IRLF

B M ID (a

ELEMENTS
PHVsfoLOGY

COLEMAN

UNIVERSITY OF CALIFORNIA

DEPARTMENT OF EDUCATION

GIFT OF THE PUBLISHER
No. Received / ) Of

C j~£0-

THE ELEMENTS OF PHYSIOLOGY

THE ELEMENTS OF

PHYSIOLOGY

FOR SCHOOLS

BY

WALTER MOORE COLEMAN, A.B.

FELLOW OF THE PHYSICAL SOCIETY OF LONDON; AUTHOR OF " SOCRATIC

LESSONS IN SCIENCE FOR TEACHERS," " CONTRACTILITY OF A

MUSCLE CELL," "ELEMENTARY PHYSICS," ETC.

WITH 248 ILLUSTRATIONS, INCLUDING COLORED
PLATES AND MANIKIN

gorfe
THE MACMILLAN COMPANY

LONDON : MACMILLAN & CO., LTD.
1904

All rights reserved

COLEMAN'S PHYSIOLOGICAL SERIES.

PHYSIOLOGY FOR BEGINNERS. For Intermediate
and Lower Grammar Grades. Illustrated with many
half-tone engravings and figures. 181 pages.

THE ELEMENTS OF PHYSIOLOGY. For an ex-
tended course in Graded Schools and Rural Schools,
and for a review course in High Schools, Academies,
and Normal Schools. With 248 illustrations, includ-
ing colored plates and manikin, xi -f 358 pages.

COPYRIGHT, 1903,
BY THE MACMILLAN COMPANY.

Set up, electrotyped, and published August, 1903. Reprinted
November, 1903; February, 1904; August, 1904.

Norwood Press

J, S. Gushing & Co. — Berwick & Smith Co.
Mass., U.S. A

TO THE TEACHER

THE human body is made of cells and its life consists
in the activities of the cells. Physiology is the study of
the cells and tissues in their related activities. Yet the
usual school physiology neglects the functions of the
cells and tissues and studies organs almost as isolated
things, rather than as component parts of the bodily
structure. The well organized science of physiology is
thus slighted and the result is an unnecessary waste of
time. The experience of the author with young students
has convinced him that elementary facts in the science are
not so difficult of comprehension when given in their real
relations as when given as isolated facts.

But due regard solely for logical order would require that
the pupil be inducted at once into the study of protoplasm
and cells, which are to him mysterious subjects. The
interest naturally excited by beginning a new study would
be killed before he reached things that he knows some-
thing about. The science of teaching requires that we
begin with things well known to the pupils and proceed
through the known to the unknown. Evidently no subject
is so well adapted for the starting point as the skin. The
surface of the body is familiar ; personal appearance is a
subject of interest to young people ; for these reasons the
skin is a suitable subject for introducing the stucty. Cell-
life being an unknown subject, it is treated at first in the
simplest and most elementary manner, but constant return
to it is made in the discussions of each organ and func-
tion. As the nerves are intimately related to every
organ, some authors attempt an exhaustive treatment of

VI TO THE TEACHER

the nervous system in the first chapters, but this method
has the insuperable objection of treating the most difficult
subject first. Recent authors have relegated the simple sub-
ject of the skeleton to the last as it is supposed to be the
least interesting and of least importance hygienically. In
this book it is introduced among the first chapters, because
a knowledge of the skeleton furnishes a scheme by refer-
ence to which all the organs of the body may be located as
studied, thus promoting a definite knowledge of anatomy,
without which foundation physiology cannot be learned.

The teacher will notice the incorporation of frequent
exercises, thought lessons, applications, and practical ques-
tions as a training for the reasoning faculty. These were
tested by a number of teachers with hundreds of pupils
before being set in type. Where they may seem ambig-
uous, it is usually because more definite statements would
be equivalent to giving the pupil the answers.

That the power of observation may be cultivated, fre-
quent observations of the pupil on his own body and on the
life of the community are called for, and after the more im-
portant figures and plates quizzes are inserted which can
be answered only by studying them.

It is said that there is no impression without expression,
and to supplement the work of the recitation in this
connection, numerous subjects for compositions and debates
are given. It is hoped that the teacher will not allow his
classes to lose the interest and enjoyment that the reading
of these essays, and debates at regular intervals, always
bring. It is suggested that " match reviews " (an adap-
tation of the old-style spelling match), " competitive drills,"
written exercises, and other forms of review be used.

It seems to the author that the time has come for a
more natural and logical, and therefore a more effective,
presentation of the subject of temperance than past methods
have furnished. In this book the purpose is to present the

TO THE TEACHER vti

blessings of natural incitants, and to show how, if these
incitants are taken advantage of by a healthful mode of
living, no craving for poisonous stimulants need ever arise.
In other words, the temperance teaching is positive rather
than negative ; it dwells upon happy things more than
upon the unhappy. As to amount and arrangement of
the space devoted to temperance, the book will be found
to comply fully with the laws of the different states on
this subject.

The present backward state of methods in teaching
physiology is probably to be attributed to the fact that the
text-books have been written by physicians, who, by reason
of the duties of their noble and arduous profession, have not
had time or opportunity to learn much about teaching. The
point of view of their profession may also explain why so
many physiologies are written from the standpoint of sick-
ness instead of from the optimistic standpoint of health
and strength.

Language and mathematics have been taught in the
schools for centuries ; the majority of the natural sciences
have not been taught for more than half a century, which
is all too short a time in which to learn to teach them
most effectively. The present book is an effort toward
raising physiology as a disciplinary study to the plane of
grammar and arithmetic, with the idea also that the reasoning
required in the many exercises will help to more thorough
understanding, and therefore better remembrance, of what is
learned. What should we think of an arithmetic or a gram-
mar in which every question was explained, every exercise
worked out, and consequently everything a matter of
memory and learning by rote ? Yet in exactly this way
have the school physiologies been written, and with such
books the teacher has had small chance to keep the pupils
from learning physiology by rote.

It has been the purpose to lead the pupil to approach

Viii TO THE TEACHER

every question in the scientific spirit. This means careful
observation, candor of mind, and patient suspension of
judgment until sufficient grounds for a conclusion are
forthcoming, and if they do not exist, then to leave the
question unsettled.

The recent addition of tropical islands to our territory
and the number of our citizens that go thither in military
and civil service, together with the semi-tropical climate of
our Gulf states, have led the author to deem care of the
health in warm climates a topic of sufficient importance to
require special references to it.

Those illustrations which are not original are taken
from the works of Huxley, Testut (Anatomie Humaine\
Kellogg, Thornton, Foster, Fabre, and Sappe"e. The author
has taken pleasure in designing the colored plates and
manikin, as so many schools lack facilities for instruction
and as dissections are seldom advisable. The handsome
execution of the numerous line engravings and colored
plates testifies to the liberality of the publishers and to their
purpose to' place this work in the schools in the form most
useful and instructive to the pupils.

Sincere thanks are returned to the following persons for
valuable aid in reading the proof : W. S. Carter, M.D.,
Franklin W. Barrows, M.D., Alfred Patton, M.D., J. W.
Thomason, M.D., J. Philip Gibbs, M.D., D. W. Lewis, A.M.,
H. C. Pritchett, A.M., Mrs. Rosa Buchanan, Miss L. W.
Elliott, Miss A. Lawrence, and Professor R. B. Halley.

CONTENTS

PART I

INTR OD UCTOKY KNO WLED GE
CHAPTER I

PAGE

THE SKIN i

CHAPTER II
CELLS AND TISSUES 25

CHAPTER III
THE SUPPORTING TISSUES -34

CHAPTER IV
THE MASTER TISSUES 44

CHAPTER V
SUBSTANCES FORMING THE BODY; OXIDATION. . . -51

PART II

HOW THE BODY IS MOVED

CHAPTER VI
THE SKELETON 56

CHAPTER VII
THE CIRCULATION 82

CONTENTS

CHAPTER VIII

PAGE

THE CIRCULATION — continued . 101

CHAPTER IX
THE MUSCLES 119

PART III

HOW THE BODY IS NOURISHED

CHAPTER X
THE RESPIRATION 147

CHAPTER XI
HYGIENE OF RESPIRATION 163

CHAPTER XII
FOOD 193

CHAPTER XIII
THE DIGESTION 204

CHAPTER XIV
HYGIENE OF DIGESTION 236

CHAPTER XV
STIMULANTS AND NARCOTICS . , . .

CONTENTS XI

PART IV

HOW THE BODY IS CONTROLLED
CHAPTER XVI

PAGE

THE NERVOUS SYSTEM 282

CHAPTER XVII
SOME SPECIAL REGULATIVE PROCESSES 320

CHAPTER XVIII
THE SPECIAL SENSES 334

APPENDIX
EMERGENCIES -355

ELEMENTS OF PHYSIOLOGY

PART I. INTRODUCTORY KNOWLEDGE
CHAPTER I

THE SKIN

1. The skin that covers our bodies is elastic and in this
respect is like India rubber. But if they are both exam-
ined under the microscope, a marked difference is found.
Rubber resembles oil and water in being alike in all its
parts, while the skin is composed of an immense number
of small objects fitting together. Hence it is said to
have a definite structure, while rubber has not. These
small objects are called cells and fibers: fibers are usually
thread-like, while cells are of various shapes. In another
chapter it will be learned that each cell has life and activity
of its own, and that the fibers are believed to be branches
from the cells. A number of cells or a number of fibers,
or both together, make what is called a tissue. The tissues
form organs. An organ is a part of the body that has
special work to perform and this work is called its function.
The skin is an organ and its chief function is to protect
the body. Name the organ of sight. What is the function
of the teeth ? A number of organs working together for a
similar end is called a system. Thus the organs which
prepare the food constitute the digestive system ; those
which circulate the fluids, the circulatory system.

2. The skin consists of two layers (Fig. i), the outer
layer, or epidermis, resting on the inner layer, the dermis,

B i

ELEMENTS OF PHYSIOLOGY

or cutis. The dermis is called also the true skin. The
epidermis is composed of a mass of cells held together
by a cement something like the white of an egg. Those
near the surface (Fig. 2) are hard and flattened;
those deeper down, near the dermis, are round and
soft. The lowest layers contain a pigment con-
sisting of minute grains of coloring matter. The

varying amount of this
pigment present causes

Epider- i '

mis or the difference in hue of
Cutide the blonde and brunette

Sweat
Glands

Dermis ^^^
or

races. Freckles are due
to an increase of pig-
ment in patches of
neighboring cells. Some
persons lack the pig-
ment entirely; their hair
and skin are white, the
eyes pink. They are
called albinos. Albinos
are found among vari-
ous species of animals.
Among the specimens
in the British Museum
there are albino (or pure
white) blackbirds, tur-
keys, etc.

3. The main part of the skin is the dermis, or cutis
(Fig. i); it is chiefly a network of fibers. This is the part
of the skin of animals that is tanned for leather. Did
you ever notice the fibrous appearance in the leather of a
shoe that has become much worn? Which side of leather
is smooth, the side covered by epidermis, or the other side ?
The human skin when tanned is said to make a leather

Nutrient A rtery
FIG. i. — Sectional View of the Skin, magnified.

Find: oil (sebaceous) gland, sweat gland, sweat duct,
hair bulb. Compare thickness of epidermis, dermis,
and subcutaneous tissue. (Thornton.)

THE SKIN

resembling the pigskin of which footballs are made. The
dermis is connected with the body beneath by a loose tissue
consisting of
fibers inter-
woven with cells
of fat (Fig. i).
This tissue, to-
gether with the
skin itself, partly
conceals the out-
lines of the
muscles be-
neath. Yet
artists study the
muscles care-
fully, as their
shape shows
faintly through
the skin and
gives a key to
the human
figure.

4. The outer
surface of the
dermis grows
into numerous
little projections
called papillae
(Figs, i and 2).
If its covering

FIG. 2. — Diagram to show the Structure of the Skin.

E.c, epidermis corneous part; E.m, epidermis Malpighian part;
D.c, connective tissue of dermis; /, papilla; gl, sweat gland,
the coils of the tube cut across or lengthwise; dt its duct;_/,
fat; -v, blood vessels; n, nerve; t.c, tactile corpuscle.

of epidermis
were taken off,

the dermis would appear somewhat like coarse velvet be-
cause of its unevenness ; for the prominences or papillae
appear under the microscope, in a cross-section of the skin,

ELEMENTS OF PHYSIOLOGY

buried beneath the cells of epidermis, like a tiny moun-
tain range. As the epidermis fills up the valleys between
them, the papillae do not show plainly on the surface
of the skin. However, on the palm of the hand and
the fingers, where the papillae are especially numerous,
they are crowded into rows, their
position being shown by the paral-
lel ridges seen on the epidermis of
the palm. Within the papillae are
found the ends of nerves and loops
of small blood vessels called capil-
laries (Figs. 2 and 3).

The cells of the epidermis which
lie next to the dermis are living cells.
They are kept alive by nourishment
brought by the watery portion of
the blood in the blood vessels of the
neighboring papillae. These cells
are, therefore, growing cells, and
when they grow to a certain size,
each cell subdivides into two. (The
way in which the cells form new cells
will soon be studied in another

FIG. 3. — Diagram of Epi-
dermis and Upper Part of
Dermis.

Showing nerve, «, and tactile cor- chapter.) This multiplication of the

pu.cle, t.ct or organ of touch; jj M th epidermis tO

also sweat tube, d.

increase greatly in thickness, were

not the outer cells constantly worn away by friction. This
more easily happens as the outer cells are dead cells. The
new cells forming beneath push them so far away from
the dermis, that nourishment from the blood no longer
reaches them, and they die.

By this constant loss and renewal, the body always
has a comparatively new outer skin. Even on the scalp,
which is partly protected from friction, the flat dry cells
are constantly coming off. If there is much oil on the

THE SKIN

scalp, the cells stick together and form flakes called
dandruff.

5. Organs in the Dermis. — The tough, flexible sheet
called the dermis is called by what other name ? Lodged
among its fibers and supported by them (Fig. 2) are
(i) a fine network of blood vessels; (2) a fine network
of nerves; (3) several

million sweat glands;
(4) a great number of
oil glands. Suppose
you were to stick a
pin into the true skin.
You would find evi-
dence that you had
wounded which two
of these possessions
of the true skin ? Are
they so numerous that
you could penetrate
the skin anywhere

without Striking FIG. 4. — Coiled End of a Sweat Gland, Epidermis

them? You learned

that the dermis is

composed chiefly of

fibers, and that the epidermis is composed of cells.

cells are very simple and are called epithelial cells.

6. The Sweat Glands, or perspiratory glands (Figs, i
and 4), are little tubes, lined with epithelial cells, which
pass through the epidermis and down into the dermis.
The tube is coiled into a ball in the true skin, where it is
surrounded by a network of capillaries. Its course through
the epidermis is spiral like the turns of a corkscrew. Its
opening on the surface is called a pore. The coiled part
is supplied with nerves which stimulate the cells to secrete
the perspiration. The cells obtain their supply of material

not shown.

, the coil; b, the duct; c, network of capillaries, inside
of which the gland lies. Does the sweat gland lie in
the skin or beneath the skin? (See Fig. i.)

These

6 ELEMENTS OF PHYSIOLOGY

from the blood so freely furnished them. This supply
is controlled by the nerves which regulate the size of the
arteries leading to the skin. The sweat glands take up
water and various other substances from the blood and
pour them out upon the surface of the true skin. The
water evaporates, but the salt and other solids in the per-
spiration are deposited on the skin ; just as salt will not
evaporate from the ocean, and as solids form in the bottom
of a kettle of boiling water. Usually the amount of per-
spiration from each gland is so small that it evaporates,
or is dried up by the air, as soon as it reaches the surface, and
hence does not become visible. On this account it is called
insensible perspiration ; it becomes sensible perspiration
when it is formed rapidly in warm weather or during vigor-
ous exercise. It does not evaporate so quickly in a moist
atmosphere ; and those who live near the seacoast or in
rainy regions show more perspiration than those who live
in dry regions, although the former may not perspire so
much. The amount of perspiration averages about one
and one half pints per day. In the study of physics, we
are taught that the evaporation of even a small amount
of water, as from a teakettle, uses up a large amount of
heat. Hence, perspiration is very effective in cooling the
body.

Why is humid weather in summer so oppressive and
disagreeable ? Is the skin more active in throwing off
impurities in winter or in summer ? The mucous membrane
is a kind of inner skin, lining the nose, throat, and all
inner passages to which air has access. In case of need,
when the skin fails to act and ceases to throw off the usual
amount of impurities, the mucous membrane may become
swollen with blood and throw off impurities in the form
of phlegm and mucus. Such a condition is called a cold.

7. The Number of Sweat Glands. — Count the sweat
glands shown in Figure 5. This row is one half inch long.

THE SKIN

Skin from the Palm
of the Hand, natural
size.

i, epidermis ; 2, papillae ;
3, dermis ; 4, subcutane-
ous tissue and sweat
glands.

To get the number in one square inch, multiply by itself

the number in a row one inch long. There are about

2,400,000 sweat glands in the entire body. They are most

numerous in the palm. If a sweat

gland averages one fourth inch in length,

how many miles would they extend if FIG. 5. — section of the

placed end to end ?

8. THOUGHT LESSON. Anatomy and
Physiology of the Skin. — i . What
fraction of an inch in thickness do you
judge the skin on the back of the hand
to be ? (A fold shows double thickness.)

2. Feel and observe the skin, and write five qualities
possessed by it.

3. What evidence have you ever had that the skin has
two layers ?

4. How long will a pair of kid gloves last ? What does
this suggest about the skin ?

5. State a fact which shows that the skin gives out
offensive substances.

6. State -a fact which shows that the skin is a protection.

7. State a fact which shows
that the skin is a regulator of
temperature.

8. Are wrinkles a sign that
the skin is too tight or too large
and loose for what it covers ?

9. The loss of what tissue
causes wrinkles ?

9. Hair. — Sometimes a pa-
pilla, instead of being on the
surface of the dermis on a level with other papillae, is at
the bottom of a pit or bag called a follicle (Fig. 7). A
column of epithelial cells forming a hair grows from this
papilla, and the papilla is sometimes called the root of

FIG. 6. —Surface of the Palm,
magnified.

Showing ridges and pores, or openings,
of the sweat glands.

8

ELEMENTS OF PHYSIOLOGY

the hair. A hair, therefore, grows from the top of a
papilla which stands in the bottom of a pit in the true
skin. The outside of the hair is formed of colorless, over-
lapping cells (Fig. 7). The hair
„ is pithy in the center and contains

l^flHB™ pigment cells. In old people, the
£:v^ pigment is replaced by air, and the

mj * hair turns white. The only point

I w, ^ at which the cells of the hair, and

therefore the hair itself, are living
and growing is at the top of the
papilla, deep down in the follicle
(Fig. 7). From this it is easy to
see that the common notion that
cutting off the ends of the hair,
either by shaving or trimming with
scissors, causes it to grow faster
and stronger, is erroneous. It
may stop the splitting of hairs and
thus prevent the wearing away of
the hair. Of course when the hair
or beard is short, its growth is
more noticeable. Long hair seems
by its weight to give exercise to
minute muscles in the skin and
strengthen the flow of blood, thus
FIG. 7. -A Hair in its Follicle, adding to the vigor of the hair.
^^h.tS^^ The cut end of a hair is nearly
cst portion of ths hair growing round in the straight-haired races,

on the papilla z ; a, cuticle of t ...

hair; e, cavity of hair follicle; as Indians and ChinCSC J it is OVal

ft epidermis of follicle corre- - . . j , . j

to «,, the epidermis in the wavy-haired white race, and

S'A-^SiS flattened stm more in the kinky-

k, dermis of foiiicie correspond- haired negro race. Which races

ing to dermis, /, near the surface ; . 1-1

k, mouths of sebaceous or oil have black hair ? In which races
*' h°rny CpidermiS at is the color of the hair variable ?

THE SKIN

10. Hair is very durable ; that found on Egyptian
mummies has remained unchanged through several thou-
sand years. It is elastic and is said to stretch one third
of its length without breaking. Find out whether this
is true by attaching weights to a hair. Hair absorbs
moisture readily, and for a time its length is considerably in-
creased thereby. Each hair follicle has fine muscles con-
nected with it. Cold or fear may cause the muscles to
contract and the hairs, which are usually in a slanting posi-
tion, to stand erect. This causes the

hair to afford a better protection to the
animal from cold or blows. " Goose
skin," which occurs if a cold bath is
unduly prolonged, is caused in the
same way ; but the hair on the human
skin is so fine that the goose skin
avails little against cold.

11. The Oil Glands, or sebaceous
glands, are small, irregularly shaped

FIG. 8. — Piece of Human
Hair, magnified.

Cavities Which Open intO the little A, seen from the surface. B, in

section, c, cuticle; m, pith,
the air having been expelled by
Canada balsam.

pits from which the hairs grow (Fig.
i). A few oil glands open directly
upon the surface. They are lined with epithelial cells.
The cells deposit a kind of oil, which flows out of the
mouth of the glands, renders the epidermis flexible and
less penetrable by water, and prevents it from drying out
by evaporation and cracking open. It is also the natural
" hair oil," for softening the hair and keeping it from
becoming brittle. The oil glands of the center of the face
are especially large and numerous. When their mouths
are stopped by dirt, they become distended with oily mate-
rial and are called blackheads. Oil glands are absent from
the soles and palms.

12. The Nails, as well as the hair, are a growth of the
epidermis ; and like the epidermis, only the lowest cells,

10

ELEMENTS OF PHYSIOLOGY

The skin covering the base of that the nail is renewed in

the nail is cut back.

four months.

near their roots, are alive and receive nourishment. The
root of the nail is in a kind of groove or fold of the true
skin (Fig. 9) at the bottom of which papillae are very
numerous. The nail may be regarded as a very wide, flat
hair. The nail grows not only at its
root, but along its bed which is of true
skin (Fig. 10). Hence, its thickness
increases as it approaches the tip. If
the epidermis is pressed back at the
root, the nail may not be perfectly
nourished, and a white speck or flaw
is formed, which travels slowly along
FIG. 9. — End of Finger, with the growth of the nail. It is said

three or

If you note the date of
the appearance of a scar at the base of the nail and note
when it has traveled to the tip, you can find whether this is
true. Find whether or not a nail is transparent, by looking
through the tip of the nail, held up to the light. The
nails stiffen the ends of the fingers
and aid in handling small objects.
Can you pick up a pin without
using the nails ? Corresponding
organs in the lower animals are
claws and hoofs. The epidermis
forms also the scales, feathers, and
horns of the lower animals.

13. The papillae over a small
area, when the epidermis is weak,

sometimes become overgrown, so that they project above
the skin, and form a wart. If it is burned away with
acid, the epidermis will grow over the place. Why is a
wart rough ? How does it differ from a mole ? Which
is more likely to increase in size ? Which has more pig-
ment ? Which contains hairs ? When the epidermis is

FIG. io. — Section of Nail and
Parts Beneath.

I, 2, 4, horny layer of cuticle, con-
tinuous with 3, the nail; 9, 12,
dermis.

THE SKIN II

broken so that the true skin is exposed, the epithelial cells
at the edge of the break usually produce new cells to cover
and heal the opening. But if they do not form new cells,
the true skin sprouts through the opening, forming proud
flesh, which must be scraped off or cauterized before the
epidermis can complete the healing. In the case of a
blister, the lowest cells of the epidermis are not removed ;
hence the epidermis is readily renewed. Sometimes super-
fluous hair grows on the upper lip of a lady, on moles,
or on unusual parts of the face. To remove this hair
so that it will not grow again, the papillae at the bot-
tom of the follicles must be destroyed. This is no easy
matter. Numerous " infallible " remedies are advertised,
but the only effective way is by means of the electric
needle, a needle which transmits an electric current.

14. THOUGHT LESSON. Hygiene of the Skin. — i. What
is lacking in the skin when it cracks or chaps ? How could
chapping be prevented in another way than by using
cream, etc. ?

2. Why does the skin chap in cold weather more often
than in warm weather ?

3. How does perspiration cool us?1

4. Why do we perspire more freely when we exercise ?

5. Why do we perspire more freely when we are
warm ?

6. Is it more necessary for mental workers to bathe
often, or to change their clothes often ?

7. Which is more necessary for physical workers ?

8. Do you know of persons who burn their hair with
hot irons ? What is the effect upon the hair of repeated
scorching ?

1 Do not try to answer this unless you have studied elementary physics. A
knowledge of that subject will enable you to understand why wetting the feet
even with warm water causes colds more quickly than a draft of cool air upon
the feet.

12

ELEMENTS OF PHYSIOLOGY

FIG. ii.

A, typical structure of a mucous
membrane with two layers of epi-
thelial cells, a, 6; c, the connec-
tive tissue beneath, with e, blood-
vessels, and ft connective tissue
cells.

B, the same with one layer of cells
resting on 3, the so-called base-
ment membrane.

FIG. 12.

A simple tubular gland with blood-
vessel.

FIG. 13.

A tubular gland dividing.

FIG. 14.
A sac-like gland.

Diagrams to illustrate the Struc-
ture of Glands.

15. The Mucous Membrane. —

Epithelial cells form not only the
epidermis to cover the body exter-
nally, but they form also a lining
for the interior cavities of the body.
Any interior cavities to which air
has access, as the mouth, stomach,
and lungs, are lined with one or
more layers of closely packed epi-
thelial cells called mucous mem-
brane. Any cavities from which
the air is cut off, as the heart, are
called serous cavities, and have a
lining of epithelial cells forming
what is called a serous membrane.
These membranes secrete a lubri-
cating fluid. The fluid formed by
the mucous membrane is called
mucus. The line where the epi-
dermis and the mucous membrane
of the lips join can be plainly seen,
as the latter membrane is so thin
that the color of the blood shows
through it. Mucous membranes
are so smooth and their cells are so
tightly packed that they are harder
to cut than the skin, notwithstand-
ing they are very thin.

16. Glands (Figs. 11 to 17) are
always lined with epithelial cells.
Glands are cavities in the body,
usually bag-shaped or tubular,
whose walls secrete fluids which
are of various uses in the body.
The gland cells make use of the

THE SKIN

various chemical substances in the blood, so that one gland
secretes oil, another perspiration, another saliva, etc. The
kidneys are important glands which resemble some of the
glands of the skin in that they secrete injurious substances
that must be removed from the system. Secretion is the
name given the various fluids formed by glands. Excre-

FIG. 15.

A divided saccular gland with duct, d.

FIG. 16.

A similar gland more divided.

FIG. 17.

A racemose or branching gland, part only
being shown.

More Diagrams to illustrate the Structure of Glands.

tion is a secretion of harmful substances to be removed
from the body.

17. Secretion is not simply a process of soaking or sift-
ing through. The walls of the glands are made of cells.
The cells, those wonderful little bodies which we shall study
more carefully in another chapter, obtain from the blood
the materials which they secrete. More than this, by the
aid of the nerves, they can regulate the amount of secretion

14 ELEMENTS OF PHYSIOLOGY

independently of the amount of blood circulating around
them, although usually the amount of secretion is greatly
influenced by the amount of blood in the skin (Fig. 2).
Sometimes the skin is hot from the abundance of blood
flowing through it, as during a fever, but it is dry as well
as hot because the sweat glands are not acting. A dog
does not perspire except through the soles of its feet and
through its tongue. Once a curious experiment was tried
upon a dog in which the nerves supplying one foot had
been severed. This dog was placed in a very hot chamber.
Three of its feet perspired profusely ; but the foot which
lacked nerves to control its sweat glands was perfectly
dry. This shows that nervous control as well as heat
is necessary to make the gland cells perform their func-
tions. Sometimes, under the influence of excitement or
fear, a person breaks out in a profuse perspiration, which
is, however, cold, for there is little blood in the skin.

18. Stimulants and Narcotics. — A stimulant is a sub-
stance that is usually an enemy to the welfare of the body;
it irritates and excites when first taken. This is because
of the effort of the system to expel it. After such effort,
the body is weaker and more sluggish than before. This
effect is called the reaction. There is no known stimulant
that does not cause a reaction. A narcotic is a substance
that deadens the nerves; this effect does not come as a
reaction, but begins as soon as the narcotic is taken.
Strychnine is a stimulant ; tobacco is a narcotic. How
alcohol is apparently a stimulant but really a narcotic will
be explained in another chapter. The toper is said to
have a " rum blossom " on his nose. This swollen condi-
tion of the blood vessels of the nose is caused by the para-
lyzing action of alcohol upon the walls of the blood vessels.
The stagnant circulation allows the blood to become purple
with impurities. Coffee-drinking often causes the com-
plexion to be "muddy." Have you ever noticed any differ-

THE SKIN

ence between the skins of those who use coffee and those
who do not ? Tobacco has an effect similar to that of coffee.
The injury that coffee and tobacco do to the stomach and
liver causes the blood to be impure, and the effect of im-
pure blood usually shows in the complexion.

19. The Teeth may be regarded as a part of the skin,
since a tooth, like a hair or a nail, is developed from a
papilla of the true skin. A tooth extends down into a
depression in the jawbone, called a socket, and is held in
place largely by the tightness with which the root, or
lower part, fits into the socket. The visible part of the
tooth is called the crown.

20. Number and Names of the Teeth. — A complete set
of teeth in adults consists of sixteen in each jaw or thirty-
two in all. They

are named accord-
ing to their form
and the uses to
which they are
adapted. There
are eight (Fig. 18)
in each quarter of
the mouth ; and if
the names of the

FIG. 18. — Teeth from One Side of the Lower Jaw

of Man.
i, incisors; z, canine; 3, bicuspids; 4, molars.

eight in one quarter are learned, you know the names
of the thirty-two, since they are designated by the same
names, in the same order in each quarter of the mouth.
Looking, then, at the teeth in one half of one jaw and
naming them in order from front to back, there are two
incisors, one canine, two bicuspids, and three molars.
How many of each kind are found in the whole mouth
(Fig. 18)? The eight in front are for cutting off the food,
and hence are called incisors, or cutters. They have chisel-
like edges. Do the edges of the upper and the lower
teeth usually meet in the mouth, or do they miss each

i6

ELEMENTS OF PHYSIOLOGY

other like the blades of scissors ? The incisors are very
long in gnawing animals (rats, squirrels, etc.). Next to
the two incisors in each quarter of the jaws, comes one
canine, so called because the corresponding tooth in the
jaws of dogs is well developed ; in cats, tigers, dogs, and
other flesh-eating animals, it is suited for tearing. It
has only one root, but that is a long one. Could you
catch hold with your canine teeth so as to use them for
tearing ? Are they sharper than the incisor teeth ? (Use

FIG. 19.

a mirror.) The two upper canines are fancifully called the
"eye teeth," and the two lower, the " stomach teeth." Next
in order behind the canines are the two bicuspids, which
are grinding teeth. Their crowns are broad and they
have two roots. Last of all come the three large grinders,
called molars. Are the grinding surfaces of the molars
smooth or rough ? Are they like or unlike the surfaces
of the bicuspids ? The last molar in each jaw is called
the wisdom tooth, because these teeth do not come until
the person is supposed to have reached years of dis-
cretion. Activity is the law of life, and the wisdom teeth

THE SKIN

Enamel worn
away

Crown

Neck

are so far back in the mouth that they are not much
used ; therefore they do not usually remain so long as the
others,

21. Milk Teeth. — The teeth just described are those
of the permanent set. The first or temporary set of
teeth (Fig. 19) consists of teeth the same in name and
number as those of the permanent set except that the
three large molars in each half jaw,

twelve in all, are lacking; so there
are twenty teeth in the temporary
set (Fig. 19). The milk teeth come
during the first two years of life, and
begin during the sixth or seventh
year to be pushed out and replaced
by the permanent teeth. They are
all gone by the twelfth year. The
milk teeth have much smaller roots
than the permanent teeth. Since
a tooth does not enlarge after it
develops, the two sets of teeth are
a beautiful provision for preserving
the regularity of the teeth as the
jaws increase in size. If a milk
tooth remains so long as to cause
the tooth of the second set to grow

r i .-i r- ,1 i_ 11 FIG. 20. — Vertical Section of a

OUt Of place, the first tOOth Should Bicuspid Tooth, magnified.

be removed.

22. The main part of the body of a tooth is dentine (Fig.
20). The dentine of the teeth of elephants and other large
animals is the ivory of commerce. It is commonly used
on piano keys, fans, etc. In the central part of the den-
tine is a space called the pulp cavity. The soft substance
called the pulp contains the nerves and blood vessels which
enter at the tip of the root. In the socket the dentine
is covered by cement; above the socket it is covered by

c

Fang

i8

ELEMENTS OF PHYSIOLOGY

enamel, a substance harder, denser, and more shining than
the dentine.

23. The enamel is worn off from the top of the crown
between the twentieth and thirtieth years. (If you examine

a person's mouth in whose teeth the
yellowish dentine shows through the
white enamel, you will know that per-
son to be at least how old ?) Although
the dentine is exposed through the
wearing or breaking of the enamel, it
will last for years without decaying, but
it is more likely to
decay than the en-
amel. We should
never run the risk
of breaking the
enamel by sudden
slipping of the
teeth, such as often
occurs when eating
hard candies or
cracking nuts. A
tooth should never
be pulled if it can

be saved by being filled ; for pulling
a tooth means not only the loss of one
tooth, but the end of usefulness of the
tooth opposite to it, and imperfect chew-
in g in that part of the mouth. Losing FIG. 22.— Teeth of a Cow

fed on Slops.

a tooth is equivalent to losing part of Showing ^ Q{ eating

the life. f°°d that requires the use

24. Decay of the teeth is caused ( i ) by

using only soft food (Figs. 21 and 22) which requires no
pressure of the teeth while chewing it ; (2) by particles of
food lodging between the teeth and becoming quickly de-

FlG. 2i.— Teeth of a
Healthy Cow.

THE SKIN 19

composed in the warm, moist mouth; (3) by the collection
of tartar on the teeth (Fig. 23). This is a deposit formed
because the secretion of the mouth is in improper condi-
tion. It affords an inviting soil in which germs may grow
and attack the teeth. (4) Constant nibbling of candy be-
tween meals is a bad habit, as the
sugar may ferment in the mouth and
change to an acid, which injures the
teeth.

25. A toothbrush is more effective
when it is rubbed up and down as
well as across the teeth. A tooth-

. . . FIG. 23. — Human Teeth ;
pick IS as important as a toothbrush. sockets injured by tartar

As a tooth powder, fine precipitated (°n left) ; uninjured (on
chalk is best; it helps to clean the

teeth and destroys sourness due to acids. Do you like
to leave the table with a sweet taste in the mouth ?
Why does chalk injure the skin, although good for the
teeth ?

26. THOUGHT LESSON. The Complexion. — i . Draw
lines under the words which name qualities belonging to
a healthy skin : hard, soft, dry, moist, flexible, elastic,
firm, flabby, smooth, dingy, rough, pink, yellow, pale, vel-
vety.

2. The and the upon the skin keep it from

being dry.

3. These secretions come from the— —and the .

4. The organs that furnish these secretions get their
material from the .

5. What is the best means of improving the circulation
in the skin ?

6. When a pore is so full of dirt and oil that you can
see it, what is it called ?

7. You have considered what makes the skin soft; let
us think what will make it dry and hard. When our

2O ELEMENTS OF PHYSIOLOGY

grandmothers were young, there was no blotting paper.
What did they keep in a cup on the writing desk to dry
the ink with ? Try it.

8. To what similar treatment is the skin sometimes
subjected ? Why do dry powders, hot winds, and over-
heated rooms all have a similar effect upon the skin ?

9. Think of five girls not over twelve years old. How
many of them have healthy skins ?

10. Of the first five grown young ladies that you hap-
pen to think of, how many have smooth, rosy skins ?
How many have dingy, bad complexions ? Have any of
them blotches in the middle of the cheek ? l

11. The skin does not naturally become dry or dark-
colored with age until after middle life. What have the
young ladies done to injure their soft, rosy complexions ?

12. Why are such young ladies not bright?

13. Who is more apt to be sincere in nature, a person
with a clean face and a truthful complexion, or one who
paints and powders? (Is a "white lie" more truthful
than a pink one ?)

A young lady with a very beautiful complexion was
once asked the secret of it. She said that when she was
a little girl she spent the night with a neighbor's daughter,
and they amused themselves dressing in the clothes of an
elder sister and powdering their faces. On returning
home next morning from her visit, her mother saw some
of the rice powder still around her eyes and punished her
with "a switching," and told her that she must never do so
again. She never did, and grew up with the complexion
of her childhood.

1 The study of physiology cannot be made practical without observing the
effects of violating its laws in daily life. In tracing the effects of tobacco,
overeating, alcohol, ignorant treatment of the skin, overwork, etc., it would
be manifestly improper and ill-mannered to refer to persons by name in a
public place such as a school.

THE SKIN 21

27. Review of Functions of the Skin. — Its chief function,
one of more importance than all others combined, is protec-
tion of the body. The dead outer cells well fit it for this, as
does its peculiarity of becoming thicker where friction is
greater. Savage man's only protection for his head from
the heat of the sun and the blows of enemies, is his hair.

28. Physiologists usually mention the absorbing power of
the skin, but this is very slight ; if it were great, the skin
would lack part of its ability to protect. As it is, man can
handle poisons without harm, provided there is no break in
the epidermis. He can suck with safety the poison from a
bite made by a rattlesnake if there is no raw place or break
in the mucous membrane of the mouth. If the poison
should be swallowed, the stomach would destroy it. Some
volatile poisons like the poison ivy can penetrate the skin.

29. Some writers mention the respiratory or breathing
power of the skin and speak of the skin as a third lung,
but this is a great exaggeration. The skin probably has
about one fiftieth of the breathing capacity of the lungs.
The pathetic story told concerning a child who was gilded
to represent an angel in a pageant held in honor of one
of the popes, may be true. The child is said to have
died in a few hours. Death was probably due to some
poison absorbed in the process of gilding. A man
can live after his body is varnished or covered with a
layer of impenetrable substance. But varnishing the skin
of an animal covered with fur leads to its death from
loss of heat, as the varnish destroys the non-conducting
property of the fur.

30. The skin is an organ of sensation, the nerve fibers
going not only to the papillae, but some of the finer fila-
ments penetrating even among the deeper epithelial cells.

31. The skin is an organ of excretion, the chief sub-
stances excreted being water, salt, ammonia, and a slight
trace of a crystalline solid called urea.

22 ELEMENTS OF PHYSIOLOGY

32. The skin is the chief organ for regulating the temper-
ature. It accomplishes this by means of the perspiration.

33. Clothing does not give heat to the body, but helps
to prevent the escape of bodily heat. Linen and cotton
absorb moisture readily and allow it to evaporate rapidly.
They thus serve, when worn next to the skin, to keep
the body dry ; the evaporation, if very rapid, may chill the
body. Woolen absorbs moisture quickly, but parts with
it slowly, and in the case of those who perspire freely,
the damp clothing next to the skin may conduct away
the heat. But dry woolen contains much air in the
meshes of the cloth ; and as this is a non-conductor of heat,
such clothing is the warmest of all, silk ranking next. In
cold climates woolen should be worn next to the skin, and
should not be laid aside until the heat of summer begins.
In warm climates, like that of the Gulf States, it should not
be worn next to the skin at all, even in winter, unless by
the very delicate, and it is a question as to whether woolen
does not do more harm than good, even to the delicate, as
it relaxes and weakens the skin. If it is worn in such
climates, with the warmth of spring it should be changed
for less relaxing fabrics. White clothing reflects the heat
of the sun ; dark clothing absorbs the sun's heat. Rubber
clothing prevents moisture from penetrating to the body
and also prevents perspiration from escaping.

34. Bathing. — A bath is necessary for cleanliness, once
a week in winter and perhaps daily in summer. Frequent
bathing, if accompanied by the use of soap and friction,
makes the skin too thin and sensitive. A warm bath
should be succeeded by a dash of cold water to overcome
its relaxing effects. A warm bath is more suitable on retir-
ing than on rising ; it is also more suitable than a cold
bath for a person that is much fatigued. A cold bath is
more invigorating than a warm bath, and should be followed
by a reaction or glow caused by the return of the blood to

THE SKIN 23

the skin. The cold water stimulates the heart and lungs
and causes the bather to breathe deeply and vigorously.
A cold bath, if not taken rapidly, may injure a delicate
person more by its duration than by its coldness ; a deli-
cate person may bear a very cold shower-bath if continued
for only a few seconds.

35. THOUGHT LESSON. The Value of Health. — i.
Name five blessings in youth or later in life that result
from good health.

2. Name five unfortunate results of bad health.

3. Name five things that people apparently value more
highly than health.

4. Think of ten grown persons at random. How many
of the ten are in sound health ?

APPLIED PHYSIOLOGY
EXERCISE I

1. Why does the palm of a washerwoman's hand absorb more
water than the back of the hand ? (§ 11.)

2. If a hair is pulled out, what determines whether it will grow
again? (§9.)

3. Why is linen used for towels ? (§ 33.)

4. What causes the hair to " stand on end " when a person is fright-
ened or when an animal is cold ? (§ 10.)

5. Calculate the length of the perspiratory tubes in one square inch
of the palm, if placed end to end. (§ 7.)

6. Why does the skin become roughened and chapped in cold
weather? (See chapter on Circulation.)

7. What color of clothing is best adapted to summer ? To winter ?

8. When is a scar incapable of being affected by freckles or tan?

9. Could a scar on a negro be white ?

10. How may rubber shoes make the feet moist?

EXERCISE H

11. Why does the heat seem more oppressive in moist weather?

12. Which should usually wear warmer clothing, a farmer or a
merchant ?

24 ELEMENTS OF PHYSIOLOGY

13. Which teeth cut like a pair of scissors ?

14. Why is the outer surface of leather smoother than the inner ?

15. How long does it take a spot of indelible ink on the fingers to
wear off ? Of what does this show the rate of change ?

1 6. How may indigestion cause the teeth to decay ?

17. In what respect do patent leather shoes resemble rubber shoes ?

18. Why is baldness more common among men than among women ?

19. How do you account for the location and shape of the bald spot ?

20. When their skins contain the same amount of pigment, a man's
complexion is darker than a woman's, because his blood is darker, since
it contains ten per cent more red corpuscles. Why do women desire a
fair complexion ?

21. Why is a woman's complexion considered beautiful when it is
pink and fair, but ugly when it is pale or sallow ?

EXERCISE HI

22. Did you ever know of a case of loss of health caused by chang-
ing the warm clothing of daily wear for the thin or scanty dress of
a ball or party ?

23. Why should we remove an overcoat or a cloak when we go into a
warm room ?

24. Why is cold water better than warm water for the daily bath ?

25. Should a person wait for a warning such as fatigue, depression, or
chilly feeling before leaving a bath in the sea or an ordinary bath ?

26. Why do healthy persons living along the Atlantic, Pacific, or
Gulf coasts, have softer skins and fresher, rosier complexions than
those who live in the interior of the United States? Why, if they
live in forest regions such as Louisiana and east Texas, rather than in
prairie regions such as west Texas, Kansas, and Nebraska ?

27. Why are the complexions of English people fresher and rosier
than those of people in the United States ?

28. Glass allows the radiant heat of the sun to pass through ; wood
does not. Why are inside blinds appropriate in cold climates but very
unpleasant and inappropriate in warm climates ?

29. Which are healthier, and in better taste for furniture, in the
Gulf States and the West Indies, willow and rattan, or plush and velvet?

30. Show how the wearing away of the outer cells of the epidermis
contributes to the cleanliness of the body.

CHAPTER II
CELLS AND TISSUES

36. The Place of Physiology among the Natural Sciences.
— Natural objects have long been divided for purposes of
study into the Mineral, Vegetable, and Animal kingdoms.
Are any two of these divisions more closely related to
•each other than they are to the third ? Yes, we find that
an animal and a plant resemble each other and differ from
a mineral in that they are both alive. In order to carry on
the mysterious process called life, animals and plants must
have an orderly growth and activity. The parts by means
of which they carry on this activity are called organs ;
and plants and animals together form what is called the or-
ganic kingdom, while minerals form the inorganic kingdom.

37. The science which treats of living things in general
is called Biology. Botany is one of the biological sciences
and treats of plants. Zoology is another branch of biol-
ogy and treats of animals.

38. We may study the body of an animal in two ways.
We may study the structure and forms of its organs ; this
science is called Anatomy, and it may be studied in the
dead body better than in the living animal. Or we may
study the actions or the functions of the organs of the living
animal; this science is called Physiology. It is divided
into Plant Physiology and Animal Physiology. Anatomy
is likewise divided into two sciences.

39. The Study of the Human Body. — The study you
have undertaken is generally, for convenience, called
Physiology ; but Anatomy must also form a part of the study,

25

26 ELEMENTS OF PHYSIOLOGY

since we cannot understand the functions or the actions of an
organ without knowing its form and structure. But if we
go no further than these sciences, we may as well be study-
ing the position of the stars in the constellation of Orion
so far as practical benefit to our lives is concerned. There
is a third science based upon the other two, called Hygiene,
or the Science of Health. It treats of the proper surround-
ings for healthful living, and of the activities of the body
necessary for the perfect performance of all its functions.
It is in Hygiene that Anatomy and Physiology find their
practical application.

40. The study of the human body should give the follow-
ing results : —

1. It should be a means of intellectual training through
the attempt to master its facts, solve its problems, and
comprehend the relations of its parts.

2. It should be a source of pleasure in leading us to real-
ize the wonders of our bodily structure and the wonderful
adaptations of the body to the surrounding conditions.

3. It should give a thorough knowledge of one vertebrate
animal that would greatly aid in studying other animals.

4. It should give knowledge which, rightly applied, would
form a basis for intelligent care of the health. It should
thus be a training in " common sense," which expression
taken in its original meaning denotes "sense about com-
mon things." We see why physiology, if studied thought-
fully, affords a better training in common sense than almost
any other study, when we remember that health is the
commonest of all subjects for observation and conver-
sation, and that every habit and surrounding condition of
life affects the health.1

41. Cells. — While studying the skin, reference was
made a number of times to the cells of which it is chiefly

1 To a person who is destitute of common sense, or who fails to use his
common sense while studying this subject, it may become the occasion of

CELLS AND TISSUES 2/

composed. Before passing to the study of any of the in-
ternal organs, it will be necessary to study more thoroughly
the nature of cells. The unit of structure of animals and
of plants is a minute object called the cell, and each of their
tissues and organs is composed of many cells. The living
substance of which the cell is made is called protoplasm 1
and this name is applied to the cell substance of both
animals and plants. Workers with the microscope over
a century ago found that plant and animal tissues are
composed of little chambers, which they called cells. It
was found later that the liquid in the little chambers is of
more importance than the walls which the protoplasm
builds around itself. The wall was first called a cell;
now we use the word cell for the globule of living proto-
plasm together with its wall, if it has one.

42. Protoplasm. — We should not think because we use
the same name, protoplasm, for the substance forming the
cellular material of both animals and plants, that its
chemical composition is always exactly the same. This
varies in different cells, and is indeed so complex that
no chemist has ever been able to analyze it. The proba-
bility is that it will never be analyzed, as its complexity
seems unlimited. Besides, there is no such thing as dead
protoplasm. As soon as a chemist begins to analyze
protoplasm, it separates into a number of substances. It is
transparent and jelly like, yet under a microscope there

many unreasonable and misleading notions. This is especially the case with
extremists, or with persons who entertain only one idea at a time. They are
unable to assign to each truth its proportionate importance.

These are the persons who chill themselves in order to ventilate, worry
themselves about digestion, make themselves nervous while trying to develop
their muscles, etc. On the other hand, we all know of eases where a person
when young was the weakest member of the family; but who, through an intel-
ligent study of physiology and hygiene, became the soundest and healthiest
one in the family, and outlived those who were at first sound and strong.
1 Greek, protos, first; plasma, that which is molded.

28

ELEMENTS OF PHYSIOLOGY

V

appears an interlacing series of beads and lines (Fig.
26). But there must be some test for identifying pro-
toplasm, or we should never be able to tell organic from
inorganic matter ; animal and plant substance from
mineral. The only distinguishing feature yet known
about protoplasm is that there are always found in it
certain complex albuminous substances that are never
found in inorganic bodies. The white of an egg, also
called albumen, is such a substance.
The power that the cells possess of per-
forming the processes of life depends
upon the presence of these albuminous
substances. The albumin, or nitroge-
nous substance, in protoplasm makes it,
therefore, the life substance, and dis-
tinguishes it from the mineral world.
Nothing in the world besides animals
and plants possesses the power of
growth by converting other material
into its own kind of substance.

43. Difference between Animals and

'"Water

FIG. 24. — Diagram.

The plant taking in carbonic

acid gas, called also car- Plants. — Can you always tell an animal

bon dioxid, the product of ^ n ^ ^ ?

fire and of animal life. By

from a plant ? You say an animal can

means of the sun's energy mQve from pjace to place ; the TCply is,
the leaf builds the carbon

into living forms and gives no, a sponge and many other animals

back the oxygen to the air. . . ,

cannot. You say an animal has nerves
and feeling, but some simple animals are without nerves ;
on the other hand, some plants respond to a stimulus or
irritation, although they never develop special organs
for transmitting the stimulus. It is easy to distinguish the
higher animals from plants ; but in regard to many of the
lowest forms of single-celled organisms, the most learned
biologists find it impossible to say whether they are plants
or animals. The clearest difference between animals and
plants is, that plants get their food directly from mineral

CELLS AND TISSUES

29

substances, while animals must get their food from organic
substances, either from plants or from other animals which
in turn have eaten plants. The plant builds up complex,
unstable substances by means of the sun's
light and heat (Fig. 24). The animal eats
the plant, and these substances are finally
reduced in the body to simple, stable sub-
stances, thus setting free the energy stored
up in the plant. (What is it, therefore,
that indirectly furnishes the energy that FIG. 25. — Diagram of

.. ,./ 5X the Parts of a Cell.

sustains all life ? )

44. A Living Cell has two essential parts : a small mass
or globule of protoplasm, and a still
smaller body in its interior, also consist-
ing of protoplasm, called a nucleus (Fig.
25). There may be two other parts, for
often there is a still smaller body, a dot
in the nucleus, called a nucleolus, and
usually the protoplasm has a wall sur-
rounding it called the cell wall (Fig.
26). Cells are of various shapes and

showing that protoplasm has constitute the substance of all the or-

an intricate structure; in

this case it appears some- gans. The cells are all of the human

what like honeycomb; /,«,.«.« •,-, -,. ,, -,

protoplasm ; n, nucleus ; body that is really alive, the substances
in the body outside of cells not being
considered living matter. A cell may be defined as a tiny
particle of protoplasm containing a nucleus.

FIG. 26. — Diagram of
a Cell.

FIG. 27. — A Cell that is Slender and in the Form of a Fiber.
It is from the muscular coat of the intestines ; /, granular protoplasm around the nucleus, n.

45. Fibers. — In some of the tissues the cells are very
long and slender, and a single cell forms a fiber. A fiber is
stringlike in shape (Fig. 27). Sometimes the fibers consist
of rows of cells or of long, fine branches of cells.

ELEMENTS OF PHYSIOLOGY

FIG. 28. — Cells forming a Membrane.

(Mucous membrane of intestines.) A few cells (dark) that from
secrete mucus are shown.

46. Membranes. — Sometimes the cells lie side by side,
packed closely together, and form a thin skinlike structure,

called a mem-
brane (Fig. 28).
47. The Varied
Life of the Cells.
— Some cells, as
the red blood
cells, move about
place to
place, but always
keep in a definite channel. There is, however, one kind of
cell, called the white blood cell, that can change shape and
pass from one tissue into another (Fig. 29).

48. In having a wall, soft contents, and nucleus, the cells
of the body resemble minute one-celled animals sometimes
found in water. Figure 30 shows the appearance under
the microscope of the ameba, one of these small animals.
The ameba seems to be hardly more than a minute drop of
jelly, yet it can move by pushing out a part of its body.
It can absorb food from a tiny particle by rolling itself
around the par-
ticle (Fig. 30).
Afterward the
ameba pulls it-
self away and
leaves behind the
indigestible part.
If the ameba is jarred or struck, it shows that it has feeling.
It absorbs oxygen and gives off carbon dioxid. When it
attains a certain size, it divides into two parts, which lead
independent lives (Fig. 31). The white blood cells are
more like independent one-celled animals than any of the
other cells. Some animals are larger than others because
their bodies contain more cells, not larger cells.

FlG. 29. — Successive Forms assumed by a Colorless

Corpuscle of the Human Blood.

At intervals of one minute.

CELLS AND TISSUES

49. An Ordinary Animal is a Community or Colony of
Cells. — An animal such as a horse or a man, made up of
millions of cells, may be compared to a colony
or community of one-celled animals. When
a child is born in a community of people, we
cannot tell what part in the
community it is destined to fill.
When a new cell is formed in
the body, by the division of an
old cell into two cells, it may
serve its community as a rail-
road man serves a community
of people, that is, as a red blood
cell, and carry food from place
to place ; or it may be a farmer
cell, that is, a digestive cell, and
convert crude material into sub-
stances ready for use by the
other cells. It may be a senti-
nel and soldier, that is, a white
blood cell, and go to any place
that is attacked by foreign or-
ganisms, such as microbes, or it
may help to repair a break in the
wall, as when the white blood
cells (a kind of "jack at all
FIG QO— The trades") collect in great numbers

FlG 3I _
undergoing Di-

Ameba (as ancj form the white matter seen

seen under a

the pro-
cess are shown.
The nucleus di-
vides as well as the
rest of the cell. The

, < . i r\ i rest 01 iiicL.cn. xiic

high power of around a cut in the flesh, or a mother cell divides
the micro- sore that is healing. It may be in'° two daushter

scope) taking / cells.

food. a carpenter cell, that is, a bone

cell, and help to form the framework or skeleton of the
great house which shelters the community ; and last of
all, it may be a director and guide for^the community,
that is, one of the nerve cells, which correspond to the

32 ELEMENTS OF PHYSIOLOGY

officiate, teachers, and preachers of any ordinary community
of human beings. One man learns to do one kind of work
and can do this better than anything else. Often the
nature of his work can be judged by his appearance: so
it is with the cells. Still, the general structure of all
cells is essentially the same, just as all men are alike in
their plan of structure. Thus the tissues of the higher
animals beautifully exemplify the principle called —

50. Division of Labor. — By this means a community of
men working together can accomplish vastly more than
the same number working separately. Each, learning to
do a few things well, can turn out perfect products of
skilled labor, and by a system of interchange can come to
possess the products of the skilled labor of others. With-
out this the human race could have made but very little
progress and would have remained in the state of savages,
who do not practice the division of labor to any great
extent.

51. In the human body, the several groups of cells
called tissues have divided among themselves the various
physiological processes : the muscle cells are for move-
ment, nerve cells for feeling, gland cells for digestion, etc.
They are thus unlike the ameba, whose one cell carries on
all the functions, unaided by any other cell. Still, in the
body of a higher animal, each cell has many forms of
activity common to the ameba and all other living cells;
it requires food as much as if it lived alone, and its food
is digested and brought to it in a state ready for use ; it
requires oxygen, and the oxygen is separated by special
cells and brought to it purer than that found in air or
water. Cells all have at least sometime in their lives the
power to increase in size, and to reproduce themselves by
dividing just as the ameba does (Fig. 31). In this way, the
tissues grow, and thus they may be repaired if injured
or broken.

CELLS AND TISSUES 33

52. The Tissues. — Sets of similar cells are grouped to-
gether to form tissues. The cells may develop long
branches, called processes or fibers, and may deposit mate-
rial between adjoining cells called intercellular substance.
A tissue consists of a mass of cells built up together,
along with all of their processes and intercellular substance.
A part of the body which has a definite work to do is called
an organ, and each organ consists of several tissues. The
tissues are of many kinds. In order to understand them
clearly and to remember them distinctly, we must learn
them according to their uses in the different organs.

53. What are the chief uses or purposes of our bodies ?
If we consider our life, we shall at once say that our bodies
enable us to perceive, to feel, to think, on the one hand,
and to work, to execute, to exert energy, on the other.
The powers of thinking and doing have two tissues allotted
to them in the animal economy, and these two tissues have
been named by physiologists, the master tissues, while
the remaining tissues, to which are intrusted the protec-
tion, support, and renewal of the master tissues, are called
the supporting tissues. The two master tissues, or those
that have to do with controlling and exerting energy, are
called, respectively, the muscular and the nervous tissues.
They will be treated in a general way in the next chap-
ter, so that their part in the functional activity of each of
the various organs may be understood as they are taken
up in turn. Those organs the chief functions of which
are nervous or muscular will be studied in later chapters.

54. In studying the definitions of the tissues and the
drawings showing microscopic views of them, it will be
well to remember that they are all developed from the
same elements, namely, nucleated cells. Every tissue in
the earlier stages is a mass of such cells packed together.
The cells of one tissue, when mature, resemble one another,
but are unlike those of other tissues.

CHAPTER III

THE SUPPORTING TISSUES

55. Connective Tissue consists of three elements : white
fibers, yellow fibers, and connective tissue cells. The
white fibers (Fig. 32) are not elastic. They form a mesh-
work of bundles running in various directions. The bun-
dles consist of still
smaller fibers which
are fine, long, and
wavy; they run par-
allel in the bundle
and never branch.
Scattered among the
bundles are some
branching fibers,
forming a network ;
they are yellow and
generally much
thicker than the white
fibers, and are called
yellow elastic fibers.

They form the second element in connective tissue (Fig.
32, c). The third element is the connective tissue cells.
They are scattered among the fibers. Each has a nucleus
(Fig- 33) > many of them are much branched and the
fibrous parts ®f the tissue already described are believed
to have been first formed as branches of such cells.

56. This wonderfully strong, though delicate, tissue
(Fig. 34) is found in every organ, binding together and
holding in place the various tissues and cells, thus pre-
34

FIG. 32. — Connective Tissue Fibers.

a, small bundles of white fibrous tissue; b, larger
bundles; c, single yellow elastic fibers.

THE SUPPORTING TISSUES

35

serving delicate tissues like the master tissues from strain
and injury. It is said that if every other tissue were

removed, the connective tis-
sue would still give a perfect
model of all the organs. The
tendons and ligaments consist
almost wholly of it. Leather,
the part of skins that is left
after tanning, is made up of
connective tissue. You have

FIG. 33- -Connective Tissue Cor- already leamed ^ the ^
c, cell; A process ; n, nucleus. skin Consists of nerVCS, blood

vessels, and glands supported

by fibers of connective tissue. In tanning, the more deli-
cate parts are destroyed and only connective tissue is left.

57. Adipose (Fatty) Tissue. — This soft tissue furnishes
cushions for delicate organs like the eye, forms a layer
under the skin, thus rounding

out the form, and storing up
food for the use of nerve, mus-
cle, and other cells. The fat 6~
is first deposited in the form of
minute globules in the connec-
tive tissue corpuscles, or cells ;
these globules gradually in-
crease in size. That fatty tissue
consists of both cells and fibers

, . , . . - FIG. 34. — Connective Tissue.

and is developed from connec- , ,

a, fibers with cells on them ; b, free

tlVe tissue Can be Seen by Study- cells in spaces ; c, yellow elastic fiber ;
T^- o T>I r * • d> blood capillary.

ing Figure 38. The fat is in

the cells, and the cells are lodged in pockets formed by

meshes of the fibers of connective tissue.

58. What part of the tissue of hog fat furnishes lard ?
What does beef fat contain that is not in the tallow?
What is suet ?

ELEMENTS OF PHYSIOLOGY

59. Epithelial Tissue. — Covering the surface of the
body and lining every cavity and tube of its interior, is a
tissue consisting of one or more layers of dis-
tinct cells, forming what is called epithelial
tissue. You learned in Chapter I that from
it the hair and nails are produced. It is per-

haps the simplest of
the tissues, consist-
ing merely of cells
packed closely to-
gether, and united by
a very small amount
of a cement sub-
stance of albuminous
nature. The cells
may be in a single FlG'|^~The
layer, as in the mu- Epithelial ^ at
cous membrane of <A and * • con-

nective and fatty

the intestine (Fig.
28), or in many lay-

FlG. 35. — Connective or Sup- . • •

porting Tissue taken from be- ers, as in the epl-

neath the skin. dermis. No blood

Notice that there is a loose network , •**.!.

of wavy bundles of fibers, also VCSSClS paSS HltO tilC

a network of threadlike fibers^ epithelial tisSUC J the
These fibers were probably formed

by the cells which you see lying cells derive their
in the meshes.

nourishment by ab-

sorbing it from the watery portion of the
blood exuded into the adjacent tissues. The
epithelial tissue grows by subdivision of the
cells of the lowest layer. When the nu-
cleus has disappeared, the cells die and
flatten and become mere horny plates, easily
detached; and thus the outer cells are con-

tissue below.

FIG. 37. — Con-
nective Tissue.
(//), Epithelial.
(7),intheWall
of the Eyeball.

stantly wearing away as you learned when studying the
skin.

THE SUPPORTING TISSUES

37

60. The epithelial structures may be placed according
to their functions, in two divisions. One is chiefly protec-
tive in character ; such as the outer skin, the lining of the
mouth and windpipe, the epithelial layers protecting the
delicate nerves and blood vessels beneath. The other kind
of epithelial tis-
sue consists of

cells that con-
tain highly
active proto-
plasm and are
actively en-
gaged in form-
ing fluids called
secretions, from
food brought
to them by the
blood (Figs, ii
to 17). Such
are the cells of
the salivary
glands, which
secrete the
saliva (Fig.
40); of the
gastric glands,
which secrete
gastric juice

(Fig. 41 ); of the pancreas, sweat glands, kidneys, liver,
etc. This class of epithelial tissue is, therefore, of the
greatest value in purifying the body and in preparing
material to be used in its activities: it is essential to the
growth of sound and well-nourished nerve and muscle.

61. Cartilaginous Tissue. — Some parts of the body
require tissue having something of the rigidity of bones,

FIG. 38. — Fatty Tissue.

ve ^at ce^s> ^e^ together by bundles of connective tissue f\ m,
the membrane or envelope of the fat cell ; n, the nucleus, and p,
remains of the protoplasm pushed aside by large oil drop a.
Magnified 200 diameters.

ELEMENTS OF PHYSIOLOGY

yet capable of bending under pressure. This purpose
is fulfilled by the elastic tissue called cartilage. A piece
obtained fresh from the animal is seen to be covered by a
thin fibrous membrane, which is reddish because it contains
blood vessels. When this membrane is stripped off, the

cartilage shows no signs of red-
ness, that is, it contains no blood
vessels. A thin section of fresh
cartilage appears to the unaided
eye as uniform as a piece of
glass. Under the microscope
we see that it is not so, but that
scattered in its gen-
eral substance are nu-

FIG. 39. -

Lining

cell is rounded and
nucleated (Fig. 43). They are often in pairs,

and in that case adjacent sides are flat ; which

. .
at once suggests that they have ciandCeiis.

been formed by the division of Resting, fuii of

granules, after
activity ; lower

FiG." 40. — Six

one cell. In the growth of car- granules> after

tilage each cell divides into two cel,ls shrunk

0 and contain-

cells. These new cells later on ing few gran-
divide in a similar way, so that
a group of four or eight cells that have
all sprung from one cell may be seen. The
general substance between the cells is de-
FIG i —TWO Positecl by the cells and is called the inter-
Gastric Glands, cellular substance or the matrix.
simple tubular gg. Cartilage may be readily felt in the

glands such as J J

these may be nose (in what portion ?), ears, and windpipe.

ifa It may contain an abundance of the yellow
r °f th° elastic fibers of connective tissue, in which
case it is very elastic, as in the ear ; or it
may have masses of white fibers, and may be unusually

THE SUPPORTING TISSUES

39

connective tissue cells and blood COlttDOSCd. of
vessels. ^

tough, as in the cartilages between the divisions of the
vertebral column.

63. Osseous (Bony) Tissue. — Just as ordinary connective
tissue supports and holds in place the delicate cells and

fibers of the organs, so the bone
and cartilage support the various
complete organs and hold them in
their proper places in relation to
one another. Cartilage and bone
are closely related as to location
and function ; they are also closely
related in their development. For
FIG. 42. — Ciliated Epithelial example, in infancy the flat bones

Cells, which line the Air r . ,, r j -j r j_i_

Tubes. (Cilia are hairiike.) forming the roof and sides of the
a, large cells; b, young ceils;,, skull are soft and flexible, being

cartilage, except a
patch of bone in the middle of each.
As growth proceeds, the bones touch and interlock, replac-
ing the cartilage. If a bone is broken, the new bone, as it
heals, is first cartilaginous and afterward solid. Late in life
some of the ordinary cartilages of the joints change to bone.

64. Periosteum. — A bone usually has its ends coated by
a layer of cartilage. At

the margin of the sur-
face that forms the joint
the cartilage thins out,
and a layer of vascular
("full of vessels'") con-
nective tissue begins
and, extending over the
remaining surface of
the bone, forms a cover-
ing for it, called the
periosteum. This con-
tains the blood vessels which pass into the bone to supply

FIG. 43. — Cartilage. A thin Section, highly
magnified.

m, matrix ; a, group of two cartilage cells; b, a group
of four cells ; c , a cell ; «, nucleus.

40

ELEMENTS OF PHYSIOLOGY

nourishment. It is closely adherent to the bone and may be
removed by scraping. It is sometimes seen as a ragged
margin on the sawed end of a bone fresh from the butcher.
65. The hardest and most compact part of a bone seen
under the microscope shows the following system of open-
ings (Fig. 44): (i) canals, called Haversian canals, run-
ning lengthwise of the bone and containing blood vessels

which extend into them
from the periosteum ;
(2) irregular spaces called
lacuna arranged in cir-
cular lines around the
canals; (3") from the la-
cunae numerous minute
wavy passages called
canaliculi pass inward
to the Haversian canals,
while others pass out-
ward to open into the
lacunas in the outer cir-
cles. The canaliculi

afford PassaSe to minute
blood vessels.

66. The lacunae con-
tain small cells called
bone cells, each having a
nucleus and sending out
fine processes or branches

for some distance along the canaliculi. They receive their
nourishment from the blood flowing through the Haversian
canals, which penetrate to them in their stony prisons,
through the canaliculi. They have for their special form
of activity the building of walls of phosphate and carbonate
of lime about themselves. The walls built by the neigh-
boring cells touch one another, and becoming fused together

FIG. 44. — Bone cut across, highly
magnified.

H, Haversian canals ; /, lacunae, connected by
canaliculi.

THE SUPPORTING TISSUES 41

make the whole bone strong and rigid. Thus the hard, min-
eral part of the bone is deposited by these bone cells and is
nourished by them. The bone corpuscles, we thus see, lie
in the intercellular substance or matrix, in much the same
way that the cartilage cells lie in the intercellular substance
of the cartilage. In bone the matrix consists mostly of lime.

67. Aided by the figures, make a series of drawings
showing the form of the cell in the several tissues. Can
you see that the cell has not only similar parts but also
similar functions, in each of the tissues studied ? Some
cells live only a few hours ; others, as the cells of cartilage
and bone, may live for years.

68. It should be repeated that each organ of the body
consists not of one, but of several tissues. The heart, for
example, is composed principally of muscular, nervous, con-
nective, and fatty tissues ; the eye is formed of nervous,
connective, muscular, and epithelial tissues. The following
list shows the several classes of tissues : —

MASTER TISSUES ( N;™ous Tissues
[ Muscular Tissues

( Connective Tissues

Fatty Tissues
SUPPORTING TISSUES J Cartilaginous Tissues

Osseous Tissues
^ Epithelial Tissues

69. Tissue Building. — As you have learned, all of the
tissues are built, maintained, and repaired by living cells.
Life and health depend upon the proper and continuous
activity of these cells, and anything which aids in this
activity strengthens the body and prolongs life; any-
thing which injures them or interferes with their activity,
impairs the health and shortens life. Growth and repair
of tissue are promoted by sunshine, by fresh air, by drinking
plenty of pure water, by good food, by active and happy
occupation. Weakness and injury of cell and tissue

42 ELEMENTS OF PHYSIOLOGY

result from depriving the body of these conditions. The
only possible way to return to health of the body is to
restore these conditions, and adapt the daily life to them.
The effect of various substances upon living cells may be
watched under a microscope. If bathed with a proper
food substance, the cell is seen to expand and grow and
move more actively. If bathed in an astringent substance
like the tannin of tea, it shrinks and ceases its movements
until revived. If bathed in a liquid to which a small quan-
tity of alcohol has been added, its activity ceases, and
unless the proportion is very small, such activity cannot
be restored. The chemical substances that actually attack
delicate living cells, causing them to shrivel, or decompos-
ing and destroying them, are called poisons. Arsenic de-
stroys the red blood cells. Strychnine attacks some of the
master cells, namely, the nerve cells, and their activity in
attempting to cast off the poison sometimes throws the
body into a spasm. The action of some poisons upon
cells, especially the nerve cells, is called —

70. Stimulation. — This unnatural and exhausting ac-
tivity of the cells in their efforts to free themselves from
poison, is interpreted by some persons to mean that the
poison gives the strength and activity shown in the cells.
The poison does not put strength into the cells, but gets
it out, and honest food alone puts the strength back.
Alcohol hastens the breaking down of cell protoplasm
and lessens the activity of the tissue-building cells. This
is one reason why a person who has been used to alcoholic
drinks recovers less rapidly from an accident or surgical
operation than one who uses none. One of the first ques-
tions asked by a surgeon before operating, is whether the
patient uses alcohol. Tobacco also lessens the activity
of the cells that build and repair the tissues. This is the
reason why men who begin the use of tobacco when young
boys are often poorly developed and stunted in growth.

THE SUPPORTING TISSUES 43

Opium completely paralyzes certain cells. Those poisons
which are used by physicians to regulate the activity of the
cells are called —

71. Drugs and Stimulants. — There are some people who
are so reckless in regard to that delicate organism, the
body, that they are ready to take the place of a physician
and to doctor themselves or their friends with virulent
drugs and patent medicines, and even to make a habit of
using alcohol, tobacco, or opium. The persons who pre-
scribe drugs to their families or friends may say they have
often taken calomel, quinine, patent cure-alls, headache
medicines, etc., and have not been injured. In the case
of some drugs, the most powerful microscope may fail to
show any effect upon the cells; nevertheless, we know a
change has occurred, for it requires more of the same drug
to have a like effect next time. The wisest physician can-
not peep into the secrets of the cells and always discern
whether they are injured. How presumptuous in those
who are not physicians to tamper with drugs ! Such per-
sons err through ignorance or presumption and often do
injury to themselves or their dear ones which lasts through
life. The best physicians give little medicine, especially
when practicing in families of intelligent people who have
the ability and patience to carry out their hygienic direc-
tions. The safe way is to seek the conditions of life named
above. How to do this will be considered in the sections of
this book devoted to hygiene. Sickness is sometimes un-
avoidable. When a person is in bed, it is too late for him
to cure himself by right living alone ; care should be taken
to call a good physician, and his directions should be im-
plicitly followed. Self drugging by the public is considered
by some the most fruitful cause of disease in the United
States. " Mind cure " and kindred ideas often do more by
rescuing victims from poisonous drugs than through their
calming effect upon the mind.

CHAPTER IV

THE MASTER TISSUES

72. A complete animal (or plant) is called an organism.
The cells . constituting it and working harmoniously to-
gether were likened to a human community or town.
Such a comparison helps us to realize how complex and
mysterious is an animal body, and how wonderful are the
processes of life. But the relation between the cells is
much closer than that between the individuals of a com-
munity. A marked difference is that the human being can
move as a whole, can change place in space, can act with
all the organs in the organism working in unison. The
energy stored in the body enables it to do these things,
and the two tissues that chiefly expend the energy and
give us the ability to do things, to act, are the nerve tissue
and the muscular tissue. How is energy, or the ability to
do work, stored in the body ?

73. Oxidation. — We know that this energy arises from a
kind of combustion or slow burning, thus resembling in
its source the energy of the steam engine. That some-
thing besides wood or coal is necessary to a fire can be
shown by shutting off entirely the draught of the stove.
Fire and all other forms of combustion depend upon a
process called oxidation. This consists in the uniting of
oxygen, the active element of the air, with carbon, hydrogen,
and other elements in wood, coal, etc. Bread, meat, and
other foods contain these latter elements. That carbon is
in sugar, for instance, can be easily proved by charring
sugar upon the stove, the charcoal thus produced being a

44

THE MASTER TISSUES 45

form of carbon. Compounds containing these elements
are taken into the body through the digestive organs,
carried around by the fluid portion of the blood, and
stored up in the cells ready for union with oxygen by the
process of slow combustion, or slow oxidation, of which
the activity called animal life seems to consist. The oxy-
gen, on the other hand, enters the body through the lungs
and is carried to the tissues by the red corpuscles of the
blood. Thus is energy stored in the body, the oxygen
being ready to unite with the other elements, giving rise
to heat and motion. The rate and manner of this union
are regulated by one of the master' tissues, the nerves;
while the application of the energy so as to produce
motion is the function of the muscular tissue.

74. The " burning" of food substances in the muscle is
essentially the same process as the burning of coal in the
furnace of the engine, but in the muscle the oxidation
takes place under peculiar conditions not at present thor-
oughly understood, at a temperature of less than 100°
Fahrenheit, while for ordinary combustion a temperature
of several hundred degrees is required.

75. The body resembles a locomotive in having warmth
and motion as a result of the union of fuel and oxygen ;
but it differs from the locomotive, since the intelligent
engineer is an organic part of it, and since the oxidation in
the body is in the presence of moisture, and so gradual
that it is not a true fire accompanied by light. Moreover,
the body can repair itself as it wears out, and the engine
cannot. The energy stored in the body is used more
economically and effectively than any steam engine can
use fuel. This we might well expect from the fact that
the engineer is a part of the engine.

76. Muscular Tissue. — How does the oxidation of food
produce motion ? We learn that the ameba and other
one-celled animals can change their shapes. Many of the

46

ELEMENTS OF PHYSIOLOGY

cells in the body have lost this power, but the muscle cells
retain it. Figure 27 shows a muscle cell of one form.
Figure 45 shows muscle cells of another form. There are
other forms of muscle cells, but they are all alike in the
fact that under certain conditions they get broader and
shorter. Suppose we have a row of cells in a muscular
tissue. Think, for instance, of the muscle in the upper
arm that causes the elbow to bend when the muscle
becomes shorter. It is plain that the shortening of the
whole muscle will be equal to the sum of the shortening
of all the cells in a line extending along
the muscle, and its thickening will be
equal to the thickening of the individual
cells as they lie side by side. But what
makes the muscle cells change shape?
We have found that the food brought
to the muscle by the blood is stored in
the muscle cells in a condition just ready
for union with the oxygen which has also
****• stored in the cells. This union, or
combustion, does not occur continually,
^llt js caused when a certain change
called a nerve impulse comes to the mus-
cle along a nerve fiber; and when the impulse comes,
carbonic acid gas, or carbon dioxid, is formed and the
muscle cells become broader and shorter.

77. Nervous Tissue. — Knowing, as you do, how micro-
scopic the cells are in size, what would you think if you
were told that there are cells in the body that have parts
which extend several feet in length ! There are cells with
branches which reach, for instance, from the backbone to
the toes (Fig. 193). A mass of nerve tissue called the
brain occupies almost all of the skull, and forms the
spinal cord, or spinal marrow. Nerve tissue forms also
the glistening white cords, called nerves, going from the
brain and spinal cord to all parts of the body (Fig. 46).

of the Heart.

THE MASTER TISSUES

47

FIG. 46. — The General Arrangement of the Nervous System (viewed from

behind).
Showing the brain, the spinal cord and the chief nerves that branch from it.

48 ELEMENTS OF PHYSIOLOGY

When eating pork, did you ever see the spinal cord of a hog ?
How large was the cord ? Have you seen a hog's brain
or the brain of an ox? However complicated nerve tissue
may seem to be, it is found to consist of nerve cells and
their branches, called nerve fibers (Fig. 48). Some cells
are arranged in a distinct mass called a ganglion.

78. A nerve consists of a great number of cell-branches
or nerve fibers, just as a number of telephone wires are
sometimes bound together in a cable. Nerve cells grow,
become active and die, like other cells, and like other cells
they consist of protoplasm with a nucleus and nucleolus.
A number of processes branch off from them, some cells
giving off only one or two, others many (Fig. 47). One of
these processes forms a nerve fiber. The axis, or central
part of the fiber, is a continuation of the jellylike proto-
plasm of the cell ; this core is the essential part of the
fiber. The axis is surrounded in most fibers by a sheath
of fatty material (Fig. 48). This is for nourishment
and protection of the axis, and it is this which gives to the
fiber its characteristic ivory-white appearance. The whole
is strengthened by being inclosed in a thin, delicate sheath
of connective tissue. Some of the nerves go to the mus-
cles, and passing between the bundles of fibers, soon divide
into branches, for we have seen that the nerves are bun-
dles of separate fibers. They subdivide in the muscles till
they ultimately send a single nerve fiber to each individual
muscle fiber.

79. How Nerves and Muscles work together. — Suppose
you put your hand on a hot stovepipe or poker; it is
immediately jerked away. How does this wonderful thing
happen ? It is found that the heat of the iron causes a
disturbance in a nerve fiber ending just under the skin of
the finger. This disturbance travels rapidly along the axis,
or core, of the nerve, and is called an impulse. It is not
a visible change, but some influence that travels from par-

THE MASTER TISSUES

49

ticle to particle. It resembles electricity somewhat, but
some physiologists think it is like a wave of chemical
change, running along the nerve faster than a railway
train can run. It reaches a nerve cell in the spinal cord.
The disturbance^ there causes the cell to send out impulses
along its other branches or
fibers. Some impulses are
sent down the arm again to
its muscles, causing them
to contract, and the arm is
jerked away, as we say, by
reflex action, or action with-
out will on our part. Other
impulses go at the same time
to the brain, and we become
conscious of what has hap-
pened. The nerves which
carry impulses to the nerve
cells are called sensory
nerves, or nerves of feeling, and those which carry
impulses from the cells to the muscles are called motor
nerves, or nerves of motion. Nerves transmit impulses,
but do not originate them. An impulse in a nerve can be
excited by pinching, pricking, electricity, a drop of acid,

FIG. 47. —A Nerve Cell.

From the gray matter of the spinal cord,
magnified.

FIG. 48. — Nerve Fiber, highly magnified.
Showing axis (gray), sheath of fatty material (black), sheath of connective tissue (white).

a hot wire, a cold object, or a thought. Reflex action
always occurs on account of some influence from the outer
world, but voluntary action comes from activity in the brain.
80. Suppose you step out of a warm house into a cold
wind. The face immediately blanches or turns white.
Let us see how this is accounted for. There are muscle
fibers in the walls of the blood vessels. The cold air

50 ELEMENTS OF PHYSIOLOGY

excites impulses in the sensory nerves of the face, which
travel to the enlargement at the top of the spinal cord
just at the base of the brain, called the spinal bidb, or
medulla oblongata (Plate VI). Here it reaches a nerve
center which reflects impulses along the nerves that go
to the muscle fibers in the walls of the blood vessels,
causing them to contract, and the face turns white. Thus
we see how closely related are the two master tissues.

81. If we consider that the nerves reach almost every-
where in the body, and that the muscles of the body weigh
nearly as much as all other tissues together, we realize how
important the master tissues are. Let us count up some of
the activities in which the muscles are necessary : swallow-
ing, digesting food, breathing, blushing, writing, walking,
talking, looking, tasting, chewing, frowning, smiling, laugh-
ing, circulation of the blood. There are only a few things,
such as hearing, smelling, and feeling, that can sometimes
be accomplished without muscles. It is now taught by
those who study psychology, or the science of the mind,
that emotions of the mind are always simultaneous with a
change in the circulation of the blood, and that emotion
cannot be felt without a change in the heart or other blood
vessels.

CHAPTER V
SUBSTANCES FORMING THE BODY; OXIDATION

82. Oxidation. — You learned that oxidation is the process
of forming a union of oxygen with some other substance.
When iron oxidizes, iron-rust is formed. When wood de-
cays, the carbon in it oxidizes and carbonic acid gas is
formed. When wood burns, the oxidation is more rapid.
When hydrogen is oxidized, water is formed. For in-
stance, kerosene oil contains hydrogen, and, by burning it
in a lamp, water is formed which collects on the chimney
when the lamp is first lighted, before the glass has become
hot. You learned that animal life seems to be based upon
a process of slow oxidation taking place in the tissues of
the body. Oxygen has great affinity for many substances,
and its union with, them is accompanied by the production
of heat; thus the heat of the body is kept up.

83. Plant and Animal Life. — In plant life there is more
of deoxidation than of oxidation. Carbon when alone is a
solid like coal, charcoal, or plumbago ; oxygen when alone
is a gas. When joined together they make a gas called
carbonic acid gas, or carbon dioxid. The leaves of a plant
absorb the carbon dioxid, and by the aid of the sunlight
the green coloring matter of the leaf separates the carbon
from the oxygen. The carbon remains as a part of the
plant, while the oxygen escapes from the leaves as a gas,
and is ready to burn the carbon in wood or sugar or ani-
mal tissue, and form carbon dioxid again. Just as much
heat, or energy, will be given back in the oxidation as was
furnished by the sun to the plant to enable it, in the leaf,

5'

52 ELEMENTS OF PHYSIOLOGY

to separate the carbon from the oxygen. Thus we see how
animals and plants help each other, and how all nature
forms one harmonious whole (Fig. 24).

84. List of Substances. — The most important solid and
liquid substances of which the body is composed are water,
albumin, fat, sugar, salt, lime, soda, potash. Water, salt,
and lime 'do not oxidize, either in or out of the body.
Their use in the body is more mechanical than chemical.

One ounce of albumin is completely oxidized by one and one half

ounces of oxygen.

One ounce of fat is completely oxidized by three ounces of oxygen.
One ounce of sugar is completely oxidized by one and one fifth ounces

of oxygen.

85. Water. — Water does not oxidize. It is composed of
two gases firmly united : hydrogen and oxygen ; that is,
water is hydrogen already oxidized. Water forms three
fourths of the body. When a solid substance is dissolved
in a liquid so that each remains unchanged in its essential
properties, the result is a solution of the solid in the liquid.
Sugar in water is sugar still ; in fact we can taste sugar
only when it is dissolved. Most solutions can go any-
where that water alone can go. In the stomach the food
is dissolved and taken into the circulation. The blood
containing the food in solution penetrates to the cells,
carrying nourishment and washing away the waste mate-
rial. By means of the perspiration, water takes heat from
the body. About three quarts of water are taken into the
body each day, either alone or in watery foods.

86. Albumin (Proteid). — We learned that protoplasm, or
living matter, differs from inorganic matter in containing an
albuminous material, composed partly of nitrogen. The
other two oxidizable foods, fat and sugar, do not contain
nitrogen. Pure nitrogen is found in the air, but the body
cannot use it in that form, for nitrogen is very inactive when
pure ; when compounded in albumin, however, it gives to

SUBSTANCES FORMING THE BODY; OXIDATION 53

the tissues firmness and strength such as sugar and fats
containing no nitrogen cannot give. Albumin is a very
complex substance which only plants can form. Animals
must get it from vegetables, for it is the essential part of all
living cells. It is similar to the white or albumen of an egg.
Because it turns white when heated, it is called albumen
(Latin albus, white). Pure albumin is hard and brittle, as
the white of an egg is when dried. The albumin of the body
is a solution in from five to twenty-five times its own
weight of water. In the blood it is liquid, in the flesh
it is jellylike, in the connective tissue of the skin it is tough
and strong. Albumin may be hardened or coagulated by
heat ; the albumen of a boiled egg is an example. Coagu-
lation of its albumin destroys the life of a cell. Lean meat,
cheese, animal gelatine, glue, and gluten are forms of albu-
min. About four and one half ounces of pure albumin
per day are necessary to supply the body in winter.

87. Fats. — Fats are smooth, greasy substances that be-
come liquid when heated ; those that are liquid at ordinary
temperature are called oils. Fat is always oil in the living
body and is stored in thin-walled cells in connective tissue
(Fig. 38). Fat is a simple substance compared to albu-
min ; divided in tiny particles or globules, and floating in
water, it forms an emulsion. Milk is an emulsion. No
emulsions are permanent ; e.g. the cream rises in the milk in
a few hours. Fat is a living garment to the body lying
underneath the skin to retain heat, protect from the cold,
and round out the form. It is a cushion for protection and
a store of heat-producing food to be used in sickness or at
any time when food cannot be eaten. About three ounces
of fat should be eaten each day in winter.

88. Starch and Sugar (Carbohydrates). — Starch is
abundant in young plants. As the plant grows the
starch is changed to wood. Fruit while green is chiefly
starch ; but as it ripens, the starch is changed to sugar.

54 ELEMENTS OF PHYSIOLOGY

Starch and the cellulose of wood are different forms of the
same chemical substance. Wood cannot be used in the body,
and starch must be changed to sugar before it can become
a part of the body. Very little sugar is found in the body
at one time, as it is constantly used to produce warmth.
About five ounces of sugar or starch should be eaten each
day in winter, and less in summer and in warm climates.

89. Other Substances. — There are about six ounces of
salt in the human body. We do not give salt to a pet cat
because it gets salt in the flesh it eats ; but we give salt
to the cattle because there is not enough in vegetable food
to supply their needs. Salt gives an agreeable taste to
food and helps to keep the albumin of the body dissolved ;
when salt is not used, weakness results.

90. There are about ten pounds of lime in the human
body. The lime is deposited around the cells of the bones
to give stiffness to the bones.

91. Soda and potash are called alkalies. A substance
which corrodes metals, is sour to the taste and unites with
soda or potash, is called an acid. Vinegar is an acid
substance; when soda is added to it, both are changed, and
the liquid resulting has a flat, bitter taste. Thus acids and
alkalies neutralize each other. Saliva is formed in the mouth
and is alkaline. The gastric juice of the stomach is acid.
The blood is alkaline and performs the function of destroy-
ing irritating acids in the body by neutralizing them.

92. The human body is built up of 13 of the 70 or more
elements. The 13 elements are compounded into substances
which make up the body of a man weighing 1 50 pounds,
in the following proportions : —

92 pounds of water. I pound of carbonate of lime.

21 pounds of fat. 6 ounces of phosphate of magnesium.

1 8 pounds of dry proteid. 2-3 ounces of common salt and chlorid

9 pounds of gelatin. of potassium.

8| pounds of phosphate of lime. 3 ounces of sugar and animal starch.

As much iron as there is in four carpet tacks.

SUBSTANCES FORMING THE BODY; OXIDATION 55

93. THOUGHT LESSON.1 The Tissues. — i. Which tissue
has the largest amount of intercellular material ?

2. Which tissue has no fibers and very little intercellu-
lar material, but is composed almost wholly of cells ?

3. The walls of the arteries contain more of the yellow
fibers of connective tissue than the veins. Which have
more elastic walls?

4. Which tissues have cells without branches? Which
tissues have cells with branches ? Which tissue has two
kinds of cell-branches or fibers ?

5. Does fat accumulate in the body within the cells or
outside of them (Fig. 38)?

6. Which cell has the greatest variety of functions ?
Which cells are the seat of great activity and change ?
Which are moderately active ? Which are very inactive ?

7. Which tissue gives the least evidence under the mi-
croscope of having been formed by cells ?

8. Do adjoining cells have a common wall separating
them, or does each cell have its own wall? Are instan-
ces of both kinds of cells to be found ?

9. Choose a cell and write its " biography."

10. How does a tissue grow? Does a scar on a child,
or a " brand " on a calf or other young animal, enlarge as
its body grows ?

11. State the difference between albumen and albumin.

1 The teacher may require the answers to the questions in this Thought
Lesson to be prepared in writing. In class the pupils should change (but not
exchange) papers, and criticise and correct the answers as they are read aloud
from different papers. The same plan is applicable to the other Thought
Lessons.

PART II. HOW THE BODY IS MOVED
CHAPTER VI

THE SKELETON

94. Animals and their Skeletons. — There are some ani-
mals, such as the slug (a kind of snail without a shell,
Fig. 50) and the jellyfish, that do not possess any hard part
corresponding to a skeleton. Such an animal, if it lives
on land, lies flat on the ground and moves slowly and with
difficulty. Some animals, as the crawfish and the beetle,
have the skeleton on the outside in the form of a crust.

95. Three Functions of the Skeleton and the Three Shapes
of Bones. — Even in man, so capable of self-protection, it
is necessary to have the skeleton, or hard part, to protect
some of the most delicate organs. The bones for this
purpose are flat, as the breastbone and shoulder blade,
the ribs, which protect the heart and lungs, and the skull
bones, which protect the soft and delicate brain. The
muscles by their shortening accomplish very simple and
imperfect motions ; by using the bones for support and as
levers, this motion is changed in rate, direction, and place
of application.

The long bones of the arms and legs, with the fingers
and toes, have motion as their chief function. The ribs are
flat but are the longest bones in the body in proportion
to their size, and enable us to perform the important
motions of breathing. Yet they are classed as flat bones,
for they lack the round shaft and enlarged ends or heads,
which typical long bones have. Even the bones of the

56

THE SKELETON

57

NASAL BONES-"

(SCAPULA) -~

.1 %THE CRANfUM.

'-MALAR (CH EEI<
— SUPERIOR MAXILLARY BONES
-INFERIOR MAXILLARY BONE

SPWAL COLUMN CERVICAL REGION,
^-(CLAVICLE) COLLAR BONE

-HUMERUS

FIG. 49. — The Skeleton.

ELEMENTS OF PHYSIOLOGY

FIG. 50. — The Slug.

instep, palm, fingers, and toes, which are the smallest of
the long bones, have the shaft and
heads.

The many small short bones are
stronger than the long slender
bones, or the flat thin ones. These
bones are called irregular bones.
They are not easily broken and
their chief function is support.

They are found in the spine, the ankle, the wrist, the knee,

and the face. We should remember that the irregular

bones also as-
sist in the two

other functions

of protection

and motion;

also that the

long bones and

the flat bones

are not con-
fined to one

function but

participate in

all three func-
tions (Fig. 49).
96. Another

Use of Bories. —

Recent discov-

erie s have

shown that the

red marrow in

the small cavi-

FlG. 51. — Side View of Skull.

larger bones are named in the figure. The lower jaw is dropped
down. Its socket in the skull is shown in front of the opening of
the ear, au ; z, process of temporal passing to malar, or cheek bone ;
c, one of the condyles or projections which rest in sockets on the high-
est vertebra; tk, hyoid bone, not joined to any other bone, except by
muscles; au, opening of ear ; /, lachrymal bone. A small part of
sphenoid bone is shown ; the main part is at base of skull.

The eight cranial bones are : —
. . r One Frontal (forehead). One Occipital (back and floor).

Spongy TwQ Parietal (sides and roof). One Sphenoid (central floor).

boneS 1S active Two TemP°ral (sides). One Ethmoid (front floor).

in producing the red corpuscles found in the blood.

THE SKELETON 59

97. Number of Bones. — There are 206 bones in the
adult human body. The number of bones is greatest in
childhood and diminishes in old age by the obliteration
of joints. The head has 22 bones in adult life, more in
infancy, and fewer in old age.

98. General Arrangement of the Skeleton (Fig. 49). —
The central part of the skeleton, called the vertebral or
spinal column, forms a firm, but flexible axis. The head
rests upon the top of this column. The ribs are attached
at its sides to make the walls of the chest. The shoul-
der girdle rests upon the chest, and the hip girdle is
attached to the base of the spinal column. These girdles
connect the upper and lower limbs with the trunk.
The bones of the head and trunk form the axial skeleton.
The bones of the girdles and limbs are called the ap-
pended skeleton, since they are appended to the axial
skeleton.

99. The Skull (Figs. 51 and 52) is the cranium, or
casket which contains the brain, and the facial bones.
The arched form of the skull is the best shape for resisting
blows and pressure. Its bones are so firm and hard that
bullets sometimes glance from it. The occipital bone
curves under at the back of the neck to aid in forming
the floor of the skull. It has two projections called condyles
("knuckles") situated just behind its junction with the sphe-
noid (" wedgelike") bone. The condyles fit into depressions
(Fig- 53) m the uppermost vertebra ; thus the head rests and
rocks upon the spinal column. Grasp the neck with both
hands so as to hold it motionless and stiff, and find
whether the head rocks forward and backward, or side-
wise. Between the condyles is a large opening through
which the spinal cord goes from the brain.

Of the eight cranial bones, how many are in pairs, and
how many are not ? Those in pairs are located at the
sides of the cranium. The hair over the temples first

6o

ELEMENTS OF PHYSIOLOGY

turns white, thus reminding us of the temporary nature
of life. What bones receive their name because of
this ?

100. The Bones of the Face are fourteen in number,
twelve being in symmetrical pairs, and two unpaired : the
two malar bones forming the prominences of the cheeks ;

two nasal
bones, small
and slender,
forming the
bridge of the
nose ; two up-
per maxillary
bones, form-
ing the upper
jaw; one in-
ferior maxil-
lary, the lower
jaw ; one vo-
mer, the bony
partition be-
tween the
nostrils ; two
lachrymal

bones in the eye sockets ; two palate bones in the roof of
the mouth ; two turbinated bones in the interior of the
nose (Plate VII). Is any bone of the head movable upon
the others ?

101. The Hyoid Bone, called also the tongue bone, is
U-shaped (this is the meaning of its name in Greek) and
lies in the front of the neck, where it may be felt above the
Adam's apple. Can you move it from side to side with
your hand (Figs. 51 and 129)? Does it feel rough or
smooth ? It forms points of attachment for numerous mus-
cles, the muscular tongue being attached to it above,

FlG. 52. — Bones of the Head.

i, Frontal bone; 2, parietal bone; 3, temporal bone; 4, occipital
bone; 5, nasal bone ; 6, malar bone; 7, upper jaw; 8, lachrymal
bone ; 9, lower jaw (maxilla).

THE SKELETON

61

102. The Vertebral Column. — The

spinal column consists in the adult of
twenty-six bones (Fig. 53). Twenty-
four of these bones have a similar
shape, and each is called a vertebra
(Latin, "that which turns "). The
other two have the names of sacrum
and coccyx. The first seven verte-
brae are in the neck and are called
cervical ("of the neck "). The next
twelve are those to which the ribs
are attached and are called thoracic
or dorsal ("of the back") (see Fig.
49). The next five vertebras are in
the loins or lumbar region and are
called lumbar (" of the loins "). They
are the largest of the vertebrae. The
lowest lumbar vertebra rests upon
the sacrum ("sacred," because this
bone of lower animals was once used
in sacrifice). In infancy the sacrum
consists of five vertebrae ; these begin
uniting at two years of age and com-
plete the union at twenty years. The
coccyx ("cuckoo," from resemblance
to bill of cuckoo), or last bone of the
column, is that part of the skeleton
which in the lower animals forms the
tail. In infancy it consists of four
small bones which later unite into one.
The coccyx is of little use, but the sa-

tTr

FIG. 53. — Spinal Column
(seen from behind).

crum is a highly important bone, since '^te^ST «*"£

to its sides are attached the bones of 7 cervical, 12 thoracic, 5 ium-

- . « • i bar, vertebrae. Do the sacrum

the pelviC arch, by Which the Weight Of and coccyx show evidence of

the body is transmitted to the legs. J™nt| J"" divided in early

ELEMENTS OF PHYSIOLOGY

.8

103. A Single Vertebra consists of a thick disk called the
body of the vertebra (Fig. 54); behind the disk is an
arch, and upon the arch are i

several projections called pro-
cesses. The projection at the
rear is called the spinous pro-
cess, those at the sides are
called transverse processes.
All three serve for the attach-
ment of muscles which prevent
the body from bending
forward under its own
weight. The holes
under the arches of the
vertebrae form a passage for
the spinal cord.

. FIG. 54. — Thoracic Vertebra

104. The first cervical (top view).

Vertebra, Or atlas (Fig. 55), has i, body ; 2, hole which forms part of verte-

, , . , j bral canal ; 3, spinous process; 4, trans-

nO body J it has tWO depreS- verse process ; 5) surface which articulates

sions into which the occipital ££ ^^£^ ^ <• sur'
condyles fit. The head rocks

back and forth (nods) by the condyles slipping in the two
depressions, or sockets, of the atlas. The second vertebra
(Fig. 56) is called the axis. It has a peg in place of a body ;
this peg projects into the hole in the atlas, making a pivot

joint upon which the atlas and
head turn (Fig. 57). When the
head moves around, the atlas
'moves with it, rotating upon the
peg of the axis. Can you find
A ^w out why the atlas received its

FIG. 55. — The Atlas (from above), name ?

105. Between the vertebrae are
elastic cushions of cartilage,
which give flexibility to the spinal column and prevent injuri-

a, sockets for articulation with skull ;
b, peg of axis.with ligament behind it.

THE SKELETON

FIG. 56. — The Axis
(side view).

a, one of the areas for
articulation with atlas ;
6, pivot or peg.

. b

FIG. 57.
a, atlas ; b, axis ; c, pivot of the axis.

a •-

ous jarring of the brain and spinal cord. Otherwise, the head
would receive a great shock whenever one alighted upon the
feet in jumping from a height. The spinal column is

so constructed

as to furnish

strength to sup-
port the body,

to facilitate the

attachment of

the organs to it,

to furnish a safe

passage for the

spinal cord, —

yet while accomplishing these several
purposes, to allow the body to bend without displacing
any of the numerous organs
of the trunk.

106. The Thorax, or chest,
is formed in the rear by the
twelve thoracic vertebrae ; in
front, somewhat parallel to
the spinal column, but ap-
proaching it above, is the
sternum, or breastbone (Fig.
58). Twelve ribs curve
around each side. Each rib
joins one of the thoracic
vertebrae behind. The first
seven pairs directly join the
sternum in front by means
of short cartilages, and are
called true ribs. The next
three pairs, called false ribs,
do not reach the sternum,
but each rib unites to the rib

-10

I -"

FIG. 58. — Bony Walls of Thorax.

a, b, vertebral column; c, sternum; d, costal
cartilages; e, united cartilages of 8th, gth,
and loth ribs; n, 12, floating ribs.

64

ELEMENTS OF PHYSIOLOGY

above by a long cartilage. The last two pairs are called
floating ribs, since the front ends are not attached to a bone
either directly, like the true ribs, or indirectly, like the false
ribs, but rest in the muscular walls of the waist. (Describe
the microscopic structure of cartilage as shown in Fig. 43.)

107. The Appended Skeleton. — This part of the skeleton
consists of the four limbs and the bones which serve to
attach them to the trunk or axial skeleton.

108. Shoulder Girdle. — The arms are attached to the
trunk by the shoulder girdle. This consists (Fig. 49) of

four bones, two on each side,
the scapulae, or shoulder
blades, and the clavicles, or
collar bones. Each shoulder
is composed of a clavicle
( " key," from its resem-
blance to the ancient form
of that article) and a scap-
ula (Fig. 59). The scapula
(a "trowel") occupies the
rear part of the shoulder.
It is a large flat bone, of
triangular shape, and bears
in the end at the angle
of the shoulder a shallow
socket into which is fitted the end of the upper bone of the
arm. The clavicle is a slender bone, round and slightly
curved, which occupies the front of the shoulder, and is
joined at one end to the scapula and at the other to the
sternum. The clavicles can be felt at the right and left
of the base of the neck.

109. The Arm consists of the upper arm, forearm, wrist,
and hand (Fig. 60). The upper arm extends to the elbow
and has only one bone, the humerus. From the elbow to
the wrist is the forearm, formed of two bones, arranged

FlG. 59. — Clavicle, Scapula, and Head
of Humerus.

Disjointed and seen from behind.

THE SKELETON

parallel to each other; the ulna is on the outside, the side
corresponding to the little finger; the

.17171

scap

phi

radius occupies the
inner side, the same
side as the thumb. At
the lower end of each,
a bump may be felt,
the bump on the ulna
being larger. The
wrist is called the
carpus, and is com-
posed of eight small
bones arranged paral-
lel in two rows, four in
each row, running
across the wrist. Next
follows \ho,metacarp2is
("beyond the carpus")
(Fig. 60), or the bones
in the palm of the
hand. The palm is
composed of five long
bones, each serving to
support a finger or
thumb. Each finger
is composed of three
small bones called
phalanges, ("rows of

Jem — -

FIG. 60.— The Arm and soldiers"); the thumb

has only two. The FIG. 61.— Bones of the

Seen from the front. Why W H T o-

do the fingers seem so thumb is more mOV-
long? TII i r Front view.

able than the fingers,

and can be opposed to each of them. The arm therefore
consists of thirty bones; the upper arm has one ; forearm,
two; wrist, eight; palm, five; fingers, fourteen.

66 ELEMENTS OF PHYSIOLOGY

110. The Leg. — The skeleton of a lower limb has a strik-
ing resemblance to that of an upper limb (Fig. 61). The
hip girdle, corresponding to the shoulder girdle, forms
the hip. The hip bones, or innominate ("nameless,"
because they do not resemble anything) bones, are
large, flat, and somewhat semicircular in shape. They
meet in front (Fig. 62), but behind they join the portion
of the spinal column called the sacrum, which separates

FIG. 62. — The Pelvis.

Sac, Sacrum , cocc, coccyx ; acet (acetabulum) , cup for head of femur ; 5LV, fifth lumbar

vertebra.

them and forms, as it were, the keystone of the arch (Fig.
62). Thus is formed a large band of bone inclosing a
basin-shaped space, called the pelvis (" basin "), which con-
tains the bladder and other organs. There is a deep socket
at the side in each innominate bone. This socket is occu-
pied by the round head found on the upper end of the
thigh bone, or femur. The femur is the largest and long-
est bone in the body (Figs. 63, 64).

111. The leg below the knee, like the forearm, is com-
posed of two parallel bones. They are not equal in size,

THE SKELETON

67

like the radius and ulna, however, one, called the tibia, be-
ing much larger than the other, the fibula (Fig. 61). The
E latter bone is merely a brace to the large

tibia, which forms the

joints with the femur

above and the foot below.

There is a bony disk
— D embedded in the great

tendon over the knee,

forming a protection to

the knee joint; this is

called the patella, or knee-
pan. In which direction
"" c can you move the pa-
tella to and fro with the

hand, when the leg is

straight and the heel

resting upon the floor?
112. Like the hand,

the foot consists of

three parts. The tarsus,

or ankle, is formed of

seven bones, although

the carpus has eight.

The metatarsus, like the

metacarpus, is composed

FIG. 63.- Front View Qf fiye bo arranged FIG 64. -Femur (seen

of Femur. from behind).

A fi, i, A t\, parallel to one another.

A, smooth head of bone jn case of a faU} tne femur

for articulating with which SCrVC for the baSC

The tOCS

hipbone; C, shaft;

D and E, rough pro- of the tOCS.

cesses to which mus- 1.1 i

cies are attached ; F, have the same number

would be likely to break
at the turn or angle near
the hip, if there were
not a brace there which
prevents this.

•^ of bones as the fingers,

and have the same name, the phalanges.
How many phalanges are there in the great toe ? The leg,
like the arm, contains thirty bones. How can this be true

68

ELEMENTS OF PHYSIOLOGY

since the ankle has only seven bones as compared with
eight in the wrist ?

113. THOUGHT LESSON. Classification of the Bones.—

Copy and fill out
the following table.
Place after each
name in the first
column the number
of the bones of that
name. This number
should be repeated
in the column to
which the shape as-
signs the bone. For
instance, there are
two femur bones,
" 2 " is therefore
placed in the first
column ; they are
long, therefore " 2 "
is placed also in
the second column.
(See Fig. 49.)

114. Joints.— The
meeting of two
bones is called a
joint. Joints are of
two general kinds,
fixed (or immovable)
and movable. The
hip bones join the sa-
crum by fixed joints.
The most remarka-
ble fixed joints are those in the skull, the bones of which
fit into one another by means of toothed edges, forming

NAMES

No. OF BONES

05

*J

£i

$

No. OF
FLAT BONES

NO. OF-lRREG-

ULAR BONES

Face . . .

Cranium .

Vertebra . .

Sacrum

Coccyx

Innominate .

Rib. ...

Sternum .

Clavicle .

Scapula

Humerus .

Ulna . . .

Radius .

Femur .

Tibia . . .

Fibula . . .

Carpus . .

Metacarpus .

Tarsus .

Metatarsus

Phalanges

Patella . . .

Hyoid . . .

Ear. ...

Totals . .

206

74

59

73

THE SKELETON

69

sac — -

irregular lines known as sutures. A crayon box is so joined,
but the teeth in the wood are much more regular than in
the joints of the skull.

115. A Movable Joint. — Let us take the knee joint, for
example. The two bones which join are the femur and the
tibia. They present to each other an enlargement, or head,
which serves to increase the strength of the joint and increase
the surfaces applied to each other. The two heads instead
of being formed altogether of rigid bone are covered by
cartilage, which by its elasticity and smoothness provides
for the gliding of one bone upon the other. Strong
fibrous bands called ligaments bind
together the ends of the two bones.
Surrounding the ends of the bones,
like a collar, is found a liga-
ment (the capsular ligament)
inclosing the space of the
joint in a closed
sac. This closed sac
is called the capsule.
A thin membranous
sac, called the syno-
via I membrane, lines
the capsule. It se-
cretes a slimy fluid
which resembles the
white of an egg and
is called the synovial
fluid. This lubri-
cates the joint, and
is deposited continu-
ally, but only so fast
as used up in exercise. As the sac has no opening, air is
excluded, and atmospheric pressure aids in holding the
bones in place. The hip joint (Fig. 65) and other joints

fem,-

isc

FIG. 65. — The Right Hip Joint. The Hip Bone
sawed through so as to show the Cup of the Joint.

fern, femur; acet, cup, or acetabulum; caps, capsule;
r. L, round ligament.

ELEMENTS OF PHYSIOLOGY

have the same parts as the knee joint. It is rarely that two
bones put together so perfectly are forced from their
natural places. When this happens it is called a dislocation.

116. The Kinds of Movable Joints are : the ball-and-
socket joint, which allows motion in any direction, as the
shoulder joint ; the hinge joint, which allows free motion
back and forth in one plane, as the knee joint ; the pivot

joint, in which one bone rotates
around another, as the atlas
around the axis, the radius
around the ulna (Fig. 66); the
gliding joints, in which the flat
surface of one bone glides over
the other, as in the bones of the
wrist ; elastic joints (also called
mixed joints), in which there is
one flexible cartilage growing
to both bones, and motion is
allowed by the compression or
bending of the cartilage, as
where the ribs join the sternum.
Elastic joints are sometimes
called mixed joints, because
they resemble both movable
and immovable joints. There
are about 91 hinge joints, 4 ball-
and-socket joints, only 3 pivot
joints, and 43 elastic joints in

the body. The gliding joints cannot be distinctly divided

and numbered.

117. Structure of a Long Bone. — If a long bone is sawed
through lengthwise (Fig. 67), it will be observed that there
is a central cavity containing yellow marrow. (What kind
of steak has a marrow bone ?) We should observe also that
the portions inclosing this cavity are of a dense solid struc-

FlG. 66. — The Bones of the Right
Forearm.

When the hand is supine A, and prone
B; H, humerus; Rt radius; U, ulna.

THE SKELETON

ture, but that the bone is spongy near the ends, — enlarged
for forming the joints. The cavities in this spongy por-
tion contain red marrow. A long bone is hollow, because
a given weight of material has more strength in the form
of a hollow cylinder than in the form of a solid rod. (Does
this imply that a hollow cylinder is as strong as a solid one
of the same size ?)

118. THOUGHT LESSON. Classification of the Movable
Joints. — The table below is to be filled out by the same
plan as in the Thought Lesson on page 68.

NAMES OF BONES
CONNECTED

No. OF
JOINTS

BALL-AND-
SOCKET
JOINTS

HINGE
JOINTS

GLIDING
JOINTS

PIVOT
JOINTS

ELASTIC
OR MIXED
JOINTS

Head -atlas . . .
Atlas -axis .
Rest of spine .
Ribs -vertebrae

I

I
23

Ribs -sternum . .

Ribs -ribs . . .

Clavicle -sternum .

Scapula -clavicle .
Scapula -humerus .
Humerus-ulna. .

Humerus -radius .

Wrist joints . .
Fingers ....
Innominate -femur

X

Femur -tibia . .

Ankle ....

X

Toes

Head -jaw . . .

Total number .

141

4

91

indefinite

3

43

119. Composition of Bone. — Bone is covered with peri-
osteum. This is the name given to the close-clinging
fibrous covering of the bone, composed of connective tissue

ELEMENTS OF PHYSIOLOGY

and blood vessels. If we remove the periosteum from the
surface, the red marrow from the pores, and the yellow
marrow from the larger cavity, we have remaining the true
bony substance. Yet even this is not one substance, but
consists of animal matter and mineral
matter in the proportion of two parts of
the former to one of the latter. The
animal matter is gelatin, like the sub-
stance composing the white fibrous part
of connective tissue. The mineral mat-
ter is chiefly phosphate of lime and
carbonate of lime. Can you describe
the microscopic structure of bony tis-
sue as shown in Fig. 70? The mineral
matter may be removed by soaking the
bones for several days in strong vinegar or
in dilute muriatic acid. The bone is then

flexible but tough.

If a slender bone,

as a hog's rib, has

been used, it can

be tied in a knot;

after the acid has

been washed off, it FlG. 67. - shin-bone

may be preserved <tibia) sawed in two

in dilute alcohol as

a curiosity. The

animal matter may

be removed by

FIG. 68. — Side and Under holding the bone
View of a Vertebra. i . , ,

on a shovel in the

Is it a cervical, a thoracic, or alum- r __ . .. . .. .

bar vertebra? (See Fig. 69.) fire for a Sufficient length of time.

The mineral part remaining is very

light and brittle, and weighs only one third as much as the
original bone, the form of which it still preserves.

along its Length.

2, struts and stays of
spongy bone support-
ing 7, the upper and
lower articular sur-
faces; 3, compact bone
forming the shaft ;
4, marrow cavity ;
6, periosteum.

THE SKELETON

73

120. THOUGHT LESSON. The Spinal 0
Column. —

1. Observe a single vertebra(Fig. 68).
What is the use of the "body "of a ver-
tebra? the arch? the processes?

2. How is the spinal column con- ^
structed so as to allow movement
(Fig. 69), without seriously displacing
any organ supported by it ?

3. In the general form of the spinal
column what shows that its strength
is proportional to the weight to be
supported (Fig. 69)?

4. Do the spinous (or rear processes)
project at the same angle in all parts
of the spinal column (Fig. 69) ?

5. Find, by bending your own body, L.
or by studying Figure 69, what part
allows least motion. Why ?

6. Why are the spinous processes
a source of danger to the spinal cord,
instead of a protection ? (Suggestion :
a blow from the rear, or a fall upon a
process, would cause what part of a
vertebra to break ? )

7. In what region might a blow
from the rear, or a fall, cause the pro-
cess to snap off and leave the cord
uninjured ?

8. If the processes inclined in the FIG. 69. —The Vertebral
neck and the lumbar regions, as in

the thoracic region, what disadvantage

WOUld there be ?

9. Which part of the spinal column
is most easily sprained ? Which next ?

' £ «£

dorsal, or thoracic; L, first
lumbar vertebra ; S, sacrum;

c, Coccyx ; sp, spinous
*' transvcr$e

74

ELEMENTS OF PHYSIOLOGY

HYGIENE OF SKELETON

121. Nourishment of Bones. — If a limb be disused be-
cause of paralysis or long sickness, the bones, as well as
the soft parts, lose in strength and weight. This shows
that the more vigorous circulation which comes with exer-
cise helps to repair the osseous tis-
sue (Fig. 70). The blood vessels
that supply the bones enter from
the inner side of the periosteum.
We thus see why the bone shrinks
away if the periosteum is removed,
and why the surgeon is careful to
leave as much of the periosteum as
possible in the case of bones splin-
tered by accidents.

The animal matter of bones is
most abundant in childhood, and
a child's bones will bend before
they break. If broken, they heal
rapidly. The animal matter is less
abundant in the aged, therefore
the bones are brittle, more easily
broken, and take longer to heal.

122. Broken Bones. — The two
ends of a broken bone should be
brought together in their correct
position as soon as possible, before
inflammation and swelling render
this difficult. Of course a surgeon should be called to set
a broken bone. If the patient has to be carried some dis-
tance, care should be taken to prevent injury to the fleshy
parts by the ends of the fractured bone ; the limb should
be bound with handkerchiefs to a strip of board, or even
to umbrellas or walking sticks, as temporary splints

FIG. 70. — Haversian Canals in
Compact Tissue of Bones,
with their Connecting Cana-
liculi and the Lacunae. Mag-
nified 200 Diameters.

The bone is cut lengthwise. Com-
pare with Fig. 44 where the bone
is shown cut across ; why are
fewer canaliculi cut apart in Fig.
44 than in Fig. 70?

THE SKELETON*

75

123. Dislocation of a joint stretches and sometimes
breaks the ligaments surrounding it, producing inflamma-
tion. This makes examination of it difficult, hence there
should be no delay in procuring the necessary skill and
restoring it to place.

124. A Sprain is an injury due to a sudden wrenching or
straining of the ligaments, as a result of which a ligament
is lacerated or torn from its

fastenings to the bone. A
bad sprain may be more seri-
ous than a fracture, and result
in stiffness or in permanent
weakness. Immediate rest is
necessary. A hot footbath
immediately after spraining
the ankle is sometimes bene-
ficial; careful rubbing, very
light at first and gradually in-
creasing in vigor from day to
day, may shorten the period
of recovery.

125. Acquired Deformities.
— The bones are flexible in
childhood, and, in the case

Of Children at School, Seated A position conducive to round shoulders.

so that the feet hang, instead

of resting upon the floor, the thigh bones may become
bent by the weight of the legs below. Bowlegs are
caused by encouraging children to walk while too young.
The bones of the feet are deformed by tight shoes, " flat
foot " sometimes resulting ; but most often the toes only
are deformed, the joint at the base of the big toe be-
coming enlarged into an unsightly bump. Tight shoes by
influencing the gait may hinder the development of the
body.

FIG. 71. — Sitting with Head and
Shoulders drooped forward at
Work.

76 ELEMENTS OF PHYSIOLOGY

126. Deformities of the Spinal Column come chiefly on
account of the yielding nature of the cartilage. The ex-
tent of the compressibility of cartilage may be realized if
one's height is measured upon rising in the morning and
again at night, when the loss in height sometimes amounts
to nearly half an inch. The cartilages between the verte-
brae are very thick, so as to give flexibility to the spinal
column. This blessing also brings with it a danger of
deformity. If the head is bent forward continuously in
study or work instead of being held up (Fig. 71), the

upper cartilages are compressed in

front, the ligaments stretch, and a

f deformity of the neck may result, caus-

ing the head to project forward.
Working with the desk low in front,
or working upon the ground, may
cause round shoulders.

127. Tight clothing deforms the
ribs, which are readily movable be-

Writing at a desk that is too r , , ., .-p..

high causes one shoulder cause of the long cartilages. The
binding down of the front ends of
the ribs causes posterior curvature of
the spine, with flat chest and round shoulders. Lateral,
or sidewise, curvature of the spine is caused by constantly
carrying the book, satchel, or other weight in the same
hand ; by overindulgence in the valuable habit of horse-
back riding (in the case of ladies) ; by writing at a desk
that is too high (Fig. 72); by hanging the head to one
side.

128. Posterior curvature is caused by habitually bending
over the work, and by slipping down in the seat or desk
(Fig. 73). (It has been called " trying to sit upon the small
of the back.") It is caused also by weakness of muscles,
by wearing shoes with high heels, and by writing at a desk
that is too low. In curvature of the spine, the cartilages

THE SKELETON

77

become V-shaped, and the ligaments stretched. If shoulder
braces are so uncomfortable as to serve as a reminder every
time the wearer drops back into the old position, can they
do good ? If they comfortably support the trunk so as
to take the weight off the muscles, do they do good or
harm ? If it takes some months to compress the cartilages

FIG. 73.

Flat chest, protruding chin, and round
shoulders are produced by slipping
forward on the seat.

FIG. 74. — The Proper Position
in Sitting.

This position is also the easiest be-
cause the weight is poised.

and stretch the ligaments, thus deforming the spinal col-
umn, should one expect to recover natural grace of form
in a few days ? Exercise of the neglected muscles, that is,
opposite muscles, instead of those that were used exces-
sively while acquiring the deformity, is a great aid.
Posterior curvature has been overcome by sleeping on the
back on the floor, or on a hard mattress.

129. The Rule for Correct Position in sitting is to sit back
in the chair with body and head erect (Fig. 74). The
correct position in standing or walking is : chest forward,

ELEMENTS OF PHYSIOLOGY

chin in, hips back. By keeping this attitude in mind and
practicing it faithfully for a few weeks, one can train the
muscular sense to become so accustomed to it that a stoop-

FlGS. 75, 76, 77. — Positions in Standing. (After Mosher.)

In Fig. 75 the weight rests equally upon both legs. This position does not cause deformity,
but soon becomes tiresome, as the legs demand the privilege of working by turns.

In Fig. 76 is shown the best position and the one that should be assumed habitually. One
foot is slightly advanced, and the weight of the trunk can be transferred with ease from
one leg to another. The chest is free to expand.

In Fig. 77, one leg supports the trunk and the other is thrown to one side as a brace. It
is very harmful if the weight is not often shifted. One who has acquired the habit of
dropping upon one and the same leg while at work soon shows the following variations from
the normal : —

If it is the right leg, for instance, that supports the body, the right thigh becomes greater in
circumference, the right hip higher, the spinal column curved laterally with concave side to
the right. The right shoulder is lower than the left, the ribs are crowded together on the
right side, the face becomes slightly unsymmetrical.

ing or crooked position will be uncomfortable (Figs. 75, 76,

77, 78, 79>

130. Nutrition of Bones. — Good food and pure air
brought by a vigorous circulation are necessary to the
health of the bones. Poor or indigestible food, stimu-

THE SKELETON

79

lants, and poisons affect the health and strength of the
bones. Surgeons report cases of fracture of the bones

occurring in persons having

the alcohol habit, where the

bones would not unite by

bony material, but remained

flexible and useless. Indul-
gence in alcoholic liquors,

especially wine, is a very

prominent feature in the

causation of gout, a disease of

the joints. Tendency to gout

may be inherited. Smoking

in boyhood often results in

low and stunted stature.

Rheumatism of the joints, a

diseased condition in which

acids accumulate, affecting

the nerves very painfully, is
FIG. 78 — Tncor- sometimes caused by chronic
rect Position in indigestion, which in turn may

Standing. , •, •, , , r This would be correct

have been brought on by fre- if the body were
quent taking of drugs, by want of exercise,
or by other causes.

131. THOUGHT LESSON. The Joints of
the Arms (Figs. 61 and 66). — The arm is
for grasping and for moving things. In order to perform
this function, the joints are so located and arranged as to
give to the movements of the arm the utmost possible
accuracy, range, firmness, and delicacy.

' i. Determine which of the above four qualities predomi-
nates in different joints, as follows : The ball-and-socket
joint gives - - to the arm movements. The hinge joint
gives to the arm movements. The pivot and glid-
ing joints give and to the movements.

FIG. 79.

not apparently too
strained and stiff.
Compare positions
of head, chest, and
hips in Figs. 78
and 79.

80 ELEMENTS OF PHYSIOLOGY

2. Why is it better to have a ball-and-socket joint at the
shoulder and a hinge joint at the elbow, rather than vice
versa (Fig. 49)?

3. What economy of motion is there in having the
pivot joint in the forearm rather than at the shoulder?

APPLIED ANATOMY
EXERCISE I

1. What in the composition of a bone gives it stiffness? hardness?
toughness? flexibility?

2. Should chairs and benches have straight backs?

3. Why is a chair back that is very slanting often injurious? Why
is a very deep chair injurious, if deep enough for the front edge to strike
the occupant behind the knee?

4. Why does a young child usually crawl before it walks?

5. Which girdle is attached directly to the spinal column? Which
girdle is attached indirectly?

6. Why is the arm so often dislocated at the shoulder?

7. High pillows may cause what deformity?

8. Which three bones in the body are not attached to other bones?
Find twenty-seven bones in the skeleton which are attached to other
bones at one end, but have the one end free (Fig. 49) .

9. Why does a fall not hurt a child as much as it does an adult?

10. Should a young child be urged to stand or walk?

11. What part of a long bone is composed of compact tissue? Of
very porous tissue ?

EXERCISE H

12. Could the neck be broken and death result without breaking
a bone?

13. What would be the result if the ligaments were composed of the
yellow fibers of connective tissue instead of the white fibers (Fig. 32) ?

14. If a child's feet be allowed to dangle from a high seat, what
will be the effect? (See § 125 ; also Chapter VIII, on Circulation.)

15. Is the ''straight front" a healthful position?

1 6. The pivot joint formed by the peg of the axis projecting into the
atlas allows the head to rotate through a large part (about half) of a
circle. Can it nod in any position in that half-circle ?

THE SKELETON 8 1

17. When the palm is turned upward is the radius parallel or crossed
with the ulna? When the back of the hand is up?

1 8. Why should one always sit and walk erect?

19. What are the only two vertebrae whose surfaces move upon each
other? How is motion between the other vertebrae accomplished?

20. In a long bone what is chiefly a storage tissue, saving food for
future use? (§117.)

21. Ligaments are of very slow growth. This accounts for the
tedious nature of the recovery from what kind of accidents ?

22. Observe how many of your classmates sit "slid forward" in
the seat, and report in recitation the result of your count.

23. When the school is marching out, count those who walk with
the head protruded.

24. A bone felon is often caused by a bruise on the bone beneath
the periosteum. Why should it be lanced?

CHAPTER VII
THE CIRCULATION

132. Function and Composition of Blood. — It will be
recalled that the tissues composing the body are made up
of cells ; that these cells are active and must have food ;
that there are several substances necessary to feed the
cells (albumin, fat, sugar, water, salt, lime); that some of
these substances undergo slow combustion in the tissues ;
that this combustion or uniting with oxygen gives rise
to carbon dioxid and other waste substances. How is
the food taken to the cells, how does the oxygen reach
them, and how are the products of combustion removed
before they accumulate and do injury to the delicate cells ?
These three things are done by the circulation of the
blood. We can thus readily see how important the blood
is and how, if the circulation is free and strong and
reaches every part of the body, it is almost impossible for
disease and weakness to occur in the body.

133. Assist, in imagination, in an experiment of great
interest. The artery of a hog or other animal is opened.
As the blood escapes the animal weakens ; at last it suc-
cumbs, and lies motionless, insensible, without breathing,
without any external sign of life. It is only a carcass in
appearance ; and in a few seconds, it will be only a carcass
in reality. Its life is arrested and will soon be finished
for want of combustion in the body excited by oxygenated
blood. Without delay, the extracted blood is injected
again into the veins of the animal. If the experiment is
conducted by skillful hands, you will now assist, as it were,

82

THE CIRCULATION

at a resurrection. The body seems to move, little by little
strength returns, and finally the animal rises. The life has
returned because the vital combustion, not totally extin-
guished, was resumed when the blood reentered the vessels.

134. It is found that the heart stops beating, or beats
very faintly, just before a person faints. What does this
show to be constantly needed that the mind may work ?

Give a proof that blood is present almost everywhere in
the body.

Explain why blushing is a proof of this fact ? What two
kinds of tissue are destitute of blood vessels (Chapter II)?

135. The Problems, the answers to which we are to
study in this chapter, are : the composition of blood, the
reasons for this composition, and how the blood is dis-
tributed to the different cells and tissues.

136. Composition of the Blood. — When seen under the
microscope blood no longer appears of a uniform red
color. It is found to con-
sist of a clear, colorless

liquid called plasma, in
which floats a multitude
of small bodies called cor-
puscles. The corpuscles
themselves are seen to be
of two kinds. By far the
greater number are round,
yellow, and flattened, but
a few, perhaps one in four
hundred, are round, white,
and globular, and larger than the yellow ones (Fig. 80).
The yellow ones are called the red corpuscles, because the
light shining through a great number of them gives the
blood a red color.

137. Reasons for the Composition of the Blood. — That
the blood may flow readily through every little tube, it

FIG. 80.

B, red corpuscles seen from the side ; D, red cor-
puscles, seen on edge, are run together in rows;
G, F, colorless corpuscles.

84 ELEMENTS OF PHYSIOLOGY

must be liquid, hence a large part of it is water. It is the
plasma or watery portion of the blood which transports
the food to the tissues. The plasma is not, then, a simple
but a very complex liquid. The tissues require albumin,
fat, sugar, and mineral food. We should expect the plasma
to contain all of them, and so it does. As we should like-
wise expect, it gets this nourishment from the alimentary
canal. The sugar is in the form of grape sugar, and be-
cause of this, blood or meat containing it is slightly sweetish
in taste. The fat is in the form of minute globules, and
the albumin is similar to egg albumen, but very much
diluted with water.

138. Let us take up another function of the blood. How
does it carry the oxygen ? This gas enters the red cor-
puscles while the blood is in the lungs, and makes them a
brighter red. It is given up to the tissues ; and at the same
time the tissues give up carbon dioxid, which is carried to
the lungs by the corpuscles and the plasma. YtTe liquid
impurities in the tissues are carried by the plasma to the

j skin and kidneys. We see, then, that the

i Jj red corpuscles transport the greater part

of gaseous material, while the plasma
I ^Hak transports the liquids and the solid mate-
mm fl H r^s dissolved m the liquids.

139. What are the White Corpuscles for?

\^&/ -This brings us to a fourth function or

FIG 81 use °f tne blood, a function that has been

i, human blood cor- discovered only within the last few years.

fronfvkwf t fro"* The blood of healthy persons possesses a

biood corpuscles, certain power of destroying germs of dis-

side and front view. •' ° c

Both are drawn to ease which may enter the body; this is

the same scale. - . .

called its germicidal or germ-killing power.
The germs are minute one-celled organisms to be seen
only through a powerful microscope. Some float in air ;
others are found in liquids or solids. Most kinds of germs

THE CIRCULATION

are not harmful to man. For instance, there is a germ
which gets into milk and causes it to turn sour. The
yeast germ, used in bread making, is a microscopic one-
celled plant which obtains its nourishment from sugar.

140. The germicidal power of the blood is believed by
many physiologists to rest, in part at least, in the white

corpuscles. When the flesh

is cut, or when bacteria lodge

in the tissues, these little
scavengers may be seen
collecting at the danger
point in great numbers:
some of the germs are de-
voured bodily by the white
corpuscles : others are killed
probably by substances in
the plasma which were
formed by these little guardi-
ans. In no way is the provi-
sion for our welfare better
shown than by the existence
of these corpuscles (Fig. 82).

141. Experiment on the
Parts of the Blood. — If
some blood from an animal
is allowed to stand in a ves-
sel, it soon becomes a red,
jelly like mass. This change

is called coagulation. If we let the coagulated blood stand,
it gradually separates into two parts, — a light yellow liquid
called serum, which is colored by a few blood cells, and a
semi-solid mass called the clot, which contains most of
the cells together with some threadlike fibers (Fig. 83).
A substance called animal fibrin was in solution in the
plasma or liquid portion of the blood. It has solidified

FIG. 82.— Migration of White Corpuscles
through the Walls of a Vein.

They are shown in different stages of migra-
tion. The red corpuscles remain in the
stream.

86

ELEMENTS OF PHYSIOLOGY

into fibers which by entangling the corpuscles caused the
formation of the clot. The serum, or the portion of the
blood that remains liquid, is composed of water and albu-
min, with traces of sugar, fat, and certain salts. If the

FlG. 83. — Diagram to Illustrate the Process of Coagulation.

I. Fresh. II. Coagulating. III. Coagulated.

(Corpuscles and plasma.) (Birth of fibrin.) (Clot and serum.)

Plasma minus fibrinogen equals serum. Corpuscles plus fibrin equal clot.

water is -boiled away, the albumin is left as a white jelly.
The composition of the clot, serum, and plasma may
be shown as follows : —

COAGULATED I

BLOOD

I Serum

( Blood corpuscles
1 Fibrin

J Water J> Plasma
1 Albumin

LIQUID
BLOOD

CIRCULATION OF THE BLOOD

142. The organ which gives the push or impulse to the
blood and causes it to circulate in the tubes or vessels is
the heart (Fig. 84). The tubes that conduct the blood
away from the heart to the organs and tissues are called
arteries. The tubes through which it returns to the heart
are called veins. The very small tubes that take the blood
from the arteries to the veins where it begins its return
journey are called capillaries. The blood must circulate in
order that it may go to the digestive organs to get food,
to the lungs to get oxygen, and to all the tissues in order to
distribute these things, and to carry away waste materials
to the organs that will free the body of them. Can you
see in your mind the dark color of a piece of beef and

THE CIRCULATION

the lighter color where a fresh cut is made ? Blood
going from the lungs to the tissues is bright red, about
the color of a piece of new beef when the knife cuts into
it. The blood going from the tissues to the lungs is
darker, about the color of the outside of the piece of raw
beef some time after it is cut.

143. The heart is situated in the chest, between the two
lungs. It is a hollow muscle, and has the remarkable
power of contracting and relaxing itself with periodical
regularity. The movement of contraction is called the
systole ; the relaxation is called the diastole.

144. The heart is divided by a vertical partition into
halves (Fig. 84). The right half receives the dark blood

PULMONARY

FIG. 84. — Diagrammatic Section of Heart.

from the body and sends it to the lungs. The left half
receives the bright blood from the lungs and sends it to
every part of the body. Each half is also divided by a
horizontal partition, but unlike the vertical ones, these par-
titions are pierced with openings for communication. The
heart therefore contains four chambers ; the two upper
ones are called auricles, the two lower ones ventricles.
The right auricle communicates with the right ventricle just

88

ELEMENTS OF PHYSIOLOGY

pulmonary
veins

pulmonary
veins

below it, and the left auricle communicates with the left

ventricle.

145. Circulation of the Blood. — From all parts of the

body (except the lungs) the blood arrives at the right

auricle, dark red in color,
and charged with carbon
dioxid, a gas that is unfit
for supporting life. The
blood has come through
two large veins, the supe-
rior vena cava, from the
head, arms, etc. (Fig. 85),
and the inferior vena cava,
from the lower parts of
the body. The first cham-
ber of the heart that it
enters is the right auricle.
The auricle contracts and
presses the blood into the
right ventricle (Fig. 86).

FIG. 85.- Diagram tTthow the Course of the Jt beSins tO Squeeze tO-

Biood through the Heart. gether just around the

The vessels containing impure blood are drawn openings of the VCinS, SO
darker than the others.

that it closes their open-
ings. The blood, owing to this, cannot go back into the
veins, but is forced into the ventricle. The right ventricle
thus filled with blood at once begins to contract. The first
effect of the pressure thus produced is to force blood behind
the flaps of the tricuspid valve, the valve between the auri-
cle and ventricle, consisting of three flaps made of white
fibrous tissue. The blood behind the flaps brings the flaps
together and so blocks the way to the auricle (Fig. 87).
The contraction of the ventricle goes on, and soon the
blood presses hard enough upon the semilunar valve to
open it and go on into the pulmonary artery (Fig. 85);

THE CIRCULATION 89

the pressure from the ventricle soon sends it through the
swollen artery into the lungs (Plates IV and VIII).

146. When the ventricle
has emptied itself, it re-
laxes. The semilunar valve
is composed of three pock-
ets, which the swollen pul-
monary artery fills with
blood as soon as the ventri-
cle begins to relax. The
pockets of the valve are
thus pressed together, and FIG. 87.— The Blood

FIG. 86. — The Right -, , i n i i going through the

Side of the Heart. HO blood flows back into Pulmonary Artery

The blood flowing the ventricle. The auricle to the Lungs.

through the tricus- .. . . .. . Trictisnid valve closed

pid valve into the was relaxing while the ven- Tnsce^fj^e ^s

tricle was contracting, and °Pen-

it is already filled with blood that has flowed in from the
veins. After a short pause, it again contracts ; and the
same action is repeated. More and more blood is thus
driven by the right ventricle through the semilunar valve
into the pulmonary artery, so that the blood which is
already in the artery is sent on through the numerous
small branches and through the multitude of fine tubes
called capillaries ', which go through every part of the lungs.

147. In the lungs the carbon dioxid passes into the air
passages, and the oxygen brought by»the breath goes into
the blood of the capillaries, which changes in color to
bright red. The capillaries unite again to form the pul-
monary veins, which lead back to the heart. We thus
see how the blood is sent from the heart through the
lungs and back to the heart. How is the blood sent through
the body and back to the heart ? We shall find that this
is done by the left side of the heart; that the two pumps
work in unison ; that, in fact, a wave of muscular contrac-
tion starting at the top of the heart passes downward over

90 ELEMENTS OF PHYSIOLOGY

both sides of the heart at once, both auricles contracting
at the same time and then relaxing as the contraction
passes to the ventricles.

148. As we learned, the pressure from the right ventricle
keeps the blood moving through the pulmonary artery, the
capillaries of the lungs, and the pulmonary vein ; it returns
to the heart again, and this time it enters the left auricle.

149. When the left auricle is full, it contracts and drives

m.v.a

MAY

FIG. 88. — View of the Orifices and Valves of the Heart from below, the whole of
the two Ventricles being cut away.

Ao, aorta; PA, pulmonary artery, each with its three cups of the closed semilunar valves
seen convex from below; RAVt opening between right auricle and right ventricle,
surrounded by the three flaps, t.v.i, t.v.-z, t ^.3, of the tricuspid valve with chordae tendineae
between them, to which three cords are tied, taking the place of the papillary muscles;
LA V, opening between left auricle and left ventricle, with the two flaps, m.-v. i, m.v. z
of the mitral valves and chordae tendinae, to which cords are tied.

This figure may be said to show the roof of the two ventricles, with the two great valves
by which the blood enters the ventricles and the two great valves by which it leaves them.
All the openings of the ventricles are upward.

the blood through a valve called the bicuspid (Fig. 88),
or mitral, valve, into the left ventricle. [Mnemonic : the
t(r)i cuspid is on the (r)ight side, the bicuspid on the left.]
The left ventricle (at the same time with its mate, the right
ventricle) then contracts, forcing the blood behind the flaps

THE CIRCULATION

of the bicuspid valve, closing the way back to the left au-
ricle. The pressure of the ventricle opens the semilunar
valve in the mouth of the great aorta, which is the large
artery carrying the blood from the left ventricle. The
aorta takes the blood to every part of the body except the
lungs. It gives off smaller arteries, and the division is
repeated until arteries are supplied to every organ and tis-
sue. In the tissues the arteries
empty into smaller tubes called
capillaries. The aorta, with its
branches, becomes distended with
blood, and as more and more is
forced into it by the left ventricle
at each heart beat, the distention is
kept up, and some of the blood
already in the aorta is forced along
its branches, and the same pressure
forces it through the capillaries and
into the veins (Plates V and VIII).

150. The blood flows slowly
through the capillaries and per-
forms its function of exchanging
substances needed for those used
up. It next goes into the veins on
the return journey to the heart
where it enters the right auricle
again, which was our starting place
in this description (Fig. 89).

151. Review of Circulation. -
The blood comes from the tissues
through the veins and enters the
right auricle, goes through the tri-
cuspid valve into the ventricle, then

through the semilunar valve it enters the pulmonary artery.
Traversing the capillaries of the lungs, it goes by the pulmo-

FlG. 89. — Diagram illustrating
the Circulation.

i, right auricle; 2, left auricle; 3,
right ventricle; 4, left ventricle ;
5, vena cava superior ; 6, vena
cava inferior ; 7, pulmonary
arteries; 8, lungs; 9, pulmonary
veins; 10, aorta ; n, alimentary
canal ; 12, liver ; 13, hepatic
artery ; 14, portal vein ; 15,
hepatic vein. Follow the arrows
and see whether you come
around to the starting point again.

ELEMENTS OF PHYSIOLOGY

FIG. 90. — Transverse Section of Part of the Wall
of an Artery, highly magnified.

, epithelial (endothelial) layer, or inner coat; c, muscular
layer or middle coat; d, outer coat, consisting of connective
tissue.

nary veins, to the left auricle, then through the bicuspid, or

mitral, valve to the left ventricle, thence into the aorta by the

semilunar valve, thence to the capillaries of the system,

thence to the veins, and through them it returns to the heart,

completing the circulation.
152. Structure of

Blood Vessels. — In

order to understand

how the arteries,

veins, and capilla-
ries are adapted to

their work, we will

study their anatomy.

We shall find three

kinds of tissue (Fig.

90) used in their

construction, — epithelial tissue to prevent friction, connect-
ive tissue to give both strength
and elasticity, and muscular tissue
to enable the vessels to change in
size.

153. The epithelial tissue forms
the innermost layer of the vessels.
The endocardium or inner lining
of the heart is formed of this mem-
branous layer, and is continued
throughout the arteries, capilla-
ries, and veins. In these vessels
it is called the endothelium. The
epithelial cellsforming this smooth

FIG. 9i. - Epithelial Ceils forming layer are thm and flat, and serve to

the Walls of Capillaries. J . . . .

Thenucleiandtheontlinesofthecells dimmish friction. The Walls of

may be seen. The forming of the {he capillaries, the Smallest VCSSCls,
thin tubular walls of the capillaries . ... .

is one of the most curious among the COnSlSt Simply Of thlS epithelial

ayerful ^ accomplished membrane (Fig. 91 ). In the small

THE CIRCULATION

93

arteries a layer of muscular tissue is placed outside the
endothelium. Outside of this muscular tissue, and forming
the outer surface of the artery, is a layer of connective
tissue containing both white fibers and yellow elastic fibers
(Fig. 90, also Fig. 32). In fact, some of the yellow elastic
fibers (Fig. 32) are found also in the other coats. The
muscular and connective tissue layers become still thicker
in the larger arteries. So the wall of an artery consists
of three layers: (i) the endothelium ; (2) the muscular coat ;
(3) the connective tissue coat on the outside (Figs. 90 and
92). The arteries are therefore very firm and elastic, and
do not collapse when they are cut, but stand open, and the

-n

A V

FlG. 92. — An Artery and Corresponding Vein cut across.

A, artery ; V, vein ; e.c, endothelial cells ; nt, muscular coat ; c , connective tissue ; «, nuclei
of endothelial cells.

flow of blood through them is unobstructed. The walls of
the veins consist of the same three layers. Their walls are
not so thick as those of the arteries, for the muscular and
connective tissue layers are much thinner (Fig. 92). When
a vein is cut it collapses, that is, the thin walls fall together,
and the bleeding is stopped unless the vein is large.

154. The Use of the Three Coats. — The white fibers of
the connective tissue coat (see Fig. 90) give strength and
firmness to the vessel, and the yellow elastic fibers give elas-
ticity. The muscular, or middle, coat enables the arteries
and veins to change in size, and the inner, or endothelial,

94 ELEMENTS OF PHYSIOLOGY

layer gives smoothness and prevents friction. Why are
these three properties necessary to blood vessels ?

155. Why the Blood Vessels must be Elastic. — The
aorta and its branches are full of blood all the time.
When the left ventricle with its great muscular walls con-
tracts, the blood cannot move forward into the narrow
arteries and capillaries fast enough to make room for the
new supply so suddenly sent out of the ventricle. There-
fore the aorta becomes more than full. If a cup is full, it
cannot become " fuller" ; not so with an artery. The yellow
elastic fibers of its connective tissue allow it to expand as
a rubber hose does under pressure. The first part of the
aorta having expanded to receive the incoming blood, the
portion of the aorta just ahead of the expanded portion is
less tense, or tight, so the stretched elastic fibers contract
and force blood into it, expanding it in turn. Thus a
wave of expansion travels along the blood vessel. It is
called the pulse, and may be most easily felt in the wrists
and neck. The distended elastic walls exert pressure on
the blood in the arteries, and this presses some of the extra
blood out of them into the capillaries. As much blood as
is being pressed on into the capillaries is being thrown into
the aorta by the beat of the heart ; so that during life a
distension is always kept up, and the blood in the vessels
is always under pressure. Although the arteries may get
rid of the additional distension following each heart beat,
there is a normal distension that always remains. It has ex-
isted ever since life began, and will remain until the heart
ceases to beat. The pulse, therefore, is only an additional
distension following the contraction of the ventricle.

You should not think that the muscular layer actively
contracts and helps to send along the pulse ; for the pulse
is simply the passive stretching and contracting of the
elastic tissue ; as a wave travels across a pond when a stone
is dropped into the water. The force of the pulse is

THE CIRCULATION 95

furnished by the heart. What, then, is the purpose of the
muscular layer in- the arterial wall?

156. Use of the Muscular Coat. — The body of an adult
contains about five quarts of blood. We have learned that
the blood supplies the substances needed for the activity of
each organ. If an organ is working, it needs more blood
than usual, which is supplied by the other organs that are
at rest ; they get along with less blood for the time. The
muscular coat of the blood vessels makes this possible.
This coat is usually in a condition of slight contraction,
but the nerves controlling the muscular coat in the blood
tubes of the active organs may cease to act, thus allowing
the muscular coat to relax and the blood tubes to enlarge
under the pressure from the heart, so that the active organs
may obtain the additional supply of blood needed. While
this is happening, part of the pressure in the blood tubes of
the inactive organs is relieved and they become smaller. If
cold air strikes the face, the nerves stimulate the muscular
coat of the blood tubes in the face to contract more strongly
than usual, and the face turns white. This driving of the
warm blood from the face saves heat to the body, which
would be lost if the warm blood remained in the skin.
Thus the amount of blood circulating in any organ is regu-
lated by means of the muscular coat of the blood vessels
and of the action of the nerves upon this coat.

157. The Use of the Inner Coat — We learned that the
inner coat of the heart and blood vessels is made of epi-
thelial tissue, like that which forms the outer layer of the
skin, and the smooth lining of the mouth and other organs.
This lining membrane is very smooth and thus friction is
lessened. The friction, however, is inconsiderable in the
large vessels ; but in the smaller vessels it is greater ; and in
the minute capillaries it becomes of very great importance.
We see, therefore, why it is necessary to have this smooth
coat in the capillaries, although the muscular and connective

96 ELEMENTS OF PHYSIOLOGY

coats are not prolonged into them. It should be stated
here that although the extremely minute size of the capil-
lary tubes increases the friction and the pressure which the
heart must expend in sending the blood through them, yet
their resistance to the blood flow is lessened by their great
capacity. The united capacity of the capillaries is six hun-
dred times that of the blood arteries that supply them.
In the capillaries the blood flows slowly like a river which
flows into and out of a lake.

158. Rate of Flow and Differences of Pressure. — The
velocity of flow is 15 inches per second in the aorta, 3^ of
an inch per second in the capillaries, and about 7^ inches
per second in the inferior vena cava. When an artery is
cut, the blood is thrown out by jerks corresponding to the
pulse, and flows slowly between the jerks because the
arteries are kept over-full and the blood is pressed out by
their elastic walls. The pressure that results from the
arteries being always over-full, likewise explains why the
blood flows constantly from the arteries into the capillaries.
Hence, although the blood is thrown into the aorta at in-
tervals by the beat of the heart, it flows from the arteries
to the capillaries continuously, being only quickened in its
flow by each beat. In the capillaries, owing to the great
friction in the minute passages, there is strong resistance
to the flow of blood, and the great pressure in the arteries
is necessary to send the blood through the capillaries;
a great deal of this pressure is used up in doing so, hence
the pressure beyond the capillaries (that is to say, in
the veins) is much less than the pressure in the arteries.
Enough is left to force the blood part of the way through
the veins ; but it is not sufficient to carry the blood back to
the .heart, for it gives out entirely before the heart is
reached. We shall learn later how the contraction of the
muscles and their squeezing effect upon the veins passing
through or beneath them, aids the heart to move the blood ;

THE CIRCULATION 97

also how the expansion and contraction of the lungs act as
a great pump ; and how these aids, together with changes of
posture, enable the blood to reach the heart again. If
one stands perfectly still for some time, the blood, owing
to its weight and the lack of pressure on the veins, slowly
congests in the veins in the lower part of the body, and
the consequences may be serious.

159. Hence the pressure is greatest in the arteries, less
in the capillaries, and least of all in the veins.

160. How the Amount of Blood flowing through any
Organ may be modified. — We learned that the ability to
do this lies in the muscular or middle coat of the vessels,
and that the muscular coat in turn is controlled by the
nerves. This very important power, therefore, is intrusted
to the two master tissues. The nerves that control the
sizes of the blood vessels are called vasomotor nerves and
are of two kinds. One kind, the constrictor nerves, stimu-
lates the walls of the blood vessels to contract, while the
other kind of vasomotor nerves, called the dilator nerves,
neutralizes or inhibits the effect of the constrictors, and
thus allows the blood tubes to enlarge. The regulation
is involuntary, or beyond the control of the will; for in-
stance, the blood vessels of the brain may become enlarged
and the great pressure there cause a headache, but the
will cannot drive it away. We sit before a fire, and the
face becomes red as the warmth soothes the constrictor
nerves into inactivity ; or the constrictors leading to the
face may become paralyzed by mental confusion and we
blush.

161. Why must the Relative Amount of Blood in the
Different Organs continually change ? — The necessity for
this comes from the fact that if the one and one fourth
gallons of blood were evenly distributed, none of the
organs would be capable of any powerful and effective
action. A person weighing 157 pounds has only 12

98 ELEMENTS OF PHYSIOLOGY

pounds of blood, for the blood is T^ of the total weight of
the body. There is not enough blood in the body to dis-
tend all of the blood vessels at once. The skin alone with
all of its blood vessels distended could contain two thirds
of all the blood in the body. The veins have twice the
capacity of the arteries ; they could contain every drop
of blood in the body. When the brain works, it requires
more blood. When digestion is in progress, the lining of
the digestive organs blushes a rosy red and the digestive
fluids are poured out. During the digestion of a hearty
meal, one will not do his best thinking. When a muscle
is used, the dilator nerves act, the blood tubes in the
muscle become enlarged, and its supply of blood increases
to serve it during its. action. The impulses that run
along the vasomotor nerves arise in the enlargement at
the top of the spinal cord called the spinal bulb. The
part of the spinal bulb that in this way regulates the
caliber of the arteries is called the vasomotor center. It
is constantly sending impulses along the constrictor fibers
so as to keep the muscles of the arteries slightly con-
tracted. The vasomotor center thus keeps a rein upon
the arteries, holding them in a condition of tone, as this
slight contraction is called. Sudden paleness, due to fear,
is brought about by extra strong impulses from the vaso-
motor center, causing the muscular walls of the small arter-
ies of the face to grip the vessels tight and drive the blood
from the face. Alcohol destroys the tone of the blood
tubes. From temporary drinking the face becomes red ;
from habitual drinking the " rum blossom," the purple
swollen blood tubes in the nose, results.

162. How the Flow of Blood through the Whole Body
is regulated. — The amount of blood passing through one
organ may be increased by the vasomotor nerves, but it
is only because the amount going through the enlarged
vessels of that organ has been withdrawn from other

THE CIRCULATION 99

organs whose blood tubes, not being enlarged just then,
afford greater resistance to the passage of the blood than
the dilated vessels afford. But can the total amount of
blood reaching, in a given time, not a single organ only,
but all the organs in the body, be increased ? Yes, for
if the one and one fourth gallons of blood flow faster all
over the body, more fresh blood will reach each organ.
This is accomplished by faster or stronger beating of
the heart. During rapid general exercise, as running,
when the demands of the body are increased, the heart
beats faster, as you have doubtless observed. When the
body in general is at rest, as during sleep, the heart
beats more slowly. Thus the general blood supply is
regulated. But how is the heart itself regulated ? For
these facts show two things : first, that we cannot directly
control it by the will; and second, that there is some-
thing in the body that does control the heart, and perhaps
our wills may influence the beating of the heart indirectly.
The heart, like the blood vessels and the muscles in gen-
eral, is supplied with nerves ; but there is this difference,
namely, that the heart can go on beating without receiv-
ing impulses along its nerves. The heart of a frog, after
being cut out of the body, will go on beating for several
hours if it is kept moist; if it is cut into several pieces,
the pieces will go on beating. It is the property of the
heart muscle to contract, and it will do so as long as its
protoplasm is alive.

163. The nerves going to the heart do indeed carry
impulses to the heart, but this is to regulate the beat of the
heart and not to originate it. A nerve called the vagus
nerve, extending from the spinal bulb to several organs,
goes to the heart ; and gentle impulses which are almost
always passing down the vagus nerve from the spinal bulb,
restrain the heart from too great activity, and are the
chief means of regulating the strength and frequency of

100 ELEMENTS OF PHYSIOLOGY

its beats. When an animal requires a greater supply of
blood, as in running, these impulses for a time cease, and
the heart beat is quicker and stronger (Fig. 202).

164. There are other nerves, called sympathetic nerves,
connected with the spinal cord below the point at which
the vagus branches, that bring impulses to the heart which
are opposite in effect to those brought by the vagus.
These impulses also start in the spinal bulb ; they cause a
quickening and strengthening of the beats (Fig. 200).
Do the vagus nerve fibers or the sympathetic nerve fibers
resemble the whip which a driver uses in driving a horse ?
Which kind corresponds to the reins ? Thus the need of
the body for a greater or less active blood supply is regu-
lated by controlling the rate and strength of the heart
beats. If the nerves are all in order, the heart beats more
slowly when the tissues of the body need little blood, and
more rapidly when the tissues need more food or more
oxygen. But quickening of the heart beat cannot send
more blood through one organ without sending more
blood through all the organs, hence it is not so delicate a
means of regulating the blood supply as the vasomotor
system.

?r^&-

COLEMAN'S ANATOMICAL MANIKIN

JtfUBHBBI

100

PLATE II

PLATE III.

Viscera (front view). For rear
view, see next plate.

t^w-

100

PLATE IV.

Viscera (rear view). Student will find
ducts from the liver and pancreas enter-
ing duodenum together; also, mesen-
teric artery leading to intestines and
portal vein leading from them to liver.

PLATE V.

I

I'm

-., - ,.

|lp
Itiixi

PLATE VI.

PLATE VII.

PLATE VIM

The pupil will trace the circulation of the blood from the body through the right side of the
heart to the lungs; and from the lungs through the left side of the heart to the body; also
trace the portal circulation, from the digestive organs through the liver to the heart.

CHAPTER VIII
THE CIRCULATION (continued)

165. How the Heart is aided in its Work. —The heart
seems to be constantly at work, but such is not the case.
As a matter of fact, the heart occupies nearly as much
time in resting as in working. It works for about half a
second and rests for about half a second. Yet it does
work in a day equivalent to raising a ton of coal nearly
two hundred feet.

166. Increase the circulation in the arm by exercising it
for a few minutes. The veins in the front of the wrist will
then be plainly visible. The skin and walls of the veins
make the blood in the veins appear blue, but it is dark
purplish red. (Did you ever see "blue" blood?) Place
the tip of the forefinger on one of the large veins ; with the
middle finger then stroke the vein toward the hand so as
to push the blood from a portion of it, keeping the two
fingers in place. The vein remains empty between the
fingers. Lift the finger nearer the heart and no blood
enters the vein ; there is a valve above which holds it
back. Lift the other finger, and the vein fills instantly.
Stroke a vein toward the hand, and see the blood cause
the veins to swell up into little knots where the valves are.
(Experiments upon veins are plainest with adults whose
veins are large.) The veins have valves placed frequently
along their course. The valves are pockets made by a
fold in the inner coat of the wall of the vein (Fig. 93).
When you place your hand in your pocket, the latter

101

IO2 ELEMENTS OF PHYSIOLOGY

swells out; but if you rub your hand on the outside of
the pocket from the bottom toward the top, it flattens
down. So with the action of the blood upon the valves
in the veins (Figs. 94, 95). They all open toward the
heart.

167. Suppose a muscle hardens as it contracts and
presses upon a vein which goes through the muscle; the
blood is pressed out of the vein. The
> blood cannot go toward the capillaries,

i- *^ -*H for the valves fill and close when it starts

_ that way ; so it is all pressed out toward
the heart. When the muscle relaxes,
the blood that has been pressed for-
FIG. 93 -Diagram of the ward cannot come back because of

Valves 01 Veins.

H, heart side ; c, capillary the valves, but the valves nearer the

filled. When the muscle contracts
again, the same effect on the blood movement is re-
peated. We see, therefore, that every contracting muscle
converts into a pump the vein running through it, and
when a person works or exercises, many little pumps
are working all over the body, aiding the heart in its
function.

168. This aid makes the blood flow faster and re-
lieves the heart of part of its work, so that it beats faster,
just as a horse might trot faster if half the load were
removed. All of the body gets fresher blood than it
got when the muscles were still and the blood flowed
more slowly. This help comes during active work, just
when the body is demanding more blood and the heart
needs help.

169. Suppose a person engages in vigorous muscular ex-
ertion just after eating. The stomach and the muscles
both demand an increased supply of blood. The muscles
will get it because the valves in the veins will increase the

THE CIRCULATION

103

flow through the muscles, and the muscles are so extensive
and use so much blood that the digestion may surfer be-
cause of the vigorous exercise.

170. Massage. — So effective and necessary is exercise in
aiding the circulation, that some people employ others who
are skilled in the art called massage, to come regularly and
squeeze and knead every muscle like dough. Thus fresh
blood is brought and the removal of waste material from
the tissues is aided. If a boy has so-called "growing
pains " which may come from over-fatigue, or which may
be a light form of rheumatism

from exposure to wet and cold,
his pains can be relieved by
thoroughly rubbing the aching
part.

171. The arteries lie deep
under the muscles near the
bones, and are likewise pressed
upon by muscles, but their
walls are much stiff er than the
walls of the veins. In
many of them in passing
through the muscles have tough,

fibrous sheaths. It is well that the arteries are not
so much affected by exercise, for if they were squeezed
by the contracting muscles, the blood would be pressed
backward as well as forward since they are destitute
of valves, and this would not be favorable to the
circulation.

172. The Lungs aid the Heart to circulate the blood
since when they expand and the air rushes into them, the
blood as well is drawn toward the cavity of the chest,
and when they contract, the blood tends to leave this
^egion.

173. Does the elasticity of the arterial wall furnish

FIG. 94. — Vein
fact, laid open to
show Two
Valves.

FIG. 95. — Valve
in Vein dis-
tended with
Blood.

IO4

ELEMENTS OF PHYSIOLOGY

any force to aid the heart? No. When the arteries
contract as the pulse passes, it is the force of the heart
that is doing it. When you open a door or gate that
is closed by an elastic spring, it is the force furnished
by you to the spring that shuts the door after you
release your hold.

THE LYMPHATIC SYSTEM

174. How the Nourishment gets from the Blood into the
Tissues. — We left the food and oxygen in the capillaries.
How does it get out of them into the tissues ? We found
that the blood flows very slowly in the capillaries (g1^ of an

inch per second), and that the
capillary walls are very thin,
being made of only the inner
of the three coats that make
the veins and arteries. Here,
then, are two favorable con-
ditions for giving up the nu-
trition (Fig. 96). We learned
that the albumin, sugar, and
fats were dissolved in the
plasma, or liquid portion of
the blood. The plasma
passes through the thin cap-

Capillaries connecting a small artery, a, iHary walls, Carrying the
with a small vein, b. J J

food with it. When it gets

outside the capillaries, it is next to the walls of the
cells that make up the tissues. These spaces are called
lymph spaces. Thus the lymph bathes the cells in the
nutritious fluid, and the hungry cells absorb what they
need.

175. The red corpuscles bearing the oxygen cannot get
through the capillary walls. Oxygen is a gas, however,

FIG. 96.

THE CIRCULATION

105

and the walls of the capillaries are so thin that they offer
no hindrance to the passage of the oxygen into the cells in
the tissues. Carbon dioxid, which is one of the products
of the combination of oxygen with the food material in
the tissues, is also a gas, and it passes back through
the capillary walls into the blood, which takes it back
to the heart, and thence to the lungs to be sent out of
the body.

176. Why cannot the capillaries themselves carry the
food into the tissues ? Because they are tubes, and as long
as the food is in the blood it

cannot reach the cells ; the
capillary walls prevent. The
lymph spaces and the lym-
phatics act as middlemen be-
tween the blood and the cells
(Fig. 97).

177. Necessity for the Lym- FIG. 97.— Diagram to show Function

phatic System. — If the plasma
kept coming into the tissues
without any way of getting back into the blood vessels,
the blood would soon be lacking in plasma and the tissues
would be oppressed with it. We see, then, the absolute
necessity for some provision to get this liquid bark into
the blood vessels, from which it is constantly overflowing,
This is done by a system of tubes called the lymphatics
(Fig. 98).

178. What is lymph ? The blood plasma is called
lymph after it gets out of the capillaries. But it soon be-
comes changed by the addition of substances thrown out
by the cells, and by giving up to the cells the digested
food brought by the blood. We should have said also that
the white blood corpuscles may pass out into the lymph,
especially if there is some condition in the tissues that they
can correct (Fig. 82).

of Lymph.
A, tissue cells ; C, capillary; L, lymphatic.

io6

ELEMENTS OF PHYSIOLOGY

179. We may say, then, that lymph is nearly the same
as the blood without the red corpuscles. Did you ever
see any lymph ? Certainly you have seen it, many times.
Whenever there is a blister in the skin from friction, or
from a burn, the lymph collects. Sometimes when the
skin is grazed, but no blood vessel touched, the lymph
may exude.

180. The Origin and Course of the Lymphatics.— Unlike
the blood vessels, the lymphatics, or the tubes which carry

the lymph, have a beginning. The blood
vessels do not begin, but make a never-
ending circle. The lymphatics begin in
open ends between the capillaries and the
cells, or among the cells themselves (Fig. 97).
It will be interesting to learn how they
lead the lymph back to the circulation, and
what makes it flow, for surely there is no
heart for the lymph as there is for the
blood. When the lymph once enters the
open end of the lymphatic, it does not
return to the blood, but continues to move
slowly or at intervals through the lymphatics
on its return to the blood system (Fig. 98).
Small lymphatics come together and form
larger ones. They continue to unite and
form larger ones, until finally the lymphatics
from nearly the entire body unite into one
FIG. 98. — The iarpre tube, which passes up through the

larger Lympha- *

tics of the Front abdomen and thorax, and pours the lymph
of the Right Arm. into t^Q venous system beneath the. collar

g; lymphatic glands. . . „,, . .. . ..

bone near the neck. This largest of all
lymphatics is called the thoracic duct.

181. The Thoracic Duct is about the size of a goose quill,
and empties into the venous system just where the large
vein from the left side of the head (the left jugular vein)

THE CIRCULATION

107

joins the large vein from the left arm (left subclavian vein)

(Fig. 99). We said the lymphatics from nearly all over the

body form the thoracic duct;

but the lymphatics from the

right arm and right side of the

trunk and head form what is

called the right lymphatic duct,

which empties into the right

subclavian vein just where the

right jugular vein joins the

latter (see Plates).

182. What makes the
Lymph flow ? — Did we not
learn that something besides
the heart makes the blood
flow ? It is the contraction
of the muscles and their con-
sequent pressure upon the
veins. The valves in the
veins make this pressure
effective by allowing the
blood to be forced in only
one direction. It is likewise
found that the lymphatics
have valves, and that they are
more abundant than those of
the veins. Whenever the
muscles contract, the lymph
is forced along, and the valves
provide that no progress made
shall" be lost by any backward
movement. Every pressure
leaves a part of the lymphatic
empty and ready to fill from behind (Fig. 100). Also, if
the body is pressed upon or shaken, as when riding a trot-

FlG. 99. — The Thoracic Duct.

i, part of ribs ; a, receptaculum chyli ; b,
trunk of thoracic duct, opening at c into
junction of left jugular (/) and left sub-
clavian ( g") veins. The connection of these
veins with the superior vena cava(A) has
been cut across to show the thoracic duct
behind it ; d, lymphatic glands in the lum-
bar regions.

io8

ELEMENTS OF PHYSIOLOGY

ting horse, or in a jolting vehicle, the lymph is moved be-
yond the valves at every jolt, and its circulation aided.

183, The' secret of the powerful effect of muscular work
upon the health lies chiefly in the great aid that it gives
the lymphatic and venous circulations. The
importance of an active lymphatic circulation
is seen when we remember that the blood
does not make its exchange directly with the
cells of the tissues, but with the lymph, and
the lymph makes the exchanges with the
tissue cells.

184. The Lymphatic Glands. — Along the
course of the lymphatics, numerous enlarge-
ments occur called lymph nodes or lymph
glands (Fig. 101). They
consist of a connective
tissue framework, the
meshes of which are
crowded with lymph cells.
The lymph in its course
must filter through these
clusters of cells, and, in
doing so, is purified; for
the node cells take up
impurities in the lymph,
and work over and change
The cells in these nodes
multiply, and some of them are taken up
by the lymph and carried into the blood
to become those remarkable little bodies,
the white blood corpuscles. It is a curi-
ous fact that the older white corpuscles
are broken up in the lymph nodes, and their remains are
absorbed by the newly formed white corpuscles, just as the
latter absorb germs and other foreign particles that may

FIG. loo. — A Full
Lymphatic with
its Valves dis-
tended.

their nature.

FIG. 101. — Lymphatic
Gland.

Showing valved lymphatics
entering and leaving it.

THE CIRCULATION IOQ

enter the blood. The lymphatics penetrate and help in
the nourishment of every tissue, even in that of the bony
tissue (Fig. 102).

185. The Spleen. — This organ resembles the lymph nodes.
It is purplish red, about five inches in length, and is situ-
ated just inside of the lower

ribs on the left side of the
abdomen. White corpuscles
are formed in it as well as in
the smaller lymph nodes. In
it also the red corpuscles that
have finished their service
in the blood are probably
broken up and destroyed.

HYGIENE OF THE CIRCU- FIG. 102. — Section of a Haversian
T ATTrkxr Canal, showing its Contents, highly

magnified.

186. Have VOU learned Vet a> sma11 arterial capillary vessel; v, large

J venous capillary; «, pale nerve fibers cut

the CUrioUS fact that all 01 the across ; /, cleftlike lymphatic vessel; one

,.. ,, r ,•• « j i« °f the cells forming its wall communi-

llVing CellS 01 the DOdy live cates by fine branches with the branches

under water, j ust as the ameba of a bone corpuscle-
does ? The lymph and the blood are chiefly water and the
cells are all bathed continually in one or the other. The
blood bathes the cells in the walls of its vessels, and the
lymph, or the blood without the red corpuscles, is found
filling the interstices or spaces between the cells, like water
in a sponge. From the spaces, as we learned, it is taken
by the lymphatics in order to make room for fresh lymph,
free from waste material and bringing fresh nourishment.
The only exception to the rule that the cells live a
watery existence, is found on the surface of the body ; the
cells of the outer skin, hair, and nails, however, may be
called dying cells, for they are not alive in the same sense
that the other cells are : they do not contain nuclei and
cannot repair themselves or grow.

1 1 0 ELEMENTS OF PHYSIOL OGY

187. The supreme, the transcendent importance to the
health of the tissues, of pure blood and good circulation, now
becomes apparent. All that the cells need, in order to be
sound and vigorous, is to have good food and oxygen
brought within their reach, and to have the waste material,
or products of combustion, removed ; the circulation meets
these needs.

188. When unsoundness occurs in any part of the body,
there is a strong probability that the circulation there
is defective. The hair is lost by cutting off the circulation
from the scalp. The eyes may become inflamed, or the lids
diseased, because of obstructing in the neck the return
of the blood from the head; improper neck clothing or
stiffened muscles may cause this obstruction. A corn
grows on the toe because of the interruption of the circula-
tion there, resulting from intermittent pressure of the
upper leather of a tight shoe upon the toe as the foot
lengthens and shortens at every step. Indigestion may
result if vigorous mental or physical activity, just after
eating, draws the blood away and prevents the secretion
of the digestive fluids. Gout may occur from the deposit
of waste materials in the spaces around the joints where
the pressure from the circulation is least. Colds occur
when the blood vessels in the walls of the air passages be-
come congested or swollen with blood, and the vessels lose
their tone so that they cannot contract and keep the blood
moving onward.

189. Pure Blood is just as necessary as free and unim-
peded circulation. We shall learn later how the digestive
organs serve to furnish the nutrition, how the lungs furnish
the oxygen, and how the skin, kidneys, and lungs remove
from the blood the impurities and waste materials.

190. Taking Cold. — Sudden or prolonged exposure to
cold while the muscles are inactive, so stimulates the sur-
face blood vessels through the vasomotor nerves that they

THE CIRCULATION III

become tightly contracted and send the blood to the in-
terior of the body. It accumulates there and may cause
such congestion of the mucous membrane of the nose,
throat, windpipe, or lungs, that inflammation ensues. A
cold is an inflammation of the mucous membrane of part
of the air passages. Rapid cooling off from a heated
condition, especially if one is in a profuse perspiration,
may cause the same results ; or, exposure to moderate but
continuous cold without exercising may bring on a cold.
Sitting on the damp ground, sitting with damp feet, sitting
for a long time in a cool draught, or going thinly clad in cool
weather, may cause a cold; only foolish persons think
they are so hardened as to withstand such risks without
injury. Persons who pay attention to their feelings and
instincts can detect the beginning of any such derange-
ment of the circulation, and prevent trouble by timely
prudence.

191. A person may be in the habit of coddling himself
by living in overheated rooms, or by wearing too warm
clothing and by constant use of mufflers on going out ; his
surface nerves thus become so delicate ^nd the blood vessels
of the surface so relaxed, as to insure taking cold on every
accidental or unavoidable exposure. A better plan is to
keep the house cool, the thermometer standing at 65° or
70°, sleep with open windows, take cool baths, and keep
warm when out of doors by walking or exercising briskly.
Thus the blood vessels are toned up, the circulation is made
vigorous and steady, and the person is better fitted to with-
stand the ordinary conditions of life without disease con-
tinually recurring owing to deranged or weak circulation.
Any process of " hardening to cold " that is not accom-
panied by vigorous exercise, is a risk to the health.

192. The reciprocal action of the blood vessels of the skin
and the internal organs is sometimes illustrated when a
person drinks freely of cold water. There is a sudden

112 ELEMENTS OF PHYSIOLOGY

breaking out of perspiration. Why is this ? Certainly the
water does not reach the skin so quickly. The cold in
the interior stimulates the internal vessels to contraction
and the blood is diverted to the unstimulated vessels of the
skin, surrounding the sweat glands.

193. Effects of Unusual Exercise. — If a person has
sedentary habits and has neglected active exercise for
some time, the heart, as well as the other muscles, becomes
weak. If such a person hurries to catch a train, or takes
very rapid and trying exercise of any kind, he may bring
on an unpleasant palpitation of the heart, which is a warn-
ing to desist at once. Violent exercise should not be taken
until one has gradually led up to it.

194. Sleep and the Blood. — A person who loses much
sleep becomes pale ; the paleness is evidence of a diminu-
tion in the number of red corpuscles. It is during sleep
that the corpuscles that have been worn out during the day
are replaced, but loss of sleep causes a greater loss to the
blood than usual, with less than the usual opportunity for
repair.

195. Mental Influences. — Rage excites and strains the
heart. The unexpected receipt of joyful news sometimes
so acts upon the heart through the emotions as to cause
death. Thinking intently of an organ may cause an in-
crease of the circulation in it.

196. Clothing. — The blood cannot circulate with perfect
freedom unless the entire body is so loosely clothed that
there is no pressure upon any of the blood vessels, no
interference with the lungs as they expand, no pressure
upon the stomach, liver, and intestines. Many of the
largest veins, particularly those of the arms and legs, lie
so near the surface that any tightness of the clothing
is certain to diminish the flow of blood through them.
Sleeve supporters and garters, if used at all, should be
of weak elastic with adjustable buckle, and no tighter

THE CIRCULATION 113

than is absolutely necessary. It is especially necessary to
keep the extremities warmly clad and dry.

197. Effects of Alcohol upon the White Corpuscles. — Dr.
Woodhead, of the University of Cambridge, says that the
white corpuscles are injured by alcohol in the blood, and
that they lose to some extent their activity in attacking
poisons and germs of disease. This gives an explanation
of the susceptibility of drinking men to germ diseases.
Persons accustomed to use alcohol are usually the first vic-
tims of cholera and of yellow fever ; while some abstainers,
under constant exposure, remain untouched. The white
corpuscles repair cuts and broken bones ; hence intemperate
persons do not recover from accidents and surgical opera-
tions as quickly as do total abstainers.

198. Effect of Alcohol upon the Red Corpuscles. — The
red corpuscles carry the oxygen. When alcohol is freely
taken, the red corpuscles are injured so that the blood loses
in part its power to carry oxygen. The injury is to the
red coloring matter of the corpuscles.

199. How the Heart may beat faster without expending
More Strength. — Prof. Destree says that increased action
of the heart only appears to be a stimulation, and that
alcohol is a narcotic (from the Greek narkonn, to benumb).
Its effect on the heart is thus explained : The benumbing
effect of the alcohol upon the constrictor nerves (§ 160) of
the arterial walls, paralyzes these walls, allowing them and
the capillaries to dilate, thus lessening the friction and re-
ducing the blood pressure in the vessels. The heart keeps
on exerting the same force from habit ; and since it is pump-
ing against less resistance, the same exertions of the heart
suffice to make it pump faster for a time and send the blood
over the body faster. When a dam is broken down, the
water flows faster for a time ; the force of the flow, how-
ever, is not supplied by the weakness of the dam in break-
ing down.

i

1 1 4 ELEMENTS OF PH YSIOL OGY

200. But Alcohol affects the Heart itself. — " The valves,
which consist of folds of membrane, lose their suppleness
and become diseased and weakened. The muscular fiber
of the heart is replaced by fatty cells, so that the power of
contraction is greatly reduced. These derangements are
likely to cause death from sudden failure of the heart itself,
or from rupture of the weakened blood vessels, and oozing
of the blood in the brain, producing apoplexy " (G. H.
McMichael, M.D.). The condition of the heart mentioned
above is called fatty degeneration of the heart.

201. Hemorrhage is a flow of blood from an injured
blood vessel. When the wound is slight, the clotting of the
blood stops the flow. Clotting is rapid in the blood of
healthy persons and slow in the blood of poorly nour-
ished persons. Blood does not spurt from a cut vein but
flows in a slow stream. When an artery is cut, the blood
comes forth in a jet, with stronger spurts at each throb of
the heart. In a large artery the pressure is so strong that
it forces away the clot as fast as it is formed, so that death
may result from loss of blood.

202. Tobacco Heart, or Trotting Heart. — Tobacco, unlike
alcohol, does not dilate the blood vessels of the skin ; to-
bacco users are often pale from want of blood in the skin.
We thus see why tobacco users develop a stronger craving
for drink than non-users, because the alcohol has, in some
respects, an effect opposite to that of tobacco. However,
heart action is temporarily increased when tobacco is used.
In the present chapter you learned that the sympathetic
nerves increase the heart action and the vagus nerves hold
ft in check. The vagus is partially paralyzed by to-
bacco, and the heart beats with more force, thus ex-
hausting itself. The pulse of the habitual user shows
unmistakably the injury done to the heart. It loses the
firm steady beat of health and becomes irregular. Most
of the time its beat is feeble, but for a short period its

THE CIRCULATION 1 15

beat may be rapid and palpitating. This condition is
known to physicians as the " tobacco heart." The short
period of palpitation has caused it to be named in Eng-
land, the " trotting heart." Physicians who have made a
special study of the subject, claim that one out of every
four tobacco users has the tobacco heart. It prevents
success in athletic contests and feats of strength. It pre-
vented a large proportion of the young men who applied
for enlistment, during the recent war with Spain, from
entering the army. Knowing the paramount importance
to sound health of rich blood and perfect circulation,
we are ftot surprised to know that the whole body is
enfeebled by tobacco, and that mental as well as physical
vigor is impaired. Observant teachers can often tell
which of the boys in school are addicted to the use of
tobacco from the comparative inferiority of their ap-
pearance and from their indolence of body and mind.

203. THOUGHT LESSON. Comparison of Arteries and
Veins. — (If this is made a written exercise, underline the
words which you supply.)

Walls. — The walls of the are very elastic, while

the walls of the are slightly elastic. The walls of

the are thicker and stiffer than the walls of the .

It is necessary that they should be so, because they must
sustain the of the .

Work of each. — The arteries take pure blood from

the to the , and impure blood from the

to the . The veins take pure blood from the

to the , and impure blood from the to the .

Connections at heart. — The are connected with the

auricles. The are connected with the ventricles.

Rate of flow. — The blood flows more rapidly in
the .

Manner of flow. — The blood in the flows uniformly.

The blood in the flows .

1 1 6 ELEMENTS OF PH YSIOL OGY

Control of flow. — The are abundantly supplied with

— . The have none.

Location. — The arteries as a general rule are located
-. The veins are generally located . This adds

to the of the body.

Definitions. — The arteries are tubes that carry blood
(both pure and impure) to the .

The veins are tubes that carry blood (both pure and
impure) from the .

Accidents. — If an artery is cut, the pressure is to be

applied - — the cut and the . If a vein is cut, the

pressure is to be applied - — the cut. A cut vein may be
told from a cut artery in the three following ways : —

204. Activity is the most necessary condition for the health
of a cell. In every cell is found matter in three conditions :
that which is actually living, that which was recently living,
and that which is about to live by being transformed in the cell.
The transformation from lifeless to living, and from living to
dead, and the removal of dead matter must go on promptly.
Anything which interferes with this activity interferes with
the health of the cells. When life is natural and complete,
all the organs are given work to do and are healthy, active,
and strong; there is a feeling of buoyant happiness, the
mind is clear, the will is firm, and the man truly lives.

APPLIED PHYSIOLOGY
EXERCISE I

1. The main arteries run down the middle of each limb close to the
bone on the side toward which the limb bends. Why do they have
this position?

2. Where is the thickest wall of the heart? (See Fig. 85.) Why?
The thinnest walls? Why?

3. Why do we need warmer covering when asleep than awake?

4. When would it be pleasant to throw off a coat or cloak, but
imprudent to do so?

THE CIRCULATION' 1 1/

5. If the clothing has been accidentally wet and the wet garments
cannot be changed for dry ones at once, how can one keep up a good
circulation to prevent taking cold ?

6. Why does the toper have a red nose?

7. When cold air strikes it, why does the face first blanch and then
flush (§§ 156, 1 60)?

8. When a person is warm-hearted in the usual sense of the term,
is it also true physiologically ?

9. What is the origin of the term "blue-blooded aristocracy"?
When do dark veins in the wrist show most plainly? Of what is
dark blood in the body in general a sign ?

10. Why does a hot foot-bath sometimes relieve a headache? Why
should it relieve a cold in the head?

EXERCISE H

1 1 . Tight clothing at the waist may cause too much blood in what
parts? Does it tend to make the circulation sluggish or active?

12. Which is more compressible, a vein or an artery ? Does a tight
garter interfere more with the flow of blood to the feet or from the feet?

13. Why are varicose veins so often found in the lower leg?

14. Why may a sluggish circulation through full veins in the feet
as well as want of blood in the feet cause them to be cold ?

15. Why are students very likely to have cold feet?

1 6. Why does the body of a person dying by drowning or strangula-
tion turn blue?

17. What would you do in the case of a severe wound in the absence
of a surgeon ?

1 8. What is the object of a collar? Why is it therefore not neces-
sary to have the collar as high in front as behind ? Why is it unhealth-
ful to have it so? What is the purpose of a cuff?

19. What is the most serious injury of alcohol to the blood?

20. In what part of the circulation does the so-called venous blood
flow through arteries ?

EXERCISE HI

21. Show how life comes by death (§ 204).

22. Can any physiological basis be given for the claims of patent
medicine venders that their nostrums "purify the blood"?

23. What vein begins and ends with capillaries (Fig. 89) ?

24. What artery takes arterial blood to an organ where it is still
further purified, yet is called venous blood when it leaves the organ ?

ii8 ELEMENTS OF PHYSIOLOGY

(As it leaves that organ the blood is the purest in the body.) (See
Plate V.)

25. How does alcohol interfere with the process of oxidation?

26. What keeps the blood in circulation between the beats of the
heart?

27. What are the functions of the capillaries?

28. Why does a cool draft in the house cause a cold quicker than a
cool wind out of doors?

29. Why do we perspire freely after drinking freely of cold water?

30. How can an extensive burn cause death by congestion of the
lungs ?

31. What causes the difference between the hard hand of the black-
smith and the soft hand of the clerk?

32. Why does rubbing wear out the leather of the shoe, but the
friction of the shoe upon the toe cause the skin to grow thicker and
to form a corn (§ 188)?

33. What is the effect upon the circulation of traveling upon the
cars or in a vehicle?

CHAPTER IX

THE MUSCLES

205. It has been learned that motion is one of the
physiological properties of protoplasm, along with sensi-
bility and the power of assimilating

food. The white blood cells have

a distinct motion, and certain cells

that line the windpipe and other

air passages are able to contract

and wave their cilia, or hairlike

appendages, to and fro. With these

two exceptions, the muscle cells are

the only cells of the body that have

a marked power of contracting and

producing motion. As feeling or

perceiving through the nerves, and

moving or exerting energy through

the muscles, seem to be the two

chief purposes of the organism, we see how important the

muscles are for the purposes of life. The body has been

compared to a steam engine but the only object of an

engine is to set free energy.

206. Kinds of Muscles. — Muscular tissue occurs in
nearly every organ. We found that it helps to form the
walls of the blood vessels, and assists in the circulation
of the blood ; the eyeballs are moved by six sets of
muscles; the act of swallowing is performed by muscular
contraction in the gullet; the contraction of the muscles
in the walls of the stomach produces the motion by which

119

FIG. 103. — A Portion of
Two Striated Muscle Fi-
bers, highly magnified.

«, nucleus.

I2O

ELEMENTS OF PHYSIOLOGY

the food is mixed ; in the intestines the muscles keep the
partly digested food in motion ; the muscles in the limbs
enable us to move and work ; the
heart is chiefly muscle ; the muscles
in the chest and trunk enable us to
breathe ; those in the larynx are used
in talking. Muscles have been divided
into two classes, voluntary and invol-
untary. The first class is under the
control of the will, either at all times
or part of the time : the second is
never under the control of the will ;
their work goes on quite independ-
ently of the will and even during
sleep. Can you assign to their proper
classes the muscles that have been
named in this paragraph ?

207. Structure of Muscles. — In
studying the master tissues we
studied muscular tissue in general,
and learned how a muscle is able
to shorten. The contraction of a
muscle is caused by the contraction

showing the capillary vessels °f the individual fiber-cells which
compose it. Each fiber shortens in

length and becomes proportionally thicker ; the sum total
of the contractions of these fiber-cells taking place at the
same time, makes up the contraction of the whole muscle.
The number of fibers lying side by side determines the
thickness of the muscle, and the amount of strength with
which it can contract ; while the number of fibers lying end
to end determines the amount of shortening or contraction
of which the muscle is capable. When a muscle is habitu-
ally used, it becomes larger, firmer, darker, and stronger.
208. Voluntary and involuntary muscles are not con-

,

FIG. 104. — A Portion of

Three striated Muscle

THE MUSCLES

121

FIG. 105. — Fibers of Non-striated Mus-
cles, or Involuntary Muscles.

structed exactly alike. Examined under the microscope,
each fiber of a voluntary muscle shows bright bands

alternating with dark bands,
running across it (Fig. 103).
These bands give the whole
muscle a striated or striped
appearance under the mi-
croscope, hence this kind
of muscle is called striated
muscle (Fig. 104). The fi-
bers are bound together by
connective tissue into bundles called fascicles and these
again into larger bundles. The connective tissue surround-
ing the bundles can be plainly seen in
chipped beef, also in fresh beef and
boiled beef. The voluntary muscles are
darker red than the involuntary. Lean
meat is made up of these muscles. They
are near the surface, but their outlines
under the skin are obscured to a greater
or less degree in different persons, ac-
cording to the thickness of the layer of
fat between the muscles and the skin.
These muscles are usually attached to
bones. They contract quickly, while
the involuntary muscles contract slowly.
209. Involuntary Muscles are found
in the walls of the alimentary canal, the
bladder, the gullet and several other
organs ; all such muscles are composed
of fibers which are not striated, and are, therefore, called
plain muscle fibers. A striated fiber is about one inch in
length and yj^ of an inch in thickness and is shaped some-
what like a cylinder ; it possesses several nuclei. A plain
muscle fiber is not more than ^^U- of an inch in length,

FIG. 106. — Two Cardiac
Muscle Fibers.

«, nucleus; /, line of junc-
tion between the two cells ;
/, process joining a simi-
lar process of another cell.
(Magnified 400 diameters.)

122 ELEMENTS OF PHYSIOLOGY

has the form of a very slender spindle, and contains one
nucleus (Figs. 27, 105). The fibers interlace and are held
together by fine connective tissue to make the hollow,
slow, involuntary muscles.

210. Cardiac Muscular Tissue, of which the heart con-
sists, differs from both striated and plain muscular tissue
(Fig. 106). Its fibers possess one nucleus, like plain
fibers ; they are not spindle-shaped and narrow, however,
but broader and cylindrical. They are, moreover, faintly
cross-striated by light and dark bands. We may say, there-
fore, that although the heart is in every respect an involun-
tary muscle, it has more resemblance to striated than to
plain muscle. The many muscles used in breathing are at
times voluntary, and at other times involuntary ; but they
are all striated muscles with the usual structure.

211. THOUGHT LESSON. Effects of Unhygienic Shoes. —

1. What the faults of shoes
may be (in shape, size, sole, heel,
toe, and instep).

2. Deformities resulting to
foot (skin of foot, nails, joints,
arch, instep, and ankle).

3. Effects of improper shoes
on habits of life.

FIG. 107. - A Natural Foot. 4- Effect on particular organs

or functions.

5. Gain and loss to personal appearance from wearing
improper shoes.

6. Effect on mind and disposition.

7. If a shoe is too loose, it slips up and down at the heel
and chafes the skin there. If too tight, there is pressure
on the toes, which causes a corn or ingrowing nail. Have
your shoes been correct or have they been too loose or too
tight ? What proportion of people wear shoes that are too
tight ?

THE MUSCLES

123

FIG. 108. — A Deformed
Foot in an Unhygienic
Shoe.

FIG. 109. — The Natural
Shape of the Sole.

FIG. no. — Showing the
Toes unduly crowded,
with Corns, caused by
Tight Shoes.

FIG. in.— The Track
made by a Natural
Foot. Make a test
by wetting your bare
foot and noticing
the track made upon
the floor.

FIG. ii2. — The Traik
made by a Foot in
which the Natural
Arch has been partly
broken down by
Tight Shoes.

If the arch breaks down
entirely the foot is called
" flat foot."

FIG. 113. — Sole of
Foot.

Showing some of the
muscles and tendons
that bend the toes.

124 ELEMENTS OF PHYSIOLOGY

8. How many sprained ankles have you known of?
Were the sufferers mostly boys or girls ? Why ?

Most people assume the following rule in selecting a
shoe : If you can just draw on a shoe without much effort

and sit with it on the foot for
ten minutes, it will be comfort-
able to walk in and wear all day.
Yet such a shoe is one size too
FIG. n4.-skeieton of F^ol if small for walking. Many mak-

the child never goes barefooted, ers no longer number their shoes

the arch is likely to become .

flattened instead of high. plainly because of the vanity of

some purchasers. A new shoe
should be as comfortable as an old one.

9. What is the general arrangement of the bones of the
foot ? Does the weight of the body come upon the middle
of the arch ? How can this arch be injured and what is
such a deformity called ?

10. Why is it that people who grow up in warm climates
are more likely to have high arched insteps and elastic
feet than those who pass their childhood in cold cli-
mates ?

Persons who, because of silly jokes about big feet or for
other reasons, have the idea that the shoe should leave no
extra room, but should fit as if it were covering a wooden
foot, will always get uncomfortable shoes.

212. THOUGHT LESSON. Compare the voluntary and
involuntary muscles by writing in two columns headed,
Voluntary Muscles and Involuntary Muscles, the facts con-
cerning their Control, Structure, Color, Position in Body,
Attachment, Rate of Contraction, Number of Nuclei,
Length of Fibers, Breadth of Fibers, Shape of Fibers.
(Place these titles in a third column.)

213. The Attachment of Muscles. — The involuntary
muscles are usually tubular or hollow, and surround the
internal organs. They are sometimes called the visceral

THE MUSCLES

125

muscles because the internal organs are called the viscera.
The quicker, stronger-acting voluntary mus-
cles are sometimes called the skeletal muscles
because nearly all of them are attached to
bones. Exceptions to this are the sphincter
muscles or circular muscles that surround
orifices, as the muscles that pucker the
mouth and squint the eye. There are about
five hundred voluntary muscles. By study-
ing the figures you will notice that the mid-
dle portion of these muscles is usually large
and full, and that the muscles taper to small
cords at the ends (Fig. 113, etc.). The

FIG. 115.— Striated v

Muscular Fibers muscles of the calf move the foot, and the
(a) terminating muscies of the forearm move the hand. If

in lendon (o).

the full round muscles extended down over
the wrists and ankles, it would make these as large around
as the forearm or calf,
and the wrists and
ankles would be very
clumsy and awkward.
It is found that the con-
nective tissue which
binds the fibers of a mus-
cle into bundles and forms
sheaths for the bundles,
extends beyond the mus-
cular tissue and unites to
form a dense, inelastic,

White

a tendon
. \ .-i-,, rv

115). The fibers are
very closely packed together and make a very strong cord.
One no thicker than a lead pencil is strong enough to
support twice the weight of the body. A tendon contains

FlG. 116. — Diagram to show the Action of the
Biceps Muscle of the Arm.

COrd The two tendons by which the muscle is attached to
the scapula are seen at a ; P, the point of attach-
(Fig. ment of the muscle to the radius; Ft the elbow
joint; W, the weight of the hand.

126

ELEMENTS OF PHYSIOLOGY

no nerves and very few blood vessels. Some muscles
have a tendon at only one end ; some have no tendon but
are attached directly to bones. Find muscles without
tendons by studying the figures. The cordlike nature of
tendons can be ascertained by feeling the tendons under
the knees, called hamstrings, or the tendons in the angle
of the elbow.

4

FIG. 117. — Tapping
Floor with Toe.
Lever of first order.

FIG. 118. — Raising
Weight of Body
upon Ankle.

Lever of second order.

FIG. 119.— Raising
a Weight upon
Toes.

Lever of third order.

214. How Muscles and Bones Cooperate. — When you
grasp a heavy weight in the hand and lift it by bending the
elbow, where is the muscle that does the work ? You will
easily find it in the upper arm ; this muscle is called the
biceps because it is attached to the shoulder blade above by
two tendons. The lower arm acts as a lever with the
fulcrum, or fixed point of the lever, at the elbow (Fig. 1 16).
It is easy to see that a slight contraction of the biceps
muscle will move the weight a greater distance than is
accounted for by the shortening caused by the actual con-
traction of the muscle. This is what the bones usually
accomplish for the muscles; they change a slow, short,
inadequate movement into a long, swift movement. While
the muscle contracts an inch, the bone may move a foot.
The bones thus add greatly to the range and rate of motion.

215, Figures 117, 118, and 119 show the three orders of
levers. In the lever of the first order, the fulcrum (F) is

THE MUSCLES

127

7

between the power (P) and the weight ( W). In the lever

of the second order the weight is between the other two, and

in the lever of the third order the power

is between the others. In Fig. 116 the

biceps muscle acts on the radius and ulna

fastened together as one, turning at the

elbow as a fulcrum ; the weight to be

lifted is in the hand. This is evidently a

lever of the third order with the power

between the other points. In this case it

takes a force in the muscle equal to about

six pounds to raise one pound in the hand.

216. Figure 120 shows how the muscles
may act as levers upon the bones to pre-
vent the bones from turning upon the joints
as fulcrums; thus the body is held erect.
Where are the muscles located that keep
the body from falling or bending forward
(Fig. 120)? From falling backward?
(Which of the two sets is in front ?) What
kind of lever is illustrated by the head tilted
upon the atlas (Fig. 121)?

217. Names and Positions of Muscles. —
A few of the important muscles are here
mentioned: The scalp muscle (Fig. 122)

passes over the top of the head ; it raises FlG- I20.— Diagram
the skin over the eyes, and (in some
persons) moves the scalp. The two pairs
of chewing muscles are the temporal and
masseter (Fig. 122). You can feel the temporal muscle
swell and harden if you place your finger on the temple and
close your mouth forcibly. In the same manner you may
feel the contraction of the masseter by placing the fingers
just below the cheek bone. The muscle used in bowing
passes obliquely down on the side of the neck to the

of the Muscles that
keep the Body
erect.

128

ELEMENTS OF PHYSIOLOGY

collar bone (Fig. 124). It can be felt as a thick band;

when the head is turned to one side, it stands out as a

ridge. When one of the two acts alone,

it tu:ns the face so as to look to the other

side. When both act they bow the head.

The deltoid (Figs. 123, 124), or shoulder

cap muscle, raises the whole arm outward

and upward from the side. Can you locate

it by the feeling of fatigue after raising

the arm twenty times ? The biceps can tilt'ed upo'n Atlaes*

be seen and felt contracting on the front

of the arm when bent at the elbow. The triceps is on

the opposite side of the arm and straightens the elbow

TRAPEZIUS
DELT0/&

FIG. 122. — Muscles of Head and
Neck. Find the following mus-
cles : —

Chewing muscles; scalp muscles; bow-
ing muscle of one side; muscle that
holds head erect (upper part of
trapezius at back of neck) ; muscle
that squints the eye ; muscle that
pouts the lips; muscle that broadens
the mouth in smiling; muscle that
raises corners of mouth ; muscle that
draws down corner of mouth.

FIG. 123.— Principal Muscles of the
Back.

Trapezius draws shoulder and head back ;
deltoid raises whole arm ; latissimus,
climbing muscle, ©bliquus internus and
obliquus externus draw abdominal wall
in and force abdominal contents against
the diaphragm, thus expelling air from
lungs.

THE MUSCLES

I29

(Figs. 124, 125). Which is used in striking a blow, the
biceps or the triceps ?

218. The sartorius ("tailor") muscle (Fig. 126) is nearly
two feet long and is the longest muscle in the body ; it passes
from the outer side of

the hip bone to the inner
side of the leg below the
knee, and is used in
crossing the leg; because
of the position assumed
by a tailor at work it is
named the tailor's mus-
cle. The gastrocnemius
is a thick muscle in the
calf of the leg, and raises
the heel (Fig. 125).
When is it used ? It is
attached to the heel by
the largest tendon in the
body, called the "tendon

Of Achilles." Ask the Fia 124- - Superficial View of Muscles of

Upper Part of Trunk, from the front,
teacher why it IS SO (Allen Thomson.)

called ; or read the story
of Achilles.

219. The trapezius
("four-sided") (Figs.
123, 125) is a large

muscle covering the back between the shoulders. It
draws the shoulders back and holds up the head. Can
you find the climbing muscle (Figs. 123, 124), or the
muscle that draws the arm backward and downward (latis-
simus or "broadest")? When a person hangs by the
hands, it helps to raise the body. It is a large spread-
out muscle extending from the humerus to the vertebral
column.

sterno-mastoid of the left side; 5, trapezius ; 6,
deltoid ; 7, upper part of triceps in the left arm ;
10, latissimus dorsi ; n, pectoralis major ; n', on
the right side, its clavicular portion ; 12, part of
pectoralis minor ; 13, serratus magnus ; 14, ex-
ternal oblique muscle of the abdomen ; 15, placed
on the tip of the sternum.

130

ELEMENTS OF PHYSIOLOGY

220. Each muscle has another muscle or other muscles
that can undo the work done by it. Two muscles with oppo-
site action or function are said to be antagonists. There is a
great fan-shaped muscle called \hzpectoralis (n, Fig. 124)

Cittnion of tht Hind

FlG. 125. — Full Figure Muscles (rear).

on the chest, extending from the sternum to the arm. It
draws the arm downward and inward. This muscle is very
large in birds and is used in flying. To what muscle is it
an antagonist ? Muscles that bend joints are called flexors.
Those that straighten joints are called extensors. To which
kind does the biceps belong ? Which extensor muscle is its
antagonist?

THE MUSCLES

221. Muscles are named from : their shape, as deltoid
(like the Greek letter delta, A ; their location, as tibialis (near
the tibia) ; their action, as flexors ; their manner of attach-
ment, as triceps (three-headed).

.Extensors of tht Hand
- - . - £le*on of the Hind

E«te«sor, of th. Tew

FIG. 126. — Full-figure Muscles (front).

222. THOUGHT LESSON. Anatomy and Physiology of
Muscles. — By studying the figures, apply these four pairs of
adjectives in their proper places in the lines below : long and
round ; thin and flat ; short and narrow ; broad and flat : —

i. The muscles of the face are and .

The muscles of the cranium are and .

132 ELEMENTS OF PHYSIOLOGY

The muscles of the trunk are and .

The muscles of the limbs are and .

2. Grasp your arm above the elbow and bend it. What
changes do you feel ?

3. Span the biceps, holding tip of finger in elbow and
thumb farther up the arm. About how many inches of its
length does the biceps lose by contracting?

4. What muscles are attached to the bones without ten-
dons ? (Examine figures in book; also think of meat you
have eaten.)

5. Why -is round steak usually the toughest steak ? the
most nutritious ?

6. Why is a fowl's leg dark meat although its breast is
white ? Why is a fowl's breast white and a dove's breast
dark (§§ 207, 220)?

7. Why does practicing looking cross-eyed have a tend-
ency to make one so ? (Give effect on both nerve and
muscle.)

8. Where are the muscles that bend the fingers ?

9. Name the places in the body where the tendons can
be most easily felt while the muscles are working.

223. How the Nerves and Muscles cooperate. — How
many ways of exciting the contractility of a muscle have
you learned ? When the food enters the stomach, the
mechanical stimulus starts impulses along the nerve to
the ganglion, and reflex impulses cause the involuntary
muscles in the walls of the stomach to contract. When
we desire to make a certain movement, an impulse is
sent from the brain along a nerve to the muscle which
performs this movement. This impulse sets the muscle
engine going somewhat as an electric current sent by
pressing .a button starts a bell to ringing or a machine to
running.

224. The muscular tissue is composed chiefly of albu-
minous material. It has been found that increased muscular

THE MUSCLES 133

action, such as mountain climbing, hardly increases the
amount of albuminous material (urea) excreted as waste.
Such activity, however, does largely increase the amount
of carbon dioxid given off. It is believed, therefore, that
our energy is largely derived from starches and sugars
(carbohydrates) and fats. The fact that beasts of burden
depend chiefly upon carbohydrate foods strengthens this
view. That muscles use sugar in their action is indicated
by the fact that the arteries take more sugar to the muscles
than is carried away from them by the veins.

225. The nerve impulse reaching the muscle causes it to
contract. This takes about ^V °f a second. It would relax
in gV °f a second also, and it can be kept in a state of con-
traction only by successive impulses, usually about 10 per
second. Thus it remains in a tremulous state of contraction.
The vibrations may become apparent during excitement,
or when a great effort is being made. If a muscle con-
tracts continuously for a long time, a time comes when
it can no longer be made to contract, not even by an
electric stimulus, but it becomes soft and relaxed. What
is the cause of this ? Are the oxygen and sugar and fat all
combined and changed into carbon dioxid ? Or, as we
say, is the strength all used up ? No, it is found that if
the carbon dioxid is allowed to escape but no fresh blood
allowed to come, the muscle can be made to contract again.
This shows that the accumulation of the carbon dioxid
gas and perhaps some acids besides, prevent the nerve
stimulus from having effect. The paralysis and aching of
extreme fatigue are thus caused. It is a very beneficent
thing that a healthy person undisturbed by poisonous drugs
or stimulants can never use up all his strength. A man
may have been ill for weeks, yet when delirious, and stimu-
lated by the poisons formed in the course of the disease, he
proves that he still has strength enough to overpower
several strong men.

134 ELEMENTS OF PHYSIOLOGY

226. Coordination of Several Muscles. — Would you like
to see two persons try to thread a needle, one holding the
thread and the other the needle ? Would they succeed
well ? Or in so simple a matter as the use of the knife and
fork in eating, could it be easily done if one holds the piece
of meat with the fork while the other tries to cut it ? Why
is it that the right hands of two persons cannot work so
well together as the right and left hands of one person ?
It is because of the nervous connection between the hands
of the same person, so that one hand knows just what the
other is doing. Let us think of what takes place in our
bodies when we throw a stone at a mark. At the same time
we see the mark, hold the stone in the hand and throw it.
In throwing a stone, at least a dozen muscles are used.
Each one of these must contract at the right time and
in the right way, or the stone will miss the mark. Each
muscle shortens under the influence of a nerve impulse
brought from the brain by a motor nerve. If one muscle
shortens an instant too soon, or a little too much, the stone
goes to one side. This working together of the muscles by
the aid of the nerves is called coordination. Coordination
is necessary, even in standing erect.

227. Nerve Expenditure. — It is found that the use of
many small muscles is much more exhausting than the use
of a few larger ones. This is on account of the nerve
energy consumed. A drummer beating a big bass drum
may do more muscular work than one who plays a tune
softly on the piano, but the piano playing exhausts the
performer much sooner. This is because the movements
of the wrist and fingers employ thirty muscles and a great
number of nerves. The striking of the keys with the ends
of the fingers where some of the most sensitive nerves of
the body terminate, may have some effect also, and may
help to explain why so many persons, especially young
ladies, who take little other exercise, have become nervous

THE MUSCLES 135

wrecks from piano playing. The typewriter has one of
the objections named above, but it has the advantage over
the pen of giving some variety of motion compared to the
monotonous use of the same muscles in penmanship.

228. Habitual Over-expenditure of Nervous and Muscular
Energy. — The fact that the muscles are arranged in pairs
as antagonists of each other may have a calamitous effect
in the case of persons with ill-regulated nervous systems.
Such persons, on account of anxiety or worry, doubt, or
overactive desire, keep their muscles drawn tense, the an-
tagonists pulling against each other, and after awhile they
lose the power of relaxing their muscles. They wear anx-
ious expressions, because the muscles of the face are never
relaxed or in repose. Their movements are nervous and
jerky instead of graceful and easy. Their breathing is not
deep and natural, because the breathing muscles pull
against each other, and their voices, therefore, are not even
and steady. They cannot be perfectly still, but chew gum
or a pencil, rock the chair, pull the mustache, etc. Do you
know of any of your friends who are handicapped by this
condition of over-tension ? When such people listen to a
sermon their backs get tired because they cannot relax com-
fortably to the seat and use their ears only while listening.
When they lie down, they try to hold the body on the bed,
and they keep the muscles of the neck tense as if trying
to hold the head on the shoulders. Such persons should
lie down for ten minutes twice a day and have an assistant
make a test to ascertain whether they are thoroughly re-
laxed ; let the assistant lift one arm and see whether it will
drop as if lifeless when released, or fall like a rope when
flung to one side ; let him find out also whether the head
is relaxed on the shoulders.

229. Over- tension is common to adults in cold cli-
mates, but is also known in warm climates. A graceful
person, like a child, uses just the muscles necessary for

136 ELEMENTS OF PHYSIOLOGY

any act, and no more. Ease of manner, as well as health,
make important the correction of conditions to which all
hurrying, ambitious persons are liable in an age of keen
competition and of ambition for learning and distinction.
Above all, repose of spirit and contentment of mind bring
grace and ease of body.

230. Muscular Tone. — That the muscles may be always
ready for use, they must not be entirely soft and flabby,
but under a condition of very slight contraction called tone.
We find that the muscular walls of the blood vessels possess
tone. It is this condition of slight contraction which causes
a wound in the flesh to gape open. If a tendon is cut, the
muscle shortens on account of its tone. If the nerve
going to the muscle is cut, the muscle lengthens a little,
that is, it relaxes, showing that there must be faint but con-
stant impulses coming through the nerve to keep the
muscle in tone. When one is asleep the body does not
lie perfectly straight, but the joints are slightly bent to
allow relaxation.

231. THOUGHT LESSON. Physiology of the Circula-
tion.— i. What do you notice after muscular exercise that
leads you to think that it makes the blood flow faster?

2. What must be the effect in a vein when a contracting
muscle presses upon it ? Why does this aid the blood-flow
in only one direction ?

3. What shows that exercise lessens the work of the heart ?

4. Why is standing still more tiresome than walking ?

5. Why is there need for valves in the veins (§ 167)?

6. Why is the activity of the kidneys greater in winter
than in summer, while with the skin the reverse is true

(§417)?

232. Physiological Effects of Muscular Activity. — It has
been explained how, during exercise, each muscle becomes,
as it were, a throbbing heart, squeezing the blood tubes
empty while contracting, and then relaxing and allowing

THE MUSCLES 137

them to fill up anew. This pumping is done by the pres-
sure of the thickened muscle fibers on the veins, the flow
being controlled by the valves. It has been actually ob-
served that the quantity of blood flowing through one of a
horse's muscles used in eating, was three times as great
when the animal was engaged in chewing oats as when the
muscle was at rest. This powerful effect upon the circula-
tion causes renewed nutriment to reach every neighboring
organ and tissue, and the waste material to be removed.
Through the effects of exercise upon the circulation, the
body is thus purified and made sound and strong (Fig. 128).

233. An Aid to the Memory. — In tracing the effect of
muscular work upon the different organs, let us take them
in the order in which the organs are located in the body.
Let us go in order from the outer organs to the deeper ones,
viz : skin, fat, muscles, skeleton, viscera. The viscera will
then be taken in order, beginning with the highest, viz :
brain, lungs, heart, digestive organs, and lastly, general
effects. By using this fixed order, all can be called to mind
without omission. It is recommended to the pupil that he
group other series of topics in his memory in the same way, ,
thus keeping the mental eye upon the body instead of upon
the pages of the book.

234. The Nine Effects of Muscular Exercise enumerated
in order are as follows : —

1. The Skin. — It opens the pores of the skin with
perspiration, fills the capillaries with fresh blood, and
improves the complexion by making the skin fresh, pink,
and smooth.

2. The Fat. — In cases of undue accumulation of fat, the
fat is burned up, and in cases of too great leanness, muscu-
lar exercise, by means of improved digestion and circulation
causes the fat to increase to the proper amount.

3. The Muscles. — Muscles affect themselves through
the improved circulation, and even the weakest and

138 ELEMENTS OF PHYSIOLOGY

thinnest muscles will grow large and strong, and the
flabbiest muscles will acquire a healthy tone, through
regular use. The condition of an arm carried in a sling is
an illustration of the effects of disuse.

4. The Skeleton. — The bones are better nourished, but
the chief benefit of exercise to them comes through the
improved strength and tone of the muscles by which
the bones are held in proper position. Thus deformed
cartilages and stretched ligaments, with the accompanying
round shoulders, flat chest, and spinal curvature are pre-
vented. A person with good muscles sits, stands, and
carries himself erect. One with weak muscles is apt to
slouch down.

5. The Brain. — The aid given to the heart by the con-
traction of the muscles makes the blood bound forward in
the vessels, and the pure fresh blood enables the brain to
work with greater ease and pleasure. This fresh blood is
still purer because of the increased expansion of the lungs.

6. The Lungs. — Gentle and slow exercise has little ef-
fect upon the lungs, but rapid and vigorous exercise expands
them till every nook and cell is filled, and the chest is de-
veloped and enlarged. A good-sized chest is very neces-
sary to good health.

7. The Heart. — The heart is aided in its work, as already
pointed out Long-continued exercise puts more demands
upon the heart, which becomes strong with the rest of the
muscles. With people who take no exercise, the heart
cannot be said to become flabby, but it may become weak,
just as any other muscle.

8. The Digestive Organs. — Exercise gives a good
appetite and prevents trouble in the stomach and clogging
of the intestines from which lazy people are apt to suffer.

9. General Effects. — It promotes good humor, prevents
vice and dissipation, gives one the agreeable look of health
and vigor. It is not the pitcher in the baseball team, or

THE MUSCLES 139

the industrious son, that is most often found loafing in a
back alley smoking cigarettes ; and it is not the industri-
ous, helpful daughter who is most often found with the
" blues," or nursing a headache.

235. Heredity. — The disastrous effect upon the heart
of a life of habitual muscular inactivity is apparent in the
lives of many people. The disappearance of dyspepsia
and many other diseases, with the remarkable restoration
to health that follows judicious muscular exercise or
physical labor, is likewise often seen. We have received
our bodies as an inheritance from an ancestry which dates
back at least to a time when the human race lived an
active life in the open air. The human body is adapted
to such conditions, and an attempt to change these con-
ditions too rapidly, as in the case of city dwellers, causes
extinction. The health and continuance of the race under
conditions of city life are aided by the continual influx of
healthy individuals from the country. In a human body
weighing one hundred and fifty pounds, there are about
sixty pounds of muscle, and we cannot neglect sixty pounds
of tissue with impunity and allow it to become unsound
from disuse (Fig. 126).

236. THOUGHT LESSON. Position of the Voluntary Mus-
cles.— On Figs. 125 and 126 mark the location of the
muscles having the functions named in the following
list. Locate them first in your body by performing the
action and feeling the muscle with your hand ; then mark
lightly with pencil. For instance, take question 4 : locate
the muscle that bends the elbow. This is found to be in
the front of the upper arm, and the figure " 4 " placed
on the dotted line drawn from that muscle.

Locate the muscle (or muscles) that —

1. Lifts the whole arm outward and upward.

2. Draws it downward and forward.

3. Draws it downward and backward.

I4O ELEMENTS OF PHYSIOLOGY

4. Bends the elbow. 10. Bends the knee.

5. Straightens the elbow* n. Straightens the knee.

6. Bends the fingers. 12. Raises the toes.

7. Straightens the fingers. 13. Raises the body on

8. Turns the head (Fig. 124). the toes.

9. Draws the shoulders back. 14. Crosses the legs.

237. Effect of Stimulants and Narcotics. —You learned
that true fatty tissue is formed by the accumulation of
oily material within the connective tissue cells (Fig. 38).

238. The weaker forms of alcohol, such as ale and beer,
cause a change into fat of much of the albumin in muscle
cells, thus bringing about a bloated and flabby condition,
called fatty degeneration. It may even reach the heart,
causing a dangerous disease called Jatty degeneration of the
heart. (There are other causes of fatty degeneration. If
an athlete who has developed enormous muscles, suddenly
ceases to train, his muscles may undergo fatty degen-
eration.) Through the narcotic or deadening effect of
alcohol upon the nerves, they become less sensitive, and
fatigue is not so readily perceived, so the drinker has a
deceptive feeling of strength and power. It was found
that two hours after taking two ounces of whisky mixed
with eight ounces of water, the muscular strength of
the man experimented on was reduced one third. This
means that a lifting power of three hundred pounds was
reduced to two hundred pounds. An old drunkard usu-
ally has a dragging gait and trembling hands. Coffee
sometimes causes a twitching of the eyelids ; this is a
sign that the body is being poisoned.

239. Forms of Exercise. — It is best to choose a form
of exercise or labor which you thoroughly enjoy. Most
games are excellent kinds of exercise. Baseball and foot-
ball, played in a sensible way, are admirable. Such games
not only strengthen the muscles but also develop presence
of mind, coolness, fearlessness, self-control, and other manly

THE MUSCLES 141

qualities. Men trained in such sports may often stop
panics and save lives in cases of accidents, or in other emer-
gencies. Walking, if not done too leisurely, is fine exer-
cise. Americans probably make too much use of street
cars. English women are noted as walkers, going many
miles at a time, and in the cooler parts of the United
States, and in cold weather in the Gulf states, this custom
would be equally beneficial in preventing nervousness and
weakness. Running is a still better exercise, but it should
be begun gradually and with caution, so as to give heart
and lungs opportunity to become strong enough to sustain
the increased effort required of them. One should never
run with the mouth open (§ 272).

240. Boxing is fine exercise but should never be in-
dulged in with the bare hands. Two pairs of boxing
gloves may be said to contain a whole gymnasium. Boxing
makes one sure and quick on his feet, trains the eye, keeps
the body in an erect position, develops the arms, legs, and
back, and teaches control of temper. Wrestling is equally
beneficial, developing the "wind" and the muscles of the
whole body. It should never be practiced in the house,
unless in a gymnasium, and where there is ample space
and no injurious objects to fall upon. Training in these
manly arts will make one " less likely to pay serious atten-
tion to idle bluster, and less likely to quarrel ; and it may
prove valuable to know how to defend oneself from the
attack of a ruffian, or bully, or drunken brute, or other
infuriated animal."

241. Cycling when properly done is excellent exer-
cise, but the cycler that gets a foolish notion of trying for
speed (and most of them do) usually brings on the deform-
ity of round shoulders.

242. Dancing, in itself, is said to be exhilarating
exercise. As usually conducted, indoors instead of out-
doors, prolonged to late hours, with overheating, and (in

142

ELEMENTS OF PHYSIOLOGY

the case of ladies) sudden chilling from insufficient clothing
in the region of the chest, this exercise has serious draw-
backs, and often wrecks the health of the participants.

243. Curative Effects of Exercise. —
"He who does not find time for exercise
must find time for sickness " (Lord
Derby). Many persons in declining health
have insisted on doing nothing but taking
the nauseous doses of patent medicines,
or the drugs of physicians, but not their
advice, and have died. But a little change
in the habits of life, such as adding to
their usually sedentary work a little
gardening, or wood-cutting, or raising
flowers, or horseback riding, or wood-
working, or pedestrian excursions, would
have restored them to health and enabled
them to live to a happy old age.

244. Exercise and Mental Ability. -
Most men who have been great workers
with their minds have also been zealous
in using their muscles. There is a flexi-
bility of mind and disposition that results
from a mixed occupation which is in great
contrast with the machine-like dullness and
narrowness of mind produced by a monoto-
nous, one-sided occupation, whether men-

FlG. 127. — The Veins i • i >-i i ^ i 11

near the Surface on tal or physical. Gladstone chopped down
trees ; Li Hung Chang walked three miles
v"^: daily, around the courtyards of his palace,

the Arm.

The fibrous sheaths when eighty years old ; Napoleon rode

covering most of the .

muscles have not been horseback ; William Cullen Bryant, upon

rising in the morning, swung a chair around

his head, took wand exercise with a cane, and practiced other

gymnastics. He walked five miles to his work. Talmage,

THE MUSCLES 143

when out for a walk in the park, would often run if there
was no one in sight. Philip D. Armour, many times a
millionaire, walked to his office while his clerks took the
street car.

245. Over-development of Muscles. — As important as
muscular exercise is for sending the blood bounding through
tha veins and renewing the health of every part, exercise
can be overdone. Some athletes develop great, heavy mus-
cles which are a burden to the vital organs to support.
They do not take care to develop their lungs and breathing
powers in proportion. Such athletes die young. Among
those who have succumbed to consumption may be men-
tioned Kehoe, the famous club swinger ; Dowd, the teacher
of physical culture; "Jap," the wrestler ; Winship, the
inventor of the health lift ; Kennedy, the strong man ; and
Peter Jackson, the pugilist (§ 238). Complete living with
conditions of health and activity for all the organs, without
extreme use of any of them, is most conducive to a long
and healthful life.

PROBLEMS AND QUESTIONS FOR REVIEW

1. In what part of the body are most of the involuntary muscles
situated?

2. Name a muscle which is wholly involuntary.

3. Can you name any muscle which is wholly voluntary under all
circumstances? To which class do the muscles that lift the eyelids
belong?

4. Which muscle, anatomically, belongs strictly to neither class?

5. If a man had absolute control over his muscles of respiration,
what might he do that he cannot now do?

6. Can the muscles act independently of the will in walking?

7. Do we shiver with the voluntary or involuntary muscles? Is
trembling usually involuntary?

8. How many movable bones are there in the face? Name muscles
attached to a movable bone of the face.

9. What purpose do most of the muscles of the face serve?

10. Why is one who uses alcoholic drinks not likely to be a good
marksman?

144 ELEMENTS OF PHYSIOLOGY

11. Why should a youth who wishes to excel in athletic contests
abstain from the use of tobacco ?

12. What order of lever is the foot when a weight is lifted on the
toes (Fig. 1 19) ? What order of lever do we use when we lift the leg
while sitting down ?

13. Locate the three points of a lever when swinging the arm from
the shoulder ; when bending a finger ; when tapping the ground with
the toes (Fig. 117) ; when using the foot in walking (Fig. 118).

14. Why can we raise a heavier weight with the hand when lifting
from the elbow than from the shoulder? (See Elementary Physics.)

15. Which bone is chiefly in motion when we are using a gimlet?

1 6. Why does using a muscle cause fatigue ?

17. Why can we chew harder with the back teeth than the front
ones? (See Physics.)

1 8. Why is it an advantage that the heel bone projects? That the
bones of the limbs are enlarged at the joints?

APPLIED PHYSIOLOGY
EXERCISE I

1. Does a few minutes1 practice in a gymnasium suffice for a day's
exercise ?

2. Is there any relation between the amount of bodily exertion
necessary for a person's health and the amount of wealth he possesses?

3. It is said that an Indian often runs or trots sixty miles per day,
and that he rests his muscles without stopping by running for a
while chiefly with the hip joint and muscles of the thigh, then with the
knee joint and muscles of the upper leg. Can you rest some of the
running muscles while running?

4. Can you relax the chewing muscles so that the lower jaw will
swing loosely when the head is shaken?

5. Can you relax the muscles of the forearm so that the hand will
shake loosely on the wrist and the fingers in their sockets ?

6. Can you relax the whole arm so that another person can move it
as a flexible rope ?

7. Which joints of the limbs lock and refuse to bend further when
the limb is straightened?

8. Which muscles have become useless with most persons, al-
though some can still use them (Fig. 122)?

9. The average man has 60 Ibs. of muscle and 2 Ibs. of brain : one
half of the blood goes through the muscles and one fifth goes through

•
THE MUSCLES 1.4.5

the brain. What inference may you draw as to the kind of life we
should lead?

10. What are the beneficial effects of exercise upon the functions of
the skin ?

11. Is a slow formal walk suitable exercise ?

EXERCISE H

12. How can we best prove that we have admiration and respect
for our wonderful bodies ?

13. What part of the body has the least bone in proportion to the
other organs? In what part of the skeleton is it most important to
keep the muscular walls firm and strong in order to hold the internal
organs in position ?

14. Which of your legs do you use more than the other in walking?
(The foot on that side is larger, as shown by the fit of the shoe.) If
you were lost on a prairie, to which side would you turn while trying to
go straight ?

15. How does the fact that if the nerves on one side of the face are
paralyzed the face will be drawn toward the other, illustrate muscular
tone?

1 6. Why does a game of baseball on Saturday afternoon actually
rest a tired plow boy ?

17. What movements did you ever see a cat go through for the
sake of exercise ? •

1 8. What animals have you ever seen play? Stretch themselves
for exercise?

19. Why do you feel so exhausted after a fright?

20. How do you account for the origin of the mental state, which
holds in practice if not in theory, that all physical labor is an unmiti-
gated evil?

21. Do you know persons who seem to be possessed by what is
called " the spirit of jerkiness " ? How could they overcome it (§ 227) ?

NOTES

i. Thought, Exercise, and the Blood. — Professor Angelo Mosso of
Italy devised a large balance on which the human body can be so poised
that a change in the distribution of blood can be detected at once.
If the body lies perfectly balanced on the apparatus, it is evident that
an additional supply of blood will cause the head to sink if the blood
goes to the head, or the feet to go down if the flow is in the opposite
direction. It is found that during study or mental work, the head

L

146 ELEMENTS OF PHYSIOLOGY

sinks in a very short time. Students balanced before and after written
examinations, showed that the center of gravity had risen from ^ inch
to 2 \ inches. W. G. Anderson, director of the Yale Gymnasium,
found that mere thought will send a supply of blood to parts of the
body. A man perfectly balanced will find his feet sinking if he goes
through leg gymnastics mentally but does not make the movements.
The flow of blood to an exercised part is affected by the attitude of mind
of the person exercising. If a man exercises in a listless, mechanical
manner, the center of gravity is not changed to any extent ; but when
a man takes a series of movements in a conscious and highly volitional
manner, the increase in the supply of blood to the arms or legs, accord-
ing to the movements taken, is very noticeable. If two men exercise
the arms and thorax, one standing before a looking-glass, the other not,
the former will show a greater rise of the center of gravity than the
other, or a richer supply of blood to the parts. The looking-glass aids
him in concentrating his mind on the parts exercised. Dr. Anderson
also finds that movements in which men take pleasure send blood more
abundantly to parts than do movements which are not to their liking.
These experiments furnish important conclusions as to the manner of
taking exercise, and the kind of exercise to be taken in order to obtain
the greatest benefit therefrom.

2. Unfortunately, the majority of human beings regard the necessity
of sweating as a calamity ; and to dodge sweating, to earn one's liveli-
hood in some other way, seems to be the special aim of a growing
multitude in all civilized lands. But sweating is a blessing in disguise.
The Scripture maxim teaches us that if any will not work, neither shall
he eat, — either from poverty or indigestion. Nature tells us, " They
who will not earn an appetite, cannot digest," and further she says with
equal emphasis, " He that will not work shall not sleep1' (J. H. Kellogg).

3. Effect of Exercise on Growth. — Henry G. Beyer, M.D.,
reported observations on the growth of 188 naval cadets who took
special systematic exercise, and compared it with the usual growth of
cadets of the same age.

There was an increase in height of more than one inch above that
which took place without the special exercise.

The increase in strength was five times as much as the normal
increase.

There was an increase in weight of 77 pounds in the four years during
which the observations were made.

There was an increase in lung capacity of 1.72 liters.

PART III. HOW THE BODY IS
NOURISHED

CHAPTER X

THE RESPIRATION

246. Why Breathing Organs are needed. — Every cell in
the body requires oxygen to enable it to do its appointed
work. When the supply of oxygen stops, the activity of
the cell ceases at once. If it is a muscle cell, motion can
be generated in the muscle only by the union of oxygen
with the contents of the cell. If it is a gland cell, it can-
not do its work of secreting useful fluids without the help
of oxygen, for the substances which the gland cell takes
from the blood must be changed to form the secretion. If
the cell is a brain cell, although it may not use as much as
a muscle cell uses, oxygen is still indispensable. The oxi-
dation that takes place in the various cells results in the
formation of carbon dioxid and other waste products which
would destroy the life of the cell if allowed to remain ;
these are removed from the body by the same organs that
supply the oxygen.

247. What must be the Nature and Structure of a Breath-
ing Organ? — It is obvious that in animals of large size
with many tissues, the great majority of the living cells of
the tissues must be buried deep away from the external
surface. But even if deep-seated and away from the air,
the living cells have the same need of oxygen as though

148 £L£M£NTS OF PHYSIOLOGY

near the surface. If oxygen is supplied to the blood, the
latter conveys the oxygen to the cells; but it is seen that a
very efficient organ is needed to supply the blood with oxy-
gen sufficient for so many cells. The breathing apparatus
varies in different animals ; it usually consists of a device
for exposing to the air a great amount of thin tissue, which
is a specialized form of the outer skin of the animal (if
the animal is not a land animal, the tissue is exposed to
the water) ; the animal is further provided with means to
keep up a current of air (or water) on the outside of this
modified skin and a current of blood on the inside. In
some small animals, as the ameba and the earthworm, the
simple external body surface is sufficient for the purpose
of breathing. But large animals with many deep-seated
and inaccessible cells require an increase of surface, which
is supplied by having the oxygen-absorbing surface inside
of the body and by having it folded or provided with tubes
or branches of the greatest degree of complexity. In man,
it has been estimated that by the finer and finer division of
the air sac, a pair of human lungs presents to the air a
surface of at least one hundred square feet (or ten feet
square). The remainder of the breathing apparatus' con-
sists of muscles for changing the air that is in contact
with this great surface.

248. Definitions. — The passing of the air into the lungs
is called inspiration, and the passing of the air out from
the lungs is called expiration. The two together constitute
respiration, or breathing.

249. Anatomy of the Respiratory Organs. — The air
usually passes in at the nose and returns by the same
way, except during talking or singing. If you look in
your mouth with a mirror, you will see at the back part
an arch which is the rear boundary line of the mouth.
Just above the arch is likewise the limit for the back part
of the nasal passages. The funnel-shaped cavity beyond,

THE RESPIRATION

149

into which both the mouth and nasal passages open, is
called \h.Q pharynx (far1 inks), or throat. Below, two tubes
open from the pharynx, one into the trachea (trdk'e-a)
or windpipe, the other into the esophagus, or gullet. At
the top of the trachea
(Fig. 129)13 the carti-
laginous larynx, or
voice box, and the
opening from the
throat is provided
with a lid, the epi-
glottis, also consisting
of cartilage. The lar-
ynx will be described
more fully in treating
of the voice ; it may
be felt as the Adam's
apple. Just below it
comes the trachea
proper which is a tube
about three fourths of FIG. 128.

an inch in diameter, I; largest cartilage of larynx; », lowest cartilage of

and about four inches %£&££*"* the divisions and subdivision$
long (Fig. 129). It

consists of hoops of cartilage which are not complete
circles but are shaped somewhat like the letter C, being
completed behind by nonstriated (involuntary) muscular
tissue (Fig. 130), whose function is to draw the ends
of the rings together at times, e.g. during coughing,
and reduce the caliber of the tube. The function of
the hoops of cartilage is to keep the windpipe open
at all times. If it should collapse under pressure, life
might be lost. These rings of cartilage may be felt in
the neck.

250. The lower end of the trachea is just behind the

ISO

ELEMENTS OF PHYSIOLOGY

upper end of the sternum ; and there it divides into two
bronchi, called the right bronchus and the left bronchus
(plural, bronchi} (Fig. 129). The bronchi subdivide into a
greatnumberof smaller
branches, called bron-
chial tubes. Cartilage
is found in the walls of
all but the smallest of
the tubes. The subdi-
vision continues until
the whole lung is pene-
trated by branches, all
having the general
name of bronchial
tubes (Fig. 128). The
smallest are only about
y1^- of an inch in di-
ameter. They ramify
through the lungs,
somewhat like the
branching of a tree,

FlG. 129. — The
chea (front) .

h, hyoid bone; /, tf, thy- " "*& * a> arytenoid cartilages; h,

cartilage; c, cri- f Unnel-Shaped Chamber hyoid bone; *, t', thy-

Tra- each tiny tube finally FlG- 130. -The Tra-

.. . .,v chea (back).

ending in a wider

coid; e, epiglottis; tr, 777 /T—

trachea; b and b', Called 3. lOOUle (Fig.
bronchi.

roid cartilage; c, cricoid,
<?, epiglottis; tr, trachea;
b and b1, bronchi.

131), into which so
many dilated sacs, called air cells, open that the walls of
the terminal chamber, or lobule, may be said to consist of
tiny cups, or air cells, placed side by side. (The word
" cell " is here used in its original sense to denote a
cavity or chamber, and not in the sense of a protoplasmic
cell.)

251. The wall of an air cell consists of elastic connective
tissue lined with a layer of very flat and thin epithelial cells
(Fig. 132). This lining is continuous with the epithelial

THE RESPIRATION

lining of the bronchial tubes. It is so thin as to offer almost
no obstruction to the passage of oxygen out of the cell and
the entrance of the carbon dioxid from
the blood vessel (Fig. 133).

252. Ciliated Cells. — It must be re-
membered that mucous membrane lines
all cavities in the body accessible to the
air. Almost all of the nose and pharynx,
and all of the air passages as far as the
lobules, are lined with a mucous mem-
brane the cells of which are furnished
with cilia (Fig. 134). These are minute
FIG. 131.— TWO Lobules at hair like filaments which are in constant
the End of a Bronchial motion. When a few of the cells are

Tube. .

examined under a microscope, we may
see the cilia in motion, even for a time after the removal of
the cells from the body. They make a quick stroke up-
ward, and move back more slowly, and this is found to
give them the power of moving particles of dust which
enter the lungs upward toward
the larynx. Upon reaching the
larynx, the dust brings about irri-
tation which causes it to be coughed
up. In the nasal passages, they
serve a similar purpose. At the
opening of the nostrils are also
placed ordinary hairs (hundreds of
times larger than cilia), which aid
in cleaning the air of dust as it
enters the nose.

253. The Blood Tubes in the Lungs. — Near where the
trachea divides into the two bronchi, the pulmonary artery,
bringing the dark blood to the lungs, divides into two
branches, and the subdivision continues, until, finally, a net-
work of capillaries is formed around each lobule, or cluster

FIG. 132. — The Wall of an Air
Cell.

*, the epithelium; t, partition be-

tween two air cells, in which the
capillaries lie; c, fibers of elastic

tissue>

152

ELEMENTS OF PHYSIOLOGY

a, network of capillaries; bt
small arteries and veins.

of air cells. These capillaries are the termination of the

branches of the pulmonary artery, and the beginning of the

pulmonary veins. It is here that the

blood changes from a purplish red to

a rosy red. A fine connective tissue

holds together all these air cells and

tubes.

254. The Lungs Entire. — The en-
tire cavity of the chest except the

space occupied by the heart and a few

of its blood vessels and the esophagus, FlG I33._The Blood Ves.

is filled by the lungs and their cover- seis around TWO Air Ceils.

ings. The lungs are light pink in early

life but become grayish and darker

as age advances. This change is more marked in persons

who dwell in large cities or where the atmosphere is smoky

and dusty. The lungs, or a part
of one, will float if thrown upon
water. The right lung has three
lobes, or divisions, and the left,
two lobes. The lower end, or
apex, of the heart hangs some-
what to the left, diminishing the
space for the left lung. The
general substance of the lungs
consists of bronchial tubes, blood
vessels, lymphatics, and air cells,
as above described, the air cells
being chiefly near the surface.

FIG. i34.— ciliated Ceils from the 255. The Pleuras. — The sur-

Trachea of a Rabbit, highly

magnified. face of the lungs is not in con-

m, m, mt mucous ceils in various tact with the chest wall. Imagine

stages of secreting mucus. , c .. .

a closed bag or sac made of thin

membrane lining the whole of the chest. Now imagine
another closed sac a little smaller, that is inside of, and

THE RESPIRATION 153

lining, the first one. Next imagine the lungs to be found
inside the inner sac. Here we have the lungs within the
two membranes, called the plenras. The heart is in the
chest, but is not inclosed by the pleuras. It is in a deep
indentation in the lower surface, such as you might make
in a paper bag by pressing your fist up into the bottom
without breaking the bag.

FIG. 135. — The Dome-shaped Diaphragm.

A, aorta; B, esophagus; C, vena cava inferior; Z>, muscular pillars of the diaphragm
arising from the spinal column E; F, ribs, and G, sternum, sawed through so as to allow
removal of the front of the thorax ; H, hind, and Kt front, muscular sheet, and /, central
tendinous part of diaphragm.

256. Use of the Pleuras. — The outer pleura lines the
chest wall, the inner pleura covers the lungs. The two
membranes form between them a closed sac, a serous cavity
which is air-tight and aids the lungs in following the chest
wall without friction when the chest expands. The two
pleural surfaces are in contact, and secrete just enough
fluid to enable them to glide smoothly upon each other.

154

ELEMENTS OF PHYSIOLOGY

But for the pleura there would be friction between the
lungs and the chest walls.

257. The Diaphragm (Fig. 135). —The floor of the
chest cavity is formed by a muscle that is the broadest in
the body, and also the thinnest in proportion to its width.
It is called the diaphragm. It rounds up under the concave
base of the lungs somewhat like a dome and separates the
thoracic and abdominal cavities. It is attached to the low-
est ribs at the sides and to the lumbar vertebrae behind
(Fig. 135). Its rounded side is turned toward the chest, and
its hollow side toward the abdomen. It is the most im-
portant muscle of the respiratory system. When it contracts,
it flattens and descends, and the lungs descend with it, thus

lengthening and enlarging the
cavity of the chest from top to
bottom.

When the diaphragm de-
scends, it acts as a piston or a
tight-fitting round board would
act if pressed down into a barrel
of water. If there were two
holes in the board (correspond-
ing to the vena cava and the
thoracic duct), the water would
be pressed up. Thus the circula-
FIG. 136.— Figure showing Three tion is aided by breathing. When

2M±£-Tia£ the diaPhrasra relaxes> its thin-

completing the Thoracic Wail. ness and flexibility would allow

A, sternum; B, rib cartilage; C, verte- ft fa drOD downward, instead of
bral column; F, rib; G, outer inter-
costal muscles; H, inner intercostal Springing Upward as pupils SOmC-

times suppose ; but the abdomi-
nal walls contract as the diaphragm relaxes and force the
liver, stomach, etc., against the diaphragm, thus pressing it
against the lungs (Figs. 137 and 138).

258. Other Muscles that expand the Chest. —The chest

—A

G'

THE RESPIRATION

155

walls can also be lifted out at the sides and in front. This
is accomplished by muscles leading from the shoulders and
spinal column to the outer surface of the ribs (Fig. 124),
and by the intercostal muscles, or the muscles that connect
each rib with the rib above (Figs. 136, 140). Thus the
chest may be made deeper from front to back and from
side to side, and if the diaphragm acts at the same time, the
chest is elongated from top to bottom, and thus is enlarged
in all directions.

FlGS. 137 and 138. — Diagrams to show the Positions in Respiration of the Ster-
num, Diaphragm, and Abdominal Wall.
A, inspiration; 3, expiration; Tr, trachea; St, sternum; D, diaphragm; Ab, abdominal

wall. The shaded part is to indicate the stationary air. The unshaded part shows the

increased air space during inspiration.

259. Inspiration. — The lungs themselves contain no
muscular tissue ; therefore they cannot expand by any
force of their own. Yet they expand when the chest ex-
pands. How does the enlargement of the chest cause the

156

ELEMENTS OF PHYSIOLOGY

lungs to expand, and the air to rush in ? The air cannot
be pulled in, for it has no cohesion, its parts do not stick
together. It is found that the air has considerable weight,
for the height of the atmosphere is at least forty miles, and
the air above is pressing down on that below. When the

chest walls are moved outward
against the weight of the outer
air, the space in the chest is in-
creased, and the air already in the
chest expands to fill the greater
space. The air, when expanded,
is lighter, and exerts less pressure
than before, and the denser air
outside, having greater pressure,
presses inward until the air in the
lungs is as dense as it was before
the lungs were enlarged. Thus
do we allow the air to come into
our lungs ; we do not draw it in,
but make space for it, and the at-
F,G. ,39. -Diagram of riand "osphere outside presses it in.

260. Expiration. — This is the

reverse of inspiration. The space

within the chest is diminished, and

^ ^ jn ^ } {& CQm ed

and becomes denser than the air
outside. This denser air has
greater pressure than the outside air, and presses out
through the air passages until enough has passed out to
restore the equilibrium, making the pressure equal without
and within (Figs. 137, 139).

261. But how are the Lungs made Smaller ? In ordinary
quiet breathing, the lungs become smaller, owing chiefly to
the elasticity of the parts involved. When the air rushes
in during inspiration, it enlarges the air cells by stretching

Seventh Ribs, in Connection

tion the Latter is carried

upwards and forwards.
The expiratory position is indicated

by continuous lines, the inspiratory

THE RESPIRATION

157

their walls, and the walls being made partly of elastic tis-
sue, the cells contract again when the muscles of inspiration
cease to act. When the ribs are lifted up during inspira-

tion, the costal cartilages
that connect them with
the sternum are slightly
bent, and the elasticity
of these cartilages, as
well as the weight of the
chest wall, causes the
ribs to become lower
when the muscles of
inspiration cease to act.

Many DUDils £T6t the QT-
"

TOnCOUS idea that the

Diagram to show action of intercostal muscles. At
A two ribs are represented in passive position. If
line ac shortens, the ribs will go down as in B.

If line bd shortens, the ribs will rise as in C. One . . , .

line represents an inner, and the other an outer, diaphragm IS alSO
intercostal muscle. A frame made with jointed cor-
ners (with strings to represent the muscles) will

4.* J

tlC aild

j
Upward

readily demonstrate the action of the two layers of When it relaXCS, thus aid-
intercostal muscles.

ing expiration. When

relaxed, it has no more elasticity than a piece of cloth,
and no more power to push itself upward. However,
the abdomen has been somewhat compressed, and its walls
somewhat stretched during the inspiration. When the
diaphragm relaxes, the elasticity of the muscular walls of
the abdomen presses the organs against the under side
of the diaphragm, pressing that in turn against the base
of the lungs, and aiding expiration.

262. Quiet or Passive Expiration is, therefore, a rebound
brought about by the elasticity of the air cells, costal
cartilages, and abdomen, and by the weight of the chest
wall. Active expiration adds muscular contraction to the
above forces. The two layers of intercostal muscles are
among those used in inspiration and active expiration
(Figs. 136, 140). The outer muscles diminish the spaces
between the ribs when they contract, and thus move the

158

ELEMENTS OF PHYSIOLOGY

ribs upward and outward (Fig. 140). (Place the hands at
the sides of the waist while inspiring, and this will be
noticed.) The inner muscles increase these spaces when
they contract, and thus depress the ribs and aid in expira-
tion (Fig. 137). In active expiration the abdominal walls
contract and press the abdominal organs against the dia-
phragm. By feeling the body, find the location of the
muscles that contract during strong expiration. Feel the
same muscles during the act of coughing.

263. THOUGHT LESSON. Ease in Breathing. — By study-
ing the skeleton of the chest (Figs. 59, 141), carefully
observing the bones and cartilages, and by experimenting
upon his or her own breathing, the pupil is to fill out the
following reasons why expansion and contraction of the
lower chest ("waist breathing") is easier than breathing
with the upper chest (" collar-bone breathing ").

1. There are two pairs of

ribs below, while there are none
above.

2. There are three pairs of

ribs below, while there are none
above, but all the ribs of the upper
chest are ribs.

3. The joints between the seven
pairs of true ribs and the sternum

are more flexible below because .

(Observe carefully Figure 141.)

4. In waist breathing the breaths

will not have to be so frequent to supply the same amount
of air, because the lower chest, besides being more flex-
ible, is than the upper chest.

5. The walls of the waist swing - - and while the

walls of the upper chest must move - - and - — .

6. The bones of the — — rest upon the upper chest.
In upper chest breathing their weight, and the weight of

FIG. 141.

THE RESPIRATION 159

both of the - — , must, therefore, be lifted. (Test by
experiment.)

264. Modifications of the Breath. — After studying the
following list and experimenting with your own breathing,
write after each word, I or E, according as inspiration or
expiration is chiefly involved in the action. Study each
action in other respects also : —

Sighing Coughing Sneezing

Sobbing Laughing Hiccoughing

Crying (of a child) Yawning Snoring

265. Air is composed of a mixture made up chiefly of
oxygen, nitrogen and a very small quantity of carbon
dioxid. Nitrogen is colorless, tasteless, and odorless ; it
does not support combustion, and is one of the most
inactive gases known to chemists. The oxygen of the
air is also colorless, tasteless, and odorless, but is one
of the most active gases known to chemists. The air
exhaled contains about the same amount of nitrogen as
that inhaled, but it contains much less of oxygen, the latter
having been replaced by an almost equal quantity of carbon
dioxid.

266. One Hundred Parts of Pure Air contain about 20
parts of oxygen, nearly 80 parts of nitrogen ( and other
gases), and .004 of a part of carbon dioxid. Air com-
ing from the lungs contains 16 parts of oxygen, nearly
80 parts of nitrogen, and over 4 parts of carbon dioxid.
The air while in the lungs has lost four parts of its oxygen,
there has been no change in the quantity of nitrogen, and
it has gained four parts of carbon dioxid. The oxygen is
in the air in order to supply an element to animals essential
to their activity. The nitrogen in the air is not used in the
body. The small amount of carbon dioxid in the air sup-
plies the plants with carbon. Its quantity is being constantly
added to by fires and by the breath of animals. The leaves

160 ELEMENTS OF PHYSIOLOGY

of plants, aided by the sunlight, are constantly removing
it, so that it is kept at .004 of one per cent in the air. If
it increases in the blood greatly beyond the usual amount,
dullness of mind and finally unconsciousness result.

267. Foul Air. — Besides the carbon dioxid, the air
coming from the lungs contains a small and variable quantity
of water and of foul-smelling vapors. In the air of a closed
room in which several persons have been for some time,
there is a characteristic odor which belongs to man, just as
there are odors peculiar to each of the lower animals. The
odors are caused by fine organic particles from the skin
and lungs of the persons. When a number of human
beings are together, and the ventilation is imperfect, the
air becomes very oppressive and is called " crowd poison."
Although it is given off by the cleanliest and healthiest
persons, the " crowd poison " accumulates faster if indi-
viduals in the room ( whether it be church, school, parlor,
or theater ) have catarrh, decayed teeth, or some other
diseased condition. The necessity for breathing and ven-
tilation is just as great, because of these organic particles,
as it is for the purpose of preserving the proper propor-
tion of inorganic elements in the air. Headaches and
other symptoms of distress, caused by ill-ventilated rooms,
are to be attributed chiefly to the effects of the " crowd
poison " upon the nerves.

268. THOUGHT LESSON. Protective Instincts: Effects
of Tobacco on Lungs and Habits of Life. — i . Chemical
analysis shows that there is enough nicotine in one cigar
if taken into the system, to kill two men. Does the expe-
rience of tobacco users disprove this ?

2. Name, in four words, four disagreeable effects that
soon follow smoking a pipe or strong cigar for the first
time.

3. Name two qualities belonging to tobacco that God
has given it in order to teach us through the senses that

THE RESPIRATION

161

it is not good for us and that we should not try to
use it.

4. What change does God cause to come over our in-
stinct to avoid harmful things if we disregard the warnings
as if they were from an unwise source ?

5. What means have shrewd manufacturers provided so
that even children now learn to smoke so gradually as not
to awaken the instinctive repugnance to the poison in
tobacco ? What aids in learning to chew tobacco ?

6. What injury results from chewing tobacco that does
not result from smoking ? What injury results from smok-
ing that does not result from chewing (§ 284)?

7. Where has the smoke been that a boy blows out of
his nose ? What does such a boy usually smoke ?

8. Give several reasons why weak tobacco smoke in the
lungs does a far greater amount of injury than strong
tobacco smoke in the mouth.

9. Why do cigarette smokers usually inhale, or draw
the smoke into the lungs, while cigar smokers do not ?

10. Think of three boys (without writing their names)
whom you know that do not use tobacco, and of three that
smoke cigarettes habitually. Fill out the following table,
placing the boys in two classes, and showing how many
of the three tobacco users are fleshy, and how many
are thin, etc. ; how many of the three abstainers are
fleshy, how many of the three are thin, etc.

I

£

M

Pale or
sallow.

Studious.

1

Obedient.

>,

|
&

Full sized.

Stunted.

3 tobacco users,

3 abstainers,

1 62 ELEMENTS OF PHYSIOLOGY

269. Subjects for Compositions. — The Benefits and Dis-
advantages of Bicycling. Natural and Artificial Beauty.
My Personal Observations and Experiences in the Light
of Physiology. Natural Cures and Medicines. The
Breath. Tobacco. Alcohol and Crime. Tight Shoes.
Sketch of the Life of a Friend. Exercise. The Lungs.
The Cigarette Habit. Health and Happiness.

CHAPTER XI
HYGIENE OF RESPIRATION

270. Dust. — The cilia of the air passages stop most of
the dust before it reaches the lungs, but not all. If the
dust is excessive, millions of particles enter the lungs. If
a housekeeper would examine the air of the room with a
beam of light reflected by a mirror during the time of
sweeping, she would often be horrified, and would heed
the caution of those who say that every door and window
should be opened before beginning to sweep, and allowed
to stay open for two hours afterward. If there is a
breeze, so much the better ; it blows the dust out,
especially if she sweeps in the direction of the breeze. It
is the presence of dust floating in the air, more than
fragments of trash upon the floor, that makes a dirty
home.

271. When a carpet is swept, dust comes from the carpet
itself, especially if it is old. Curtains and hangings also
hold dust. Hardwood floors, with rugs instead of carpets,
are recommended, and oilcloth and linoleum are also
excellent substitutes for carpets. Rugs can be conveniently
cleaned at any time, and the floor can be cleansed with a
moist cloth. Statistics indicate that among civilized races
a large proportion of the deaths is due to lung diseases.
This proportion is frequently estimated as high as one
seventh of the entire number.

272. Reasons for breathing through the Nose. — (i) On
account of the projections of the turbinated bones and
processes into each nasal passage and the round-about way

163

164 ELEMENTS OF PHYSIOLOGY

the air takes in passing through the nose instead of the
mouth, nasal breathing brings the air in contact with a
much larger extent of moist and warm mucous membrane
than does mouth breathing. The air becomes warm and does
not, like cold air, irritate the trachea and bronchial tubes.
(2) The air becomes purified, because the hairs just within
the nostrils and the mucous lining of the latter serve to
catch particles of dust, and the mucus has the power of
destroying germs. (3) While a mouth breather is eating,
sufficient time is not taken for chewing the food, but it is
swallowed too soon, so urgent is the necessity for breathing.
(4) In the habitual mouth breather,
the nasal mucous membrane, from lack
of stimulus of the cold air, dries and
shrinks, causing discomfort ; and since,
in its dry condition, the circulation
easily becomes obstructed, there is a pre-
disposition to congestion and catarrhal
nasal affections and injury to hearing.
FIG. 142. -The Facial EX- (5) An unpleasant expression of the

pression when breathing .

through the Nose and f ace results from mouth breathing (Fig.
when breathing through I42) the lower jaw recedes, the upper

the Mouth. J

teeth project, the nostrils are not devel-
oped and in a grown man may be no larger than during
childhood. (6) A person has greater endurance in mus-
cular exertion if he breathes strictly through the nose.
He can hold out much longer, his lungs are kept more
expanded, and the heart is not oppressed ; and, after
a while, a "second wind" comes to him, — for instance,
during running. (7) The voice has more resonance if the
nasal passages are open.

A Scotch physician, fully appreciating the importance of
proper breathing, has written a valuable medical paper,
entitled, " Shut your Mouth and Save your Life." Some-
times the cause of stopping up the nose in children is

HYGIENE OF RESPIRATION 1 6$

enlargement through glandlike growth of a structure in
the upper part of the pharynx called the third tonsil. It
is just behind the posterior openings of the nasal passages,
and can be easily removed if it becomes enlarged. Per-
sons who sleep with the mouth open are likely to snore,
and the mouth and throat are always dry in the morning.

273. Do the Breathing Muscles rest? — Expand your
lungs, and see whether they will contract of themselves.
Contract your lungs and see whether they will expand of
themselves. See whether you can make waist, chest, and
abdomen expand at the same time. You learned that the
periods of rest taken by the heart muscles amount to how
many hours daily ? The breathing muscles also rest a con-
siderable portion of the time ; with calm and happy people
they rest more than with people of anxious, unquiet disposi-
tions. We can breathe by means of the expiratory muscles
alone or by means of the inspiratory muscles alone, or by
using each set alternately. When all the breathing muscles
are relaxed, the lungs are at rest in what may be called the
neutral position, since there is neither voluntary contrac-
tion nor expansion. In this position they are of about aver-
age size. If now we use the expiratory muscles and contract
the lungs, the muscles may relax during inspiration which
follows, for it will be accomplished by the elasticity of the
abdominal walls and organs, and of the cartilages of the
thoracic cage ; for these were bent when the cage was
pulled from the neutral position. Try this method of
breathing for a few minutes.

274. Or, on the other hand, when the lungs are at rest
we may breathe by using the inspiratory muscles (Fig. 139)
(diaphragm, external intercostals, etc.), thus expanding the
lungs from the neutral position, and allowing the muscles
to rest, while the elasticity of the parts forces out the air.
Try breathing in this way.

275. This expanded breathing has the advantage over

1 66 ELEMENTS OF PHYSIOLOGY

contracted breathing, of removing pressure from the heart
and large blood vessels in the chest, and allowing the heart
to work with greater freedom. It also keeps the lungs
more expauded. You learned in another paragraph that
it is the usual method of quiet breathing; but strong,
contracted breathing sends out fouler air from deep in the
lungs.

276. In both of these ways of using the breathing mus-
cles, there is a pause in the neutral position before the
next breath. But in a time of great exertion, as when
running, or during a time of excitement and in some forms
of illness, there is no pause between breaths, and we use
what may be called continuous breathing. Both when ex-
piring and inspiring, the ribs are pulled on beyond the
position at which they rest. Thus the use of the breath-
ing muscles is continuous, and it is no wonder that they
may get so tired that they almost refuse to work for a
moment, and we are "out of breath," as we say. The
heart is thumping so fast and strong that the corpuscles
are shot through the lungs with unnecessary speed and do
not get even as much oxygen as they would if going more
slowly. Continuous breathing is a wasteful method ; haste
makes waste of strength, although it may seem to be
necessary in an emergency. You can really accomplish
more by quiet, steady work. Anxiety and worry, as well as
great physical exertion, cause this hurried, wasteful breath-
ing ; hence we should cultivate the easy way of breathing.

277. Reasons for Strong Expiration and Inspiration.—
Purifying the air in the lungs may be illustrated by dipping
dirty water out of a barrel and replacing it with clear water.
If a dipperful of clean water is poured into the barrel and
the same amount of water is dipped out, this will cause the
cleanest water to be at the top, whence it will always be
dipped out and the dirtiest water will be left. It is the same
way with the lungs ; the purest air in the lungs is always

HYGIENE OF RESPIRATION

I67

removed by breathing, but if the lungs are contracted by
strong and long expirations, more air from deep down in
the lungs, and therefore fouler air, is removed. When the
lungs expand fully, their surface is increased and every
little air cell is opened, helping the exchange of carbon
dioxid and oxygen through the thin walls.

278. You have just been studying about the three
methods of breathing according as you use (i) the inspira-

FiG. 143.

FIG. 144.

FIG. 145.

Diagrams illustrating Proper and Improper Methods of Breathing.

Dotted lines show area of expansion.

Fig. 143. — Female figure encased in corset. Expansion at the waist is here impossible
and the breathing is called " collar bone breathing."

Fig. 144. — Male figure. Here, owing to pressure of clothing and faulty position, expan-
sion of chest is impeded and breath is taken by the " diaphragmatic method."

Fig. 145. — Figure properly poised and free from constriction. Here the entire thorax
can move freely and normal breathing is the result.

tory muscles, (2) the expiratory muscles, (3) both. The
breathing may be varied also by the activity of the muscles
prominent in (i) the abdomen, (2) the chest, (3) both.
This gives rise to —

279. Abdominal Breathing, Chest Breathing, and Full
Breathing. — See whether you can make waist, chest, and
abdomen expand at the same time. See whether you can
make waist, chest, and abdomen contract at the same time.

1 68 ELEMENTS OF PHYSIOLOGY

There has been much discussion among physicians, voice
trainers, and elocutionists as to the proper way to breathe,
some advocating chest breathing (Fig. 143), and some ad-
vocating abdominal or diaphragmatic breathing (Fig. 144).
The fact that so elementary a process as breathing is still
a subject of discussion illustrates how imperfect is the
state of our physiological knowledge, especially when
an attempt is made to apply it to practical purposes. The
author believes that pure chest breathing and diaphrag-
matic breathing are both wrong, and that what may be
termed full breathing is the natural and best way (Fig. 145).

280. Full breathing employs movement of both chest
and diaphragm, the greatest expansion being in neither

Chest n°r abdomen> but at
the waist, and diminishing in

amount both upward and down-
ward. The objection to pure
chest breathing'^ that the marked

m°vement °f the upper part °f

the bony caSe recluires exhaust-
4. MAN IN CORSET mg effort ; such movement can

be employed without waste of
strength for only a short period,
as in gasping for breath _or
REFORMED CORSET WEARER during great muscular exertion

FIG. l46.-BreaThing Tracings (5 263> Yet Some women with

(Kellogg). waists confined by tight clothing

Motion of chest recorded at left and of breathe in this way f or hours at a

waist at right. tjme . thus their strength WCarS

out, and they are old before their time (Fig. 146).

281. In full breathing, the diaphragm contracts but at the
same time the ribs are lifted upward and outward, and the
points of attachment of the diaphragm are thus raised and
separated so that the diaphragm flattens without any great
descent. But in pure abdominal breathing, the movement

wou, CORBET

HYGIENE OF RESPIRATION 169

is confined to the diaphragm and abdomen, and lateral
action of the chest is suppressed. The effect of this is to
cause too great a displacement downward of the liver,
stomach, kidneys, colon, and other organs. But in nor-
mal or full breathing, any great degree of downward
movement is prevented by expansion of the trunk at the
waist. In abdominal breathing, the abdominal walls are
entirely relaxed as the diaphragm descends, and the
liver and other organs are moved but not compressed.
In full breathing they are compressed and slightly moved,
and the compression squeezes the blood out of them
toward the heart and presses the lymph upward through
the thoracic duct; the expansion of the chest at the
same time helps to draw the blood upward. During
expiration fresh blood is sent back to the abdominal
organs, and so they are kept fresh and strong. Ladies
who wear skirts with bands tight enough to support them
at the waist, and men who support their trousers by buc-
kling them around the waist, gradually lose the power of
lifting the ribs outward at the waist. This expansion is
most important for good breathing, because the lungs are
largest there.

282. Effect of Alcohol upon the Lungs. — It was learned
that alcohol paralyzes the vasomotor nerves, or those
that control the size of the blood vessels. This allows the
smaller arteries in the lungs to swell and the capillaries to
become congested, crowding upon the air cells and diminish-
ing the breathing power of the lungs, as is readily shown by
the use of the spirometer, a simple instrument which, when
the breath is blown into it, measures the number of cubic
inches the lungs expand. The continual congestion of the
lung tissue results in an abnormal growth of connective
tissue fibers in the walls of the cells ; the walls thus be-
come thickened and hardened and obstruct the absorption
of the oxygen and the escape of the carbon dioxid. Besides

I/O ELEMENTS OF PHYSIOLOGY

this, alcohol injures the red corpuscles, causing them to
shrink and impairing their power to receive and carry oxygen.
All these changes diminish the oxygen in the blood. This
state of blood is plainly shown in the purplish face of the
drunkard, crowded with enlarged veins. The weakened
power of breathing explains why a man given to drunken-
ness cannot endure vigorous muscular exertion so long as
can a healthy person.

283. The injurious effects described readily explain
why the consumption that attacks inebriates is a very
rapid and fatal form of the disease.

•284. Effect of Tobacco upon the Respiratory Organs. —
The hot smoke irritates and dries the mucous membrane
of the mouth and throat, producing an unnatural thirst
that may readily lead to the use of alcoholic drinks. In-
haling the poisonous smoke, which occurs to the greatest
degree in cigarette smoking, inflames the delicate mucous
lining of the bronchial tubes and air cells. There may
result from this an irritating cough, short breath, and
chronic bronchial catarrh.

285. Ventilation. — The evil effects of re-breathing air
can hardly be exaggerated. The blood stagnates, the
heart acts slowly, the brain is clogged, the head aches, and
either a dull or a feverish feeling arises. The body
becomes sensitive to cold. The skin becomes pale, the
blood is loaded with impurities, and the whole body is ob-
structed with refuse material. In such a human body,
colds, catarrh, consumption, and other diseases readily
develop. The constant breathing of even the slightly
impure air of most private houses cannot but tend to
undermine the health and prevent that perfect soundness
of body which thorough ventilation or life in the open
air insures.

286. Judgment with regard to ventilation is rare. In
many churches and assembly rooms the windows are tightly

HYGIENE OF RESPIRATION 171

closed except in warm weather. If, during the meeting,
the room becomes too warm (not if it becomes foul with
impure air), some one will open one or more windows to
their full height ; the strong draught soon cools the room
and chills some one, whereupon he goes to the window
and shuts it tight. One absurd extreme thus follows
another. All that was necessary, if there was no scien-
tific provision for ventilation, was for all of the windows
to have been opened, for an inch or less, when the as-
sembly began, and allowed to remain so ; then no one
would have been too hot or too cold, or would have
suffered from foul air.

287. What is the probable cause of persons fainting
or going to sleep in church ? With the foul air was
combined what other disadvantage to breathing, as shown
by one of the measures often taken to restore a person in
a faint, especially if a woman ?

288. The ventilation of the schoolroom is often deplor-
able. A visitor, upon entering a schoolroom, especially
if the school has been in session for an hour or more,
may notice a stifling, foul-smelling atmosphere. The chil-
dren have rushed in from their active games with their
clothing saturated with perspiration. Their healthy skins
perspire more freely than do those of adults. Some of
them may have coughs or colds, and sometimes come
from sick rooms.

289. Carbon monoxid forms in the stove if the draught
is closed too much, and escapes through cracks and seams
in the stove, and, if the stove is red-hot, through the iron
itself. Carbon monoxid is different from the dioxid in
being imperfectly oxidized, and its attraction for oxygen
causes it, when breathed, to attack the red corpuscles of
the blood causing headache and dizziness, for the mon-
oxid is an active poison, not merely negative like the
dioxid. The ashes from the stove, the dust from the

1/2 ELEMENTS OF PHYSIOLOGY

pattering of many feet, the clouds of chalk dust, accumu-
late until they become almost unbearable, and all that gets
out leaves the room on the clothes of the pupils, or on the
mucous membrane of their nasal passages, windpipes, and
lungs; for the janitor is more ignorant than the house-
keeper, and he likewise will not open the windows before
sweeping because of the trouble ; or, if persuaded to open
them, he must be compelled by the principal to allow them
to remain open for the dust to blow out, otherwise he
will close them on leaving each room to avoid the annoy-
ance of returning.

290. These are the conditions of many, many school-
rooms and houses, for, unfortunately, some persons' knowl-
edge of physiology consists largely of a knowledge of big
names. It is not strange that lung troubles are rife, and
that people wonder whence they come, and take medi-
cated gases instead of pure air. Many of the Indians
of Patagonia died of consumption within nine months
after being taught by the missionaries to live in houses.

291. It is necessary to give children knowledge of the
geography of Africa and other remote lands, but it is at
least as necessary to train them to sit and to stand
correctly. Interruptions to study every half hour by calis-
thenic exercises so selected as to give vigor to those
muscles that counteract the evil, deforming effects of pro-
longed sitting, would help them to grow up well-formed
men and women, and would aid in learning the geography
as well.

292. The health of children at school often suffers, and
parents usually think it is because of the number of studies.
This idea is no doubt largely erroneous. The breathing of
the bad air, both at home and at school, the close confine-
ment in the schoolroom, sitting in a cramped position,
and studying by improper light, are the true causes in
a majority of cases.

HYGIENE OF RESPIRATION

173

293. Some persons in their anxiety for pure air become
extremists, and forget that the body may likewise be in-
jured by cold. In ventilating a room, not one but two
purposes must be kept in view : to furnish air that is pure,
and air at the proper temperature.

294. Methods of Ventilation depend upon the principle
that hot air is lighter than cold air and is pushed up by
it. If you have two openings for ventilation, one higher
than the other, at which opening does the warm air
go out ? If the

higher opening
is near the ceil-
ing, do the per-
sons in the room
get the coldest or
the warmest air?
Does such a
method econo-
mize the fuel?
If the inlet is
near the floor,
why should the
stove be near

FIG. 147. — The Proper Method of ventilating a Room.

The stove is on the side toward the cold winds. The inlet is
near the stove, the outlet farthest away. If the window near
the stove were lowered from the top, what would probably
happen? If another window near the stove were opened,
what might happen? If the prevailing cold winds came from
the opposite direction, what changes should be made in the
room? How do you ascertain whether the outlet fails to serve
its purpose and becomes an inlet?

the inlet ? Why should the outlet be on the side of the
room farthest from the stove ?

295. Good ventilation is arranged so that the fresh air
shall be heated before or just after it enters the room, and
that it shall pass across the room in order that the in-
mates may get the benefit of both its warmth and its purity
before it passes out (Fig. 147). Test the direction of the
air currents in your bedroom and in your schoolroom by
means of a spider web hanging from the end of a stick.
Why is it best not to have the outlet on the side of the house
toward the prevailing wind in winter ? If the inlet is so
situated that the cold air does not pass over the stove, a

174

ELEMENTS OF PHYSIOLOGY

FIG. 148.

board or a screen may be placed before the window to

deflect the current upward and prevent its chilling those

seated nearest the window (Fig. 148). If you find by
holding your hand near the inlet that there is
a good inward current, you may be sure there
is sufficient outlet; although if it is not far
enough from the stove, heat will be wasted.
If you know there is a strong outward cur-
rent, for instance, when a fire is burning in an
open fireplace, you may be sure that the
same amount of air is ' entering somewhere,
if only through minute cracks (Fig. 150).

296. When over-enthusiastic people become
interested in ventilation, they sometimes in-
jure themselves by chilling draughts and low
temperatures. The temperature of the room
^ou\d be kept between 65 and 70 degrees.
wooden strip at a. The foregoing directions for ventilation apply

to cold weather. For warm weather no special directions

are necessary, for most people are more unwilling to bear

unpleasant heat or to soil their

collars with perspiration, than

to breathe foul air.

297. The Five Degrees in

Cleanliness. — Nearly all peo-

ple are very careful to wear

clothes that are perfectly neat

and clean. Dust or mud upon

their clothes is considered the FIG. 149. — Gallon's Fire Grate.

highest degree of uncleanli- With a Pasusase bejind. the grate that the

air may be heated as it enters.

ness. Many think it of the

highest importance to health and refinement to keep the
skin clean by regular baths. But there are a few that
think it of still greater importance to keep the air clean
that goes into the lungs. A few also think it necessary to

a-*

HYGIENE OF RESPIRATION

175

keep the alimentary canal pure throughout by reasonable

eating and living. We also meet with those who believe

not only that the clothes, the skin, the lungs, the digestive

organs, must be kept clean, but

that the blood must be clean and

fresh, ever renewed by a strong

and vigorous flow, and they so

live that as far as possible it

shall always be so. The daintily

dressed lady or the dandified man

would be horrified at a particle

Of mud that fell Upon the Clothes, Fia I50._ Ventilation by an Ordi-
but Sometimes if yOU are SO Un- nary Grate or Fireplace.

fortunate as to catch a whiff of The coldest air chills the feet-

the breath of such a person, its repulsive, sickening odor
shows that foulness and uncleanliness
have taken possession of the lungs, or
digestion, or blood. We should be
careful to observe these five degrees
of cleanliness, but which should we
value most highly ? There is still
another degree in cleanliness, or pur-
ity, which concerns purity of mind
and nobility of soul.

298. The Mistake of the Overstu-
dious. — The pale student, thinking
only of the desire for learning aroused
by teacher or parents, and neglecting
the promptings of his natural instincts
toward complete living, thinks he is
doing wisely and right when he is
constantly delving into books. On
the contrary, he is sinning against

part of his nature and unfitting himself for accomplishing

the best work he is capable of doing.

FIG. 151.

The air enters through a special
inlet and is warmed as it
passes through a hood sur-
rounding the stove.

176 ELEMENTS OF PHYSIOLOGY

299. Consumption, or Tuberculosis, is a disease due chiefly
to living constantly in unventilated houses. That the
natural curative powers of the body are capable of curing
consumption, is shown by the fact that reports of post-
mortem examinations in some of the hospitals of the
United States and Europe show scars on the lungs in half
of the cases examined. These scars were left by con-
sumption, which the persons had had without knowing it or
being treated for it, and from which they had entirely re-
covered, dying afterward from another disease. These
facts show that in the early stage consumption is an es-
pecially curable disease. Persons are sometimes alarmed
because they have heard that consumption is caused by a
bacillus, or microscopic germ, commonly called a microbe.

300. That it is not caused by microbes alone is proved
by the fact that the microbes are floating in the air, and
nearly all human beings are exposed to them many times
in their lives, yet all do not contract the disease. Consump-
tives are constantly spitting on the streets of cities, yet a
smaller percentage of the street cleaners of Berlin than
of almost any other class of the population die of con-
sumption.

301. Outdoor life, simple diet, and exercise seem to be
the best treatment. Inhalations through apparatus of
medicated air, moist air, dry air, cold air, superheated air,
air charged with the pleasant aroma of pine leaves or the
repulsive sulphuret of hydrogen, have all been tried. It
seems impossible directly to destroy the microbes when
they once obtain a foothold in the lungs, without the
employment of such measures as will destroy the lung
tissue as well as the parasitic bacilli. Even if the bacillus
could be destroyed by germicides, it would be impossible,
since the germs are so widely scattered, to escape infection
again, and the disease would return for the same reason that
it first gained a foothold : this was because, from indoor

HYGIENE OF RESPIRATION 1 77

life, shallow breathing, indigestion, lack of exercise and
fresh air, the blood had become impure and the lung
tissue so corrupted and weakened that it furnished a fer-
tile soil for the growth of the germs. (Read note 2, page
191.)

302. Subject for Debate. — Resolved, That the Chinese
woman has less love for personal deformity than the Cau-
casian woman and suffers less from it.

BACTERIA AND DISEASE

303. Nature of Germ Diseases. — A plant, as an oak or a
pear tree, may become affected by a disease called the
blight, and such disease is usually regarded as a necessary
evil, or an imperfection in creation. Looked at with a
broader knowledge, such disease is a sign of growth as well
as of decay and is a blessing and not a curse. The micro-
scope shows that trees affected with the blight are the seat
of the growth of millions of one-celled plants called bacteria.
So where there is death and disease, there is flourishing
life. The blight did not attack the hardy, sound pear
trees, but those of rapid, sappy growth whose tissues had
already become injured or dead by the effect of frost or
some other agent. The function of the bacteria is to de-
stroy unsound vegetable or animal matter by living upon it
as food, thus decomposing it and returning it to the soil
and the air to be used again. There is no decay without
the action of bacteria; without it organic matter would
accumulate indefinitely, interfering with life upon the
earth.

304. Molds. — Every one has seen fungus plants, such as
mushrooms and puff-balls, that do not bear flowers but mul-
tiply by spores. They live upon dead logs or where there
is much dead organic matter in the soil. Imagine a fun-
gus that grows on an average about yj-g- of an inch in

178 ELEMENTS OF PHYSIOLOGY

height; this is called mold (Fig. 152). It grows, for
instance, upon moist bread in warm weather. Mold forms
a kind of network as it grows through any substance that
N will nourish it, and sends up stalks with
knoblike ends, the knobs being full of
minute spores.

305. Yeast — Think, if you can, of
small plants only about ^ for of an incn
in length, composed usually of one oval
cell, a plant that makes new plants by
"budding," or the forming of a smaller
FIG. 152. — Ring- cel1 on tne olc* one. Yeast cakes consist
worm Fungus in a of yeast plants scattered among the grains

wiif Fig.(^mpare of flour of which the cake was made-

Yeast plants multiply rapidly, doubling in
number in two hours (Fig. 153). They grow upon sugar,
decomposing it into alcohol and carbon dioxid. This pro-
cess is called fermentation. In wine making, alcohol is the
product sought; in bread making, carbon dioxid
is the useful product, this gas giving the bread
its lightness, while the small amount of alco-
hol formed is driven out by the heat in
cooking.

306. Bacteria. — But suppose the micro-
scope shows a much smaller vegetable organ- FIG. 153. — The

.. , r • L • Yeast Plant-

ism which averages ^oWoo" °f an mc^ m

diameter and is a one-celled vegetable that multiplies by
division like the ameba and other one-celled animals, and
lives upon albuminous substances only for its food. This
is a bacterium. Bacteria are called also microbes or
germs ; and they are the smallest of living organisms. A
bacterium that is rod-shaped is called a bacillus (Fig.
154). Under favorable conditions — abundance of food
and considerable warmth and moisture — bacteria may
double in numbers every half hour. Thus millions may

HYGIENE OF RESPIRATION 179

result from even one in a short time. (You will compre-
hend this better by referring to "geometrical progression "
in your arithmetic.) Dryness and cleanliness prevent their
growth ; cold retards their growth and division, hence the
utility of ice in preserving meat, milk, fruits, and other
foods in warm weather.

307. Can you now arrange the names yeast, mold, and
bacterium in order of size ? Can you

give the kind of material that each
uses for food ? Can you tell how each
multiplies, or reproduces its kind?
What is a bacillus ? For what is " mi-
crobe " another name ?

308. Use of the Small Organisms. —
Molds are nature's tools for destroying

hard and durable tissue like, logs, bone, FIG. 154. — Bacilli; the
and hides, which otherwise would not fame S,peci? masni'

fiedtoTwo Sizes.

decay but would fill the earth, leaving
no room for living creatures. Ringworm is caused by
the growth of one form of mold within the skin. It does
not grow in a sound and clean skin. Falling of the
hair is often accompanied by the growth of mold in the
hair follicles, but it must be preceded by overheating and
starving of the cells of the scalp by a tight hat, too much
brain work, or other cause (Fig. 152). Yeast prevents
the calamity of all plant food accumulating in the form
of starch and sugar. Bacteria destroy the dead and excreted
matter of vegetables arid animals so that it melts away and
is stored in the soil, ready to be utilized as plant food
again. Mold, yeast, and bacteria are great blessings, for
they are indispensable friends of all other living beings
(Fig. I55>

309. Their Work in the Body. —They do not always wait
for the dead or dying material to be excreted, or separated
from the animal or plant, before attacking and destroying

ISO ELEMENTS OF PHYSIOLOGY

it. If more food is eaten than can be digested, and it
remains longer than five hours in the stomach, starchy food
may ferment from yeast plants, giving rise to carbon dioxid
gas, and albuminous food may ferment from bacteria, or a
moldy growth may form on the lining of the organs, extend-
ing up to the mouth
and forming a coat
upon the tongue. If
the lungs are never
fully expanded, but
by stooping over at
work or by tight
clothing a part of the
lungs is compressed

j yy§jS^j5| ^ and the blood supply

QOQ " 25°C interfered with, or if

FIG. I55.-Shown by Microscope of High Power. f°ul air is Constantly

A, white corpuscles are seen creeping up a tube and devour- breathed, impurities
ing bacteria which appear as minute specks. maV Collect in the

B, a drop of water containing infusoria. The clump in the *

middle has been killed by the touch of a hot needle, the lungS and the baC-

others are fleeing from the dead bodies. . . , ••

C, a capillary glass tube containing bacteria. One end is tCHa are On the alert
heated to 25° C, the other end cooled too0 C. The bac- to remove them The
teria have crowded to the warm end.

bacillus tuberculosis

is the form of bacteria that usually finds lodgment in the
lungs.

310. As the bacilli multiply tiny tubercles are formed ;
hence the name. Tubercles are growths shaped like pin
heads, and they may be formed in any tissue of the body.
An attack of consumption is usually preceded by indi-
gestion and imperfect nutrition of the body. You have
learned that in thousands of cases bacilli remove an injured
part of a lung and it heals over. But in thousands of cases
the individuals have lived wrong physically for so long,
and their lungs have become so weak, that they are
gradually destroyed by the bacilli. This is sad to the

HYGIENE OF RESPIRATION il

individual and his friends and loved ones, but it is best
for the race, for it prevents gradual degeneration into a
race of weaklings.

311. Whether the body has been injured through ig-
norance or self-sacrifice, through dissipation or selfish am-
bition for money or fame, through foolish attempts at
beauty or through devotion to learning, or through unselfish
love and work for others, the result is the same ; nature
knows no difference. However noble the character or wise
the mind (in other directions), when a vital organ has sunk
in health below the standard necessary for a human being,
condemnation comes.

312. Bacilli are usually found in the sputum only in an
advanced stage of consumption. Then recovery is more
difficult, but it will often come if the person returns to
natural ways, living out of doors and allowing the forces
of health to purify the body.

313. Effects of Bacteria. — You learned that they produce
decay in unsound tissue. They destroy the albumin in
which they grow, producing foul-smelling gases and a
number of poisons called ptomaines, if formed after death.
Ptomaines cause most of the symptoms produced by eating
decayed meat. A special kind of ptomaine sometimes
forms in milk and ice cream which has been kept for a long
while. This is why ice cream which has been melted, and
frozen a second time, is dangerous.

314. The growth of bacteria in an unsound, living
body, produces poisons called toxins, which, circulating
among the sound tissues, produce weakness and disease.
Disease germs may grow upon the injured cells in an
open wound, causing offensive matter to form. In severe
cases they 'cause swelling of the surrounding parts, with
erysipelas or blood poisoning. Diphtheria, typhoid fever,
consumption, cholera, lockjaw and la grippe are all
diseases in which germs have been proved to be present.

1 82 ELEMENTS OF PHYSIOLOGY

Typhoid fever, for instance, is usually contracted through
the use of water from an impure source. There have
been cases of a spring or well becoming infected with the
typhoid germs and giving typhoid fever to the unhealthy
members of every family that used water from it. It
reqtdres many bacteria to produce infection ; to cause some
diseases several millions are necessary. Certain kinds of
communicable diseases can be caught only by coming in
contact with the sick person, or with some article that he
has touched, or by going into the room where he is sick.
These diseases are said to be contagious, since they are
caught by actual contact. Diseases that are transmitted
through the air, contact being unnecessary, are said to be
infectious. Measles, scarlet fever, mumps, whooping cough,
and smallpox are contagious diseases, and germs are sup-
posed to be necessary for their existence, but no germ has
ever been found.

315. It has never been proved that germs will cause
harm or disease to a perfectly healthy body. The germs
that produce boils enter the skin at some scratch or break
that reaches the lymph spaces. But a person with pure
blood and lymph could have a number of breaks in the
skin and would probably not have a single boil. Some
germs seem to change their nature or the nature of the
toxins they form, according to the material upon which
they live. Many germs seem to be harmless when living
in certain conditions, but, if they find a diseased condition,
they seem to change their nature and begin the forma-
tion of poisonous toxins. This is known to be true of the
colon bacillus and other germs.

316. How Bacteria are destroyed within the Body. — The
body of one who is worthy of physical health has three
very efficient means of defense :

First. — The white blood cells have it for their chief
function to seek out bacteria and to devour and destroy them

HYGIENE OF RESPIRATION 183

(Fig. 156). This explains why so many germs are neces-
sary to transmit a disease.

Second. —The plasma of the blood and lymph, and even
mucus, are able in some unknown way to destroy germs of
disease.

Third. — The serum of the blood often develops a sub-
stance called an antitoxin,
which poisons the germs
and stops their action.
When the disease has pro-
gressed for a time, the anti-
toxin is formed in sufficient
quantities to kill the germs
and the disease is cured.

a, germ destroyed by white blood cell; o, cell
317. Malarial fever arises destroyed by germs and the germs multiply-

f rom the presence of a one- ing' using the ceU for food
celled animal similar to the ameba, that lives through one
phase of its existence in the body of a certain kind of
mosquito (Fig. 157), and reaches the human system by the
mosquito's bite. It then multiplies and destroys the red
corpuscles, causing the pale skin of a person suffering
from malarial fever. It has not been proved that
malarial fever comes in no other way. It may be possible
that this fever is caused by the vapors that arise from
marshy places. It increases in any region where the trees
are felled, as their destruction interferes with the drainage,
and thus gives rise to ponds and marshy places where
mosquitoes breed. The wiggle-tail takes about ten days to
become a mosquito. If kerosene is poured upon the water
at shorter intervals than ten days, no mosquitoes will hatch.
Tin cans, barrels, and hollow stumps containing water,
furnish breeding places for mosquitoes (Fig. 157).

318. The negroes in the Southern states seem to have
developed in the blood an antitoxin, which enables them to
live in " bottom lands " along rivers. In Africa they do

1 84

ELEMENTS OF PHYSIOLOGY

not often have the jungle fever, so fatal to Europeans who
have not become "acclimated" — that is, whose blood has

FIG. 157. — Mosquitoes. Comparison of —

The Non-malarial Genus Culex.
Palpi short.
Wings not spotted.
Legs sometimes spotted.
Position at rest, parallel to surface.

Larva, or wiggle-tail, breathes, and rests
perpendicular to surface of water.

The Malarial Genus Anopheles.

Palpi long.

Wings sometimes spotted.

Legs not spotted.

Position at rest with abdomen and hind
legs elevated at an angle to surface.

Larva, or wiggle-tail, is parallel to sur-
face of water when it breathes.

The sucking tube and feelers are long in both genera. The long palpi of the malarial genus
furnish an infallible sign. The palpi are found on each side of the sucking tube. The
feelers are next to the palpi.

not developed the antitoxin which kills the germs caus-
ing jungle fever. It has been shown that the mosquito
is probably instrumental in transmitting yellow fever.

319. Antitoxin Treatment. — If the toxins from diph-
theria germs, grown in suitable material, are injected into

HYGIENE OF RESPIRATION

185

the veins of a horse, the horse's blood will soon develop
the antitoxin of the disease. If the blood is drawn and
allowed to clot, clear serum may be separated. If this is
injected into a person suffering
from diphtheria, it tends to destroy
the germs and stop the disease.
It may prevent disease in the case
of a person who has been exposed
but in whom the disease has not
yet developed. The antitoxin treat-
ment has been tried without success
in several other diseases. Germs
may be transmitted by drinking-
water, in the food, Or through the FIG. 158. — How to have a Dry

air. Cellar-

320. Vaccination. — In 1776 E. «'dam^ro<

Jenner of Berkeley, England, learned that the milkmaids
of the shire considered accidental cowpox, caught while
milking, a sure preventive of smallpox. Twenty years
later he began to vaccinate with cowpox
material to prevent smallpox. Vaccina-
tion protects only for a few years. If
exposed to smallpox, one should be vac-
cinated, unless he has been vaccinated
within the last few years. Arm to arm
FIG. 159. — A " Trap " vaccination is dangerous. Only fresh virus
of Water to Prevent from healthy cows should be used. If the

Gases from coming ,, , ,.

into Houses through arm becomes very much swollen and dis-
Drainage and abled, it is a sign that the blood has been

Sewer Pipes.

poisoned by the use of impure material.

321. Why a Person can have Some Diseases only once. —

Why does not one have measles, smallpox, and some other
germ diseases a second time ? It is believed to be on the
same principle that vaccination prevents smallpox the first
time. After once having a disease, the antitoxin of that

1 86

ELEMENTS OF PHYSIOLOGY

disease, or the power of the blood to develop it, remains
and affords protection from the bacteria.

322. Destruction of Bacteria outside of the Body. — The
sun is the great destroyer of bacteria in summer and in
tropical climates. Cold destroys them in winter and in
cold climates. Sternberg has shown that exposure to one
hour of sunshine destroys the bacillus of consumption.
Wind drives away bacteria. It is almost impossible to
transmit disease in the open air. Some germs feed upon

FIG. 160. — Poorly Drained and Un

healthful Site for House.

a, sand; £, clay.

FIG. 161.— Healthful House.
a, sand; b, rock.

other germs. In the soil are certain kinds of germs which
oxidize all organic matter, including other kinds of germs.
Thus germs can filter through only a few feet of sand
before they are destroyed. Well water is safe to drink in
the country, if no impurities reach the soil near the well,
but in towns where the ground becomes soaked with germ-
laden sewage, impurities penetrate farther and well water
is unsafe (Figs. 162, 163).

323.. Cleaning with soap and water removes germs. Dry-
ing kills many germs, but some species are harder to kill
when dry ; in that condition they will stand even freezing.
Heat, equal to that of boiling water, applied for 15 min-
utes, will kill almost every kind of germs. It does no
harm to leave air in the top of canned vegetables and jars
of preserves, but if they are to keep fresh, the germs must
be killed by a boiling temperature. Milk is a nourishing

HYGIENE OF RESPIRATION

I87

soil for germs which cause stomach trouble with bottle-
fed babies, unless the milk and the bottles are subjected to
hes t. Such milk is said to be sterilized.

324. Many chemicals, as carbolic acid (if applied directly
to the germs), bichlorid
of mercury (i part to
1000 parts of water), ^.
chlorid of lime, destroy
germs and are called
germicides (" germ-kill-
ers "), and antiseptics
(against decay). They
are called also disinfect-

ants, and are applied

to houses, clothes, and

premises where disease

germs are supposed to

lurk. The room and bedding where there has been an

infectious disease should be thoroughly disinfected. Any-

FIG. 162. — Badly Made Well polluted with
Sewage.

thing without germs, as pure food, is said to be aseptic

(without decay).

325. Aseptic Surgery.
— Some years ago, when-
ever a leg was amputated,
or other surgical opera-
tions were performed,
there was the great dread
that mortification would
set in. It caused death
in one third of the sur-
gical cases. Now, with
aseptic surgery, mortification and blood poisoning are
very rare. The surgeon washes and sterilizes his hands
and instruments and his aprons. He scrubs the field of
operation on the body just as he does his hands., The

FIG. 163. — Inappropriate Neighbors.

1 88 ELEMENTS OF PHYSIOLOGY

safety which has been brought about by aseptic surgery
depends upon excluding the germs of disease.

326. Alkaloids. — There is another class of organic
poisons, closely related to ptomaines, which should be
mentioned. They are vegetable and animal alkaloids.
Ptomaines are formed by bacteria in dead organic matter ;
toxins are formed by bacteria in living bodies. The alka-
loids are formed without bacteria, but are waste products
formed in living animals and plants by their life processes.
Among vegetable alkaloids may be mentioned strychnine
of nux vomica, daturine of the jimson weed, atropine of
the belladonna, nicotine of tobacco, podophyllin of the may-
apple root, caffeine of the coffee plant, quinine of the
Peruvian bark or cinchona tree, theobromine of coca, theine
of tea, morphine of the poppy, etc. They form the active
principles of most medicines, and are given for either a
narcotic (deadening) or a stimulating (exciting) effect.

327. The dangerous properties of most medicines cause
us to wonder why some people experiment with them so
rashly without professional advice. Persons who would
not think of playing the part of a lawyer, or a theologian,
or even of trying to doctor a horse, if the horse was of
much value, do not hesitate to prescribe the most virulent
remedies for their friends and families. The course in
medical schools in the United States is now usually four
years in length. Most of our physicians are not mere pill-
peddlers and prescribers of drugs, but are capable of
advising their patients in every aspect of their physical
welfare, and their advice should be taken and paid for as
readily as their drugs.

328. Taken in large doses, alkaloids are virulent poisons.
The chief animal alkaloids are xanthin, and other com-
pounds related to uric acid. Very little is known about the
alkaloids and their properties.

329. A Curious Theory. — There is an artless theory com-

HYGIENE OF RESPIRATION 189

mon among unlettered people which holds that disease
is a distinct thing, and that when God made the various
diseases, he made plants to grow, each of which contains
the infallible remedy for one of the diseases. Such per-
sons when they are ill, and after various treatments remain
ill, cherish the firm conviction that if they could only find
the .right remedy that is growing in some plant, somewhere
in the world, they would, immediately be cured, without
any attention to hygiene and the conditions necessary to
health and its recovery. Patent medicine venders particu-
larly foster this idea, although each one illogically adds
that his medicine will cure all diseases indiscriminately.
They give instances of the cat and dog that get sick and
cease eating meat for a time and are said to eat grass.

330. This simple theory is opposed to all the facts.
The poisons in plants are waste products that the plant
seeks to remove. They are therefore found mostly in the
parts of the plant that will be shed, as the leaves, seeds,
and bark. The poisons serve meanwhile to protect the
plant from animals. The only animals (besides man) that
will touch the tobacco plant are the goat and the tobacco
worm; their bodies seem to have become used to the
poison. No sick cat eats nightshade, no sick cow eats
jimson weed. The very bitter or repulsive taste of most
poisons show them to be unsuited to the animal body.
No child would drink a liquid containing the bitter alkaloid
caffeine, unless it were influenced by the example of its
elders, and the bitter taste were disguised with milk and
sugar.

APPLIED PHYSIOLOGY
EXERCISE I

i. State how in the case of a person of poor figure, a gradual re-
molding of the cartilages (which ones ?), the strengthening of the
muscles (which ones ?), and the practice of deep breathing may each
contribute toward acquiring a correct and perfect figure.

190 ELEMENTS OF PHYSIOLOGY

2. How far is it in one's power to determine the shape and appear-
ance of his own body ?

3. Which is most disagreeable, a smoky fireplace, a smoky stove,
or a smoky man ?

4. Give reasons why the weight of our clothing should hang from
the shoulders and not from the waist.

5. Should a hat be well ventilated ? (A punch for making the
holes costs a dime.)

6. Name habits that impair the power of the lungs.

7. Which part of ordinary breathing uses no will power, although
none of the respiratory muscles are involuntary ?

8. How could you convince a person that a bedroom should be open
while and after it is swept ? That it should be ventilated at night ?

"9. Why do some persons " get out of breath " readily after a meal ?

10. Can a person become so used to bad air that he will not notice
it ? That it will not injure him ?

EXERCISE II

11. Which is the more offensive, the tobacco chewer, who chiefly
pollutes the ground, or the smoker, who pollutes the air ?

1 2. Why are those who have pimples on the face likely to multiply
their number by picking and squeezing them with the fingers ?

13. Give the advantages of slow, deep breathing as compared with
quick, shallow breathing.

14. Why do those who stand up to hoe not get tired half so quickly
as those who bend or " hump " over ?

15. Why do students who sit in rocking-chairs, or from other causes,
lean the head forward when they study, often find that they recover
from drowsiness if they sit erect ?

1 6. How are high collars a fruitful source of bad colds ?

17. Is ventilation easier in winter or in summer ?

1 8. How do you account for the fact that people of general intelli-
gence on most subjects sometimes use oil stoves, which are stoves
without stovepipes ?

19. If the draught up the chimney of the fireplace, when the fire is
burning, takes up a volume of air sufficient for many people, why is it
unwise to open a window ?

NOTES

i. Respiration in Consumption. — Doctors Robin and Binet studied
the respiration of nearly 400 cases of consumption, and reported their

HYGIENE OF RESPIRATION 1 91

results to the Paris Academy of Sciences (1901). They discovered
that the respiratory changes become greater in consumptive patients
than in healthy persons, thus completely overturning the general belief
on the subject. The volume of inspired air was nearly doubled.

The investigators therefore believe that the old name "consumption"
is a good name for the disease. To cure the disease, it is not sufficient
to remove the bacillus. The labored and exhausting breathing due to
abnormal functional and nutritive trouble brings the lungs into a con-
dition favorable to the development of the bacillus, and these troubles
must first be removed.

2. The Cure of Consumption. — D. M. Appel, major and surgeon,
United States Army, makes the following statement : —

" We have demonstrated at the Fort Bayard sanitarium for soldiers
that we can cure consumption in any stage. I don't mean to say that
if people come to us with lungs so far gone as to destroy their breathing
power we can cure them, but I do say we can cure what has long been
regarded as hopeless — the third stage of the disease. The treatment
is merely that which has been for years followed by the practitioners of
the rational system. It consists of open-air living, generous diet, and
rest. During the daytime the patients are not allowed under cover, and
at night all windows are wide open. It is a common thing for these
patients to gain ten pounds a week. One increased from 140 to 190,
another from 128 to 210, and another from less than 100 to 160."

3. "The degree of vital activity of which we are capable is gauged
exactly by the amount of oxygen we breathe. The bird which soars
above the clouds has enormous lungs ; even its hollow bones are util-
ized for breathing purposes ; it may almost be said that a bird breathes
to the very tips of its toes. The frog, on the other hand, has no chest,
has merely a small breathing bag, which it fills at comparatively long
intervals. Compare the activity of the swallow, easily keeping pace
with the lightning express, with that of the frog, croaking amid the
slime and miasma of a stagnant pool" (J. H. Kellogg, M.D.).

4. "The Greeks, whose figures remain everlasting and unapproachable
models of human beauty, wore no stays. The first stays mentioned
that I have ever found, is in the letters of Synesius, Bishop of Cyrene,
on the Greek coast of Africa, 400 A.D. He tells how, when he was
shipwrecked on a remote part of the coast, and he and the rest of the
passengers were starving on cockles and limpets, there was among them
a slave girl, out of the far East, who had a pinched, wasp waist, such as
you may see on the old Hindu sculptures and such as you may see on
any street in any British town. 'And when the Greek ladies of the
neighborhood found her out, they sent for her from house to house to

IQ2 ELEMENTS OF PHYSIOLOGY

behold, with astonishment and laughter, this prodigious waist, with
which it seemed to them impossible for a human being to breathe,
or live ! '

" In future years, when mankind has learned to obey more strictly those
laws of nature and science, which are the laws of God, the present
fashion of tight lacing will be looked back upon as a contemptible and
barbarous superstition, denoting a very low level of civilization in the
people who have practiced it" (Rev. Charles Kingsley).

CHAPTER XII
FOOD

331. Proteids, or Albuminoids. — It was learned in an
early chapter that protoplasm, the basic life substance,
is not always the same in composition, but there is one
material that is always found in it and is the test by which
it is known to be protoplasm, and that is albuminous
material. It was learned in Chapter II that albumin
always contains nitrogen, the most inert and inactive of the
elements, and that albumin gives strength and stability to
the cells and tissues. The fibers of connective tissue, for
instance, are albumin. It is the great tissue-building
material, and as the activities of cell life are constantly
using up the materials of the cells, we are not surprised
that albuminous or nitrogenous food is reckoned as the
most essential of all foods for sustaining animal life.
Albuminous foods are commonly called pro'te-ids, or pro-
te-in foods (Greek protos, first or most important).

332. Carbohydrates, or Sugars and Starches. — Why are
roasting-ears sweet, although mature corn is not? It is
because the sugar in the first has been changed to starch
in the second. On the other hand, ripe apples are sweet
because the starch of green apples has been changed to
sugar. Starch and sugar are so nearly alike in composi-
tion and change so readily into each other, that as foods
they are classed together. It was learned in Chapter IX
that the sugar in the blood -is diminished by muscular
exertion. The oxidation of the sugar is accompanied also

o 193

194 ELEMENTS OF PHYSIOLOGY

by increase of the bodily heat. It was learned that fat
is stored up in the interior of cells (Fig. 38). Sugar can
be changed into fat by the cells and stored away for future
use in producing heat and motion. Thus sugars and
starches, or the carbohydrate class of foods, have three uses.
Knowing the great importance of movement to our life,
and also the fact that the body is constantly losing heat,
day and night, winter and summer, the importance of this
class of foods is easily understood. Some animals and
plants have fat and oils or liquid fat in their tissues .ready
for use as food by man. This gives us a third class
of foods, the —

333. Fats. — Fats are exactly the same in function as
the carbohydrates. A pound of fat in oxidizing gives
out two and one half times as much heat as a pound
of sugar or starch, and about the same as a pound of
albumin. It may be stored up as fat in the body if not
oxidized in the muscles to promote heat and work. Under
all circumstances, a certain amount of nitrogenous or
proteid food is required by the muscular tissue, for, as
in all cells, the real living framework of the muscular
fibers contains albuminous substances as one of its essen-
tial constituents. We may, then, think of fat and sugar
as having the same relation to the structural substance
of the muscle as the coal has to the structural parts of
the engine.

334. Mineral Foods. — The food stuffs so far mentioned
are all organic substances. There are many inorganic or
mineral food stuffs, such as carbonate of lime, phosphate
of lime, iron, and sulphur that are necessary to the body,
yet we cannot get them directly from mineral sources.
The bones are largely made of lime, and if we could
assimilate lime by eating it, or drinking it in " hard " water,
then the people who live in limestone regions and drink
hard water might all be giants. We can get phosphates

FOOD 195

and carbonates of lime from wheat and other grains ;
sulphur is contained in eggs ; iron is contained in grains,
tomatoes, and most vegetables. Iron tonics, tincture of
iron, etc., do not contain iron in an organic form. Only
plants can furnish these mineral foods in a form most
suitable for assimilation by our bodies. Animals must
get them from vegetables, and they may become part of
the bodies of several successive animals as one makes food
of another.

335. But you may ask, how is it that plants only have
the power of nourishing themselves with mineral sub-
stances although we take water and common salt as food?
Are these two exceptions to the rule ? It is doubtful whether
such substances can be strictly called foods, for food must
undergo a chemical change in the body, while water and
salt do not, but are found to leave the body unchanged
in the perspiration and other excretions. They serve only
a mechanical purpose of dissolving the true foods and
bringing them within the reach of the cells, for it was
learned that all the cells lead a watery existence. Nerve
cells, as well as others, are bathed in lymph, and it is in
a manner true that we even think under water. The
mechanical foods, are therefore of the greatest importance in
keeping the tissues in the right condition for the cells to
work.

336. Table: —

FOOD STUFFS

f Proteids — Nitrogenous substances.
Organic \ Fats and oils 1 Non-nitrogenous

[ Sugars and starches J substances.

\. Inorganic !Waten

I Salts (salines).

The non-nitrogenous foods are sometimes called carbo-
naceous foods because they contain a greater amount of
carbon than the proteids ; remember, however, that the
proteids have some carbon.

196 ELEMENTS OF PHYSIOLOGY

337. Composition of Foods. — Very few of the articles of
food we eat consist of only one of the classes of foodstuffs
mentioned ; most foods consist of several foodstuffs com-
bined. Oatmeal, for instance, contains starch, a small pro-
portion of oil, a large proportion of proteid, some mineral
salts, and water. Let us see how the four classes are
represented in milk. The part that makes it liquid is
water, the sweetness comes from the sugar, the cream rises
as oil, and the curd will furnish cheese, which contains
casein, a form of proteid.

338. Experimental Tests of Starch and Proteid. — With
ten cents' worth of iodine from the drug store the teacher
may try the following experiments : — Dilute a part of the
iodine with water to a light brown color. Make a thin paste
by boiling laundry starch in water. Put some of this paste
into an ordinary glass and pour a little of the dilute iodine
upon it. Notice that the starch turns instantly to a beau-
tiful blue color. This is one of the chemical tests for
starch, and is called the iodine test.

339. Put a little piece of lean meat into some of the un-
diluted iodine ; the meat turns brown. This is the iodine
test for proteid.

340. Soak some grains of corn, wheat, rye, and other
grains for a few hours. Make thin slices across each
kernel. Place a slice of each grain in a few drops of
dilute iodine in a saucer, and notice which part turns blue.
Put slices of each grain into strong iodine, and after they
have been acted on for several minutes, rinse off the
iodine. Notice which part is blue and which parts are
brown. In the grain of corn, for instance, the white part
of the kernel turns blue, showing the presence of starch,
while the germ and the part around it turn brown, show-
ing the presence of proteid. The oil in the corn is mixed
with the starch and proteid, and cannot be shown by
a simple experiment. If the grain of corn is burned, a

FOOD 197

small amount of ashes remains, showing the mineral
matter. Cereals contain all of the four classes of food.

341. Sources of Food. — All parts of a plant may furnish
food: the seed, as the various grains, nuts, and fruits ; leaves,
as lettuce, cabbage, dandelion; roots and tubers, as pota-
toes, beets, turnips, tapioca (root of cassava) ; stem, as sago
(pith of sago palm) ; saps, as sugars (of cane, beets, and
maple tree); honey; and oils (from peanuts, cottonseed,
olives, pecans and other nuts).

342. Sources of proteid : albumen, in white of egg ;
gluten, the sticky or gluey part of grain ; casein, in cheese
and the curd of milk; fibrin, in the blood of animals;
myosin, the basis of lean meat ; gelatin, obtained from
bones and ligaments by boiling ; vegetable casein, in beans,
peas, and nuts.

343. Sources of fats and oils : cream of milk, yolk of
egg, oil of nuts, olives, cottonseed, cocoanut, and fat of
meat.

344. Sources of starch : corn, wheat, rice, oats, and other
grains, potatoes, cassava, arrowroot, sago (in this country
the last two are usually potato starch sold under those
names), beans, peas.

345. Sources of sugar : sugar cane, sorghum, dates,
honey (almost pure sugar), bananas (20 per cent), grapes,
fruits, beets, maple trees.

346. Study the table showing composition of foods
(§ 434). Which grain has the least proteid ? Which has
the most ? the most starch ? the least ? the most fat ? the
least ? What vegetable foods are rich in proteid ? In oil ?
Which food has least nutrition (contains most water and
cellulose) ? Which has most nutrition ?

347. Experience has shown that the diet best suited for
the body must contain, besides water, one part of nitrog-
enous food to four parts of non-nitrogenous food. Which
of the foods in the table approximate this proportion ?

IQ8 ELEMENTS OF PHYSIOLOGY

348. Outline of Digestion. — The food is made soluble in
the alimentary canal and is absorbed by the blood vessels
and lymphatics in its walls. This canal is about thirty feet
long (Plate III) and consists of —

(1) The mouth, where the food remains about a minute,
while it is chewed and mixed with the saliva ; the saliva
changes a portion of the starch to malt sugar.

(2) The gullet, a tube nine inches long, running from
mouth to stomach and lying just in front of the vertebral
column.

(3) The stomach, a large pouch where the food is stored
and from which it passes in the course of several hours,
having become semi-liquid, and the proteids having been
partly digested by the gastric juice, an acid secretion from
small glands in the stomach walls.

(4) The small intestine, a narrow tube more than twenty
feet long, where the fats are acted upon for the first time,
and where the starches and proteids are also acted upon, and
where, after about ten hours, the digestion and absorption of
the three classes of foods is completed (Figs. 175, 177).

(5) The large intestine, about five feet long, where the
last remnant of nutriment is absorbed and the indigestible
materials in the food are gathered together (Plate IV).

349. Water and salt require no digestion preliminary to
absorption. After the food is digested and absorbed and
carried to the tissues by the blood and lymphatics, it must
be assimilated, or made into material similar to the contents
of the cells, and stored up for future use. Drugs, narcotics,
and alcohol are not stored up in the cells, but, it is believed,
are largely oxidized in the blood and lymph, or expelled
from the system unchanged.

350. The Waste of the Body. — When the foods are oxi-
dized in the body, there are several products of oxidation
called waste products. The starches and sugar, fats and
oils, when oxidized, give rise to water and carbon dioxid.

FOOD 199

The proteids give rise to urea. This is excreted by the kid-
neys, and when it is separated from the kidney secretion by
chemical means, it appears as a white, crystalline powder.
There are also found in the secretion of the kidneys small
quantities of phosphate and sulphate of lime, sodium, and
potassium. Urea is a substance of great importance, as it
is the chief waste substance produced by the process of
decay and growth in the cells of the body. Carbon dioxid
leaves the body through the lungs, and water leaves it
through the lungs, kidneys, and skin.

351. How the Waste is measured. — If a man were to
live all day in a small chamber placed upon very deli-
cate platform scales, he would find that he lost weight
every second of his existence except when taking food,
and more rapidly at some times than at others, the amount
of loss depending upon the activity of his body. The
loss of weight occurs through the excretions which the
man gives off. At average temperature of the air and
average activity of his body, the day's loss to be replaced
by food eaten, water drunk, and air breathed, would be
about as follows : —

From the large intestine . 5 oz. excrement.

From the skin 25 oz. perspiration.

From the kidneys ... 50 oz. excretion.

From the lungs . . . . 35 oz. carbon dioxid and water.

Total . . . . 115 oz.

The total loss is, then, nearly 8 pounds, three fourths of
which is water (nearly 6 pounds). The remainder, except
the 5 ounces of excrement, consists of those waste materials
(solid or gaseous) which result from the breaking down of
the active living protoplasm into simple chemical sub-
stances, through the process of oxidation. This amounts to
2J\ ounces and is apportioned as follows : perspiration, \
ounce of salts, and a trace of urea ; the kidney secretion,

200 ELEMENTS OF PHYSIOLOGY

I ounce of salts and \\ ounces of urea; the lungs, 25
ounces of carbon dioxid gas.

352. Variation in the Amount of Food. — Suppose the
man in the little room on the scales were to work, — for in-
stance, turn a hand mill or swing dumb-bells, — would the
amount of waste be increased? Would the increase 'be
chiefly urea (from proteid) or carbon dioxid (from carbo-
naceous food)? If it were to turn very cold, the loss of
heat from his body would be greatly increased, and the
waste correspondingly increased. If he were to think
very hard, the increase would be marked. If he were to
remain perfectly quiet in body and calm in mind, the waste
would be decreased ; likewise, if the temperature became
mild. The effect upon the waste would not always be
perceptible until some hours after its cause, for it takes
time for the circulation and organs of excretion to remove
the waste after the material of the waste has been formed.

353. The Most Important Class of foods is the proteids.
They are substances consisting of nitrogen, carbon, hy-
drogen, oxygen, sulphur, and phosphorus. As sugar and
starches, fats and oils, contain no nitrogen, the tissues can-
not be built from them alone. Proteids not only build
tissue, but are a source of some heat and energy, so life
could be sustained on this class of foods alone; but it
would not be the best and healthiest way of living, because
in order to get enough carbon, there would be taken in an
excess of nitrogen, and the digestive organs would be
given extra work which would be of no value to the body.

354. Proportions of Nitrogenous and Carbonaceous Food
needed. — The carbon dioxid gas which is daily lost by the
body contains 8 ounces of carbon, while the urea which is
lost contains a little more than \ ounce of nitrogen. The
body thus loses carbon and nitrogen in the ratio of
about i to 15. The food, of course, must supply these
elements in the same proportion. If one foodstuff be

FOOD 2O I

taken in excess, part of it will be wasted. If the amount
of one foodstuff absorbed be too little, the man must con-
sume part of his body substances, and will lose in weight.
In pure albumin, such as the white of egg, the proportion of
nitrogen to carbon is I to 3 J. Since the proportion needed
in his body is I to 15, if he eats enough white of egg to
get just enough nitrogen, he would only get about one
fourth as much carbon as he requires ; for the body needs
15 times as much carbon as nitrogen instead of 3| times as
much. But if he were to eat enough of egg white to get
the carbon required, he would eat four times as much
nitrogen as the body would use. If he subsisted on lean
meat, he would eat four pounds a day to gain sufficient car-
bon, while three fourths of a pound would have supplied
sufficient nitrogen.

355. A dog could readily live on lean meat alone. If a
man attempted to do so, the kidneys would have to excrete
the larger part of the nitrogen unused, and would probably
become diseased from overwork, if, indeed, the meat did
not become nauseous to the palate and stop the experi-
ment. Yet, so flexible is the human system, if only
plenty of fresh air and exercise are taken, that the
Gauchos (a tribe of Indians on the Pampas of South
America) live upon dried beef alone. But the habit is a
strain upon the organs, and must have been acquired
gradually. They are a very short-lived tribe.

356. Proteid contains carbon as well as the carbona-
ceous foods, but not so much ; and it is found that proteid
and carbonaceous food in the proportion of I to 4 gives
the needed proportion of nitrogen to carbon (i to 15).

357. How the Proportion of One to Four is attained. -
Since fat, starch, and sugar do not contain nitrogen, it is
impossible to live upon them alone. A dog fed only upon
carbonaceous food, died in a few days. Since these foods
contain plenty of carbon, it is obvious that by mixing them

202 ELEMENTS OF PHYSIOLOGY

with proteid, the required proportion of nitrogen to carbon
can be attained. In about two pounds of bread there is
enough carbon for the day's needs, but it gives only half
enough nitrogen. So, by combining lean meat, cheese,
beans, or nuts with bread, a sufficiency of both elements is
obtained without unnecessary work or waste. With the
addition of plenty of water and a little salt, the diet is
chemically complete.

358. How Different Peoples attain the Proportion. — Milk
has an excess of nitrogen, and oatmeal an excess of car-
bon ; oatmeal and milk form a perfect food, and it is not
surprising that a whole race (the Scotch) have lived upon
it and thrived. Potatoes are mostly starch and water ; the
starch in them is more than four times as much as the pro-
teid, and an Irishman who tried to live on potatoes alone,
would have to eat seven pounds a day to get enough proteid.
By eating milk and eggs also, he can get along on half the
amount of potatoes named above, and every Irish peasant
is said to keep a cow and chickens. The Mexicans eat
bread made of corn meal, and supply the proteid by using
beans as a constant article of diet. The Zulus live on
cracked corn by adding milk to it. The Arabs live on
barley and camels' milk, rarely eating the camels' flesh.
Hundreds of millions of people in Asia (the Hindoos, Chi-
nese, and others) subsist mainly on rice, which is more
nearly pure starch than any of the grains, containing only
6 per cent of proteid, about half as much as wheat and
corn ; the chief addition they make is butter or other fat,
and beans, which contain vegetable proteid. Their meagre
diet may partly account for their lack of energy and brav-
ery, and the ease with which they are conquered and con-
trolled by European nations. The greatness of a people is
largely dependent upon their diet.

359. The Body's Method of regulating the Food. — We
should not think that the food eaten must be regulated

FOOD 2O3

with the greatest precision. Any reasonable excess will
either pass through the canal unabsorbed, or be excreted
from the blood, without great injury to the body. A want
of any of the necessary elements will be well tolerated for
a time until a craving for a certain kind of food will lead
later to the supply of the elements needed. If a person
feels bad, or the digestion seems weak, some will advise
dieting. There is a tendency among certain writers on
hygiene to overrate the importance of this subject. If
the laws of health in regard to fresh air, muscular
exercise, sleep, cleanliness, temperature, and the use of
stimulants be observed, our appetites will be a suffi-
cient guide in the matter of diet. These matters should
first be looked to, and dieting then will probably become
unnecessary.

360. It is an instructive and important fact, that too
much consciousness of what is eaten and too much dwell-
ing on what might be the consequence of eating this food
or that food, will bring about serious derangement of the
digestion. If we do not abuse our tastes, but give the
proper heed to them, we may keep a delicate indicator
which will, in a more perfect way than any scientific table
has yet done, tell us what is needed.

In this Chapter alcohol and other narcotics have not
been mentioned as they are not to be classed as true foods.
Professor Atwater recently found proof of what has
always been believed by physiologists, namely ; that alcohol
is oxidized in the body and that it may to a slight extent for
a few days take the place of carbohydrates. Yet alcohol
causes the lining of the stomach to become unnaturally
congested, and habitual drinking causes it to become
inflamed and even ulcerated. A true food must be capable
of nourishing the body without injuring it.

CHAPTER XIII

THE DIGESTION

361. The Digestive System. — The food, in order to be
of service to the body, must undergo several changes.
Its nutritious portion must be separated from the innutri-
tious ; and the former must be made soluble, or in fit
condition to be taken up by the blood and carried to the
tissues. This process is called digestion, and the assem-
blage of organs by which it is carried on is called the
digestive system. The tube which forms the receptacle
for the food during digestion is called the alimentary
canal. In the carnivora, or flesh-eating animals, whose
food contains but a small amount of indigestible matter,
the alimentary canal is comparatively short, being, when
stretched out, only three or four times the length of the
body. In the herbivora, or grass-eating animals, the
canal is thirty times the length of the body. In the hog,
which is omnivorous ("all-eating"), it is ten times the
length of the body. If man's trunk only is counted, the
canal is twelve times as long; if his height is counted,
the canal is six times as long.

362. The Alimentary Canal has three coats in its walls
throughout its whole length. What is each for? The
inner coat, or lining, is a delicate epithelial tissue called
the mucous membrane. It forms a smooth lining to
prevent friction, and secretes a mucus which serves the
same purpose. The next coat is the submucous coat ; it
is of elastic connective tissue, and serves to toughen
and strengthen the wall, and to bind the mucous coat to

204

THE DIGESTION 2O$

the muscular coat. Outside of this is the third coat. It
is composed of several layers of involuntary muscular
tissue, which, by its contraction, causes the food to move
along the canal (Fig. 169).

363. In the walls of the alimentary canal are numerous
blood vessels and lymphatics? Opening on its inner sur-
face are mouths of ducts from the various glands of the
digestive system. Some of the glands are of considerable
size and lie outside of the canal ; others are very minute
and are embedded in the walls of the canal ; their secre-
tions render the food soluble.

364. The Real Inside of the Body. — When we swallow
food or drink, we are accustomed to say that it is in the
body, but anatomically and physiologically this is not
correct. It is on the outside anatomically, because the
mucous membrane is continuous with the skin, which is
the external covering. It is on the outside physiologically,
because the food must pass through the mucous mem-
brane before it can be assimilated by the tissues and
become of use to the body. In many kinds of sickness
the secretion of the digestive fluids diminishes or ceases
altogether, and persons sometimes make a sad mistake in
thinking they are giving food to the patient, when the
food is only irritating the alimentary canal and ferment-
ing or decomposing, and never really getting inside of the
body. A lean person often eats a great deal, expecting
to get fat, and finds that although he has swallowed the
food, the nourishment has never really entered his body.
Many a dyspeptic is tortured with the gnawings of hunger
yet is continually eating, and is hungry still, because he
does not really get the food.

365. The Mouth. — The food is held in the mouth for
a short time while it is mixed with the watery alkaline
fluid called the saliva, and is ground up fine by the teeth.
The partition between the nose and the mouth is formed

206 ELEMENTS OF PHYSIOLOGY

by the palate bones, covered with mucous membrane.
The larger part of the roof of the mouth is formed by
these bones and is called the hard palate. The roof is
completed in the rear by the fleshy soft palate. The floor
of the mouth is occupied mostly by the tongue ; the lips
form the front wall, and the "cheeks the side walls. The
cheek is composed partly of a large flat muscle called
the buccinator ("trumpeter," because used in blowing a
trumpet). The contraction of the trumpeter muscles, to-
gether with the movements of that flat muscle called the
tongue, keeps the food between the teeth in the act of
chewing, or mastication.

366. Salivary Glands. — There are three pairs of glands
that secrete saliva. In structure one of these glands with
its duct resembles a minute bunch of grapes with a hollow
stem. The largest, called the parotid, is just beneath the
skin in front of the ear. Its duct opens into the mouth
in the upper jaw opposite the second molar tooth. This
gland swells in a disease called the mumps. The next
largest gland is the submaxillary ', lying within the angle
of the lower jaw. Its duct opens into the floor of the
mouth. The smallest, the sublingual, lies farther to the
front ; both glands of the pair lie beneath the tongue, and
open by a number of ducts. The fluid produced by these
glands becomes mixed with the mucus from the mucous
membrane of the mouth and is called the saliva.

367. Saliva. — This is a thin, colorless, alkaline liquid,
slightly sticky, and often containing air bubbles. About
TTMnf Part °f the saliva is a white substance called ptyalin,
which has the power to change starch to malt sugar while
remaining unchanged itself. Hence ptyalin is a ferment.
Ferment is the name given to certain organic substances
which act chemically upon other substances, and change
their nature without becoming changed themselves. From
one to three pints of saliva are produced daily. Its flow

THE DIGESTION

207

is excited by the act of chewing and by anything held
in the mouth, especially if it be of an agreeable taste or
odor. Hunger, or the sight or thought of agreeable food,
makes the mouth water by stimulating the cells in the
glands to activity by means of the nerves. But by far
the most powerful of all the excitants to the salivary flow
is dryness of the food. Only one fourth as much saliva is
deposited in the same length of time when eating oatmeal
and milk as when eating crackers or dry toast (Fig. 164).

B

FIG. 164. — Cells of the Salivary Gland.

At after rest; B, after a short period of activity; C, after a prolonged period of activity.
Shriveling and loss of granules occur.

I. Absorption, or the passage of digested food into the
blood vessels, is an important sequel of the digestive pro-
cess. A little of the water containing sugar and salts is ab-
sorbed from the mouth directly into the blood vessels.
Poisonous substances may sometimes be absorbed from the
mouth in sufficient quantities to produce death. If a drop
or two of prussic acid be placed on the tongue or on the
mucous membrane, death occurs in a few minutes,
although not a particle of it has reached the stomach.
Boys who take their first chew of tobacco learn in a dis-
agreeable way that the entire body may be affected by
absorption from the mouth. The absorption in the mouth
is insignificant in amount compared to the absorption that
takes place in the small intestine.

369. The Pharynx (far-inks), a muscular bag ODen-
ing from the nose and mouth, is four and a half inches

208

ELEMENTS OF PHYSIOLOGY

in length and lies against the spinal column. It is
commonly called the throat. There is an air passage
from nose to lungs and a food passage from mouth to
stomach. They cross each other, and the intersection is
called the pharynx. There are seven openings from the

pharynx : one to the mouth,
one below the mouth into the
trachea, one behind the trachea
into the gullet, and two pairs of
openings in the upper pharynx ;
one of these pairs is to the
nasal passages, and the other
pair is into the Eustachian
tubes, which lead to the ears.
When swallowing, all of the
openings close but the one to
the mouth and the one to the
gullet (see Plate VII).

370. The upper part of the
pharynx, and thus the openings
to the nose and ears, can be
closed by raising the tip of the
soft palate, or uvula, against
the spinal column (Fig. i6O.

FIG. 165. — The Mouth wide open

to show the Tongue and Palate. Sudden laughter or coughing

Uv, uvula; Tn, tonsils; C.p., taste pa- while Swallowing may CaUSC

pillae; F.p.t taste papillae. On the , e . j

right side, branches of the fifth nerve the Soft palate tO relax, and

ninth to the then a portion Qf the food Or

drink is sometimes forced into
the nose. The opening to the windpipe can be closed
in three ways: by the vocal cords approaching one
another ; or by the descent of the epiglottis, the carti-
laginous lid of the larynx ; or third, by the tongue
arching itself back over the windpipe. The opening
from the mouth, called the fauces, can be closed by the

THE DIGESTION' 2OQ

contraction of upright muscles, called the pillars of the
fauces, which connect the posterior part of the soft pal-
ate and the base of the tongue. These muscles come to-
gether in the middle like sliding doors. There are two of
them on each side, and the tonsils lie between them. The
tip of the soft palate hangs down between the pillars,
and is called the uvula. By looking into a mirror with
the mouth very wide open and the tongue flattened, you
can see the palates, the pillars, the uvula, and perhaps the
tonsils.

371. The Tonsils ( Fig. 165 ) resemble the lymphatic
glands. They are oval in shape, and lymph cells, resem-
bling white blood corpuscles, are formed in them by mul-
tiplication, and pass out of the tonsils into the saliva as
salivary corpuscles. They are supposed to be germicidal
and protective. Sometimes the tonsils swell, and by press-
ing the soft palate backward and upward, cut off the pas-
sage from the upper pharynx and nose, necessitating
mouth breathing. They are often partly or entirely re-
moved by the surgeon without noticeable injury to the
health.

372. The use of tobacco is a common cause of diseases '
of the throat. It causes a dryness and thirst, and fre-
quently leads those who use it to take alcoholic drinks.
Often the habit of smoking produces a troublesome disease
called smokers sore throat, which can be cured only after
smoking has been discontinued. The heat of smoking
is very trying to the organs, although not so injurious to
them as the poison of the tobacco. A still more dreadful
disease which can be traced to the same cause is that of
tobacco cancer. Persons dying of tobacco cancer lose their
voices in the advanced stage of the disease. This disease
is practically incurable.

373. The Esophagus, or gullet (Fig. 166), opens from the
lower part of the pharynx. It is about nine inches

p

2IO

ELEMENTS OF PHYSIOLOGY

long, and lies along the spinal column behind the trachea.
It has the three layers found elsewhere in the alimentary
canal, and its walls are soft and lie collapsed when no
food or drink is passing. The food is under reflex con-
trol after passing the fauces.
The contraction of the pharynx
presses the food down into the
esophagus. A ring of the mus-
cular tube contracts just above
the morsel. This contraction
runs down to the stomach, forc-
ing the food before it as if a tight
ring were slipped down over the
esophagus. A contraction of any
part of the alimentary canal in
this manner, as if a wave were
traveling along, is called peri-
stalsis. While a horse is drink-
ing, the peristaltic waves of the
esophagus may be plainly seen
along the neck (Plate VII).

374. The Stomach. — The gul-
let pierces the diaphragm to the
left of the center and enlarges
vii). into a pouch called the stomach.

a, vertebral column; b, esophagus; -j^g or^an ljes just under the
c, trachea; d, larynx; e, epiglottis; J

/, soft palate and uvula; g, open- diaphragm, mostly on the left

ing of left Eustachian tube; h, open- ,. J t, ir

ing of left lachrymal duct; *', hyoid side of the abdomen and hall
L°,n«, base°of skuiii ^A^e covered by the lower ribs. It

scroll-like, or turbinated bones. Jg capable of holding about tWO

quarts. When full, it is about a foot long and five inches
broad. Its shape is not easily described (Fig. 167). It is
placed across the abdomen, and its left end is the larger.
Its outline is curved inward above and outward below.
When empty, it flattens and its walls touch, and the

THE DIGESTION

211

mucous lining then lies in deep wrinkles or folds. The
opening where the gullet ends and through which the food
enters, is called the cardiac orifice because it is near the
heart. The opening where the intestines begin and
through which the food leaves, is called the pyloric orifice ;
both openings can be
closed by circular mus-
cles in their walls.

375. Peritoneum. —
The abdominal cavity,
or the portion of the
large cavity of the trunk
below the diaphragm,
has, like the thoracic
cavity, a lining to pre-
vent friction. This
membranous lining is
called the peritonfaim,
and like the pleura, it is
double. It comes
the wall of the
all around, lining it like
a thin sheet, until it

reaches the place under the diaphragm where the gullet
and larger blood vessels (aorta and vena cava) enter, where
it is reflected and courses downward, enveloping the
stomach and other digestive organs. It penetrates be-
tween them by means of foldings and turnings, thus
assisting to hold them in place. The largest fold of all
is called the great omentum and surrounds the small
intestine. It is fan-shaped and its contracted part is
attached to the spinal column for a firm support. The
alimentary canal, beginning with the stomach, may be
said, therefore, to have a fourth layer, or covering, the
peritoneum.

FIG. 167. — The Stomach laid open.

Up a, esophagus; b, cardiac dilatation on left side of
stomach; c, the upper wall; d, the pylorus; e, bile
duct. ^ gall bladder; g, pancreatic duct, opening
with bile duct into h, :', duodenum (see Plate V).

212

ELEMENTS OF PHYSIOLOGY

376. The Peristalsis of the Stomach.— Anything taken
into the stomach causes wavelike contractions in its mus-
cular walls. The food is caused to go from the gullet to
the left of the cardiac orifice, then down to the right and
back again, the circuit from left to right, then from right to
left, taking from one to three minutes, according to the

activity of the peristalsis. The
muscular fibers in the walls of the
stomach are in three layers (Fig.
169); one layer runs lengthwise,
another around, and the third
obliquely, so that the varied con-
tractions cause the food to become
thoroughly mixed with the —

377. Gastric Juice. — This is a
yellowish fluid and consists of
water, having in solution hydro-
chloric acid and two ferments.
These remarkable substances,
although existing in very small
quantities, are able to change the
composition of large quantities of
food. In times of rest, when there
is no food present, the mucous mem-
brane of the stomach is of a pale
red color. But when food is intro-
duced, a change at once takes
place. The membrane becomes

charged with blood and consequently turns to a deep red
color. The gastric juice, secreted by many small glands
(Fig. 168), appears on the walls of the stomach, and peri-
staltic action begins (Fig. 169).

378. The ferment of the gastric juice called rennin acts
by coagulating milk, a change somewhat like the coagula-
tion of the blood. It causes coagulation by acting upon

FIG. 168. — Three Glands of
the Stomach.

t, epithelium at inner surface of
stomach; m, mouth of gland;
/, principal cells of gland; ov,
ovoid cells; c, connective tissue
below and between the glands.

^r'TJfff DIGESTION

213

the proteid part of the milk. It is especially abundant
in childhood. The other ferment, called pepsin, softens the
proteid part of food and reduces it to peptone, in which
form it is soluble in water. Pepsin, however, can act only
when the hydrochloric acid has accumulated to an
amount sufficient to neutralize the alkaline condition caused
by the saliva. This usually requires about thirty or forty
minutes. The hydro-
chloric acid, by its
presence in sufficient
quantity, not only en-
ables the pepsin to act,
but also prevents fer-
mentation of the food
and kills all germs that
may enter the stomach.

379. The saliva con-
tinues its work even in
the stomach until neu-
tralized by the acid.
The pepsin then begins
to act. The outside of
the food particles is
acted upon first, and
this digested part is

then rubbed off by the peristaltic movements, and the
next layer is acted upon. Its action is confined to the
proteids. In fat meat the albuminous walls of the cells
are eaten away and the fat is set free but not digested.
Starch may also be set free from albuminous envelopes.

380. The food is thus reduced to a semi-fluid condition
and is called chyme. A slight absorption may take place
in the stomach, of a portion of the proteids digested there.
Some of the sugar resulting from the salivary digestion of
starch by the saliva, may also be absorbed. Nearly all the

FIG. 169. — A Section through the Walls of the
Stomach. Magnified only 15 diameters.

i, surface of the mucous membrane, showing the
openings of the gastric glands; 2, mucous mem-
brane, composed almost entirely of glands; 3, sub-
mucous or areolar tissue; 4, transverse muscular
fibers; 5, longitudinal muscular fibers; 6, perito-
neal coat.

214 ELEMENTS OF PHYSIOLOGY

absorption of the food takes place in the small intestine,
and it is there likewise that most of the digestion takes
place ; for, upon leaving the stomach, the greater part of
the proteids, sugars, and starches, and all the fats and oils,
remain to be acted upon.

381. After the food has been reduced to chyme, the
pyloric orifice opens every minute or two, permitting a little
of the chyme to escape into the intestine. But if some
hard object, as a button, or a lump of raw starch from
an unripe apple insufficiently masticated, enters the
stomach, the pylorus, after a while, will become fatigued
and will relax and allow it to pass without
becoming semi-fluid (Fig. 170).

382. It is a common notion that digestion
is carried on chiefly in the stomach. Some
physiologists give tables stating that pork
requires five hours for digestion, fried beef
four hours, roasted beef three hours, apples
FIG. 170. — Pylorus, one hour, etc. ; what is meant is that it
/, pyloric sphincter, requires that length of time for these

d, stomach.

foods to leave the stomach, the digestion
being1 far from complete. The tendency of investigation
in the last few years is to show that the stomach is a kind
of storeroom or antechamber which enables us to eat food
in a shorter time, and in which it is stored, being softened
and kept free from germs in the meanwhile, that it may be
delivered gradually to the intestine. There were four per-
sons in the world in the year 1900 without stomachs (this
organ having been removed by surgeons on account of
cancerous or other incurable conditions), and the small
intestine joined to the esophagus. These persons had to
eat very slowly, taking their food in a semi-fluid condition.
383. Retrospect. — Of the thirty or more feet of the ali-
mentary canal, the food, upon leaving the stomach, has
traversed about two feet. Of the fourteen hours required

THE DIGESTION 21$

for digestion, about three or four hours have passed. A
portion of the starch and proteid has been digested and
a small amount of each absorbed by the blood vessels.
The fats have not yet been acted upon.

384. It is essential that the part performed by each
prior organ should be well performed, for this determines
whether the changes in the food in the next organ shall
be easily and completely accomplished. If the food is
thoroughly masticated in the mouth and the saliva well
mixed with it, this alkaline condition excites the flow of the
acid gastric juice, which otherwise would be scanty. If
the gastric juice is strong and acts freely upon the food, the
acidity of the food as it leaves the stomach and enters
the small intestine, excites the flow of the alkaline intes-
tinal juices.

385. THOUGHT LESSON. Indigestion.

I. A Fetid Breath.

1. Name three causes of bad breath.

2. Let us investigate whether indigestion could cause a
bad breath. In what kind (two qualities) of weather does
meat spoil the quickest?

3. Suppose that meat or other food is put into a stomach
with its gastric glands exhausted and its muscular walls
tired out, what will be the rate of digestion, and what
might happen to the food ?

4. Odorous contents of the stomach (e. g. onion) can be
taken by the blood to the lungs.

After answering mentally the above points, write in a
few words a logical statement of how indigestion may
cause a bad breath.

II. A Coated or Foul Tongue.

1. When the doctor visits you, at what does he first look ?

2. What sometimes forms on old bread ?

3. Do you think such a growth possible on undigested
food in the stomach (§ 309)?

216

ELEMENTS OF PHYSIOLOGY

4. The microscope shows the coating on the bread to be
a vegetable growth. If it forms on the walls of the stomach,
it may extend to what ?

III. Stomach A che.

1. How can you tell whether fruit preserved in a sealed
glass jar is spoiling ?

2. What connection is there between belching at times
after eating too freely of sweet or starchy food and the

observation above ?

3. Why does belching sometimes
give relief to an uneasy stomach ?

4. Can you, by using these facts, ex-
plain a cause of stomach ache ?

Be ready to give logical explanation
in class, of cause of bad breath, furred
tongue, and stomach ache.

386. The Small Intestine. — When
the chyme passes the pylorus, it enters
the small intestine, which is a tube
about as large around as the thumb,
and about thirty feet long, lying coiled
in the central part of the abdominal
cavity. The first part of it, about ten
inches in length, is called the duodenum
(from a word meaning twelve, because
its length is twelve fingers' breadth) (Fig. 167). The
mucous and submucous coats of the small intestine are
wrinkled by numerous folds which are crescent-shaped,
since no single fold goes entirely around the tube (Fig.
171). The folds are so numerous that they occupy almost
the entire inner surface. The small intestine is the chief
organ of absorption as well as of digestion, and the ab-
sorbing surface is greatly increased by the folds. On and
between the wrinkles are innumerable tiny projections called
villi (Fig. 172). Each villus contains a loop of blood

FIG. 171. — A Portion of
Small Intestine cut
open to show the Folds
on its Inner Surface.

THE DIGESTION

217

•pi.

vessel and a very small lymphatic called a lacteal. Since
the villi are so thickly placed as to cover the entire mucous
coat of the intestine like the fibers in a piece of velvet,
the absorbing surface is enormously increased.

The digestive fluids that enter the small intestine are the
pancreatic fluid from
the pancreas, the bile
from the liver, and
the intestinal juice
from the small in-
testinal glands (Figs.
172 and 174).

387. The Pancreas
and its Secretions. —
The pancreas, or
sweetbread, is flat,
narrow, and about six
inches long. It lies
behind the stomach,
and tapers toward
the left, ending above
the left kidney. Its
shape has been com-
pared to a dog's
tongue and like the FlG> I72> ~~ To show the Structure of the Wal1 olf

the Small Intestine.

root of the tongue, , .

v, villi, and g, glands of the mucous membrane;

it bends downward c.m., circular muscle layer; Im, longitudinal muscle
, layer: /, peritoneum, or serous coat.

at its broader end,

where its duct leaves it and joins the bile duct just before
emptying into the duodenum. Its internal structure re-
sembles the salivary gland, and it is called by the Germans
the abdominal salivary gland. The amount of digestion
accomplished in the small intestine is greater than in any
other division of the canal, and the pancreas is the most
active and powerful of all the glands. Its secretion, the

218

ELEMENTS OF PHYSIOLOGY

pancreatic juice, is alkaline, and contains three ferments,
one of which (amylopsin) is hardly to be distinguished
from the ptyalin of the saliva, and continues the. digestion
of the starchy food ; another (trypsin) has an action
similar to pepsin, and digests proteids ; while the third
(steapsin) begins the digestion of an important class of

foods, the fats, which have not
heretofore come in contact with
a digestive fluid that could act
upon anything more than the
proteid envelopes of the fat cells
(see Plates).

388. Digestion of Fats. — Fats
are digested not by going into
solution, but by the large globules
of fat being broken into very

FIG. 173. — Semi-diagrammatic minute globules. Such globules,

View of Two Villi of the Small „ . . .. ., . , .

intestine. Magnified about floating in a liquid, form what is

50 diameters. called an emulsion. Milk is an

a> substance of the viiius; t, its epi- emulsion of cream. It is the

thelium; c, a, the artery and vein,

with their connecting capillary net- Cream in SWCCt milk which glVCS

work which envelopes and hides f, •, .-\ •> •. r i

the lacteal that occupies the Cen- it the white appearance, for the

ter of the villus and opens into a g^buleS of fat reflectthe light,
network of lacteal vessels at the base. j

When it is churned these minute

particles touch and adhere, forming butter. Fats are not
acted on by acids, but they are acted upon by alkaline
fluids. The steapsin ferment from the pancreas, aided by
the alkaline bile from the liver, emulsifies the fats, and pre-
pares them for absorption.

389. Absorption of the Fats. — The fats are absorbed by
the lymphatic system. Many minute lymphatics called
lacteals (Fig. 173) are found in the villi of the intestines,
and the epithelial cells of the mucous lining take up the
fat and transmit it, slightly changed, to these lacteals,
which unite one to another and empty into the thoracic

THE DIGESTION

219

as to show the Bile
Duct (a) and the
Pancreatic Duct (b)
opening by a Com-
mon Orifice.

duct. Where does this duct empty ? The fats are thus

taken into the blood stream.

390. The Intestinal Glands. — Besides the two large

glands, the pancreas and liver, there are

a great number of very small glands (Fig.

172) which furnish a digestive fluid to

the intestine. The intestinal glands are

scattered throughout the lining membrane,

and their secretion is called the intes-
tinal juice. It is difficult to isolate and

to study because of the minuteness of the

glands, and although their functions are

not fully known, it has been proven that

their secretion can digest cane sugar and

maltose and change them into grape sugar,

or glucose. If cane sugar is injected into

the arteries, it is excreted from the body unchanged.

This proves that the body is incapable of assimilating

cane sugar until it is digested.
391- Forms of Sugar and
Starch. — Cane sugar is found
in sugar cane, sorghum, and
sugar beets. Milk sugar is
found in milk. Malt sugar
is produced by the action of
saliva upon starch. Grape
sugar (and fruit sugar, which
intestine is nearly the same) is the
sweet element in fruits and
honey.

Malt sugar, while passing
through the mucous mem-
brane of the intestine, is con-

FIG. 175.— The Digestive System. verted into grape sugar, and

in this form it is absorbed into the blood. It may be

— Pancreas

-V— Small

Vermiform .
Appendix

22O

ELEMENTS OF PHYSIOLOGY

produced artificially by the action of vegetable diastase,
which resembles ptyalin or the ferment found in saliva.
Glucose, produced artificially by boiling starch with dilute
sulphuric acid is of the same chemical composition as
grape sugar, but the presence of sulphur and other chemi-
cals interferes with its usefulness as a food.

Dextrin is intermediate between starch and sugar.

Starch, unlike the sugars, is insoluble in cold water.

392. Analysis of Digestion. —

1

Part of alimen-
tary canal.

Glands.

Secretion.

Food acted
upon.

2

Mouth.

Salivary
(three).

Saliva.

Starch.

3

Stomach.

Gastric glands.

Gastric juice.

Proteids.

4

Small intestine.

Liver.

Bile.

Fats.

Pancreas.

. Pancreatic
juice.

f Starch. See

\ Proteids. See

( Fats. See

Intestinal
glands.

Intestinal
juice.

Cane sugar.

5

Large intestine.

Absorption. Amount of diges-

393. THOUGHT LESSON.

(Answers to be found by reference to table called
"Analysis of Digestion.")

1. In which of the digestive organs is only one kind
of secretion furnished from glands ?

2. In which organ are three kinds of secretions fur-
nished it by glands ?

3. Which classes of foods go through the lymphatics ?

THE DIGESTION

221

4. Which classes of foods go through the liver ?

5. Which classes of foods are digested in only one
organ ?

6. Which classes of foods are digested in two organs ?
How do the facts given in the table show —

7. That the pancreatic juice is the most important of
the digestive secretions ?

8. That bread needs to be kept in the mouth for a
longer time than lean meat.

What it is
changed to.

How it gets
into the blood.

What it will be
used for.

Final product
of oxidation.

1

Sugar.

Capillaries of
portal vein.

Work, heat,
and fat.

Carbon dioxid
and water.

2

Peptones.

Ditto.

Building tissue.

Chiefly urea.

3

Emulsion.

Lacteals of lym-
phatic system.

Heat, work,
and fat.

Carbon dioxid
and water.

4

second line.

third line.

fourth line.

See second line.

tion here is insignificant.

5

9. That lean meat (a form of proteid) fried so that the
grease soaks into it, is hard to digest? (Suggestion:
Where is fat digested? Where should the digestion of
proteids begin ?)

10. That doughnuts, or batter-cakes, or any starchy food
cooked so as to become grease-soaked, are hard to digest.

394. How the Food gets into the Tissues. —The absorp-
tion of the emulsified fats by the lymphatics has been

222

ELEMENTS OF PHYSIOLOGY

described. The digested starch (glucose) and digested cane
sugar (glucose) and the digested proteids (peptones) pass
into loops of the blood vessels contained in the tiny projec-
tions called villi, and are carried to the liver. Both the
small amount of these substances which is absorbed by
the stomach, and the large amount which is absorbed
from the small intestine, are taken by means of a system
of veins called the portal circulation (Fig. 178), to the
liver, where they may be stored or may pass through
the liver and vena cava to the general circulation. The
mineral substances, iron, lime, sulphur, and phosphates are
contained in the proteid food and are digested and ab-
sorbed with it. Water and salt do not require digestion.
It was formerly believed that the food
passes into the lacteals and capillaries
strictly according to the physical law of
osmosis which governs the passage of
fluids through dead membranes. It is
now believed that the epithelial cells lin-
, ing the canal take up the food and give it
into the absorbent vessels by a process
resembling secretion ; but osmosis aids

FIG. 176. -The Valve the PrOCCSS.

between the Large 395. The Large Intestine or Colon

and Small Intestine. (p. ^ {& ^^ fiye ^ 1()ng ^

a, small intestine; e, large

intestine; d, c, valve; walls are drawn into pouches, or puckers,
6, appendix. ^y bands of muscles running lengthwise

along it. The small intestine joins it in the lower part of
the abdomen on the right side (Fig. 176). The junction is
not at the end of the large intestine but above the end.
The part below the junction is called the c&cum. Attached
to the ccecum is a small tube called the vermiform appendix.
Above the juncture the large intestine is called the colon..
The ascending colon runs up along the right side nearly
to the waist. It is then called the transverse colon, and it

THE DIGESTION

223

Acol

comes forward and crosses just in front of the lower line of
the stomach. It then retreats to the rear wall and passes
downward, being now called the descending colon. Near
the left hip it makes a
double bend called the
sigmoid flexure (from.
sigma, the Greek letter
S). The nine inches re-
maining are without the
pouched appearance,
the walls being smooth ;
this part is without
bends and is, therefore,
called the rectum (from
Latin rectus, "straight"),

396. Absorption in
the large intestine is
very active and its con-
tents soon lose their
fluidity. Although it is
mostly the watery por-
tion that is absorbed,
any digested food that
may have escaped ab- FlG
sorption in the small in-
testine, is absorbed by R* riSht; L> left; "> esophagus; st, stomach; Py,

pylorus; duo, duodenum; ccec, caecum; A. col,

the COlon. HOW Saving ascending colon; T. col, transverse colon; D.col,
-, * ,-, , i descending colon; R, rectum.

and economical the body

is ! All the undigested and indigestible food gathers in the

sigmoid flexure, and descends, at intervals into the rectum.

THE LIVER

397. The Liver not merely a Digestive Gland. — The liver
has three functions, (i) The bile secreted by it goes down
the chief duct and "backs up" into the gall bladder, where

ccec

verm

_ The Alimentary Canal in the
Abdomen.

224

ELEMENTS OF PHYSIOLOGY

it is stored until food is eaten, when it enters the alimentary
canal and aids in the digestion of the fats. (2) It serves
as a storeroom for digested food. You learned that all
foods but the fats were carried to the liver when absorbed

(Fig. 178). Some of them
are stored there and given
out gradually as needed.
(3) The liver is an excretory
organ. As the blood contain-
ing the food passes through
it, poisonous substances in
the blood from the tissues,
or poisons that may be in the
food, are destroyed and the
products resulting from the de-
struction are sent out of the
body by either of two routes :
by way of the bile duct and
alimentary canal or by way
of the blood vessels and kid-
neys.

As only one of these three
functions is strictly digestive,
it is more logical to treat the

carrying the Blood from the Viscera liver Somewhat apart from

to the Liver' the digestive organs.

398. Its Duty as a Guar-

from each other, /.pancreas; j/, spleen; fa^, fhe food (except the

ac, cd, large intestine. The transverse

colon and the small intestine have been re- fats) HlllSt paSS the tCSt in the

liver before it can reach the

system. All the blood in the body passes through it once
every three or four minutes, and as it passes it is purified.
The waste products resulting from the work done in the
body are made more soluble, so that they can be carried
through the kidneys. The yellow color of the bile is due to a

THE DIGESTION 22$

pigment resulting from the destruction in the liver of worn-
out red corpuscles. The bile is partly an excretory prod-
uct, but such is the economy of the system that it serves
to aid digestion, and to keep the alimentary canal in an
aseptic condition on its way out of the body. A man could
not smoke were it not for the liver. This organ takes up
the nicotine, if not too great in amount, and destroys it.
If one drinks alcohol, the liver endeavors to oxidize it and
get rid of it, so that the body may not suffer harm and in-
jury from it, and oftentimes the liver of a habitual drinker
is crippled or destroyed by its long struggle with alcohol.

399. It has been shown by experiments upon frogs and
other animals that twice as large a dose of poison is required
to kill an animal that has a liver as to kill one that has
been deprived of this organ. Similarly, it requires twice
as much poison to kill a man when it is given through the
stomach and passes through the liver, as when it is injected
through the skin. Those who take morphine by hypoder-
mic injection are more hopelessly bound to the habit than
those who take it by the mouth.

400. A man would live many years longer than he does
if he were not all the time producing waste products in his
body by his ordinary activities. The excretory organs are
taxed to remove them. In the young child as it is growing
and developing, the skin is so active, the kidneys are so
healthy, and the liver is so vigorous, that the waste is all
removed and the blood is pure. That is why a healthy
child has so sweet a breath, such bright eyes, and so fair a
skin. When he becomes old it is different. The same is
true of a dog ; the puppy's breath is pure, its body is clean,
so that it may lie in a lady's lap or on a sofa and leave no
unpleasant odor. But when he is old, the dog becomes so
offensive that he has to be driven out of the house. The
strong odor results from the accumulation of waste sub-
stances in the body.

Q

226 ELEMENTS OF PHYSIOLOGY

401. Gross Anatomy of the Liver. — The liver is the largest
gland in the body. It is of a reddish brown color and
weighs about three and one half pounds. The upper and
front surfaces of the liver are very smooth and even. The
under surface is very irregular ; it is here that the various
vessels with which this active organ is supplied make their
entrance or exit. It is located under the right portion of
the dome of the diaphragm, and its lower edge reaches a
little below the border of the thoracic cage. (Does its left
end overlap the stomach? See Plates.) Its connecting
vessels, besides the lymphatics, are the hepatic artery from
the aorta, bringing pure blood ; the portal vein, bringing the
digested food ; the hepatic vein, carrying impure blood to
the vena cava ; and the bile duct, carrying the bile to the
intestine. The bile duct, on its way from the liver, gives
off a side branch to the gall bladder. This is a little dark
green bag, in which the bile is stored until it is required for
digestion (Plates III and IV).

402. With each inspiration the liver is pushed downward
and compressed by the diaphragm, the blood being forced
out toward the heart, and it fills again as soon as the breath-
ing muscles relax. This rhythmic compression is of great im-
portance in keeping the blood supply to the liver fresh and
pure, and preventing congestion in it. By tight clothing
the liver is often forced downward, out from the cover of
the ribs, and becomes permanently displaced. As a result,
other organs, lower in the abdomen and pelvis, are crowded
upon each other and also become displaced. The circula-
tion in the liver is diminished, and hence its activity is
decreased and the complexion loses its freshness.

403. Circulation through the Liver, or Portal Circulation. —
The portal vein and its function have been mentioned (Fig.
1 78 ). When it enters the liver, it does a very unusual thing ;
in fact, it conducts itself as no other vein in the body does,
except some of the veins in the kidneys. It subdivides

THE DIGESTION

227

into capillaries. Thus the portal vein (Latin porta, a gate,
since it enters under a kind of archway) both begins and
ends in capillaries, for it begins in the capillaries of the
digestive tract and ends in the capillaries of the liver. After
these capillaries have passed in among the cells, they unite
again to form the hepatic veins, which go directly to the
ascending vena cava. There is another large blood vessel
in the portal circulation. This is the hepatic artery, which
enters the liver directly from the aorta and supplies the
liver cells with arte-
rial blood with which
to repair themselves
and carry on their
work (Plate VII).
The capillaries from
this artery unite with
those of the portal
vein in forming the

hepatic Vein. A COW'S FIG. 179. — Diagrammatic Representation of Two
v . Hepatic Lobules.

liver, cut in two,

The left-hand lobule is represented with the intralobular
vein cut across: in the right-hand one the section takes
the course of the intralobular vein. /, interlobular
branches of the portal vein; h, interlobular branches
of the hepatic veins; s, sublobular vein; c, capillaries
of the lobules passing inwards. The arrows indicate
the direction of the course of the blood. The liver-cells
are represented in only one part of each lobule.

shows in places small
gaping holes, which
are branches of the
hepatic veins.

404. Minute Anat-

omy of the Liver. — If you examine the surface of a
piece of liver obtained from the butcher, you will find
it to be of a dark red color, and mottled over with
little areas, each measuring about one twentieth of an
inch across. These are the round lobules of the liver
arranged around a branch of the hepatic vein (Fig. 1/9).
The capillaries of the portal vein and hepatic artery and
the branches of the bile duct pass between these cells.
Study carefully Figure 180, which represents a segment of a
lobule. When you understand the circulation in a lobule,

228 ELEMENTS OF PHYSIOLOGY

you will understand the circulation in the entire liver, for
a lobule is the liver in miniature. Represent a lobule by
a wagon wheel. The rim corresponds to the capillaries
of the portal vein and hepatic artery circulating around the
lobule. The spokes correspond to the two kinds of cap-
illaries united and on the way to the hepatic vein in the

hub, which will take the blood
away from the liver. Between
the spokes are located the hard-
working liver cells which get
oxygen and food from the capil-
laries in the spokes, and relieve
themselves of impurities by
means of the finest bile ducts
and lymphatic ducts, which be-
gin among the cells (Fig. 181).
What are the two large vessels
which bring material to the liver ?

FIG. !8o.- Microscope, high power. Wfa t ^ t j vessels

Diagram of a Portion of a Lobule

of the Liver, showing the Blood ( besides the lymphatics) which
wietShS^uidnd BilC DUCtS inJ6Cted take material out of the liver?

A, branch of portal vein sending capil- ^' Th* LivCT RS & Storeroom.

larics to open into E, a branch of the If a frOg be dug Up in the first

hepatic vein which lies in the middle .

of the lobule; B, a lymphatic; C, part of its Winter sleep, and itS

Wver be examined under the
microscope, the cells will be
found swollen and full of gly-

cogen, a substance stored up for the winter needs of the
frog. It is a carbohydrate material resembling starch and
made from digested sugar. The liver cells of a frog which
has just come out in the spring will be found shrunken and
containing no glycogen (Fig. 182). If a starving rabbit be
killed and its liver cells examined, no glycogen will be
found, but the liver cells of a rabbit which has recently
been fed on turnips will be full of glycogen. If two

THE DIGESTION

229

FIG. 181. — Diagram to show the Termination of a
Fine Bile Duct.

b, small bile duct becoming still finer at b' ; /, hepatic cells;
c, capillaries cut across.

rabbits be well fed and one kept in a cage and the other

hunted around all day, much glycogen will be found in

the liver of the quiet rabbit, and very little in the liver

of the hunted one.

The glycogen stored

up is used during

muscular work or

starvation.

406. The sugar

absorbed by the

small intestine

reaches the liver

through the portal

vein. It is taken

up by the liver cells

and changed into

granules of glyco-
gen, to be turned

into sugar again during times of hunger and hard work.

Thus only a small amount of sugar is allowed to enter

the circulation at one time, only ij ounces in every

1000 ounces of arterial
blood. If more than this
quantity enters the blood,
sugar passes out through
the kidneys, and the func-
tion of the kidneys may be-
come disordered, a condi-
diabetes."

Urea is the chief
waste product which results

from the breaking down of proteid, and it is believed that
the nitrogenous urea as well as the carbohydrate glycogen
is formed by the liver. An excess of proteid, such as
lean meat and cheese, in the diet, produces an increased

FIG. 182. — Liver Cells of Dog after a Thirty-
six Hours' Fast ; also Fourteen Hours after tion known as

230 ELEMENTS OF PHYSIOLOGY

excretion of urea through the kidneys. It is obvious that
excess of food and lack of exercise may lead to the chok-
ing up of the iiver cells with food products which are
not required. This condition may be relieved by a spare
diet and by vigorous exercise. The poor, overworked liver
should not be blamed, however, nor the statement made
that "the liver is not acting." At the very time the com-
plaint is made, the skin and eyes may be yellow, showing
the presence of too great a quantity of bile, which is a
product of the activity of the liver.

408. Biliousness may result from three causes: (i) The
first and most usual form of biliousness is not bilious-
ness at all, but is caused by fermentation and other
forms of indigestion, and by the poisonous products
therefrom entering the blood. (2) Stoppage of the chief
bile duct because of congestion, which extends to it
from the stomach. This congestion is caused by irri-
tation of undigested food (§ 597). (3) The liver cells
and ducts may become choked up from excessive food

(§ 407).

409. Alcohol in the Liver. — When alcohol is drunk, the
portal vein carries it directly to the liver. There the
alcohol greedily uses up the oxygen needed by the liver
cells for their vital operations. This prevents natural
action of the liver, for its cells have not enough oxygen to
do their work properly. All physicians know that a drunk-
ard's liver presents a greatly modified appearance. The
alcohol does not build up useful tissue, but if taken in
weaker form, such as beer and wine, it promotes an abnor-
mal deposit of fat in the cells.

410. Drinking whisky and other distilled liquors causes
the connective tissue of the liver first to increase in amount
and afterward to shrivel and harden, drawing up into many
little knots. This condition is called " hobnailed" or "gin
drinkers' liver."

THE DIGESTION 231

411. Influence of Carriage and Dress on Digestion. —

Faulty carriage of the body and relaxation of the ab-
dominal muscles, which lessens the abdominal type of
respiration and diaphragmatic motion, are among the most
frequent causes of sluggishness in hepatic circulation and
secretion. Disorders of the stomach and intestines are
likely to produce abnormal conditions of the liver. Im-
proper dress aggravates all of these conditions.

Free and properly related movements on the part of the
stomach, liver, and intestines are necessary for the correct
performance by these organs of their natural functions.
A certain amount of tension within the abdomen is neces-
sary if the organs of that region are to be held in their
proper places and relations. When the body is held erect
and the chest is kept raised to its normal position ; when
the abdominal muscles are strong and are not allowed to
relax and thus favor the descent of the organs, this
abdominal tension and the proper relations of the organs
are possible. Mothers should dress their children so that
the chest may have the greatest possible freedom of mo-
tion. All garments should be suspended from the shoul-
ders, thus preventing the downward displacement of the
stomach, intestines, kidneys, liver, etc. Physicians who
have given the subject careful study agree that more
than fifty per cent of the women of civilized nations have
developed the condition known as enteroptosis, which means
that of the stomach, the intestines, frequently the kid-
neys, and sometimes the liver, are dragged downward and
remain permanently out of proper position. This condi-
tion is largely responsible for the debility, backache, head-
ache, biliousness, and early loss of complexion with which
so many women of civilized countries are afflicted. Even
if suffering from the enteroptosis caused by methods of
dress, those who have strong constitutions and who keep
the body healthy by living much out of doors, may enjoy

232

ELEMENTS OF PHYSIOLOGY

moderate comfort. The greater proportion of women,
however, lack these conditions and hence suffer to a
greater or less extent from the symptoms mentioned.

412. The mistake in regard to dress begins so early in
life that the wearer almost ceases to consider the dis-
comfort arising therefrom. Many women say that their

_^>*s>

FIG. 183.

The breastbone cannot be moved down by
a corset. Use its lower end for a sta-
tionary point, in comparing Figs. 183
and 184. How much have the liver and
stomach descended ?

FIG. 184.

How far have the kidneys been moved ?
Has only the middle of the transverse
colon descended or all of it? Is the
waist of Fig. 183 deformed more than
the usual amount ?

dress is perfectly comfortable, because they do not know
what comfort and freedom is. Dr. Kellogg found the aver-
age waist measure of girls from 9 to 1 2 years of age to be
23 \ inches, and he found the waist measure of young ladies
from 1 8 to 30 years of age to be 23 \ inches. If their
waists had been allowed to grow as God designed, they
would have become 28 or 30 inches in circumference. In
all these years the bones, muscles, digestive and other

THE DIGESTION 233

organs had been growing, but the waist had not. The
organs had been growing out of place. The muscles of
the trunk had not been growing, because their exercise was
prevented by tight skirt-bands or corsets. The weak
abdominal muscles become distended by the weight of
the organs, and the abdomen sags downward and extends
too far forward. The proper support being removed, the
stomach, liver, kidneys, and other organs sag downward
and drag and pull upon their points of attachment and
cause pain and distress in all parts of the trunk, especially
in the back, because of the pulling and stretching of the
nerves leading from these organs to the spine.

413. Having worked perseveringly to get the organs
down out of the waist and make it small, the woman would
now give treasures to get them back again. The contor-
tions such as the " straight front " and " Grecian bend "
are attempts to conceal deformities of waist and abdomen.
The cause of the trouble dates back to the year the grow-
ing girl began to wear her skirts tied around the waist in-
stead of sewed to the upper part of the dress. Growth at
the waist immediately ceased. If she had only waited, the
chest and hips would have developed and the waist would
have become rightly proportioned soon enough. It is said
that a majority of women are sufferers from headache,
backache, and other weakness which could have been obvi-
ated by comfortable and therefore graceful clothing. This
want of foresight has made invalids and nervous wrecks of
thousands of women, who try one surgeon and physician
after another, seeking relief. Such a woman is unsuited for
the proud position of presiding over the household, her
diseases cast a gloom over the family life. The world is
not so bright to her, and life is not so joyous as it should
be. Yet many a delicate woman would have been able
to retain her health if she had not had a dissipated and
drunken, or a nervous, tobacco-soaked, husband. It is

234

ELEMENTS OF PHYSIOLOGY

possible also that many a man would have been able to
bear up through the struggles of life and finally to suc-
ceed, instead of succumbing to stimulants and dissipation,
if he had not been burdened with a hysterical invalid for
a wife, instead of a brave, cheerful, and healthy woman.
The drooping lily style of woman has
become very distasteful to men; the
drinking, dissipating man is becoming
equally repulsive to women. Health
is an indispensable foundation for
happiness.

THE KIDNEYS

414. The kidneys lie one on each
side of the vertebral column, against
the rear wall of the abdomen, on a
level with the lower ribs. They are
purplish red organs, about four inches
long and two inches broad, and some-
what bean-shaped. A man's kidney
(Fig. 185) is very much like a pig's

FIG. 185.— Kidneys and kidney, which you may have seen.

Bladder. J . . J

415. A large artery, the renal ar-

K, kidneys; Ur, ureters; . . . . ,

/?/, bladder: i, openings of tery, leads from the aorta to each
tt kidney, and a large vein, the renal

aom; v.c.i., inferior vena vem leads from each kidney to the

cava (see Plate V).

inferior vena cava. There also passes
out from each kidney a white tube called a ureter. The
two ureters run down the back and open into the bladder
(Plate V).

416. Function. — Urea is the most important substance
excreted by the kidneys. It is brought by the blood to the
kidneys, and you learned that it is probably formed in the
liver. It is a nitrogenous substance, and is more abundant
if a large amount of proteid food is eaten.

THE DIGESTION

235

417. In summer, when
the circulation in the skin
is active, the secretion of
the kidneys diminishes in
amount. On the other hand,
cold drives the blood from
the surface to the internal
organs, and the secretion of
the kidneys is increased,
although probably but little,
if any, more urea passes off.

418. The blood leaving
the active kidney is still
of a bright red color. It is
probably the purest blood
in the body. Can you ex-
plain why this is so.

FIG. 186.-— Section of the Kidney.

Ct, cortex; AT, medulla; .Py, pyramid;
P, pelvis; U, ureter; RA, renal
artery.

CHAPTER XIV
HYGIENE OF DIGESTION

419. Is Good Health " Catching " ? — A wit once said that
if he had been consulted at the creation of the world, he
would have made good health " catching " instead of dis-
ease. Observations show that happiness, industry, health,
faith, and other of the strong elements that make up life, are
more contagious than misery, idleness, sickness, worry,
and the other weak elements that tend to destroy life.
Fear causes a tightening of the muscles and a waste of
energy, as well as oppressed breathing and a lack of oxy-
gen. Courage brings calm, full breathing which purifies
the blood, and a steady and economical use of the muscles
which saves the vital energy. A brave and cheerful
visitor can inspire an ailing friend and assist in his re-
covery. A happy, unselfish teacher or pupil can dispel
worry or gloom, and impart strength and increased power
for work to the whole school. The body tends to health
and not to disease. The dyspeptics that we see have been
able to break down their health only after long-continued
attacks upon it, and outrages many times repeated. Fresh
air brings health, and forces its way into the home to
bring it, but the dyspeptic made every attempt to keep it
out. Sunshine brings health, but he shut himself up in a
stuffy ill-lighted office, a slave to dollars or to fame. He
curtained the sunshine out from the home to protect the
carpets and hangings from fading. Exercise brings health,
but the promptings to stir about, to walk, to run, or to work

236

HYGIENE OF DIGESTION

with the hands, were repressed until the impulses ceased.
When activity was lessened, the appetite for food dimin-
ished, but instead of following the prompting of nature, he
sprinkled more salt and pepper and other condiments upon
the food, that he might eat with an unnatural appetite.

420. By keeping up these artificial ways for months and
years, he at last succeeded in breaking down his health. It
took more perseverance to weaken the body than it will
take to make it strong again. There must be a return to
reasonable ways of living with trust in the inherent ten-
dency of the cells to restore soundness when given a
chance. If, however, he commits the folly of thinking
that months are not needed for recovery, but that disease
brought on by months or years of wrong living can be
cured in a few days by taking magical drugs and patent
medicines, he will probably injure himself still more and
lose his chance of recovering sound health.

421. Environment of Primitive Man. — It is believed that
the race originally did not dwell in houses, and had few
tools or cooking utensils. Man probably first lived in the
tropics and subsisted upon the fruits which ripened in the
never-ending summer, and, as he migrated to the colder
climates, subsisted upon the results of the chase. That
individual who refused to peel his apples because, as he
said, Adam had no pocket knife, and slept with his windows
open because Adam had no house, had a right principle in
view. If his teeth were as sound as the teeth of primitive
man, and his habit of mastication as thorough, the peeling
would be only an aid to digestion.

422. Man possesses a stomach intended to digest the
pure food of the forest, obtained by activity in the open
air. If a man eats plain food and leads an active life, his
appetite is a perfect guide. If he does not, it is unsafe to
trust to the appetite alone, for the reason that he lives
under conditions unlike those for which this instinct was

238 ELEMENTS OF PHYSIOLOGY

built up. A cow's appetite is a certain guide to her among
poisonous plants and berries, yet she will eat a bucket of
paint and harm herself ; this is beyond the range of her
inherited habits. Even if man's instincts had their early
strength, they could hardly guide him among the many
food concoctions and preparations undreamed of by primi-
tive man. We can train our taste into wrong ways, and
we can likewise train it into right ways and into liking
food that we know is wholesome.

423. The uncertainties of man's early savage life, the
times of drought or of ill luck in hunting, accustomed his
cells to periods of starvation and repletion, of feast and of
famine. His organs could withstand irregularity better
than they could withstand continuous scarcity or overfeed-
ing, continuous overwork or idleness. The Indian lies
around the camp and gorges himself in times of peace and
plenty, his cells laying up strength which enables him to
follow the trail or the chase for days at a time, going
sometimes fifty miles a day. It is said that the business of
one age becomes the recreation of the next.

424. It is found that returning to natural habits by
going on camp hunts and fishing trips is one of the most
effective hygienic measures for the restoration of health.

425. Hobbies about Nutrition. — The subject of food and
digestion is a more complicated one than that of exercise
or breathing, and more common sense is required to master
it. Therefore, more persons fail to master it, and allow
their minds to come to rest on some one fact or view of
the subject and so become extremists.

426. Hot Water Fad. — Some would cure every digestive
ill by means of water. Their belief is "water internally,
externally and eternally." They sometimes drink it as hot
as it can be borne, yet hot water is very relaxing to the
walls of the stomach and weakens the flow of the gastric
juice. This extreme belief arose from the fact that

HYGIENE OF DIGESTION 239

h.ot water removes the mucus from a stomach suffering
from catarrh (or congestion) and diminishes the activity of
the gastric glands if too much acid is being secreted.

427. Raw Food Fad. — Some persons have a fad called
the raw food doctrine, and eat no cooked food. They
should consider that man's digestive organs are not as
vigorous now as they were ages ago, before he learned the
use of fire. This fad is a reaction from bad cooking.
Cooked vegetables are more likely to ferment in a weak
stomach than raw vegetables. The thorough chewing
required by raw food is an advantage to digestion.

428. No Condiment Fad. — Some persons will not have
condiments or any kind of seasoning, not even salt, in their
food. This is because many cooks destroy the natural
flavors of the food by bad cookery and hide the result by
high seasoning. There are many delicate and delicious
flavors of grains, fruits, and fresh vegetables that a natural
appetite takes pleasure in ; but because of long use of badly
cooked and highly seasoned foods the sense of taste in
many persons has become so depraved and dull that they
have only five kinds of taste left : the taste for grease, salt,
pepper, vinegar, and sugar. Their dull nerves require
everything to be very salty or peppery or sweet or greasy
or sour.

429. Other Fads which may be mentioned are the vege-
tarian fad, distilled water fad, fasting fad, no breakfast
fad.

430. THOUGHT LESSON. Cooking. Meat. — i. In mak-
ing soup, why should the meat be put in while the water
is cold ?

2. In roasting meat, why should the oven be hot at
first, and more moderate afterward ? How should you
regulate the temperature in boiling or stewing meat ?

3. What happens to salt or anything salty on a cloudy,
damp day ? This is because the salt attracts . This

240

ELEMENTS OF PHYSIOLOGY

shows that meat should not be salted until after it has
been cooked, because if salted before, the salt will .

4. Very - — meat should never be broiled, because
broiling does not it. Such meat should be —

b ed or st ed.

5. Meat is allowed to become grease-soaked when it is

by - - cooks. The two ways to prevent this are to

have the grease very , use very , simply greasing

FIG. 187. — Teeth of Cat.

FIG. 188. — Teeth of Man.

FIG. 189. — Teeth of Cow.

FIG. 190. — Teeth of Hog.

6. Bread. — Bread crust causes the to be used more

and cleans them. It will not together in the stomach

like the crumb. It increases the quantity of the , and

is more digestible than the crumb, since the has been

changed by slow heat to . Therefore loaves or bis-
cuit should be [large or small ?] and they should [touch
or be separated ?] in the pan.

How can you tell whether the oven has been too hot
while the bread was cooking ?

HYGIENE OF DIGESTION 241

431. Classification of mammals according to food : — •

CARNIVORA, OR
FLESH-EATERS.

HERBIVORA, OR
HERB-EATERS.

OMNIVORA, OR

ALL-EATERS.

FRUGIVORA, OR
FRUIT-EATERS.

Examples.

Cat, dog, lion,
tiger, bats.

Cow, sheep,
horse, camel.

Hog, peccary.

Man, ape,
monkey.

Length of
Alimen-
tary canal.1

3 times length
of body.

30 times length
of body.
Stomach with
five cham-
bers.

10 times length
of body.

12 times length
of trunk or
body.

Teeth.

Pointed for
tearing flesh.
Canine teeth
long.

Made of alter-
nate layers of
enamel and
dentine, form-
ing ridges for
grinding.
Canines lack-
ing.

Cutting teeth
project in
front.
Canines form
tusks.

Teeth of even
length, close
together. No
space between
teeth.
Canines not
projecting.

Extremi-
ties.

Sharp claws.

Hoofs.

Hoofs.

Flattened nails.

Colon.

Smooth.

Sacculated.

Smooth.

Sacculated.

432. THOUGHT LESSON. Comparison of Mammals. —

Which of the kinds would probably have quickest digestion ?
Slowest ? Which eats food that would spoil if not quickly
digested? Which eats food that would keep sound? Is
there an appropriate relation between extremities and teeth?
Which kind of mammals has closest resemblance to the
frugivora? Which kind has least resemblance to the
f rugivora ? Why ?

433. Man's Original Food Resources and how they have
been enlarged. — Cuvier, Owen, Huxley, and other com-
parative anatomists agree that man was originally frugiv-

1 Body measured from tip of nose to end of backbone. Mammals are the
highest vertebrates. The mother nourishes the young with milk. The
mammary glands are on the abdomen for all of the kinds of mammals except
the fourth. With the frugivora they are on the thorax.

242 ELEMENTS OF PHYSIOLOGY

orous : he ate tree fruit, both nuts and fleshy fruits. Tree
fruits contain all the four chemical classes of foods, — pro-
teids, fats, carbohydrates, and minerals. The present
sources of his food, besides the original nuts and fruits,
are flesh, grains, herbs, and he has added them to his
dietary probably in the order named above. In the warm
regions of the earth, the banana, plantain, mango, orange,
and cocoanut trees bear their luscious fruit the year
round. But the multiplication of the race and perhaps
times of drought and famine led man to use the food
stored up in the flesh of other animals which had obtained
it from grass and herbs. This necessity doubly increased
with migration to colder climates. In the frigid zones
the inhabitants live very largely on animal food. They
consume immense quantities of blubber, or the fat of
certain animals, such as the whale, the walrus, and the
seal. This kind of diet, by sustaining the necessary bodily
heat, enables these people to withstand the intense cold to
which they are subjected.

Grains in their natural state are too small and collect-
ing them was too tedious before the time of that long-for-
gotten genius who first thought of cultivating them in
order to improve them. Hunting is known to have pre-
ceded agriculture in all wild tribes. After flesh and
grains, last of all came vegetables. Fruits and grains
belong to the seed part of the plant. The coarser woody
leaves and stem and roots were probably not added to
man's food until the art of cooking was much advanced.
The degree of digestibility seems to coincide in most
persons with the order of adoption of the classes of foods
by the race. If one leads a sedentary life, or his digestion
becomes impaired, the weedy, fibrous vegetables should be
the first to be discarded from the diet, while flesh and
fruits seem to furnish the main substance for invalids even
after grains and starches prove hard to digest.

HYGIENE OF DIGESTION 243

434. Composition of Foods.

PRO-

TEIDS.

FATS.

CARBOHY-
DRATES.

WATER.

SALTS.

CELLU-
LOSE.

I. NUTS.

Pecan

10 3

70.8

Id. 3

Walnut ....

15.8

57-4

16!

•
13-

Almonds ....

23-5

53-

12.

7.8

Cocoanut ....

5.6

51-

35-

4-

II. FRUITS.

Sugar.

Peach

0.5

1.6

g-

Plum

0.5

2.O

78.

Blackberry . . .

0.5

4.0

/**•

86.

Cherry ....

0.5

10.

84.

12. C

.1 C

Fi en-

4O

1 .4

J

Banana ....

•w

5-0

20.

75-

III. ANIMAL FOOD.

Lean beef . . .

20.5

3-5

•9

75-

1.6

Fat pork ....

9.8

48.9

39-°

2-3

Smoked ham

24.8

36.5

27.8

10. 1

Whitefish . . .

18.1

2.9

78.0

I.O

Poultry ....

21.0

3-8

74.0

1.2

Oysters ....
Cow's milk .

3-5

0.5
4.0

4.0

80.0
87.0

0.7

6.0

12. C

12. 0

f.~ C

I .O

3-2

Cheese ....

33-5

24-3

36'.8

5-4

4.29

Butter ....

o-3

91.0

6.0

2.1

IV. PODS OR LEGUMES.

Starch.

3-5

24.5

2.O

C2

12. C

2.8

Peas .

21 7

I .Q

C7~7

I 2.

Peanuts ....

*» •/

29.47

49-20

1 6.2

2.77

V. GRAINS.

Wheat flour (white)

I I.O

2.0

70.3

15.0

1.7

0.3

Wheat bread . .

8.0

r.e

49.0

40.0

1.2

o-3

Oatmeal ....

12.6

5.6

63.0

15.0

3-°

1.6

Maize (corn) . .

TO.O

6.7

64.5

13-5

1.4

1.5

Rice

c.o

0.8

83.2

IO.O

o. *>

A r\

VI. VEGETABLES.

j

Potatoes ....

2.0

0.16

21.0

74.0

I.O

I.O

Cabbage ....

1.8

5.0

5.8

91.0

0.7

1.5

244 ELEMENTS OF PHYSIOLOGY

435. Nuts are the most concentrated and nutritious of all
foods. Beefsteak is three fourths water, while nuts are
less than one fourth water (see Table). Nuts are how many
times as nutritious as beefsteak ? This refers to the nut
" meats " or kernels. Nuts may be said to consist of one
half fat, one fourth proteid, and the remaining one fourth
water and mineral. The fat, unlike that of butter, oil, and
fat meat, is emulsified in nuts, and does not need to be
divided up before absorption by the lacteals in the small
intestine. Their density encourages the habit of thorough
chewing. Nuts are made up of little cells, each of which
has its proportion of proteids, fat, and dextrine, a kind of
sugar. The small boy climbs the tree and gathers the
nuts, cracks and eats them, and digests them thoroughly.
The man stays in his office, has some one else to gather
them, masticates less thoroughly, and he may find them
less digestible, especially if he always eats a full meal before
taking the nuts. Green or rancid nuts are not digestible.
Nuts should be eaten during the meal the same as meat.
They are digestible raw. Persons who usually eat nuts
after they have already eaten too much, consider them
very indigestible. They are not good for the digestion if
eaten between meals, or if not thoroughly chewed.

436. Pods, or Legumes, resemble nuts very closely in
chemical composition, but they require long and thorough
cooking. Their seed coats, or hulls, consist of cellulose or
woody fiber, which may well be removed. The hulls can
be loosened by soaking them in cold water before they are
cooked. Beans and peas have been called the lean meat
of the vegetable kingdom, and they take the place of meat
with those who discard meat (vegetarians).

437- Fruits have four important advantages : (i) Their
agreeable flavors are a natural and healthy stimulus to the
digestion. (2) They contain vegetable acids (either citric,
malic, or tartaric) that are perfect germicides, and are

HYGIENE OF DIGESTION 245

very powerful in purifying the alimentary canal. (Fruits
have almost no proteid. How does this show that a fruit
diet would starve the germs, even if the fruit acids did not
destroy them ?) (3) They contain very valuable mineral
salts that are of highest use to the blood and tissues.
(4) The carbohydrate in ripe fruits is all in the form of
levulose or fruit sugar, which is predigested starch, and is
absorbed without digestion. With these advantages, there
is the disadvantage that fruits are largely water, so that
the nutriment they contain is very scant, except in the case
of grapes, bananas, and olives.

438. The proverb that fruit is golden at breakfast, silver
at noon, and lead at night, is not true. Fruit is golden at
all times, if it is sound and ripe, and if the stomach is not
already filled with food. Fruit juices are valuable as restor-
atives .to health, since they tax the digestive organs very
little and are quickly assimilated. Since germs will not
grow in fruit juices, a fruit diet for several meals will dis-
infect the alimentary canal and ward off a "bilious" attack.
Juicy apples, pears, lemonade, orangeade, pomegraniteade,
ripe peaches, etc., are pleasanter than medicines.

439. Animal Food. Meat. — Proteid is the principal food
substance in meat. Beef contains the largest amount of
any of the common meats, and pork the least. The fat of
meat is also of great importance : fat is abundant in pork.
Meat that is salted and smoked, or dried, or prepared in
any way so that germs will not grow in it, can be kept for
a long time, but its digestibility is greatly impaired. This
is because its fibers have been hardened so that the gastric
juice cannot readily penetrate them. Meat which has much
connective tissue is tough ; the most tender and digestible
of meats consist almost wholly of muscular tissue and fat.

440- Experiments show that ordinarily one fifth of the
proteid in vegetable food passes through the intestine un-
digested and unabsorbed, and is thus wasted, while only

246 ELEMENTS OF PHYSIOLOGY

one thirtieth of the proteid in meat escapes digestion. A
pound of fat requires three times as much oxygen in its
oxidation as a pound of sugar, and therefore yields three
times the heat and energy. The digestibility of fat is in-
creased by the fact that it ferments with difficulty, while
sugar and starch ferment more easily. Meat should be
thoroughly cooked to avoid the danger of diseases from
the trichina and other parasites.

441. Milk of cows is suited for calves, and was intended
to be obtained by sucking and to be swallowed gradually.
It contains too large a proportion of proteid for infants,
and therefore water is added. The casein or proteid part
is coagulated in flakes by the rennin, and when a child
throws up coagulated milk, it does not mean that it is suf-
fering from indigestion, although it may sometimes mean
that it is being overfed. The tendency of milk to pro-
duce " biliousness " and constipation in some persons may
be explained as follows : when adults drink sweet milk
rapidly, especially toward the end of the meal, when much
acid is present in the stomach, the acid coagulates the
casein into large lumps of curd, which may seriously dis-
turb digestion, for milk was not intended to be drunk rap-
idly. Heat retards the production of acid in the gastric
juice and increases the secretion of rennin. If taken
before meals, hot and slowly, milk will agree with those
who have found it to produce indigestion. Buttermilk is
one of the most digestible of foods.

442. Cheese is a concentrated food, and is one of the
cheapest although not one of the most digestible forms of
proteid.

Does a pound of eggs contain more or less nourishment
than a pound of meat (§ 434) ? At usual prices, which
is more economical, eggs or meat (see Table, § 434) ?

443. Meat Extracts. — Researches concerning the nutri-
tive value of meat extracts, show that in none of them is a

HYGIENE OF DIGESTION 247

large quantity of food concentrated in a small bulk as the
public are led to believe. A glass of milk contains far
more nourishment than a cup of beef tea. The best way
to get the nourishment out of a steak is to eat it. The beef
extract contains but a fraction of the proteids in beef, and
all of the nitrogenous waste material allied to urea. The
most nutritious part of the beef is not soluble, but the ex-
cretory part of the meat is soluble, and this is found in the
beef tea or beef extract. This extract throws work upon
the kidneys and is harmful. The part of the beef that
has most value is thrown away in making the extract.
Many lives are no doubt annually sacrificed by starvation
through the popular faith in beef tea as a concentrated and
nourishing food. Beef tea and meat juice can be used as
flavoring agents with other food since they stimulate the
secretion of pepsin, but they should not be regarded as
real food.

444. By drying meat it can be reduced to one fourth its
weight (since it is three fourths water). Thus 100 pounds
of beef can be reduced to 25 pounds and sold in a form
useful to travelers. The meat will keep fresh as long as it
is kept dry. Water is added to the meat when it is cooked.

445. Grains. — Nearly all the starch of our food is sup-
plied by grains. They also contain from 8 to 1 5 per cent of
a proteid called gluten. The chief grains are wheat, oats,
barley, corn, rice, buckwheat. The more of gluten there is
in grain, the more gluey or sticky its flour will be. Sticky
flour will retain the bubbles of gas formed from baking-pow-
ders or by the growth of the yeast plant. Wheat has much
gluten, and its flour makes very light bread. Coarse meal
has not enough gluten to make it very sticky, and corn
bread will not rise well. Corn contains more fat than any
other grain, yellow corn containing more fat than white
corn. Rice is poorer in albumin and richer in starch than
any other grain (see Table, § 434).

248 ELEMENTS OF PHYSIOLOGY

446. Three Kinds of Flour. — There are three ways of
grinding flour: (i) Using the whole grain and the husk
which incloses the grain. This makes graham flour.
(2) By using the whole of the grain. This makes whole
wheat flour. (3) By rejecting the outer and darker portion
of the grain, thus losing part of the gluten and retaining all
of the starch. This makes the ordinary flour. Graham
flour is most stimulating to peristalsis in the canal. Its
large amount of waste matter furnishes something for the
intestine to contract upon, and thus sweep all waste matter
on and out of the body, contributing to the cleanliness
of the canal. It sometimes causes congestion in irritable
stomachs. Sometimes flour which is merely dark with dirt
is sold for graham flour. The whole wheat flour is stimu-
lating to the canal but is not irritating. Some believe that
it furnishes more of the mineral salts and bone-making and
tissue-building material than the fine flour.

447. The Cooking of Grains. — You learned that the starch
of fruit, when it ripened, .was turned to sugar. Ordinary
cooking bursts the cells of starch in the grain and begins
the transformation into dextrin, a substance intermediate
between starch and sugar. This is a great help, for the
saliva does not act upon raw starch, and the pancreatic
juice acts only slightly and after several hours' delay. Cook-
ing that amounts to little more than moistening and heating
the starch, is a disadvantage, and makes it more likely
to ferment than if eaten raw ; but thorough cooking adds
greatly to the digestibility of starch. Oatmeal, cracked
wheat, and other grain foods should be cooked at least 40
minutes.

448. How Grains may be made to resemble Fruit. — If
cooked several hours, the starch of grains is so thoroughly
dextrinized that it is changed to sugar almost instantly
when brought in contact with the saliva. Grains may be
cooked during the preceding meal and the cooking finished

HYGIENE OF DIGESTION 249

in preparing the meal at which they are to be eaten.
If oatmeal and other mushes are sticky, it shows the
presence of half-cooked starch. The yellow crust of
bread will not stick together because the starch has been
changed into the last stage of dextrin, called yellow dex-
trin. Rice and oatmeal may be first browned in the
oven and afterward steamed. Toast and brown crust
are almost as digestible as ripe fruit and are given to
invalids.

449. Cellulose has the same chemical composition as
starch. It forms the cell walls and woody fibers of plants,
and is hardly digested at all by man ; hence, starch requires
cooking to burst the cellulose envelopes of the starch
grains. Cellulose and water are the chief constituents of
grass, and of greens, cabbage, and other fibrous vegetables.
It forms the fibers in watermelons, which also contain cane
sugar, the sweetest of the sugars. The woody skins of beans
and peas are cellulose. Hence, many find the legumes
more digestible in a puree, or cooked with the skins re-
moved. Cellulose is the natural stimulant to peristalsis
and activity of the canal. Cattle digest cellulose, and with
them it takes the place of starch.

450. Vegetables. — Root vegetables and tubers, such as
potatoes, sweet potatoes, and turnips, contain a small per-
centage of starch. But vegetables in general consist almost
entirely of water and woody fiber (cellulose). This is
especially true of green vegetables, or those which consist
of the leafy part of the plant. But green vegetables con-
tain nucleo-albumin, or iron-bearing albumin, which is of
great value to the blood and tissues. This form of albu-
min is easily destroyed in the intestine before it reaches
the blood, if fermentation takes place. As some leafy
vegetables are more likely to ferment if cooked, there is an
advantage in eating them raw. Iron and valuable mineral
salts are thus obtained.

250 ELEMENTS OF PHYSIOLOGY

451. The nostrum venders who shamelessly advertise
their iron tonics "to enrich the blood" are only attempt-
ing to prey upon the ignorant. The magical power of the
sun's rays can turn iron into food. The brown color of
the grain, the red cheek of the tomato, strawberry, and
peach are due to iron, and iron in this form will enrich
the blood. For a student to learn that iron colors the red
corpuscles, may be of some value, but if the only purpose
the knowledge serves is to aid in entrapping him into be-
lieving that the patent-medicine man makes a valuable
blood tonic out of rusty nails and alcohol, his method of
study has not cultivated his judgment, nor cured him of
the natural propensity to jump at conclusions.

452. Leonard Hill, Professor of Physiology in the Royal
College of Surgeons, says : " In these days of advertise-
ments it is necessary to strongly warn the reader against
the lies of the trader and the quack. The method of
fortune-making by advertisement is to sell a well-known
and cheap article at a dear price, under a new name, with
a flavor added, and the vaunted pills, when submitted to
analysis in chemical laboratories, are found to consist of
aloes, salts, or other common drugs, which the quack buys
for a few pence a pound, and sells for a shilling an ounce.
Most of the minor ailments are produced by errors in
diet and lack of healthy exercise. These ailments are
relieved temporarily by a purge, and the public are per-
suaded thus to buy fruit salt or pills for a shilling, when
the required article, aloes or Epsom salts, can be obtained
for a penny. Among the numberless quack medicines
sold for nervous exhaustion, many are altogether value-
less, and sometimes contain stimulants, such as alcohol
or coca. Nervous exhaustion can be cured, not by drugs,
but by changing the habits of life. Bicycling, bathing,
and gymnastic exercises are worth infinitely more than all
the drugs in the world. Errors in living can be atoned for,

HYGIENE OF DIGESTION

not by the taking of medicines, but by learning the art of
living, and of this lesson, spare diet, hard work, and exer-
cise form the first and last page.

" In countries other than England the patent-medicine
venders are forced to publish the ingredients of their con-
coctions, and the governments warn the public and state
the nature and exact price of the ingredients. In England
the people are allowed to be fooled and defrauded of mil-
lions of money by quacks, while the government, to its
disgrace, does nothing to protect the poor, weak, and
the ignorant from them."

453. Is England the only country in which this fraud-
ulent business is allowed to flourish unchecked ? The
formula should be required by law to be printed upon
the bottle. Most patent medicines in large bottles, such
as sarsaparillas, bitters, etc., contain about the same pro-
portion of alcohol as brandy contains. Even in grogshops
the character of the drink that is being sold is not entirely
misrepresented to the customer.

454. An Error of Vegetarians. — Those with whom meat
does not agree, or who for humane scruples, or other
causes, adopt a vegetarian diet, sometimes fall into serious
error. If fruits and nuts are not freely used, but the diet
is confined to grains and green vegetables, a large excess
of starch is consumed, and the diet is very bulky, in spite
of the fact that it is greatly lacking in fat and proteid.
Persons who do not eat meat should replace the proteid of
meat with that of nuts, cheese, beans, and peas, and employ
fat in the form of nuts, cream, milk, eggs, and butter.

455. Many millions of people, the most populous nations
of the earth, eat no meat. The inhabitants of the countries
largely vegetarian in diet, as India, China, etc., constitute
a majority of the human race. It may be possible that
they would be a more vigorous people if they lived upon
a more varied diet. People of warm countries flourish on

252 ELEMENTS OF PHYSIOLOGY

a vegetarian diet ; it is also possible to do so in a temperate
climate, but it is hardly possible in the frigid zone. An
Eskimo will eat fifteen pounds of walrus fat in a day.
Too much meat in the diet affects students and sedentary
individuals more injuriously than it does muscle workers.

456. Should the Diet be Bulky or Concentrated ? — The
way this question is answered will determine whether
graham or white flour is better, whether the skins of beans
and peas and fruits should be removed, whether one should
eat coarse vegetables, such as cabbage, greens, celery. It
is probable that the true answer is that sedentary persons
with weak peristalsis of the stomach should not eat much
woody material as it causes the food to remain too long in
the stomach before it is reduced to chyme, while persons
whose business requires muscular activity and whose ali-
mentary canal possesses a more vigorous peristalsis, will
find a bulky food preferable.

457. If, some hours after eating boiled cabbage, you
could still taste it, or another could detect the odor of it on
your breath, what inference might be drawn? If greens
were added to the usual dinner, and you had a feeling of
heaviness or dullness after dinner, what would you infer?
What would be the conclusion if you felt more vigorous
than usual? If you had fallen into the bad habit of
taking the feverish haste of business to the dinner table
with you, but on one day you " took things easy " at dinner,
as well-bred people should, eating very leisurely, and you
had a feeling of unusual lightness and energy in the
evening, what would you infer?

458. Should a Person drink at Meals? — Slow, careful
eaters, whose throats refuse to receive anything that is not
thoroughly chewed and mixed with saliva, should not drink
while eating, as it would dilute the digestive fluids already
abundant. But those who eat rapidly or do not chew
thoroughly, often find that some liquid at meals aids

HYGIENE OF DIGESTION 253

digestion, for with this manner of eating, the natural
secretions are insufficient. Should the liquid be sipped
with each mouthful, or should it.be taken at intervals and
when the mouth is empty ? Which method would have
less effect in decreasing the flow of saliva ? Which method
would be more likely to increase the tendency to bolt the
food down ?

459. Individual Wants. — The student readily sees that
the question of individual needs is of importance. There
is truth in the old adage, " What is one man's meat is -an-
other man's poison." No cast-iron rules can be laid down
for any one's life. Common sense can never be dispensed
with. Persons with moderate powers of observation find
by experience what is best, and they should have will
power enough to adhere to what they find is best for
them, although opposite ideas may be presented to them
as the only correct way, by persons of narrow views.
What is enough for one is a surplus for another. Sex,
age, occupation, and heredity, each has its influence on
diet. The wear and tear of an active body requires a class
of food which to one of sedentary occupation would be
a burden. Exercise lights the fire that burns up the
refuse of the body, and thus it increases the appetite and
strengthens the digestion.

460. Indigestion in Sound Digestive Organs. — If a person
confines himself closely with brain work and takes no exer-
cise whatever, he may not digest his food well, but he need
not think his digestive organs unsound, and begin dieting
himself. He should take more exercise, and by better
habits of life stir up his circulation, use the food stored in
the cells, and they will become hungry for more, and diges-
tion will be perfect. There is a saying, " You can lead a
horse to water, but you can't make him drink." So you
may put food in the alimentary canal, but you cannot make
the cells assimilate it? although, by the use of much pepper

254 ELEMENTS OF PHYSIOLOGY

and condiments, you may have aroused an appetite for it.
Such food may not be digested, but it does not mean that
the digestion is weak, it means only that too much food
and too many condiments have been used.

461. Two Ways out of a Difficulty. — Exercise is the
best way out of digestive troubles ; yet, if a student or office
man is under the delusion that he "just simply has not
time " to take plenty of exercise, he may partly meet the
difficulty and keep his brain clear by an abstemious diet.
Many a plow boy has gone to college, and failing to take up
athletics or to perform any manual labor, yet has continued
to eat the same quantity of food which before sustained
him in his labor, but which now only clogs the organs and
stupefies the brain. Thus his work as a student does not
accomplish half that it should accomplish.

462. Cooking. — Meat should be roasted by putting it into
a hot oven at first, to form a crust to keep in the juices, then
lowering the temperature of the oven to prevent drying out
and hardening. When broiling meat, it should be turned
over every ten seconds to send the juices back and prevent
their escape, thus broiling the meat in the heat of its own
juices. Tender meat should be broiled, but tough meat is
often better fried. Grease for frying should be boiling hot
when the meat is put in, to form a crust and prevent any of
the grease from soaking in. Fried meat that is grease-soaked
is the most unhealthful of all cooked meat. Meat should
not be salted until after it has been cooked, for salt draws
the juices out.

463. Bread is best if made of whole-wheat flour. It
should be cooked in a slow oven, so that the inside of the
loaf may be well baked. The loaves should be made small
and not touching, so that there may be much crust. Crust
(i) cleans the teeth like a brush and makes them healthy
from use ; (2) it increases flow of saliva by its dryness and
the longer chewing required ; (3) it is more easily digested

HYGIENE OF DIGESTION 2$$

than the crumb, or white portion, as it resembles sugar. Bea-
ten breadis the most digestible, like the hoe cake and johnny-
cake and other unleavened breads. Yeast bread comes next
in digestibility. Baking powders, if they contain alum,
and soda, if not thoroughly neutralized by sour buttermilk,
are injurious even to the healthy. It is quite possible
that the depression and nervousness caused by innutrition
from trying to live on such abominations as soda biscuit and
grease-soaked food, are often the forerunners of drunken-
ness and other misfortunes that a small amount of intelli-
gence in the kitchen would have prevented.

464. Yeast belongs to the class of plants called fungi,
which can live in darkness, and have neither leaves nor blos-
som. Most plants get nourishment from the soil, air, and
water, but yeast and other fungi derive their sustenance
from vegetable or animal matter in process of decomposi-
tion. Yeast plants are microscopic cells of oval shape, and,
like other plants, require food in liquid form. They can-
not absorb dry or solid food. Their most suitable food is
sugar. The flour of wheat contains starch, a small amount
of which is converted into sugar by the diastase which lies
next the bran. Yeast grows best at a temperature of from
70° to 80°. A slow growth at a lower temperature favors
the development of other micro-organisms, which make the
yeast unhealthy and produce bad flavors. With a high tem-
perature its growth is rapid and of extremely short duration.
Fermentation may go through several stages ; in the first
stage, or alcoholic fermentation, the yeast decomposes the
sugar, splitting it into alcohol and carbon dioxid gas.
This is the stage for bread-making, the gas causing the
bread to rise. In the second stage, or vinegar fermentation,
alcohol is changed to acetic acid — the acid in vinegar.
Hard wheat has more gluten than other wheat, and the
bubbles formed in its flour will not break easily. Why
does bread from such wheat rise well ? Why is bread set

256 ELEMENTS OF PHYSIOLOGY

in a warm place to rise ? Why does it "fall" if left to stand
too long? Under what conditions does bread made from
yeast become sour ? Why does bread set to rise in a cold
place sometimes have a bad flavor ?

465. Irish potatoes, to become mealy instead of soggy,
should be put into boiling water, and, after they are cooked,
the water should be poured off, and the pot should be set
on the back of the stove for the potatoes to dry. Roasting
them in the oven with their skins on also retains their flavor
and makes them mealy.

466. Cucumbers are as digestible as apples if eaten raw
and when sweet. Pickles are' absolutely indigestible, and
are treated as foreign substances. Onions are better if
cooked, to drive off the acrid, irritating oil. Raw cabbage,
which is water and woody fiber, is treated by the stomach
as a foreign substance, and sent promptly to the intestine;
but the stomach attempts to digest boiled cabbage, and it
remains there several hours. The skins of peanuts, after
boiling water has been poured over them for a moment, can
be easily removed. If then allowed to simmer on the stove
for hours, until they can be easily pressed through a col-
lander, they form a nutritious and palatable food, with the
addition of a little salt. Raw and roasted peanuts are not
easy to digest. Eggs should be cooked by placing them in
boiling water and taking the pot off the stove. They cook
while the water is cooling, and the albumen is jellied but not
hardened.

467. Is Alcohol a Food? — When alcohol is taken, about
ninety-five per cent of it is oxidized and changed into car-
bon dioxid and water. This was found out many years
ago and raised the question as to whether it should be
classed as a food. Investigations were made, and the re-
sult was that alcohol was classed with the poisons and not
as a food. The question has been reopened several times
in the last half-century, but always with the same result.

HYGIENE OF DIGESTION

Scientific men generally continue to classify it as a poison
and not as a food. Morphine, mushroom poison, strych-
nine, and other dangerous poisons are oxidized in the
body and yield up their energy, yet they are recognized
as poisons. A substance cannot be classified as a food
simply because it is oxidized in the body.

468. Leading scientists define a food as follows : A food
is a substance of such a nature that, when absorbed into the
blood, it nourishes the body without injuring it.

469. Sugar is a food but a solution of sugar can undergo
a change caused by the growth of millions of yeast plants
and the food is lost. The change is called fermentation,
and alcohol is one of the poisonous products of this process
of decay or fermentation.

The condition of the body after it has oxidized alcohol
is quite different from its condition after it has oxidized
sugar or bread. Benzine is very easily oxidized. If
poured upon the fire of a locomotive, it would make the
water boil so rapidly that there would be danger of strain-
ing or bursting the boiler. It would burn so rapidly as
almost to make an explosion, and a very large part of the
heat caused by the oxidation would be lost. A stove
needs a slower burning substance than gunpowder or ben-
zine. A locomotive needs a slow-burning fuel which
will develop heat at such a rate that it will be possible to
utilize it. The body needs even slower burning substances
than the locomotive, such as sugar, starch, and fat ; not a
more rapidly burning substance, such as alcohol, which in
burning will weaken the tissues and shock and injure the
delicate cells of the one who drinks it. In the chapter on
the blood it was learned that alcohol does not even cause a
gain of heat in the end, since the paralysis of the capillaries
resulting from a drink, causes the warmth to be taken to
the surface and escape, so that the body is cooler than
before the drink.

258 ELEMENTS OF PHYSIOLOGY

470. True food does not burn in the blood ; it is stored
in the cells in the form of very unstable compounds.
These compounds break down under the stimulus of oxy-
gen and the nerve current, and set free energy. The cells
of the nerves and muscles correspond to the furnace and
steam chest of the engine. Suppose, instead of pouring
benzine into the furnace, you burned it in .the cab or the
smokestack. Do you think it would increase the power
of the locomotive ? Alcohol is not stored in the cells, nor
does it enter into combination to form the energy com-
pound, the breaking down of which sets free the energy
stored up. Alcohol burns quickly after entering the
body ; a large part of it, indeed, never gets beyond the
liver, and is burnt in this long suffering organ. But some
of it gets into the general circulation, and is distributed
throughout the body, irritating the nerve cells and poison-
ing them and every other tissue.

471. Does Alcohol warm the Body as well as a Coat ? —
It may occur to a user of alcohol to say, "It certainly
gives warmth, for it burns ; so it is of some benefit. It is
equal to a good overcoat, if it is not food, and like the
overcoat, it may save the burning of some of the fuel-food,
sugar and fat." Benzine may tear up the machinery, but
it certainly gives heat. But suppose you put most of the
benzine in the cab just before the furnace door. It will
use up the oxygen and furnish carbon dioxid in the draught
to the furnace, instead of fresh air. Will this make the
fire burn brighter, or will it smother it ? This is exactly
what alcohol does ; it uses up the oxygen supplied to the
blood by the ever-faithful lungs, and the blood carries
carbon dioxid to the brain, muscles, and other tissues.
An overcoat does not smother the tissues by using up the
oxygen they need. Thus it happens that the drinker's
nerves become deadened, his faculties dulled, his mus-
cles weak and unsteady. If he drinks much at a time, he

HYGIENE OF DIGESTION

falls into a profound stupor — he is " dead drunk." Thus
the heat from the oxidation of the alcohol prevents the
true tissue activity which is necessary for the life pro-
cesses, and burdens the liver with an unnecessary activity
in destroying the poisons. The poison, in the meanwhile,
has paralyzed the arterial walls and allowed the capillaries
to become flushed, and the warmth of the blood rapidly
escapes through the skin. By using up the oxygen,
it checks the production of heat in the usual way, while
the heat resulting from its own oxidation is soon lost to
the body, and much more of the bodily heat besides.

472. One ounce of alcohol requires two ounces of oxy-
gen to oxidize it. The lungs furnish twenty-four ounces
of oxygen daily. How many hours will it take the lungs
to supply oxygen enough to oxidize one ounce of alcohol ?
Three drinks of whisky contain one ounce of alcohol.
How many drinks would be necessary to use up a day's
supply of oxygen ? A man would probably die long
before he had drunk that quantity.

473. The Secret of the Influence of Alcohol. — It is a fact
that we are clearly conscious only of the energy that we
are exerting, and not of the energy that is stored up in our
bodies. When alcohol is first taken, the cells treat it as an
intruder, and the activity excited by the attempt to expel it
from the body causes the man to think the alcohol is giv-
ing him strength, when it is only taking it away. It de-
ludes the drinker into thinking that he is strong, though
before the drink he had been feeling weak ; warm, though
he had been feeling cold ; it makes him careless, when he
had been careworn ; confident, when he had been feeling
timid. These are pleasant effects. But the later effects
of headache and depression and gloom, worse than before,
he does not attribute to alcohol, since they are not so
closely associated in time with the drinking. He does not
remember the crazy or idiotic scenes that were enacted when

260 ELEMENTS OF PHYSIOLOGY

he was wholly under its influence, the wild or maudlin talk,
the loss of all self-control, the quarrel with the best friend,
and the abuse of wife and children, and afterward the
drunken stupor. If he did recognize these effects, he would
stop the use of the poison. If remembered at all, they are
only as an unreal dream that is not a part of his life. A
man once fell into a fire while intoxicated, and just as fall-
ing into cold water will sometimes sober a man, the pain
and danger brought him to his senses ; he realized what
alcohol was doing for him and never drank again. The
various inebriate cures, so called, are founded on the prin-
ciple of making the patient disgusted with alcohol by
secretly adding some nauseating drug to the drink, thus
giving the man the belief that alcohol is making him sick.
As long as the belief in the repulsiveness of its effects re-
mains, the man can abstain ; but most drunkards relapse
into their old ways. Their bodies have been already
ruined, and they have no strength of will left. When
they once drink again, the association of alcohol with
the agreeable emotions previously mentioned is renewed
and the power of the habit reasserts itself.

474. Time for Eating. — Different nations have various
habits of eating. The number of meals varies from two
to five, or even eight, meals daily. Such facts show the
adaptability of the stomach to different habits. It is an
organ which readily forms habits, and is greatly benefited
by regularity. If a person avoids disturbing the stomach
between meals and allows it needed rest, both appetite
and digestion are promoted. Three meals a day seem
to be needed, especially by hard workers. The Greeks
ate two meals a day, and developed the most beautiful and
perfect bodies in the world, as shown by the statues left
by them.

475. Very active exercise tends to hinder the work of the
stomach, but facilitates that of the intestines. For a half-

HYGIENE OF DIGESTION 26l

hour after a full meal, hard work of every kind should be
avoided, but hard work an hour or two later will aid diges-
tion. The arrangement of the meals must take into ac-
count the other habits of the individual. For example, if
three meals are eaten in twenty-four hours, the last ought
to be the lightest ; but, as business is transacted in large
cities, a business man can hardly find time for a hearty
meal in the middle of the day. Hence he does right in
eating a lunch at noon, and having the heartiest meal come
in the evening, when the day's labor is over and there is
time to relax. If he takes the principal meal in the latter
part of the day, he should not eat very heartily the next
morning or during business hours ; to do so would
surfeit the system. Late suppers should not be eaten, as
they prevent sound sleep. The lower animals may lie
down in the shade and sleep after eating, but it is only for
a short nap. A nap of ten minutes, just long enough to
bring about relaxation, is often of benefit after a meal.
During sleep the heart beats less frequently and with less
force ; the lungs breathe less freely ; the brain ceases its
activities ; the muscles relax and become motionless ; peri-
stalsis and secretion in the alimentary canal become slow,
and the digestive organs should have rest If a person is
troubled with a too great flow of blood to the brain, some
light, digestible article of food taken just before retiring
may bring sleep ; but it should be taken simply to regu-
late the circulation, and should be so digestible as to give
little work to the stomach. A farmer will do a better after-
noon's work if he will rest for half an hour after the noon
meal.

476. The rule that every individual must be a law unto
himself may be abused by those who consult their appe-
tites alone without reference to their common sense. If
we believe that regularity in eating is desirable, the stom-
ach and appetite can be trained to it, although if one is

262 ELEMENTS OF PHYSIOLOGY

used to eating at all times and between meals, the desire
to do so may remain for a time. An appetite for whisky
is an acquired one, and it is not an evidence of a normal
and healthy demand. Emaciated and half-starved persons
may suffer from want of appetite, but it may be a sign that
they should increase the activity of other organs, as the
muscles, not that they should eat insufficient food.

477. A good and healthy appetite comes from the ex-
penditure of energy and rebuilding of the tissues, and a
person with such an appetite enjoys best the simple foods
that will best give energy and build tissue. The best
pleasures of eating are for those who have appetites of
this kind, not for the epicure or glutton. This is only one
example of the general truth that mere pleasure seekers
do not have the best pleasures ; but they enjoy life best
whose living is complete, all the duties and pleasures of
life being given their place, and none allowed to usurp.

478. Subject for Debate. —Resolved, That the evils result-
ing from bad food and improper eating in the dining room
(aside from the inestimable benefits of food) have been as
great a curse to the human race as the evils resulting from
the barroom.

479. THOUGHT LESSON. Clothing. The Head. — The
position and extent of bald spots show that baldness is

caused by . The best kind of a hat is [stiff or soft ?

light or heavy ? ventilated by holes or air-tight ?] and worn
[as much or as little ?] as possible.

The Neck. — The neck is very [flexible or inflexible ?]
It is healthier [with or without ?] covering. Stiff or high
neck clothing [destroys or preserves ?] its beautiful curves,
and makes the neck [skinny or full ?] and makes one
[more or less ?] apt to take cold.

The Trunk. — The most flexible portion of the trunk is

the . I find by measuring with a tape line that the

circumference of my chest is inches more with the

HYGIENE OF DIGESTION 263

lungs expanded than when they are contracted. This is
called chest expansion.

My waist expansion is inches. If I have my

clothing cut to fit the larger waist measure, and support it

by the waist, its weight will cause it to when the waist

contracts in breathing. If cut to fit the smaller waist

measure, the cannot and my breathing will be

. The [shoulder or waist ?] is made mostly of tough

bone and muscle, it contains no delicate vital organs, it does

not expand or contract ; it is horizontal while the is

vertical. Therefore the is better for a support to the

clothing than the . The seven vital organs at the

waist are the st , 1 , sp , two k , p , and

a portion of the large .

The weight of the clothing on the shoulders may flatten
the chest and draw the shoulders forward if the weight is
supported over the front of the chest. Therefore the weight
should fall mostly at the sides. (The buttons for men's
suspenders should be at the sides, just over the pockets.)

The " Health " corsets, and " Good Sense " health waists,
with straps at shoulders, are misnamed, for as worn the
straps are loose and useless. No clothing can be supported
from the shoulders unless it is loose enough to slip down at
the waist when unfastened or loosened at the shoulders.

Among the first five of acquaintances thirty years old

or older, of whom I happen to think, are sickly. Of

five gentlemen, are sickly.

APPLIED PHYSIOLOGY
EXERCISE I

1 . How do you explain the difference in the way a dog eats meat
and a horse eats grain ? (Compare with Question 8.)

2. Clothing and shelter for man or beast economize what kind of
food?

264 ELEMENTS OF PHYSIOLOGY

3. Why does wheat bread rise better than corn bread ?

4. Why is corn bread one of the most fattening of grain foods ?

5. Why is it that you can tell best about the digestibility of bread
while you are slicing it ?

6. What kind of persons would not find it well to take a long walk
before breakfast ?

7. Why are late suppers unhealthful (§ 475)?

8. Why should bread remain longer in the mouth than meat?

9. In snowballing what is the appearance of the hands when they
itch from cold ? Why is it that ice water does not satisfy the thirst,
but often produces a craving to drink more water ?

10. Why is it more difficult to swallow a small pill than a large one
(§373)? "

EXERCISE II

11. When is hunger a safe guide ?

12. Why does not fat meat taste as well in summer as in winter ?

13. Name organs which receive more benefit from the blood than
they give to it.

14. Name organs which give greater benefits to the blood than they
receive from it.

15. Why should pork be thoroughly cooked ?

1 6. What necessary step in preparing salt meat to be cooked lessens
its nutrutive value ?

17. Should biscuits, having a yellow tint or dark spots due to soda,
be eaten or thrown away ?

1 8. Why, during an epidemic, are those who have used alcohol as a
beverage, usually the first to be attacked ?

19. What is the effect of alcohol upon albuminous substances ?

20. Explain how it is that when people speak of an inactive liver
they usually mean an overworked one (§§ 407, 408).

EXERCISE III

21. How does the possession of a gall bladder furnish evidence that
man should have meal times and not eat at all times ?

22. Who attains greater success in life and true happiness, the man
who makes millions of dollars but loses his health by close application
to money making, and has to live on gruels and soups, and does not
have sound sleep, or the man who makes a living and no more,
sleeps soundly, enjoys his food, and has strong nerves ? Which do

HYGIENE OF DIGESTION 26$

you regard as a truly successful man ? Which does public opinion re-
gard as more successful ?

23. Do you buy more wood (cellulose) when you buy beans or when
you buy nuts (§ 434) ?

24. Do you buy more water when you buy bread or when you buy
meat ?

25. Which is true, the original saying: " Stuff a cold, and you will
have to starve a fever," or the modern way of stating it ?

26. Why is soda sometimes good medicine to neutralize a sour
stomach, and very bad for digestion if eaten in bread (§§ 91, 377)?

27. What advantage in digestibility may a hot biscuit have over a
loaf of stale bread ? Vice versa ?

28. Some physiologists hold that the eating of much meat causes an
irritable temper. Does your observation of others or your personal
experience confirm or disprove this ?

29. Why do people who live in overheated rooms often have poor
appetites ?

30. Why may the taking of prepared pepsin weaken the stomach ?

31. Why is there often an outbreak of colds when a warm moist spell
of weather succeeds several weeks of cold dry weather (§§ 6, 587) ?

32. Explain how the stomach may be weakened by the eating of
"predigested foods.

NOTES

1. What the Carpenter said. — "You literary fellows talk about the
breakfast question. All you need to do is to get out and do some
work. Use your hands. Take some exercise like I do, and you can
eat anything. You sit there all day cooped up in your office and write,
write, write. You cannot enjoy food or sleep as long as you do that.
Come out here and shove the jack-plane an hour or two ; that will give
you an appetite. Let me get you at one end of this cross-cut saw at six
o'clock in the morning, and I will settle the breakfast question for you
in a hurry. You will have no need of patent cereals or fancy foods in
pasteboard boxes."

2. Cotton Seed as a Food. — The American Analyst says : " Two
thirds of the olive oil sold in the markets of the world is born in the
cotton fields of the Southern States."

Dr. Allan McLane Hamilton says : " I consider one of the most
healthful articles of diet that we can possibly have, to be cotton-seed oil.
It is one of the best fats, and is much more healthful than lard."

Dr. R. O. Beard, a professor in the College of Medicine, Minneapolis,

266 ELEMENTS OF PHYSIOLOGY

Minn., says : " Cotton-seed oil is a wholesome, nutritious vegetable oil
which delicate stomachs bear without injury."

3. The Mouth shirks Duty at the Expense of the Stomach. — The
average chronic dyspeptic needs to eat pure food and avoid soft and
sloppy food. Why ? Because when the food is in the form of slops it
is well lubricated, and when taken into the mouth it goes down before
you can say "Jack Robinson," and the food has not had saliva mixed with
it and thus escapes mouth digestion. Now mouth digestion is just as
necessary as stomach and intestinal digestion ; the mouth must do its
work properly in order that the other steps in the digestive process may
be well performed. The process of digestion is like setting up a long
row of bricks, each being a little space from the other, so that when the
first brick is tipped it strikes the next brick and knocks it down, and
that strikes the next, and so on till all the bricks are down. Mouth
digestion prepares for stomach digestion. — Good Health.

4. Sick Headache, and How to Avoid It. — Sick headache means
germs and foul matter in the alimentary canal, especially the stomach.
These attacks are always preceded by well-marked symptoms ; by noting
and profiting by these, and by using common-sense treatment, no one
need agonize through such painful experiences at any time.

Among the warning symptoms are dullness, sleepiness after eating,
floating specks before the eyes, a coated tongue, and often constipation.
Sometimes there is a voracious appetite. In fact, large quantities of
food are taken into the body and retained there, and but little is elimi-
nated. The natural result is that there is stagnation from clogging up
with spoiled food and retained waste matter. The poisons produced are
carried by the circulation to all parts of the body. Much blood natu-
rally goes to the head, and with it a large amount of poison.

Common sense would say that when the source of a disorder is known
the proper thing would be to remove it ; instead of giving some opiate
to quiet the symptoms, which are only the wise protest of the bodily
organs against abuse, it would be more rational to relieve them by
removing the unhealthy matter from the stomach and bowels ; or if the
treatment is begun in time, all that may be needed is a fast, or a fruit
diet for twenty-four hours, and free water drinking, to give the sys-
tem time to dispose of the excess of waste matter.

— J. H. KELLOGG, M.D.

5. Pawlow, an eminent Russian medical authority, made a kind of
window in a dog's stomach, so that he could look in and see what was
going on. He found that when he brought savory food to the dog and
placed it before his nose and eyes and didn't let him eat it or taste of it,
by looking into his stomach he could see the gastric juice trickling down

HYGIENE OF DIGESTION 267

the walls of the stomach ; he could see that the stomach was getting
ready to digest that food. The flavor of the food had given notice that
it was coming, but it didn't come, so the poor stomach was disap-
pointed. In like manner your mouth will water for grapes which you
see and which are out of your reach, and so a boy's mouth will water
for a pie which is placed upon a top shelf or somewhere where he can
see it, and it is out of his reach. Now when this dog didn't see the
food brought to him and didn't smell of it, nor get a chance to chew it,
and it was surreptitiously slipped into his stomach, there was no flow
of gastric juice, and no digestion. Now if you eat food .too fast, or in
the form of mushes, for example, it slips down into the stomach before
the stomach has notice of its coming, and so has not made preparation
for the disposal of the food. The nose does not smell the food, and
the mouth does not chew and taste the food sufficiently to excite the
stomach to set up the general process of digestion. Numerous simi-
lar facts might be presented, showing very clearly the close relation
existing between the various digestive processes and intellectual states.
Long observation and experience prove that it is far better for a per-
son to eat what is set before him, asking no questions, either for con-
science' sake or the stomach's sake, than to take food in an anxious
and worried state of mind, questioning or doubting the nutritive value
of the food to be eaten. Many a chronic dyspeptic maintains his dis-
order by keeping his stomach in a sort of "stage fright," through the
concentration of his attention upon this portion of his anatomy during
the whole digestive process. — Good Health.

CHAPTER XV
STIMULANTS AND NARCOTICS

480. In the year 1881 Dr. Hammond, a New York phy-
sician, made the assertion that a forty days' fast was a
physical impossibility. This led Dr. Tanner, a Minnesota
physician, to attempt such a feat. He arrived in New York
weighing 184 pounds. He was six weeks making arrange-
ments for his fast, and when he began his experiment, his
weight was 157^ pounds. He weighed \2\\ pounds on
the day his fast ended. He had therefore lost 36 pounds
since his fast began. The first thing he ate to break his
fast was a watermelon, swallowing only the juice. Dr.
Hammond came out in a card in the New York papers de-
claring that he believed the fast had been fairly conducted.

481. Succi, an Italian, successfully accomplished a fast
of 50 days in London, being likewise constantly watched to
make sure of his fasting. There is reported, on good au-
thority a case of an insane person who suddenly became
possessed by the idea of taking no food, and who took 60
days to starve himself to death. Long fasts are a great in-
jury to the body, no doubt, but what can we learn from
such experiences ? Certainly it shows the wisdom with
which we are made, certainly that our physical organization
is very provident.

482. Once some miners were shut in by caving of part
of the mine. But unlike the cases mentioned above they
were without water as well as food.. When, by digging,
the rescuers reached them, seven days after, several
were still found alive, although most of them had suc-

268

STIMULANTS AND NARCOTICS 269

cumbed. The miners, no doubt, had nourishment in their
bodies for some weeks more of life, but the necessary sol-
vent in the form of water was lacking to dissolve it and
bring it within the reach of the cells most needing it.

483. A Fact of Immense Importance. — This fact concern-
ing the amount of nourishment stored in the human body
(in one case a two months' supply !) is one of the most
stupendous facts with which the science of physiology has
to deal, and it should be borne in mind, or we may greatly
deceive ourselves about some very simple matters.

484. Foolhardiness. — Did you ever get so tired that you
had to give up and stop, however much you would have liked
to continue at work or play ? To rest was the wise thing to
do. Now, although you learned from physiology how much
energy you have stored up within your frame, you should not
on that account, be tempted to go on until you almost break
down. Probably you know people who are conceited about
their bodies and say they are made of cast iron ; nothing
can hurt them. Did you ever know anybody who was con-
ceited about his mind and thought he was very bright ?
It is just as foolish to be conceited about the body.

485. A Blessing in Disguise. — It is a very wise arrange-
ment that under ordinary conditions we cannot get at the
surplus energy we have. We are compelled to be provi-
dent, as it were ; yet stimulants and narcotics, by irritating
the cells, will cause them to expend some of this reserve
energy ; they will enable man to get at this precious store
which he should save for emergencies, such as a spell of
sickness when he cannot digest food, or when he is making
some mighty effort. This reserve energy will enable him to
undergo some trying ordeal successfully.

Did you ever know of a weak sick man who had eaten
very little for weeks, yet was so powerful that it took
several strong men to hold him ? This sometimes hap-
pens in the case of sick men who are delirious and

2/0 ELEMENTS OF PHYSIOLOGY

crazed with pain and with the poisons formed in their
bodies during illness. But the delirious mania often uses up
the little energy left and costs people their lives.

486. The Meaning of Fatigue, the Blues, etc. — Suppose
you are tired or worked down. The fatigue depresses you,
and you feel discouraged. What ought you to do ? Why,
rest, of course, and you will soon feel all right again.
This seems very simple, yet some people will not do this
way, but take an alcoholic beverage or tobacco, which
will keep them from feeling tired when they are tired.
If you have been working hard preparing for examinations,
or gathering hay, or in attending to some important busi-
ness, or have been under the excitement of some pleasure
trip, and feel blue and worn out, then bear the result like
a man, or like a true boy or girl, as the case may be.
Giving up for a while, or " toughing it out " with the blues,
or losing a little time from business, will not hurt you but
will make you strong, while a stimulant will leave you less
of a man than before.

487. There is only one source of energy for man's body,
and that is the union of food and oxygen. He must get
his energy from the same source that the engine does, and
that is from his food, which serves as fuel, and the oxygen
that burns it. The millions of little workers, the cells, will
store up food within themselves and get rid of the ashes
and refuse, and the pure, sound body will be ready for
work again.

488. Alcohol is a Whip or a Spur. — It is to get strength
out of a man, not to put it in. When a person feels
that he is all tired out and his nerves are weak, and
takes a stimulant, it is the same as if, when his horse shows
signs of breaking down, he should lash him with a keen
whip, or pierce him with a sharp spur, instead of letting
him rest. Many a fine horse under the sting of the whip
has been spoiled in a few hours, and many a man has been

STIMULANTS AND NARCOTICS 2? I

physically ruined for life by overworking, goaded on by
alcohol, during one season of business rush.

489. How Stimulants arouse Energy. — You remember
those wonderful little one-celled animals, the amebas. If
poison is brought near, they will try to escape it. They also
throw out the impurities generated by their own life pro-
cesses. If anything touches one roughly, it will draw back
from the danger. Likewise, if a man takes poison, such
as alcohol or tobacco, into his body, the cells will try to
throw it off. The heart, although it may be already tired,
goes to thumping anew, secretions are poured out by
the cells to dilute and weaken the poison, and the great
activity excited diverts the man from noticing his fatigue,
and makes him think the poison has given him renewed
strength. It is the same as if he thought the whip instead
of the oats gave the horse strength. The horse, like the
cells of the body, is only trying to avoid something harm-
ful, and like them, he uses up his strength in so doing.
After a while he will be very stiff and tired. There is no
artificial stimulant that does not cause a reaction. The
stronger the stimulant, the worse the poison. Strychnine
is one of the deadliest poisons known, and also one of the
most powerful stimulants. If an animal is given strych-
nine, its nerve tissue is sometimes reduced to such an
irritable condition that a loud sound, or merely touching
any part of it, will throw every muscle of its body into a
spasm.

490. Natural Stimulants do not cause depression. The
chief natural stimulants are cold air, sunlight, pure air,
physical exercise, interest, joy, and other emotions. A deep
breath of pure air is a better stimulus than a glass of beer ;
climbing a hill or sawing -a log of wood will make the blood
flow faster than alcohol ; a pleasant talk with a friend is a
better sedative than a cigar ; a cold day will steady the
nerves better than an opiate ; a trust that a good Power

2/2 ELEMENTS OF PHYSIOLOGY

rules over all will drive away worry quicker than cocaine ;
a cold bath will bring steadier nerves than coffee ; a cold
wind will give a better appetite than food soured with
vinegar or hot with pepper. Natural stimulants do not
produce a reaction because they do not excite the body to
an injurious degree, nor cause the energies to be consumed
beyond the danger point. Persons who go through life
under the stimulus of these natural blessings have sound
steady nerves and clear brains. They do not have to take
anything " to quiet their nerves."

491. Some people are coffee topers and tea topers. It is
a mistake to say these things quiet the nerves. Who is so
nervous as the old lady who drinks frequent cups of tea to
quiet her nerves .? It is the tea that is making her nerves
unsteady. Some people unaccustomed to tea will lie
awake most of the night, wearing out their energies by
sleeplessness if they drink only one cup of it.

492. It is easy to understand how a person sitting up
with a friend who is dangerously ill will take tea or coffee
to keep him wide awake. If he has some great duty to
perform, or trust imposed upon him that will soon be over,
there may possibly be some reason in stimulating his ac-
tivities, even if he must suffer reaction and depression
thereafter. But why one will habitually disturb his body
with narcotics, such as alcohol, tobacco, or even mild nar-
cotics, such as tea and coffee, so as always to keep his vital
force and reserve energy at a low ebb, is difficult to under-
stand. It can only be explained by ignorance of the
fundamental laws of his being.

493. The Use of Natural Stimulants. — Man's body was
beneficently designed to keep a large amount of energy
stored up, so that he can feel conscious of his power and
go through life buoyantly and happily, and prepared for
all emergencies, — the highest being in the world that he
inhabits. He is in a world full of interest. Delicious

STIMULANTS AND NARCOTICS 2/3

fruits and nutritious nuts and grains abound to awaken
and satisfy his appetite. The bright sun not only shines
upon his skin, but deep into it, and stimulates the cells ;
the fresh breezes striking his nerves, start currents cours-
ing through his body. The oxygen penetrates to every
cell, purifying and awakening to life. The pleasure of
association with his fellow-creatures, and various other
pleasures, arouse him to do his part in the world. There
is no need to seek in the jungle for some bitter berry, or
among the weeds for some nauseating leaf, or among de-
caying apples or grapes or fermenting grain for a burning
and revolting liquid in order to stir his being to action.
He lives the life for which his body was designed.

494. How Man comes to deprive himself of Natural
Stimulants. — But suppose he becomes wise and wishes to
improve on the simple blessings of life. He must stay in
the house continually in order to transact much business
and make money, or to acquire precious wisdom in musty
books. He must curtain off the sunshine for fear it will
cause his fineries to fade ; must shut out the air and keep
in the dust. His great knowledge tells him that cool
draughts are dangerous upon a skin made delicate with a
load of clothing. The joys and stimulus of friendship and
of unreserved communion with his fellows leave him, as he
narrows his view and fixes his gaze on some selfish object.
The voluntary motions of his body are confined mostly to
his fingers and his tongue, as he writes and talks in trans-
acting business, for he is too proud to walk, or to work with
his hands, and thus the circulation throughout his body
becomes sluggish. His natural appetite becomes weak and
would regulate the amount of food according to the narrow
incomplete life he is living, but he gets an artificial one,
with sour or peppery seasonings, and the half-digested food
makes poison for his blood. His nerves become weak, his
wit» blunted, his body sluggish and depressed,
T

274 ELEMENTS OF PHYSIOLOGY

495. What this leads to. — He adopts the use of poison-
ous stimulants that, in the effort to rid themselves of the
poisons, the cells may have an incentive to activity, and
the awakening of his weakening system may give him
the feeling of power and enable him to stick to his work
and his unhealthy life. Coffee, tea, tobacco, wine, beer,
whisky, form a gradual progression toward ruin. He
may feel worn out, but a strong cigar, sending the poison-
ous fumes of nicotine into his delicate thin-walled lungs,
will so set his nerves on fire that he feels vigorous, and
says, " What nerve-strength comes from tobacco ! " For
it seems we feel vigorous only when we are expending
energy very rapidly, even if the store of energy is nearly
exhausted. He feels discouraged and weak, and takes a
glass of whisky; this disturbance to the system, with
the great amount of energy expended in getting rid of
it, makes him think he has had a sudden accession of
strength, for he forgets the work that the faithful old
stomach has been doing in storing away food in the cells
(alcohol is never stored in the cells, but all foods are) ; he
forgets the industrious lungs and the oxygen they have been
storing in the blood and cells. He is like the man who has
piled up money in a bank and draws it out with checks
and says : " What a wonderful thing a check is ! How
valuable is my check book ! " But, if he were to lose the
check book, the bank would give him another for nothing.
The check, when written, is only a sign that money must
come out of the bank, and the alcohol when taken into the
body is only a sign that strength must come out of the body
in expelling the enemy. No wonder the man has a bad
headache the next morning.

496. Spendthrifts of Vitality. — Did you ever know per-
sons who could not keep any money or property ? Dollars
seem to burn holes in their pockets. They do not know
how to economize when funds are low, but are always get-

STIMULANTS AND NARCOTICS 2/5

ting in debt and borrowing, and mortgaging their crops or
their stock or their homes. There are many such people,
and there are just as many who cannot store up any of that
precious capital consisting of bodily health and strength. If
they feel buoyant and strong, they will not economize their
strength, but work or go until they are worn out, and then
take tobacco or alcohol to deaden the tired feeling. If a
man is weary, it is not to his interest to feel rested until he
is rested. Such feelings are a cheating of nature, a break-
ing down of the protective barriers around life's citadel.
Such a one deceives himself. One who deceives another
is called a liar ; one who habitually deceives himself brings
the same destruction upon himself as the fool.

497. C. F. Hodge, Professor of Physiology in Clark
University, made a series of experiments upon four
kittens and four spaniels. Moderate non-intoxicant doses
of alcohol were given daily to two of each.

(Dogs could be killed in a few minutes or a few days or
months by sufficiently large doses of alcohol. While such
experiments might have some interest to toxicology, they
could not have much to physiology.)

498. At the end of ten days, the two kittens dosed with
alcohol took severe colds. Up to this time, purring and
playfulness had been disappearing from their lives. They
were dwarfed in growth to 63 and 39 per cent, respec-
tively, as compared with the others.

499. Of the two pairs of spaniels, the pair treated with
alcohol weighed less, and developed only 71 and 57 per
cent of the activity of the other pair, as shown by the pe-
dometer. The dogs treated with alcohol also developed
strange symptoms of timidity and fear, suggesting the ter-
rible fears of delirium tremens and alcoholic insanity.

500. In Dr. Hodge's opinion the experiments above
described have direct bearing on the question of the effect
of alcohol on the human system. The experiments proved

276 ELEMENTS OF PHYSIOLOGY

that alcohol causes depression of activity. For man the

highest aim is to develop useful activity, the will, the deter-
mination to do as much of the world's necessary work as
he is capable of doing, and a sound, vigorous body to
enable him to carry out such determination. It is of the
utmost importance, therefore, that we understand the con-
ditions of our physical systems under which this great end
can best be attained.

501. In no other country are there so many people who
refrain from using intoxicating liquors as in the United
States. Many forces have united to bring about this con-
dition, chiefly temperance organizations, ministers, teach-
ers, and the newspapers. To a greater extent than in other
countries also intemperance has been driven out from the
upper classes by the force of public opinion ; it is no longer
fashionable. Temperance has gained in spite of the fact
that the climate of the United States tends strongly to
cause the excessive use of alcoholic liquors.

502. A Knowledge of Physiology is a great help in pro-
moting the cause of temperance. All who acquire such
knowledge are the better able to contribute their share to
the good work. There can be no doubt that the use of
alcohol is steadily diminishing as the people learn more
of physiology, especially of the true nature of alcohol and
of its effects on the system. General education also fights
against intemperance, as few people interested in gaining
knowledge care to indulge to excess in intoxicating
drinks.

503. Why the Drinker increases his Dram. — Tanner
and Succi have proved that for the ordinary man the
energy stored up is sufficient for many weeks of life with-
out replenishing it by taking one morsel of food. When a
man begins to drink, the energy of his body may be of
large amount, and a small amount of alcohol suffices to
stimulate and exhilarate him. But a few stimulations

STIMULANTS AND NARCOTICS

serve to cause a large part of his energy to be con-
sumed, and a larger amount of stimulant is therefore
required to arouse to action the exhausted cells. Thus
it goes on ; the more he abuses his system by arousing it
to expel the poison, the less energy he has left and the
more difficult it is to arouse. The nearer worn out the
tired horse is, the sharper must it be lashed to keep it go-
ing. The habitual user of alcohol is not only its slave, but
a slave that is constantly being drawn closer and closer
within its relentless clutches. The energy of the cigarette
user sinks to a lower and lower ebb, and he constantly
increases the nicotine in order to arouse it.

504. Inebriate Cures. — These are sometimes successful,
but are usually failures. What makes the cure of the
drunkard so difficult is, that he is not really willing to
undergo the pain and trouble necessary to stop. During
some unselfish moments, and when he realizes more than
usual the destruction that dissipation is bringing upon him,
he may truthfully desire to make any sacrifice to free him-
self and become restored to manhood, but so ruinous has
been the effect of alcohol upon his moral nature, that such
moments do not last long, and when the first promptings of
the appetite return, he falls, and would sell the roof from
over the heads of his wife and children to get money to
gratify his thirst. The inebriate cures base their method
upon convincing him, by secretly adding a nauseating dose
to his drink, or by some other plan, that alcohol has turned
against him and no longer gives him pleasure, and he be-
comes convinced that he must stop, and willing to try to
quit. The best way to quit alcohol, opium, tobacco, or
other narcotics, is by a straightforward resolve to do so, and
by stopping at once. While the poison is being removed
from the body, the nerves are so irritable that the least
sound or change of temperature may bring torture to the
patient, and sometimes it is necessary to keep him in a quiet

278

ELEMENTS OF PHYSIOLOGY

room, submerged in a bath just the temperature of the

body, for several days at a time.

505. The Discovery of Alcohol. — A long time ago learned

men called alchemists (the predecessors of the chemists of

the present day) be-
lieved that they could
succeed in discover-
ing the elixir of life,

•j *f A the water of perpetual

youth. In the year
1000, an Arab alchem-
ist, while seeking the
elixir of life, discov-
ered alcohol. Of
course it had existed
long before, wherever
fermentation of sugar
took place, and had
been drunk in wine,
in which it occurs in
a diluted condition.
But this alchemist suc-
ceeded in distilling, or
evaporating and con-
densing, it from the
water of the wine.
When he first drank
alcohol, he felt that
he had some new and
strange liquid which
he believed would
prove to be the water

FlG. 191. — An illustration of the nerve branches
and fibers in a case of alcoholic insanity. The
patient died of this disease and when the nerve
fibers were examined under the microscope,
they were shown to be swollen and broken
down in the manner illustrated in the drawing.
The swellings of the nerve fibers, as seen in this
illustration, are characteristic effects produced
by alcohol, and are usually seen in the brain
of those dying from alcoholic insanity.

of life. But experi-
ence soon showed that the use of it, instead of giving
freedom from death and perpetual youth, shortened life

STIMULANTS AND NARCOTICS

279

instead. Yet the name "water of life" is still the term
used for brandy in the French language, and one may
see in immense letters on a wall at the end of a street near
the University of Paris, the suggestive sign, Dfyot de V Eau
de Vie, " Storehouse of the Water of Life."

506. Truly the Bible gives the heart of the matter when
it speaks of wine and those who are deceived thereby ; for
the deception of a part of

mankind has been com-
plete. The use of narcotics
has been pronounced a blot
upon civilization, and phys-
iologists and sociologists
have united in declaring
that alcohol ranks ahead
of war and other evils as
the greatest obstacle to
civilization and the happi-
ness of mankind, that exists
in the world.

507, Of all the Diseases
that have been named as
being caused by alcohol, no
one person ever has more

than a small part. Those of the organs that are weakest give
way first, and death results before the others are attacked.
The stomach may become so ulcerated that it cannot even
bear water, which throws the victim into a spasm. In such
a case, he will probably die in delirium tremens, a condi-
tion of horrible temporary insanity.

The body seems in some instances to become used to
the moderate use of poisons such as nicotine and alcohol,
and in outward appearance to escape serious harm.
For one that apparently escapes, many are destroyed. We
sometimes see very old men that have smoked tobacco for

FIG. 192. — This figure shows four nerve
cells from the brain of a man who died
of alcoholic insanity. It will be noticed
that the body of the cells and the nerve
fibers are broken up and degenerated.
The changes shown in Fig. 191 are
the more severe changes, and represent
complete destruction of the nerve tissue.

280 ELEMENTS OF PHYSIOLOGY

fifty years. But if such men had begun when young
boys, or had used cigarettes and inhaled the smoke, they
would be even fewer than they are.

508. Review of Effects of Alcohol. — Give the effect of
alcohol upon (i) the skin and bones; (2) the muscles; (3)
the stomach; (4) the liver; (5) the circulation; (6) the
respiration ; (7) the nervous system. (8) Discuss whether
alcohol is a food.

509. Drug Habits are growing with such rapidity that it
is a question whether the drug fiend will not, before long,
be as common as the drunkard. The physician meets few
more pitiable sights than that presented by the typical
morphine or cocaine fiend. The evil is invading all classes
of society, including numbers of physicians. Many patent
medicines, cough cures, headache powders, colic cures, etc.,
contain morphine. It is a deep-seated fallacy existing in
the minds of the masses, that they can violate with im-
punity the laws of health and life which have been insti-
tuted by infinite power and wisdom, and then dodge the
unpleasant consequences by simply swallowing a few drops
of some sedative or anodyne. About $200,000,000 worth
of patent nostrums are annually disposed of. The aver-
age invalid demands something more substantial than
extravagant claims. As there is no drug that will so
effectually smother, for a time, the cries of an outraged
nerve as some form of opium, and as there is no drug that
is so deceptive a stimulant as cocaine, these two are most
often found in these quack remedies. They assist in secur-
ing convincing testimonials as to the wonderful curative
power, which is supposed to be identical with the relief
from pain furnished. The invalid soon learns to buy the
active agent in the nostrum in its pure form, and this often
seals his fate.

510. Subjects for Compositions. — Cooking. Health and
the Home. The Body subject to Law. Improved Dress.

STIMULANTS AND NARCOTICS 28 1

Some of my Observations and Experiences from the Stand-
point of Physiology. Tight Shoes. An Incident from
Life. Physical Education compared with Mental. Hy-
giene of the Schoolroom. Extremes in Hygiene. Microbes.
Health and Country Life. Looking Back. Looking
Ahead. Health and City Life. The Right Way the
Easiest.

PART IV. HOW THE BODY IS CON-
TROLLED

CHAPTER XVI

THE NERVOUS SYSTEM

511. Function of Nervous System. — The ameba and
other one-celled animals need no nervous system, but the
larger animals, consisting of a colony of cells, as it were,
need a means of communication between the cells, in order
that their life may be harmonious. Robinson Crusoe could
not have used a telephone or a post office system, but a
number of individuals living together and practicing a
division of the labor of the community for their mutual
advantage, are compelled to communicate with each other
in order to make their necessities known. The lowest of
the many-celled animals, such as the sponges, have no cells
specially set apart for carrying messages between the
cells, but each cell passes the impulses it receives to its
neighbor cell. This will do for a small and simple com-
munity of cells, but a larger community, like one of the
higher animals, possesses certain cells, called nerve cells,
whose chief function is to keep up the communication
between the cells. In the chapter on the master tissues
you learned that the nerve cells did this by means of long
branches, which in some cases are several feet long.

512. Communication is not All that is necessary. — Did
you ever see a crowd of people at a fire when a neighbor's
house was burning ? Everybody ran about, yet very little
was done. Everybody shouted orders which nobody obeyed.
But on the arrival of the chief of the fire department or
the head of a fire company, who had had experience in

282

THE NERVOUS SYSTEM 283

the control of men fighting a fire, the scene changed ;
valuable property was saved, and the fire was stopped.

513. Every community has certain deliberative and con-
trolling bodies ; these may be a board of aldermen, a court
of justice, a legislature, or a congress. In a similar way
the great number of individual cells which make up the
human body must be controlled by some central power,
or they will not work in harmony ; nothing will be accom-
plished, but a state of anarchy and helplessness called
disease, will follow. The seat of this central controlling
power is believed to be located in the brain.

514. Coordination. — The nerve cells receive, modify, and
send out impulses. By these three kinds of acts the ner-
vous system accomplishes what is called coordination.
This term signifies not only that the cells work together at
the same time, but that they work together as a part of a
plan for the accomplishment of some definite result. Sup-
pose that a man sees a bright dollar in the road and
picks it up. In order that he may do this, the cells re-
ceiving through the optic nerve the impression of the
shining coin must be in communication, either directly
or indirectly, with the muscles of the hand ; and that the
hand may reach the coin, the muscles of the arms, legs,
trunk, head, and neck must act together. Even the heart
and respiratory muscles must modify their action somewhat
to suit the movement.

515. Other Organs besides Muscles must be coordinated.
— Suppose a boy sees a large red apple. He notices the
odor which tells him that it is ripe, and his " mouth waters "
for it ; that is, the salivary glands begin to work, even before
he puts the apple to his mouth. The chewing and swal-
lowing, the secretion and peristalsis in the digestive organs,
are all carried on under the control of impulses that reach
them through the nerves. Without these impulses, the
salivary glands would not work when the mouth was chew-

284

ELEMENTS OF PHYSIOLOGY

ing the food ; the dry food would stick to the esophagus
and have to be washed down with water; the gastric juice

would not be secreted at just
the right time; the food would
ferment in the stomach, and
the person would soon be ill.
516. Nerve Cells (Fig. 193).
-You learned when studying
the master tissues that the ner-
vous system consists of nerve
cells with their branches, called
nerve fibers. Nerve cells are
microscopic bits of protoplasm,
like other cells, yet they are
remarkable among animal cells
for their large size. Some of
the cell bodies in the spinal
*cord are so large as to be almost
visible to the unaided eye, and
have branches leading from
the cord to the hand or foot.
Each cell contains a nucleus,
within which is a nucleolus
(Fig. 193). Nerve cells are
the most remarkable in the
body for irregularity of shape ;
some of them have so many
branches that they have a star-
like appearance.

. — Branched Nerve Cell from

Spinal Cord. 517. The Dendrons of a nerve

a, axis cylinder or axon; bt dendrons; c, cell are the treelike branches

which bring impulses to the

cell (Fig. 193). Through the dendrons the cell may be in
communication with numerous other cells. 'A branch of
one cell does not join the branch of another cell. It has

THE NERVOUS SYSTEM

285

not yet been settled by physiologists whether the ends of
the dendrons of communicating cells actually touch.

518. The Axis Cylinder, or Axon. — In most of the fully
developed nerve cells, one of the branches is very greatly
prolonged as a fine thread of protoplasm,

which becomes the core of a nerve fiber
(Fig. 193). Every nerve fiber has such a
core. In most of them this central thread
of protoplasm becomes covered with two
coats ; an outside protective coat forms
a tube, called the connective sheath : and
between the walls of this tube and the
central thread is a coat of semiliquid, fatty
substance called the medullary sheath,
which, shining through this outer sheath,
gives a silvery white appearance to the
fiber. Such fibers are called medullated
fibers, or white fibers (Fig. 194). Some
fibers lack the medullary sheath, and are
called non-medullated) or gray fibers (Fig.

194).

519. A Neuron. — One nerve cell to-
gether with all its branches, both dendrons and axon, is
called a neuron. A neuron is the unit, and the nervous
system is built up of an enormous number of these units,
together with supporting tissue (Fig. 193).

520. A Nerve. — Many nerve fibers may be bound to-
gether by connective tissue until they form a cord large
enough to be seen by the unaided eye (Fig. 195). A bun-
dle of nerve fibers is called a nerve. The sciatic nerve in
the thigh is as large as the end of the little finger and strong
enough to support the weight of the body. The fatty
sheaths of the fibers are supposed to insulate the fibers so
that a nerve impulse cannot go across to another fiber; they
serve the same purpose as the insulating substances with

FIG. 194.

c, medullated or white
nerve fiber; rf, two
non-medullated or
gray fibers.

286 ELEMENTS OF PHYSIOLOGY

which wires used to conduct electricity are sometimes
coated. As a rule, a large nerve accompanies an artery
down the inside of each limb, and across the joint on the
side toward which the limb bends. Thus they are well
protected. One exception to this is a
nerve cord which crosses the elbow on
the side away from which the elbow
bends. Therefore it is sometimes hit,
and the end of the bone there is called
the funny bone because of the tingling
sometimes felt, as if it were in the hand
at the termination of the nerve.

521. A Nerve Ganglion and a Nerve
Center. — The cells are not scattered
singly throughout the nervous system
but are gathered into groups. This
seems to afford easier communication
from one cell to another through their
branched dendrons, which are unusually

FlG. 195. — Section of . _ r .. . ,, .

Nerves, showing Many short. One SUCh group of Cells IS Called

Nerve Fibers in Con- a ganglion. One or more ganglia,

nective Tissue Sheaths. 6r 6.

performing a definite function, such as
controlling the muscles of breathing, form what is called a
nerve center. The brain consists of a number of large nerve
centers with their connecting fibers. There are many
nerve centers in the spinal cord also. We usually speak
of the brain and spinal cord as the central nervous system.
Where ganglia and gray fibers are abundant, the nerve
substance is gray ; where medullated fibers with their hid-
den gray cores are abundant, the nerve substance is white
in appearance. This led anatomists and physiologists in
times past to classify nerve substance as gray matter and
white matter.

522. Neuroglia. — The fibers and cells of both the gray
and the white matter are held in place by a tissue called

THE NERVOUS SYSTEM 28?

neuroglia, which is composed of extremely fine fibers and
minute cells. Though like connective tissue in function,
its chemical composition is different, nor is neuroglia de-
veloped from connective tissue (Fig. 193).

523. How Nerve Fibers terminate. — If we could trace
toward the central nervous system the course of the various
nerve fibers in a nerve like the great sciatic, for example,
we should find that every one of its thousands of nerve
fibers ends, without exception, in a nerve cell in the spinal
cord or brain, or in one of the ganglia near the central
nervous system. If we should trace these same fibers
away from the central nervous system, they would be found
to have various endings. Some enter the muscles where
they subdivide, and finally end in the muscle cells. Others
follow the blood vessels, and end in the muscle fibers form-
ing the middle layer of their walls. Others go to the gland
cells ; for example, the sweat glands in the skin, or to some
other internal gland. Others, passing to the skin, termi-
nate at the roots of the hair, or in curious little bodies com-
posed of cells and called touch corpuscles (Fig. 196).
Every nerve fiber ends centrally in a nerve cell, and out-
wardly in either a muscle cell, gland cell, or sense organ cell.

524. Motor and Sensory Fibers. — Fibers which connect
nerve cells with muscles or glands are called motor or
efferent (outward bearing), fibers ; those which connect
nerve cells with sense organs are called sensory or afferent
(into bearing) fibers. There is a third kind, which connects
nerve cell with nerve cell in the brain ; they are known as
association fibers (Figs. 203, 207).

525. Nerve Action. — If the sensory nerve be irritated at
its outer endings in the cells of the other tissues or any-
where in its course, an influence will travel to the central
nervous system. If the impulse reaches the brain before
dying out, it will be felt as a sensation. On the other hand,
the brain can originate impulses which travel to the cells of

288

ELEMENTS OF PHYSIOLOGY

the body and cause them to act. Transmitting impulses
is the whole duty of nerves. The endings of the nerves
are so abundant in the skin just beneath the epithelium,
that the point of a fine needle cannot enter without causing
pain. They are more numerous there than in any other
part of the body. Sensory nerves are not so abundant in
the muscles and internal organs as in
the skin, so that a cut gives most pain
as it enters the skin and may be con-
tinued into deeper parts with only
slight pain. Motor nerves begin at
the central nerve cells and end in the
cells of the body. Motor nerves and
motor impulses are for three pur-
poses : for controlling motion, secre-
tion, and growth.

526. Special Sensations. — When
something outside of the body acts
upon the nerves, it produces a feel-
ing or sensation by which the mind
forms ideas of the surroundings of
the body. The meanings of these
feelings must be learned when first
stained with Chiorid of perceived, and they are mostly learned
in childhood. The special senses are
of such importance that all except
the sense of touch will be included
in a separate chapter.
527. General Sensations. — The cells of the body are
constantly sending impulses to the central nervous system,
signifying their needs. These impulses give rise to feelings
to which the mind assigns no definite location in the body ;
hence they are called general sensations. Such feelings as
hunger, thirst, fatigue, and sleepiness belong to this class.
They are as well understood by a baby or any young

FIG. 196. — Tactile Cor-
puscle within a Papilla
of the Skin of the Hand,

Gold.

n, two nerve fibers passing to
the corpuscle ; a, a, ramifica-
tions of the axis cylinders
within the corpuscle.

THE NERVOUS SYSTEM 289

animal as by a man, and unlike the special sensations, the
meaning of general sensations does not have to be learned,
as the memory of them owing to inherited habit seems to
reside in the nervous system. General sensations are
sometimes called instincts.

528. Hunger and Thirst — Thirst seems to be located in
the mouth, yet moistening the mouth satisfies it for a short
time only. On the other hand, if water is introduced into
the body through the intestine or veins, the thirst ceases,
even if the mouth has not received water. Hunger appears
to be located in the stomach, yet it cannot be satisfied by
filling the stomach if the food is innutritious or remains
undigested.1

529. Touch. — The four special senses of sight, sound,
smell, and taste are located in special organs. Touch is
located in all parts of the body. When an object touches
the skin, an impulse is taken to the brain (Figs. 196,
197, 3). There it gives rise to a sensation of touch, tem-
perature, pain, or weight. Four kinds of sensations are thus
included in the general name of touch. Touch strictly
gives only such ideas as those of size, shape, location,
smoothness, hardness, and dampness. The ends of the
fingers can distinguish two points as separate points if
they are only -^ of an inch apart, while if the two points
are applied to the back, they feel as if they were one point
until they are separated two inches.

530. The covering of epidermis not only protects the
nerves and the other delicate organs in the true skin, from
injury, but also modifies any impression, so that in pro-
ducing a sensation it is spread over several nerve endings
instead of one, and is thus turned into a gentle instead of
a painful sensation (Fig. 3).

1 If nutritious food is introduced into the body through the intestine in a
form ready to be absorbed, the feeling of hunger will soon pass away, although
the stomach is still empty.

U

290

ELEMENTS OF PHYSIOLOGY

531, Temperature. — This part of the sense of touch is
located only in certain points or spots, called heat spots

and cold spots, situated a
small fraction of an inch
apart (Fig. 198). Some
spots give a sensation of
heat only, and some of
cold only. The sense is
so delicate that a differ-
ence of \ of a degree of

FIG. 197. — Four Papillae of the True Skin,

magnified. The epidermis has been re- temperature between two
moved. Most papillae contain touch cor- objects Can be detected.

Extremely hot and cold

objects injure the tissues and do not give sensations of
temperature, but only of pain.

532. Pain. — A sensation
greatly increased or often re-
peated becomes unpleasant
and is called pain. The same
physical influence may be
felt at one time as a pleasant
touch, and at another time as
a pain, depending upon the
state of the nerve tissue.
When an influence is becom-
ing strong enough to endan-
ger the body, the simple
sensation of touch becomes
changed into one of pain
and warns us to avoid the
danger. When a nerve is
laid bare and touched, or cut
midway in its course, the feel-
ing is not one of touch, but of pain. Pain is a protection,
and therefore more of a good than an evil. In many

FIG. 198. — Cutaneous "Cold" Spots
(light shading) and "Hot" Spots
(dark shading) ; Anterior Surface of
the Thigh.

THE NERVOUS SYSTEM 29 1

diseases it is a prominent symptom, and the physician is
begged to give relief. But the wise physician hesitates be-
fore giving morphine or other sedatives, knowing that to
drown the pain is to conceal the danger, and take away his
best evidence as to the state of the disease. At the same
time, he runs a risk of starting a habit in the patient of
deadening pain and hiding unpleasant feelings by taking nar-
cotics, a habit that may become fastened upon the patient
and ruin his life. Hence when sick we should bear pain
bravely.

533. Tickling is intermediate between touch and pain.
It is produced in parts which are supplied with few nerves
of touch, as under the arm. It may produce great suffer-
ing. Some persons who can endure great pain cannot
control themselves when tickled, as the movements excited
are largely reflex. Itching is a sensation akin to tickling.
It may be overcome by producing a greater sensation, as
by scratching. Sometimes it may be so great as to lead
a person to injure the skin seriously by deep scratching.

534. The Muscular Sense. — When an object is lifted, it
is felt to be distinctly heavier if its weight is increased by
only Tay> but when it is laid upon the skin, its weight must
be increased by \ before it feels heavier. Hence it is
concluded that sensations of weight and resistance to the
muscles depend upon the amount of muscular effort needed
to overcome the resistance as well as upon the feelings
of pressure upon the skin and body.

535. If Motor or Efferent Nerves going to a muscle are
cut, there is paralysis of the muscle, so that there can be no
voluntary or reflex action in the part. If an efferent nerve
going to a gland is cut, the function of the gland will be almost
suspended. Even if food is taken into the mouth and the
sensory nerves carry the news to the brain, the efferent
nerve being cut, no impulse can return and the secretion
will be very slight. When the motor nerve to a part is

ELEMENTS OF PHYSIOLOGY

cut, the cells will be almost too inactive to absorb and
carry on growth and repair; hence unless continually
under the influence of motor nerves the cells dwindle
away. When the cells are much used, the impulses sent
cause them to take in more nourishment and grow in size.
Thus a muscle increases in size and strength when much
used. You learned that during the action of a muscle, the
vasomotor nerves going to the arteries in the muscle cause
what change ? Will this also aid in growth ? When a
nerve is cut, the ends, if placed together, will grow again,
the parts supplied by it being paralyzed in the meantime.

536. Disease of Nerves and Effect of Alcohol. — Nerves
may become inflamed, and the disease is called neuritis,
just as inflammation of the tonsils is called tonsilitis, or of
the stomach is called gastritis. Neuritis of the sciatic
nerve is called sciatica ; it is a very painful disease. One
of the many dangers of using alcohol is that it may pro-
duce neuritis. Either slow, steady drinking or occasional
sprees may cause it. The disease gives no warning before
it comes, and may remain a long while. Rheumatism or
malaria may also cause it, but alcohol produces the disease
as often as all other causes combined.

537. The Rate of Transmission of the nerve impulse in
white fibers is about one hundred feet per second. In the
gray fibers the impulse travels much slower, probably about
twenty feet per second.

THE SPINAL CORD

538. The various white nerve fibers, both motor and
sensory, of the entire body unite and form forty-three
pairs of larger nerves ; twelve of these pairs, called cranial
nervesy go to the brain, and thirty-one pairs, called spinal
nerves, go to the spinal cord. Each one of the sixty-two
spinal nerves enters the spinal cord by two roots, one pos-
terior and one anterior (Fig. 199). It is significant that

THE NERVOUS SYSTEM 293

all of the motor and sensory fibers of a spinal nerve sepa-

rate from each other. The motor fibers enter by the an-

terior root, and the sensory nerves by the posterior root.

The sensory fibers do not really

enter the cord but end in a ganglion

on the posterior root, and the gan-

glion sends dendrons into the cord

by the posterior root. The spinal FIG. 199. — Cross-section of

cord extends from the foramen mag- %^ «£ •££

" Or great Opening," in the OCci- and Anterior and Posterior

..-•1 i , , Nerve Roots. Ganglion on

pital bone down to about the second Posterior Root.
lumbar vertebra. What parts of a

vertebra form the canal for the cord ? Is the canal made
of bone throughout its length ? How are the vertebrae
united with one another?

539. The spinal cord is about the size of the little finger.
It is only about two thirds as large as its tube, so that it is not
likely to be injured by bending the backbone. The rest of
the space in the canal is taken up by a lymphlike liquid and
three membranes called meninges, which form a triple cov-
ering for the cord. These membranes extend into the skull
and cover the brain. An inflammation of them constitutes
a very serious disease called cerebro-spinal meningitis.

540. A Cross-section of the spinal cord shows that it
is a double organ (Fig. 199), the halves being united by a
narrow portion ; it shows also that the central part of the
cord is of gray matter in the outline of a butterfly, and sur-
rounded by a thick layer of white fibers. The gray por-
tion is made up of nerve cells that give off fibers, many of
which go to the spinal nerves and some go upward in the
outer white portion of the cord. The white tract also con-
tains motor threads, bringing impulses from the brain to
the cells in the gray matter.

541. Voluntary Motion and Action of the Spinal Cells. —
The brain sends impulses to the cells in the spinal cord,

294 ELEMENTS OF PHYSIOLOGY

and they, being aroused, in turn send motor impulses to
the muscles. When a person wills to move his hand, an
impulse goes to the spinal cells, and they in turn send im-
pulses that cause a contraction of the muscles in the arm.
The brain sends about ten impulses per second to keep the
muscle in action. Thus, before it can relax, another im-
pulse reaches it. Each muscle has its own set of spinal
cells in the cord which act as a relay station between the
muscle and the brain.

542. The Spinal Cord and Reflex Action. — The cells of
the spinal cord have another very important duty ; they
largely control reflex action. At times it would take too
long for the brain to act, so the body needs a quicker
governing power to supply its needs or protect it from
injury. If the finger touches a hot object, the brain be-
comes conscious of the burn and of the movement of the
finger at about the same time. There are also many acts
that are performed so often that the spinal cord acquires
the habit of sending back the appropriate impulses. Thus
muscles and other organs may be controlled and the brain
be relieved to attend to other duties.

543. The same motor cells of the spinal cord that pro-
duce motion in a part, also exercise an oversight that con-
trols the growth and nutrition of the cells in that part.
The impulses from the spinal cells furnish a constant
stimulus to growth and repair.

544. Examples of Reflex Action. — A crumb entering the
larynx brings on a fit of coughing. A dash of cold water
makes us hold our breath. A pinch of snuff or pepper
causes us to sneeze. If the foot of a sleeping person is
tickled, he will kick ; if a fly settles on his face, he will
brush it off. Sometimes a person in an unconscious con-
dition will drink a cup of water if it is placed to the lips.

545. If the back is broken, reflex actions persist although
all sensation and volition concerning the parts below the

THE NERVOUS SYSTEM 2Q5

injury are suspended. The leg will kick when the foot is
tickled, etc. A surgeon tickled the foot of a man whose
spinal cord was injured, and the feet kept up a vigorous
kicking. He asked the man if he felt it ; he said, " No,
but you see that my feet do." On carefully testing the
sensibility of such a man, a line can be traced girdling the
body, dividing the sensitive from the insensitive part. The
brain also may act seemingly in a reflex manner as in
cases of somnambulism, or sleep-walking.

546. When one is learning new movements, such as
walking, skating, writing, riding a bicycle, each movement
is a voluntary one as far as the will is capable of watching
so many muscles. The movements are, therefore, slow
and awkward. After the movements have been made
many hundreds of times, they becomes easy and graceful,
and also less voluntary. Finally, one may learn to walk,
cycle, or play the piano with the attention fixed on some-
thing else. Such movements are called " acquired re-
flexes." There is evidence to show that the axons become
covered with a medullated coat, as each new pathway and
tract is beaten through the nervous system by repeated ex-
periences. Thus the structure, like the habit, becomes fixed.

547. Reflex Action and Education. — Education of reflex
action consists mainly of the formation of habits. The im-
pression on the nervous system from the training is made
chiefly on the spinal centers. When the muscles of the
hand are educated, it is really the spinal cells that are
educated. During youth, one is always acquiring good
habits or bad habits. The habit of an upright, easy walk,
the habit of dropping into a stooping posture, of putting
the hands in the pockets, of making wry faces, of mum-
bling and stammering, or of talking distinctly and without
hesitation, may be acquired, and will probably remain
ihrough life, tor impressions made on the nervous system
in youth are lasting. The habit of Beating temperately of

2Q6 ELEMENTS OF PHYSIOLOGY

pure food, the habit of stuffing, of awaking the nerves with
stimulating condiments, of using alcoholic stimulants, of
using tobacco, are easily acquired, but are lost with
difficulty. Good habits are good friends; bad habits are
enemies. It often requires years of constant effort to root
out bad habits, but it is very easy to keep them out in the
first place. Yet if the wish and will for a better habit is
really strong, one need never despair, for on account of the
large size and great activity of the brain, and its prepon-
derance over the lower reflex centers, man is distinguished
above all other animals by his power of forming new habits.
If our ideals are high, we can go on forming better habits,
and intrusting them to the keeping of the nerve centers, and
thus make step after step toward our ideal. If our ideals
are not high, or if they are mere theories and never affect
our acts, we may never improve, but may even degenerate.
The brain and the spinal cord with the nerves that branch
from them form the cerebro-spinal system.

THE SYMPATHETIC, OR GANGLIONIC, SYSTEM

548. This System consists of numerous ganglia situated
apart from the brain and spinal cord, and many gray nerve
fibers which connect these ganglia with the spinal cord,
with each other, and with the cells controlled through this
system. (What is lacking in the gray fibers that is present
in white fibers ?) The sympathetic nervous system con-
trols the functions of unconscious life, while the brain and
spinal cord control the functions of conscious life.

549. The chief functions controlled through the sympa-
thetic system are the peristalsis of the intestine, the growth
of cells, and the contraction of the heart, arteries, and veins.
The nerves that go to the arteries and veins are named
the vasomotor nerves. The ganglia of the system vary
in size from minute specks to the size of a grain of wheat,
a pea, or a bean. There is a double row of the large ones

THE NERVOUS SYSTEM

297

that runs down in front of the backbone, all connected by
nerves. The nerves of the system form several intricate
networks, each 'called a plexus
(Fig. 200). The largest and
most important is the solar
plexus, just behind the stom-
ach; its nerves supply the
muscular walls of the abdomi-
nal organs. Another plexus is
found in connection with the
heart.

550. Sensory Nerves of the
Sympathetic System. - - The
sensory impulses through these
nerves are slow and faint, sel-
dom reaching beyond the spinal
ganglia to the brain. Thus
the circulation of the blood
and the digestion of the food
usually go on without our con-
sciousness, but a very strong
irritation may give rise to con-
sciousness and pain in the
abdominal organs, as in colic
or in vomiting. Sensory im-
pulses, signifying the needs of

the cells and the necessitv for FIG. 200. - Diagram of Trunk show-
in? One of the Two Rows of Svmoa-

movement in the arteries and
intestines, are being continu-
ally sent to the spinal ganglia.
Only very strong impulses
caused by disturbances that may injure the body, reach
the brain, and cause pain.

551. Motor Sympathetic Nerves. — The motor nerves
carry impulses which cause the epithelial cells of the

ing One of the Two Rows of Sympa-
thetic Ganglia near the Spinal
Column and the Plexuses.

i, cardiac plexus; 2, solar plexus; 3, hy-
pogastric plexus; 4, 5, 6, 7, row of
ganglia near spinal column.

298 ELEMENTS OF PHYSIOLOGY

glands to make their secretions, and the muscles of the
arteries and intestines to contract. They do this as a
reflex response to the impulses going to the spinal ganglia
from the sensory nerves of the system. The pressure of
food in the stomach excites the flow of the secretions. At
a flash of bright light the eye winks and the pupil con-
tracts. The sweat glands secrete under the influence of
warmth. It was formerly believed by physiologists that
the sympathetic ganglia themselves sent the reflex motor
impulses, but it is now believed that these come from the
spinal ganglia. The sympathetic ganglia are supposed to
reenforce the current and aid in the nutrition of the nerves
that pass through them.

552. The Brain has Considerable Influence over the
sympathetic nerves, but in an indirect way. We can-
not control the digestion or the heart beat by the will, yet
the thoughts and emotions may powerfully affect them.
The face blushes from dilatation of its blood vessels when
one is embarrassed or self-conscious. It becomes pallid
with fear. Sorrow depresses the activity of the cord,
which in turn sends out fewer orders, so that the food is
not digested and the cells are not nourished. Yet to
guard against too great interference by the emotions and
the mind, nature has arranged that impulses starting at
the brain must pass through at least two sets of ganglia
before they can affect nutrition and circulation. The
examination of the food is carried on by the higher senses
and the brain, for it is important that hard things and
poisonous substances should not be swallowed. But the
regulation of the flow of the saliva is left to the gray
matter at the top of the spinal cord ; the secretion of the
saliva is a reflex act excited by the taste of the food, and
does not enter into consciousness.

553. Strong influences are needed to impair the action
of the sympathetic nerves and ganglia. Poisons which

THE NERVOUS SYSTEM 299

are swallowed or produced in the body by disease, may
excite them to vigorous action and cause vomiting, or may
injure them so that their impulses almost cease. Aside
from this, about the only danger to which the system is
exposed is a blow upon the abdomen or neck ; such a blow
is always dangerous. Death may then result through shock
to the heart, or through paralysis of the vasomotor nerves,
which causes the arteries to enlarge and hold so much
blood that too little goes to the brain. " Fidgets " is caused
by poisons from fermented food going to the sympathetic
ganglia and irritating them. Backache in women is some-
times caused by the abdominal organs being prolapsed or
pushed downward by the pressure of a tight corset, or pulled
down by the weight of skirts supported by these organs.
This causes the sympathetic nerves to be stretched at their
attachment near the spine.

554. Sympathy in functional activity between the va-
rious vital organs is brought about through this system, and
gives it its name. Derangement of the stomach may affect
the heart. One organ seems to share in the illness when
another is deranged. This is well, for when one organ is
diseased, the others do not continue to act and impose work
upon the ailing organ. A feeling of weakness, which rests
the muscles, and a loss of appetite, which rests the digestive
organs, accompany most forms of illness.

555. THOUGHT LESSON. Obedience to Natural Law. —

1. What is the natural direction of growth of the big
toe?

2. Think of six evil results, direct or indirect, which will
follow the transgression of God's design in this simple
matter.

3. Which part of the spinal column, designed in infinite
wisdom to be most flexible, do some people try to make the
most inflexible ?

4. The mobility of the false and floating ribs was intended

3OO ELEMENTS OF PHYSIOLOGY

as a blessing. Some people interpret the blessing as an
opportunity to do what?

5. Name six articles which God has warned us are in-
jurious by giving them bitter, burning, or nauseating tastes,
yet which are used by man.

6. Name six feelings which are intended as warnings
for our guidance, but which are commonly disregarded.

THE BRAIN

556. The spinal cord can act only in response to im-
pulses at the moment they are received. The brain can
originate impulses which are not in direct response to a
stimulus from the outer world. Its acts are apparently
spontaneous, but they probably result from the combina-
tion of impulses previously received, which memory has en-
abled it to store up and retain. The brain not only causes
action and directs the cord in giving order to voluntary
movements, but it can restrain excessive action in the spinal
cord. Self-control comes largely through the power pos-
sessed by the brain of restraining the spinal cells from
sending out reflex impulses when strong and sudden im-
pulses are received from the outer world. This is called
the inhibitory power. If a door slams, a person whose
brain is not exerting good control jumps suddenly.

557. The Coverings of the Brain. — What facts did you
learn about the skull, showing that it is well constructed
for protecting the brain ? The brain is covered by three
membranes ; the outer tough one lines the skull and the
spinal canal. The next is thinner. There is a lymphlike
fluid, called the cerebro-spinal fluid, within this membrane,
so that the brain is surrounded by a kind of water bed.
The third, and innermost covering, is hardly a membrane,
for it is merely a thin network of fine blood vessels and
connective tissue. It dips down into every depression and

THE NERVOUS SYSTEM 301

fold of the outer layer of gray cells of the brain,
carrying its supply of blood. This layer is called the
cortex. The folds are called Convolutions (see Plate
VII).

558, The Weight of the Brain of the average man is forty-
nine ounces (a little over three pounds), and of the average
woman is forty-four ounces. The woman's brain is as large
in proportion to the size of her body as man's brain.
Man's brain is surpassed in weight by the brains of only
two animals. A whale, measuring seventy feet long, has
a brain weighing only five pounds, and an elephant's enor-
mous body is controlled by a brain of about eight pounds.
Birds' brains are heavier in proportion to their bodies than
the brain of any other animal. The brain grows very
rapidly till the fifth year, then very slowly; the growth
after twenty is very slight. Cromwell's brain is said to
have weighed almost eighty ounces. Other great men
have had large brains, but some great minds have inhab-
ited very small brains. Quality is as important as quantity.
The brains of idiots are usually very small.

559. The Parts of the Brain are the cerebrum, cerebellum
and cerebral ganglia. The cerebrum, or great brain, is
highest in the skull, and covers all the other parts ; man
is the only animal of which this is true (Plate VI).
Sense-perception, consciousness, reason, and the will are
located in the cerebrum.

The cerebellum, or small brain, is at the base of the
skull behind. If a pigeon has its cerebellum removed,
it is restless and has wide-open eyes ; it flutters, but can-
not fly. If the cerebrum is removed, leaving the cere-
bellum, it is stupid, but flies if thrown into the air. By
placing the hand at the back of the skull between the
occiput and the neck, you will cover the part occupied by
the cerebellum. Coordination of the muscles is believed
to be carried out by the cerebellum. You will to walk

302 ELEMENTS OF PHYSIOLOGY

through activity of the cerebrum; the control of the
muscles while walking is the function of the cerebellum.

The cerebrum and cerebellum, like the spinal cord, are
divided by deep clefts into hemispheres. The cerebral
ganglia are in the lower central region of the cavity (see
Plate VII).

560, The Medulla Oblongata. — This, the most important
of the cerebral ganglia, is sometimes called the spinal
bulb. It may be looked upon as the part of the spinal
cord within the skull. It is just within the foramen mag-
num, and is intermediate in position and function between
the brain and spinal cord. The spinal cord acts reflexly ;
the brain acts consciously. Conscious actions are those
which are influenced by mental images or ideas. The
medulla contains reflex centers and the centers of auto-
matic action. This kind of action should not be confused
with acquired reflexes, such as walking, to which the term
automatic is sometimes applied. Automatic centers are
those which are controlled by the condition of the blood.
They are stimulated by an increase of carbon dioxid in
the blood. The chief of these centers is the respiratory
center of the medulla. If it is injured, death ensues by
suffocation. It is sometimes called the vital knot, because,
although the cerebellum or even the cerebrum may be
injured or removed from the lower animals without causing
death, the smallest injury to the respiratory center kills
the animal immediately. In cases of hanging, it is injury
to this center that causes death. Another very important
center in the medulla, controlled by automatic action, that
is, by the varying condition of the blood, is the center for
vasomotor nerves, which regulate the size of the blood
vessels. It was previously learned that the vasomotor
fibers belong to the sympathetic system. There are also
important reflex centers in the medulla, viz., the centers
for the secretion of saliva, for swallowing, for vomiting.

THE NERVOUS SYSTEM

303

561. How Automatic Centers work. — As the blood be-
comes deficient in oxygen and charged with carbon dioxid,
the respiratory center is irritated and sends out im-
pulses which cause deeper breathing. This improves the
condition of the blood, and the respiration is quieter until
the blood again loses oxygen; then stronger impulses are

Face Sensory -j —

Face Motion

Taste

- Spinal Cord
1st Spinal Nerve
2d Spinal Nerve

FIG. 201. — Diagram of the Twelve Cranial Nerves.

There are twelve pairs of cranial nerves which arise from the brain and go out through holes
in the lower wall of the skull. (How many pairs of spinal nerves are there ? ) The cranial
nerves are numbered, according to the location of their roots, from above downward.

sent, and so on, thus regulating the condition of the blood
automatically. The size of the blood vessels is regulated
in the same way by the vasomotor center in the medulla,
increase of carbon dioxid causing contraction of the sur-
face vessels, decrease of it causing relaxation. Automatic
acts take place in series. Reflex acts, as for example,

304

ELEMENTS OF PHYSIOLOGY

walking, can take place in series also, but the first stimulus
in reflex acts comes from without the body ; in automatic
acts from the blood.

FUNCTIONS OF THE CEREBRUM

562. " There was once a man who, holding out a piece
of his own skull, begged for money in the streets of Paris.

The upper portion of the vault
of his skull had been torn off by
an accident, and his brain was
protected only by the strong
fibrous covering of the dura ma-
ter. The wound otherwise was
healed, and the man strong and
well. Now for a small sum the
beggar would allow any one to
press upon his brain, and when
this was done he lost conscious-
ness, and, as it were, fell into a
deep sleep. But when the pres-
sure was withdrawn, conscious-
ness returned, and the man
awoke. So soon as the blood
was squeezed out of the cerebral
hemispheres, these organs ceased
to work and consciousness van-
ished " (Hill). If the blood
vessels of the neck are com-

FIG. 202. -A Sketch to show how pressed SQ as to cut off the Qxy.

One Set of Nerves takes Messages •

gen from the brain, a person
becomes unconscious. If the
heart suddenly weakens its ac-
tion very much, or if the vaso-
motor nerves allow the arteries to lose tone suddenly and
increase their capacity for blood, the person faints, from a

to Certain Centers in the Brain,
and how Another Set of Nerves
carries Orders from these Brain
Centers to the Mouth, the Hand,
etc.

THE NERVOUS SYSTEM 305

weakening of the circulation through the brain. Recovery
is brought about by placing the head on a lower level than
the body, so that the blood may run to the brain with less
exertion on the part of the heart. A violent blow on the
head may make one insensible at once. By breathing chlo-
roform, ether, or carbon dioxid, by taking morphine, the
quality of the blood may be so altered as to bring sleep. In
order that the brain may act, it must be con-
stantly aroused by impulses from the outer
world. There is a case reported of a man
all of whose sensory nerves had lost sen-
sibility except in one eye and one ear. He
fell asleep immediately if the . remaining
sense organs were closed. The conclusion
to be drawn from the foregoing facts is,
that a man loses consciousness so soon as
his cerebral hemispheres cease to act ; but

his heart and lungs keep at work. It is _

FIG. 203. — Micro-

curious that touching the cerebrum, or scopic Diagram of
stimulating it with electricity, when it has cJ^^J^Jj
been exposed by accident, arouses no sen- Brain.
sation, although this organ is believed to A, external layer of as-

. . . . ,_,. . .. . sociation cells, axons,

be the seat of consciousness. This fact is anddendrons; B, Py-

of great interest, for it shows that impres-

sions coming from the sense organs alone the layfir of medul-

lated fibers C. The

enter into consciousness. dendrons of the Py-

563. Effect of removing Cerebrum. — la™^"11
After destruction of the cerebrum, an ani-
mal may continue to live if fed by hand. It can run about,
and swallow food placed within its mouth. It will be dis-
turbed by a loud sound, such as the blowing of a horn.
It might avoid a bright flame if placed in its path, but would
go stupidly against other objects ; but it is idiotic, for all
acts of intelligence cease. Its time is spent in sleep or
mechanical wandering. A frog having its cerebrum re-

306

ELEMENTS OF PHYSIOLOGY

C. Motor. By
which we move

B. Sensory. By
which we feel.

little Brain or
Cerebellum.

FIG. 204. — The Area A has not
been as definitely located as the
Areas B and C.

its back, swims when
thrown into water, and
when placed on a board
that is slowly tilted, it
will preserve its balance
by climbing to the top.
These actions are reflex

Marrow
edulla.

A. Intellectual. rnr»ir^r1
By which we think "lOVea

some more ex-
tensive powers
than a warm-
blooded ani-
mal. It starts
to hopping
when touched,
avoids obsta-
cles in its path,
recovers its
usual position
when placed on

FIG. 206. — View of One Cerebral Hemisphere from
between the .Hemispheres, showing Motor and
Sensory Centres.

FIG. 205. — Motor and Sensory
Centers. Most Centers occur
in Both Hemispheres, and if
One is injured, the Other will
continue to work.

but of a higher or-
der than a simple re-
flex act. The reason
the frog continues
hopping after being

THE NERVOUS SYSTEM 307

touched is that each hop, owing to the contact of the skin
with the ground, excites another hop ; the animal never
begins to move of its own accord.

564. Function of the Cerebellum. — The removal of the
whole of the cerebellum from an animal does not produce
death so long as the medulla is not injured, but the animal
becomes weak and unsteady in its movements. If the
cerebrum remains, the mental faculties are retained. Dis-
ease of the cerebellum in man produces dizziness and leads
to a staggering, reeling gate. Hence it is believed that
the function of the cerebellum is to aid the cerebrum in
the control of the muscles. It brings about proper co-
ordination of the muscular movements, so that in such
movements as standing, walking, talking, the different
muscles may each act at the right moment and with due
force. The spinal cord also coordinates movements. For
instance, if a frog is decapitated and left quiet for an hour
or two, so that the spinal cord may recover from the shock
due to the injury, it may be made to execute 'seemingly
purposeful movements. If a drop of acid be placed on the
flank of such a frog, the>leg will be drawn up and the acid
wiped off with the toes. But such coordinated move-
ments are not accompanied by consciousness.

565. The Motor Area in the Brain (Figs. 204, 205, 206).
— A wounded soldier was brought to the surgeons of the
German army with part of his skull torn away. The sur-
geons used an electric current to test whether the nerves
were paralyzed. They were astonished by finding that
whenever the electric current was applied to the wounded
part of the head, muscular movements were excited. It
was soon determined that by stimulating electrically a cer-
tain area of the cerebral cortex movements on the opposite
side, of the body can be excited. This area lies under the
parietal bone, and extends from the top of the brain to
the level of the ear. By experiments on monkeys and

308

ELEMENTS OF PHYSIOLOGY

dogs, and by studying cases of accidents to the skull in
human beings, this area has been subdivided. Stimulation
of the lowest part causes movements of the face ; of the
middle part, the arm ; and of the upper part, the leg, the

FiG. 207. — Diagram of the Motor Area and the Motor Tract in the Brain.

Find centers for leg, arm, face. Notice that most of the motor fibers from one hemisphere
cross to the opposite side of the spinal cord; and if one half of the brain is injured the
opposite half of the body loses motion and sensation (paralysis).

Trace nerve impulse from cell in cortex at i to muscle at 7.

Trace reflex impulse from skin at « to muscle at 7.

movement always being on the side opposite to the stimu-
lation. When the lowest part of the area on the left side

THE NERVOUS SYSTEM 309

in right-handed persons is injured, the power of speech is
lost. The comprehension of words and the ability to write,
read, and hear language is not lost. With left-handed per-
sons, this center is on the right side.

566. Other Centers in the Cerebrum (Figs. 205, 206).-
When the part of the cerebrum that lies behind the ear is
destroyed, a loss of the memory

for the meaning of words may
result. One can speak, but his

words follow each other without .^.^^Auw^^gu A
sense or meaning. The sense of " •&*=*

hearing is supposed to be located
in the same region. The sense of
sight is located in the rear part of
the cerebrum. If the rear part
of the left hemisphere is de-
stroyed, a man is unable to see
anything to the right of his nose

when his eyes are directed straight FlG- 208.— The Olfactory Nerve,
forward. The sense of smell lies The main nerve ends in the form of a

bulb on the floor of the skull. The

at the base of the cerebrum toward fibers branch from this buib like the

,1 r 4. /T7' ,^/c\ roots from an onion and spread out

the tront (1< ig. 206). on the walls of the nasal chamber.

HYGIENE OF THE NERVOUS SYSTEM

567. Sleep. — The cells of the body with all their
industry are not tireless, and at intervals require rest
(Fig. 210). During sleep the heart beats more slowly,
respiration is less rapid, the muscles in general are re-
laxed, the gland cells diminish their secretions, and diges-
tion is slow. The production of heat is lessened and the
body must be protected from cold. Yet consciousness is
the only function entirely in abeyance. The sound of a
passing vehicle quickens the pulse of the sleeper with-
out awaking him; if he is touched, he moves. Sleep
is deepest during the second hour, and it then takes a

310 ELEMENTS OF PHYSIOLOGY

much louder sound to awaken him than during later hours.
Sleep becomes gradually lighter until awakening occurs.
When consciousness is partly awake, the condition is
called dreaming. In somnambulism, the sleeper may talk
or walk as he dreams.

568. For a sound nervous system, nothing is so indis-
pensable as plenty of sound sleep. It is necessary .for
growth and repair of the cells (Fig. 210). Infants sleep
almost all the time ; children of four or five, nearly half the
time ; those of ten or twelve, ten hours ; most college

FIG. 209.

A, auditory center; B, visual center; C, speech center; D, motor cells of speech nerves in the
spinal bulb. Sight of dog, bark of dog, word " dog " and sensations from speech muscles are
represented by arrows passing into the brain. The centers are connected by association
fibers, so that when the child has learned the word "dog" by sound or when written, the
spoken or written word calls up the image, the sound of its bark and the muscular
memory of how to speak the word " dog. "

students require eight hours, and this amount is required
by most adults until old age is reached. Repair being less
in old age, less sleep is required.

569. The morning should bring a feeling of vigor. If
we wake tired and discouraged, there is something amiss.
It may be that there was over-exertion the day before and
the sleep has not been long enough, or that we have been
up too late or have eaten improper things. If the last is
the case, there is apt to be a bad taste in the mouth on
awakening. By going to bed at the same hour every
night, the habit is formed of dropping off promptly and
soundly to sleep. A cheerful state of mind with resolute

THE NERVOUS SYSTEM

avoidance of worry promotes sound sleep at night. The
sleeping room should be cool, but it is not necessary that
water freeze in the pitcher. It
should be well ventilated, a win-
dow being left partly open even
in moderately cold weather in the
northern states, and in very cold
weather in the Gulf states, unless
the room is loosely built.

570. Effect of Activity of Nerv-
ous System. — If the cells of any
tissues are not active, they become
weakened. It is the same with
the nervous system. Fresh and
new sensations are necessary for
the health of the brain ; those
mental faculties that are used be-
come strong. Unused muscles FIG. 210.— A study of Fatigue.

flabby and ill-nourished Portions of nerve cells from the spinal

ganglia. A, resting cell. £, cell

because the circulation in them

from a ganglion that had been elec-
trically eliminated for five hours.
The shrinkage of the nucleus and
structure of the fatigued cell is
marked.

is weakened ; the circulation in
inactive nervous tissue also be-
comes less active. Mental activity
strengthens the nervous system and the body in general.
If one protects his sensory nerves by too warm clothing
and never lets the cold air strike them, they become weak-
ened and unreliable and allow the blood vessels to lose
tone. They are likely to do strange things with the
circulation, causing colds and disease. If, because of
pulpy or soft food, the nerves of the alimentary canal are
not stimulated mechanically, peristalsis is weakened and
the intestine becomes clogged. The loss of tone in the
circulation and the sluggish peristalsis, with the troubles
that follow, can often be cured by taking a cold bath every
morning. The stimulus to the sensory nerves spreads

312 ELEMENTS OF PHYSIOLOGY

reflexly to the vasomotor nerves and to the sympathetic
fibers of the intestine ; these are " toned up " and restore
activity to the involuntary muscles.

571. Connection of Body with Brain and Mind. — The
pulse rate is affected by every emotion. Shame causes
the blood vessels of the face to dilate. Painful emotions
excite the activity of the lachrymal or tear glands. Joy
increases ease of movement. If an excited or angry man
who is walking to and fro sits down, his excitement de-
creases. A starving man and one suffering from fever
have hallucinations. The Romans had the proverb " a
sound mind in a sound body." The care of the body for
the mental effect as well as for the sake of the body itself,
is only gradually regaining the high place it held among
the Greeks and the Romans, a place which it lost dur-
ing the Dark Ages. " Hysteria and nervous exhaustion
are the fruits not of overwork, but of lack of varied and
interesting employment. The absurd opinion that hard
work is menial and low, leads to most pernicious conse-
quences. The girl who, turning from brain work to
manual labor, can cook, scrub, wash, and garden, invites
the bloom of health to her cheeks ; while the fine do-
nothing lady loses her good looks, suffers from the blues,
and is a nuisance to her friends and a misery to herself."

572. Two Kinds of Tired Feeling. — if a person works
hard mentally or physically, the nutrition stored in his
cells is consumed by the oxygen. Carbon dioxid, urea,
and other products of oxidation, accumulate ; this decreases
the production of heat, smothers the vital fire, as it were,
and stops the setting free of energy. The muscles may
ache with fatigue or the brain grow drowsy; this is the
natural and healthful kind of tired feeling. It leads to rest
and recuperation. During the interval of rest, even if no
new food is absorbed from the canal, digested food, already
in the blood, and lymph are built up into living tissue again,

THE NERVOUS SYSTEM 313

a process called assimilation. But suppose one does not
work, but is idle, or suppose one works with only a small
part of his bodily organs and forces the other organs to
loaf; the oxidation in the cells does not take place com-
pletely. Instead of urea, uric acid and other poisonous
products of incomplete oxidation result. These poisons
circulated by the blood to the nerves can give them a tired
feeling as effectually as hard work. Often with inactive,
idle persons the digestion also becomes sluggish, fermenta-
tion takes place and the food is changed to poisons. These
additional poisons are absorbed by the blood and carried to
the nerves to increase further the tired feeling. Some per-
sons never work, yet are always tired and are said to have
been "born tired." They belong to this second class. If
they did some honest^ vigorous work for a few days, it would
lead them to breathe deeply and freely and burn up this
refuse material. They would again have that self-confident,
buoyant feeling that all men may have and that every man
that takes care of his body does have.

573. The Source of Pain not always where it seems to be.
— When the " funny bone" is hit, the tingling is referred
to the finger, although, of course, the pain is in neither
the funny bone nor the finger, but in the brain. If the
scar grows too tight over the stump of an amputated arm,
the itching that seems to be in the fingers may not stop
until the scar is opened by a new cut, and the tightness,
which is the source of the pain, is removed. Some forms
of neuralgic pains and headaches appear to travel quickly
from one part of the face to another. This is because the
source of the trouble is not in the face at all, but in the
medulla. Bad headaches are not so often neuralgic as
from other causes (Fig. 211). When the spine is habitually
held crooked, or, in rare cases, some of the vertebrae are
displaced by a fall or jar, the circulation may be interfered
with near the roots of the spinal nerves, and give the feel.-

314

ELEMENTS OF PHYSIOLOGY

OiSTUfiBANCES OF
ftOSE EAR. AND
OCCAYfD T££TH

—SPINAL (MITA7IQH

FIG. 2ii.— The Situations of Headaches with
Relation to their Causes.

Neuralgic headaches (not marked) are believed to
arise from congestion in the nerve centers.

ing of pain in various places in the body where the nerves
terminate ; for " pain is the cry of a starved nerve for

fresh blood or better
blood." The reason the
mind always refers the
pain to the end of the
nerve is that nearly all
.-MEWSES EXHAUSTION pain from a nerve does
come from some irrita-
tion at the end of the
nerve, and the mind re-
flexly, as it were, inter-
prets the pain as coming
from its usual source.
When the position is cor-
rected, the circulation is
freed and relieves the
nervous system. Downward displacement
of the abdominal organs may cause pressure
upon some of the sympathetic nerves and
ganglia and cause pain and derangement of
different organs. What causes the foot to
"go to sleep"? Can you explain the self-
deception in " Aristotle's experiment " (Fig.
212)?

574. Effects of Alcohol on the Nervous Sys-
tem. — As alcohol acts on many organs
through its action on the nervous system,
it would naturally be supposed that the nerv-
ous matter itself would be injured, and such
is the case. In fact, it is upon the delicate
nervous system that its most destructive ef-
fects are wrought. One of the first effects of
alcohol is a flushing of the face and a feeling

& FIG. 212. — Aristotle's

of warmth on the surface of the body. This Experiment.

THE NERVOUS SYSTEM 315

is due to the quickened action of the heart and the dilatation
of the small blood vessels from the effects of alcohol on the
nerve centers controlling these organs. The mind is at first
more active, because the little vessels of the brain are dilated
and blood is sent more freely to that part. A little later the
alcohol begins to disturb the reflex and coordinating powers
of the nervous system, and ordinary muscular movements
are performed imperfectly and with difficulty. The nerve
centers seem to be attacked and paralyzed progressively
by alcohol, beginning with the highest and proceeding
toward the lowest. The will power and judgment first
become paralyzed, and only the emotional and impulsive
instincts of human nature are left ; these, being no longer
under control of the higher faculties of reason and
judgment, are likely to cause the individual to act in an
irrational manner. In the last stages, consciousness and
volition are lost, and only that part of the nervous system
in the medulla which governs circulation and respiration
remains active. In other words, the man is " dead drunk."
A large quantity of alcohol may produce death by paralyz-
ing even these nerve centers, thus stopping all organic
functions. This overaction and irregular action of the
nerves, when repeatedly occurring, has the effect finally
of deforming or destroying the nerve tissues (Fig. 191).
575. There is scarcely a nervous disease known to
science that the use of alcoholic liquors may not bring on
or aggravate. General debility, neuralgia, insomnia, epi-
lepsy, paralysis of every form and type, insanity in all
its grades, as well as delirium tremens, may find in alcohol
their exciting and predisposing cause. But the worst of all
of the effects of its long-continued use is upon the morals.
The brain degenerates and the mind loses control over the
appetite. Pledges of total abstinence, fear of disgrace,
loss of social position, loss of friends and family, apprehen-
sions for this world or the next, — all these considerations

316 ELEMENTS OF PHYSIOLOGY

have no more weight against this disease of chronic alco-
holism, than they would have against smallpox or typhoid
fever.

576. Subjects for Compositions. — Prevention better than
Cure. Habits. Sunshine. Natural Cures and Medicines.
The Influence of the Digestive Organs upon the Other
Organs. The Influence of the Muscles upon the Other
Organs. The Influence of the Blood upon the Body. The
Influence of the Nervous System upon the Other Organs.
Heredity. The Causes of Disease. The Rewards of
Right Living. The Influence of the Body upon the Mind.
The Body a Temple. Housekeeping. The Way of the
Transgressor is Hard. Nature as a Physician. Health
and the Disposition. The Mind and Health. Wonders
of the Body. Mysteries of the Body. What Fools these
Mortals Be. Health Fads. Medicine Crazes. Exposure
and Coddling. Pampering and Hardening. The Blessings
of Temperance. Effects of Use. Effects of Disuse.
Why are we Sick ? Adam's Apothecary Shop.

577- Phrenology. — There is a fantastic theory called phrenology
that young people should learn to estimate correctly. It is based on
dividing the head by guesswork into sections supposed to be the seats
of the various attributes of the mind, such as firmness, benevolence,
self-esteem, acquisitiveness, and what not. This attempt at science
was made over a century ago, and it has been known for a hundred
years to be nonsense. But it is turned to financial profit by charlatans,
who take advantage of the unlearned seeking a short cut to science.
Bumps on the head, instead of indicating the presence in the brain of
more gray matter, are due in many places to thickening of the bone, or
to air spaces in the bone. Phrenology belongs in the realm of ex-
ploded sciences along with astrology, or reading one's future in the
stars ; palmistry, or telling the fortune by reading the lines in the hand ;
and alchemy, or the search for the philosopher's stone, which was to
turn everything it touched into gold.

578- Hypnotism, etc. — Even when awake our actions are largely
controlled by the suggestions or influence of others. Although we are
awake, this influence is largely unconscious. But if one goes to sleep

THE NERVOUS SYSTEM

at the suggestion of another and while hearing his voice and believing
in his power to influence, the subjection to that influence continues
during the sleep which follows. This sleep seems to be a kind of
induced somnambulism. That there is no animal magnetism concerned
is shown by the fact that the most delicate electrical instruments fail to
show the faintest disturbance. Frequent repetition of the hypnotic con-
dition is believed by some to weaken the will of the individual. The
nature of the hypnotic condition is not fully settled. Like other sub-
jects on which science is unable to pronounce a definite verdict, this
whole subject has been surrounded by rogues with humbuggery and
quackery. Some persons by practice can read the intended movements
of another by grasping the hand of the other with his arm held in an
unstable position. This muscle-reading is based upon the fact that
when the mind is concentrated on making a certain movement, the
muscles will resist an opposite movement. Again, the mystery of
ordinary sleep has never been solved. It is not surprising that its
variations, such as trances, somnambulism, and the hypnotic sleep, are
not understood. The relation of mind and matter, the connection of
the soul and body, are mysteries that may be beyond the power of man
ever to solve.

APPLIED PHYSIOLOGY
EXERCISE I

1. Why is playing the organ less trying to the nerves of the
player than playing the piano?

2. Why is it best to change from very absorbing work to work
of less interest a while before retiring ?

3. Why is the power of habit a blessing? A danger?

4. How does travel often cure a sick person when all else fails?

5. Why should we never study immediately after eating?

6. Why is working more healthful than " taking exercise " ?

7. Is it better for children to play or to take exercise?

8. What causes the peristaltic action of the stomach?

9. Is one more likely to sleep soundly who does his brain work
in the forenoon and muscular work in the afternoon than if he
reverses the order?

10. Why can one walk and carry on a conversation at the same
time?

EXERCISE II

11. How does indigestion cause a headache?

12. Does perfectly comfortable clothing from head to foot contribute
to one's ease in company?

318 ELEMENTS OF PHYSIOLOGY

13. Does uncomfortable clothing make one self-conscious?

14. Is it as important to have the shoes and the clothing perfectly
comfortable when going out as when staying at home?

15. Would you get more rest by sleeping for four hours undisturbed,
or by sleeping eight hours but being awakened every half hour by some
noise and going immediately to sleep again (§ 567) ?

1 6. When one sits with the leg,under the body, why is it that the
compression causes a tingling sensation or paralyzed feeling in the foot ?

17. When one's finger is cut, where is the pain?

18. Why does a hand still seem to itch after it is amputated?

19. Does the act of assuming artificial positions like the "straight-
front" tend to make one stiff or graceful, self-conscious or spontaneous?

20. Do the girl who frets over washing the dishes, working with an
unwilling mind, and the boy who, while he is sawing wood, is wishing
to go to a baseball game, do their work with more or less fatigue than
if they worked cheerfully and willingly ? Why?

EXERCISE III

21. How is a sneeze a protective act ?

22. Why may a dyspeptic digest a large Thanksgiving or Christ-
mas dinner when he often has trouble with an ordinary dinner?

23. Why is it more difficult for an adult to learn to speak a language
than for a child? Why do adults find drawing and languages more
difficult to acquire than history and mathematics (§ 546)?

24. In what two ways may opening a window when a student is
becoming dull and drowsy at his books enable him to wake up and
study with ease?

25. What is the basis of the saying among mothers that a " croupy "
child can be cured of the tendency by being allowed to go barefoot a
great deal ?

26. Did you ever know any person to whom the terms "afflicted by
the disease of work" applied? Also the opposite, " disease of idleness"?

27. Muscles may be classed as minor, such as those of the eye,
voice, hand ; and major, such as those of upper arm, leg, trunk. Why
is the use of the minor muscles exhausting to the nerves, while the use
of the major muscles strengthens the nerves (§§ 227, 234) ?

28. What kind of cells shrivel like a baked apple when they become
fatigued (Fig. 210) ?

29. A nerve or nerve fiber does not become tired or fatigued in any
way. What do we mean when we say the nerves are worn out
(Fig. 210)?

THE NERVOUS SYSTEM 319

30. Why do you throw cold water upon a fainting person?

31. Nightmares are caused by poor circulation of the blood about
the solar plexus, which is just behind the stomach. Explain how sleep-
ing on the back may bring them on. How eating a heavy supper may
cause them.

32. What is the effect of a thin skin and of a thick skin upon the
disposition of a person ?

33. Why may cold feet cause sleeplessness?

34. Why does constant moderate drinking undermine the health
more than occasional intoxication?

35. The vasomotor nerves control the size of the blood vessels.
Which nerve centers control these nerves ? Why does a draught blow-
ing on the back of the neck often cause a cold (Fig. 200) ?

CHAPTER XVII

SOME SPECIAL REGULATIVE PROCESSES

REGULATION OF TEMPERATURE

579. Necessity for Regulation. — Man lives in the torrid
zone and in the frigid zone, yet his temperature remains
the same as he goes from one zone to another, and as
summer changes to winter. The temperature of the
healthy body is about 98.6° F. This is unmistakable
evidence that some means of maintaining a uniform
temperature exists in his body. The wonderful ease
with which the human body maintains a normal tempera-
ture when exposed to extremes of heat and cold is a fasci-
nating and instructive subject for study; but it remains
partly a mystery, and the mechanism by which this end is
attained has never been fully explained.

580. The Highest Temperature which living tissue may
reach without destroying life is 113° F., but it could remain
at such a temperature only a short time.1 "A man can
for a short time remain in an oven heated to the boil-
ing point of water (212° F.), provided the air is dry. With
felt slippers on his feet he could stand there while his dinner
cooked beside him. He is able to do this owing to the pro-
fuse perspiration which pours from his skin and cools his
body by evaporation. If the oven were full of steam, the

1 Once a man took the pulse of his daughter who was ill, and found it to be
1 20. He was greatly alarmed, and summoned several physicians. He had
confused the pulse with the temperature. The pulse rate during vigorous
exercise sometimes reaches 160 per minute.

320

SOME SPECIAL REGULATIVE PROCESSES $21

man would be instantly killed, because evaporation of the
sweat would be prevented" (Leonard Hill, M. D.). If
the cells of either plant or animal life be subjected to a
temperature of 114° or over, the life of the protoplasm is
destroyed beyond recovery.

581. Breathing and the Temperature. — Since oxygen is
the supporter of combustion and carbon dioxid retards
combustion, the quantity of oxygen and carbon dioxid in
the body affects the temperature. When the body is at
an abnormally high temperature, as during a fever, the
breathing is generally more vigorous than usual. Those
animals, such as the bat, that hibernate and go without food
in cold weather, cease breathing altogether during the
trancelike condition, and their temperature sinks nearly to
freezing point. The absence of the oxygen, other than
what may diffuse through the windpipe into the motionless
lungs or through the skin, and the accumulation of carbon
dioxid, cause the fire of life to sink very low.

582. The Source of Animal Heat is the combustion of the
food in the body by the oxygen. Wherever cell activity
is taking place, heat is produced. The muscles are the
greatest heat producers of all the organs. Their activity
gives rise to one half the heat of the body. A frog's body
keeps at the temperature of the surrounding objects in
winter and summer. He cannot stand the heat of summer
and retires to a cool ditch or well. In winter he buries
himself to escape the cold. He is stimulated by warmth
and benumbed by cold. Man and other warm-blooded
animals, on the contrary, are stimulated by cold and are
less active during warm weather. The temperature of
birds is 104°. A chick before hatching is like a cold-
blooded animal. As soon as it begins to peck its way out
of the shell, it begins to acquire the power of regulating
its temperature ; the power may be acquired in a few
minutes. This new power comes from the new muscular

Y

322 ELEMENTS OF PHYSIOLOGY

activity of the chick, the beginning of the habit of breath-
ing, and the drying of its downy feathers.

583. The Loss of Heat occurs by conduction through the
skin, also by the evaporation of water from the skin and
lungs, and by the taking in of cool food, drink, and air.

584. How the Nerves regulate the Heat. — The tempera-
ture of the body is raised by increasing the heat produc-
tion, or by diminishing the loss of heat. The temperature
is lowered by the opposite processes. There are believed
to be three classes of nerve centers to regulate the pro-
cesses. One class of centers in the brain when stimulated
by cold causes the heat production to increase ; another
class when stimulated, causes heat production to diminish.
The third center is in the spinal cord and is automatic, but
may be influenced by the centers in the brain. We should
be in danger of being killed by the cold long before the
thermometer reached the freezing-point, if it were not true
that cold, in whatever form it may be applied, starts im-
pulses in the skin which excite the tissues that generate
heat, so that there is increased production of heat.

585. The Distributor of Heat generated by the active
organs, to the resting organs, is the blood. The blood
also causes heat to leave the body, giving it off while pass-
ing through the blood vessels of the skin.

586. How does perspiration cool the body ? Why is it
an advantage for you to shiver and for your teeth to
chatter when you are very cold ? Why is it an advantage
for the skin to turn pale when one goes out into a cold
wind ? What effect upon perspiration does the blanching
of the skin have ? What effect does the blanching have
upon the loss of the heat of the body from the contact
with the cold air ?

587. Clothing conserves the heat of the body, but cannot
generate it. Such heat arises from the combustion in the
system of the food by the oxygen of the air. In hot

SOME SPECIAL REGULATIVE PROCESSES 323

weather the body naturally requires less heat than in colder
seasons; hence less food, especially fats and sugars, are
consumed in summer than in winter, in the tropics than in
temperate or frigid regions. Suppose you have changed
your clothing in summer to the very coolest, and are still
oppressed by the heat, what changes should you make in
your diet ? Suitable food eaten in moderation adds
greatly to one's comfort in warm weather, and enables
one to work with energy and pleasure, but partaking
abundantly of heating foods renders all exertion dis-
agreeable.

REGULATION OF THE STORE OF ENERGY

588. Fatigue. — You learned in the chapter on stimu-
lants and narcotics that a man has energy stored up suffi-
cient to support him for a certain number of days without
food. (How many days ?) Stored energy is simply a
store of food and oxygen in the tissues. The nervous sys-
tem so acts as to prevent any undue exhaustion of that
supply from taking place. When the brain is long active,
fatigue and sleepiness ensue. When the muscles are long
active, fatigue and aching ensue. The wise person rests
in each case. These warnings come before the exhaus-
tion has progressed to an injurious degree. They are
caused by the accumulation of the products of combustion
in the tissues. These products affect the nerves and the
warning is thus given.

589. In what other way besides by work may poisons
accumulate so as to cause a feeling of exhaustion and lack
of energy ? What are the two kinds of tired feeling of
which you learned ? Has a person any more right to
injure his own body or allow diseased conditions to come
to it than he has to injure the body of another ?

590. Improvidence. — Just as there are many persons who
cannot keep financial capital ahead sufficient for one

324 ELEMENTS OF PHYSIOLOGY

month's needs, so there are many people who cannot keep
physical capital in their bodies sufficient for forty days
ahead. This is the amount that every sound person
should have. They expend their energy until they are
"worn out" temporarily, or they neglect proper care of
their bodies so that the mechanism does not work properly,
their energy is diminished, and they become depressed.
When one is depressed and exhausted from overwork
or improper working of the physical organism, his first
care should be to restore the strength. Rest will often
accomplish it, but many persons are not wise enough to
observe this ; they have a mistaken notion of the nature of
stimulants and of the bodily strength. They arouse the
nerves to renewed action by taking poisons; activity
ensues that leads to expenditure of a part of the precious
strength remaining. A drunkard during a period of in-
toxication often keeps up this course until his strength is
exhausted. He is physically bankrupt; then he stops.
After a few weeks or months of soberness, during which the
organs have stored up energy again, he begins to apply
poisonous stimulants to enable him to use up this strength
and becomes physically bankrupt again, thus proving him-
self unworthy to have as much capital intrusted to him as
is intrusted to other men.

591. Are Feelings always a Reliable Guide ? — Feelings
may be deceptive, not only when the nerves are confused
by stimulants, but also as the result of bad habits. A man
who has stooped over a book or desk all day does not feel
like doing muscular work, yet it is the very thing he needs
to expand those flattened lungs that brought the feeling of
fatigue. If one habitually overeats, it may cause a gnaw-
ing at the stomach that gives him a desire to continue
the habit. After using alcohol or tobacco, a desire for
these worst enemies of the body is implanted. The body
seems to acquire injurious habits and desires almost as

SOME SPECIAL REGULATIVE PROCESSES 325

readily as healthy ones. The warnings against destructive
acts come at first. If the warnings are disregarded, natural
instincts, those heaven-sent guardians of our welfare, with-
draw, and evil habits and desires assume control.

592. Natural and Artificial. — Everything in the world is
natural. We and our most artificial acts are a part of
nature. That which comes by nature apart from man, or
that which he does truthfully copying nature, is usually
called natural. That which is done by man in such a way
as to disregard the usual processes of the rest of the
natural world, is called artificial. Artificiality is usually
marked by ugliness and weakness, but it is not recognized
as such by any one whose taste has become depraved from
following artificial customs.

DISEASE

593. Use of Pain and Disease. — Most diseases have for
their purpose to repair, to protect, or to purify. If the
body can set to work to repair a cut in the flesh or a
broken bone, how much more easily can it purify unsound
organs or tissues and make them sound again. It used to
be the custom to apply liniments and healing ointments
to wounds and broken bones to assist in the healing, but
now it is found that to set the bone and bind the edges of
the wound together is sufficient. If kept clean and undis-
turbed, nature will work a perfect cure.

594. Sometimes Poisons accumulate in the body and in-
terfere with the working of the organs. This may be
caused by drinking poisonous substances, or using them as
food, or by indigestion, in which case germs may find sus-
tenance and multiply, giving poisons into the circulation.
The automatic regulative apparatus of the body is usually
equal to the difficulty. These poisons are oxidizable, es-
pecially at a little higher temperature than that which the

326 ELEMENTS OF PHYSIOLOGY

body usually has. So nature sets to work to create more
heat in the body and literally to burn up the poisons. If
the impurities are in one place, as in a joint or in the
throat, there arises local heat, called inflammation. If the
poisons are distributed in the body, a more general heat,
called a fever, may begin.

Fever in itself is harmless and should not be combated
unless very high and of long duration, under which con-
ditions it may destroy the tissues. Fever is nature's method
of ridding the body of poisons which, if allowed to accumu-
late indefinitely, may produce death or permanent weak-
ness. One who has fever should avoid using strong
remedies to lower the temperature, unless the fire that
is burning up the rubbish threatens to destroy the house
also. While a fever is in progress, nature takes away
the appetite to prevent adding fuel to the flame; takes
away the inclination to move, as the exercise would be
carried on by combustion in the muscles ; gives great
thirst for cold water, which cools the body and dissolves
the poisons, and adds to the activity of the kidneys in ex-
creting the products of the combustion. In former days,
when nature was entirely distrusted, a patient burning
with fever was not allowed a drink of cold water, as it was
supposed it would kill him. (Read notes I and 2, page

329.)

595. If a grain of sand gets into the eye, nature first
causes pain to prevent winking the lid and injuring the eye,
and then produces tears which tend to wash out the sand.

If a boy eats green apples, he has colic, which should
teach him to wait next time until they are ripe. He
has taken indigestible things into his stomach, and the
stomach, acting for his welfare, under the direction of the
nervous system, ejects the food. When a person habitually
partakes of things which are irritating to the stomach and
injurious to its delicate lining, nature creates mucus to

SOME SPECIAL REGULATIVE PROCESSES $2?

lubricate or oil the lining, so that the mucous membrane
may not suffer serious damage. In this way arises catarrh
of the stomach, which is very disagreeable, but is a pro-
tective and curative process.

596. A man has painful gout in a joint; what is the
matter ? The man did not burn up by honest muscular
work the food he ate, and it turned into poisonous acid,
which collected in the loose spaces around the joint. The
natural regulative power of the body forces that man to
rest, by sending a pain every time he moves actively, in
order to prevent damaging the joint by moving it too
much while the inflammation is burning up the poison. If
the man were allowed to exert himself actively, uncon-
scious of the damage, the joint would soon be destroyed.
(Read note 3, page 330.)

597. Indigestion is another trouble that is usually mis-
understood. If one suffers from "biliousness," the liver
is at once blamed, when usually the liver has nothing to
do with it. You learned that the condition, as a rule, re-
sults from taking food into the stomach out of all propor-
tion to the work its owner does ; or, in warm spring
weather, from eating enough to keep one warm in freezing
weather. Then follows a combination of symptoms which,
at a guess, is called biliousness, — loss of appetite, nausea,
headache, loss of energy. The first symptom is sent be-
cause nature insists on giving the stomach a rest when it
is incapable of digesting ; the nausea may produce vomit-
ing to expel the offending substance. The headache and
loss of energy are to prevent exercise that would stir up
the circulation and distribute the poisons throughout the
body before the proper organs could dispose of them.

598. One who is suffering from nervous exhaustion,
unable to do anything whatever, abhors the idea of
working or attending to business; but the presence of
this symptom is a protection. If the individual were not

328 ELEMENTS OF PHYSIOLOGY

forced to rest, he might continue at his business and com-
plete the exhaustion.

599. Symptoms and the Disease. — A distinction should
be made between the symptoms and the disease. The
symptoms are to warn the patient to allow the curative
process to go on, and they should not be combated. If a
log fell on a man and he yelled aloud, would it suffice to
stuff a handkerchief into his mouth ? No, the important
thing would be to remove the log. If you have a head-
ache, the quickest way to relief is to take antikamnia, or
some of the other poisonous coal-tar compounds, or per-
haps morphine. But if you do not wish to cause further
injury to the body, drink plenty of water to cleanse the
stomach, if the trouble is there, or go out and breathe fresh
air and rest the mind, if the trouble is mental. If you had
a corn on the toe, would you burn it off with salicylic acid
only to have it come back, or would you wear comfortable
shoes so that the corn would go away of itself ? If
the cause were not promptly removed, the corn might
become so deeply rooted that it would be very slow to
leave.

600. Remove the Cause of the disease, and the symptoms
usually disappear of themselves. It is said that there
are one thousand seven hundred diseases. There are
hardly more than half a dozen ways of getting sick;
errors in diet and dress, poor ventilation, overwork, under-
work, exposure, worry, are the underlying causes of all
diseases. The ways of getting well are likewise few.
Correct the habits of eating and drinking, avoid poi-
sons, work enough but not too much, breathe clean air,
keep the body clean and free enough for perfect ease
of movement, and keep the mind contented, — these arc
the first laws of healing. (Read notes 5 and 6, page 332.)

601. What common drug causes insalivation (uncontrol-
lable flow of saliva for a time) with loss of most of the

SOME SPECIAL REGULATIVE PROCESSES 329

teeth, and weakness for life ? Do these evil effects occur
more often when the drug is prescribed by a physician, than
by one of the self-appointed home doctors that recklessly
tinker with the health of family and friends ? What com-
mon drug causes defective hearing and deafness? Whether
the trouble is located in the heart or the stomach, or the
feet or the head, what organ must always bear the burden
of taking the medicine into the system ? How is dyspepsia
caused by drugs ? Which system first becomes diseased
from frequent use of stimulant or narcotic drugs? Is it
easier to prevent sickness by hygiene than to cure it?
Did you ever know of any one who took better care of his
horse than he did of himself ? If Dr. Tanner had worked
hard during his fast, what would have been the result ?

NOTES

i. Treatment for a Cold. — Rest ; sleep; a light diet of toasted
bread, and fruits. This may be followed by a hot mustard foot-bath,
the patient drinking, meanwhile, several glasses of hot water to start a
free perspiration and open the pores of the body. Thus impurities are
gotten rid of and the circulation of the blood is restored. After the feet
have been soaked in hot water for ten or fifteen minutes, immerse them
for a second in cold water and dry with a rough towel The patient
should go immediately to bed. It is well to provide a rubber bag of
hot water or a hot brick for the feet.

2. Approach of a Cold. — On the threatened approach of a cold, the
nose should be kept clear at all hazards, by frequently blowing it in such
a way as to cause as little irritation as possible, and by keeping the mouth'
tightly closed, drawing every breath through the nose. This treatment
often averts the cold, provided chilling or overheating of the body is
avoided for a time, the body being naturally more susceptible to draughts
or to any kind of exposure, than it is at other times. The coming of
a cold is often made known by a slight hoarseness. There may yet be
time promptly to moderate the diet, or cease the exposure, or change
the bad habit, which is bringing on the cold. Omitting a meal may do
good now when it would accomplish little if tried later. Why are colds
caused more quickly by draughts on a part of the person than by draughts
that blow on the whole body ? Question for discussion : Should the vital

330 ELEMENTS OF PHYSIOLOGY

organs or the limbs be the more warmly clothed if there is any difference
between the protection given them ? Suggestions : Distance from heart,
delicacy, natural activity of circulation, effect of exercise. (Read note 7,
page 332.)

3. Chronic Rheumatism. — Wherever it is located, the general
treatment should be about the same. You must improve the general
health. You must use the muscles of the entire body, moderately,
daily, particularly those in or near the part affected. If you can move a
finger, a wrist, an elbow, or any joint affected, in the least without pain,
do so, and continue to do so several times daily. You can in due time
make the affected parts move more and more freely. You must practi-
cally live out of doors, breathing fresh air freely and constantly. Your
food must be plain, very moderate in quantity, and thoroughly chewed.
These are important.

Too much food, and improper kinds, particularly meats, and lack of
exercise, beyond question, are the chief causes of the condition of the
body that allows rheumatism to gain a foothold. Exposure to damp-
ness, sitting on the ground, getting chilled when heated from exercise,
— these may be the immediate inciting causes, and they should always
be avoided, but there is an unhealthful condition of the body back of
them. To cure, remove this unnatural condition. Unless the trouble
has gone too far, and the joints have become solid, nature will remedy
the trouble if she has a fair chance. Bathing and brushing and rubbing
the skin are important, as they help more impurities to work out through
that channel. And do not forget to drink freely, all you have the
slightest desire for, of pure, soft water. In most cases it requires years
of improper living to cause the condition that makes rheumatism
possible. It takes months and perhaps years of care and persistent
effort to get entirely rid of it. Most of those who have suffered with
chronic rheumatism have no faith in the power of medicine to effect
a permanent cure. Nature must do it, and you must help by giving her
every chance.

The great trouble in effecting a cure of this .disease is the long and
persistent effort necessary. Many will not stick to it long enough. But
perseverance with the treatment described will bring the desired result
and it is the only way in which a lasting cure can be made. Medicines
may relieve at times, but there is something wrong in the way of living
that causes rheumatism, and until that is changed there can be no
permanent cure.

4. Water-drinking. — " The body of man is about four fifths water.
The teeth, the hardest and densest tissue in the body, contain ten per
cent of water ; the bones are thirteen per cent water, the muscles are

SOME SPECIAL REGULATIVE PROCESSES 331

three quarters water, and the blood four fifths. Gastric juice is ninety-
seven per cent, sweat is ninety-eight per cent, and saliva is ninety-nine
per cent water.

All the vital processes are carried on more or less through the agency
of water. Without food a man can exist for sixty days, as has been
demonstrated by experience. But six or eight days without water in
some form means a horrible death. As one authority expresses it:
"Water is a very important food element, as all physiologic changes
take place in a watery solution. Water is the medium through which
the body is nourished."

It must always be remembered that the water excreted from the body
is heavily laden with various poisonous matters. For instance, the sweat
contains about one half of one per cent of urea, besides certain lactates,
sudorates, and inorganic salts. The kidney secretion contains nearly,
two per cent of urea, also uric acid, creatin, creatinin, xanthin, leucin,
cystin, taurin, besides many other poisons.

Few people drink enough water. Nine out of ten people who suffer
from chronic constipation, " biliousness," habitual headache, kidney dis-
orders, etc., are, in reality, merely in need of more fluid, with which the
impurities formed in their bodies may be washed away. One week of
free water-drinking will "cure " many of these cases.

Water is the best "cathartic" — the only safe cathartic — known.
The cathartics usually given act by causing an irritation in the intes-
tinal tube, as a result of which a large amount of water is drawn from
the rest of the body to the intestine. But the general system suffers
for the fluid thus drained off, and the after effect is to leave the intestine
in a worse condition than in the beginning. Only by another dose can
the fluid be drawn back into the intestine, and then the reaction and
resulting constipation are more marked than before. So with repeti-
tions the matter becomes worse and worse. As all practical physicians
know, the most intractable cases of constipation are those resulting from
the habit of taking cathartic drugs.

In disorders of the kidneys, water-drinking is quite the most impor-
tant feature of the treatment. The kidneys are mainly filters, their
function being mainly to separate and rid the body of a certain por-
tion of water laden with impurities. The more pure water taken into
the system, up to a certain point, the less work there is for the kidneys.
There need be no fear of overtaxing the kidneys by free drinking of
pure water. When, however, one drinks large quantities of any other
fluid, such as wine or beer, the work of the kidneys is enormously
increased. In fact, it is safe to say that kidney disease always follows
the excessive use of beer.

332 ELEMENTS OF PHYSIOLOGY

For one unaccustomed to free water-drinking it is not always easy to
contract the habit. Some application is necessary. The following is
a good rule for general usage : On rising, two tumblers of cold water.
Then allow half an hour's interval before breakfast. Two hours after
breakfast, and until within a half hour of lunch or dinner, three tumblers
of water. During the interval between two hours after the midday meal
and one half hour before supper or dinner, three or four tumblers.
During the time between two hours after dinner or supper until bed-
time, two tumblers. This means ten tumblers, or about two quarts per
day; and this is as little as any one can afford to take."

— Adapted from W. R. C. LATSON, M.D.

5. Nature alone can cure. — This is the highest law of practical
medicine. . . . Nature creates and maintains ; she must therefore be
able to cure. — ROKITANSKY.

6. Appetites given away. — A lady once asked a physician where
she could get an appetite. " Out in the fresh air," he said ; "just go
right out and get one. Nature has thousands of appetites to give away.
The winter atmosphere is full of them. All that Nature asks is that
you come after them yourself."

7. That modern clothing is ugly and inartistic, that it is destructive of
ease, grace, and expressiveness, that it produces stiffness, rigidity, and
awkwardness, there can be no doubt.

One of the most learned and famous physicians in Europe has stated
that the principal cause of modern disease is clothing. A cramped
body means disease. The body must be free from pressure. Continu-
ous pressure anywhere means derangement of function. The worst
feature of clothing is that it occasions pressure at certain critical points,
namely, around the chest, about the waist, at the back of the neck, and
about the limbs. The tightly-buttoned coat and the snug-fitting dress
make natural breathing impossible. The ribs are drawn inward and
downward, the breastbone is depressed, and the beautiful rotundity of
the arched chest is lost — usually forever. The pressure upon the back
of the neck from a shortened coat-collar causes the head to fall forward
and affects the chest in the same manner.

The most injurious effect of the corset is that it depresses and con-
tracts the chest, and thus not only impedes the action of the heart,
lungs, and stomach, but causes a prolapse, or falling, of all the organs.
Another injurious result of the corset-wearing is that it interferes with
the action of the intestines (peristalsis) and with the blood circulation,
thus producing constipation and various inflammatory conditions and
displacements of abdominal and pelvic organs.

The pressure of a tight hatband is undoubtedly the principal cause

SOME SPECIAL REGULATIVE PROCESSES 333

of baldness among men. Women, who wear hats that sit lightly upon
the head, are seldom bald. In men the pressure of the tight hatband
cuts off the blood supplying the roots of the hair with nutriment, and
thus causes the death of the hair. I have known obstinate chronic
headache to disappear promptly upon the removal of a tight neck
dressing. These high, tight neck dressings which have been so much
the fashion recently have, in many cases, completely ruined the exquisite
contour of the neck.

Another evil effect of modern clothing is that by its thickness, it
interferes with the excreting and respiratory action of the skin. The
work of excretion is thus either thrown upon other organs already over-
taxed, or upon some tissue which the body selects as a possible medium
for elimination. Thus it is likely that catarrh is always caused by the
inactivity of the skin. The matter thus left in the body seeks egress
by means of the mucous membrane, which is merely a kind of internal
skin, and so we have catarrh. — Condensed from Health Culture.

CHAPTER XVIII
THE SPECIAL SENSES

602. In the special senses — sight, hearing, smell, taste,
touch (including the temperature sense) — we refer the
sensations to some external cause, but general sensations
(fatigue, pain, hunger), as previously stated, are referred
to our own bodies. You learned that the muscular sense
is made up of special sensations of touch and general
sensations from the muscles. Hence the much discussed
question as to whether the muscular sense is a sixth special
sense, is best answered by classing it with the general
sense. The special sense of touch has been studied in a
previous chapter.

603. The Sense of Taste (Fig. 165). — It was mentioned
that the tip of the tongue has a very keen sense of touch.
The tongue is a very muscular organ, and when we are eat-
ing, it helps to keep the food between the teeth ; it also does
the chief part of the work in the beginning of the process
of swallowing. But perhaps its most important function is
to afford a home for the nerves of taste. These nerves
consist of a branch of the fifth pair of nerves, which are
distributed over the front part of the tongue, and the ninth
pair, which go to the back part of the tongue (Fig. 201).
Although we often speak of food as being palatable, the
sense of taste in the palate is very feebly developed.

604. What we call flavors affect us through the sense
of smell. If the nose be closed with the hand, a piece of
onion placed on the tongue does not have the " taste " of
onion at first, nor at all, unless particles are wafted up and

334

THE SPECIAL SENSES 335

pass through the pharynx into the nose. An apple is, un-
der the same conditions, as tasteless as an Irish potato. If
the nose is held shut, ground coffee placed upon the
tongue loses its flavor and is as tasteless as sand, if the
tongue is wiped dry. The way to make these tests is
to obtain the articles and have them given to you for tast-
ing without knowing which you are getting; then find
whether or not you can tell the difference.

Substances, in order to be tasted, must first be dissolved
on the tongue. The tip of the tongue is most sensitive
to sweets and salines, the back part to bitters, and the sides
to acids.

605. The Sense of Smell (Fig. 208). — In quiet breathing
most of the air passes along the lower parts of the nasal
passages, just above the hard palate. Fibers of the olfac-
tory nerve end mostly in the higher part of the nasal
passages. When we wish to test an odor, we sniff, that
is, we take a sudden inspiration by jerking the diaphragm
down ; a volume of air larger than usual rushing in, more
of it passes over the parts of the walls in which the
olfactory fibers are located. It is necessary that the sub-
stance producing the odor be in a very finely divided
condition, probably gaseous.

606. Smell has its source in the beginnings of the respir-
atory passages, just as taste, is at the gateway of the ali-
mentary canal ; and just as taste by its influence on the
salivary and gastric glands, greatly influences digestion, so
the sense of smell greatly influences the respiratory acts.
The breathing of a pleasant odor increases the depth of
the breathing. Pleasant odors, as of flowers and of fresh
country air and of the forest, contribute to our health and
well-being. Why do foods lose flavor when one has a
very bad cold in the nose ?

SUBJECT FOR DEBATE. Resolved, That Dr. Oliver
Wendell Holmes's assertion is false, viz : If all the drugs

ELEMENTS OF PHYSIOLOGY

in the world were dumped into the sea it would be a great
deal better for mankind — and a great deal worse for the
fishes.

607. THOUGHT LESSON. How the Body shows that God
is Good. —

1. Name six beneficent natural provisions for repair of
accidental or unusual injuries to the body.

2. State six facts in anatomy showing provisions for
protection.

3. State six similar facts in physiology.

4. Name four anatomical provisions for convenience in
use.

5. Name four devices used in machinery, examples of
which occur in the body.

6. Name three devices of architecture found in the
body.

7. Why have the ears, eyes, nose, and mouth been
assigned the positions relative to one another which they
occupy in the head ?

SIGHT

608. By the use of the senses thus far studied, we
learn almost nothing of the external world except by
actual contact. Sight and hearing tell us of objects at
a distance. Without the eye the body is comparatively
helpless.

609. The Orbit (Fig. 51). — The deep bony socket in
which the eye rests is called the orbit. Its walls are formed
by inward processes of the frontal, malar, and several other
bones. There is an opening in the deepest part of the
socket for the entrance of the optic and oculo-motor nerves,
and the blood vessels that supply the eye ; the deep portion
of the orbit is partly occupied by a cushion of fat upon
which the eyeball rests, and which yields to some extent
when the eye is struck.

THE SPECIAL SENSES

337

610. Oculo-motor Muscles (Fig. 213). — The eyeball is
capable of being turned in all directions by means of six
slender muscles which begin in the back part of the orbit.
Four of them are straight. The one above turns the eye
upward, the one below turns it downward, the one toward
the nose turns it inward, and the one toward the temple
turns it outward. The other two are oblique. The supe-
rior oblique muscle passes forward through a loop which
serves as a pulley

near the inner upper
front part of the orbit
(Fig. 213). It rotates
the eye in one direc-
tion, and its antagonist,
the inferior oblique
muscle, rotates it in
the opposite direction.
"Cross eyes" are
caused by too great
contraction of the in-
ternal straight mus-
cles, and "wall eyes"
are caused by too great
contraction of the ex-
ternal straight muscles. The defects may be remedied by
a skillful surgeon, who cuts the proper muscle with a
suitable instrument, and permits it in healing to become
attached to another point farther back.

611, A person is blind while the eyes are moving.
Watch while some one in front of the class tries to
move the eyes gradually and uniformly across the field
of vision. Do the eyes move by jumps or steadily? The
motions of the lids and eyeball give the expression of the
eye. The eyeball itself has hardly more expression than
a glass eye.

z

FIG. 213. — A, the Muscles of the Right Eyeball
(viewed from above). B, the Muscles of the
Left Eyeball (viewed from the outer side) .

S.R, superior rectus; Inf.R, inferior rectus; E.R,
external rectus; S.Ob, superior oblique; Inf. Ob,
inferior oblique; //, the optic nerves; ch, their
crossing or chiasma; ///, the third cranial nerve.

33*

ELEMENTS OP PHYSIOLOGY

612. The Conjunctiva. — The eye is apparently set in a
slit in the skin of the face, but this is not really the case.
The skin of the eyelids turns inward over their edges and
becomes a thin, transparent, and exceedingly sensitive
mucous membrane, called the conjunctiva. It is, like
other mucous membranes, composed of epithelial cells.
The conjunctiva goes back under the lid and over half
the eyeball itself to the other lid, so that the eye is really
behind the skin. When the eye is directed very much

to one side, the con-
junctiva is sometimes
seen lying in wrinkles.
The veins which we
think we see in the
white wall of the eye-
ball when the eye is
"blood-shot" are usu-
ally in the conjunc-
tiva, which is so trans-
parent that we do not
easily see it unless its
vessels are swollen.

613. The Eyeball

(Fig. 214) is a globular chamber filled with transparent
fluids. By studying Fig. 214 you will see that its wall
is made of three layers, or coats. The sclerotic coat in
the "white of the eye" is the tough white outer coat
of connective tissue. It preserves the shape of the
eye and serves for the attachment of the muscles. This
coat is pierced in only one place, and that is for the
entrance of the optic nerve. It is continuous over the
front of the eye, where it becomes transparent, and is
called the cornea. You can see the cornea bulging out
in the front of a classmate's eye if you look at the eye
from the side. The middle coat, the coat just within the

etinji
horoid
'erotic coat

FiG. 214. — The Anatomy of the Eye.

THE SPECIAL SENSES 339

sclerotic, is the choroid. It consists of pigment cells and
blood vessels; its function is to absorb the superfluous
light which may pass through the retina, or third and inner-
most coat. This light, if reflected to and fro within the
ball, would confuse the vision. The continuation of the
choroid's layer of pigment in front is the iris, which may
be of various colors, and which, besides the pigment, con-
tains muscular fibers. Unlike the sclerotic, the choroid is
not continuous in front, for the iris is provided with an
opening called the//////. The retina is inside the choroid
and lines the chamber. It is made by the distribution of
the hundred thousand or more fibers of the optic nerve.
Just behind the iris is the crystalline lens whose func-
tion is to bring the rays of light to a focus on the retina.
It is in a transparent capsule from the edges of which mus-
cular fibers radiate to the wall of the eyeball. The lens
divides the chamber into two cavities. The small front
cavity, between it and the cornea, is filled with the watery
fluid called aqueous humor. The main cavity is filled with
the jelly like vitreous humor. A ray of light in going from
the outer world to the retina, passes through four parts
of the eye. Name them. This does not count the pupil,
which is simply a hole.

614. Use of the Lens. — Take a lens that is rounded
outward (convex) on both sides, such as a hand magnifier,
or even a strong lens from an old per-
son's spectacles. Hold this up on the
side of a room opposite to a window
and catch the image of the window on FIG. 215 -Refraction of
a white card-board held back of the Lisht-

lens. This illustrates how the image
of an external object is formed by the

. „. , , ,f of light rays.

crystalline lens upon the retina. If

some one stands up in the window, does he appear in the

upper or lower part of the image ? If he moves to the

340

ELEMENTS OF PHYSIOLOGY

right, in what direction does his image move ? The
reversals are explained by the crossing of the rays of
light as they pass through the lens. If two lenses of
different thickness be used, it will be found that the card-
board must be moved closer to catch the image from the
thicker lens.

615. Accommodation (Fig. 216). — Hold a pencil or finger
in line with some object, as a picture on the wall. When

IRIS

C.M.

FlG. 216. — Diagram to illustrate Accommodation.
Sc, sclerotic ; C.M . , ciliary muscle ; Sp. I, suspensory ligament ; C /, crystalline lens.

looking at the finger, the picture is blurred and vice versa.
When looking up from a book that we are reading, to a
distant object, we do not realize that any change in the eye
is necessary ; but the lens changes
in shape, becoming more flattened
for the more distant object, and
becoming thicker again when a
near object is looked at, thus
always bringing the rays to a focus

FIG. 217.

Normal Eye, in which Parallel Rays , .

of Light (A, A) focus the image upon the retina at whatever dis-
tance the object may be. But the

power fails at a point called the near point, about four
inches from the eye for most persons, and the image
becomes indistinct. The change in shape of the lens is

THE SPECIAL SENSES

341

called accommodation ; it is brought about by means of
the muscular fibers around the lens. Straining of the
muscles is required for looking at very near objects.

616. Defects of Vision. — In near-sighted eyes (Fig. 218)
the eye is too long from front to back, and the rays come
to a focus before reaching the retina. Among savage na-
tions, where no books are used, almost every one has good
sight, and nearsightedness is hardly known. Nearsighted-
ness may be inherited or may begin with children at school.
Some children seem to have a natural wish to get their
eyes close to the book or writing. This is the very worst

FIG. 218.

Myopic, or Nearsighted, Eye, in
which Parallel Rays of Light
(A", A"} focus the Image in Front
of the Retina at C' , producing a
Blurred Image on the Retina at
Bff, the Rays diverging from C1.

FIG. 219.

Hypermetropic, or Farsighted, Eye, in
which Parallel Rays of Light (A't
Af) are focused behind the Retina
at C, producing a Blurred Image
at B>.

thing for nearsightedness. The head should be held erect
in reading, to prevent the blood congesting in the eyes,
and to prevent round shoulders and flat chest. The proper
distance for reading is fourteen to eighteen inches. The far-
sightedness (Fig. 2 1 9) that occurs in youth is caused by the
eyeball being too flat. In the farsightedness of old age the
lens has also lost its elasticity, so that its shape cannot be
sufficiently changed to bring the lights from near objects
to a focus on the retina. In farsightedness, convex glasses
are used, and in nearsightedness, concave glasses are used.
Astigmatism is a defect caused by unequal curvature of the
cornea in different directions (Fig. 220).

617. Regulation by Iris of Amount of Light admitted.
— Look toward a bright window or the sky and note

342 ELEMENTS OF PHYSIOLOGY

by means of a hand mirror the size of the pupil. Turn at
right angles to the light, still looking in the mirror, and
note the size of the pupils. What have you noticed about

the eyes of a cat at night or in a
darkened room ? How do your
own eyes feel when going from
the dark into a lighted room ?
Can you see as well when you
first go from a brightly lighted
room into a dim lighted one, as af-
ter being in the dim light for a
short time ? The iris contains cir-
cular muscle fibers, which reduce

FIG. 220. -Test for Astigmatism. the size Qf the pupil> and mdi_

If this defect exists, the lines that run , • /-•• 1-1 i

in a certain direction will appear atmg fibers, which enlarge the

d7rSionsthan the Hnes in °ther PUP*1' The arrangement of pig-
ment sometimes follows the line
of the fibers. Have you ever noticed lines in the iris ?

618. After-images. — Did you ever whirl a stick with a
glowing coal on its end ? What was noticed ? Can you
notice anything similar if you shake the hand up and
down quickly before the face ? If you gaze for a moment
at a bright light, then quickly close the eyes, what is noticed
after the eyes are closed ? These effects are produced by
the bleaching action of light upon the pigment of the retina,
an effect which persists for a fraction of a second after the
light is removed.

619. The Yellow Spot, or center for most distinct vision
(especially for color), is near the middle of the back part
of the retina (Fig. 214).

620. Blind Spot. — Light falling on the optic nerve itself
does not give the sensation of light, but gives it only when
falling upon the ends of the nerve fibers. Where the
optic nerve enters the eyeball, there are none of these end-
ings, and the light that falls there does not enable us to

THE SPECIAL SENSES 343

see anything. In the following experiment shut the right
eye, and be careful not to let the eye waver: —

* Read this line slowly. Can you see the star all the time ?

If not, change the distance to the book and read the line
again. In the human eye the optic nerve enters not in the
center, but at a point toward the other eye. Although the
optic nerve along its course is not sensible to light, yet if it
be cut, it does not give pain, but gives the sensation of a
flash of light.

621, THOUGHT LESSON. The Eye. — (In writing out
this lesson, underline the words you supply.)

1. The eye is shielded from blows by bony projections of
, , and .

2. The hairs of the eyebrows lie inclined toward in

order to turn from the .

3. The eyelashes are to keep out and . I find

by trying it that I [can or cannot] see the position of a
window with my eyes closed.

4. The tears are to . We wink in order to carry

the over the , also in order to and to .

5. The front of the eyeball looked at from the side is

seen to be . It is called the cornea. The colored

portion of the eye, the iris, is to the amount of .

6. The hole in the iris, occupied by the transparent

aqueous humor is called the . It is for the purpose

of .

7. It appears to be black because no is from

the interior wall of the eye. I know that the iris is
partly muscle, because it the size of the .

8. By holding my finger in line with writing on the black-
board, I find that I [can or cannot] see both finger and
writing distinctly at one time. This is because in order to

focus the upon the , the must change shape

for every change in the distance of the object looked at.

344 ELEMENTS OF PHYSIOLOGY

622. Care of the Eyes. — Sight is Priceless. (When
reading is mentioned in these suggestions, it is meant
to include such work as writing, sewing, embroidering,
etc.)

1. The light should be steady, not flickering ; we should
not read after sunset by the fading twilight ; we should not
read with the sunlight falling on the book; we should
not read facing a window or with a light directly in front,
unless the eyes are protected by a shade. The lamp should
also be shaded. Incandescent electric lights give an uneven
light, because of the shadow cast by the filament; a shade
diffuses its light more evenly and protects from the glare.
Light curtains diffuse the light evenly, but dark curtains
cause lights and shadows.

2. The state of the eyes is of importance : We should
not read when tired or sleepy; when convalescing from
an illness; with the head bent down; or heated by the
burner ; when the eyes are sore ; when they are tired,
unless we rest them every few minutes by looking at
far objects ; when riding in jolting cars and carriages ;
when the circulation is impeded by tight clothing around
the neck.

" Tobacco blindness " sometimes results from smoking.
The first symptom is color blindness, which is followed by
haziness of vision, and finally, by partial or complete loss
of sight.

3. The kind of work is of importance : The type
from which books are printed should be large. The
paper should not be pure white or glazed, but a neu-
tral tint; it should be opaque, so that the printing will
not show through from the reverse page : the lines
should not be more than four and a half inches long.
Publishers of magazines are the worst offenders in using
shiny glazed paper because it brings out the beauty of
fine engravings.

THE SPECIAL SENSES

345

FIG. 221.

A Front View of the Left Eye, with
the Eyelids partially dissected
to show Lachrymal Gland, L. G.,
and Lachrymal Duct, L.D.t to
Nose.

623. The Tear Gland is located above the eyeball, be-
tween the ball and the bony arch on the side toward the
temple. It is flattened and oval in shape, about three quar-
ters of an inch in length. About ten small ducts lead from
it and open on the under side of the
upper lid. The secretion that it fur-
nishes to the conjunctiva is formed
continually. The tears pass across
the eye and flow into two small ducts,
the openings into which can be seen
on the borders of each eyelid near
the inner angle of the eye. They
lead to a canal which empties into
the nasal passage (Fig. 166). When
one weeps, why is it necessary to
blow the nose frequently ? At the ordinary rate of sup-
ply, the tears do not overflow, as there is a waxy secretion
along the edge of the eyelid that turns them toward the
ducts. When have you noticed a waxy
secretion in the corner of the eye ?

624. The Need of Two Eyes. — We
judge the distance of objects by the
lines of convergence of the two eyes.
A boy with one eye has difficulty in
knowing when a ball thrown will
reach his hand. When we look at
FIG. 222.-Diagram of a a solid object, each eye sees a little
stereoscope. more of the object on its side than

Two photographs, A and 5, are doCS the Other. Thus tWO CVCS make
seen combined at C. The rays *

of light from A and B are re- it easier to distinguish solid bodies.

fracted by the prisms into the ._ . .

eyes so that they appear to By taking tWO photographs Of 3. SCQUQ

from slightly different points and

arranging them so that the eyes look at the pictures
separately at the same time, the idea of solidity is given.
The stereoscope (Fig. 222) secures this arrangement.

346

ELEMENTS OF PHYSIOLOGY

625. Cooperation of Eye and Touch. — The infant reaches
for the moon. It is learning by reaching for things seen to
judge of distance. By feeling of
things seen it soon learns to tell
round things from flat things by
sight alone. The aid that touch gives
to the sense of sight is illustrated by
the case of a boy who had been blind
from birth and received sight at the
age of twelve years by means of a sur-
gical operation. At first he could not
distinguish a globe from a circular
card until he had touched them.
He had become acquainted with dogs
and cats by feeling but did not know

FIG. 223. — Diagram
Course of the Retinal Nerve
Fibers.

of the them apart by sight alone. One day

Light from A strikes the outer part

he picked up the cat and .recognized
for the first time the connection be-
tween the new sense of sight and the
these parts go to the right half oi^ familiar one of touch. On put-

of the brain, B. A/ represents

the nose. The spots A and A ting the cat down he said, " So, puss,
I shall know you next time."

HEARING

on the retinae are habitually
stimulated together.

626. The ear may be described in three parts, the outer,
middle, and inner ear (Fig. 224). The outer ear consists
of the cartilaginous concha, the part that is usually spoken
of as the " ear," and the meatus, the canal leading into the
head from the lower part of the concha. Which part of
the concha is not cartilaginous but fatty tissue ? Part of
the wall of the meatus is of cartilage, but the deeper part
has a wall of bone. The entrance to the meatus is guarded
by hairs, and its wall is covered with a bitter wax secreted
by glands in the lining. Its inner end is closed by the
tympanic membrane, which is sometimes called the driim,

THE SPECIAL SENSES

347

but it is only a drum skin. Three little bones stretch across
the true drum, which is the middle ear, to a small film
separating the middle ear from the internal ear. These
three little bones are called the hammer, anvil > and stir-
rup. The middle ear communicates
with the pharynx by a narrow tube
called the Eustachian tiibe. This
tube is for the purpose of admit-
ting air to the middle ear, so as to
equalize the air pressure on each
side of the membrane and prevent
straining it. Sometimes blowing
the nose may press the air up into
the middle ear and press the walls FIG. 224. — Diagram of Left Ear.
of the Eustachian tube together and close it. This causes
slight deafness for the time. The pressure may be relieved
by holding the nose closed and swal-
lowing, thus opening the passage to
the middle ear. One end of the
hammer is attached to the inner sur-
face of the drum skin ; the other end
is attached to the anvil ; and one
prong of the anvil is attached to the
stirrup, which in. turn is fastened by
base to the small film stretched
across a round hole in the bone, open-
ing into the inner ear, or labyrinth.
The inner ear consists of several
cavities containing a liquid in which
rest the endings of the auditory nerve. The cavities are
the snail-shell and the three loops, or semicircular canals.
627. Sound waves, entering by the meatus, set the drum
skin to shaking ; the vibrations are conveyed by the
chain of bones across the middle ear to the liquid of the
inner ear. The wave travels through air in the outer ear,

FIG. 225. — Bones of Right
Ear, enlarged.

c, hammer; d, anvil; e,ft
stirrup.

348 ELEMENTS OF PHYSIOLOGY

solids in the middle ear, and liquids in the inner ear. The
vibrations of the liquid start nerve impulses in the fibers
of the auditory nerve, and when these impulses are re-
ceived and interpreted in the brain,
the miracle of the conversion of
the external sound wave into the
sensation of sound is complete.

628. The Equilibrium Sense. —
It is now believed that the semi-
circular canals of the inner ear
FIG. 226. — The inner Ear, or are not concerned in hearing. The
Labyrinth. weight of the liquid they contain

gt vestibule; /", snail shell; k, semi- • .-i ^-i

circular canals. pressing Upon the HQVVQ fibers

located in them and exerting a

varying pressure according to the position of the body,
gives us the "equilibrium sense," which enables us to know
the position of the body at all times, that we may preserve
its equilibrium. Sight and the muscular sense also prob-
ably contribute to maintain the equilibrium.

629. Care of the Ear. — The meatus is self-cleansing ;
the wax changes into dry scales, which fall out. The
external ear should be washed, but when we reach the
passage, we should go no deeper than we can easily reach
with the tip of the finger covered with a damp cloth ; espe-
cially the finger should not be forced into the tender ears
of children. A blow with the flat hand upon the ear may
force the air in and injure the tympanum. Picking the ear
with hard or sharp objects is dangerous to the tympanum.

630. Sometimes the wax collects in a lump near the
drum, causing deafness. The remedy is to syringe the
meatus with warm water until the lump is softened and
comes away. The bitter wax is a protection against
insects. Quinine often does great damage to the hearing.
Chronic cold in the throat reaching the ear through the
Eustachian tube sometimes injures the hearing.

THE SPECIAL SENSES

349

THE VOICE

631. The larynx, in which the voice originates, is a
cartilaginous box with three sides, the sharpest corner
forming a ridge in front (Fig. 227).
In many persons the larynx is promi-
nent in the neck, and is called the
Adams apple. The lid of the voice-
box, or larynx, is also of cartilage, and
is called the epiglottis. Across the
middle of the box are stretched two
bands, or half-curtains, called the vocal
cords (Fig. 228). Their ends are at-
tached to the front and back of the
larynx. They are not true cords, how-
ever, as they are thin and flat, and one

edge of each
band is at-
tached to the
side of the
larynx. Since

the cords run across the middle
of the chamber from front to
back, the free edges are brought
near together. The slit, or open-
ing between these edges, is called
the glottis. During ordinary
respiration the cords are relaxed

Larynx above the Vocal Cords, and the slit is wide Open. To
with the Mucous Membrane re- i j_i *.\. i j

moved make the voice the vocal cords

showing right vocal cord; left vocal must be brought very near to-

cord: cartilages to which the vocal , •, -, -, , • •, , j

cords are attached behind; front gether and drawn tight, and a
edge of the larynx. current of air must be forced

through the narrow slit and throw the cords into vibration.

The front ends of the cords are attached to the larynx just

4

FIG. 227.

View of the lett side of the
larynx; i, front portion
of hyoid bone; 2, upper
edge of larynx; 3, lower
portion of larynx ; 4,
second ring of trachea.

FIG. 228. — Cross-section of the

350

ELEMENTS OF PHYSIOLOGY

within the angle, or ridge, called the Adam's apple. The
rear ends are attached to two little movable cartilages at
the back of the chamber. The moving of these little car-
tilages by the muscles of the larynx brings the edges
together and tightens the cords.

632. Sound Waves, or sound vibrations, are imparted to
the air by the tremulous motion of the cords. The limits
of the vibrations which the human voice is capable of mak-
ing are from 42 vibrations per second for the lowest tone,
to over 2000 vibrations per second for the highest tone.

FlG. 229. — The Shape of the Mouth in sounding the Vowels a, e, oo.

Lower C of the soprano is produced by 256 vibrations per
second. The limits of vibrations which the human ear is
capable of hearing are from 16 to 50,000 vibrations per
second, but until they reach a rate of about 50, the sound
is more like a buzz than a tone. Some people cannot
hear the voice of mice, or the squeak of a bat, because of
the high pitch being beyond the limit of their hearing.

633. THOUGHT LESSON. How the Voice may vary. -
The rate of vibration of a cord, and hence the pitch of a
sound, are influenced in several ways. Is the string of
a violin or of a guitar tuned up or down by tightening it ?
Which is higher in pitch, a long or a short string of a harp
or a piano ? Which makes a higher note, the light or the
heavy string of a violin or a guitar? The pitch of the

THE SPECIAL SENSES 351

note given by a string may be raised in three ways : tight-
ening, shortening, or decreasing the weight of the string.
From these facts explain why the voice rises in pitch when
we are excited, the muscles at that time being contracted
with greater force. Why does a cold with congestion of
the cords cause a person to speak in a hoarse, deep voice ?
Why does a man, whose larynx is larger than a woman's,

FIG. 230. FIG. 231. FIG. 232.

A, Resonance Cavity of the Nose; B, Resonance Cavity of the Mouth; C, Resonance Cavity
of the Pharynx; D, Soft Palate; E, Tongue; F, Point at which Vibration begins.

Fig. 230 shows soft palate (Z>) in normal position, allowing air in naso pharynx to vibrate
in unison with initial note. Fig. 231 shows soft palate raised, shutting off this resonance
and rendering tone thin and hard. Fig. 232 shows another common fault. The tongue is
lowered, increasing the size of the mouth cavity. This increases the volume of the tone but
renders the quality harsh and hollow. (Latson.)

have the deeper voice ? Why does a boy's voice change as
his larynx enlarges ?

A man's voice has usually a pitch of one octave below
that of a woman or a boy. The range of the human voice
is about two octaves. The voice may also vary in —

634. Volume, or loudness, as well as in pitch. How do
we speak loudly at one time and softly at another ? If a tin
pan is struck gently, the sound is weak ; if it is struck with
force, the sound is louder. We make the voice louder by
stronger expiration of the breath, thus sending the air
with more strength against the tightened vocal cords.

352 ELEMENTS OF PHYSIOLOGY

Two persons sing a song together in the same pitch and
with the same loudness; yet you can readily distinguish
a difference in the two voices. This is because of a dif-
ference in —

Quality, which is the third variation possible in a voice.
Sound in wind instruments is strengthened by resonance,
which is a kind of instantaneous echo in the pipes.

635. The vibration of the vocal cords alone produces a
weak, squeaky sound, but their vibrations are reenforced or
strengthened by the vibration of the walls of the lungs and
windpipe below, and of the nose and mouth above. These
echoes, combining with and reenforcing the vibration of
the cords, determine the quality of the voice. Just as the
shape and material of the walls of the violin give the quality
to its tone, so the shape and condition of the nasal passages,
throat, etc., give characteristic quality to each human voice.
If the nasal passages are stopped up by catarrh, the per-
son is said to speak in a nasal tone, or through the nose,
but a "nasal" tone really results only when the sound
cannot come through the nose. Such a person's voice
does not change its quality, when he speaks with his nose
stopped with his fingers. But a voice which has correct
nasal resonance will change its quality when the nose is held.
Try it, and see whether your voice retains its nasal reso-
nance. Let one pupil read aloud at the back of the room
where the others do not see him, and find whether they
can tell, by the change in his voice, at which word he
closes his nose in the midst of the reading. The vocal
cords are not used at all in whispering. It is akin to
whistling.

636. Duration of Sound. — In singing, single sounds are
more or less prolonged. In speech, the principal changes
are in the duration of the sound, and in the resonance in
the mouth. In whispering, audible breathing is cut off by
the tongue and lips, and words are articulated, although

THE SPECIAL SENSES 353

no sound comes from the vocal cords. A public speaker
ordinarily utters 125 words per minute. If there are four
sounds to a word, this amounts to 500 sounds each minute
or eight each second.

637. Is the Voice a Stringed or a Wind Instrument ? -
The inappropriate names of the vocal cords may lead a
student incorrectly to suppose that the voice is a stringed
instrument. It is a wind instrument ; the vocal bands cor-
respond to the vibrating edge in the opening in an organ
pipe, the throat and air passages correspond to the pipe,
and the lungs correspond to the bellows that furnish the
current of air.

638. Alcohol and Tobacco. — Smokers are frequent suf-
ferers from affections of the throat. Smoking may produce
a constant " hacking" cough. The hot, poisonous smoke,
to say nothing of the poisonous vapor of nicotine, brought
in contact with the vocal cords, is almost certain to pro-
duce mischief. Singers and public speakers usually have
to give up the use of tobacco on this account. Cigarette
smoking is especially bad for the voice, as the smoke is in-
haled. The deep-toned voice of the chronic drinker may be
an indication of inflammation of the larynx, a disease from
which beer drinkers often suffer.

639. Care of the Voice. — The voice should not be used
more than is absolutely necessary when it is hoarse.
Catarrh may injure the voice by injury to the vocal cords
or by obstruction of the nasal passages.

640. The best way for a child to acquire distinct and
refined speech, is to hear it habitually. The number of
people that are allowed to grow up handicapped by hasty,
harsh, indistinct, or disagreeable speech, is very great.
Parents and teachers should remember as children are
growing up, what an advantage to them in after life a
refined, melodious voice will be. Nearly all children have
sweet voices when young, but many lose them before adult

2 A

354 ELEMENTS OF PHYSIOLOGY

life on account of acquired nervous habits, dusty and ill-
ventilated rooms, deformity of lungs due to restrictive
clothing, or from singing during the time their voices
are changing or attempting tunes beyond the compass of
their voices.

641. Culture of Voice. — Voice culture is often more of
a straining than a training. Its mechanical nature is re-
vealed by the term " voice building " (whatever that may
mean) used by some singing teachers. The pupil is taught
to raise the soft palate and depress the larynx, etc. (see
Figs. 230, 232). Rigidity of the muscles of chest, neck, jaw,
and larynx results and self-consciousness assumes charge.

When the singer does not listen" too closely to his own
voice, the muscles are more likely to be free from rigidity.
Muscles in this condition are perfectly dominated by the
mental state ; this applies to both tone and gesture. Breath-
ing exercises which call for a rigid, over-filled chest destroy
this flexibility.

CONCLUSION

642. Thus we see with reference to the care of the voice,
as with taking care of the health in general, that overcare
and too much effort have an effect opposite to that in-
tended. We must trust largely to the natural tendencies of
our wonderful organisms toward sound health and perfec-
tion of function. If we exert great effort and attempt very
much interference, we are likely, in our ignorance, to do
more harm than good. We do not even know what life is.
When we say that life consists of activity of the cells, we
are simply stating the limitations of science. The power
which causes this birth, growth, and destruction of cells
is beyond our comprehension. We know nothing of the
mechanism occurring in the protoplasm of the cells. All
that the wisest can say is : —

" In Nature's infinite book of secrecy
A little can I read.1'

APPENDIX

EMERGENCIES

Cuts. — There is danger of bleeding to death if an artery of any size
is cut. Stop the flow of blood immediately by compressing the artery
with the finger, between the wound and the heart. Next twist a hand-

FIG. 233

The method of applying the knotted
handkerchief, to compress a divided
artery. A, B, track of the inner
artery of the left arm.

FIG. 234.

A, C, the track of the left femoral
artery; the compress applied near
the groin.

kerchief and tie a hard knot in the middle. Place the knot over the
artery and carry the ends around the limb and tie it loosely. Place
a stick under the handkerchief and twist until the fingers can be
removed from the compression without return
of the bleeding (see Figs. 233 and 234).

Sprains. — See Chapter VI, § 124.

Broken Bones. — See Chapter VI, § 122. A
convenient bandage may be made out of a piece
of calico one yard square, by cutting it across
from one corner to another (Fig. 235). For
method of using bandage as a support for a
broken arm, see Fig. 236.

355

FIG. 235.

356

APPENDIX

To prevent Mouth-breathing, bands may be arranged as shown in
Fig. 237. Dr. Tafts, of Pittsburg, gets good results by sticking a strip
of court plaster across the closed lips.

Burns. — If the clothes catch fire, do not run, as this only fans the
flames, but wrap quickly around the body a coat, rug, shawl, blanket, or

other woolen article. The
skirts of girls are a source
of danger when they stand

FIG. 236.

FIG. 237.

near a fire in an open fireplace without a fender, or by a fire out of
doors. Life has sometimes been saved by throwing the victim to the
ground, and then putting sand or dirt on the burning clothes.

FIG. 238. — Resuscitation: Inspiration. (Brinckley.)

In Cases of Drowning the first thing to be done is to remove the
water from the throat and lungs by holding the person up by the
waist, with the face downward. Then draw the tongue forward and

EMERGENCIES 357

keep it in place by tying with the middle of a handkerchief or band, so
that it may not fall back and close the throat ; the ends of the band
should cross under the chin and be tied around the neck. Next pro-
ceed to restore by artificial breathing according to the method shown
in Figs. 238 and 239. The teacher should illustrate the method of
fastening the tongue, the pupil holding a short stick between the teeth
to represent the tongue. The teacher should then work the arms of

FIG. 239. — Resuscitation: Expiration. (Brinckley.)

the pupil to show inspiration and expiration in artificial breathing. The
boy need not lie down but should stand where the class may see him.

Artificial Breathing (Sylvester's Method), applicable to asphyxia
from fire, gas, electric shock, or drowning. A coat or cushion should
be placed under the shoulders to serve as a support. First Step (Fig.
238) : The arms should be raised above the head with force in order to
raise the ribs. Second Step (Fig. 239) : The arms should be lowered
and pressed against the sides so as to compress the chest. Repeat these
movements about fifteen times each minute, continuing for an hour or
several hours until natural breathing is restored.

Snake Bites. — Very few snakes are poisonous. The four snakes
of the United States that are virulently poisonous are the rattlesnake
(diamond rattler and common rattler), ground rattlesnake (has no
rattles V moccasin, and copperhead. The last-named is the most dan-
gerous. The copperhead is of a golden brown color, with dark V-shaped
blotches meeting on the back. All venomous snakes have broad tri-
angular heads and short tails. Their b'ite is known from the marks left
by the two fangs. Other snakes do not have fangs. The wound made
by a venomous snake should be immediately sucked. The blood should
be confined to the bitten member (see Figs. 233, 234). Potassium
permanganate and peroxide of hydrogen are valuable remedies. They
should be used only under direction of a physician.

358

APPENDIX

Poisons

Opium
Morphine
Codeine
Laudanum
Paregoric
Soothing sirup
Dover's powder

Carbolic Acid
Creosote

Arsenic
Rough on rats
Paris green
White arsenic

Phosphorus
Rat poison
Matches

Belladonna

Deadly nightshade
Atropin

Concentrated Acids
Sulphuric (vitriol)
Muriatic
Nitric
Oxalic

Alkalies
Lye

Caustic potash
Soda
Ammonia

POISONS AND ANTIDOTES

Symptoms Treatment and Antidotes

Drowsiness ; stupor ; con-
tracted pupils ; slow breath-
ing; perspiration profuse

Severe pain; odor of the
acid ; mucous membrane
white ; skin clammy

Cause vomiting 'or use stomach
tube; keep patient awake
by vigorous walking and
other means; dash cold
water on face and chest;
give strong coffee freely

Do not cause vomiting ; give
milk, or flour and water,
white of eggs

Intense pain in abdomen; Cause vomiting repeatedly;
thirst; vomiting; skin cold give hydrated oxide of iron
and clammy with magnesia (druggist),

then strong salt water

Vomiting; pain in stomach ;
purging

Enlarged pupils ; eyes bright;
mouth and throat dry

Feeling of burning in mouth,
throat, and stomach ; blis-
ters on lips ; vomiting and
weakness

Burning sensation; pain in
stomach; vomiting; diffi-
culty in swallowing; skin
cold ; pulse weak

Cause vomiting ; give strong
soap suds.magnesia in water

Cause free vomiting

Do not cause vomiting ; give
baking soda, 4 teaspoonfuls
to a glass of water ; chalk ;
soap ; lime ; magnesia

Do not cause vomiting ; give
olive oil ; thick cream ;
melted butter and vaseline ;
vinegar ; lemon juice

NOTE. — In those cases of poisoning where vomiting is necessary, it may be in-
duced by a drink of warm water, or powdered alum in a little molasses, or a
mixture of ground mustard in warm water. The vomiting should be repeated
until the stomach is thoroughly washed out.

INDEX

The meaning of each technical word is fully explained in the text when the word is first used.
This explanation can be found by using the first reference given. The numbers below
refer to pages.

Absorption, 207.

by stomach, 213, 221.
Acid, 54.

Air, composition of, 159.
Albino, 2.
Albumen, 28, 53.
Albumin, 28, 52, 192.
Alcohol, 255, 257, 14.
and gout, 43.
effect on —

energy of body, 323, 324.

heart, 113.

liver, 230.

lungs, 169, 170.

nerves, 292.

nervous system, 314, 315, 316.

nutrition, 42.

protoplasm, 42.

red corpuscles, 113.

skin, 14.

stomach, 204, 279.

temperature, 258.

voice, 353.

white corpuscles, 113.
Is it a food ? 204, 256, 257.
Alimentary canal, 205.
Alkali, 54.
Alkaloids, 188.
Ameba, 30, 281.

taking food, 31.
Anatomy, 25.
Antidotes, 358.
Antiseptics, 187.
Antitoxin, 183.
Appetite, 237, 262, 332.
Aseptic, 187.
Asphyxia, 357.
Astigmatism, 342.
Atlas, 62.
Auricle, 87.

Automatic action, 303.

Axis, 62.

Axis cylinder, or axon, 285.

Bacillus, 178.
Bacteria, 178.

destroyed in body, 182.
out of body, 186.

effects of, 181.

place in nature, 177, 179.

their work in the body, 179.
Balancing organ, 348.
Bandage, 355.
Baseball, 141.
Baths, ii.

kinds of, 22.

rules for, 23.
Biceps, 125, 128.
Bicuspid valve, 90.
Bicycling, 141.
Bile, 217.
Biology, 25.
Bleeding, 114, 355.
Blind spot of eye, 342.
Blister, u.
Blood, circulation of, 86.

control of flow, 97, 98.

function and composition, 82.

plasma, 83, 86.

rate of flow, 96.

red corpuscles, 58, 83, 84.

white corpuscles, 84, 182.
Blood vessels and heart, 88.

nervous control, 97.

structure of, 92.
Bone, alcohol and, 79.

cells, 40.

composition of, 71.

deformities of, 75, 76.

359

36o

INDEX

Bone {continued)

growth of, 41.

names of, 57.

nourishment of, 74, 78.

number of, 59.

of head, 58, 60.

red marrow, 58.

shapes of, 56, 68.

structure, 40, 70.
Boxing, 141.
Brain, 300.

coverings of, 300.

parts of, 301.

weight of, 301.
Breathing, see Respiration.
Broken bone, 74, 79, 355.
Bronchial tubes, 150.
Bronchus, 150.
Burns, 356.

Caecum, 222.
Canaliculi, 40.
Capillaries, 89.

structure of, 92.
Capsule of joint, 69.
Carbohydrates, 53, 193.
Carbon dioxid, 51, 160.
Carbon monoxid, 172.
Carpus, 65.
Cells, 26, 29, i, 2, 4.

ciliated, 151.

community of, 31.

division of, 31.

epithelial, 35.

life of, 30, 41, 116.

of bone, 40.

of cartilage, 38.

of connective tissue, 34.

of fat, 35.

of muscle, 121.

of nerves, 46.

parts of, 29.
Cellulose, 53, 249.
Cerebellum, 301.

functions of, 307.
Cerebro-spinal system, 296.
Cerebrum, 301.

functions of, 304, 307, 309.
Cervical, 61.
Chyme, 213.
Cilia, 151.
Circulation of blood, 82, 88.

hygiene of, 109.
Cleanliness, five degrees in, 174.

Clothing, 22, 191, 231, 262, 332.

and climate, 22.

materials of, 22.
Coagulation, 85.
Coccyx, 61.

Coffee-drinking, 14, 272.
Cold, taking a, 6, no, 329.
Colon, 222.

Complexion, 19, 20, 24.
Compositions or essays, subjects for, 162,

280, 316.
Condyles, 59.

Consumption, 176, 180, 190, 191.
Cooking, 239, 240, 242, 244, 246, 247, 248,

254-

Cranial nerves, 303, 304.
Cuts, 355.

Dancing, 141.
Dandruff, 5.
Debates, 177, 262, 335.
Dendron, 284.
Dermis, i.

organs of, 5.
Dextrin, 220.

Diaphragm (di'-a-fram), 154.
Diastole (di-as'-to-le), 87.
Dieting, 203.
Digestion, analysis of, 220.

hygiene of, 236.

outline of, 198.
Dislocation, 70, 75.
Division of labor, 32.
Dorsal, 61.
Drowning, 356.

Drugs, 14, 43, 179, 188, 237, 250, 280, 328.
Duodenum, 216.

Ear, structure of, 346.

care of, 348.
Emergencies, 355.
Emulsion, 53, 218.
Endothelium, 92.
Enteroptosis, 231.
Epidermis, i.

growth of, 4.
Epiglottis, 208, 349.
Equilibrium sense, 348.
Esophagus, 209.
Essays, see Compositions.
Excretion, 13.
Exercise, benefits of, 137, 142, 144.

dangers of, 143.

INDEX

361

Exercise (continued)

effect on growth, 146.

forms of, 141, 144.

mind and, 145.
Expiration, 148, 156.
Eye, 338.

care of, 344.

defects of, 341.

structure of, 339.

Fatigue, 312, 323.

Fats, 53, 194.

Femur, 66.

Ferment, 206.

Fermentation, 178, 179, 255.

Fever, 326.

Fibers, 29.

Fibrin, 85.

Fibula, 61.

Flavors, 335.

Follicle, 7.

and work, 200.

composition of, 243.

function of, 45.

ratios, 201.

sources of, 197.
Food, and climate, 53, 323.
Food substances, 52.
Freckles, 2.
Fruits, 243, 244.
Function, i.

Ganglion, 286.
Gastric glands, 212.
Gastric juice, 212.
Germicide, 187.
Germs, see Bacteria.
Girdle, of pelvis, 66.

of shoulder, 65.
Gland, 12.
Glottis, 349.
Glycogen, 288.
Gout, 79, no, 327.

Hair, 7, n.
Haversian canal, 40.
Headache, 266, 313, 314.
Hearing, 346.
Hemorrhage, 114.
Hepatic artery, 227.
Hepatic vein, 227, 228.

Hygiene, defined, 26.

in disease, 325-333.

of circulation, 109-118.

of digestion, 236-267.

of muscles, 137-146.

of nervous system, 309-319.

of respiration, 162-192.

of sight, 344.

of skeleton, 74-81.

of skin, 11-24.

temperance, 268-281.
Hyoid bone, 60.
Hypnotism, 316.

Indigestion, 215, 327.
Infectious diseases, 182.
Innominate, 66.
Inorganic, 25.
Inspiration, 148, 155.
Intestinal juice, 217, 219.
Intestine, large, see Colon.
Intestine, small, 216.
Iron, 54.

Joint, 68.

kinds of, 70, 71.
of arm, 79.
parts of, 69.

Kidneys, 234.

Lachrymal bone, 60.
Lachrymal duct, 345.
Lacteal, 218.
Lacunae, 40.
Larynx, 149, 349.
Leather, 2, 35.
Lens, crystalline, 339.
Levers, 126, 144.
Ligament, 69.
Lime, 54.
Liver, 222, 223.

a digestive gland, 223.

a guardian, 224.

anatomy of, 226, 227.

a storeroom, 228.
Lobule of lungs, 150.
Lumbar, 61.
Lungs, aid to heart, 103.

alcohol and, 169.

anatomy of, 148, 150.

nature of, 147.

362

INDEX

Lymph, 105.

relation to blood, 105.

why it flows, 107.
Lymphatic glands, 108.
Lymphatics, 106.
Lymphatic spaces, 104.
Lymphatic system, 104.

necessity for, 105.

Malar bones, 60.
Malaria, 183.
Mammals, 241.
Massage, 103.
Matrix, 38.
Maxillary bone, 60.
Membrane, 30.
Metacarpus, 65.
Metatarsus, 67.
Microbes, see Bacteria.
Mineral foods, 52, 54, 194.
Molds, 177.
Mole, 10.
Mosquito, 184.
Mouth, 205.

Mucous membrane, 6, 12.
Muscles, 118.

attachment of, 124.

cells of, 119.

contraction of, 46, 120.

intercostal, 155.

kinds of, 119.

names and positions, 127, 139.

nervous control of, 132.

structure of, 120, 122, 124.

tissue of, 45.

tone of, 136.
Muscular sense, 291, 334.

Nails, 9.
Narcotic, 14.
Nerve, 285.

center, 286.

coordination, 283.

motor, 49, 287, 291.

sensory, 49, 287.

structure of, 48, 285.

tissue, 46.
Neuroglia, 286.
Neuron, 285.
Nucleolus, 29.
Nucleus, 29.
Nuts, 244.

Oil gland, 7.
Opium, 42, 188, 280.
Organ, i, 33.
Organic, 25.
Organism, 44.
Osmosis, 222.
Overstudy, 175.
Oxidation, 44, 51.

Pain, 290, 325.

Palate bones, 60.

Pancreas, 217.

Papilla, 3, 7, 10.

Paralysis, 308.

Patella, 67.

Pelvis, 66.

Pepsin, 213.

Periosteum, 39.

Peristalsis, 210.

Peritoneum, 211.

Perspiration, 6, n.

Phalanges, 65, 67.

Pharynx, 149, 207.

Phrenology, 316.

Physician, 43, 74, 115, 142, 188, 280, 357.

Physiology, 25.

Pigment, 2.

Plants, how different from animals, 28,

50.

Pleura, 152.
Poisons, 358.
Pore, 5.

Portal vein, 222, 226.
Process on bone, 62.
Proteid, 52, 54, 193, 200.

test for, 196.
Protoplasm, 27.

how known, 28.
Proud flesh, n.
Ptomaines, 181.
Pylorus, 214.

Rectum, 223.
Reflex action, 294, 308.
Renal artery, 234.
Respiration, 147.

artificial, 356.

ease in, 158.

hygiene of, 163.

modifications of, 159.

muscles of, 165.
Resuscitation, 356, 357.

INDEX

363

Retina, 63.
Rheumatism, 330.
Ribs, 63.
Running, 141, 164.

Sacrum, 61.
Saliva, 206.
Salivary glands, 206.
Salt, 54.
Scars, 55.
Secretion, 13.
Semilunar valve, 88.
Sensation, special, 288.

general, 288.
Serous membrane, 12.

cavity, 12.
Serum, 85.
Shoes, 75, 122.
Sight, 336.

Sigmoid flexure, 223.
Sitting, 75.
Skeleton, arrangement of, 59.

functions, 56.

hygiene of, 74.
Skin, i.

care of, 20.

functions of, 21.
Skull, 59.
Sleep, 112, 309.
Smell, 335.
Snake bites, 357.
Spinal bulb, 50, 98, 302.
Spinal column, 61, 73.
Spinal cord, 292.
Spleen, 109.
Sprain, 75.

Standing, positions in, 78.
Starch, 53, 193.

test for, 196.
Stomach, 210.
Substances of the body, 53.
Sugar, 53, 193.

forms of, 219.
Sweat glands, 5, 6.
Sweeping, 163.

Sympathetic system, 109, 296.
Synovial fluid, 69.
System, i.
Systole (sys'-to-le) , 87.

Tarsus, 67.
Taste, 334.

Teeth, care of, 19.

milk teeth, 17.

number and names, 15.

structure of, 17.
Temperature, of body, 22, 320.

of house, in.

perception of, 290.
Tendon, 125.
Thoracic duct, 106.
Thorax, 63.
Tibia, 67.
Tissues, i, 33.

bony, 39.

cartilaginous,

connective, 34.

epithelial, 36, 37, 92.

fatty, 35.

master, 33.

muscular, 45.

nervous, 46.

supporting, 33, 34.

tabulated, 41.

Tobacco, effect on skin, 14.
on growth, 79.
on heart, 114, 115.
on lungs, 170.
on throat, 209.
on voice, 353.

instinct against, 160.
Tonsils, 209.
Touch, 289.
Touch corpuscles, 287.
Toxin, 181.
Trachea, 149.
Turbinated bones, 60.
Typhoid fever, 182.

Urea, 21, 133, 229, 234, 247.
Ureter, 234.

Vaccination, 185.
Vagus nerve, 99.
Vasomotor nerves, 97, 98.
Vegetarian, 244, 251.
Veins, 88, 102.
Ventilation, of schools, 171.

of churches, 170.

methods of, 173.

mistakes in, 174.
Ventricle, 87.
Vermiform appendix, 222.
Vertebra, 61, 73.

364

INDEX

Villi, 216.

Voice, care of, 354.

pitch, 350.

quality, 352.

tobacco and, 353.

volume, 351.
Vomer bone, 60.

Waist measure, 232.
Wart, to.

Waste products, 133, 198, 225, 229.

how measured, 199.
Water, 22, 52, 238, 330.
Wrestling, 141.
Wrinkles, 7.

Xanthin, 188.

Yeast, 178, 179, 255.
Yellow spot of eye, 342.

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