and is called ve-
nous blood. Ve-
nous blood is not
bad blood, but the change is due merely to the decrease
in the amount of air in the blood.
Diagram of the course of the blood in the circulation.
PHYSIOL. (INTER.) — 5
66 APPLIED PHYSIOLOGY
121. The heart beats and pulse. — While the heart is
squeezing the blood, it can be felt through the sides of the
body ; this is called a heart beat. Each heart beat makes
a wave of blood in the artery which can be felt when the
artery is near the skin. This wave is called a pulse and is
best felt in the wrist. The heart beats about seventy-five
times each minute. Running or other work of any kind
makes it beat faster, so as to send more blood to the cells
which are working.
122. How cells eat. — Let us learn exactly how the cells
of the body eat. We have seen how albumin and mineral
matters soak through the sides of the capillaries along
with the liquid parts of the blood, so as to reach the cells
of the body. Each cell is thus bathed in food, and eats
by soaking it in from all sides. So each cell is like the
ameba, but with these differences :
First. The ameba must seek, catch, and digest its
food, while the cells of the body are always soaked in food
ready for their instant use. A few cells of the body in
the stomach, the liver, the heart, and the blood tubes do all
the work of making the food ready for the rest of the cells.
Secondly. The ameba can move about, while the only
cells of the body which can move about are the white
blood cells. The rest are held in place by little strings
called connective tissue.
Thirdly. The ameba does just what it wants to, while
the cells of the body each have one kind of work to do
and must obey the orders of the mind in doing it.
Besides eating, each cell takes air from the blood and
gives off carbonic acid gas and water and other waste
matter from every side. Thus each cell breathes. We
shall see how it breathes when we study the lungs.
123. The lymph. — The cells cannot eat all the plasma
THE BLOOD AND ITS CIRCULATION 6y
which soaks through the capillaries, and so some always
surrounds the cells. White blood cells also go through the
sides of the capillaries and live between the cells of the
body. Each cell also gives off waste matter. The mix-
ture of these matters makes a fluid called lymph, which is
always bathing the cells. Lymph is thin blood without
its red cells. Only a little lymph can go back to the
capillaries ; so to take away the rest there is another set
of tubes called lymphatics.
124. Lymphatics. — Each lymphatic is like a small capil-
lary with thin walls. It begins in spaces between the
cells and carries away the lymph, just as a pump driven
deep into the wet earth brings up water. The smaller
lymphatics unite to form about twenty fine tubes for each
limb. They are too small and thin to be easily seen.
They run up the limb, and at the backbone join together
to form a single tube about the size of a quill. This tube
is called the thoracic duct. It opens into a large vein in
the neck. Thus the matters which leak out of the capil-
laries return to the blood in a roundabout way. Digested
fat also reaches the blood through the lymphatics. The
lymphatics are really a third set of blood tubes.
125. Lymph nodes. — Here and there the lymphatics
pass through little bodies like grains of wheat or corn.
They can be felt under the lower jaw and in the groin,
and are called lymph nodes. Each node is like a sponge
filled with white blood cells. As the lymph flows through
the nodes they strain out and keep back poisons and waste
matters which the white blood cells eat and destroy. So
these nodes protect the body against poisoning. In some
diseases they get so full of poison that they become
swollen, red, and painful. In scrofula the nodes in the
neck often form large swellings from this cause.
68 APPLIED PHYSIOLOGY
126. Regulation of the flow of blood. — When a cell is
working hard, it needs more food than when it is still.
Nature provides more food for a working part in two ways :
First. The muscles in the arteries relax, so that the
tubes become larger. Then more blood flows through the
part. When you run, your face looks red from this cause.
Second. The heart itself beats faster and with greater
strength. After a race you can feel your heart beat
within your chest. In these two ways nature always pro-
vides the exact amount of food which each part needs.
127. Effects of too much exercise. — During severe work
the heart works harder, so as to provide food for the
cells. This soon wears out the heart, so that it cannot
send enough blood even for light work. Boys can run or
work as hard as they please for a minute or two at a time
and will not be harmed. But they often try to see which
one can run the farthest or lift the most. Then they may
get very tired and may so weaken their hearts that they
never recover.
128. Fainting. — When the heart beats with little force,
or stops beating, the cells suffer at once. The brain suf-
fers sooner than any other part. Then the mind stops
acting, and the person is faint. His face is white, for it
has no blood, and he is in a deep sleep.
When a person faints, lay him down with his head low,
so that blood will go to the brain. Rub his arms and legs
towards his body to drive the blood to his heart. Also
throw cold water on his face to cause the heart to beat
harder. In a moment or two he will revive and be as well
as before.
129. Alcohol and blood. — Alcohol hinders the digestion
of food and weakens the liver so that it cannot change
the food to blood as it should. Thus the blood carries too
THE BLOOD AND ITS CIRCULATION 69
little food to the cells. Men who drink become thin and
weak. But beer drinkers take a great amount of water
in the beer, and this makes them heavy and large. They
look fat and healthy, but there is little strength in their
flesh.
When alcohol takes oxygen from the body, the real food
is half burned. The poisons which are produced remain
in the blood and are carried to the cells and still further
weaken them. So the drinking man can be injured by
causes which would have no effect upon him if he did not
drink. It is not true that alcohol helps any one to resist
disease ; the truth is that the drinker is very liable to be-
come sick.
t 130. Alcohol and the arteries. — The oxidation of alcohol
makes a large amount of heat suddenly. To get rid of
it the muscles of the arteries suddenly loosen and let the
tubes become larger. So more blood flows through to the
capillaries. This happens in the skin more than anywhere
else, and so more blood touches the air and the heat is
lost. When the arteries have often been made larger,
their muscles lose the power of acting, and so they remain
too large permanently. After a while a drinker's face and
nose are red all the time. If his flesh is cut, an extra
amount of blood is needed to heal the cut; when the
arteries cannot regulate the amount of blood, the cut
heals slowly. If any part of the body is diseased, the
extra quantity of blood cannot be sent to the part, and so
it gets well slowly. During sickness or a surgical opera-
tion a drinker is always in greater danger of his life than
he would have been if he had let drink alone.
131. Alcohol and the heart. — Alcohol acts as a stimulant,
and compels the cells of the body to do more work ; but
gives them no extra strength with which to do it.
70 APPLIED PHYSIOLOGY
The heart is the most regular and the best behaved
organ in the body, but alcohol makes it beat faster and
harder than the body needs. So it tires itself out, and
soon its beats become weaker. Thus a strong man weak-
ens his heart instead of making it stronger. The cells of
the heart's muscle, like the rest of the cells of the body,
do not get proper food, and so they become still weaker.
Alcohol gives a feeling of great strength to the body, but
this is due to weakness of the brain, which does not feel
fatigue as it should.
132. Tobacco. — Tobacco weakens and poisons all the
cells of the body, but it affects the heart more than any
other part. It causes the heart to beat more rapidly, and
at the same time with less strength. Sometimes the heart
beats slower than it should for a little while, and then
becomes rapid again. Sometimes its beat can be too
plainly felt. The result is that the smoker cannot work
so hard as he once could. His heart beats with violence,
but drives the blood with little force. He becomes very
short of breath, because the blood does not circulate in
the lungs as it should. When a young person's heart is
injured by tobacco, there is great danger that it will stay
weak all through life. Athletes, when training for a con-
test like running or rowing, do not smoke or chew, for
they know that to do so would weaken their hearts and
make them short-winded.
SUMMARY
1. The blood is a clear liquid containing albumin and
minerals. In it there float many red cells and fewer
white cells.
2. Tubes called arteries carry blood to all parts of the
body.
THE BLOOD AND ITS CIRCULATION J\
3. Fine tubes called capillaries receive the blood and
give it out to the cells.
4. Other tubes called veins carry the blood back to the
heart.
5. The heart is a pump which keeps the blood in motion.
6. Each stroke of the heart makes a wave in the arteries,
which we can feel as the pulse.
7. Cells eat the albumin and minerals which pass out of
the capillaries, taking the food in by any part of
their bodies.
8. The food which the cells do not use drains off in a set
of tubes called lymphatics \ which finally empty into
a vein near the heart.
9. When a part needs more blood, the arteries become
enlarged, and the heart pumps harder, so as to
carry more to it.
10. Alcohol makes the arteries larger and causes the
heart to beat quickly.
1 1. Tobacco poisons the muscle of the heart.
CHAPTER VIII
BLEEDING, WOUNDS, AND DISEASE GERMS
133. Bleeding. — When a person loses much blood, he
feels weak and faint, and if one half the blood is lost, he
dies. So bleeding is dangerous to life. We have seen
how the blood clots and stops bleeding. When a large
artery is cut, the force of the blood drives the clot out as
fast as it forms, and so there is great danger of bleeding
to death. Blood from a cut artery spurts out ; blood from
a cut vein only flows out, and does not spurt. So bleeding
from an artery is far more dangerous than from a vein.
134. How to stop bleeding. — Every one should know
how to stop bleeding. When dangerous bleeding occurs,
just squeeze the sides of the wound tightly together with
your hands. This is a sure and safe way of stopping any
bleeding until some one comes who can help you. But
sometimes a cut must be held for hours before enough
clot is formed to stop bleeding. So while you are holding
the cut you can get a handkerchief or any piece of cloth
ready so as to tie it tightly over the cut, or just above it.
Then a stick may be put under the handkerchief and
twisted tightly, so as to close the bleeding artery. There
is one important thing to remember : keep everything as
clean as possible, and put no earth or cobwebs, or any
other dirty thing upon the cut, for there is great danger
of poisoning the wound by it. If bleeding comes from
the arm or leg, very much less blood will go to the limb if
72
BLEEDING, WOUNDS, AND DISEASE GERMS
73
the person lies down and holds the limb straight up in the
air. In nosebleed, the person should sit up so that the
blood will not run to the head. If he presses the nostrils
together and breathes through his mouth, the bleeding will
soon stop. Then he should not blow the nose for some
time, so that the clot may have time to get thick and
surely stop the bleeding.
135. Injury to cells. — The cells of the body are always
likely to be hurt, and yet they quickly mend themselves
again. They are hurt by cuts, scratches, burns, and
bruises. A blast of cold air upon a heated part of the
body hurts the cells. But wounds are soon mended if we
do not take cold in them. We must explain what taking
cold is.
136. Bacteria of disease. — There are tiny living beings
called bacteria which grow everywhere in dead matter.
They produce decay,
and change dead bodies
to a form which plants
can use as food. With-
out them, dead bodies
would accumulate and
cover the earth. But
a few kinds can live in
the lymph between the
capillaries and the cells
of the body, and there
produce diseases. A
few of these seeds or
germs of disease are
everywhere in the air,
water, and soil, but there are very many in all kinds of
dirt and filth. A pin point can carry thousands of these
Bacteria growing in the mouth ( X 400) .
The specimen was obtained by scraping a
healthy mouth.
a nucleus of an epithelial cell.
b different forms of bacteria.
c outline of an epithelial cell.
74
APPLIED PHYSIOLOGY
germs into the skin. They seldom grow in the blood, for
it is in too rapid motion, but they do grow in the lymph
and produce millions of new bacteria. They may fall upon
a sore spot, or a cut, and so go into the lymph at once.
These bacteria live upon the lymph and give out poisons
which may make the whole body sick. Typhoid fever,
diphtheria, cholera, and erysipelas are kinds of sickness
caused by the bacteria. When a cut discharges matter,
it is due to the same thing. The growth of these germs,
and the effect of the poisons which they make, is what is
usually meant by "taking cold."
Bacteria are always ready to enter the lymph, and the
object of the physician and surgeon is to keep them out.
When the germs are
a
>»-»•,
kept out, heat and cold
and wet will not make
a person take cold in a
cut or wound of any
kind.
137. Inflammation. —
Whenever the body is
hurt, the first thing it
does towards mending
the wound is to loosen
the muscles of the arte-
ries going to the hurt
spot, so as to let more
blood go there. This makes the part red. Then the
white blood cells begin to stick to the sides of the finest
blood tubes and to pass through their sides into the
lymph spaces. At the same time more of the watery parts
of the blood leave the capillaries. This makes a swelling,
while the pressure of the swelling upon the nerves gives
^\fe
Beginning of inflammation (x 400).
a white blood cells adhering to the wall of a
capillary and passing through it.
b white blood cells which have passed out-
side of the capillary in order to repair an
injury.
c white blood cells passing through the capil-
lary.
d wall of capillary.
BLEEDING, WOUNDS, AND DISEASE GERMS 75
pain. The three signs, namely, redness, swelling, and pain,
generally mean that a part is inflamed.
138. Repair of wounds. — The object of the increased
quantity and action of the blood is to heal the injured part.
If some of the cells of a part have been killed by an injury,
the white blood cells eat up the dead parts and carry them
off with the lymph. Some of the white blood cells become
branched, and fit themselves into the spaces between the
cells, and so become a part of the flesh. Thus the cut or
injured parts are mended. The new flesh does not look
like the old, but is puckered and firmer. It is called a
scar.
139. Taking cold. — Now suppose bacteria are doing
damage to the body, or get into the lymph spaces after it
is done. Then they multiply and produce poisons which
harm the body far more than the first injury. The white
blood cells fight these bacteria. Whole armies of cells
rush to the spot and usually soon overcome the germs.
But many times the white blood cells are killed in the
fight. Then others rush in, until they pack the lymph
spaces tightly and fill the ends of the blood tubes and so
cut off the supply of food. So the bacteria are besieged
until they are starved to death, but the cells of the body
also starve. Finally the germs, the white blood cells, and
the cells of the body all die and soften and run out as
matter, or pus. This is called a gathering, or abscess. A
boil is an example of this. After the matter has run out,
the white cells grow over the bottom and sides of the hole
and soon mend it with a scar. So a few of the cells of the
body give their lives in order that the rest may be saved.
Those that were killed and formed the foul matter were
just as good and strong cells as those that were left and
healed the wound. They were not impurities in the blood,
76
APPLIED PHYSIOLOGY
but were its strongest and purest cells which went out to
fight enemies and were killed. After they die, they decay
and become poisons, and so must be thrown off.
The same thing happens in a cut. The bacteria grow
upon its surface, while the white blood cells fight them
until they are killed and flow away as matter. If the cut
An abcess ( x 50) .
a epithelium of the skin, softened and bursting.
b white blood cells which have packed the tissues full and shut out nourishment.
c blood tube stopped by white blood cells.
is kept closed and clean so that the germs cannot get in,
there will be no cold in the cut, but the white blood cells
will devote all their energies to mending the cut. Then
the cut will heal in a few days, without pain or much
inflammation.
When you sit in a cold wind after being heated by exer-
cise, the tender cells of your nose and mouth are hurt, and
you have a sore throat. Perhaps some bacteria grow there
too. Then white blood cells and liquid parts of the blood
pass out of the capillaries and form the thick matter which
we spit out. This does not consist of impurities of the
BLEEDING, WOUNDS, AND DISEASE GERMS JJ
blood, but it is what your body is using to mend the hurt
and to destroy the bacteria. We insult these little cells
when we call them impurities, while they are keeping off
enemies and yet mending the wound too.
\J40. The skin in healing. — While the white blood cells
are growing and healing a cut, the cells upon the surface
of the skin around the edge of the sore slowly spread over
it. This forms a new skin and ends the healing. This
new growth of skin is necessary in every healing process.
When the new flesh grows faster than the skin, the skin
cannot keep up with it, and so the flesh forms a soft red
tuft above the skin. This is called proud flesh, and must
be burned or scraped off before the skin can finish healing
the cut.
141. How to care for a cut. — Bacteria are everywhere,
and readily enter a cut unless they are kept out. The
surgeon keeps them out by wrapping wounds in cloths
which have been boiled or steamed in order to kill the
germs. He also puts on for the same purpose such things
as carbolic acid. In this way he can keep the germs from
the wounds which he makes, and so the white blood cells
will have nothing to do except to mend the wound. Then
in a few clays even the largest cut grows together and is
whole again.
When you cut yourself, the wound will soon heal if you
bind it up with a clean cloth and change this often enough
to keep the wound dry. Then no germs will grow in the
cut, and nothing will prevent it from healing. It will be
still better to put on the dressings something which will
kill the disease germs. One part of carbolic acid in fifty
of water is good. Friars' balsam is good, too. Do not
put on a sticky salve, for it keeps in the disease germs and
matter.
78 APPLIED PHYSIOLOGY
142. Catching diseases. — Some diseases," like measles,
smallpox, and typhoid fever are caught from other cases
of the same disease. These diseases are caused by some
germ which can live in the air or soil after it passes off
from the sick person. One may get these diseases by
breathing the air of a sick room, or by eating some of the
germs which stick to the hands or clothes, or by drinking
some well water into which slops from the house have
trickled. So great care must always be taken of a person
sick with a catching disease.
In the first place, a sick room needs plenty of air, even
in cold weather. This drives out the disease germs as fast
as they form. Sunlight also kills the germs. So it is
almost impossible to catch a disease in the open air.
In the second place, the sick room must be kept clean.
The bedclothes must be changed often and washed, and
the person himself must be bathed often. This also
removes disease germs.
In the third place, soiled clothing must be boiled to kill
the germs, or else they will carry the disease. Slops must
be buried, or else have carbolic acid or some such sub-
stance poured over them to kill the disease germs.
In the fourth place, you must avoid handling the patient
or his dirty clothes. When you come from the sick room
you must not eat without washing your hands. You must
not put your hands or fingers to your mouth in the sick
room.
143. Effects of alcohol. — Since alcohol starves and poi-
sons the cells, the white blood cells suffer with the rest,
and are not able to fight bacteria or to repair injuries as
they should. So inflammation is more likely to take place.
A drinker is more likely to get pneumonia or consumption
or other disease of the lungs, Alcohol scalds the throat,
BLEEDING, WOUNDS, AND DISEASE GERMS 79
and makes it tender and more likely to take cold. Thus
the voice of the drinker is often so hoarse that he is unable
to sing or talk. Far from protecting against disease or
taking cold, alcohol causes a person to be more liable to
sickness.
SUMMARY
i. You can stop any bleeding by grasping the part and
making firm pressure.
2. When a part of the body is injured, it soon repairs
itself.
3. Disease germs, called bacteria, can grow in the body.
A pin prick may carry thousands of them inside the
body.
4. Bacteria grow in the lymph, and produce such diseases
as erysipelas and typhoid fever.
5. When a part of the body is hurt, the white blood cells
rush to the spot and grow in place of the dead cells,
and so heal the wound.
6. When germs of disease grow in the body, the white
blood cells attack them. Matter which' runs from a
wound is made up of the cells which the disease
germs have killed.
7. Taking cold means that bacteria are growing in some
part of the body.
8. Cleanliness, to keep out bacteria, is the main thing in
treating a cut.
9. Cleanliness, fresh air, and sunshine are the main things
in caring for a sick room.
CHAPTER IX
RESPIRATION
144. Use of the breath. — The body is an engine, and its
power is made by burning or oxidation. Every cell in the
body must breathe in oxygen from the air, but only a few
on the surface have access to it. So a few cells are set
apart for the work of carrying it to the rest. Air is always
going in and out of the nose or mouth. When we stop
breathing for only a few seconds, we feel short of breath,
and if we should stop for a few min-
utes, we should die. Air, then, is the
most needful thing which we take into
our bodies.
145. The air passages and the lungs.
— The nose opens into the pharynx,
which is just back of the mouth. From
the pharynx there is an opening into
the windpipe. The windpipe is a tube
about six inches long. It branches
into two tubes called bi'oncJii, one for
each side of the body. Each bronchus
divides like the branches of a tree. At
the ends of the smallest twigs are tiny
bags or sacs, with very thin sides. The sacs can be
blown up with air. The bronchi and air sacs make up
the lungs. The lungs are light red flesh, much like a
sponge. The air in them crackles when they are squeezed.
80
A frog's lung (x 4).
RESPIRATION
81
Look at the lungs of a pig or calf in the butcher's shop,
for they are like a man's lung. A frog's lung is a thin
bag, about half an inch in diameter. Upon its sides are
shallow cups like the
pockets of a honey-
comb. Each air sac of
a man's lung is like a
very small frog's lung.
146. Breathing. —
The lungs are hung in
a box called the chest
or thorax. The sides
of the chest are the
ribs, and its bottom is
a leaf of muscle called
the diaphragm, which
stretches like an arch
across the inside of the
body. (See page 22.)
The ribs and diaphragm
can be moved so as to
make the chest larger or
smaller. When it be-
comes larger, the air
is sucked into the lungs
and makes them larger.
This is called inspiration.
The air tubes and lungs.
a larynx or voice box.
b trachea or windpipe.
c bronchi.
d air sacs, each like a tiny frog's lung.
When the chest is made
smaller, air is driven out of the lungs. This is called
expiration. This takes place about eighteen times a
minute, but when you run or work hard you must breathe
more often.
147. Cilia. — The lining of the windpipe and bronchi is
made of cells whose inner ends are covered with tiny hairs
OV. PHYSIOL. (INTER.) — 6
82
APPLIED PHYSIOLOGY
always in motion. The hairs vibrate in such a way as to
drive anything out of the air passages. In the finest
bronchi they reach a considerable way across the tube and
entangle any dust which may reach them. So they pro-
tect the delicate air sacs from dust. They * also force
mucus towards the mouth, so that we can get rid of it
-</
A slice from the trachea ( X 200) .
a cartilage. b glands in the mucous membrane.
c lining of epithelial cells.
d cilia upon the surface of the epithelium.
when we have a cold. Finally, the cilia make air currents
in the tiny air tubes, and so hasten the exchange of pure
for impure air.
"148. Breathing sounds. — As air goes in and out of the
lungs, it makes a low, blowing sound. Listen to each
other's chests while breathing deeply and notice these
sounds of breathing. Listen, also, while a person counts
three. You will feel the chest tremble and hear the voice
through the chest. The physician listens to the chest
when he thinks a person has lung disease. By the
RESPIRATION
83
Capillaries upon the sides of an air sac
(x 200).
changes in the sounds he can tell what is the matter with
the lungs.
149. What air does to the blood. — The air is four fifths
nitrogen and one fifth oxygen gas. Both gases go into the
air sacs of the lungs, but
all the nitrogen comes
back, while some of the
oxygen is left behind, and
some carbonic acid gas
and water are put in its
place. We must see what
becomes of the oxygen.
Upon the sides of the air
sacs is a close network of
capillary blood tubes.
Their sides are very thin.
While they keep the blood
from running out, they let oxygen gas pass through very
easily. The red blood cells are oxygen carriers, and as
they shoot through the capillaries they take tiny loads of
oxygen and carry it to
all parts of the body
for the use of the cells.
Each load of oxygen
causes its red blood cell
to become bright red in
color, and so the whole
blood becomes a brighter
red as it passes through
the lungs.
150. How air reaches the cells of the body. — From the
lungs the blood goes to the left side of the heart and is
sent through the capillaries to all parts of the body.
Diagram of the respiration of cells.
84 APPLIED PHYSIOLOGY
Not even oxygen can pass through the sides of the arte-
ries, but when it reaches the capillaries it passes out very
easily. So in the capillaries it leaves the red blood cells
and goes to the cells of the body. When oxygen has left the
blood cells, they become of a darker color. So blood in the
veins is always of a darker color than blood in the arteries.
^151. Oxidation in the cells. — The oxygen which goes to
the cells of the body burns, or oxidizes, their albumin, fat,
and sugar, producing carbonic acid gas and water. All
oxidation inside the body takes place in a living cell.
Oxidation is the real act of breathing. The cells of the
body are always getting oxygen and giving out carbonic
acid gas and water. The water drains off by the lymph.
The carbonic acid gas goes through the sides of the capil-
laries and so back to the blood, where it is dissolved and
carried to the lungs. So blood in the veins has less oxygen
and more carbonic acid gas than blood in the arteries. It
is the lack of oxygen, not the presence of carbonic acid gas,
that makes the venous blood dark in color.
152. How carbonic acid gas leaves the body. — All the
venous blood flows into the right side of the heart and is
pumped to the lungs. In the lungs the carbonic acid gas
leaves the blood and passes off through the sides of the
capillaries into the air sacs. It is then breathed out by the
next breath. At the same time, oxygen passes to the red
blood cells again, and the blood is ready for another round
of the body. So the blood carries oxygen to the cells of
the body and gets carbonic acid gas from them, and then
goes to the lungs to give up the carbonic acid gas in
exchange for oxygen from the air. The real breathing in
the body is done in the capillaries and cells. The lungs
are places where the red blood cells get oxygen to carry to
the cells.
RESPIRATION 85
153. How rapidly oxygen is used. — When the draft of
a stove is closed, the fire stops burning at once. Just so
the oxidation in the body stops when we stop breathing.
In a lung full of air there is enough oxygen to last from
one half to one minute. After that we feel very short of
breath and cannot keep ourselves from breathing. A frog
can take a big mouthful of air which will last him some
time while he is under water, but finally he must come to
the top for more air. A man cannot store air in his body,
and so must keep taking in air every moment. The oxy-
gen goes quickly to the cells, and starts the oxidation at
once. A few deep breaths will relieve almost any short-
ness of breath.
154. Why we get short of breath. — When we run or
work hard, our cells use a great deal of oxygen. Then
we breathe deeper and take in more oxygen. But after
a while the red blood cells have all they can carry. Then
we cannot get more, but feel very short of breath. So we
stop work until we have sufficient oxygen again. By train-
ing, we can educate the heart and lungs so that more
oxygen may be carried. Then we can run a long distance
without getting out of breath.
155. Mouth breathing. — You should always breathe
through the nose. This warms the air and strains out its
dust. When you breathe through the mouth, the cold air
and dust make you cough and are very likely to give you
a cold.
Some children have masses of flesh growing either in
the throat, pharynx, or the nose. Such children always
keep their mouths open, for they cannot breathe through
the nose. The upper lip seems too short for their teeth.
The jaw is narrow and the teeth point forward. This
deforms the face for life. If these masses are removed
86 APPLIED PHYSIOLOGY
early, as can be easily and painlessly done, the jaw will
grow into proper shape, and allow the child to breathe
through its nose and become well again.
Many children breathe through the mouth from habit.
They should keep from it even when they feel short of
breath.
Another reason why a child should not breathe through
the mouth is that it may produce earache.
156. Deep breathing. — The larger your lungs are, the
more air you can take in. So you ought to take a deep
breath several times a day. Then hold your breath as long
as possible. In this way you will increase the size of your
lungs and become able to run a long distance. It will also
make you stronger all over, and be a great protection
against your taking diseases.
A man should be able to make his chest two inches
larger around with each breath. Three or four inches
will be better. The more you can expand your lungs, the
longer-winded you will be.
157. Position of the body. — You should always keep
your shoulders thrown back and your chest forward, so as
to give the lungs all the room you can. A round-shouldered,
flat-chested man has little room for his lungs.
158. Tight clothing. — When your clothes are tight
around the body, you cannot expand your lungs so much
as you wish, and so you cannot run or work without getting
out of breath. If you wear tight clothes day after day,
your lungs will finally grow small and you will never be
strong.
The waist should be large around so as to give room for
the liver as well as the lungs. Girls need as much room
for their livers and lungs as boys. They do a great deal
of harm to themselves by making their waists small.
RESPIRATION
87
159. Artificial respiration. — We can breathe as we
choose for a few moments, but nature finally makes us
breathe as we
should. Some-
times a person
is injured in
such a way that
he cannot
breathe. In
drowning or an
electric shock a
person stops
breathing. If
he can only be made to breathe again, his life will be
saved. Every one should know how to make a person
breathe.
When any one presses your chest or stomach, it drives
the air out of your nose and makes a sound. In the same
Diagram of artificial respiration, showing inspiration.
The arrows show that the arms are moved outward
from the sides of the chest.
frp>ra,/r
way you can
make air pass in
and out of a life-
less body by
pressing upon the
ribs. If you press
as often as you
yourself breathe,
Diagram of artificial respiration, showing expiration, the body will °"et
The arrows show that the arms are carried directly for- 1 ...
ward until they are pressed hard against the chest. a lar&e quantity
of air. So if a
person seems dead from drowning or electric shock, try to
perform his breathing for him. You can do no harm and
you may save his life.
160. How to make a lifeless person breathe. — Here is a
88
APPLIED PHYSIOLOGY
good way to perform artificial respiration : Lay the person
upon his back. Kneel down at his head and grasp his
arms at his elbows. Now sweep them out from his body
and bring them nearly together above his head. This
expands the chest and draws air into the lungs.
Next, sweep the arms downwards and press them hard
against his chest. This will force the air out of the lungs
and will probably make a sound. Keep this up about as
often as you breathe. You may need to keep doing it for
an hour or two before a person revives.
4161. Drowning. — In cases of drowning, the lungs will
contain some water. Then you should turn the person
upon his face and lift him by his chest so as to allow the
water to drain out
— a
Back view of the larynx.
a thyroid cartilage.
b vocal cords.
c movable cartilage for the
attachment of the vocal
cords.
d cricoid cartilage.
e epiglottis.
Adams Apple.
are stretched,
slide sidewise
Do this for a few seconds, and then
keep on with the artificial respira-
tion. Do not get hurried or excited.
Remember that the life of the per-
son may depend upon your causing
slow and continuous breathing. Do
not wait for help, but begin at once.
162. The voice. — By means of
the breath we talk, and laugh, and
cry, and sing, and make all kinds
of sounds to express our thoughts
and feelings. Nearly all of these
sounds are made in a little box called
the larynx, in which the windpipe
begins. Its outside can be felt in
the upper part of the neck, under
the chin, where it forms "the
Across the middle of the box two bands
These bands are called vocal cords. They
and can be made either tight or loose.
RESPIRATION
89
When they are tightened and brought near together, and
a breath of air is driven out through them, a noise is made.
The sound varies with the tightness and the nearness to-
gether of the cords, and the force with which air is driven
out. It is further changed by the mouth and nose, which
act as a sounding box. In talking, the tongue and lips are
moved so as to make different kinds of sounds. These
sounds are so very much alike that the sounds of a for-
eigner's language seem the same, no matter what he is
saying. Yet we learn to make the sounds with great ex-
actness and rapidity, and to tell their difference easily.
Top view of the larynx, with the
vocal cords closed, as in speaking.
a epiglottis. b vocal cords.
Top view of the larynx, with the
vocal cords open, as in breatMng.
a epiglottis. b vocal cords.
163. Care of the voice. — The larynx becomes tired, like
any other part of the body. So it is harmful to strain the
voice by loud shouting or singing. Breathing through the
mouth is also harmful, especially if the air be cold or
damp. Using the voice while the throat is sore is also
harmful. Singing notes of very high pitch is also very
tiresome to the voice.
It is easy to form the habit of talking in loud, coarse
tones. Now the tones of the voice express our feelings.
We ought to be careful always to speak in pleasant tones
so as to make others feel happy even if we are not happy.
Then we ourselves shall be more likely to be happy.
164. Alcohol and oxidation. — We have already studied
90 APPLIED PHYSIOLOGY
the process by which alcohol is carried to the liver, and
there takes the oxygen which should go to oxidize the
albumin, fat, and sugar of the body (see § ioo). So when
alcohol is used, not only the liver, but also all other cells of
the body lack oxygen, and cannot work as they should.
It should be remembered that alcohol is oxidized in the
liver, and that none reaches the other cells of the body.
Two or three drinks of whisky use as much oxygen as
the whole body uses in an hour. So the cells of the body
cannot breathe properly when strong drink is used.
165. Alcoholic breath. — When alcohol is swallowed,
some remains in the throat and gives a bad odor to the
breath. But it also hinders digestion and produces a
coated tongue and biliousness. This gives a still worse
odor to the breath. Alcohol itself does not go off by the
breath, for it is oxidized in the liver.
166. Tobacco and the lungs. — The nicotine of tobacco
has a sharp, peppery taste, and makes the throat tender
and the voice hoarse. It hurts the nerves, so that there is
a feeling as though something were stuck in the throat.
Trying to cough it out strains the throat. By keeping the
throat tender in this way a person makes himself more
liable to take cold. Tobacco smoke in the windpipe and
bronchi is still more harmful, for these parts are more ten-
der than the throat. Instead, then, of making a singer's
voice clear and strong, it makes it hoarse and weak.
Tobacco smoke has the same poisons as tobacco itself,
besides other poisons developed by the burning. All these
poisons in the smoke can enter the body. Cigarette smoke
is drawn deeply into the lungs. Consequently it is more
likely to remain in the body and poison the smoker. Of all
forms of smoking, cigarette smoking is the most harmful.
Yet many boys suppose it to be the least harmful form.
RESPIRATION 9 1
167. Adulterated tobacco. — Some cigars, cigarettes, and
chewing tobacco have substances added to improve their
taste. For this purpose, molasses, licorice, vanilla, and
the like, are added. Some of these things do harm, and,
in any case, the addition of such substances is a fraud.
SUMMARY
1. The lungs are made of tiny sacs, upon whose sides
capillaries are spread.
2. By moving the chest walls, air is drawn into the lungs
and forced out again.
3. As the red blood cells shoot through the capillaries of
the lungs, they take up tiny loads of oxygen from
the air. This makes the blood bright red in color.
4. The blood carries oxygen to the capillaries of the body.
There the oxygen goes to the cells of the body.
5. The oxygen oxidizes the cells to carbonic acid gas and
water. Thus the cells breathe.
6. The blood carries the carbonic acid gas to the lungs,
and gives it out to the air.
7. When the cells have used all the air in the blood, we
feel short of breath.
8. We should breathe deeply and through the nose. We
should sit and stand straight, and wear loose clothes,
to give our lungs room.
9. In a case of drowning, you can make air enter and
leave the lungs by pulling the arms above the head
and then pressing them against the chest. Do this
as often as you yourself breathe.
10. Air passing between two cords in the larynx makes
the sound of the voice.
11. Alcohol takes oxygen from the cells of the body.
12. Tobacco smoke irritates and poisons the lungs.
CHAPTER X
VENTILATION, HEAT, AND CLOTHING
168. Need of fresh air. — Since oxygen is taken from
the air and carbonic acid gas goes out in its place, the
air in a short time becomes unfit for use unless it is
changed. Carbonic acid gas is but slightly poisonous in
itself, or else the body would always be poisoned, but
when it is breathed into the air the same amount of
oxygen has been taken away from the air. Only a little
oxygen can be taken away from the air before the body
feels the loss. In a church, the windows are sometimes
closed tightly and but little new oxygen can get in to take
the place of that which is breathed. So there is not
enough oxygen to keep up the full oxidation within our
bodies. As a result, their power is lessened, and we
become so sleepy that the best sermon does not keep us
awake.
169. Foul air. — Water is always evaporating from the
nose and mouth and going out by the breath. Odors from
the mouth and clothes also enter the air. The moisture
and odors are very unpleasant to sensitive persons and
may of themselves cause sickness. Disease germs, such
as those of measles and smallpox, are often given off by
unclean persons. They are no more poisonous in a close
room than out of doors, but in a room they are not scat-
tered by the wind, and so another person is far more likely
to breathe them in than he would be in the open air. So a
92
VENTILATION, HEAT, AND CLOTHING
93
change of air is very necessary where people are together
in a tight room.
170. Ventilation. — Changing the air of a room is called
ventilation. In large buildings it is often done by fans
and pumps, but in most buildings it is done by natural
Diagram of the natural ventilation of a room.
The arrows indicate the direction of the air currents.
currents of air. Breathed air is warmed in the lungs.
Warm air is lighter than cold air and so rises to the ceil-
ing. If the upper part of the window is opened, the
warmed air will pass out while the fresh air will enter by
cracks in the doors and lower parts of the windows. On
a cold day the difference between the warmed and cold
air is very great. This causes a strong current ; but on
94 APPLIED PHYSIOLOGY
a hot summer's day the breathed air is of about the same
warmth as the air outside ; so there will be no current
unless the wind blows. This makes buildings very warm
and close in the summer.
171. How to ventilate. — When only one or two people
live in a room, the ventilation by cracks in the doors and
windows is enough and in very cold weather may be too
much. In new and very tightly built houses, the cracks
are few and small, and more ventilation will be needed.
The simplest way to ventilate a room is to raise or lower
a window. But then the cold fresh air may blow on some
one's head and cause a cold. So you must be careful to
open a window through which the wind will not blow.
Another way is to raise the lower window sash and fit a
board to fill the opening. Then the fresh air will come in
between the two sashes and will make less of a draft.
Some houses are heated by hot-air registers. If the air
in the register is pure, this will ventilate the room. Some-
times an opening is made in the chimney near the ceiling
so that the impure air can get out ; then more pure and
warm air will come in. In large buildings like schools and
theaters, there is often a fan run by machinery. This
forces out the impure air and fills the room with pure air.
So the air can be changed as fast as we wish.
172. Sick rooms. — It is very important to ventilate a
sick room, for sick persons need all the oxygen they can
get. They should not be disturbed with unpleasant odors.
Especially in some kinds of sickness, disease germs need
to be carried away as fast as they are given off.
173. Bedrooms. — Night air is exactly the same as air
in the daytime, except that it is cooler. Sleeping rooms
should be as freely opened to the air at night as in the
daytime. The air of any room ought to be changed often
VENTILATION, HEAT, AND CLOTHING 95
enough to prevent any odor in the room, for air that has
no odor is generally pure and safe for use.
«e 174. Warmth of the body. — Heat is produced by oxi-
dation. This warms the whole body and also gives it
power to think, and move, and work. Oxidation takes
place in every cell of the body, but most of the fat is
oxidized in the cells of the lungs, and most of the sugar
in the cells of the liver. Muscle cells also produce a
great deal of heat when they work. The body has the
power of making its fires burn high or low as its work
needs, but its own warmth always remains the same. A
thermometer shows its temperature to be 98.5 degrees F.,
whether we feel warm or cold.
175. The feeling of heat and cold. — We sometimes feel
very warm and again very cold, but our bodies always
have the same degree of heat. We feel warmth mostly
in the skin. So if the skin is warm, we feel warm all
over, but if it is cold, we feel chilly all over. In fevers a
sick person often feels very cold, for his skin may be cold
while his body may really be in a hot fever.
176. How the body varies the heat. — When we work
hard, we need a great deal more heat than when we are
still. In winter we also need much heat to warm the body,
while in summer we need but little. So we must vary
the amount of heat. We can do this by varying our food.
Fat makes a great deal of heat. So in winter we like fat
meat. In summer we do not like fat so well, but prefer
fruit. This has little fat, but a great deal of sugar, which
produces less heat. In winter we eat more food than in
summer. When- we move about, we are warmer than
when we keep still. So in winter we feel like working, for
we need the heat of exercise to keep ourselves warm.
177. How the skin gives off heat. — The body has a
96 APPLIED PHYSIOLOGY
temperature of 98.5 degrees F. A room at this warmth
would seem hot to us. Even 80 degrees F. is too warm.
70 degrees F. seems about right. This is only a little more
than half way between freezing and the warmth of our
body. So heat is always passing off from the skin and
warming the air. We get rid of a great deal of heat in
this way.
On a cold day the heat goes off faster than on a warm
day. Then we should expect our bodies to be colder.
But nature causes the blood tubes of the skin to become
smaller so as to keep some of the blood away from the
skin. Then no more than the right amount of heat will
pass off, and we shall still feel warm.
On a warm day the heat will pass off from the skin
more slowly. Then the blood tubes in the skin become
larger, and bring more blood to the surface. Thus more
heat can pass off, and the body will be kept at the right
warmth.
178. How the perspiration affects our warmth. — A wet
skin always feels cold, even if the water is warm when it
is put on the skin. This is because the heat passes off in
the steam as the water dries. The skin is always moist
with sweat or perspiration. We cannot see it, for it passes
off as fast as it comes out. But as it dries, it takes away
a great deal of heat.
On cold days only a little perspiration is poured out, for
enough heat will pass off without it. On warm days a
great deal will often be produced, so that it may not dry
so fast as it is formed. Then it collects in drops, and
even runs down the face.
The perspiration enables us to endure great heat. Men
have staid in hot ovens for some time without injury, for
the perspiration carried the heat away from their bodies.
VENTILATION, HEAT, AND CLOTHING 97
179. Fever. — When the body becomes too warm, we
are in a fever ; and are sick. If the temperature of the
body is only one or two degrees too much, we do not feel
well. A temperature of 105 degrees F. is a high fever,
and is dangerous to life.
When we have a fever, we are very thirsty. Then we
ought to drink cold water. This will help to lower the
fever, and will also help to wash away the poison of the
disease. It is also a good plan to bathe the body often
for the sake of cooling it. Keep the room cool, and
have little bed covering, for the sick person needs to be
cooled, and he is in little danger of catching cold.
180. Sunstroke. — When exposed to a great heat under
a hot sun or in a hot room, the body sometimes gets too
warm. Then the person suddenly feels sick and faint.
He is suffering from a suiistroke. This is a dangerous
condition. It is most likely to occur on hot, damp days.
On such days babies are very apt to become sick from the
heat.
In sunstroke the person should be carried to a cool spot.
Put cold water or ice to his head and body so as to cool
him as soon as possible. He will need a long rest after he
recovers.
181. r Burns. — A temperature of 120 degrees F. is all the
skin can endure. Above this the heat produces a smart-
ing pain, and injures or kills the skin. If the heat is very
great, the whole thickness of the skin may be burned.
When a person is burned, put cold water upon the burn at
once, so as to stop the pain. Then put on some common
baking soda, or some oil of any kind. A mixture of lin-
seed oil and limewater is always good. This soothes the
pain, and keeps the parts soft. Healing will take place
slowly. Use the oil dressing until the burn has healed.
OV. PHYSIOL. (INTER.) — 7
98 APPLIED PHYSIOLOGY
182. Burning clothing. — If the clothes catch fire, they
are very likely to burn a person to death. The great
danger is that the fire may be breathed into the nose
and lungs. So a person whose clothes are on fire should
lie down at once. This will also keep the flames from
spreading over his whole body. If he now roll over and
over, he will be very likely to smother the flames. At
any rate, they will spread slowly, and will not reach his
face.
If you see a person's clothes catch fire, at once throw
him to the floor and roll him about. You can also wrap
your coat or the carpet about him, and thus smother the
flames.
183. Effects of cold. — When a person is exposed to very
intense cold he becomes drowsy, and finally falls asleep.
Then he is near death unless he is aroused. So when
a person is very cold you must not let him rest, but keep
him moving about.
When a part of the body, as a hand or an ear, is very
cold, it becomes numb so that it cannot feel. Then we
may think the part is warm, since we no longer feel the
cold. But soon it may freeze.
Freezing is very apt to kill the part frozen. Rub it with
snow, or place it in ice water and let it grow warm very
gradually. If it is thawed quickly, it will surely die, but
if it thaws slowly, it may finally get well, but it will be
sore and will smart and itch for a long time.
184. Catching cold. — When one part of the body is
colder than another, the blood is driven from the cold part
and collects in other parts of the body. . This disturbance
is very apt to injure the cells and make us take cold. For
this reason damp and cold feet are liable to cause sickness.
We ought to wear thick-soled shoes or rubbers on every
VENTILATION, HEAT, AND CLOTHING
99
wet day. We ought to be very careful how we cool our
bodies when we are very warm. We are liable to catch
cold if we go from a warm room into the cold air without
putting on extra clothing.
185. Heating houses. — In cold weather we cannot keep
warm without warming the air, so that less heat will pass
off from the body. When houses were heated with open
fireplaces, there was a roaring draft up the chimney with
perfect ventilation, but the room was always cold only
a little way from the fire. Now we use stoves. They do
not use much air and so do not give much ventilation.
If they give off dust and gas, they may make the air bad.
In many houses, a furnace in the cellar is used to send
heat through pipes to all the rooms. This gives a great
deal of ventilation and is a good way of heating. Steam
in pipes is also used to heat houses. This heats the rooms
well but does not afford any ventilation. When it is used
we must be careful to let in enough fresh air.
Kerosene stoves, or other kinds of fire in which the
smoke and burned products do not pass off through a
chimney, are the worst ways of heating, for they not only
use the air but they also pour foul gases into it.
186. The proper warmth of a room. — The best tempera-
ture for a house is about yo degrees F. This feels neither
too warm nor too cold. For a bedroom the temperature
should be 6o degrees F. or less.
187. Clothing. — Sometimes nature cannot keep us warm
enough in cold weather, or protect us from the heat of
summer, and so men protect themselves with clothing.
In cold weather our object is to keep the heat from pass-
ing off from the body, and we wrap ourselves in thick
clothes. Clothing simply keeps in the heat of the body
without adding any new heat.
100 APPLIED PHYSIOLOGY
188. Fur. — Fur lets the least heat pass off and so
makes the best winter coat. The air between its separate
fibers is a great help in keeping in the heat. When the
fur is matted down, it lets more heat pass out and is not
so warm.
189. Woolen. — Next to fur in warmth is woolen cloth-
ing. Soft cloth is warmer than hard or stiff cloth, for it
holds more' air. Silk is even better than wool to keep
in the heat.
190. Cotton. — Cotton lets heat pass through it readily,
and so is cold clothing. Linen lets heat pass through still
more easily, and is still colder; but if enough cotton or
linen is worn, it will keep in the heat, and so keep the
body warm on a cold day. When linen or cotton under-
clothing is worn, a slight draft of air chills the body, for
the underclothing does not keep in the heat, and so a
person is liable to take cold.
191. How to clothe the body. — If a person wears woolen
underclothing, little drafts of air have no effect in taking
away the heat, and so he does not notice slight changes
of the weather. In warm weather we wish to let the heat
of the body pass off, and so we wear cotton or linen.
Black cloth lets more of the sun's heat pass through it
than white cloth, so white clothing is the cooler when we
are exposed to the sun.
In winter we should wear woolen next to the skin so as
not to feel sudden changes of temperature. Delicate
persons should wear woolen all the year.
When we go from a warm room into the cold air we
should put on an overcoat or wrap of some kind so as to
avoid a sudden chill. When we work hard and become
very warm we should not stop to rest without putting on
our coat.
VENTILATION, HEAT, AND CLOTHING ioi
Lying upon the damp ground is dangerous, for it may
make our clothes damp. This will cool one part of the
body more than another and cause us to take cold.
Bundling the neck and ears while the legs and feet
have no more covering than usual makes the head tender
and often causes us to take cold. Then, since our feet
are cold, we are almost certain to take cold. We had
better cover the feet more warmly and not wrap up the
head and neck.
We ought always to wear enough clothing to keep us
warm. It is a mistake to think that we can get used
to the cold by going without proper clothes. We shall be
more liable to take cold and shall make ourselves more
tender than ever. But we ought not to wear so much
clothing that we are too warm.
192. Tight clothing. — The blood carries heat to all
parts of the body. When the blood does not flow well
through a part, that part becomes cold. If we wear tight
garters or shoes, the blood cannot flow through the feet
as it should. Then we have cold feet. Tight clothing
of any kind makes us cold.
• J.93. Paper clothing. — If paper were only stronger, it
would make one of the best kinds of clothing. When
we have too little clothing we can keep warm by putting
a newspaper around the body under the coat or waistcoat.
At night a few newspapers between the quilts will make
us much warmer.
194. Cold-blooded animals. — Some animals, like frogs
and snakes, breathe but little. They do not produce
enough heat to make themselves much warmer than the
air. On cold days they are dull and sluggish. In winter
they are stiff and do not move, but lie buried in the mud
or earth. Yet they breathe enough through their skins to
102 APPLIED PHYSIOLOGY
keep themselves alive. On hot summer days they are
lively, for then they can form enough heat to keep them-
selves warm and have some left over with which to work.
195. Alcohol and warmth. — Heat is produced by the
oxidation of alcohol. But it would be entirely wrong to
think that it makes the body really warmer. The body
does not like the heat which is produced in this way, but
it at once tries to get rid of it by sending more blood
through the arteries of the skin. This makes the skin
warm and red, and the drinker says that he knows he
is warmer because he feels so. His skin is really warmer,
but this is because the heat is coming to the surface and
is passing off. He loses more heat than he gains. Often
his skin begins to perspire so as to get rid of still more
heat. Men are deceived by this feeling of warmth more
than by any other thing about alcohol, and some people
who will not drink at any other time will drink before
starting upon a cold ride. This is the worst time of all
to drink. It brings the blood in contact with the cold air,
and so more heat is lost. After the heat from the oxida-
tion of the alcohol has passed off, the skin becomes cold
once more, and the body feels colder than ever. But it
was really colder all the time.
SUMMARY
1. The air of inhabited rooms is continually being made
foul by the breath and by vapors given off from
the body. Its oxygen is also removed by breathing.
2. We must change the air of a room often enough to
keep away all odors from the air.
3. Heat is produced by oxidation in the cells. This
warms the body and also furnishes it with power to
do work.
VENTILATION, HEAT, AND CLOTHING 103
4. The skin gives off heat by contact with the cool air
and by its perspiration.
5. Heat is always given off at such a rate as to keep the
temperature of the body at 98J degrees Fahrenheit.
6. When the body is too warm we have a fever and are
sick.
7. The ordinary feelings of cold and warmth are due to
the state of the nerves in the skin.
8. Burning or freezing a part kills the cells. Thaw a
frozen part very slowly.
9. We should keep a room warmed to about 70 degrees
Fahrenheit.
10. Clothing retains the heat of the body, but does not
make new heat.
11. The oxidation of alcohol develops heat in the body,
but it causes more to be given off through the skin
than was produced.
CHAPTER XI
THE SKIN AND KIDNEYS
196. The derma. — The whole body is covered with a
coat of woven cells called the skin. The skin of man is
from one sixteenth to
one eighth of an inch
in thickness. It is
made mostly of tough
cells like strings, and
contains more blood
tubes and nerves than
almost any other part
of the body. This
thick part is the true
skin. It is called the
derma or cutis. The
derma of animals when
tanned makes leather.
The nerves of the skin
end in little pointed
shoots of derma called
papilla. Rows of pa-
pillae make the fine lines
upon the palms of the
hands. The derma is
bound loosely to the
muscles and deeper parts of the body so that it can move
104
The skin (x 100).
a dead layer of epidermis.
b growing layer of epidermis.
c layer of cells containing the coloring matter
of the skin.
d papilla.
e sweat gland.
f small blood tube.
g fibers of the derma.
h fat cells in the derma.
THE SKIN AND KIDNEYS IO5
easily. It can be pinched up and stretched, but lies flat
and smooth again as soon as it is set free.
197. The epidermis. — Upon the outside of the derma
is a thin layer of scalelike cells called the epidermis. The
cells are called epitJielinm. They resemble those which
cover a mucous membrane (see p. 18). The epidermis has
no blood tubes or nerves, and so can be cut or pricked
without bleeding or giving pain. Its cells are formed upon
the top of the derma and are soft at first, but as new ones
grow, the older ones become hard and are finally shed or
rubbed off. These hard scales protect the nerves and
soft parts of the skin. Where the epidermis is gone and
the nerves are touched directly, the part is very sore
and tender. The papillae reach into the epidermis so as
to feel more easily.
Upon parts of the body which are rubbed, the epidermis
grows thicker and harder, so as to protect the deeper parts
better. This is called a callus. Rubbing the skin too hard
hurts the deeper scales of the epidermis, and then water or
blood collects under them and raises the epidermis into a
little bag of fluid called a blister. In the deepest parts of
the epidermis there are colored cells which give the skin
its color. A negro is black only in a very thin layer of
the deepest part of the epidermis, and his color is not even
" skin deep."
198. Nails. — The cells of the epidermis at the end of
each finger and toe are matted together to form a single
thick and hard scale called a nail. The nails protect the
flesh and form a kind of knife with which we can cut
and make marks. They also can form a pair of pincers
with which we pick up and hold small things. The cells
of the nail are formed nearly as far back as the joint of
the finger or toe. As new ones are formed the nail is
io6
APPLIED PHYSIOLOGY
forced ahead, and so it grows long and needs to be cut
off even with the ends of the fingers, with a sharp knife or
scissors. When the nails are bitten off, they are left rough
__^a and are likely to catch
- -Z- 7 — ~ "— -~—~ ~~- J} m the clothing and tear
away from the flesh.
Biting the nails also
makes the ends of the
fingers soft and sore.
i99. Hangnails. —
Sometimes a little tongue
of skin at the root of
the nail becomes torn up
and hangs by one end.
This is called a hang-
nail. They are some-
times very sore, and biting
them off makes them
worse. They should be cut off close to the skin with a
sharp knife. Sucking the fingers, or biting the nails, is
likely to cause these hangnails.
Dirt under the ends of the finger nails is not only untidy,
but may be poisonous. The nails themselves are not poi-
sonous, but the filth which they carry may contain germs
of sickness. So we ought to keep our nails clean. .
200. Hair. — Little tubes of epithelium from the epi-
dermis reach into the derma, and as fast as their cells
grow they are matted together into a string called a hair.
As new cells are always forming, the old ones are pushed
out, and so the hair grows. When a hair is pulled out,
the cells lining the tube keep on growing and soon make
a new hair. Fine hair covers nearly all the body, but upon
the head and upon men's faces, it grows long.
A nail ( x 200) .
a surface of the nail.
b body of the nail.
c epithelial cells just before they are welded
into a nail.
d papilla.
e growing epithelium.
THE SKIN AND KIDXKVS
IO/
.~
_/>
At the roots of the hair are the openings of small glands,
which make an oily substance. This oils the hair and
skin, and makes it soft and glossy. Each hair has a little
muscle, which can pull upon the hair so as to make it
stand straighter.
Cold air makes
the little muscles
act, and pulls
the hairs of the
body straight
up, so that their
roots form little
points above the
flesh. We call
these points
goose flesh.
\ 201. Care of
the hair. — The
short hair of
the body seems
to be an aid in
feeling. The
hair of the head
grows long for
ornament and
protection. A healthy person produces enough oily sub-
stance to keep the hair soft and glossy. If the hair is
brushed so as to keep it clean and to spread the oil over
it, it will look well without using hair oil or powder. On
the other hand, most hair oils and restoratives contain
substances which are harmful. Hair dyes are still more
poisonous. They never make the hair look natural,
and the lead which they often contain may poison the
I
A hair ( x 200) .
a epidermis of the skin.
b hair shaft.
c sebaceous or oil gland.
d muscle which makes the hair erect.
e epithelium of the hair root.
/ fat cells in the derma.
g papilla from which the hair grows.
108 APPLIED PHYSIOLOGY
body. The hair should be washed as often as it becomes
dirty.
202. Perspiratory glands. — In almost every part of the
skin there are little tubes made of cells of epithelium, like
those of the epidermis. Their lower ends are coiled into
a knot, and their outer ends open upon the surface of the
epidermis. Each tube is a perspiratory gland. The cells
of each gland make 'the sweat or perspiration. The
perspiration is being given off all the time, and dries as
fast as it forms. But if we are too warm, it is given off in
such amounts that it collects in drops. About a quart is
produced every day, and much more on a hot day.
203. The perspiration. — The perspiration is nearly all
water. A little mineral matter and some oxidized waste
matter are dissolved in it. You have already learned that
the perspiration takes away the extra heat when we are
too warm. This is the main use of the perspiration. It
also takes away some waste matters of the body.
^204. The waste of the body. — We will now study how
these waste matters are given off. All oxidation within
the body produces carbonic acid gas and water. The car-
bonic acid gas is of no use in the body, but passes off as
waste through the lungs. A great deal of water must pass
off from the body, so as to wash away the waste matter.
Water is found in everything which the body gives off.
The oxidation of albumin produces, in addition to the
water and carbonic acid gas, another substance which we
call urea. Urea is a poisonous waste substance, and must
be removed as fast as it is formed. If oxidation is incom-
plete from lack of oxygen or other causes, other substances
like urea are formed. Many of these substances are ex-
tremely poisonous. Urea and all substances like it are
given off by the perspiratory glands, and also by another
THE SKIN AND KIDNEYS 109
set of tubes called the kidneys. The waste mineral matter
of the body also passes off by the skin and kidneys.
205. The kidneys. — The kidneys are two bean-shaped
bodies, lying one on each side of the backbone, underneath
the lowest ribs. Each kidney is made of coils of very fine
tubes lined with epithelial cells. These cells separate
the urea, mineral matters, and water from the blood,
and pour the whole into a single tube which goes to the
bladder.
206. Urea in the perspiration. — The perspiratory glands
of the skin also separate urea, mineral matter, and water
from the blood. The kidneys get rid of many times as
much urea and mineral matters as the skin, but the skin
gives off nearly as much water as the kidneys. Some-
times the kidneys get diseased, so that they cannot get rid
of the urea. Then the whole body is poisoned, and the
kind of disease called Brighfs disease comes on. Then
the skin may give off much more than its natural amount
of urea, until the kidneys are able to do their work again.
207. Need of bathing. — The water of perspiration dries
off from the skin and leaves the urea and mineral matters
behind. The outside of the epithelium becomes dead, and
part is worn off, and part stays upon the skin. All kinds
of dust and dirt also stick to the skin, and stop its glands
so that the waste matters cannot pass off as they should.
So the skin needs to be bathed, Owing to the oil in the
skin, water alone will not always remove the dirt, and so
plenty of soap is needed. When there is an unpleasant
odor about the skin, it certainly needs a bath.
In summer, when we perspire and the air is full of dust,
we need a bath more often than in winter. It does not
matter how the bath is taken, so long as we wash well.
We can get clean by using a common basin. Bathing the
HO APPLIED PHYSIOLOGY
whole body every week in winter and two or three times a
week in summer will keep most persons clean.
208. Too much washing. — Some persons soak them-
selves in hot water and rub the skin for a long while.
Soaking in hot water loosens and kills the epidermis, and
then by rubbing, it can be made into little rolls. These
rolls are not dirt, but are the epithelium, which is a coat to
keep us warm and to keep the deeper parts of the skin
from being hurt. We can rub this epithelium off as long
as any is left.
209. Cold baths. — A cold bath drives the blood away
from the skin at first, but in a moment it comes back, and
we feel warm again. The heart beats with greater vigor,
and we feel refreshed by the bath. If we stay in too long,
the blood does not come back to the skin and we feel cold
and weak. A cold bath every morning upon first getting
up makes us feel warm and refreshed. But a weak per-
son cannot stand a cold bath. No one should stay in the
water after he begins to feel cold.
210. Hot baths. — A hot bath causes more blood to flow
through the skin, but does not make the heart stronger.
Less blood passes through the brain and deeper parts of
the body, and we feel weak and sleepy. Often we feel
cold after it. The best time to take a hot bath is when
we are going to bed.
211. A fair skin. — Bathing keeps the skin fair and
smooth, but neither bathing nor anything else will make it
fair if the waste matters which circulate in the blood are
not given off in the right way. The best way to keep the
skin fair is to arrange our food and habits so that there is
only a small amount of waste matter to be given off. If
we eat only plain food, slowly, and at mealtimes, and in
the right amounts, our food will digest as it should, and
THE SKIN AND KIDNEYS III
will be taken into the blood and be oxidized in the right
way. Then the kidneys and skin will always do their work
well. This is why you are so often told that you must
keep your stomach in good order if you wish to have a
fair skin. Paint and powder are merely a kind of dirt;
they stop the action of the skin, and only make it look
worse than ever.
*v212. Washing clothes. — The waste matters of the skin
are rubbed off upon our clothes and bedclothes. These
become dirty and must be washed. Air and the sun have
great power of destroying waste matters of the body. At
night all our clothes should be taken off and put where the
air can get at them, and we should sleep in a clean night
dress. In the daytime our beds should be aired, and the
clothes and blinds opened so that the sunlight can reach
the room and destroy the waste matter.
The water and waste matters of the body, and the water
used in washing and bathing, all contain poisonous matter.
If it is thrown upon the ground it may soak into the well
and poison the drinking water, or its gases' may make the
air unfit for breathing. The water used by a person who
has a catching disease is very dangerous, for the germs of
the disease can grow outside the body and cause the dis-
ease in the next person who gets the germs. All water
and slops ought to be carried away from the house and
emptied into a deep hole in the ground. Then the soil
will soon kill all the poisonous germs.
213. What to do with slops. — Small families in the
country often throw their slops out of the back door, but
it is not safe to do this, for some may run into the well and
poison the water. A well ought to be dug on ground higher
than the kitchen and barn. Hard rock or clay sloping
toward the well may carry slops underground into the well
112 APPLIED PHYSIOLOGY
(see page 32). It is as dangerous to use such impure water
for washing as for drinking. In cities the slops are carried
away in pipes called sewers. They empty into the rivers
or into the sea, and their waste matters are washed away.
Sewers give off a foul gas, and great care is needed to
prevent its getting into our houses.
214. Effects of alcohol upon the kidneys. — From the
time alcohol is swallowed it causes more waste matters to
be formed. It hinders digestion, so that the food does not
reach the liver in the right form. The liver is overworked
in changing the food to blood, and lets some through half
changed, and even lets poisons pass through. Then, in
the liver, alcohol appropriates oxygen and the food is not
properly oxidized, but still more poisons are made. The
kidneys and skin try to get rid of these poisons, and may
do it for a long while, but they become overworked and
finally fail, and then Bright's disease comes on. Alcohol
makes more kidney trouble than all other causes put to-
gether ; in fact, it is almost impossible to drink for a long
time without bringing on kidney disease.
215. Alcohol and the skin. — Alcohol causes an increased
flow of blood through the skin, making it redder than
usual. After a few weeks of drinking, the skin and eyes
remain red continuously, and their cells do not receive
proper nourishment from the blood. These effects are
seen upon the face more than anywhere else. Its skin
is often rough or spotted, or covered with pimples. Often
the nose becomes thicker and larger. All these things
give the skin a very unpleasant appearance, but they indi-
cate the condition of the whole body. A skin which is
weakened by alcohol cannot do the work of the kidneys,
and kidney disease in drinkers is much harder to cure
than in those whose skins are in good order.
THE SKIN AND KIDNEYS I I 3
SUMMARY
1. The skin is made of a thick, tough part called the
derma, and a thin protective covering of epithelium
called the epidermis.
2. The derma contains blood tubes, nerves, and perspira-
tory glands.
3. The epidermis protects the derma and forms the nails
and hair.
4. Oxidation of albumin makes a substance called urea,
which must be given off from the body. Urea and
carbonic acid gas are the main waste substances of
the body.
5. The kidneys and perspiratory glands are coils of fine
tubes, made of epithelial cells, which take water,
urea, and mineral matters from the blood.
6. We must bathe our bodies and wash our clothes so
as to wash away the waste matters from the skin.
7. Slops must be carried away from the house so that the
poisonous matter will neither get into the well nor
make foul gases.
8. Alcohol causes poisons to be formed in the body which
the kidneys try to throw off, but they become over-
worked and diseased in the attempt.
9. Alcohol weakens the skin so it cannot help the kidneys
get rid of the waste matter. It also gives the skin
an unpleasant appearance.
OV. PHYSIOL. (INTER.) — 8
CHAPTER XII
THE NERVES AND SPINAL CORD
216. Cells act together. — We have seen that the cells
of the body eat and breathe, and that oxygen burns
their food and bodies, produces heat, and gives them
power for their work. Each cell is thus a complete ani-
mal, like the ameba. But millions of amebas tied together
in the shape of the body would not act like a man, for
no two would act together, but they would fight and strive
to get away from each other. The cells of the body are
tied together by strings of connective tissue. But they are
well-trained servants, and all obey the mind. They work
so well together that we do not think of our bodies being
made of separate cells.
217. Nerves. — The mind lives in a few cells and rules
all the rest. From these cells, little threads called nerves
A nerve taread (X 400).
a central conducting fiber. b covering of fat.
go to every part of the body and touch every cell. The
mind and the cells talk to each other over these threads,
just as you can talk to a friend over the telephone. A
nerve thread is like a very fine wire covered with a kind
of fat. It is so small that a microscope is needed to see it.
Many of these threads run together in bundles, which we
114
THE NERVES AND SPINAL CORD
115
A thin slice from the end of a cut
nerve ( x 200) .
a nerve thread.
b connective tissue binding the
threads into a cord.
call nerves. In the upper part of the arm or leg they are
as large as a knitting needle, and grow smaller as threads
are given off to the cells. There
are more of these nerves in the
skin than in any other part of
the body, but yet a thread
reaches every cell of the body.
218. Motor nerve messages.
— Nerves can carry messages
both from the mind to the cells,
and from the cells to the mind.
The mind sends messages to
the cells for each to do its own
kind of work. Thus it tells the
muscle cells to move the arm
or leg. It tells the salivary glands to make saliva and
pour it into the mouth. It tells the liver cells to change
digested food to blood.
The mind also tells every cell in the body how much to
eat, and how much oxygen to breathe. The cells can eat
and breathe without being told by the mind, but if the
nerves do not bring the messages from the brain, the cells
do as they please about eating, and sometimes get lazy and
hardly eat or breathe at all, but waste away as in a para-
lyzed man.
Nerves which carry messages from the brain to the cells
are called motor nerves, for orders to move or change in
shape are often sent to the cells. These messages are
continually coming and going, and when they stop, life
ends at once.
219. Sensory nerve messages. — The cells of the body
also send messages of their state and needs. They send
messages to the mind whenever anything touches them.
Il6 APPLIED PHYSIOLOGY
The message to the mind is called a feeling or sensation.
The cells send such true news of everything which they
touch that the mind depends upon it wholly for news of
the outer world, and is seldom deceived. When something
touches the cells so as to hurt them, the mind feels the
message as a pain. Then the mind tells the muscle cells
to pull the cells away from the thing which hurts them.
Pain is a good thing, for it not only tells us when we are
being harmed, but it also makes us get away from danger.
The cells of the body also send word when they are
hungry or thirsty. This is different from the hunger and
thirst which we feel in the mouth, and which is only the
message of the stomach that it is empty. Each cell of
the body calls for food, and the mind supplies it by causing
the arteries to become larger so as to supply them with
more blood. Each cell also sends word to the mind when
it is tired and needs rest.
A nerve which carries messages to the brain is called a
sensory nerve, because we feel many of the messages. We
do not feel the message as it passes over the nerve, but
only when it reaches the mind in the brain.
-££20. False messages. — Sometimes false messages are
sent. If a nerve is pinched or hurt in its course, the mind
feels the message as if it came from the end of the nerve.
When we pinch the nerve which makes the funny bone in
the elbow, it seems to the mind that the little finger is hurt.
When the nerves at the knee are squeezed, as when you
sit with your legs crossed for some time, they cannot carry
the messages from the foot, and so we say that the foot is
asleep.
When the surgeon cuts your flesh, you feel great pain.
So he puts a little cocaine upon the nerve through a hollow
needle, The cocaine keeps the nerves from sending the
THE NERVES AND SPINAL CORD
17
news of the cut to the brain, and you do not feel pain
when you are cut. In a little while the blood washes away
the cocaine, and you can feel again.
221. How fast nerve messages travel. — The nerves can
carry messages about one hundred feet each second, or a
little faster than an express train. In the time between
two ticks of a watch, news of a pin prick can travel from
the foot to the brain, and the mind can send word back
for the muscles to move the foot away from the pin. If
your arm were long enough to touch the sun, you would
die of old age before the feeling of the burn could reach
you.
.- 222. The spinal cord. — As we follow the nerves back-
ward, we can trace them into the inside of the backbone,
where they seem to come
from a white string of
flesh called the spinal
cord.
The spinal cord is a
soft cord about eighteen
inches long, and about
the size of the end of
the little finger. It is
hung in the middle of
the rings of bone which
make up the backbone.
When it is cut across, its end looks like a white ring
around a gray, butterfly-shaped center. In the gray
matter are cells in which a part of the mind lives. The
white matter is made of nerve threads like those in the
body. Some stop at the cells of the spinal cord ; others
go on to the brain ; and still others start at the cells of the
cord and end in the brain.
A thin slice from the spinal cord with the
cells and nerves magnified 200 diameters.
a cells in the gray matter.
b fibers in the gray matter.
c nerve threads in the white matter.
n8
APPLIED PHYSIOLOGY
223. How the spinal cord acts. — The mind in the cells
of the spinal cord is like a telegraph operator, who does
not send messages except as others tell him to. In the
first place, the mind in the brain sends all its orders
through its servants, the cells of the spinal cord. When
it wishes to move the hand, it sends word to the cells of the
spinal cord, and they send word to the muscles of the arm
so quickly that we do not know that they had anything to
do with moving the arm.
224. Reflex acts. — In the second place, the spinal cord
sends orders when asked to do so by the cells of the body.
a tack pricking the hand.
d motor nerve.
Diagram of reflex action.
b sensory nerve. c nerve cell in the spinal cord.
e muscle moving the hand away from the tack.
The nerves which carry the messages from the cells of the
body go to the cells of the spinal cord, and also to the
brain. The cells of the spinal cord are much nearer
the cells of the body than the brain is, and when they get
word that anything has harmed a part of the body, they
have the power to order the muscles to snatch that part
away without waiting for word from the brain. Thus, when
the cord receives word that the hand touches a hot stove,
it at once sends an order for the muscles to snatch the
hand away, and it is done by the time the brain feels
the burn. When anything suddenly hurts you, you cannot
THE NERVES AND SPINAL CORD
19
help jumping away. This is called a reflex act, because
the pain seems to be reflected back as motion.
225. Orders for the growth of cells. — The spinal cord
also sends most of the orders for the cells to eat and grow,
and for the glands to work, and for the arteries to become
large or small, as each part of the body has need of blood.
These are nearly all reflex acts. When the cells of the
stomach feel food touching them, they tell the spinal cord,
and it sends word to the glands to pour out gastric juice.
226. The sympathetic nervous system. — The spinal cord
sends its orders for the growth of cells, for digestion, and
for the flow of blood through a minor set of nerve cells
and fibers. There are several small collections of nerve
cells arranged mostly in a double row down the front of
the backbone. Each collection looks like a grain of wheat
and is called a ganglion. From the ganglia fine nerves
go to the different arteries and glands, and to the stomach
and intestine. The ganglia are also connected with the
spinal cord and derive most of their power from it. They
are really its servants, just as the cord itself is the servant
of the brain. The ganglia and nerves are called the sym-
pathetic system.
The sympathetic system sends its orders slowly and regu-
larly. It has but little sensation, and is but slightly affected
by outside influences. So ordinary causes will not disturb
digestion or the flow of blood.
227. Acquired reflex acts. — In order that the brain may
be able to do more work, it is continually teaching the
spinal cord how to send the proper messages alone. When
a baby first learns to walk, its brain has to tell the spinal
cord just how far to order the feet to be moved, and when
and in what direction. So it is hard and slow work for
the baby to walk, but in a little while the spinal cord learns
120 APPLIED PHYSIOLOGY
to send the orders alone, and thus walking becomes a reflex
act. So in learning any new motion, after we have done
it a few times" our spinal cords send the proper order with-
out our thinking of it.
228. Need of the spinal cord. — The spinal cord acts
without our knowledge. We do not feel the cells of the
body grow, and we do not feel the spinal cord send the
orders for their growth. It controls all the vital actions
of life. It is well we do not have to think about sending
the orders for living, for we might forget them and then
we should die. As it is, the cord attends to them wholly
without our knowledge. We put food into our stomachs
and the spinal cord sees that it is made into living cells
and that the cells do their work. We cannot change its
work by any amount of thought or effort. An animal's
spinal cord does its work as well as a man's. In fact, it
has the same kind of work to do and is as perfect as man's.
SUMMARY
1. Nerves carry messages from the mind to the cells of
the body, telling them to act and to eat. The cells
also send messages to the mind, telling of their needs
and of what is touching them.
2. Nerves begin in the spinal cord.
3. The spinal cord is itself made of nerve threads, and
also of cells in which a part of the mind lives.
4. The nerve cells of the spinal cord send messages over
the nerves when told by the mind in the brain.
5. The cells of the spinal cord also send orders in response
to information brought by the nerves. This is called
a reflex action. Orders to grow and to snatch the
body from a sudden danger are reflex acts.
THE NERVES AND SPINAL CORD 121
6. In sending orders for the preparation of food and the
growth of cells, the spinal cord acts through another
set of nerve cells and fibers called the sympathetic
system.
7. The sympathetic system sends fine nerves to the mus-
cles of the arteries and of the intestine. It acts
under the control of the spinal cord.
CHAPTER XIII
THE BRAIN
229. The brain. — The mind, which is the real man, and
which feels, thinks, and makes our bodies move, lives in
the brain. The brain lies in the top of the head and is
covered with the bones of the skull. It is a soft, white
mass weighing about three pounds.
230. The medulla. — The brain is made of three main
parts. Just above the spinal cord is a small, wedge-shaped
part called the medulla
oblongata. The medulla
is a part of the spinal
cord as well as of the
brain. It gives off nerves
to the head just as the
spinal cord gives them
to the rest of the body.
In it is a little bundle of
nerve cells which send
out the orders for the
body to breathe. When
these cells are hurt, breathing stops at once and the body
dies. So the medulla is often said to be the seat of life.
231. The cerebellum. — Above the medulla is a round
part of the brain called the cerebellum. It neither sends
orders nor feels, but in some unknown way it helps the
rest of the brain so that they send out better orders for
Human brain cut crosswise.
THE BRAIN
23
walking and standing upright, and for all motions in which
the body must make exact movements. A bird or dog
without its cerebellum cannot run or stand, but flutters or
rolls about the floor. Yet it is strong and acts all right
in other ways.
232. The cerebrum. — The uppermost part of the brain
is the cerebrum. It is about four times as large as all the
Ifiegion
Regions of the head and action of the different parts
of the brain.
rest together. Its inside is 'white matter and is made of
nerve threads. Over the white matter is a covering of
gray matter which looks as if it were too large and so is
folded and puckered. The gray matter has many nerve
cells. The mind lives in these nerve cells. The nerves
of the white matter join these cells and connect them with
the spinal cord and with the nerves of the body.
124 APPLIED PHYSIOLOGY
»<&33. The senses. — The cells of the body are continually
sending news of their own state to the spinal cord. The
brain feels the news only when it is very great in amount,
as when the body is hungry or thirsty or tired.
The cells also send messages telling what is affecting
them from the outside. This news goes to the brain and
produces a feeling, while it only slightly affects the spinal
cord. We get news of the outside world by means of see-
ing, hearing, feeling, smelling, and tasting. These five
kinds of news are called the senses.
234. Location of the senses. — Feelings of sight are
brought to the cells of the brain under the lower and back
part of the head. Messages of sound, smell, and taste
reach the mind in the cells just above the ears. We feel
a touch or pain by means of the cells under the top part
of the head. This means that if the back part of the brain
is injured, we can no longer see. In the same way, an
injury to any part of the brain deprives us of the sense
which is located there.
235. Motion. — Besides feeling, we can also move our
bodies as we wish. The orders for moving are sent from
the brain down the spinal cord, and out along the nerves,
to the muscles. They cause the muscles to move the
body. That part of the brain under the top of the head
in front of the ears sends the orders for motion. If this
part of the brain is hurt, we cannot move so much as a
finger, even if we can feel and have a full knowledge of
what touches it. Each muscle has its own set of cells in
the brain. These do the same things in both man and
animals.
236. Memory. — When a cell of the brain receives a
message, it lays it away so that it can find it again. A
message stored away for use is a memory. We remember
THE BRAIN
125
how pleased we felt when we heard the band play, and
how our ears ached when we were out in the blizzard.
We can also remember the messages which the brain has
sent out. Thus we remember how hard we had to run to
catch the train, and that we had to make our arms move
in a certain way in order to throw a stone against a mark.
237. Association of cells. — Each cell in the brain is con-
nected with all the other cells through the nerve threads
of the white matter. So when we remember one thing we
at once think of something else about it. Thus one set
remembers that it saw a field of large ripe blackberries ;
another set of cells remembers how good these tasted ;
another set remembers hearing a dog make a great noise;
and still another set of cells remembers how fast it made
the legs run to take the body away from the berries.
238. Thinking. — The minds of all animals can feel as
well as a man's mind, or better, and can often make their
bodies move more swiftly and more gracefully than man's.
But the mind can do more than feel and cause the body
to move. It can think about what it remembers. It thinks
that some things were right and some wrong, or that we
could have done better if we had acted in a different way.
It plans to do things better next time. An animal does
very little thinking; so we say that it has no mind. It
seldom plans ahead and does not learn new things easily.
Yet some dogs and horses use almost as much thought as
some men.
239. Where thinking is done. — Thinking is done by the
cells of the brain behind the forehead. Animals have
very small foreheads, and so their minds cannot think to
any extent. While most of the cells of the brain can act
from the time a child is born, the thinking cells must be
taught how to act. Boys and girls go to school so as to
126 APPLIED PHYSIOLOGY
teach the cells of the forehead how to think. The cells
of the rest of the brain may know how to feel and see
and hear, and how to make the body move, and may have
wonderful things stored in memory, but if the forehead
cells do not know how to think, the mind cannot make
use of the memories. We say that such a person is a
fool, even though he has great knowledge. In school it
is of little account how many things are stored away in
the memory, for we can get memories anywhere. But in
school we should learn how to use memories, and how to
tell which ones are best and right for the work we wish
to do.
.•240. How to think. — The only way to teach the cells
under the forehead is to make them work at one thing at
a time until they can do it. When a boy wants to get his
lesson upon the reason for the temperature at the North
Pole, he cannot do it if he thinks a minute of the North
Pole, and then a minute about snowballing, and then
another minute of baseball, and then goes at the North
Pole again. But this is the way boys and girls naturally
do, and only a few succeed in training their foreheads to
think of one thing at a time. To learn to think well re-
quires great effort, kept up for a long time. A man is
educated when he can use all the power of his mind in
thinking of one thing at a time. If a boy thinks of kites
when he is studying geography, he must get back to his
geography as quickly as he can. He will like his kites
all the more when he gets his lesson, for he will be more
likely to put his whole mind upon them.
241. Speech. — The highest act of the mind is speech.
The lips and tongue can be moved when ordered by the
brain cells above the ears, but if they move so as to pro-
duce speech, the orders must be sent by a special set of
THE BRAIN 12?
nerves in the lower part of the brain just above and in
front of the left ear. When this part of the brain is de-
stroyed, a person cannot talk, but he can still make a noise
with his mouth and understand speech, for the hearing
part of his brain is whole. He can also read and write,
for these parts of his brain are also whole.
242. Use of speech. — The power of speech accounts for
the great difference between man and animals. Animals
must learn everything through their senses. They can-
not tell one another how to do certain things. They
cannot tell their knowledge to their young.
Men know far more things than they have learned by
their senses, for they can tell each other. In a short time
the father can tell his child what it has taken him a life-
time to learn. Children of ten years of age now know
much more about some things than men used to know a
hundred years ago. Some persons cannot see or hear or
speak. They learn with great difficulty, but finally they
can be taught to read with their fingers and then they
learn as rapidly as others.
243. Need of a healthy body. — Thinking is work, just
as running or any other action of the cells of the body is
work. In order to think, the cells must get plenty of food
and oxygen. The cells of the brain are the first to suffer
when food does not digest or the air is foul. A headache
and dull feelings are the first signs that something is wrong
with the food or air. Anything that makes food digest
better, or that causes us to breathe in more oxygen, helps
the brain. Plenty of out of door exercise is a great help
to the scholar. The best student generally has a strong
body.
^244. Sleep. — The brain cells work and become tired
like any other part of the body. They need rest. Some
128 APPLIED PHYSIOLOGY
must keep acting all the time. The spinal cord must keep
sending orders to the cells to eat and grow, and the me-
dulla must send orders for us to keep breathing. But they
send an order and rest a second, and then send another.
Like the heart, they rest half the time.
When the thought cells rest, we do not know anything,
but are asleep. During sleep they regain strength and
grow like a resting muscle.
245. Worry. — We can do a great amount of hard brain-
work if we can only sleep. It is doubtful if any one can
overwork the brain if he gets rest in sleep. He cannot
help sleeping when his brain gets tired, and when he
wakes he will be ready for work again. But sometimes
a person is troubled. This keeps his mind in action just
enough to prevent his resting. Then he feels tired, even
if he does not work, for he gets no rest.
246. How much sleep ? — A child needs at least ten
hours of sleep each day up to the age of twelve years. By
the time he is eighteen, he needs only eight hours. By
the time he is thirty, six or seven hours of good sleep will
be enough. When he becomes old and feeble, he will need
more again.
The time of sleeping is of less importance than that this
time should be regular. A short nap in the middle of the
day is very helpful.
247. Habit. — When the cells of the brain have done a
thing a few times, they want to do it again, and will often
act without our knowledge. So we can form a habit of
doing a thing. All of us have habits, and are forming
new ones. We may swear, or drink, or be dishonest once
or twice, and not be so again. But if the temptation comes
again we shall yield more easily for having yielded once,
and after a few times we shall yield even if we do not
THE BRAIN
129
want to. Many men swear when they do not know they
are doing it. They have acquired the habit, and find it
very hard to stop. We should be very careful how we
begin to do a wrong thing, for no matter how strong a
mind we have, we may fall into the habit of doing the
thing.
248. Good habits. — We can also form good habits. If
a boy is brought up to be generous and to speak kindly,
he will find it easy to do so all his life. He will not think
that giving means a loss to himself, but he will find as
much pleasure in the joy of others as in his own happiness.
We ought to form habits of doing good deeds and saying
kind words. Then we shall be of benefit to all around us,
and shall become useful and noble men and women.
249. Heredity. — Our habits affect others besides our-
selves and our neighbors. They may become transmitted
to our children. This transmission is called heredity. The
son of a drunkard will be likely to drink, and the son of a
thief to steal. The tendency is born in them. To get rid
of it, such boys must be taught good habits from their
babyhood. If they yield once, their tendency to form
the bad habits of their fathers will be stronger than their
tendency toward the good.
250. Nervousness. — A man's feelings often lead him
to desire things which his thoughts tell him are wrong.
Sometimes his feelings are made very unpleasant by little
things which his reason tells him he should not mind. In
all persons there is a conflict between thought and feeling.
Man differs from the lower animals in that he puts aside
his present feelings so that he may get more good in the
future. Reason must often overrule the feelings, to deny
them a pleasure or to compel them to endure an annoy-
ance. A lack of self-control is nervousness.
OV. PHYSIOL. (INTER.) — 9
130 APPLIED PHYSIOLOGY
Nervous persons are made uncomfortable by slight
noises, or by little pains, or by being denied something
that they want. They complain, and go about with sad
and troubled faces, like spoiled children. They make
more fuss over a slight thing than they would over the
loss of a dear friend. They are generally afraid that
something is going to happen.
Nervousness is to a great extent a habit. By an effort
of thought any one can overcome nervousness. It is the
duty of every one to do this. You should not laugh at a
nervous person, but should encourage him in every way to
become as brave as yourself.
251. Fear. — An extreme degree of nervousness over
any one thing is fear. The great danger in fear is that a
person may not think of what he is about. Then instead
of escaping from danger he may rush into it. When a
crowd is in danger, as in a burning building, all are liable
to rush in' one direction and to trample upon each other
as they try to escape. Then a cool head is needed. Do
not follow the crowd, for it is more dangerous than the
fire. Remain quietly until you can get out without going
in the crowd. You will be safer, and besides you will do
a great deal towards making others in the crowd think
of what they are doing.
252. Fire drills in schools. — In large school buildings,
the children are trained to drop all work at the sound of
a bell and to march quickly from the building. The bell
is the fire alarm. It is sounded every day or two when
the children are not expecting it. They do not know
whether it is sounding a real alarm or not. When a fire
really occurs, they will march out of the building as
orderly as in the drill. The drill is a good training in
bravery and self-possession.
THE BRAIN
131
253. Dreams. — When the brain is asleep, a few sets of
cells may recall memories so vividly that they seem real.
This is a dream. A dream is not an indication of what
is to take place, but is only the shadow of what has
already been done.
254. What the mind is. — No one has ever been able
to find out what mind is. It is not the cells of the brain,
for some of them have been destroyed in men, and yet
the men have retained perfect minds. It seems to be the
soul, or spirit of men, which lives in the cells and causes
them to work for it. We believe that the mind, or soul
of man, lives on after the cells in which it dwells are dead.
SUMMARY
1. The medulla oblongata acts for the head as the spinal
cord does for the body. It also makes and sends
out the orders for breathing.
2. The cerebellum gives us the power of balancing our-
selves and of making exact movements.
3. The cerebrum is made of nerve cells covering a central
mass of nerve threads.
4. The mind lives in the nerve cells of the cerebrum, and
sends its orders out over its nerve threads.
5. The mind feels with the back and lower parts of the
sides of the brain.
6. The mind sends orders for movements from the cells
upon the top of the sides of the head.
7. The mind thinks with the cells behind the forehead.
8. By means of the nerve threads, the mind in the brain
cells can talk with every cell of the body.
9. The mind is the spirit of man which, we think, lives
on, even after its home, the body, dies.
CHAPTER XIV
NARCOTICS AND THE NERVOUS SYSTEM
255. How alcohol affects the mind. — Alcohol may
weaken any part of the body, but this is of minor impor-
tance compared with its liability to ruin the mind and
character of men. If alcohol is swallowed, but little can
be found anywhere in the body at the end of an hour.
But in its destruction it causes the albumin of the body to
give rise to poisonous substances, which circulate every-
where among the cells. These poisons are probably what
affect the nervous system of drinkers. .
256. Alcohol and the spinal cord. — Because alcohol at
first makes the heart beat stronger, it drives more blood
through the spinal cord. This makes the nerve cells act
more quickly, so that a person is bright and active, and
feels as though he were stronger and more skillful than
usual. He is ready to try foolish things and dangerous
acts in order to show his skill. He notices every sound
and movement and jumps at slight noises which do not
usually annoy him. So he says he feels nervous and he
takes more drink to quiet his nervousness.. Finally he
gets enough alcohol to weaken his cells so that they cannot
notice anything, or send proper orders to feed the cells.
Then he is dead drunk, and is in danger of his life.
257. Alcohol and thought. — Alcohol affects the brain in
much the same way that it does the spinal cord. At first
the blood flows more rapidly and makes the brain more
active. A drinker is full of thoughts and is talkative,, but
i32
NARCOTICS AND THE NERVOUS SYSTEM 133
his words are mostly memories, and his thought cells in the
forehead do very little new work. When alcohol begins to
appropriate oxygen belonging to the body, the brain cells
are the first to suffer. Those cells of the brain which do
the highest kind of work suffer first. The thought cells in
the forehead are the first to be weakened. The highest
kind of work which they do is to make a person think of
the feelings of others before his own. Drink makes a man
selfish and he cares less for others' feelings and for what
they think of him. He does not care if his clothes and
face are dirty and if he is disagreeable to others. He is
easily made angry and often wants to fight over small
matters.
The next actions to be affected are thoughts of right and
wrong. He steals without reason, and may commit murder.
Many a criminal has made himself half drunk so that he
could commit the crime from which he shrunk when sober.
Finally, all the cells under the forehead are weakened
and the man cannot think at all. He does not think what
might be the result of his acts, but is as likely to throw a
lighted match into a pile of paper as into the stove. Many
accidents and fires are due to the lack of thought of drink-
ing men.
258. Alcohol and motion. — A person thus far under the
influence of drink is often very amusing in his talk. He
can still go about with a steady gait, but he cannot be
trusted to do business. If he stops drinking, the effects
will pass off in an hour or two. If he keeps on drinking,
the cells which cause movements of the muscles are next
affected. He cannot control his muscles, but walks with
an unsteady gait. His hands tremble and he talks thick.
He is now drunk.
y 259. Alcohol deadens feeling. — Next, the cells which
134 APPLIED PHYSIOLOGY
receive messages of feeling are weakened. Then the
drunkard does not feel pain so keenly as he should. He
gets injured without knowing it, and may fall and freeze
to death without suffering. Before the days of chloroform
surgeons used to make their patient drunk so that he should
not feel the pain of the operation.
Because alcohol partly deadens feeling, it takes away
the feeling of weariness, and the drunkard thinks that,
because he does not feel tired, the whisky has made him
strong. His mind is dulled ; he has not the sense to see
that he really has lost strength, and that his words and acts
are foolish. He judges by the feeling alone and keeps on
drinking, though each drink makes him still weaker and a
still greater fool. But the next day the effects of the
alcohol pass off and he feels a great weakness of his body
and brain, and needs a day or two in which to recover.
Yet in a little while there comes a desire to drink again.
So once started, the habit grows, for a person's good sense
is taken away, and he is too weak in mind to see the
results. -
260. Bad companions. — Another effect upon the mind
of the drinker comes from his being with other men in
the same state as himself. Their low stories and dirty
language and quarrels make decent men ashamed. No
person can hear them without being shocked. Yet men
become like those with whom they live, and so drinkers
learn to talk and think alike.
261. Light drinking. — A weakness of mind often comes
on, even if a drinker never gets drunk, and it is often in a
dangerous form. More insanity is caused by drinking than
by anything else, and slow, steady drinking causes more of
it than getting drunk and letting drink alone between times.
Besides those who are made insane, many are so weakened
NARCOTICS AND THE NERVOUS SYSTEM
135
in mind as to be incapable of attending to business. Many
a man has been compelled to give up his business because
he has been a steady drinker in such small amounts that
even his friends have not suspected him. His trouble is
really a beginning insanity.
262. Delirium tremens. — There is a disease called
delirium tremens which any drinker may get. Hard
drinking alone may cause it, but an injury may bring it on
in any drinker. Delirium tremens is a disease in which
the victim imagines that he sees all manner of foul animals
coming to torment him. The disease is one of the most
terrible known, and is very dangerous to life.
263. Heredity. — Another evil, even greater than the
others, is that the effects of drinking are handed down to
one's children. Nervousness and weakness of mind and
body often result. But worst of all, children often grow up
with a desire for drinking. Yet no person has the right to
drink because his father drank. It is within the power of
any person to abstain from drink, if he will.
264. Drinking a disease. — The drinking habit is a
disease of the mind. While a person should be punished
for the crimes he commits while drunk, he should not be
punished for drinking any more than an insane man should
be punished for being insane. Neither should you laugh
at the drinking habit any more than you should laugh at
any other kind of sickness. The friends of a drinker must
be the same comforters and helpers that they would be if
he were sick in any other way. He must be led to use his
will in putting away the habit. He should be made to
know that he is sick and unfit for work. When people
cease to be amused at drunkards and learn to treat them
as sick in mind, drinking will become unpopular, for men
do not like to be called sick. Fifty years ago men were
136 APPLIED PHYSIOLOGY
ashamed to say that they did not drink ; now men are
getting to be ashamed of drinking.
I /$65. Waste from alcohol. — In the United States alone
one and a half billions of dollars are paid for strong drink
each year. The drink is made from good fruit and grain
which can otherwise be used as food for man or animals.
Bread costs the people less than half as much as strong
drink. For every dollar spent for the support of churches
fifteen are spent for strong drink. To pay the drink bill
each year would take ten times more gold and silver than
is mined. The price of two or three drinks, if it were put
in a savings bank each day would amount to enough in ten
years to pay for a comfortable home.
The loss to the drinker is only a small part of the whole
loss. Because of sickness and loss of strength due to
strong drink the men who hire drinkers do not get the full
value for their money. In Great Britain it is calculated
that the amount of labor lost by drink would amount to at
least two hours every day for every workingman. The
loss is made much greater if we count the accidents to
property, health, and even to life caused by persons under
the influence of strong drink.
We must add to this estimate the amount spent on jails
and insane asylums, for over one half of all crime and in-
sanity is directly produced by strong drink. We must also
add the loss of great numbers of strong workers who once
filled high positions but have lost them because of strong
drink. We must also consider the loss of a far greater
number of young men who would have risen to be re-
spected citizens if it were not for strong drink.
To all this money waste we must add the amount of
suffering and want which the drinkers' families at home
must bear. We must also remember the number of chil-
NARCOTICS AND THE NERVOUS SYSTEM 137
dren who fall into bad habits from the lack of the good
example and restraint of their intemperate parents. The
money loss of strong drink can be restored, but the suffer-
ing can never be repaid. When all has been reckoned, it
will be found that strong drink is the cause of more waste
and evil than any other known thing. It affects every one
in the land, therefore it is right to make laws which shall
control the sale of liquor, or even stop its sale altogether.
266. Bitters. — There is a form of alcohol which many
use and do not know it. Strengthening bitters, Jamaica
ginger, and many tonics are simply strong alcohol with
flavors added. They produce the same stimulating effects
as whisky, and can easily make a person drunk. Their
effects are due to their alcohol. Some persons even have
a habit of their use just as men form a habit of using other
kinds of alcoholic drinks.
267. Drug habits. — Opium and chloral are sometimes
used to quiet the brain and to produce sleep. They are
dangerous drugs, for after their effects have passed off, the
brain feels worse than ever, and nothing but the same drug
will make it feel well again. So persons form habits of
their use. They quickly weaken the whole body, and affect
the brain more than any other part. Those who use the
drug seldom live more than a year or two. Many other
drugs will also lead to slavish habits of taking them, but
opium and chloral are the most common ones.
268. Headache powders. — There are a number of simi-
lar drugs made from coal tar which are used to relieve
headaches. Phenacetine is the most common one. Under
a doctor's direction they are valuable remedies ; but many
use them on their own responsibility, and finally find that
they do not feel well without the drug. All these drugs
weaken the heart and may produce violent poisoning.
&
138 APPLIED PHYSIOLOGY
269. Tea and coffee. — Many persons who use tea and
coffee do not feel well without them. They stimulate the
brain to greater exertion ; but when their use is stopped
the brain feels its weariness. Then another cup is needed,
and so a habit of their use is formed. They often produce
headaches and disordered stomachs, and so their habitual
use weakens the whole body, including the brain. They
often produce nervousness and sleeplessness. They should
be regarded as drugs and not as food. Young people
especially are easily harmed by their use.
270. Tobacco. — Men use tobacco to quiet their brains.
When they are alone they use it for company, to keep
from thinking, but when they are with others they use it
because the rest do. On the other hand, some men use
tobacco to make themselves think. Now, it cannot do
both of these things. In reality, it does not increase the
power of the brain, for it is a poison. Some men seem to
stand tobacco with but little harm, but no one can use it
and have the best brain.
271. Tobacco and drink. — Some people think that
tobacco quiets a person's brain when he has been drink-
ing. This is because tobacco lessens the overaction of
the brain which alcohol at first produces. On the other
hand, a little alcohol seems to make the tobacco user feel
stronger, and to relieve his thirst caused by tobacco. So
tobacco and alcohol naturally go together. A drinker
almost always uses tobacco, for its poison seems to relieve
the poison of alcohol ; but it only seems to do so, for in
reality it makes a person want more drink.
272. Waste from tobacco. — Like strong drink, the use
of tobacco is extremely wasteful. In the United States
half as much is spent for tobacco as for strong drink.
The land upon which it is grown is not only prevented
NARCOTICS AND THE NERVOUS SYSTEM 1 39
from bearing useful crops, but is also soon worn out so that
it will not produce any kind of a crop without large ex-
penses for fertilizers. Many fires are caused by the care-
less use of matches in lighting pipes and cigars. While
men often take strong drink because they may think it
may do them good, they chew and smoke only for their
pleasure. This tends to careless and wasteful habits of
living. A man is seldom so poor but that he will have a
smoke, even while his family may be compelled to live on
charity.
273. Chewing gum. — Chewing gum is made from pitch,
paraffin, and other thick and sticky substances which do
not dissolve in water. The gum itself has no effect, for it
is not dissolved and swallowed ; but the act of chewing it
causes a free flow of saliva when it is not needed, and
so there will be less formed during meals when it is neces-
sary for digestion. If gum from a dirty pocket is given to
another person it may carry disease germs. Beyond this,
chewing gum has little or no effect on the body. But its
use is uncleanly and is unpleasant to others. It seems
much like chewing tobacco, and refined persons avoid even
the appearance' of evil. Its use may encourage boys to
chew tobacco later in life.
274. Alcohol in cooking. — In raising bread by means of
yeast, alcohol is always formed, but the heat of the baking
drives it off, so that all trace of it is lost. In preparing
puddings, pies, and cakes, brandy or wine is often added
to give them flavor. If they are cooked afterward, the
heat will drive off the alcohol and so render the dessert
harmless. If it is not cooked afterward the alcohol re-
mains in the dessert and may do as much harm as if it
were taken in the form of the original brandy.
Even when all the alcohol is driven off from a dessert,
140 APPLIED PHYSIOLOGY
the flavor of the brandy or wine remains behind and may
teach persons to like the taste of the liquor itself. Chil-
dren who eat the dessert may grow up to like the taste of
the liquor even though they never drank a drop of the
liquor itself. In this way desserts flavored with liquor
may do much harm.
In bread, the alcohol has no special flavor, and so we
can eat bread without danger of learning to like the taste
of liquors.
275. Alcohol in confectionery. — Candies sometimes con-
tain brandy or whisky which is put in for their flavors.
One form of candy has a hollow center filled with brandy.
Children who buy the candy learn to like the taste of the
liquor. The sale of brandy or of any other form of liquor
in that way is a breaking of the law, for the candies contain
more brandy than many strong drinks.
276. Homemade wines. — It must not be supposed that
a wine is harmless because it has been made at home from
good grapes or blackberries, without adding any alcohol at
all. The alcohol in wine does not need to be put there, for
the fruit juice ferments and forms it. If any liquor fer-
ments at all it contains alcohol, and so is- a strong drink.
Homemade wines are often stronger in alcohol than many
bought wines.
277. Strong drink as a medicine. — It is a custom to give
some form of alcoholic stimulant whenever a person meets
with an accident, or is seized with a sudden illness. It is
doubtful whether it ever does much good at such a time.
On the other hand, it may be the very thing which ought
not to be given. For instance, if a person is bleeding, it
may cause the blood vessels to become larger and so lead
to a greater loss of blood.
Taking strong drink to break up a cold is liable to bring
NARCOTICS AND THE NERVOUS SYSTEM 141
on a greater cold by causing more blood to flow near the
surface of the skin, where its heat will readily be lost.
The greatest danger of all in the household use of strong
drink as a medicine is that children may grow up with the
idea that it is a good thing to use under almost all circum-
stances. Thus it tends to encourage them in its use. No
one can use an alcoholic drink with safety even as a medi-
cine unless he is directed by a physician.
278. Treating. — A harmful practice connected with
drinking is the custom of treating. Many a man would
not drink if he were not invited by a friend. Then he does
not dare to refuse either from fear of offending his friend
or of being laughed at. He may be led to take several
drinks against his will.
In Europe treating is seldom done. It would be much
better if Americans would not induce their friends to drink.
The custom and habit of treating is not confined to men
and women, but children learn it in treating each other to
candy. It is well to be generous, but it would be well to
do a person good instead of harm by your generosity.
279. Ether and chloroform. — Alcohol is used in the
manufacture of ether and chloroform. These two drugs
are used to produce a deep sleep in which operations can
be done on the body without giving pain. As soon as they
are breathed into the lungs they begin to stupefy a person,
but at first they also cause him to cry out and to toss him-
self about like a drunken man. In about five minutes he
is in a deep sleep and can be kept so for an hour or two
while the operation is being done.
When the ether or chloroform is stopped a person slowly
awakens and talks in a wandering way for some time. In
about half an hour he becomes wide awake again. The
condition of a man who is deeply under the influence of
142 APPLIED PHYSIOLOGY
strong drink resembles the condition of one who has taken
chloroform. But the effects of chloroform soon pass off,
while alcohol acts slowly, so that a person may die before
he can recover his senses.
SUMMARY
i. Alcohol interferes with the action of the nerves and,
spinal cord.
2. Alcohol overcomes the brain, first attacking its highest
acts.
3. When a man is coming under the influence of alcohol,
he first becomes selfish, and then careless. Then he
cannot control his movements, and next he cannot
feel. Finally he is dead drunk, and may die.
4. Continuous drinking, even if light, may overcome the
mind so that it becomes insane.
5. In some cases alcohol causes horrible dreams called
delirium tremens.
6. A drinker may transmit his mental weakness to his
children.
7. Drinking is a disease of the mind.
8. Tobacco weakens the brain, as it does all other parts
of the body.
CHAPTER XV
THE SENSES
A man knows what is going on around him in five ways.
He can feel, see, hear, smell, and taste.
280. Feeling. — ■ Nerves of feeling go to every part of
the body. Most of them end in the skin. When any-
thing touches them, they carry a message about it to the
upper part of the brain. These messages are of three
kinds : touch, pain, and temperature.
281. Touch. — When anything touches the body, but
does not harm it, the nerves carry a message simply of
touch. By means of this message the brain tells whether
the substance touched is hard or smooth, or round or
pointed, or has other qualities.
The tip of the tongue and the ends of the fingers are
very sensitive. The fingers can feel two pins distinctly
if they are only one twelfth of an inch apart, while the
back feels them as one if they are two inches apart. We
use the tips of the fingers if we wish to feel with accuracy.
By education, the sense of touch can be made very deli-
cate. Blind persons learn to do things by touch almost as
well as we do by sight.
282. Pain. — If anything touching the cells is harming
them, we no longer feel a touch, but only a pain. Then
we do not think whether the substance is hard, or smooth,
but only that it is doing us harm. So pain tells us if any-
thing is harming the body. A toothache shows that a
i43
144
APPLIED PHYSIOLOGY
tooth is decaying and needs filling. If we could not feel
pain, an arm or a leg might be burned or cut without our
knowing it.
283. Temperature. — We feel heat or cold by special
nerves in the skin. Draw a cold pencil point slowly over
the face. You feel its touch as it moves over your face,
but at a few points you feel only a coldness. These points
are scattered over the skin so close together that the whole
skin seems to feel the sensation. Whenever heat or cold
is great enough to harm the body, we feel only a pain.
a bone of the orbit.
b muscle which moves
the eyeball.
c sclerotic coat.
d choroid coat.
The human eye.
e retina.
f eyelid.
g iris.
h lens.
i cornea.
/ muscle which changes
the shape
lens.
k optic nerve.
of the
284. The eye. — The eye is a round white globe filled
with a clear fluid. In its front is a clear round window,
behind which is a muscular curtain called the iris. The
iris is blue or brown, and gives the color to the eye. In its
center is a round black hole called the pupil. The pupil
THE SENSES I45
can become larger or smaller so as to regulate the amount
of light which enters the eye. In a bright light it becomes
small and shuts out some of the rays. In a dim light it
becomes large, and admits all the light it can. Notice the
pupil of a cat's eye. In the middle of the day it is a
narrow slit, but in the evening it is almost round, and
admits more light than the pupil of a man's eye. A cat
can see well when it is so dark that we cannot see at all.
Behind the pupil is a clear body, shaped like two saucers
put together by their edges, or like a magnifying glass.
It is called a lens. A magnifying glass brings rays of
light together into one bright spot. The lens of the eye
brings together the rays from an object, and they form a
picture upon the nerves in the back part of the eyeball,
like a picture in a photographer's camera. The nerves
carry the impression of the picture to the back part of the
brain and so produce sight.
285. Movements of the eyes. —The eyes can be turned
in any direction we wish by means of muscles. Some-
times the eyes will not turn together, but while one looks
at one object, the other looks somewhere else, making the
person cross-eyed. A cross-eyed person usually sees with
only one eye. If the eye is treated before a child has
grown, it can be cured.
286. Coverings of the eyes. — The eyeball lies upon a
bed of fat in a bony case. It is covered in front by two
lids of flesh. These can be shut so as to protect the eye
from dust or injuries. Whenever anything is about to
enter the eye, it causes the lids to close so as to shut it
out. We cannot help winking when something is about
to strike the eye. When we are sleepy, we cannot keep
the lids from falling together.
Hairs grow from the edges of the lids. They curl
OV. PHYSIOL. (INTER.) — IO
146 APPLIED PHYSIOLOGY
away from the eyeball so as to catch whatever might fall
against the eye.
287. Dirt under the lids. — The front side of the eyeball
and the lining of the lids are very tender. If only a little
dirt gets under the eyelid, it gives great pain. Then the
eye should be kept still until the dirt can be taken out.
Rubbing grinds the dirt into the eye and makes it sore.
Never rub the eye when you think it has something in it.
Lift the lid by the eyelashes and the tears will usually
wash the dirt away. If they do not, let some one raise
the lid and pick out the dirt with a soft handkerchief.
288. Tears. — The eyeball is moistened with a saltish
liquid called tears. They are produced by a gland situated
just above and to the outside of the eye. They run over
the surface and down a small tube, and into the nose.
Winking rubs the liquid over the whole surface of the eye
so as to wash away dust. When you cry, the tears flow
faster than the tube can carry them into the nose. Then
some overflow upon the cheeks.
1 y 289. Care of the eyes. — Your eyes ought never to ache
■from use. If they do ache, you are straining them and
may do them great harm. You can use your eyes safely
until they begin to ache. At the first signs of discomfort,
you should stop work and give them a rest.
A bright light in front of the eyes is the most common
cause of eye strain. At night there should always be a
shade over the lamp, or else you should wear a shade over
your eyes. A cap will do for a shade if you cannot get
anything else.
The light should come from one side or over your
shoulder. Then it will not shine into your eyes. You
should never try to look at the sun. You should never try
to read by a dim or unsteady light.
THE SENSES 1 47
In a carriage or a railway car, your paper will shake,
and you must be continually moving your eyes to see. This
makes the eyes ache. You ought not to try to read under
these conditions.
When you read while lying down, you turn your eyes
in the direction of your feet, which is very tiresome.
290. Nearsightedness. — In order to see objects clearly,
some persons must hold them close to their eyes. This
is called nearsightedness. Nearsighted persons should
always wear spectacles. This will enable them to see as
well as any one.
291. Farsightedness. — As persons grow old, they can-
not see near by so well as afar off. This is called far-
sightedness. By wearing spectacles, they can see as well
as ever.
292. Alcohol and the eyes. — Alcohol causes the eyes
to look red, and may make them sore. In some cases
it causes the nerves of the eye to waste away. Then the
eye will be blind, although it will appear well.
In drunken persons the muscles of the eyes, like the
muscles of the legs, do not act rightly. They often turn
the eyes in different directions. Then the person will be
cross-eyed, and every object will seem double.
Tobacco, in some cases, causes the nerve of sight to waste
away. Tobacco smoke makes the eyes smart so that the
tears flow.
293. The ears. — We hear with our ears. Sound is
made by waves of air which beat upon special nerves.
The ear is a cavity, hollowed out of a very hard bone,
and is divided into three parts.
294. The outer ear. — The outer ear, which we see, is
not needed, but it does some good in catching the waves
of sound and throwing them into the tube in its center.
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APPLIED PHYSIOLOGY
This tube enters the skull. The tube and the ear which
we see are called the outer ear.
295. The middle ear. — At the end of the tube of the
outer ear a thin membrane is stretched like the head of
a drum. Beyond it is a hollow cavity which is like a
drum, and is called the middle ear. Air waves strike
a outer air passage.
b membrana tympani.
c malleus, or hammer bone.
d incus, or anvil bone.
e stapes, or stirrup bone.
Diagram of the ear.
/ semicircular canals.
g vestibule of inner ear.
h cochlea.
i Eustachian tube.
/ tympanum, or middle ear.
the drumhead and cause it to move rapidly back and
forth, just as a drumhead moves when it is struck. A
chain of three little bones stretches across the drum and
carries the movements of the drumhead to a third cavity
called the inner ear.
296. The inner ear. — The inner ear is made up of coiled
tubes. It is filled with a clear liquid into which the nerves
of hearing project. The movements of the little bones
produce waves in the liquid, which beat against the nerves.
Our brains feel the waves as a sound. The outer ear con-
ducts the sound to the middle ear. The middle ear acts
THE SENSES
149
#
Mke a sounding box to make it plainer and more distinct.
The inner ear is the real ear. Some animals, like fish,
have only an inner ear.
297. The Eustachian tube. — The middle ear is filled
with air. From it a tube, called the Eustachian tube, ex-
tends to the back part of the nose. When you blow your
nose hard, you can force air up the tube. This makes
your ears feel full, and you become partly deaf. When
you have a cold, the tube may become stopped, and then
your ear rings and feels as if you had blown air up the
tube. If it stays stopped, you may become deaf.
Sometimes a cold in the throat extends up the tube and
into the middle ear. Then you have an earache, and per-
haps your ear may discharge matter like that from your
throat. Throat trouble is the most common cause of ear-
ache and deafness in children. If a child breathes through
his mouth or has too large tonsils or anything growing
in the back part of his nose, he is very liable to have ear-
ache or deafness. So it is very important for you to have
your nose and throat in good order if you would have good
hearing. Scarlet fever often causes deafness, because the
inflammation of the throat extends up the tube to the ears.
298. Dull children. — Sometimes children get throat
trouble and earache before they can talk. Then they
grow up slightly deaf, but neither they, nor their parents,
nor their teachers know it. Such children cannot hear
well when spoken to, and so seem to be dull and careless.
Often they are punished for not attending to their work.
This is very unjust to the child. Every child that seems
inattentive or slow in obeying should have his hearing
tested. Hold a watch to his ear and see if he can hear
it as far away as you can.
299. Care of the ears. — Boxing the ears may burst the
150 APPLIED PHYSIOLOGY
drumhead, just as hitting a drum too hard may spoil it.
This may cause deafness. You should never strike a per-
son upon the ears in play. A very loud noise may also
burst the ear drum, or at least cause pain and deafness.
You should stop your ears when you expect a loud noise.
Men who shoot cannon often have to put cotton into their
ears before they fire.
Cold water in the ear may cause an earache. When
you get water in your ear while you are in swimming, turn
your head to one side and shake it so that the water will
run out.
Do not put anything into your ear. It is very hard to
get a bean or a stone out again. Cotton in the ear makes
the ear tender and causes more colds than it prevents.
If the ears run with matter, wash them out with clean
water and borax. Do not plug them up with cotton or
anything else, for that will keep the matter in.
300. Ear wax. — The outer tube of the ear produces a
kind of bitter wax. This keeps insects from crawling into
the ear. Sometimes it collects into a mass. By trying to
get it out you may force it farther into the ear and against
the drumhead. Then you will become partly deaf.
You should not pick your ears, for you may hurt the
drumhead. The wax naturally grows outward, and so does
not collect in the ear if it is left alone.
301. The nose. — We smell with the nose. In the upper
part of the nose fine nerves are spread out beneath the
epithelium. When a vapor in the air soaks through the
wet sides of the nose, it touches the nerves and produces
the sense of smell.
In order to have a smell, a substance must become a
vapor. So those substances which cannot become a vapor
have no smell. A very small amount of a substance in the
THE SENSES 151
air will excite the sense of smell. A tiny grain of musk
will continue to give out vapor and produce a smell for
years, and yet will not seem to diminish at all in size.
The outer wall of the nose.
a the nerve of smell at the base of the d curved curtains of bone.
brain. e opening of the Eustachian tube.
b air spaces in the skull bones. /soft palate.
c branches of the nerve of smell. g upper jawbone.
302. Use of smell. — Spoiled food and bad air each give
off a bad smell, while good food and good air always smell
good. The sense of smell guards us against bad air and
bad food.
When we have a cold in the nose we cannot smell. We
must keep from taking cold if we would have a good sense
of smell.
Alcohol and tobacco are irritating to the nose, and spoil
the sense of smell. Then the great safeguard against bad
air and bad food is taken away.
303. Taste. — The nerves of taste are situated mostly
152 APPLIED PHYSIOLOGY
upon the tongue. A substance dissolves in the saliva and
soaks through the epithelium of the tongue, and touching
the nerves produces the sense of taste. A substance that
will not dissolve in water has no taste.
The sense of taste tells us what food is good for us.
Unwholesome or spoiled food generally has a bad taste.
We can learn to like some things that are not good for us.
Tobacco does not taste good at first, but men learn to like
it. We never tire of the taste of wholesome food, but
when we get too much sweets or candy, their taste makes
us sick. Even if a thing tastes good at first, its taste may
afterward show it to be unwholesome.
We should not injure the nerves of taste by using
tobacco or alcohol. Even pepper and spices may injure
the taste so that we cannot tell when food is bad.
Sometimes the senses of smell and taste blend together.
If the sense of smell is lessened, as by a cold in the head,
coffee does not taste so good as it should. If the nose is
stopped, persons can scarcely recognize the taste of onions.
SUMMARY
1. Anything touching the nerves produces a feeling of
touch, or of pain or of temperature.
2. Touch tells us about the shape, hardness, smoothness,
and similar qualities of objects.
3. Pain tells us that something is harming the body.
4. Light passes into the eyeball and forms a picture upon
nerves, and thus produces the sense of sight.
5. Muscles turn the eye about, lids protect it, and tears
wash away dust from it.
6. Too bright a light harms the eyes.
7. Air waves pass into the tube of the outer ear, and are
carried across the middle ear by a chain of bones to
THE SENSES 1 53
nerves in the inner ear, where they produce the
sense of sound.
8. The Eustachian tube leads from the middle ear to the
back part of the nose. A cold in the head stops
the tube and causes earache and deafness. Most
earaches are caused by a cold in the throat.
9. Little particles in the air soak through the wet sides of
the nose and, touching the nerves beneath, produce
the sense of smell.
10. A substance soaking into the surface of the tongue
and touching its nerves excites the sense of taste.
1 1. Smell and taste guard us against bad air and bad food.
Bones of the
Clavicle, or Collar Bone
Sternum, or Breastbone
Pelvis, including (S.) Sacrum and
(Cx.) Coccyx.
Tibia, or Large Bone of Fore Leg
Tarsus, or Ankle and Heel Bones (7)
Bones of foot. — Nineteen bones.
Head and Face.
Bones of Vertebral Column.
Scapula, or Shoulder Bone.
Humerus.
Ulna.
Radius.
Carpus, or Wrist. — Eight
small bones.
Hand. — Nineteen bones.
Fibula, or small Splint Bone of Leg.
The Human Skeleton, showing position of bones.
154
CHAPTER XVI
BONES
304. Need of bones. — Besides eating, breathing, and
sleeping, man's body does a great deal of heavy work that
would crush a soft body. Man also goes from place to
place and carries heavy weights that he could not carry
if he did not possess something on purpose to move his
body. Inside the body is a stiff and strong frame of bone,
which is moved by muscles. Bones form the frame of
nearly every part of the body, while the muscles which
cover them make the body plump and round. About one
seventh of the body is bone, while over one half is muscle.
In all there are over two hundred bones in the body.
305. Shape of bones. — Long bones extend down the
arms and legs, and slender bones form the fingers and toes.
Flat, curved plates of bone form the skull. Rounded
bones form the wrists and ankles, and rings of bone form
the backbone. Bones are of different shapes in order to
fit into the different parts of the body.
Each long bone is a hollow shell like the frame of a
bicycle. This makes it strong and yet light. Its hollow
inside is filled with a soft fat called marrow.
The ends of long bones are like a fine honeycomb
covered with a hard shell of firm bone. This makes them
light and yet able to resist the pressure of the body above.
306. Strength of bone. — Each bone is very hard, and
*55
i56
APPLIED PHYSIOLOGY
yet it can be bent somewhat without breaking. It is
twice as strong as an oak stick of the same size.
307. Structure of bone. — A bone is made of living cells
fed by the blood. From the cells there go out fine strings
of connective tissue. Lime is mixed among the strings
like starch anions^ the fibers of a linen collar. This makes
a bone cells.
Thin slice of bone ( x 200) .
b Haversian canal, containing blood vessels and nerves.
the bones hard. About one third of a bone is made of the
living cells and two thirds is lime. Under a microscope
we can see that the cells form circles around small blood
tubes.
A bone is covered with a tough membrane called the
periosteum. The periosteum forms new cells and makes
the bone grow. If the bone is removed and its periosteum
left, this will form a new bone in a few weeks. Bone
grows and wastes away, but it changes much slower than
any other part of the body.
The place where bones join together is a joint. Some
joints can bend and others cannot.
BONES 157
308. The skull. — The frame of the head is called the
skull. It is made of twenty-two flat plates of bone. Those
that cover the brain and the other parts of the head are
thick and strong, for they are likely to be hurt by blows.
The bones which make the nose and the inside of the
skull are thin, for they have little work to do, and blows
cannot reach them.
The bones of the skull are joined together by rough
edges, which fit exactly into each other. In a man some
of these bones grow together into a single bone. These
joints can move only enough to prevent a little of the
jarring when we jump or strike the head against something
hard, but in a young baby the bones can be moved and
the head can be pressed into any shape.
309. The spine. — The skull is balanced upon a stiff
string of bones called the spine or backbone. The spine
runs the whole length of the back, and is made up of
thirty-three rings of bone; but in a man the lower ones
grow together so that there are only twenty-six separate
rings. The spinal cord is hung in the middle of these
rings. Between the rings are thick, strong pads of tough
flesh or gristle which make strong, close joints, and also
act as springs to keep the body from being jarred when
we run or jump. By means of these joints the backbone
can be bent and twisted, but the motion is small. In the
circus are men whose backbones are so loose jointed that
they can twist themselves into a knot.
310. Ribs. — From the sides of the backbone slender
bones, called ribs, extend around the sides of the body,
and are joined in front to the sides of a flat bone called
the breast bone. There are twelve ribs on each side.
They have a little motion up and down, and out and in,
as in breathing. They form a box called the chest.
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APPLIED PHYSIOLOGY
311. The pelvis. — The backbone rests upon a large
and strong ring of bone formed by the hip bones. The
hip bones form a round bottomless basin called the pelvis,
There are three bones in the pelvis, and the joints between
them are close fitting and strong. We sit upon the bot-
toms of the two hip bones.
312. The legs. — From each side of the pelvis a long
bone reaches downward to form the framework of the leg
above the knee. This bone is called the femur, and is
the largest, longest, and strongest bone in the body.
Reaching from the knee to the ankle is a long and
strong bone called the shin bone or tibia. Upon its out-
side is a long slender bone called the fibula. The lower
end of the fibula forms the lump of bone which is called
the outer ankle bone. The inner ankle bone is formed by
a small tongue of bone from the tibia.
313. The instep. — Below the shin bone are seven small
rounded bones which are very tightly bound together by
strong bands of connective tissue. They form the instep,
or arch of the foot. This arch supports the weight of the
body while we stand. So it is made very strong. A single
bone would not spring, but the whole body would be jarred
at every step. The arch is made of several bones each of
which will spring a little. So when we jump or run, our
bodies are but little jarred. The pads between the rings
of the spine also keep the body from being jarred.
At the end of the instep are nineteen slender bones
joined end to end in five strings. The first bone of each
string is buried in the flesh, and together they form the
sole of the foot. They are called tarsal bones. The re-
maining bones of each string form the toes.
314. The shoulder. — Two bones at the lower part of the
neck upon each side form a frame upon which the arm is
BONES 159
hung. The bone in front is slender and long and is called
the collar bone, or clavicle. Its inner end rests against the
breast bone. The bone behind is flat and forms the shoul-
der blade, or scapula. It is not joined to any bone, but
is hung only by muscles. These two bones form the
shoulder.
315. The arm. — From the side of the shoulder a long,
strong bone hangs down to form the frame of the arm
above the elbow. It is called the humerus. At the elbow
it joins two other bones which form the frame of the arm
below the elbow. The bone upon the thumb side of the
arm is called the radius, and upon the little finger side,
the ulna.
316. The wrist and hand. — At the ends of the radius
and ulna are eight small, rounded bones which form the
wrist. These bones are firmly joined together by con-
nective tissue like the tarsal bones of the foot. They
make the wrist more springy than it would be if it were
a single bone.
At the lower end of the wrist are nineteen slender bones,
joined end to end so as to form five strings of bone as in
the foot. The first bones of each string are buried in the
flesh and make the frame work of the palm of the hand.
The outer bones of each string form the fingers.
-3L/317. Hand and foot compared. — The hand and foot are
ekch made of the same number of bones and upon the
same plan. The instep is much larger and stronger than
the wrist, for it must bear great weights. The toes are
much shorter than the fingers, but they have the same
muscles and can be moved in the same ways. The great
toe cannot be turned in so as to be brought against the
other toes as the thumb can against the fingers. The
foot would be a very clumsy hand, yet some persons who
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APPLIED PHYSIOLOGY
have been born without hands have learned to use their
feet instead.
318. Joints. — The bones of the skull and pelvis can be
moved but little. Their joints permit these bones to grow
and also make them slightly springy.
The bones of the spine, instep, ribs, and wrist can move
a little. Each bone moves scarcely enough to be notice-
able, but altogether they have a considerable range of
motion.
The bones of the arms, fingers, legs, and toes and the
lower jaw can be moved freely. In them the end of one
bone is rounded and fits snugly into a hollow in the other
bone. The two bones are bound together by tough bands
called ligaments, which encircle the joint like a loose col-
lar. Thus the bones are free to move like a door upon
its hinges.
-The ends of bones in the joints are
covered with a thin layer of a very
tough and firm substance called carti-
lage. Cartilage is like bone without
lime. The bone of young animals is
cartilage at first, but as it grows it
takes up lime, except at the ends, which
remain cartilage.
320. Synovial membrane. — The in-
side of a movable joint is lined with a
bag called the synovial membrane.
The synovial membrane is very smooth
and is filled with a liquid like the white
of an egg. This oils the joint and
makes it work smoothly. Sometimes
in old people the synovial fluid dries up. Then the joint
is stiff and creaks when it is bent.
319. Cartilage.
Hinge joint of the elbow,
i humerus 2 ulna
BONES l6l
321. Hinge joints. — In the fingers, toes, wrists, ankles,
elbows, and knees the surfaces of the joints are long and
round like a hinge. So they can open and shut in one
direction only like a penknife. In the other direction they
can only straighten the limb. If you bend the limb in the
wrong direction, you will break the bones or else put them
out of joint,.
322. Ball and socket joints. — The shoulders and hip
joints can be moved in any direction. In each the upper
end of the bone of the limb is round like half of a ball.
This fits into a cup in the other bone. Thus the limb can
be turned in any direction. In fourfooted animals the
fore and hind legs cannot be moved nearly so freely as a
man's arms and legs. So these animals could not do a
man's work even if they had hands.
323. Broken bones. — The bones of children are more
springy and are softer than those of old people. A child
may fall very hard without danger, while an old person's
bones will break from a slight fall. But a grown person
weighs many times as much as a child, and so, when he
falls, there is more strain on the bones.
When a bone is broken, its ends must be put in place,
or "set," and kept there by splints and bandages. Then
new cells grow in place of the injured ones. Lime is
mixed with the new cells, and the bone repairs itself in
about a month. It will then be as strong as it was before
it was broken, or even stronger. If the ends of the bones
are not put in their proper place and kept there until heal-
ing begins, the bone will grow crooked.
324. Sprains. — When a joint is bent too far, or in the
wrong direction, its ligaments are stretched and partly
torn. This makes a sprain. A sprained joint is very
tender and painful, and gets well slowly.
OV. PHYSIOL. (INTER.) — I I
1 62 APPLIED PHYSIOLOGY
When you sprain a joint, you should put it at once in
hot water for an hour or two. This will relieve the pain
and swelling. Then you should keep the joint at rest for
a few days.
325. Bones out of joint. — When the end of a bone is
out of its socket, the bone is out of joint. Then move-
ments of the limb will be painful or impossible. If a bone
gets out of joint, the ligaments become badly torn and
will heal slowly. A bone out of joint is as bad an injury
as a broken bone. It will be necessary to put the bone in
place and keep it there by splints and bandages. It is
treated like a broken bone.
326. Effects of improper positions. — When a bone or
joint is bent, it will return to its former shape. If it is
kept bent in one direction a large part of the time, it
slowly grows into that shape. If you always lean to one
side while sitting at the desk, the backbone will finally
become curved in that direction. If you sit round-shoul-
dered, after a while your bones and joints will make you
keep that shape. A round-shouldered person has small
lungs. He is apt to be short-winded.
327. Tight shoes. — If your shoes are tight, they will
cramp your toes and make them grow out of shape. The
big toe of a baby points forward in a line with the inside
of the foot. It points forward in very few men or women,
for their tight shoes force it inward until it stays in that
position. The ends of the toes should be square with the
sides of the feet. Tight shoes cramp the toes and make
them pointed. When the tight shoe rubs the skin, it causes
the epithelium to thicken and form a corn. If it forces the
big toe inward, it harms its joint, making it swell and be-
come painful. This forms a bunion. The cure for corns
and bunions is to wear loose shoes of the shape of the foot.
BONES 163
By sitting, standing, and walking erect, we can make
our backbones straight and our chests full. A soldier is
straight because he has had to keep his back straight until
it grew so..
SUMMARY
1. Two hundred bones form a strong frame for the body.
Some are long and some are flat.
2. Bones are made of living cells, in which lime is mixed
to give them stiffness.
3. The union of two bones is a joint. Some, as those of
the head, cannot be moved. They allow the bones
to spring a little instead of breaking, when they are
hit or pressed.
4. The bones of the spine can move a little, for they are
joined together by pads like rubber cushions.
5. In the arms and legs the bones fit together by means
of rounded surfaces. They are covered with car-
tilage and are held in place by loose ligaments.
6. Joints are oiled by a fluid like the white of an tggf
called the synovial fluid.
7. Most joints move back and forth like a hinge. The
shoulder and hip can be moved in any direction.
8. The cells of a broken bone soon fill in the gap with
the new cells, and then deposit lime in the new
part. This heals the bone.
9. In sprains, and when bones are out of joint, the liga-
ments are torn and require a long time to heal.
10. When the body keeps an improper position for days
at a time, it will grow into that position.
The muscular system.
164
CHAPTER XVII
MUSCLES
328. Use of muscles. — The bony framework of the body
is covered and rounded out by muscles. Muscles form
one half of our weight. They are the servants of the
mind, and do its physical work, while the brain does its
mental work. If the brain and
- — a muscles did not wear out, there
V;. A would be no need of a stomach.
- As it is, the stomach, heart,
< . lungs, and other parts are needed
_& to feed and to keep the muscles
and brain alive and well.
Muscle ceils, cut across 329. Structure of muscles. —
(x 200). Lean meat is mostly muscle. A
a muscle ceil. muscle is large at one end or in
b connective tissue binding the °
cells together. the middle, and is fast to a bone.
Its other end generally grows
smaller and is prolonged in a strong cord called a tendon.
The tendon crosses a joint and is fast to another bone.
Each muscular bundle is made of cells like strings.
These are the largest cells in the body, but they cannot
be seen without a microscope. They are bound in small
bundles by delicate strings of connective tissue. These
bundles are bound into a large bundle which we call a
muscle. Each large bundle of muscle is covered with a
thick woven skin of connective tissue. Finally, all the
165
l66 APPLIED PHYSIOLOGY
bundles of a limb are bound together by a very thick sheet
of the same tissue. You can see these bundles and their
tough coverings in any meat.
330. Action of muscles. — A nerve thread touches every
muscle cell. When it brings an order to act, each muscle
■ gu n cell makes itself thicker and
Bti shorter. Thus the whole muscle
becomes shorter and pulls upon
whatever is fast to its ends.
The usual action of a muscle
is to bend a joint.
The messages sent to the mus-
cles come from the cells of the
A thin slice of a voluntary mus- spinal cord. They send mes-
cle, cut lengthwise (x 100). gages tQ the musdes either in
a muscle cell. n . t ,, , ,
b capillaries surrounding the cells, a reflex way or when told to do
c connective tissue binding the so ^v the cells of the brain.
cells together.
Muscle and brain cells are the
only cells of the body which can be made to act when-
ever we wish them to.
331. Involuntary muscles. — There is a kind of muscle
which we cannot make act by an effort of the will, but
which the spinal cord keeps in action in a reflex way
without our knowledge. Such muscles are found in the
stomach, intestine, arteries, and skin. They are the
muscles which aid the digestion of food and the flow of
blood. The spinal cord and sympathetic system send them
orders without our knowledge. It is well that nature has
put these muscles beyond our control, for we might
forget to attend to them. They are called involuntary
muscles, because we cannot make them act. These mus-
cles are made of cells with long pointed ends. Instead of
being solid masses, they form thin leaves around tubes.
MUSCLES 167
332. How to see muscles. — Shut the hand tightly, and
notice that the arm just below the elbow becomes harder
and larger. This is because the muscles which shut the
hand are situated upon the arm. You can feel and see
the ridges formed by each bundle of muscle while it is
acting. You can feel their tendons as they cross the wrist.
Some end in the palm of the hand, and some go on to the
fingers. There are a few small muscles in the palm of
the hand, but most of the finger muscles are in the arm.
There are no muscles at all in the fingers.
The muscles of the foot are upon the leg below the
knee. They end in tendons which go to the toes like the
tendons to the fingers. The tendon above the heel sup-
ports the weight of the body when we stand on tiptoe. It is
the largest in the body, and is called the tendon of Achilles.
Muscles which bend a joint are usually much stronger
than those which straighten it, for most of our work is
done by bending the joints. . .
333. Strength of muscle. — Lean meat seems soft and
almost like jelly, yet it can contract with great force. The
muscle upon the front of a man's arm can put forth a force
of nearly a thousand pounds, but its tendon is attached so
near the elbow that we can really lift about a hundred
pounds with the hand. Most muscles have to put forth a
strength more than equal to the weight which they move.
A grasshopper seems to be very strong, for it can jump
a hundred times its own length. But a grasshopper is
very light, and has but little weight to carry. A piece of
man's muscle of the size of a grasshopper's is really far
the stronger.
334. How to increase the strength. — By use, a muscle
becomes larger and stronger. When a boy wishes to go
into a race, he uses the muscles of his legs every day until
1 68 APPLIED PHYSIOLOGY
they are large and hard, and he can run very fast and
long without getting tired. But using the muscles of the
leg does not make the arm stronger. We must use every
muscle if we would get strong all over.
If we stop using our muscles, they soon become weak
again. If you break your leg and have to keep it still, it
will soon become small and weak. Then the other one will
grow larger, for it has to work harder to carry you around.
If you use your muscles until you strain them, they will
grow weaker instead of stronger, for you will wear them
out faster than the blood can feed them. You ought not
to strain yourself trying to lift as much as a grown man
lifts, or to run as far as a large boy runs.
335. Round shoulders. — The muscles of our backs hold
us erect and keep our shoulders thrown back. A lazy boy
lets his shoulders fall, and supports himself by leaning
against the wall. Sometimes braces are used to keep the
shoulders back. This rests the muscles, and lets them
grow still weaker. The best way to make the body
straight is to make the muscles hold the shoulders back.
This is what soldiers do. Military drill tends to make
boys straight. Working women of Europe often carry
heavy burdens upon their heads. In order to do this, they
must walk erect and steady. These women are noted for
their straight backs and graceful walk. A drill in carrying
loads upon the head would be of great value in making
young girls walk gracefully.
336. How exercise makes the body healthy. — The mus-
cles are the engine of the body. The food is the fuel.
Oxygen burns the food and makes heat, which the muscles
turn to power. When a muscle acts, it needs a great deal
of heat. So it must have more food and air, which is
brought by the blood. In order to support it, the heart
MUSCLES 169
beats faster and stronger and the stomach acts better.
The whole body does better work so as to supply the
muscles with power. The brain also feels the effects of
the increased action of the body. Use of the muscles
makes us feel better in every way. When we have studied
or written all day, we have taken only a few deep breaths.
Our fires burn low and become clogged with waste matter.
If we now exercise for a few minutes, we shall start up all
the actions of the body and shall feel fresh again.
Some men work hard and are healthy until they get
rich. Then they stop work at once and try to enjoy their
rest. But they find that their food does not digest, and
that they cannot breathe well. Their brains are clouded
and their heads ache. The trouble is that their muscles
do not need food, and so the body does not prepare it for
them. If they should do light work, they would feel all
right.
We can use our muscles in order to grow strong. This
alone will not do us much good, for men can use machines
to do far more hard work than a large number of men can
do. We also use our muscles so as to grow healthy. This
should be the object of exercise. Every one should do
some work with his muscles every day. Girls and women
need exercise as well as boys and men.
337. How to exercise. — The best exercise is that in
which some useful work is done. A farmer's boy grows
strong and does not think of his exercise. Work about
the house or barn is the best kind of exercise. Every
child should have some regular work to do night and
morning. It will make him stronger and will also teach
him how to work.
It is well to teach boys and girls some trade. Carpen-
tering is exercise, and also gives them useful knowledge.
170 APPLIED PHYSIOLOGY
Gardening and housework are also exercise, and should be
taught to every child.
A bicycle affords good exercise. If a person does not
race or go on long rides, it will do him no harm. Even
old men and very small children can ride it safely.
Gymnasiums are of great value in taking exercise. By
the use of dumb-bells and Indian clubs, and by lifting
light chest weights, any weak part of the body can be
made strong. The only trouble in the use of these is that
we soon get tired of one thing. In classes and under a
teacher they afford interesting and profitable exercise.
338. The face muscles. — The muscles of the face are
flat and fastened to the skin. When they act, they draw
Illustration of the change of expression produced by the muscles
of the mouth.
and pucker the skin in different directions. Each kind of
feeling in the mind causes the muscles to act in a certain
way. If we feel happy, the muscles draw the ends of the
mouth upward and backward. This makes a smile. If
we feel sad, the muscles draw the ends of the mouth
down. By looking at a person's face we can often tell
how he is feeling.
339. Effects of alcohol and tobacco. — Alcohol appro-
priates oxygen belonging to the muscle cells and prevents
the stomach and liver from preparing food for their use.
MUSCLES i;i
Consequently, it weakens the muscles. It may seem to
make a person stronger, for it deadens his tired feelings.
But in reality he has less strength than if he had let drink
alone. A single drink begins to weaken him. Alcohol
cannot take the place of food, for food is the only thing
to give strength to the body. Drugs may deaden tired
feelings, but they cannot add to one's strength.
Alcohol sometimes causes little drops of the muscle
cells to change to fat. This greatly weakens the cells.
Beer often does this. A man may seem to be very fat
and strong from its use, but fat does not give strength.
Tobacco is a poison to all the cells of the body, and it
never becomes anything else. No man who is training
for a race dares to use tobacco.
340. Alcohol and endurance. — Men sometimes have to
make long journeys across hot deserts or in cold Arctic
regions, or have to endure great fatigue and suffering in
war. It used to be thought that strong drink gave men
greater power for undergoing these heavy labors, and so
men in armies and exploring expeditions always carried
regular supplies of rum, which was doubled just before a
battle or an extra strain. Men who refused to drink were
laughed at ; but it was noticed that they did more work
and enjoyed better health than the drinkers. Then care-
ful experiments were made to determine whether men
could do without liquor. In every case men in hot cli-
mates felt better, while those in polar regions endured the
cold better than those who used it. The government
of the United States long since stopped giving liquor to
the soldiers and sailors. Arctic explorers do not carry it
except for scientific purposes. Even hard drinkers care-
fully avoid liquor while they are training.
A few years ago a man would have been called foolish
172 APPLIED PHYSIOLOGY
if he did not drink while doing hard work. Mowers each
took a drink from a common jug at each round of the field.
One man remarked, " I could mow without rum as well as
any one if it were not for the looks of the thing." Rum
was used freely at every church raising. Now all this has
changed. Fashion no longer requires men to drink. On
the other hand there is a growing knowledge of its harm,
and an increasing custom of letting drink alone.
341. Tobacco and strength. — Formerly men thought
that tobacco helped men to work hard and to endure fa-
tigue. Now men know better, but because its effects are
not so great as those of alcohol, men are slower in giving
up its use. Still its effects are so great that men who
train for races will not use it any more than they would
strong drink.
It is everywhere admitted that the use of tobacco by the
young hinders the growth of the body. Careful measure-
ments of young men in schools and colleges show that
smokers do not grow so fast nor so large as those who
do not smoke. Cigarettes are especially harmful to the
young, and yet boys and young men are almost the only
persons who buy them.
342. Life insurance and drinking. — The most convinc-
ing proof of the evil effects of strong drink is the records
of life insurance companies. When a person asks to be
insured the company makes a careful inquiry and an ex-
amination to find out the state of the candidate's health and
his habits in regard to drinking. If he is accepted he pays
a certain sum each year. Then, after a certain number of
years, or at his death, a sum of money is paid to him or to
his family. A person at any given age may be expected
to live and to pay premiums for a certain number of years.
Some die sooner and some live longer; but the amount
MUSCLES 1 73
which they all pay nearly equals the amount which the
company had calculated they would have paid if all had
lived a given number of years. According to life insur-
ance tables a healthy man, at 20 years of age may expect
to live 44 years more ; at 30 years of age, 36 years more ;
and at 40 years of age, 28 years more. If a man is a mod-
erate drinker, at 20 years of age, he may expect to live 15
years more ; at 30 years of age, 14 years more ; and at 40
years of age, 1 1 years more. As a mere matter of busi-
ness a company will not insure a drinker, for they cannot
afford to pay a large sum of money if the person is not
likely to live long to make them yearly payments. Thus,
a healthy man insured at 20 years of age, will make yearly
payments for 20 years longer than a drinker.
343. Why strong drink shortens life. — Strong drink is
a poison which is strong enough to produce death in itself.
A great many drinkers die from the effects of strong drink
alone.
Strong drink also weakens the body so that it cannot
resist diseases which it otherwise could endure. In epi-
demics of small pox, cholera, yellow fever, and such deadly
diseases, drinkers are more apt to take the disease than
those who do not. Of the sick, drinkers are the first and
often the only ones to die. Surgeons hesitate to oper-
ate upon drinkers, for their wounds heal slowly, and they
take chloroform poorly. It is true that some drinkers
escape the greater dangers of alcohol, but the risk that a
drinker runs of being seriously harmed or killed, is far
greater than the risk that a soldier runs of being hurt in
a battle.
344. A long life. — A healthy body is the noblest work of
nature. Such signs as hunger and taste lead man to nourish
his body, and pain and fatigue warn him to avoid dangers.
174 APPLIED PHYSIOLOGY
If he heeds these signs his mind and body will work
together as one for seventy years and more. He will be
able to resist germs of disease, while no cause of sickness
will arise within the body itself. He will go through life
with a buoyant sense of strength, eager to do the work
which his thoughts are ever planning.
SUMMARY
i. Muscles cover the bones and move the joints.
2. A muscle is a bundle of stringlike cells. When nerves
bring it orders to act, it makes itself shorter and
pulls its ends together.
3. A muscle usually ends in a long tendon which crosses
a joint and is fastened to another bone.
4. Muscles are lean meat. They can be felt in the arms
and legs.
5. By use, a muscle grows larger and stronger.
6. By too great use, a muscle is used up faster than the
blood builds it again.
7. The power of a muscle comes from the heat of oxi-
dized food.
8. In exercise a muscle needs more food and air, which
the stomach, heart, and lungs supply by working
harder.
9. Useful and interesting work is the best exercise.
10. Alcohol keeps the stomach from preparing food for
the muscles, and takes away their oxygen. Thus it
diminishes their strength.
11. Tobacco poisons the muscles.
12. By living as well as we know how, we shall keep the
body strong and healthy until old age.
GLOSSARY.
Ab-do'men, the inside of the lower part of the body.
Abscess (ab'sess), a collection of creamy matter in the flesh, as a boil.
A-chil'les, an old Greek warrior who could not be harmed excepting in
the heel, where he finally received his death wound. Hence the
tendon at the heel is named after him.
A-dul'ter-ate, to mix a poor substance with a better one so as to
sell the whole for the price of a good article.
Al-bu'min, a substance in the body like the white of an egg. It is
found in all living cells and must be supplied with the food.
Al'co-hol, a clear liquid of a burning taste and smell. It is found in
all strong drinks and gives them their poisonous qualities.
A-me'ba, a low form of animal consisting of a single microscopic lump
of albuminous jelly.
Ap'pe-tite, the desire for food or drink ; the desire to satisfy a taste.
Ar'ter-y, a tube which carries blood away from the heart and toward
the cells of the body.
Ar-ti-fi'cial res-pir-a'tion, causing air to pass in and out of the lungs
of an insensible person.
Au'ri-cle, one of the two thin upper pockets of the heart.
B.
Bac-te'ri-a, the simplest form of living beings. They are plants like
tiny balls or rods. They produce decay, and some produce disease
in the human body. They are also called microbes and germs.
Bile, a bitter yellow fluid formed by the liver and poured into the
intestine. It is a waste product, but on its way out of the body it
assists digestion.
Brain (brane), the nervous matter in the skull. By means of it we
think, feel, and move.
Bron'chus, one of the wind tubes of the lung.
175
1 76 GLOSSARY
C.
Callus, a hard and thick spot of epithelium upon the skin. It comes
as a result of work, to protect the skin from injury.
Cap'il-la'ry, one of the fine tubes into which arteries pour the blood.
They surround each cell and give out blood and air to it.
Car-bon'ic a'cid, a gas formed by burning and by oxidation in the
body. It is given off in the breath.
Car'ti-lage, a substance which covers the ends of bones within joints.
It is often called gristle. It is like bone without lime.
Cell, the smallest part of the body which can live when separated from
the rest. The smallest unit of the body. A cell, when cut, dies.
Cer-e-bel'lum, the rounded part of the brain projecting backward from
its under side. It assists in performing movements of balancing.
Cer'e-brum, the large upper part of the brain. It feels, thinks, and
produces motion in the rest of the body.
Chloral (k/o'raf), a peppery-tasting, poisonous solid which produces
sleep.
Cilia (sil'i-a), tiny waving hairs upon the surface of cells. They are
found in the epithelial cells lining the air tubes.
Cir-cu-la'tion, the flow of blood through the body.
Clav'i-cle, the collar bone. It extends from the middle of the front of
the body to the shoulder.
Co'ca-ine, a substance which benumbs feeling when applied to nerves.
Cold, a sickness caused by exposure to cold and dampness. This
injures the cells and permits bacteria of disease to grow upon them
and produce disease.
Con-nect'ive tis'sue, the fine fibers which bind the cells of the body in
place. #
Cook'ing, the preparation of food for eating by the use of heat.
Cor'ne-a, the round, clear window in the front of the eye, which admits
light to the inside.
Cor'pus-cle, a cell found in the blood.
D.
De-lir'i-um tre'mens, a mental trouble in which the mind seems to
see foul animals and reptiles. It is caused by strong drink.
Der'ma, the true skin. It forms almost the entire thickness of the
skin, and contains its nerves and blood tubes.
GLOSSARY
177
Di-ges'tion, the process of changing food to a liquid which will pass
through the sides of a capillary and into the blood.
Dis-til-la'tion, changing a liquid to steam, and then collecting and
cooling the steam until it forms a liquid again. It is used in makino-
alcohol and in obtaining pure water.
Drug, a substance which can affect the body when taken in a small
quantity. A medicine.
E.
En-am'el, the hard outer shell of a tooth.
Energy (en'er-jy), force which can be used to make a machine work.
The energy of the body comes from burning or oxidizing the food.
Ep-i-der'mis, the thin outside part of the skin, which has no feeling.
It is composed of cells of epithelium.
Ep-i-the'li-um, the cells which cover the surface of the skin and of
mucous membranes, and which line the tubes of all glands.
E-soph'a-gus, the tube down which food is swallowed.
Eustachian (Yu-sta' ki-an) tube, the tube leading from the middle ear
to the throat. It is named after an Italian physician who died
in 1574.
Ex-pi-ra'tion, driving air from the lungs.
F.
Faint'ing, losing the senses, with great paleness. It is caused by a
sudden weakness of the heart, often due to fright.
Fe'mur, the thigh bone, reaching from the hip to the knee.
Fe'ver, a sickness in which the heat of the body is increased.
Fib'u-la, the bone extending from the knee to the ankle upon the out-
side of the leg.
Fil'ter, a box filled with sand, charcoal, or other porous substance.
It takes impurities out of water which is run through it.
Food, anything which, when taken into the body, can add to its weight,
or become oxidized and produce heat and energy.
Gan'gli-on, a collection of nerve cells, especially those in the sympa-
thetic system.
Gas'tric juice, the fluid which the stomach forms to digest food.
OV. PHYSIOL. (INTER.) — 12
1 78 GLOSSARY
Germs, tiny living plants which cause catching diseases. They are
also called bacteria and microbes.
Gland, a collection of tubes made of epithelial cells which produce
a substance out of the blood.
H.
Heart, the muscular pump which forces blood through the body.
He-red'i-ty, the influence which is transmitted at birth from parents to
children.
Hu'mer-us, the bone of the upper arm, extending from the shoulder to
the elbow.
I.
In-flam-ma'tion, heat, swelling, redness, and pain in a part. It is the
result of an injury and generally is associated with the growth of
disease germs.
The heat, swelling, and redness are due to an increased flow of blood
to repair the injury. The pain is due to pressure upon the nerves
owing to the increased flow of blood.
In-spi-ra'tion, taking air into the lungs.
In'step, the arch of the foot.
In-tem'per-ance, eating or drinking for mere pleasure, or when the
body does not require nourishment.
In-tes'tine, the tube in the lower part of the body, into which food
passes from the stomach, and in which it is mainly digested.
In-vol'un-ta-ry mus'cle, a muscle which acts without regard to our
knowledge or effort, as the muscle of the heart or stomach.
J-
Joint, the union of two bones, whether flexible or not.
K.
Kid'ney, a red gland which separates urea and other waste matters
from the blood.
L.
Lac'te-al, one of the lymphatic tubes which begin in a villus and earry
away digested fat.
Larynx (iar'inks), the box made of cartilage situated at the beginning
of the windpipe. In it the voice is produced.
GLOSSARY 179
Lens, a part of the eye, shaped like a small burning glass. It brings
light to a point and forms an image of an object upon the back of
the eyeball.
Lig'a-ment, the tough bands which bind bones together at joints.
Liv'er, the gland above the stomach which forms the bile and changes
digested food to blood.
Lung, a spongy bag from which the red blood cells get air to carry to
the cells of the body.
Lymph, the part of the blood which leaves the capillaries to feed the
cells.
Lym-phat'ics, the fine tubes which carry lymph back to the blood.
Lymph nodes, small bodies through which lymph flows as through a
sponge. These can be felt in the groin and neck. They strain
poisons from the lymph.
M.
Malt, barley sprouted and grown until the new shoots are about half an
inch in length, and then dried. It is used in making beer.
Mar'row, the fat from the inside of hollow bones.
Me-duTla. the part of the brain just above the spinal cord. It sends
orders for the movements of respiration.
Mem'o-ry, an action of the brain which can be recalled.
Mi'crobes, disease germs. The same as bacteria and germs.
Mi'cro-scope, an arrangement of glasses which make small things seem
large to the sight.
Mo'tor nerves, nerves which carry impressions away from the brain,
and toward the cells of the body. These impressions cause the
cells either to grow, or to move.
Mu'cous mem'brane, the skinlike lining of the inside parts of the
body which connect with the air. It lines the passages by which
food and air are taken in.
Mu'cus, the thin slimy fluid which mucous membranes produce. It is
to the mucous membranes as the sweat is to the true skin.
Mus'cle, a collection of cells whose duty is to produce motion.
N.
Nar-cot'ic, any drug which will benumb pain and produce sleep, as
opium.
Nerve, a collection of threads which carry messages between the cells
of the spinal cord or brain and the cells of- the body.
l80 GLOSSARY
Ner'vous-ness. a lack of control of the mind over the messages of the
nerves. When slight impressions of the nerves cause discomfort, a
person is nervous.
Nic'o-tine, a very poisonous liquid found in tobacco. It gives tobacco
its taste and smell, and produces its poisonous effects.
Ni'tro-gen, a gas which forms | of the air. It has no effect on the
body, but its only use is to dilute the oxygen.
O.
O-le-o-mar'ga-rine, an imitation of butter, made of beef fat.
O'pi-um, the juice of the poppy plant. It benumbs pain and produces
sleep, and is thus a narcotic. Some men learn to use it as others do
tobacco. It is a poison.
Ox-i-da'tion, the union of oxygen with a substance ; burning. In
breathing, oxygen from the air unites with the cells of the body,
slowly burning them, and producing heat.
Ox'y-gen, a gas which forms one fifth of the air. Its uniting with other
substances is burning.
Pan'cre-as, the gland which forms the pancreatic juice ; the sweet-bread.
Pan-cre-at'ic juice, the fluid which the pancreas pours into the intestine.
It does most of the work of digestion.
Pa-ral'y-sis, a state of the body in which it is impossible to move or to
use some of its parts.
Pel'vis, the heavy ring of bone formed mainly by the hip bones. Its
inside contains a part of the intestine.
Per-i-os'te-um, the tough, skinlike membrane covering the bones, and
carrying their blood tubes. It produces new bone cells and so
causes a bone to grow.
Per-spi-ra'tion, the fluid produced by the skin ; the sweat.
Pharynx (far' inks'), the muscular bag back of the nose and mouth.
Through it both food and air pass.
Plas'ma, the liquid part of the blood.
Poi'son, a substance which can harm the body when taken in a small
quantity.
Pu'pil, the round opening in the iris or colored part of the eye. It
appears black.
Pus, the white, creamy matter in a boil or other abscess.
GLOSSARY i8l
Ra'di-us, the bone upon the thumb side of the arm, extending from the
elbow to the wrist.
Re'flex ac'tion, the act of the spinal cord in sending orders for action
in response to information from the cells. It provides for the wants
and for the protection of the cells.
Sa-li'va, the fluid always found in the mouth. It moistens the mouth,
softens food, and turns starch to sugar.
Scap'u-la, the flat bone behind the shoulder; the shoulder blade.
Sen'ses, the five means by which the mind gets knowledge of the world
outside of the body. They are seeing, hearing, feeling, smelling,
and tasting.
Sen'so-ry nerve, a nerve which carries impressions from the cells to
the spinal cord or to the brain.
Sew'er, an underground tunnel which carries away slops from houses.
Skel'e-ton, the bones of the body.
Skull, the bony structure of the head.
Spi'nal cord, the nervous cord inside the backbone. It gives off
nerves, sends reflex orders to the cells, and conducts impulses to
and from the brain.
Starch, a food substance found in nearly all kinds of vegetable food.
Corn starch and common laundry starch are two kinds.
Stim'u-lant, from a Latin word meaning a whip ; a substance which,
like a whip, compels the cells to act, but does not furnish them with
the power to act.
Stom'ach, the muscular bag into which food enters when it is swal-
lowed.
Su'gar, a sweet vegetable food substance. There are many different
forms, but during digestion all become changed to the kind of sugar
found in the grape.
Sweat, the fluid produced by the skin ; the perspiration.
Sym-pa-thet'ic sys'tem, the collection of nerve cells and nerves which
send orders to the muscles of the arteries, stomach, intestine, and
heart.
Syn'o'vi-a, a fluid like the white of an egg, which is found inside of
joints.
1 82 GLOSSARY
T.
Tar'sal bones, the short bones in the hinder half of the foot.
Tears, the saltish liquid which runs over the eyeball.
Ten'don, a strong cord connecting a muscle with a part to be moved.
Tho-rac'ic duct, a tube like a goose quill, which extends up the front
side of the backbone, and carries the lymph to the blood.
Tho'rax, the part of the inside of the body which is covered with ribs.
Tib'i-a, the shin bone, extending from the knee to the ankle.
To-bac'co, a narcotic plant used in smoking and chewing, and as snuff.
U.
Ul'na, the bone extending from the elbow to the wrist upon the little
finger side of the arm.
U're-a, the solid waste of the body. It is the ashes of albumin, and is
taken from the blood by the kidneys and skin.
V.
Vein (vane), a tube carrying blood away from the cells and back toward
tne heart.
Ven-ti-la'tion, replacing the impure air of a room with pure air.
Ven'tri-cle, one of the thick lower pockets of the heart.
Vil'lus, one of the tiny fingers which project into the intestine from its
mucous membrane.
Vo'cal cords, the bands in the larynx, which are set in motion by air
to form the voice.
Y.
Yeast, microscopic plants, each made of only a single cell. By their
growth they form alcohol and a gas. In making bread, the gas
bubbles through the dough and puffs up the loaf until it is light.
Yeast cakes are a kind of dried bread dough.
INDEX
Abdomen, 21.
Abscess, 75.
Achilles, tendon of, 167.
Adam's apple, 88.
Air, 11, 83, 92.
Albumin, 9, 22, 26, 61.
Alcohol, 50.
Alcohol and arteries, 69.
blood, 68.
candy, 140.
character, 134.
cooking, 139.
digestion, 52.
eyes, 147.
feeling, 133.
healing, 78.
heart, 70.
heat, 102.
heredity, 135.
kidneys, 112.
laws, 54.
life insurance, 172.
liver, 53.
lungs, 90.
medicine, 54, 140.
motion, 133.
mouth. 51.
muscles, 170.
nerves, 132.
Alcohol and nose, 151.
oxidation, 52, 89.
skin, 112.
spinal cord, 132.
stomach, 51.
taste, 152.
thought, 132.
treating, 141.
waste of body, 136.
Ameba, 7, 15, 66.
Aorta, 63.
Appetite, 36.
Arsenic, 42.
Arterial blood, 65, 83.
Artery, 61.
Artificial respiration, 87.
Ashes, 9, 11.
Auricle. 63.
Back bone, 157.
Bacteria, 73.
Baths, 109.
Beans, 29.
Bedrooms, 94.
Beer, 56.
Bile, 23.
Biliousness, 24.
Bitters, 137.
183
1 84
INDEX
Bleeding, 61, 72.
Blister, 105.
Blood, 15, 60, 65, 83.
Bone, 155, 161.
Bowels, 24.
Brain, 122.
Brandy, 57.
Bread, 29.
Breast bone, 157.
Breathing, 81.
Bright's disease, 109.
Bronchi, 80.
Bunion, 162.
Burns, 97.
Butter, 27.
Callus, 105.
Capillary, 62, 83.
Carbolic acid, 41.
Carbonic acid, 11, 83, 108.
Cartilage, 160.
Cells, 8, 66, 84, 117, 123.
Cereals, 29.
Cerebellum, 122.
Cerebrum, 122.
Cheeks, 17.
Cheese, 27,
Chest, 81, 157.
Chewing gum, 139.
Chloral, 47.
Chloroform, 141.
Chyme, 22.
Cider, 55.
Cigarettes, 46.
Cilia, 81.
Circulation, 64.
Clams, 28.
Clavicle, 159.
Clot, 61.
Clothing, 86, 99, in.
Coffee, 33, 138.
Cold blooded, 101.
Cold, taking, 75, 98.
Cold feelings, 95.
Connective tissue, 8, 66.
Cooking, 15.
Corn, 162.
Corpuscles, 60.
Cotton, 100.
Crabs, 28.
Cream, 27.
Cross-eyes, 145.
Cutis, 104.
Deafness, 149.
Delirium tremens, 135.
Derma, 104.
Diaphragm, 21, 81.
Digestion, 15.
Distillation, 56.
Dreams, 131.
Drowning, 88.
Drugs, 39> I37-
Drunkenness, 53, 133.
Ear, 147.
Eating, 36.
Eggs, 28.
Enamel, 17.
Epidermis, 105.
Epiglottis, 20.
Epithelium, 18, 105.
INDEX
I85
Esophagus, 20.
Ether, 141.
Eustachian tube, 149.
Exercise, 68, 167.
Eye, 144.
Fainting, 68.
Far sight, 147.
Fat, 10,23,24, 26, 171.
Fear, 130.
Femur, 158.
Fermentation, 49.
Fever, 96.
Fibula, 158.
Filter, 33.
Fire drill, 130.
Fish, 28.
Food, 11, 13, 26, 31, 41.
Foot, 159.
Frost bites, 98.
Fruit, 29.
Fur, 100.
Ganglion, 119.
Gastric juice, 21.
Gelatine, 9.
Glands, 18, 21. 108.
Goose flesh, 107.
Gray matter, 117, 123.
Gymnasium, 170.
Hand, 159.
Hangnail, 106.
Healing, 71, 75.
Hearing, 124, 148.
Heart, 63.
Heat, 95, 99, 144.
Heredity, 129.
Hip, 158.
History of strong drink, 57.
Humerus, 159.
Hydrochloric acid, 21.
Inflammation, 74.
Insect stings, 42.
Inspiration, 81.
Instep, 158.
Intemperance, 35.
Intestinal juice, 22.
Intestine, 22.
Iris, 144.
H
Habit, 128.
Hair, 106.
Jaws, 17.
Joint, 156, 160.
Kidney, 109.
Lacteal, 24.
Larynx, 88.
Laudanum, 41.
Lens, 145.
Ligaments, 160.
1 86
INDEX
Lime, II.
Liver, 23.
Lung, 80.
Lymph, 66.
Lymphatics, 67.
Lymph nodes, 67.
M
Malt, 56.
Marrow, 155.
Meat, 28.
Medulla, 122.
Memory, 124.
Milk, 27.
Mind, 8, 131.
Minerals, 11, 25.
Morphine, 41, 47.
Motion and brain, 124.
Mouth breathing, 85.
Mucous membrane, 18.
Mucus, 18.
Muscle, 28, 166.
N
Nail, 105.
Narcotics, 44.
Near sight, 147.
Nerves, 114, 166.
Nervousness, 129.
Nicotine, 44.
Night air, 94.
Nitrogen, 83-
Nose, 150.
Nuts, 30.
Oleomargarine, 31.
Opium, 41, 47.
Oxidation, 11, 84, 95,
168.
Oxygen, 11, 83, 92.
Oysters, 28.
Pain, 74, 116, 143.
Pancreas, 22.
Papilla, 104.
Paregoric, 41.
Pelvis, 158.
Pepsin, 21.
Peptone, 22, 24.
Periosteum, 156.
Perspiration, 96, 108.
Pharynx, 19.
Plasma, 61.
Poisons, 40.
Potash, 11.
Potatoes, 29.
Pulse, 66.
Pupil, 144.
Pus, 75.
Radius, 159.
Red blood cells, 60, 83.
Reflex acts, 118.
Respiration, 80.
Ribs, 157.
Root beer, 56.
108,
INDEX
I87
Saliva, 19.
Salt, 11, 30.
Scapula, 159.
Scar, 75.
Sensation, 116.
Senses, 124, 143.
Serum, 61.
6 ewer, 1 1 1 .
,Shinbone, 158.
Shortness of breath, 85.
Shoulder blade, 159.
Sickness, 39, 78, 94.
Sight, 124, 144.
Skin, 104.
Skull, 157.
Sleep, 127.
Slops, in.
Smelling, 124, 150.
Smoking, 46.
Snake bites, 42.
Snuff, 47.
Sound, 148.
Speech, 126.
Spices, 30.
Spinal cord, 117.
Spine, 157.
Sprain, 161.
Starch, 10, 19.
Stimulant, 34.
Stomach, 20.
Sugar, 9, 10, 19, 24, 26.
Sunstroke, 97.
Swallowing, 20.
Sweat, 108.
Sweetbread, 22.
Sympathetic system, 119.
Synovial membrane, 160.
Tarsal bones, 158.
Tartar, 17.
Taste, 124, 151.
Tea, 33, 138.
Tears, 146.
Teeth, 16.
Temperature sense, 144.
Tendon, 164.
Thinking, 125.
Thoracic duct, 67.
Thorax, 81.
Tibia, 158.
Tobacco, 39, 44, 91.
Tobacco and brain, 138.
digestion, 45.
drink, 138.
eyes, 147.
heart, 70.
lungs, 90.
mouth, 45.
muscles, 170.
smell, 151.
taste, 152.
teeth, 17.
Tongue, 17.
Touch, 124, 143.
U
Ulna, 159.
Urea, 108.
Vegetables, 29.
Vein, 63.
Venous blood, 65, 84.
188
INDEX
Ventilation, 93.
Ventricle, 63.
Villi, 23.
Vinegar, 49.
Vocal cords, 88.
Voice, 88.
W
Waste of body, 108.
Water, 9, 11, 25, 26, 32, 108.
Wells, 32, in.
Whisky, 57.
White blood cells, 60.
White matter, 117, 123.
Windpipe, 80.
Wine, 55.
Worry, 128.
Woolen, 100.
Yeast, 49.
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