' '. &iMA
>~^
.
LIBRARY
OF THE
UNIVERSITY OF CALIFORNIA.
IFT OF
b,Q C
BIOLOGY
LIBRARY
:
Class
THE VISCERA IN POSITION.
TREATISE
ON
PHYSIOLOGY AND HYGIENE
FOR
EDUCATIONAL INSTITUTIONS AND GENERAL
READERS.
FULLY ILLUSTRATED.
BY
JOSEPH C. HUTCHISON, M. D.,
President of the New York Pathological Society, Vice-President of the New York
Academy of Medicine, Surgeon to the Brooklyn City Hospital, late President
of the Medical Society of the State of New York, etc.
NEW YORK :
CLARK & MAYNARD, PUBLISHERS,
5 BARCLAY STREET.
1880.
BIOLOGY
LIBRARY
G
Copyright, 1875, CLARK & MAYNARD.
TO MY WIFE,
WHOSE SYMPATHY HAS, FOR MORE THAN TWENTY YEARS, LIGHTENED THE
CARES INCIDENT TO
AN ACTIVE PROFESSIONAL LIFE,
THIS HUMBLE VOLUME
IS AFFECTIONATELY INSCRIBED
183669
PREFACE.
THIS work is designed to present the leading facts and principles
of human Physiology and Hygiene in cle^x and concise language,
so that pupils in schools and colleges, and readers not familiar with
the subjects, may readily comprehend them. Anatomy, or a de-
scription of the structure of an organ, is of course necessary to the
understanding of its Physiology, or its uses. Enough of the former
study has, therefore, been introduced, to enable the pupil to enter
intelligently upon the latter.
Familiar language, as far as practicable, has been employed,
rather than that of a technical character. With a view, however,
to supply what might seem to some a deficiency in this regard, a
Pronouncing Glossary has been added, which will enable the in-
quirer to understand the meaning of many scientific terms not
in common use.
In the preparation of the work the writer has carefully examined
all the best material at his command, and freely used it ; the special
object being to have it abreast of the present knowledge on the sub-
jects treated, as far as such is possible in a work so elementary as
this. The discussion of disputed points has been avoided, it being
manifestly inappropriate in a work of this kind.
Instruction in the rudiments of Physiology in schools does not
necessitate the general practice of dissections, or of experiments upon
animals. The most important subjects may be illustrated by draw-
4 PREFACE.
ings, such as are contained in this work. Models, especially those
constructed by Auzoux of Paris, dried preparations of the human
body, and the organs of the lower animals, may also be used with
advantage.
The writer desires to acknowledge his indebtedness to R. M
WYCKOPF, M.D., for valuable aid in the preparation of the manu-
script for the press; and to R. CRESSON STILES, M.D., a skilful
microscopist and physician, for the chapter " On the Use of the
Microscope in the Study of Physiology." Mr. AVON C. BURNHAM,
the well-known teacher of gymnastics, furnished the drawing or
tl-3 parlor g3^mnasium and the directions for its use.
UNIVERSITY f
CONTENTS.
CHAPTER I.
PAGE
THE FRAMEWORK OF THE BODY , 15
The Bones Their form and composition The Properties of Bone The
Skeleton The Joints The Spinal Column The Growth of Bone
The Repair of Bone.
CHAPTER II.
THE MUSCLES 26
The Muscles Flexion and Extension The Tendons Contraction-
Physical Strength Necessity for Exercise Its Effects Forms of
Exercise Walking Riding Gymnastics Open-air Exercise
Sleep Recreation.
CHAPTER III.
THE INTEGUMENT, OR SKIN 4"
The Integument Its Structure The Nails and Hair The Complexion
The Sebaceous Glands The Perspiratory Glands Perspiration
and its uses Importance of Bathing Different kinds of Batlis
Manner of Bathing The Benefits of the Sun Importance of
Warm Clothing Poisonous Cosmetics.
CHAPTER IV.
THE CHEMISTRY OF FOOD 53
Tne Source of Food Inwganic Substances Water Salt Lime Iror
Organic Substances Albumen, Fibrin, and Casein The Fats v
Oils The Sugars, Sfa-?ch, and Gu,m Stimulating Substano*
.T r efenty of a Regulated Diet.
CONTENTS.
CHAPTER V.
PAGB
FOOD AND DRINK 64
Necessity for Food Waste and Repair Hunger and Thirst Amount
of Food Renovation of the Body Mixed Diet Milk Eggs Meat
Cooking Vegetable Food Bread TJie Potato Fruits Purity
of Water Action of Water upon Lead Coffee, Tea, and Chocolate
Effects of Alcohol.
CHAPTER VI.
DIGESTION 80
The Principal Processes of Nutrition The General Plan of Digestion
Mastication The Teeth Preservation of the Teeth Insalivation
The Stomach and the Gastric Juice The Movements of the
Stomach Gastric Digestion The Intestines The Bile and Pan-
creatic Juice Intestinal Digestion Absolution by means of Blood-
vessels and Lacteals The Lymphatic or Absorbent System The
Lymph Conditions which affect Digestion The Quality, Quan-
tity, and Temperature of the Food The Influence of Exercise and
CHAPTER VII.
THE CIRCULATION 101
The Blood Its Plasma and Corpuscles Coagulation of the Blood The
Uses of the Blood Transfusion Change of Color The Organs of
the Circulation The Heart, Arteries, and Veins The Cavities
and Valves of the Heart Its Vital Energy Passage of the Blood
through the Heart The Frequency and Activity of its Movements
The Pulse The Spygmograph The Capillary Blood-vessels The
Bate of the Circulation Assimilation Injuries to the Blood-vessels.
CHAPTER VIII.
RESPIRATION 123
The Objects of Respiration The Lungs The Air- Passages The Move-
ments of Respiration Expiration and Inspiration The Frequency
of Respiration Capacity of the Lungs The Air we Breathe
Changes in the Air from Respiration Changes in the Blood In-
terchange of Oases in the Lungs Comparison between Arterial and
CONTENTS. 7
Venous Blood Respiratory Labor Impurities of the Air Dust
Carbonic Acid Effects of Impure Air Nature's Provision for
Purifying the Air Ventilation Animal Heat.
CHAPTER IX.
PAG*
THE NERVOUS SYSTEM 1 48
Animal and Vegetative Functions Sensation, Motion, and Volition
The Structure of the Nervous System The White and Gray Sub-
stances The Brain Its Convolutions The Cerebellum The Spi-
nal Cord and its System of Nerves The Anterior and Posterior
Roots The Sympathetic System of Nerves The Properties of Nerv-
ous Tissue Excitability of Nervous Tissues The Functions of the
Spinal Nerves and Cord The Direction of the Fibres of the Cord
Reflex Activity and its Uses The Functions of the Medulla Oblon-
gata and the Cranial Ganglia The Reflex Action of the Brain.
CHAPTER X.
THE SPECIAL SENSES 177
The Production of Sensations Variety of Sensations General Sensi-
bility Pain and its Function Special Sensation, Touch, Taste,
Smell, Sight, and Hearing The Hand, the Organ of Touch The
Sense of Touch Delicacy of Touch Sensation of Temperature and
Weight The Tongue the Organ of Taste The Nerves of Taste
The Sense of Taste, and its Relations with the other Senses The
Influence of Education on the Taste The Nasal Cavities, or the
Organs of Smell The Olfactory Nerve The Uses of the Sense of
Smell The Sense of Sight Light The Optic Nerve The
Eyeball and its Coverings The Function of the Iris The
Sclerotic, Choroid, and Retina The Tears and their Func-
tion The Movements of the Eyeball The Function of Ac-
commodation The Sense of Hearing and Sound The Ear, or the
Organ of Hearing The External, Middle, and Internal Ear.
CHAPTER XI.
THE VOICE 227
Voice and Speech The Larynx, or the Organ of the Voice The Vocal
Vords The Laryngoscope The Production of the Voice The Use
of me, Tongue The different Varieties of Voice The Change of
Voice Its Compass - Purity of Tone Ventriloquy,
8 CONTENTS.
CHAPTER XII.
PAGE
THE USE OP THE MICROSCOPE IX THE STUDY OF
PHYSIOLOGY 236
The Law of Tissues Necessity of the Microscope Different kinds of
Microscopes Additional Apparatus Preliminary Studies The
Study of Human Tissues Tissues of the Inferior AnimaU Incen-
tives to Study.
APPENDIX.
POISONS AND THEIR ANTIDOTES , . , . . . . * 247
GLOSSARY 252
LIST OF ILLUSTRATIONS
FRONTISPIECE,
VISCERA IN POSITION, >
1. Section of bone, . . . . . . 17
2. Structure of bone, magnified, . . . . 17
3. The skeleton, 18
4. Cells of cartilage, 20
5. Elbow-joint, 21
6. Spinal column, ........ 22
7. The muscles, 24
8. Muscular tissue, magnified, ..... 25
9. Biceps muscle of the arm, .... .26
10. View of knee-joint, 27
11. Appliance for strengthening the muscles, . . . 35
12. Appliance for strengthening the muscles, ... 35
13. Parlor gymnasium, ....... 36
14. Root and transverse section of hair, magnified, . . 43
15. Granules of potato starch, . . . . .61
1 6. Section of the trunk, 81
17. Section of a tooth, 82
1 8. Section of the jaws, ....... 82
19. Section of the jaws right side, 84
20. Structure of a salivary gland, 87
21. Head of a horse, showing salivary gland, etc. . . 87
22. Section of chest and abdomen, 90
23. Organs of digestion, 91
24. The lacteals, \ 97
25. Blood corpuscles, 102
26. Blood corpuscles of man and lower animals, . . " 103
27. Circulation of the blood, . . 108
10 LIST OF ILLUSTRATIONS.
FIG. PAGE
28. Heart and large vessels, ...... 109
29. Section of the heart, 1 10
30. Form c. the pulse, 116
3 1 . Valves of the veins, 117
32. Web of frog's foot, magnified, 119
33. Circulation in a frog's foot, 119
34. Organs of the chest, 124
35. Larynx, trachea, and bronchial tubes, . . . . 125
36. Diagram of the structure of the air-cells, . . . 125
37. Section of the lungs, . . . . . . .126
38. Section of mouth and throat, . . . . . 127
39. Ciliated cells, 128
40. Cerebro-spinal system, . . . . . . 151
41. Upper surface of the cerebrum, . . . . . 153
42. Vertical section of the brain, 154
43. Base of the brain, . . . . . . . . 155
44. Brain and spinal cord, 156
45. Sense of touch, 185
46. Section of nasal cavity, . . . . . . 193
47. Front view of the eye, . 200
48. Vertical section of eye, 202
49. Diagram for blind point of eye, ..... 207
50. Retinal image, 210
51. Different shapes of the globe of the eye, . . .212
52. Function of accommodation, . . . . . 214
53. Diagram of the ear, 218
54. Section of the ear, 221
55. Section of larynx and trachea, 229
56. View of vocal cords by the laryngoscope, . . . 232
57. Different positions of vocal cords, 232
58. Simple microscope, . .... 238
59. Compound microscope, 239
60. Household microscope, 240
61. Popular microscope., 241
INTRODUCTION.
THE Human Body is the abode of an immortal spirit,
and is the most complete and perfect specimen of the
Creator's handiwork. To examine its structure, to ascer-
tain the uses and modes of action of its various parts,
how to protect it from injury, and maintain it in a
health/ condition, is the design of this work.
The departments of knowledge which are concerned
in these investigations, are the science of Human Physi-
ology and the art of Hygiene.
PHYSIOLOGY treats of the vital actions and uses of the
various parts of living bodies, whether vegetable or ani-
mal. Every living thing, therefore, has a Physiology.
We have a Vegetable Physiology, which relates to plants;
and an Animal Physiology, relating to the animal king-
dom. The latter is also divided into Comparative Physiol-
ogy, which treats of the inferior races of animals, and
Human Physiology, which teaches the uses of the various
parts of the human body.
HYGIENE, or the art of preserving health, is the practi-
cal use of Physiology. It teaches us how to cultivate our
bodily and mental powers, so as to increase our strength
and to fit us for a higher enjoyment of life. It also shows
us how to prevent some of the accidents which may befall
the body, and to avoid disease. It is proper that we should
I'Z INTRODUCTION.
understand the construction and powers of our bodies; but
it is our duty, as rational beings, to know the laws by which
health and strength may be maintained and disease warded
off.
There are various means by which we gain important
information respecting the Physiology of man. Plants
aid us in understanding the minute structure of the hu-
man body, its circulation, and absorption. From inferior
animals we learn much in respect to the workings of the
different organs, as we call those parts of the system which
have a particular duty to perform. In one of them, as in
the foot of the frog, we can study the circulation of the
blood; in another, we can study the action of the brain.
By vivisection, or the laying bare of some organ of a
living animal, we are able to investigate certain vital
processes which are too deeply hidden in the human body
to be studied directly. This is not necessarily a cruel
procedure, as we can, by the use of anaesthetics, so blunt
the sensibility of the animal under operation, that he
need not suffer while the experiment is being performed.
There are other means by which we gather our informa-
tion. There are occasionally men, who, from some acci-
dent, present certain parts, naturally out of view, in
exposed positions. In these cases, our knowledge is of
much greater value than when obtained from creatures
lower in the scale of being than man.
We are greatly aided, also, by the use of various instru-
ments of modern invention. Chief among these is the
microscope, which is, as we shall learn hereafter, an ar-
rangement and combination of lenses in such a way as
greatly to magnify the objects we wish to examine.
INTRODUCTION. 13
We have much to say of Life, or vital activity, in the
course of our study of Physiology; but the most that we
know of it is seen in its results. What Life is, or where its
precise position is, we are not able to determine. We dis-
cover one thing, however, that all the parts of the body
are united together with wonderful sympathy, so that one
part cannot be injured and other parts not suifer damage.
It is further evident that all organs are not equally im-
portant in carrying on the work of Life; for some may
temporarily suspend their action, without serious results
to the system, while others must never cease from acting.
Yet there is nothing superfluous or without aim in our
frames, and no part or organ can suifer harm without
actual loss to the general bodily health. On this point
Science and Holy Writ strictlv
PHYSIOLOGY,
AND
HYGIENE.
CHAPTER I.
THE FRAMEWORK OF THE BODY.
The Bones Their Form and Composition The Properties of Bone-~
The Skeleton TJie Joints The Spinal Column The Growth of
Bone The Repair of Bone.
1. The Bones. The framework which sustains the
human body is composed of the Bones. The superstructure
consists of the various organs on which the processes of
life depend. These organs are soft and delicately formed,
and, if unprotected, would, in most cases, rapidly be de-
stroyed when subjected to violence, however slight. The
bones, having great strength and power of resistance, afford
the protection required. (Read Note i, end of Chapter)
2. The more delicate the organ, the more completely does
Nature shield it. For example : the brain, which is soft in
structure, is enclosed on all sides by a complete box of bone;
the eye, though it must be near the surface of the body
to command an extensive view, is sheltered from injury
within a deep recess of bone; the lungs, requiring freedom
of motion as well as protection, are surrounded by a large
case of bone and muscle. The bones serve other useful
purposes. They give permanence of form to the body, by
1 . The framework of the body ? The superstructure ? Softness and delicacy
of tho organs ? How protected ?
2. The more delicate the organ ? Example in relation to the brain ? The eye ?
The lungs ? The services performed by the bones ?
16 THE FRAMEWORK OF THE BODY.
holding the softer parts in their proper places. They
assist in movement, by affording points of attachment to
those organs which have power of motion the muscles.
3. The Form and Composition of the Bones.
Their shape and size vary greatly in different parts of the
body, but generally they are arranged in pairs, one bone for
each side of the body. They are composed of both mineral
and animal substances, united in the proportion of two
parts of the former to one of the latter; and we may sep-
arate each of these substances from the other for examina-
tion. First, if we expose a bone to the action of fire,
the animal substance is driven off, or " burned out." We
now find that, though the shape of the bone is perfectly
retained, what is left is no longer tough, and does not sus-
tain weight as before. Again, we may remove the mineral
portion, which is a form of lime, by placing a bone into a
dilute acid. The lime will be dissolved out, and the shape
of the bone remain as before; but now its firmness has
disappeared, and it may be bent without breaking.
4. If, for any reason, either of these ingredients is dis-
proportionate in the bone during life, the body is in
danger. The lime is useful in giving rigidity of form,
while the animal substance insures toughness and elas-
ticity. By their union, we are able to withstand greater
shocks and heavier falls than would be possible with
either alone. In. youth, the period of greatest activity,
the animal constituent is in excess: a bone then does
not break so readily, but, when broken, unites with great
rapidity and strength. On the other hand, the bones of
old persons are more easily broken, and in some cases fail
to unite. The mineral matter being then in excess, indi-
cates that the period of active exertion is drawing to a
close. (Read Note 2, end of Chapter)
3. Their shape and size ? Of what composed? Possibility of being separated ?
Effect of fire ? Of dilute acid ?
1 . Effect of deficiency of ingredient ? Usefulness of the lime ? Of the anima.
Hiltr-iance? Effect of their union ? Condition, in youth ?
THE FRAMEWORK OF THE BODY.
1?
5. The Structure of the Bones. If we examine one
of the long bones, which has been sawn through length-
wise, we observe that it is admirably fashioned for affording
A.. Longitudinal B. Transverse section of bone.
FIG. 1. SECTION OF BONE.
lightness as well as strength (Fig. 1). Its exterior is hard
and resisting, but it is porous at the broad extremities,
while through the central portion
there is a cavity or canal which con-
tains an oily substance, called marrow.
Let us now take a thin section of
bone, and examine it under the mi-
croscope; we discover that it is pierced
by numerous fine tubes (Fig. 2),
about which layers of bone-substance
are arranged. Accordingly, though a
bone be as hard as stone externally, it
is by no means as heavy as stone, by
reason of its light interior texture.
Another element of power is found in
the curved outline of the bones. The pis 2
curved line is said to be " the line of structure of bone en-
beauty," as it certainly is the line of larged '
strength, and is uniformly employed
in the bones whose position exposes them to accident.
5. In what respect admirably faehioned ? Its formation? Microscopic exam
npon ? The inference? " Line of beauty ?"
FIG. 3. THE SKELETON
THE FRAMEWORK OF THE UODY. 19
6. The Skeleton. The number of bones in the human
body exceeds two hundred. When these are joined together
in the proper places, they form what is termed the Skeleton
(Fig. 3). It embraces three important cavities. The first,
surmounting the frame, is a box of bone, called the skull;
below this, is a bony case, or " chest ;" anl lower down is
a bony basin, called the pelvis. The two latter compose
the trunk. The trunk and skull are maintained in their
proper relations by the " spinal column." Branching from
the trunk are two sets of limbs: the arms, which are
attached to the chest by means of the " collar-bone" and
" shoulder-blade ;" and the legs, directly joined to the lower
part of the trunk. (Read Note 3, end of Chapter^
7. The cavities of which we have spoken, are designed
for the lodgment and protection of the more delicate and
perishable parts of the system. Thus, the skull, together
with the bones of the face, shelters the brain and the
organs of four senses sight, hearing, smell, and taste.
The chest contains the heart, lungs, and great blood-ves-
sels, while the lower part of the trunk sustains the liver,
stomach, and other organs
I 8. The Joints. The point of union of two or more
bones forms a joint or articulation, the connection being
made in various ways according to the kind and amount
of motion desired. The movable joints are compacted
together by certain strong fibrous bands, called ligaments.
These ligaments are of a shining, silvery whiteness, and
very unyielding; so much so, that when sudden violence
is brought to bear in the vicinity of a joint, the bone to
which a ligament is attached may be broken, while the
ligament itself remains uninjured. When this connect-
ing material of the joints is strained or lacerated by an ac-
6. Number of bones ? Skeleton ? The skull ? Chest ? The trunk ? The trunk
and skull, how maintained ? What of the arms ? Legs ?
7. Design of the cavities ? Give the examples.
8. Joint or articulation ? Movable joints, how compacted? The ligaments of
the movable joint* ? What is a sprain ? Consequence of a serums eprain?
THE FRAMEWORK OF THE BODY.
cident, a "sprain" is the consequence, j An injury of this
sort may be, and frequently is, quite as serious as the
breaking of a bone. (Read Note 4, end of Chapter^
9. The ligament, then, secures firmness to the joint;
it must also have flexibility and smoothness of motion.
This is accomplished by a beautiful mechanism the perfec-
tion of which is only feebly imitated by the most ingenious
contrivance of man. [T]ie ends of the bones are covered
by a thin layer of cartilage/ which being smooth and elas-
tic, renders all the movements of the joint very easy. In
addition to this, there is an arrangement introduced for
" lubricating" the joint, by means of a delicate sac con-
taining fluid. This fluid is constantly supplied in small
quantities, but only so fast as it is used up in exercise.
In appearance, it is not unlike the white of an egg, and
hence its name synovia, or egg-like.
10. Thus, we observe, that two
very different substances enter into
the composition of a joint. The
ligament, very unyielding, affords
strength, while the cartilage, elastic
and moist, gives ease and smooth-
ness of motion. The amount of
motion provided for varies greatly
in different joints. In some there is
none at all, as in the skull, where
one bone is dove-tailed into another
by what are termed j^wres.; Others
have a hinge-like motion, such as
FIG. 4.-CELLS or CARTHAGE. thoge of the elbow? wns t, ankle,
and knee ; the most complete of these being the elbow-
joint (Fig. 5). Belonging to another class, the ball-and-
9. Office of the ligament ? What must it have ? How accomplished ? Describe
it. Synovia ?
1 0. What do we observe as regards the composition of a joint ? The lie 1 roent
and cartilage? What varies? Example of tho skull ? Other example* ? The
bal]-and- c orkot i^lnt?
THE FRAMEWORK OF THE BODY.
socket joint, is that at the shoulder, possessing a freedom
of motion greater than any other in the body.
PIG 5. ELBOW JOINT. A, Bone of the arm ; B, C, Bones of the fore-arm.
11. The Spinal Column. The spinal column is often
spoken of as the " back-bone," as if it were a single bone,
while, in reality, it is composed of a chain of twenty-six
small bones, called vertelrce. The spinal column is a
wonderful piece of mechanism. It not only connects the
important cavities of the body, as has already been shown,
but, also, itself forms a canal, which contains the spinal
cord. The joints of the vertebrae are remarkable for the
thick layers of cartilage which separate the adjacent sur-
faces of bone. The amount of motion between any two
of these bones is not great; but these little movements,
taken together, admit of very considerable flexibility, in
several directions, without endangering the supporting
power of the column.
1 1 . What is the spinal column ? What docs it connect and form ? Joints cf
the vertebra ? Amount of motiou? Result?
22 THE FKAMEWOKK OF THE BODY.
12. The abundant supply of iiitervertebral cartilage has
another important use, namely, it adds greatly to the
elasticity of the frame. It is due, in part,
to this elastic material, and in part to the
frequent curves of the spine, that the brain
and other delicate organs are protected from
the shock of sudden falls or jars. During
the day, the constant pressure upon these
joints, while the body is erect, diminishes
the thickness of the cartilages; so that a
person is not so tall in the evening as in
the morning. The effects of this compres-
sion pass away when the body reclines in a
horizontal position. (Read Note 5, end of Chapter)
13. The Growth of Bone. Bone, like
all the other tissues of the body, is con-
stantly undergoing change, old material
being withdrawn, and new particles taking
their place. This has been shown conclu-
sively by experiments. If an animal be fed
with madder a red coloring matter for a
day or two, the bones soon become tinged ;
then, if the madder be discontinued for a
few days, the original color returns. If, how-
ever, this material be alternately given and
withheld, at short intervals, the bone will
be marked by a succession of red and white
rings. In very young animals, all the bones
become colored in a single day; in older
FIG. 6. THE ones, a longer time is required. The process
SPINAL COLUMN. rt , *.* ^
of waste and repair, therefore, is constantly
taking place in this hard substance, and with astonishing
rapidity.
12. Elasticity of the frame ? Protection of the brain from shocks Tallness
of persons? Effects of reclining ?
13. Change in hone? Example- animal and madder. Rapidity of change' in
color? W*te and repair !
THE FRAMEWORK OF THE BODY. 23
J 14. The Repair of Bone. Nature's provision for
^uniting broken bones is very complete. At first, blood is
\ poured out around the ends of the bone, as a result of
the injury. This is gradually absorbed, and gives place
to a watery fluid, which, thickening from day to day, ac-
quires, at the end of two weeks, the consistency of jelly.
This begins to harden, by a deposit of new bone-substance,
until, at the expiration of five or six weeks, the broken
bone may be said to be united. It is, however, still fragile,
and must be used carefully a few weeks longer. The
process of hardening continues, and months must pass
hefore the union can be said to be complete. (Read Note 6.)
QUESTIONS FOR TOPICAL REVIEW.
PAGE
1. What useful purposes do the bone? serve *>. 15, 16
2. State what you can of tho composition of the bones 16
8. Of the usefulness of lime in the bones 16
1. Of the usefulness of animal substance in the bones 16
5. State what you can of the structure of the bones 17
6. Of the strength belonging to the bones 15. 16, 17
7. What is in eant by the human skeleton 1 19
8. Give-a description of .its construction , ; Tvr-rT-rj^^. 18
9. What is meant by a j oint in the human frame ? 19
K). State what you can of the movable joints 19, 20
11. What office is performed by the ligaments of the joints ? 19, 20
12. What by the cartilage at the joints ? 20
13. What movable joints are there ? 20, 21
14. Describe the construction of the spinal column. 21
15. What properties and powers does the spinal column possess ? 21, 22
16. When is a person taller than at other times ? 22
17. Give the reason for this 22
18. What can you state of the growth of bone? 22
19. Describe the process by which a broken bone is repaired S3
NOTES.
1. Self-knowledge (p. 15, ^ 1). "It has been said with truth that the
human mind, which can survey the heavens and calculate the motion and density
of the stars, finds itself confounded when, returning from these distant journey-
ings, it enters its own dwelling-place the body. Man t? own organization is still
among those mysteries of nature which he is least able to penetrate, in spite of his
incessant efforts to lift the veil which hides it. In all ages he has sought to know
himself. In all times he has studied the relations between his own existence and
that of the world, and those universal influences which, though evident to him,
are nearly all inexplicable in their action upon living beings. 11 ^ Pileuron the
Human Body.
2. Some Properties of Bone (p. 16, 1 4). The power of bone to resist
decay is remarkable. Fossil bones deposited in the ground long before the appear-
ance of man upon the earth have been found by Cuvier exhibiting a considerable
portion of cartilage. The jaw of the Cambridge mastodon contained over forty
per cent, of animal matter enough to make a good glue and others about the
same. From this we see that a nutritious soup might be made from the bones of
animals that lived .before the creation of man. The teeth resemble bone in their
structure, but resist decay longer ; they are brought up by deep-sea dredging,
when all other parts of the animal have wasted away. The bones differ at differ-
ent ages, and under different social conditions. In the disease called 'rickets,'
quite common among the ill-fed children of the poor in Europe, but somewhat
rare in America, there is an inadequate deposit of the mineral substance, render-
ing the bones so flexible that they may be bent almost like wax. In females and
weak men the bones are light and thin, while in a powerful frame they are dense
and heavy. Exercise is as necessary to the strength of bone as to the strength of
muscle ; if a limb be disused, from paralysis or long sickness, the bones lose in
weight and strength as well as the soft parts. Bone is said to be twice as strong
as oak, and, to crush a cubic inch of it, a pressure equal to 5,000 pounds is requi-
site. Dunglison (in part)."
3. Two Forms of Skeleton among Animals (p. 19, 1 6). "The
solid basis on which all the soft organs of the body rest is the skeleton. In the
human body the skeleton is composed of a number of bones, each of which has a
distinct name. In the animal kingdom there are two distinct forms of skeletons ;
the one which is found chiefly in the lower animals is outside, and covers the soft
parts, and is called an exo-skeleton. Examples of this kind of skeleton are seen
in crabs, lobsters, insects, and the shells of mollusca, as oysters, mussels, and
whelks. The shells of these animals are mostly composed of carbonate of lime.
Fishes possess an internal skeleton ; and all the classes of animals above them, as
reptiles, birds, and mammals, possess internal or endo-skeletons." Lankesler's
Manual of Health.
4. How Joints may be Injured (p. 20, 1 8)." All the joints are
liable to dislocation that is, bein<r ' put out ' of their place. Owing to the shal-
lowness of the cavity at the shoulder, this joint is frequently dislocated ; and this
sometimes happens with the thigh, but not so often, as the cup in which the
femur moves is much deeper. Joints which have been dislocated should at once
be 'set ; ' but now that you have seen how liable you are to accident, I hope you
will be careful not to indulge in too violent or rough exercise, by which you
might not only dislocate the joints, and so in time weaken them, but might also
break the bones, and perhaps become crippled for life. Many children have the
habit of pulling their fingers so as to make them 'crack.' This is exceedingly
wrong, for it is to a certain extent pulling the joints out of their sockets, and this
NOTES.
may so loosen the parts as to cause permanent injury." Davidson's " Our
Bodies."
5. Some Causes of Curvature of ;3ie Spine (p. 22, [ 12). "Much as
horse-riding is valued on account of the healthful character of its exercise, yet
an over-indulgence by young ladies owing to the oblique position in which the
female form rests in the side-saddlewill cause the spine to become curved."
To avoid this, it is important for young ladies to ride occasionally on the opposite
side of the horse. Another frequent cause of curvature of the spine is the use of
the sewing machine, especially among needy seamstresses, whose bread frequently
depends on the almost unceasing labor of their hands and feet, while sitting in
a constrained position. Soon after croquet became a favorite amusement among
the fashionable young ladies of England, it was noticed that the bent position
assumed during the time the mallet is used caused a certain deformity, to which
was given the name of the "croquet curvature." The use of high heels on
boots and shoes of children, by throwing the weight of the body too far forward,
on the front of the foot, and destroying the natural poise of the body, acts an
important part in causing the spine to become crooked. By many this crooked
condition is considered to be largely a school-room disease, for the reason that
children often are compelled to sit, and write or study, in a bent posture ; but there
must be other causes for it, since it has been found that it is almost exclusively a
female deformity. Over eighty-four per cent, of the cases is stated by one writer
to be among girls. But inasmuch as the majority of these cases begin during the
years of schooling from the ages of six to fourteen great attention should be
paid to the position of the body during school hours, and ample opportunity
should be offered, by a regular system of gymnastics, to counteract all the evil
influences of the school-room posture. Heather- Mgg on Deformities (in part).
6. Tlie Management of a Broken Limb (p. 23, If 14)." Frac-
tures are usually met with when the person is dressed. Therefore, unless there
is bleeding, or something to call for immediate exposure and examination of the
damaged part, do not be in a hurry to remove the clothes. If the arm be hurt,
extemporize a sling from a neck-handkerchief or some other article of dress, and
support the arm from elbow to wrist, tying the ends of the handkerchief in a
knot over the coat-collar behind. If the thigh or leg be in pain, fasten the injured
limb to its fellow by a cravat bandage or two, and take care that they lie side by
side, and on the same level ; or fasten outside the clothes some temporary sup-
port, a piece or two of straight stick, with a bandage, and then remove the sufferer
quietly and carefully to some house near at hand. If medical aid be available,
send for it without any delay ; and be careful, if in the country, and so at some
distance from the doctor's honse, to forward a clear statement as to the appar-
ent nature of the accident, which limb is hurt, and where and how it happened.
Let this statement, too, be in writing, it possible. It may well happen, however,
that skilled assistance cannot be had, and .n this case the patient should be
undressed quietly and cautiously. It will be far better to slit up the dress on the
arm or leg with a pair of scissors than to pull it off; but however the covering
of the injury may be managed, it must be done very slowly and gently, and the
limb should be supported so as to prevent jarring and shaking to the damaged
part. It must be carefully kept, too, in a right direction, for otherwise some sharp
splinter of bone may penetrate the hitherto unwounded skin." First Ildp in
Accidents and Sickness.
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THE MUSCLES.
FIG. 7. THE MUSCLES.
THE MUSCLES.
CHAPTER II.
THE MUSCLES.
The Muscles Flexion and Extension The Tendons Contraction ^
Physical Strength Necessity for Exercise Its Effects Forms of
Exercise Walking Riding Gymnastics Open-air Exercise
Sleep Recreation.
1. The Muscles. The great mass of the body exter-
nal to the skeleton, is composed of the flesh, or Muscles,
which largely determines its outline and weight. The
muscles are the organs of motion. Their number is
about four hundred, and to each of them is assigned a
separate and distinct office. They have all been studied,
one by one, and a name given to each, by the anatomist.
Each is attached to bones which it is designed to move.
A few are circular in form, and enclose cavities, the size
of which they diminish by contraction.
2. If we examine a pl3ce of flesh, we observe that it is
soft, and of a deep red color. Its structure appears to be
composed of layers
and bundles of small
fibres. Let us fur-
ther examine these
fibres under the mi-
croscope. We now
discover that they
are, in turn, made up
of still finer fibres,
or fibrillce : these are
FIG. 8 MUSCULAB TISSUE. . ,
a, 5, Striped muscular fibres: c, The same more Seen in J^ Ig. O. Ine
highly magnified. fibreg ^ Q beauti f ully
J , What arc the muscles ? Their number ? The design of most of them F Of
a few*
2. The structure of flesh? Its color, etc.? The composition of the fibres ':
H<:w marked?
THE MUSCLES.
marked by parallel wavy lines, about ten thousand to an
inch, which give the fibre its name of the striped muscular
fibre. All of the voluntary muscles present this appearance.
3. Flexion and Extension. The muscles are, for
the most part, so arranged in pairs, or corresponding
sets, that when motion is produced in one direction by
one set, there is, opposite to it, another
muscle, or group of muscles, which
brings the limb back to its place. When
they act alternately, a to-and-fro move-
ment results. When a joint is bent, the
motion is called flexion ; and when it is
made straight again, it is called exten-
sion. When both sets act equally, and
at the same moment, no motion is pro-
duced, but the body or limb is main-
tained in a fixed position: this occur?
when we stand erect. The muscles
which produce extension are more pow-
erful than thoso opposite to them.
4. The muscles are also distinguished,
on the other hand, as the voluntary
and involuntary muscles, according as
they are, or are not, under the control
of the will. The heart is ^n example of
the involuntary variety. We cannot
change its action in the least by an
FIG. 9. A, Biceps mus- .,, -,.. ,
cie of the arm: B, c, effort oi the will. When w^ sleep, and
Its tendons. .,, ,11 ,
the will ceases to act, the heart contin-
ues to beat without cessation. The voluntary muscles,
on the other hand, are such as are used only when we wisn
or will to use them as the muscles of the hand or arm
( Fig. 9 ) . (Read Note I , end of Chapter^
3. Arrangement of the muscles ? Their action ? Flexion and extenson ? Ac-
tion of the muscles when we stand erect ?
4. Kinds of muscles ? The voluntary ? Involuntary? The heart? G ; V > l c'
example. The hand ? Arm -
THE MUSCLES.
5. The Tendons. Tendons, or sinews, are the ex-
tremities of muscles, and are compactly fastened upon
bone. They are very strong, and of a silvery whiteness.
They may be felt just beneath the skin, in certain parts
of the body, when the muscles are being used, as at the
bend of the elbow or knee. The largest tendon of the
body is that which is inserted into the heel, called the
tendon of Achilles, after the hero of the Grecian poet, the
fable relating that it was at this point that he received
his death- wound, no other part of his body being vulner-
able. The muscles which extend into the leg unite to
FIG. 10. VIEW OF KNEE-JOINT. A. Thigh bone: B, Knee-pan: C, D, Leg bones.
form a single and very powerful tendon, and enclose a
small bone called the knee-pan, which, acting like a pul-
ley, greatly increases their power, and at the same time
protects the front of the knee-joint (Fig. 10).
6. Muscular Contraction. The muscles, when acted
upon by the appropriate stimulus, contract, or so change
5. What are the tendons or sinews ? Their strength ? Color ? Location ?
Tendon of Achilles ? The fable ? Muscles of the leg ?
6. Contraction of the muscles ? Bending of the arm or finger ? Other agencies ?
Automatic movements ? In cold-blooded animals ?
2$ THE MUSCLES.
their shape, that their extremities are brought nearer to-
gether. The bending of the arm, or of a finger, is eifected
in this manner, by the will; but the will is not the only
means of producing this effect. Electricity, a sharp blow
over a muscle, and other stimuli, also cause it. Contrac-
tion does not always cease with life. In man, after death
from cholera, automatic movements of hands and feet
have been observed, lasting not less than an hour. In
certain cold-blooded animals, as the turtle, contraction
has been known to take place for several days after the
head has been cut off.
7. The property which, in muscle, enables these move-
ments to take place is called contractility. If we grasp a
muscle while in exercise (for example, the large muscle in
the front of the arm), we notice the alternate swelling and
decrease of the muscle, as we move the forearm to and fro.
It was at one time supposed that the muscle actually in-
creased in volume during contraction. This, however, is
not the case; for the muscle, while gaining in thickness,
loses in length in the same proportion; and thus, the
volume remains the same in action and at rest.
8. Contraction is not the permanent, or normal, state
of a muscle. It cannot long remain contracted, but after
a shorter or longer time, it wearies and is obliged to relax.
After a short rest, it can then again contract. It is for
this reason that the heart can beat all through life, night
and day, by having, as we shall hereafter see, a brief inter-
val of rest between successive pulsations. For the same
reason, it is more fatiguing to stand for any great length of
time in one position, than to be walking the same period.
9. Relative Strength of Animals. The amount
of muscular power which different animals can exert, has
7. Contractility? Give the illustration. What was supposed? What is the
case?
8. What further in relation to contraction ? Weariness of a muscle ? Beating
of the heart? Standing and walking?
9. Muscular power of animals ? How tested ? Man'* power? Horse's? The^
comparison ?
THE MUSCLES. 29
been tested by experiment. By determining the number
of pounds which an animal can drag upon a level surface,
and afterward comparing that with its own weight, we can
judge of its muscular force. It is found that man is able
to drag a little less than his own weight. A draught-horse
can exert a force equal to about two-thirds of his weight.
The horse, therefore, though vastly heavier than man, is
relatively not so powerful.
10. Insects are remarkable for their power of carrying
objects larger and heavier than themselves. Many of
them can drag ten, and even twenty times their weight.
Some of the beetles have been known to move bodies more
than forty times their own weight. So far, therefore, from
it being a fact that animals have strength in proportion
to their weight and bulk, the reverse of that statement
seems to be the law.
11. Physical Strength. The difference in strength,
as seen in different individuals, is not due to any original
difference in their muscles. Nature gives essentially the
same kind and amount of muscles to each person, and the
power of one, or the weakness of another, arises, in great
part, from the manner in which these organs are used or
disused.
12. Many authors complain of the physical degeneracy
of men at the present day, as compared with past genera-
tions. There is room for doubt as to the correctness of
this statement. Certain experiments have recently been
made with the metallic armor worn seven hundred years
ago, by which it is found that any man, of ordinary height
and muscular development, can carry the armor and wield
the weapons of an age supposed to be greatly our superior
in strength. When we consider that in those days, only
very strong men could endure the hardships of soldier-life,
10. Power of insects? Beetles? Give the conclusion.
1 1 . Difference in strength of individuals ? How caused ?
12. Complaint in relation to degeneracy? How true? HOW determined by
armor ? The fair supposition ?
30 THE MUSCLES.
it is fair to suppose that our age has not so greatly degen-
erated in respect to physical strength.
13. Importance of Exercise. Action is the law of
the living body. Every organ demands use to preserve
it in full vigor, and to obtain from it its best services.
The value of that training of the mind, which we call
education, is everywhere recognized. The child is early
put to school, and for many years continues to study, in
order that his brain, which is the great centre of mental
power, may act healthfully and with force. It is impor-
tant that the body, also, should receive its education by
exercise. This is especially true of persons belonging to
certain classes of society, whose occupation confines them
within doors, and requires chiefly brain-work.
14. Persons who are engaged in manual labor in the
open air obtain all the exercise necessary for bodily health
in their regular business : their need is more likely to be a
discipline or exercise of the mind. A perfect business oi
life, therefore, would be one which would combine both
physical and mental labor in their proper proportions-
If such a business were possible for all the human race, life
would thereby be vastly prolonged. Such is, in fact, to a
large extent, the occupation pertaining to one period of
life childhood. A part of the time is spent by the child
in improving his mind by study, and another part of the
time he has physical exercise in his games and sports.
15. The Effects of Exercise. Exercise consists in
a well-regulated use of the voluntary muscular system.
The effects, however, are not limited to the parts used.
Other organs, which are not under the control of the
will, are indirectly influenced by it. For instance, the
heart beats more rapidly, the skin acts more freely, and
13. Action ? Use of organs ? Training of the mind ? ' The child's brain ?
Education of the body ?
14:. Work in the open air? A perfect business? Thejxmseciuence of universal
perfect business ? Occupation of children ?
15. In what does exercise consist Effects of it ?
THE MUSCLES. 31
becomes hotter, as well as the parts beneath it, and the ap-
petite and power of digestion are increased. An increased
exhalation from the lungs and skin purifies the current of
the circulation, and the body as a whole thrives under its
influence. (Read Note 2, end of Chapter^
16. The immediate effect of exercise, however, is upon
the muscles themselves; for by use they become firm and
large, and increase in power. If we examine a muscle thus
improved by exercise, we find that its fibres have become
larger and more closely blended together, that its color is
of a darker red, and that the supply of blood-vessels has
increased. Without exercise the muscle appears thin,
flabby, and pale. On the other hand, excessive exercise,
without sufficient relaxation, produces in the muscle a
condition not very different from that which follows dis-
use. The muscle is worn out faster than nature builds it
up, and it becomes flabby, pale, and weak.
17. Violent exercise is not beneficial; and spasmodic
efforts to increase the muscular strength are not calculated
to secure such a result. Strength is the result of a gradual
growth, and is most surely acquired if the exercise be
carried to a point short of fatigue, and after an adequate
interval of rest. To gain the most beneficial results, the
exercise should be at regular hours, and during a regular
period. The activity of the exercise, and the time de-
voted to it must vary, of course, with the strength of the
individual, and should be carefully measured by it. (Note 3.)
18. Different Modes of Exercise. There are very
few who have not the power to walk. There is required
for it no expensive apparatus, nor does it demand a period
of preliminary training. Walking may 1)6 called the uni*
versal exercise. With certain foreign nations, the English
16. General effect upon the muscles? Special effect? Effects of junction?
Of excessive exercise ?
17. Of violent and spasmodic efforts? Strength, how attained? Give the
particulars.
18. What may walking be called ? What further IP PPI^ of walking?
32 THE MUSCLES.
especially, it is a very popular exercise, and is practised
habitually by almost every class of society ; by the wealthy
as well as by those who have no carriages; by women as
Well as by men.
19. Running, leaping, and certain other more rapid and
violent movements, are the forms of exercise that are
{nost enjoyed in childhood. For the child, they are not
too severe, but they may be so prolonged as to become
injurious. Instances have been recorded where sudden
death has resulted after violent playing, from overtaxing
the heart: for example, we have the case of a young girl
who, while skipping the rope, and endeavoring to excel
Jier playmates by jumping the greatest number of times,
fell dead from rupture of the heart.
20. Carriage-riding, as a means of passive exercise, is par-
ticularly well suited to invalids, and persons advanced in
life. Horseback exercise brings into use a greater number
of muscles than any other one exercise, and with it there
:s an exhilaration of feeling which refreshes the mind at the
same time. It is one of the manliest of exercises, but not
less suitable for women than for men. To be skilful in
riding, it is best to begin its practice in youth; but there
are very few kinds of exercise of which the same is not
equally true.
21. For those who live near streams or bodies of water,
there are the delightful recreations of boating, swimming,
and skating. Certain of these exercises have a practical
importance aside from and above their use in increasing
the physical vigor. This is especially true of boating and
swimming, since they are often the means of saving life.
Practice in these exercises also teaches self-reliance,
courage, and presence of mind. Persons who have become
proficient in these vigorous exercises are generally the ones,
1 9. What is said of running, and other hkc movements ? What, as related tc
uhildhood ? What instances are alluded to ? Example '(
20. Carriage-riding? Horseback-riding?
21. Boating, swimming, and skating?
THE MUSCLES. 33
who, in times of danger, are the quickest to act and the
most certain to do so with judgment.
22. Physical Culture. That form of exercise which
interests and excites the mind, will yield the best results ;
but to some persons no kind of exertion whatever is, at
first, agreeable. They should, nevertheless, make a trial
of some exercise, in the expectation that, as they be-
come proficient in it, it will become more pleasant. In
exercise, as many sets of muscles should be employed
as possible, open-air exercise being the best. Parlor
gymnastics, and the discipline of the gymnasium are
desirable, but they should not be the sole reliance for
physical culture. No in-door exercise, however excellent
in itself, can fill the place of hearty and vigorous activity
jl the open air. (Read Notes 5 and 6.)
r- 23. Gymnastic Exercises for Schools and Col-
leges. In the system of education among the ancients,
physical culture predominated. In ancient Greece, physi-
cal exercises in schools were prescribed and regulated by
law, and hence these schools were called gymnasia. At
the present time, on the contrary, this culture is almost
wholly unknown, as a part of the course of education, in
our schools and colleges. In a few of our institutions of
learning, however, physical exercises have been intro-
duced, with manifest advantage to the students, and they
form a part of the regular curriculum of exercises, as
much so as the recitations in geography, grammar, or
Greek. The good effect of the experiments, as shown in
improved scholarship as well as increased bodily vigor, in
the institutions where the plan has been tried, will, it is
hoped, lead to its universal adoption. We should then
hear less frequently of parents being obliged to withdraw
their children from school, because they become exhausted
22. What kind of exercise yields the best results? What advice is given ?
23- Physical culture among the ancients ? In Greece ? In schoo
at the present time ? Result to the body and mind ?
2*
34 THE MUSCLES.
or, perchance, have lost their health from intense and pro
tracted mental application.
r~ 24. Were gymnastics more common in our educational
institutions we should not so often witness the sad spectacle
of young men and women leaving our colleges and semi-
naries, with finished educations it may be, but with consti-
tutions so impaired, that the life which should be devoted
to the accomplishment of noble purposes must be spent in
search of health. Spinal curvatures, which, according to
the experience of physicians, are now extremely frequent,
especially among ladies, would give place to the steady
gait and erect carriage which God designed his human
creatures should maintain. (Read Note 4, end of Chapter^
J5. All the exercises necessary for the proper develop-
ment of the body may be obtained from the use of a few
simple contrivances that every one can have at home, at
little cost less by far than is spent for useless toys. Many
of these may be made available in the parlor or chamber,
though all exercises are far more useful in the open air. A
small portion of the day thus spent will afford agreeable
recreation as well as useful exercise. The Indian club, the
wand, the ring, and the dumb-bells answer ordinary pur-
poses very well. Illustrations are here introduced of a few
simple contrivances that may be useful for general exer-
cises, and are specially suitable for persons with weak
spines, or with spines that are the subject of lateral curva-
ture.
26. One of the simplest appliances for strengthening
the muscles of the spine, designed chiefly to exercise the
muscles on either side of the spine, consists of two wooden
handles attached to india-rubber cords, one of which is
attached to a hook made fast in the ceiling, or in the top
of the door-case ; and the other to another hook fastened
in the wall, door-post, or window-casing, about the height
The result of gymnastics in our colleges and other institutions of learning
THE MUSCLES.
of the shoulder. When traction is made with the left hand,
it exercises the muscles on the left side of the spine, while
FIG. 11.
those on the opposite side are left almost at rest, owing to
the oblique direction given to the shoulders when the right
hand grasps the horizontal cord. (This appliance will be
understood by referring to Fig. 13.)
36 THE MUSCLES.
27. Fig. 11 shows an appliance consisting of two strong
elastic cords, with handles, secured to a hook in the floor,
so arranged that the patient has to stoop forward to reach
them. On raising the body the spinal muscles are power-
fully exercised. Fig. 12 shows other modes of using the
^astic cords for strengthening the spine and chest.
FIG. 13.
28. These various appliances have been combined so as
to form a system of gymnastics suitable for parlor use;
other appliances have been added by which the muscles of
THE MUSCLES. 3?
the legs may be called into action as well as those of the
spine and upper part of the body (Fig. 13). Combinations
of cords suitable for particular cases may also be made, and
by using one or several cords on the same hook, their power
may be adapted to the strength of the most robust as well
as to that of the invalid, or of the most delicate child.
The entire apparatus is quite simple in its construction
and inexpensive, requiring but little space, and at the
same time affording a great variety of exercises.
EXERCISES THAT MAY BE PRACTISED ox THIS APPA-
RATUS.
EXERCISE I. (Fig. 18). Stand erect under the cords and place the
heels together. Grasp the handles firmly, keeping the knees and
elbows stiff, and pull downward and forward until the fingers nearly
touch the toes. Return slowly to the erect position. Repeat.
EXERCISE II. (Fig. 13). Stand erect, and having grasped the
handles overhead firmly, separate them and bring them down
slowly until they touch the sides : then return them slowly to the
original position. Repeat.
EXERCISE III. (Fig. 13). Stand erect, heels together, grasp the
handles overhead, and charge forward with the right foot. Return
to first position, and then charge with the left. Repeat, using the
right and left foot alternately.
EXERCISE IV. (Fig. 13). Stand erect, heels together. Grasp the
handle overhead, and charge forward with the right foot, knee bent.
Remain in this position and bring the arms down to the sides so that
the arm and fore-arm may form a right angle. Still holding the
handles, thrust forward, first the right hand and then the left, until
the arm is straight. Repeat. Return to first position, then charge
forward with the left foot, performing the same movements as before.
EXERCISE V. (Fig. 13). In this exercise we change to the pulleys
leading from the side posts, which can be used in several different
ways. 1st. Stand erect, heels together, facing one of the posts,
grasp the handle with the right hand, the arm being extended, then
flex the fore-arm on the arm. Repeat. Perform the same move-
ments with the left hand. 3d. Stand with back to the post ; grasp
the pulley behind with the right hand, then gradually bring the
hand forward until it is extended in a straight line in front. Repeat
Perform the same exercise with the left hand.
38 THE MUSCLES.
EXERCISE VI. (Fig. 13). This exercise is especially adapted to the
legs. Stirrups are so arranged that they can be attached to the
pulleys overhead, and can hang down to within three or four feet of
the floor. Place the foot in the stirrup, and then press down until it
touches the floor. Repeat. Exercise the left foot in the same way.
EXERCISE VII. (Fig. 13). This exercise requires a little attention
in the adjustment of the apparatus. Under the pulleys in the floor
are passed ropes which can be attached to the snap-hooks that hold
the handles overhead. Stoop forward with the knees stiff, and take
uold of the handles, and then raise the body to the erect position.
Repeat
EXERCISE VIII. (Fig. 13). Sit on the floor or on a seat three or
four inches high ; bend forward, take hold of the handles, and per-
form the same movements that you would in rowing a boat.
EXERCISE IX. (Fig. 13). The trapeze can now be let down ; take
hold of it with both hands, sustaining the weight of the body with
the arms, then rotate the body first from right to left, then from left
to right alternately. This exercise is especially suitable for females.
EXERCISE X. (Fig. 13). Grasp the trapeze as before, bearing all
the weight with the arms : then draw the body up slowly until you
can place the chin over the bars. This requires strength of muscle,
and might strain if done too violently ; if slowly performed there is
no danger.
These are but a few of the exercises that can be practised with
this apparatus. As these become familiar they can easily be modi-
fied, and new ones can be arranged to meet the requirements of
particular cases. Most of the exercises described can be practised
with one hand so as to strengthen the muscles on one side.
29. Rest. We cannot always be active: repose must
succeed labor. We obtain this rest partly by suspending
all exertion, as in sleep, and partly by a change of employ-
ment. It is said that Alfred the Great recommended that
each day should be divided in the following manner :
"Eight hours for work, eight hours for recreation, and
eight hours for sleep." This division of time is as good as
any that could now be made, if it be borne in mind that,
when the work is physical, the time of recreation should
29. Need of repose? How do we obtain rest ? Alfred the Groat ? The eight
hour division of time ?
THE MUSCLES. 39
6e devoted to the improvement of the mind; and when
mental, we should then recreate by means of physical
exercise.
30. During sleep, all voluntary activity ceases, the rapid-
ity of the circulation and breathing diminishes, and the
temperature of the body falls one or two degrees. In con-
sequence, the body needs warmer coverings than during
the hours of wakefulness. During sleep, the body seems
wholly at rest, and the mind is also inactive, if we except
those involuntary mental wanderings which we call dreams.
.Nevertheless a very active and important physical process
is going on. Nutrition, or the nourishing of the tissues,
now takes place. While the body is in action, the process
of pulling down predominates, but in sleep, that of build-
ing up takes place more actively. In this way we are re-
freshed each night, and prepared for the work and pleasures
of another day. If sleep is insufficient, the effects are seen
in the lassitude and weakness which follow. Wakefulness
is very frequently the forerunner of insanity, especially
among those who perform excessive mental labor.
31. All persons do not require the same amount of sleep,
but the average of men need from seven to nine hours.
There are well-authenticated cases where individuals have
remained without sleep for many days without apparent
injury. Frederick the Great required only five hours of
sleep daily. Bonaparte could pass days with only a few
hours of rest. But this long continued absence of sleep is
attended with danger. After loss of sleep for along period,
in some instances, stupor has come on so profoundly, that
there has been no awaking.
32. There are instances related of sailors falling asleep
30. Cessation, of voluntary activity ? Temperature of the body ? Consequence ?
Body and mind during sleep ? Nutrition ? Describe it. Consequence of insuffi-
cient sleep ?
31. Amount of sleep in different persons? Cases? Frederick the Great?
Bonaparte ? Instances of long deprivation of sleep ?
32. Instances of sailors ? French soldiers ? During torture ?
40 THE MUSCLES.
on the gun-deck of their ships while in action. On the
retreat from Moscow, the French soldiers would fall asleep
on the march, and could only be aroused by the cry, "The
Cossacks are coming !" Tortured persons are said to have
slept upon the rack in the intervals of their torture. In
early life, while engaged in a laborious country practice,
the writer not unfrequently slept soundly on horseback.
These instances, and others, show the imperative demand
which nature makes for rest in sleep.
QUESTIONS FOR TOPICAL REVIEW.
PAGE
1. What can you state of the number and division of the muscles ? 25, 26
2. Describe the structure of the muscles 25, 26
3. Their arrangement in pairs and consequent action 26
4. What is the difference between the motion called flexion and that called
extension ? 26
5. Describe their action, and state which are the more powerful 26
6. What is the difference between voluntary and involuntary muscles ? 26
7. Illustrate the difference between the two 26
8. State all you can of the tendons or sinews 27
9. What is meant by contraction of the muscles ? 27, 28
10. In how many and what ways may contraction be effected ? 28
11. What is stated of after-death contraction? 28
12. Why cannot a muscle in life continue contracted a long time ? 28
13. How then can the constant beating of the heart be explained ? 28
14. How does the strength of a man compare with that of a horse ? 29
15. What can you state in relation to the relative strength of animals ? 28, 20
16. What, in rc-lation to physical strength ? 29
17. What, in relation to physical degeneracy ? . 29. 30
18. What, in relation to the importance of exercise ? 30
19. What is the effect of exercise upon the heart, skin, and appetite ? 30, 31
20. How does exercise affect the current of the body's circulation ? 31
21. How does judicious exercise affect the muscles ? 31
22. What is stated of violent and spasmodic exercise ? 31
23. Of the exercise of walking ? 31, 32, as
24. Of running, leaping, and other modes of exercise"? 3 J
25. Of physical culture, in connection with out-door exercises ? 3.
26. Of the importance of gymnastics in our schools and colleges f 33, 34
27. Of the importance of rest from labor or exercise ? 38, 39
28. What processes take place during sleep ? *|
29. What effects follow insufficient sleep ?
]STOTES.
1. The Perfection of the Human Hand (p. 26, 1 4). "Grrdy
counts thirty-four distinct movements of the hand, and if we include the combi-
nations of these different movements, we shall reach a much higher number. Prop-
erly speaking, the hand belongs to man alone, and its form does not permit us to
consider it an organ of locomotion, as is the case with certain animals most closely
resembling man. Nothing gives a more complete idea of the perfection of the
mechanism of the hand than the execution of instrumental music. Examine ;m
artist while he plays the violin. His fingers rest upon the strings so as to leave
them exactly of the length necessary for the tones they are to give. The half of a
millimetre, more or less, greatly changes the accuracy of the note; and a chord a
millimetre out of place produces a note which even the unpractised ear can recog-
nize as false. But the fingers fall upon the strings at precisely the point required.
They run over them, succeeding each other with giddy rapidity, following every
imaginable combination, and yet the hand gliding over the instrument incessantly
changes its position. Sometimes a single finger produces an isolated note ; some-
times two or three act simultaneously to produce a concord ; while a fourth, strik-
ing a string with increasing rapidity, produces a trill which rivals the nightingale.
Add to all these the modifications necessary to swell the sound or let it die away
all, in a word, that constitutes musical expression, and it will be admitted that
this mechanism is allied to the wonderful, and that it surpasses the most per-
fect productions of human art." A further idea of the rapidity of the hand's
movements is given in the playing of a skilful pianist, whose hands, oftenest oc-
cupied together, pro 'uce on an average six to eight notes at a time, or about 640
notes in a minute in medium time, and 960 notes in extremely quick time. The
Wonders of the Human Body.
2. Health in Athletic Exercise (p. 81, 1 15). " Health is perpetual
youth that is, a state of positive health. Merely negative health, the mere keep-
ing out of the hospital for a number of years, is not health. Health is to feel the
body a luxury, as every vigorous child does; as the bird does when it shoots and
quivers through the air, not flying for the sake of the goal, but for the sake of
flight ; as the dog does when he scours madly across the meadows, or plunges
into the muddy blissfulness of the stream ; but neither bird, nor dog, nor child en-
joys his cup of physical happiness let the dull or the worldly say what they will
with a felicity so cordial as the educated palate of conscious manhood. To
' feel one's life in every limb,' this is the secret bliss of which all forms of ath-
letic exercise are merely varying disguises ; and it is absurd to say that we cannot
possess this when character is mature, but only when it is half developed. As the
flower is better than the bud, so should the fruit be better than the flower."
3. The Ill-effects of Over-exertion (p. 31, 1 17). "It should be
recollected that the action of the muscles has limits, as well as that of every other
organ of the body. The muscles and the heart may be taxed too severely, and
permanent derangements may be produced by overtaxing the human body. The
ancient gymnasts among the Greeks are said to have become prematurely old,
and the clowns (or acrobat?) and athletes of our own days suffer from the severe
strain put upon their muscular systems. 1 " The effects of boat-racing in England
have been thus described by Mr. Skey, an eminent surgeon: " The men look utter-
ly exhausted. Their white and sunken features and pallid lips show serious con-
gestion of the heart and lungs, and the air of weakness and lassitude makes it a
marvel how such great exertion should have been so nobly undergone. We bave
repeatedly seen the after ill-effects spitting of blood, congested lungs, and weak-
ness of the heart from over-distension." "Persons should neither walk, run,
NOTES.
leap, or play at any game, to the extent of producing permanent or painful exhaus-
tion. All exercise should be attended with pleasurable feelings ; and when pain is
produced by proper exercise, those who suffer should rather seek medical advice
than persevere in exercise. 1 ' Lanktster's Manual of Health.
4. Health and Strength are not always Identical (p. 34, 124).
" Health and strength are not. synonymous terms. A person may have great
strength in his limbs, or in certain muscles about the body, but really not have
good health. It is altogether a mistaken idea to suppose that physical exercises
have for their sole object the attainment of strength. There are other tissues and
organs in the human system besides the muscular ; and the healthy action of the
lungs and the stomach is far more important than great strength in the arms, legs,
or the back. It is here, in this general exercise of all the muscles and parts of the
body, that a well-regulated system of gymnastics has Its great excellence. It
aims to produce just that development of the human system upon which good
health is permanently based, described by a distinguished writer as follows :
'Health is the uniform and regular performance of all the functions of the body,
arising from the harmonious action of all its parts,' a physical condition imply-
ing that all are sound, well-fitting and well-matched. Some minds do not look
far enough into life to see this distinction, or to value it if seen; they fix their
eyes longingly upon strength upon strength now, and seemingly care not for the
power to work long, to work well, to work successfully hereafter, which is
health.' 1 '' Dr. Nathan Allen on Physical Culture.
5. Exercise should be Pleasurable (p. 33, t 22). "The world seldom
attaches much value to things which are plain and easily understood. The der-
vish in the Eastern allegory, well aware of this weakness, knew that it would be
in vain to recommend the sultan, for the cure of his disease, simply to take exer-
cise. He knew that, mankind in general required to be cheated, gulled, cajoled,
even into doing that which is to benefit themselves. He did not, therefore, tell the
eultan, who consulted him, to take exercise, but he said to him : 4 Here is a ball,
which I have stuffed with certain rare, costly, and precious medicinal herbs. And
here is a bat, the handle of which I have also stuffed with similar herbs. Your
highness must take this bat, and with it beat about this ball until you perspire
very freely. You must do this every day.' His highness did so, and in a short
time the exercise of playing at bat and ball with the dervish cured his malady."
First Help.
6. On Recreation. "Our whole method of amusements, especially for
the young, should be reformed. Gas-light should yield to daylight, night vapors
in heated and close rooms should irive way to fresh air under the open heavens,
and our young people should be brought up to work and play under the ministry
of that great solar force which is the most benign and god-like agent known to
men. Ardent spirits and tobacco should be given up, and in their stead genial
exercise of riding, gymnastics, and the dance, with music and all beautiful arts,
should be employed to stir the Mn-ruid powers and soothe the troubled affections.
The old Greeks taught music and gymnastics as parts of education, and Plato, in
urging the importance of these, still maintains that the soul is superior to the
body, and religion is the crown of all true culture. Why may not Christian peo-
ple take as broad a position on higher ground, and with a generous and genial cul-
ture- associate a faith that is no dreamy sentiment or ideal abstraction, but the
best power of man and the supreme grace of God? "7?^. T)r. Ozgood on "The
Skeleton in Modern r r ci--t ! /." >
TABLE OF THE PRINCIPAL MUSCLES.
$EE PLATE 7, PAGE 24.)
THE HEAD.
Oc-cipi-to ft'on-tti'lis 9 moves the scalp and eyebrows.
Or-bic-u-laris paipe-brae^ closes the c; *
Le-va'tor pal'pe-brae 9 opens the eye.
The Recti muscles, (4 in number) move the eye-ball.
Tempo-rat,) raige ^ Jower
IHas-seter, )
THE NECK.
o Mastoid,
Scale'ni muscles move the neck from side to side.
THE TRUNK.
moves the arm forwards.
Li-tis'si-inirs dor ni^ moves the arm backwards.
Tra-pe'zi-ns, \
Ser-ra'tns magnu*, ( move shoulder-blade.
Rhotn-boi deun, ;
In ter-costals, mo^e the ribs in respiration.
External Obliaue. )
' [ move the trunk forwards
Internal
E rector spi'nae* move the trunk
THE UPPER LIMB.
Deltoid, raises the arm
Te'res major, lowers tlie arm.
Sub-scap-u-la'ris, ) rota t e tlie arm.
Spi-nattis,
Jfi'ceps, bends forearm.
Triceps, straightens forearm.
Pro na tor, ) rotate forearm .
Sa-pinator, }
Flex' or car'pi ra-dia'lis, 1
" *>., 'j. m ove the hand.
Exten'sor car'pi ra-di-a lis*
ul-na'ris, J
More than 30 muscles take part in moving tne lingers.
THE LOWER LIMB.
ll-i'a-cus, I
Psoas magnus, I moye ^ ^ h forwards
Fec-tin-e'us,
Adduc'tor, J
Glu-te'us, } move the thigh backwards.
Pyr-iform'is, )
Sar-to'ri-us, (from Sartor, a tailor) crosses one thigh over the
other.
Rec'tus, ) moye tte leg f orwar ds.
Vas'tus, )
Biceps, I moye the leg backwards.
rac'i-lis )
Grac'i-lis,
Tibia'lis,
Gas ti'oc-ne' mi-us, \
So-le'us, J
20 muscles take part in moving the toes.
THE INTEGUMENT, OR SKIN. 41
CHAPTER III.
THE INTEGUMENT, OR SKIN.
The Integument Its Structure The Nails and Hair The Complexion
The Sebaceous Glands The Perspiratory Glands Perspiration
and its Uses Importance of Bathing Different kinds of Baths
Manner of Bathing The Benefits of the Sun Importance of Warm
Clothing Poisonous Cosmetics.
I I. The Integument. The skin is the outer covering
/ of the body. The parts directly beneath it are very sensi-
tive, and require protection. This is shown whenever by
accident the skin is broken, pierced, or torn off, the bared
surface being very tender, and painful to the touch. Nature
has provided the body with a garment that is soft, pliable,
close-fitting, and very thin, and yet sufficiently strong to
enable us to come in contact with the objects that sur-
round us, without inconvenience or suffering.
' 2. The Structure of the Skin. When examined with
the aid of the microscope, the skin is found to be made up
of two layers the outer and the inner. The inner one is
called the cutis, or true skin ; the outer one is the epider-
mis, or scarf-skin. The latter is also known as the cuticle.
These two layers are closely united, but they may be sepa-
rated from each other. This separation takes place when-
ever, from a burn, or other cause, a blister is formed;
a watery fluid is poured out between the two layers, and
lifts the epidermis from the true skin.
Of the two layers, the cuticle is the thinner in most parts
of the body, and has the appearance of a whitish mem-
brane. It is tough and elastic, is without feeling, and does
1 . What is the skin ? Parts directly beneath ? What is shown ?
2. Microscopic examination ? What is the cutis ? The cuticle ? Their union ?
How separated ? What further is said of the cuticle ?
^?x
42 THE INTEGUMENT, OR SKIN.
not bleed,when cut. Examine it more closely, and we observe
that it is composed of minute flat cells, closely compacted,
and arranged layer upon layer.
A 3. The outer layer is constantly being worn out, and
/falls from the body in the form of very fine scales. It is,
also, continually forming anew on the surface of the inner
layer. Its thickness varies in different parts of the body.
Where exposed to use, it is thick, hard, and horn-like, as
may be seen on the soles of the feet, or on the palms of the
hands, especially of those who are accustomed to perform
much manual labor. This is an admirable provision for
the increased protection of the sensitive parts below the
skin against all extraordinary exposure. Even the liabil-
ities of these parts to injury, are thus kindly provided for
by "the Hand that made us." (Read Note 10, end of Chapter.)
4. The cutis, or true skin, lies beneath the epidermis,
and is its origin and support. It is firm, dense, elastic,
very sensitive, and is freely supplied with blood-vessels.
It is closely connected with the tissues below it, but may
be separated by means of a sharp instrument. The surface
of the cutis is not smooth, but is covered here and there
with minute elevations, called papillm. These are arranged
in rows, along fine lines, or ridges, such as those which
mark the palm and fingers ; their number is about 80 to
the square line (a line being one-twelfth of an inch).
These papillm contain the blood-vessels which carry the
supply of blood needed by the ever-wasting skin. They
contain nerves also, and are largely concerned in the
sense of touch; hence they are particularly abundant
where the touch is most delicate, as at the ends of the
^ fingers.
5. The Nails and Hair, These are appendages of the
3. Wearing out of the cuticle ? What then ? Variety in thickness of cuticle r
How accounted for?
4. Location and office of the cutis? What further is said of it? Papillae?
Touch ?
5. What are the nails and hair ? The growth of the nail ? The rapidity of its
growth ? Accident to the nail ?
THE INTEGUMENT, OR SKIN.
43
skin, and although very unlike the cuticle as it appears on
the surface of the body, they are, in reality, modified forms
of that layer of the skin. The nail grows from a fold of
the cuticle at the root, and from the under surface. As
fast as it is formed, it is
constantly being pushed
outward. The rapidity of
its growth can be ascer-
tained by filing a slight
groove on its surface, and
noticing how the space be-
tween it and the root of
the nail increases, in the
course of a few weeks.
When the nail is removed
by any accident, it will be
replaced by a new one, if
the root be not injured. *
/* 6. The hairs are pro-
x duced in a similar manner;
Fig. 14.
a, b. THE ROOT OF A HAIR.
the Skin forming depres- j, 2 , 3. The skin forming the hair sac. 4. Se.
Sions, Or hair SaCS, * baceous glands. The hair sac.
c. TRANSVERSE SECTION OF A HAIR.
hair sacs, from
the bottom of which they
grow and are nourished (Fig. 14). They are found, ot
greater or less length, on almost all parts of the surface,
except the palms of the hands and soles of the feet. On
certain parts of the body, they grow to great length ; on
other parts they are so short, that they do not rise beyond
the hair sac in which they originate.
7. The bulb, or root, from which the hair arises, is
lodged in a small pouch, or depression in the skin. The
shaft is the part which grows out beyond the level of the
skin. Its growth is altogether in one direction, in length
alone. The outer part of the hair is quite firm, while its
6. How are the hairs produced ? Difference in their length ?
7. Root of the hair Shaft ? Firmness and softness of the hair?
(* Read Note n, end of Chapter.)
44 THE INTEGUMENT, OR SKIN.
interior is softer, and probably conveys the fluids by which
it is nourished. The hair is more glossy in health than at
other times.
A 8. The nail serves as a protection to the end of the
f finger, and also enables us to grasp more firmly, and to
pick up small objects. The hair, too, is a protection to
the parts it covers. On the head, it shields the brain from
extremes of heat and cold, and moderates the force of blows
upon the scalp. On the body, it is useful in affording a
more extensive surface for carrying off the perspiration.
9. Complexion. In the deeper cells of the cuticle
lies a pigment, or coloring matter, consisting of minute
colored grains. On this pigment complexion depends; and,
according as it is present in less or greater amount, occa-
sions the difference of hue, that exists between the light
and dark races of men, and between the blonde and bru-
nette of the white races. Freckles are due to an irregular
increase of coloring matter.
A 10. The sun has a powerful influence over the develop-
/ ment of this pigment, as is shown by the swarthy hue of
those of the white race who have colonized in tropical
climates. It is also well illustrated by the fact, that
among the Jews who have settled in northern Europe,
there are many who are fair complexioned, while those
residing in India, are as dark as the Hindoos around them.
f* 11. An Albino is a person who may be said to have no
complexion; that is, there is an entire absence of coloring
matter from the skin, hair, and iris of the eye. This con-
dition more frequently occurs among the dark races, and
in hot climates, although it has been observed in almost
every race and clime.
12. Sebaceous Glands. There are in the skin certain
8. Office of the nail? Of the hair? Give the illustrations.
9. On what does the complexion depend? Light and dark races ? Freckles?
10. Influence of the sun ? How illustrated? Jews?
11. What is an Albino ? Where are Albinos found ?
12. What are sebaceous glands ? How do they act ? Sebaceous glands of the
* How do they act ?
THE INTEGUMENT, OR SKIN. 45
small glands, which produce an oily substance, called se-
baceous matter. These glands are little rounded sacs,
usually connected with the hair-bulbs; and upon these
bulbs, they empty their product of oil, which acts as a
natural and adequate dressing for the hair (4, Fig. 13). A
portion of the sebaceous matter passes out upon the sur-
face, and prevents the cuticle from becoming dry and hard.
The glands situated upon the face and forehead, open
directly upon the skin. In these, the sebaceous matter is
liable to collect, and become too hard to flow off naturally.
13. These glands on the face and forehead frequently
appear, on the faces of the young, as small black points,
which are incorrectly called "worms." It is true, that oc-
casionally living animalcules are found in this thickened
sebaceous matter, but they can only be detected by the aid
of the microscope. This sebaceous matter acts not only to
keep the skin flexible, and furnish for the hair an oily
dressing, but it especially serves to protect the skin and
hair, from the acridity arising from the perspiration.
i 14. The Perspiratory Glands. The chief product
of the skin's action is the perspiration. For the forma-
tion of this, there are furnished countless numbers of
little sweat-glands in the true skin. They consist of fine
tubes, with globe-like coils at their deeper extremity. Their
mouths or openings may be seen with an ordinary magnifying
glass, upon the fine ridges which mark the fingers. These
tubes, if uncoiled, measure about one-tenth of an inch in
length. In diameter, they are about one three-hundredth
of an inch, and upon certain parts of the body there are not
far from three thousand of these glands to the square inch.
Their whole number in the body is, therefore, very great;
and, in fact, it is computed if they were all united, end to end.
their combined measurement would exceed three miles.
1 3 , Black points, called worms ? Animalcules ? Service performed by seba-
ceous matter?
14. Perspiration? Sweat glands? Of what do they consist ? Dimension of
the tubes?
46 THE INTEGUMENT, OR SKIN,
/* 15. The Sensible and Insensible Perspiration.
The pores of the skin are constantly exhaling a watery
fluid; but, under ordinary circumstances, there is no
moisture apparent upon the surface, for it evaporates as
rapidly as it is formed. This is called insensible perspira-
tion. Under the influence of heat or exercise, however,
this fluid is excreted more abundantly, and appears on the
surface in the form of minute, colorless drops. It is then
termed sensible perspiration.
, 16. Water is the chief component of this fluid, there
being about ninety-eight parts of water to two parts of
solid matter. The quantity escaping from the body varies
greatly, according to the temperature of the air, the
occupation of the individual, and other circumstances.
The average daily amount of this excretion, in the adult,
is not far from thirty ounces, nearly two pints, or more
tfian nine grains each minute.
N 17. The Uses of the Perspiration. Besides liber-
ating from the blood this large amount of water, with the
effete matter it contains, the perspiration serves to regulate
the temperature of the body. That is to say, as evapora-
tion always diminishes temperature, so the perspiration, as
it passes off in the form of fine vapor, cools the surface.
Accordingly, in hot weather this function is much more
active, and the cooling influence increases in proportion.
When the air is already charged with moisture, and does
not readily receive this vapor of the body, the heat of
the atmosphere apparently increases, and the discomfort
therefrom is relatively greater.
N 18. The importance of this excretion is shown by the
effects that often follow its temporary interruption, namely,
headache, fever, and the other symptoms that accompany
1 5. What is sensible perspiration ? Insensible perspiration ?
16. Components of perspiration? Upon what does perspiration depend?
Amount of perspiration daily ?
1 7. What does perspiration set free from the blood ? What other service doe;s
perspiration perform? Explain the process.
18. Effect of interruption of excretion ? What experiments are mentioned. ?
THE INTEGUMENT, OR SKIN. 47
" taking cold."' When the perspiration is completely
checked, the consequences are very serious. Experiments
have been performed upon certain smaller animals, as rab-
bits, to ascertain the results of closing the perspiratory
tubes. When they are covered by a coating of varnish
impervious to water and gases, death ensues in from six to
twelve hours ; the attendant symptoms resembling those
Of Suffocation. (Read Note I, end of Chapter)
A 19. It is related that, at the coronation of one of the
Popes about three hundred years ago, a little boy was
chosen to act the part of an angel : and in order that his
appearance might be as gorgeous as possible, he was cov-
ered from head to foot with a coating of gold foil. He was
soon taken sick, and although every known means were
employed for his recovery, except the removal of his fatal
golden covering, he died in a few hours.
20. The Importance of Bathing. From these con-
siderations, it is evident that health must greatly depend
upon the free action of the skin. " He who keeps the skin
ruddy and soft, shuts many gates against disease." When
the watery portion of the perspiration evaporates, the solid
matter is left behind on the surface. There, also, remain
the scales of the worn-out cuticle, and the excess of seba-
ceous matter. In order to secure the natural action of the
skin, these impurities require to be removed by the frequent
application of Water. (Read Note 8, end of Chapter.}
21. Iii warm climates, and during hot weather, ablution
' should be more frequently practised. For a person in
good health, a daily cold bath is advisable. To this should
be added occasionally a tepid bath, with soap, water alone
not being sufficient to remove impurities of a greasy nature.
Soap facilitates this, by forming with such substances a
chemical mixture, which is readily soluble in water, and is
by it removed from the body. (Read Note 7, end of Chapter.}
19. Give the story in relation to the boy covered with gold foil.
2O Give the quotation. Perspiration ?
2 1 . Ablution in warm climate's ? What advice is grivea ?
48 THE INTEGUMENT, OR SKIN.
/
A 22. There is a maxim by the chemist Liebig, to the effect^
' that the civilization of a nation is high, in proportion to
the amount of soap that it consumes ; and that it is low, in
proportion to its use of perfumes. In some degree, we may
apply the same test to the refinement of an individual.
The soap removes impurity; the perfume covers, while
retaining it. (Read Notes 6 and 12, end of Chapter^
. The different kinds of Baths. All persons are
not alike able to use the cold bath. When the health is
vigorous, and the system does not feel a shock after such a
bath, a prompt reaction and glow upon the surface will
show that it is beneficial. \Yhere this pleasurable feeling
is not experienced, but rather a chill and sense of depres-
sion ensues, we are warned that the system will not,
with impunity, endure cold bathing.
24. It should also be borne in mind, that the warm or hot
bath cannot be continued so long, or repeated so frequently
as the cold, on account of the enervating effect of unusual
heat so applied to the body. For persons who are not in
robust health, one warm bath each week is sufficient ; this
class should be careful to avoid every extreme in reference
to bathing, clothing, and whatever greatly affects the actiou
of the skin.
25. Sea-bathing is even more invigorating than fresh -
water bathing. Those who cannot endure the fresh water,
are often benefited by the salt-water baths. This may be
accounted for, in part, by the stimulant action upon the
surface, of the saline particles of the sea-water; but the
exciting scenes and circumstances of sea-bathing also exert
an important influence. The open-air exercise, the rolling
surf, the genial weather, and usually the cheerful company,
add to its intrinsic benefits. (Read Note 2.)
22. LiebigV maxim ? What, further it* added ?
23. What is said about cold bathing ?
24. What is said about warm bathing ?
25. What is said about sea-bathing?
.
/
THE INTEGUMENT, OR SKIN. 49
26. Time and Manner of Bathing. A person in
sound health may take a bath at almost any time, except
directly after a full meal. The most appropriate time is
about three hours after a meal, the noon-hour being proba-
bly the best. For the cold bath, taken rapidly, no time is
better than immediately after rising. Those beginning the
use of cold baths should first try them at 70 Fahr., and
gradually use those of a lower temperature. From five to
twenty minutes may be considered the proper limit of time
to remain in a bath ; but a sensation of chilliness is a signal
to withdraw instantly, whether at home, or at the sea-side
Two sea-baths may be taken daily ; one of any other kind
is sufficient.
27. The body should be warm, rather than cold, when
stepping into the bath; and after it, the skin should be
thoroughly dried with a coarse towel. It is best to continue
friction until there is a sensation of warmth or "glow"
throughout the entire surface. This reaction is the test
of the good effects of the bath. If reaction is still incom-
plete, a short walk may be taken, especially in the sunshine.
It is very congenial, however, both to health and comfort,
to rest for a short time directly after bathing, or to take
some light refreshment. This is better than severe exer-
cise or a full meal.
A 28. Bathing among the Ancients. The Romans
and other nations of antiquity made great use of the
vapor-bath as a means of preserving the health, but more
particularly as a luxury. Their method was not unlike
that employed in northern Europe, at the present day.
The public baths of Rome and other cities are among the
grandest and most interesting monuments of ancient
luxury and splendor; and from their ruins have been re-
covered some of the most beautiful works of art.
26. What is said as to the time and manner of bathing ?
27. Condition of the body when bathing? Direction, after bathing?
28. Bathing among the ancients? Baths of Rome?
60 THE INTEGUMENT, OR SKIN.
K 29. The Thermae, as the baths of Eome were called;
* were of great extent, built very substantially, and orna^
mented at vast expense. They were practically free to all,
the cost of a bath having been less than a cent, It is
related that some persons bathed seven times a day. After
the bath their bodies were anointed with perfumed oil. If
the weather was fine, they passed directly from the Thermae
into the gymnasium, and engaged in some gentle exercise
previous to taking the midday meal. Between two r"d
three in the afternoon was the favorite hour for this ancient
luxury. Swimming was a favorite exercise, and a knowl-
edge of it was regarded as necessary to every educated man.
Their common expression, when speaking of an ignorant
person, was, " He can neither read nor swim."
X 30. The Sun-Bath. Some also were accustomed daily
to anoint themselves, and lie or walk in apartments ar-
ranged for the purpose, with naked bodies exposed to the
direct rays of the sun. There is an interesting allusion to
this practice, in a letter of the younger Pliny to the his-
torian Tacitus, describing the destruction of Pompeii by
an eruption of Vesuvius. " My uncle," (Pliny the elder,)
"was at that time in command of the fleet at Misenum.
On the 24th of August, about one in the afternoon, my
mother desired him to notice a cloud which seemed of un-
usual shape and dimensions. He had just returned from
talcing the benefit of the sun, and after a cold bath, and a
slight repast, had retired to his study." Then follows a
description of the destruction of Pompeii, and the death
of the elder Pliny.
A 31. We may judge somewhat of " the benefits of the
sun," by observing the unnatural and undeveloped condi-
tion of plants and animals which are deprived of light.
Plants become blanched and tender ; the fish of subterra-
29. After tvi bath ? Swimming among the ancients ?
30. The Sun-bath ? The story of Pliny ?
3 1 . Benefit of the sun ? Effect upon plants ? Skin f
THE INTEGUMENT, OR SKIN. 51
r,
nean lakes, where no light enters, are undersized, and have
no eyes; tadpoles kept in the dark do not develop into
frogs; men growing up in mines are sallow, pale, and
deformed. Besides the well-known effect of solar light in
tanning the skin, it also makes it thicker and better able
to resist exposure; though the complexion may be thereby
injured, the health gains more than compensates for the
loss of beauty. " To make good the loss of the lily, where
the sun has cast his ray, he seldom fails to plant the rose." *
32. Clothing. In reference to clothing, we are far
more apt, in our changeful climate, to use too little than
too much. An aphorism of Boerhaave, worth remember-
ing, if not of adopting, is, "We should put off our winter
clothing 011 midsummer's day, and put it on again the day
after." He also says, " Only fools and beggars suffer from
the cold ; the latter not being able to get sufficient clothes,
the others not having the sense to wear them." The prac-
tice of exposing the limbs and necks of young children,
for the alleged purpose of "hardening" them, is quite
hazardous. It is not to be denied that some seem to be
made tough by the process ; but it is so only with the rugged
children, the delicate ones will invariably suffer under this
fanciful treatment. As has been stated before, the skin is
constantly acting, by night as well as by day. It is there-
fore conducive both to cleanliness and comfort to change
entirely the clothing on retiring for the night. The day-
clothing should be aired during the night, and the bedding
should be aired in the morning, for the same reason, f
33. Poisonous Cosmetics. The extensive use of
wsmetics for the complexion is a fertile source of disease.
The majority of these preparations contain certain poison-
ous mineral substances, chiefly lead. Now, the skin
rapidly absorbs the fine particles of lead, and the system
32. Direction about clothing? Exposing limbs of children? Clothing, night
and day ?
33. Cosmetics ? Painters' colic ?
C* Read Notes 3 and 4, end of Chapter.}
(t Read ffotes 5 and 9, end of CJiapter.}
52 THE INTEGUMENT, OR SKIN.
experiences the same evil effects that are observed among
the operatives in lead works and painters, namely, "paint-
ers' colic," and paralysis of the hands, called "wrist-drop."
r34. Certain hair-dyes also contain lead, together with
other noxious and filthy ing 7 edients. These do not work
as great harm as the cosn? ;tics, since they are purposely
kept away from the skir, but they rob the hair of its
vitality. Eye-washes, too, are made from solutions of lead,
and many an eye has been ruined by their use. They de-
posit a white metallic scale on the surface of the eye, which
becomes a permanent obstruction to the vision.
QUESTIONS FO.^ TOPICAL REVIEW.
PAGE
1. What are the characteristics of the skin, and what office does it perform ? 41
2. What can you state of the structure of the skin ? 41
3. Describe the cuticle and tell its use 41,42
4. Describe the cutis or true skin and tell its use 42
5. What can you state of the nature and growth of the nail ? . . 42, 43
6. Of the nature and growth of the hair ? 42, 43, 44
7. Of the offices performed by the nails and hair ? 44
8. How is the difference in complexion in different persons accounted for ?. 44
9. How is the presence of freckles accounted for ? 44
10. How does Nature provide a dressing for the hair ? 44, 45
11. What other service do the sebaceous glands perform ? 45
12. State what you can of the perspiratory glands 45
18. What is the difference between sensible and insensible perspiration?.. . 46
14. State, the uses and importance of perspiration 46, 47
15. WhaMmpurities gather naturally on the skin ? 47
16. Repeat what is said of the importance of bathing 47, 48
17. When should we indulge in cold, warm, and sea bathing ? 48, 49
18. What is the effect in each case ? 48
19. What directions are given as to the time and manner for bathing ? 49
20. What is related of bathing among the ancients ? 49, 50
21. What, is related to show the antiquity of sun-bathing ? 50
22. What are the effects of sun bathing? 50,51
23. What directions arc given in relation to clothing the body ? 51
24. What can you state of poisonous cosmetics ? 51, 52
25. Of hair-dyes and eye-washes? 52
NOTES.
1. On taking Cold (p. 47, 1 18). "Of all the things to which humanity Is
liable, there is none which recurs more frequently, and whose consequences are
more troublesome and often dangerous, than ' taking cold.'' Some persons have quite
a faculty for taking cold, while others do so but rarely. And yet the one does not
argue delicacy of constitutition, or the other strength. The body of man has a
constant and agreeable temperature in health, the variation being slight. In fact
any great variation is incompatible with health, and constitutes disease. Clothes,
by preventing the radiation away of heat from the surface, retain it, and so the feel-
ing of cold is not so great, that is, the surface does not become so cold. Clothes
are non-conductors of heat when dry, but let them be saturated with water, and un-
less the loss of heat be met by increased production, there is a lowering of the body
temperature ' taking cold.' Thus, if exertion be continued, and more heat is pro-
duced to meet the loss until a change of dry clothing is procurable, no injury results.
But let the wet clothes be worn without a corresponding heat production, as when,
children sit down in school in their wet clothes, or the shop-bay stands in his moist
garments ; then there is a rapid loss of heat, a lowering of body temperature, and
a cold is ' caught.' So is a cold caught by wet feet, when the heat is radiated
away from the feet ; if exercise be continued the cold is not experienced. A
damp bed gives cold because the moist beclclother conduct away the heat, and the
body temperature is lowered.'" Fotherglli on the Maintenance of Health.
2. The Proper Use of Sea-bathing (p. 48, 1 25)." The length of
time during which a person should remain in the water necessarily varies accord-
ing to the age, sex, and constitutional strength of the bather. Due regard should
also be had to the state of the weather and season of the year.
" In the case of children, five, gradually extended to ten minutes; of women, ten
to fifteen minutes; and of men, a quarter of an hour or more, is a fair average
period. There are some prople, doubtless, to whom these periods will appear insuf-
ficient, and who insist on remaining so long in the water that their skin becomes
cold and blue, their teeth begin to chatter, and a condition of general exhaustion
comes on ; people, in short, who have the ' most ' for their money, like the country-
man who grumbled at having been conveyed thirty mile? in about half-an-hour by
an express train, on the score that the length of time occupied in the journey wat
not proportionate to the fare that he had paid. On entering the water, the bather
should immerse the whole of the body two or three times, so as to get the action of
the shock from the cold water distributed over its entire surface. There should bo
no hesitancy, no dabbling about with the feet, but a good plunge at once into the
next wave that washes in. Upon coming out of the water the bather should dry the
body with good rough towels, dress quickly and take a brisk walk for a short
distance. If there be any feeling of exhaustion or nervous depression, a little
food or drink should be taken." Abbotts Smith or. Sea-bathing.
3. Light Influences Growth and Health (p. 51, ^ 31).- "I have
several times taken two potatoes which were as nearly as possible alike, and placed
one under a bell-glass through which the light could pass, and the other under a
similar cover rendered opaque by several coats of black paint. Sprouting went
on unchecked under the translucent glass, while it was always notably retarded
and sometimes prevented in the potato under the dark glass. Milne Edwards, a
distinguished Frejich physiologist, performed a series of experiments which
showed that tadpoles when deprived of light did not develop into the frog. I have
several times repeated his experiments, and always with confirmatory results. On
NOTES.
one occasion I prevented for one hundred and twenty-five days the development
of a tadpole, by confining it in a vessel to which the ray? of light had no access.
On placing it in a receptacle open to the light, the process of transformation
was at once begun, and was completed in fifteen days. The practical application
of these and similar observations is this, that care should be taken both in health
and disease to ensure a sufficient amount of sunlight to the inmates of houses,
and that it is impossible to rear well-formed, strong, and robust children unless at-
tention is paid to this requirement." Hammond on the Influence of Light.
4. Light ill tlie Sick-room (p. 51, t 31). "It is the unqualified result of
all my experience with the sick, that second only to their need of fresh air is
their need of light; that, after a close room, what hurts them most is a dark
room, and that it is not only light, but direct sunlight they want. You had better
carry your patient about after the sun, according to the aspect of the rooms, if
circumstances permit, than let him linger in a room when the fun is off. People
think that the effect is upon the spirits only. This is by no means the case. Who
has not observed the purifying effect of light, and especially of direct sunlight,
upon the air of a room 1 Here is an observation within everybody's experience.
Go into a room where the shutters are always shut (in a sick-room or a bedroom
there should never be shutters shut), and though the room be uninhabited,
though the air has never been polluted by the breathing of human beings,
you will observe a close, musty smell of corrupt air of air, unpurified
by the effect of the Fun's rays. The mustiness of dark rooms and corners,
indeed, is proverbial. The cheerfulness of a room, the usefulness of light
in treating disease, is all-important. It is a curious thing to observe how almost
all patients lie with their faces turned to the light, exactly as plants always
make their way towards the light." Florence Nightingale* s Notes on Nursing.
5. Under-clotliiiig and Bedding (p. 51, ^ 32). All clothing worn
during the day should be removed at night. A practice prevails in tropical
countries of shaking thoroughly every article of apparel just before it is placed on
the body. The motive which prompts this comes from the fear lest a centipede or
other lively and virulent specimen of natural history has hid itself somewhere within
the folds of the garment. Even without the danger of wearing one's shirt in con-
junction with such an intruder, it is an excellent practice to shake it and every
other article of clothing thoroughly before putting them on. The garments worn
next to the skin should be changed before they become saturated with the secretions
of the sebaceous glands. This can be accomplished by renewing them twice a
week, though the majority of people only change them once in that period. Combe
recommends to wear two sets of flannels, each being worn and aired by turns, on
alternate days ; he likewise praises a practice common in Italy; namely, instead
of beds being made up in the morning the moment they are vacated, and whilo
still saturated with the nocturnal exhalations, the bed-clothes are thrown over
the backs of chairs, the mattresses shaken up, and the window thrown open for
the greater part of the day. This practice, so consonant with reason, imparts a
freshness which is peculiarly grateful and conducive to sleep. Florence
Nightingale, who never fails to speak plainly, says: " Feverishness is generally sup-
P'>ppd to be a symptom of fever; in nine capes out of ten it is a symptom oJ
bedding. A real patient should have two beds?, remaining only twelve houj
in each; on no account to carry his sheets with him." Draper (in part}.
NOTES.
6. Care of the Skin and Nails (p. 48, 1 22). Much ignorance prevails
amongst the public as to the use of soap and water. Those who have very sensi-
tive skins should use soft water, for the face at all events, and the best water, if it
can be had, is rain-water with the cold taken off it. Nor is it every kind of soap
which is tolerated by such persons ; probably the safest soaps are, not those which
are said to contain, but those which really do contain, a large portion of glycerine.
The culture of the nails, which when perfect constitute so great a beauty, is of
much importance ; but the tendency is to injure them by too much attention.
The scissors should never be used, except to pare the free edges when they have
become ragged or too long, and the folds of scarf skin which overlap the roots
should not, as a rule, be touched. The upper surfaces of the nails should on no
account be touched with the knife, as it is so often done, the nail brush being
amply sufficient to keep them clean, without imparing their smooth and polished
surfaces. People's Magazine.
7- An Imaginary Conversation on Baths and Bathing (p. 47,! 21).
" I have often amused myself, by fancying one question which an old Roman
emperor would ask, were he to rise from his grave and visit the sights of London
under the guidance of some minister of state. The august shade would, doubt-
less, admire our railroads and bridges, our cathedrals and our public parks, and
much more of which we need not be ashamed. But after a while, I think, he
would look round, whether in London or in most of our great cities, inquiringly
and in vain, for one class of buildings, which in his empire were wont to be most
conspicuous and splendid. 'And where,' he would ask, ' are your public baths? '
And if the minister of state who was his guide shonld answer' O great Caesar, I
really do not know. I believe there are some somewhere in some out-of-the-way
place ; and I think there have been some meetings lately, and an amateur concert,
for restoring, by private subscriptions, some baths and wash-houses which had
fallen to decay. And there may be two or three more about the metropolis ; for
parishes have power to establish such places, if they think fit, and choose to pay for
them out of the rates : 'Then, I think, the august shade might well make answer
' We used to call you, in old Rome, northern barbarians. It seems that you have not
lost all your barbarian habits. Are you aware that, in every city in the Roman
empire, there were, as a matter of course, public baths open, not only to the poorest
freeman, but to the slave, usually for the payment of the smallest current coin, and
often gratuitously? Are you aware that in Rome itself, millionaire after million-
aire, emperor after emperor, built baths, and yet more baths ; and connected with
them gymnasia for exercise, libraries, and porticos, wherein the people might have
shade and shelter, and rest ? Are you aware that these baths were of the most
magnificent architecture, decorated with marbles, paintings, sculptures, fountains,
what not? And yet I had heard, in Hades down below, that you prided your-
selves here on the study of the learned languages.' " Rev. Charles Kingsley on
the A ir-mothers. ^
8. Bathing (p. 47, T 20). "When the civilization of Egypt, Greece, and
Rome faded, the world passed through dark ages of mental and physical bar-
barism. For a thousand years there was not a man or woman in Europe that
ever took a bath, if the historian of those times, Michelet, is to be believed. No
wonder that there came the wondrous epidemics of the middle ages, which cut
off one-fourth of the population of Europe the spotted plague, the black death,
sweating sickness, and the terrible mental epidemics which followed in their
train the dancing mania, the mewing mania, and the biting mania. Not only
their persons, but their houses were uncleanly, even in the classes that were well-
to-do. Filth, instead of being abhorred, was almost sanctified." Lyon Play fair.
9. Rules as to Clothing (p. 51, 1 32). -Protection against Cold.Yor
equal thicknesses, wool is much superior to either cotton or linen, and should be
NOTES.
worn for all under clothing. In case of extreme cold, besides wool, leather or
water-proof clothing is useful. Cotton and linen are nearly equal.
Protection against Heat. Texture has nothing to do with protection from the
direct solar rays ; this depends entirely on color. White is the best color; then
gray, yellow, pink, blue, black. In hot countries therefore, white or light-gray
clothing should be chosen. In the shade the effect of color is not marked. The
thickness and the conducting power of the material are the conditions (especially
the former) which influence heat.
The body should not only be so protected by its covering as to be kept from
rain and damp ; but the clothing must be so ventilated that the emanations from
the skin shall not accumulate. The wearing of the unventilated beaver hat, or fur
cap, is a ready method of suppressing the natural growth of the hair, and of caus-
ing the retention of that effete eplLl-elial scale commonly called scurf, or dandruff.
The wearing of tightly-fitting water -proof coats cannot be habitually practiced
without danger to the wearer ; the very painful and troublesome ailment, rheuma-
tism, has in many persons been produced by this manner of locking in the excre-
tions of the surface. Dr. B. \V. Richardson.
1 0. The Renewal of the Cuticle (p. 42, f 3). The skin is not a permanent
sheath, but is, as it were, always wearing out and rubbing off, and new skin is
always rising up from underneath. A snake leaves off his whole skin at once, as
we leave off a suit of clothes or a dress, and sometimes we may find his whole
cast-off covering turned inside out, just as he crept out of it. In man, generally
we do not notice the dead particles of the skin as it wears off, but where the cuticle
is pretty thick, as on the soles of the feet, we can see it peel off in little rolls
whenever we wash the feet in hot water. After scarlet fever, too, sometimes
the dead skin comes off in great flakes, and from the hands almost like the fingers
of a glove. Berners.
11. The Life of the Cells of the Body (p. 43, t 5). "The life of the
body is long under fortunate circumstances ; that of our cells is short. We all
know that the surface of the body is covered by layers of cells. The superficial
layers are in loose connection ; they are cells in old age. The friction of our
clothing daily removes an immense number of them. A cleanly person who uses
sponge and towel energetically every day rubs off a still greater quantity.
" This takes place very actively in one month. We swallow ; our tongue acts
in speaking; drink and food pass this way. Now, the mucous membrane of the
mouth is covered with layers of cells. Here, also, many thousand senile cells are
rubbed off daily. And so on through the entire digestive tract. An immense
number of cells, these living corner-stones of the body, is thus lost daily.
" To show the duration of life in one kind of cell, let us turn to the human nail.
The latter, growing from a furrow of the skin, is made up of skin-cells. In the
depth of the furrow, youth prevails ; at the upper margin which we trim old
age. Berthold proved that a nail-cell lives four months in ^frnmer and five in
winter. A person dying in his Both year, has changed his nail 200 times, at least
and the nail appeared such an inanimate, unvarying thing ! No other cells, AVC
believe, have a life nearly so long as that of the nail." Compendium of Histology
by Heinrich Frey.
12. On Scents (p. 48, [ 22)." They are the only resource of rude and dirty
times against offensive emanations from decaying animal and vegetable sub-
stances, from undrained and untidy dwellings, from unclean clothes, from ill-
washed skins, and from ill-used stomachs. The scented handkerchief, in these
circumstances, takes the place of the spoc ge and the bath ; the pastile hides the
want of ventilation ; the otto of roses seems to render the scavenger unnecessary ;
and a sprinkling of musk sets all other smells and stinks at defiance." Johnston.
THE CHEMISTRY OF FOOD. 53
CHAPTER IV.
THE CHEMISTRY OF FOOD.
The Source of Food Inorganic Substances Water Salt Lime Iron
Organic Substances Albumen, Fibrin, and Casein The Fats or
Oils The Sugars, Starch, and Gum Stimulating Substances
Necessity of a Regulated Diet.
/* 1. The Source of Food. The term food includes all
I those substances, whether liquid or solid, which are neces-
~ary for the nourishment of the body. The original source
of all food is the earth, which the poet has fitly styled the
" Mother of all living." In her bosom, and in the atmos-
phere about her, are contained all the elements on which
life depends. But man is unable to obtain nourishment
directly from such crude chemical forms as he finds in the
inorganic world. They must, with a few exceptions, be
prepared for his use, by being transformed into new and
higher combinations, more closely resembling the tissues
of his own body.
r2. This transformation is effected, first, by the vegetable
world. But all plants are not alike useful to man ; while
some are absolutely hurtful. Accordingly, he must learn
to discriminate between that which is poisonous and that
which is lirttupporting. Again, all parts of the same
plant or tree are not alike beneficial: in some, the fruit,
in others, the leaves, and in others, the seeds only are
sufficiently refined for his use. These he must learn
to select ; he must also learn the proper modes of prepar'
ing each kind for his table, whether by cooking or othef
processes. (Read Note 6, end of Chapter)
1 . The term food ? Source of food ? Need of preparing food ?
2. Usefulness and hurtfulawM of plants ? Wht then must man do 1 Part* ot
the same plant or tree ?
54 THE CHEMISTRY OF FOOD.
3. Again, certain forms of the vegetable creation which
are unfit, in their crude state, for man's food, and which he
rejects, are chosen as food by some of the lower animals,
and are, by them, made ready for his use. Thus the bee
takes the clover, that man cannot eat, and from it collects
honey. The cattle eat the husks of corn and the dried
grass, that are by far too coarse for man, and in their own
flesh convert them into tissues closely resembling his mus-
cular tissue. In this way, by the aid of the transforming
processes of the vegetable and animal creations, the simple
chemical elements of the mineral kingdom are elaborated
into Our choice articles of food. (Read Note 13, end of Chapter^
r4. Inorganic Substances. The substances we use as
food are classified as organic and inorganic. By organic
substances are meant those derived from living forms, such
as vegetables and animals. Inorganic substances are those
simpler inanimate forms which belong to the mineral
kingdom. The former alone are commonly spoken of as
food, but the latter enter very largely into the constitution
of the body, and must therefore be present in our food.
With the exception of two articles, water and common
salt, these substances only enter the system when blended
with organic substances.
r 5. Water. Water, from a physiological point of view, is
the most important of all the articles of food. It is every-
where found in the body, even in the bones and the teeth-
It has been computed that as large a proportion as two"
thirds of the body is water. The teeth, thedensest of the
solids in the human system, contain ten per cent, of water.
The muscles, tendons, and ligaments are more than half
water; for it is found that they lose more than half their
3. Certain forms of vegetable creation? Example of the bee? Cattle? The
inference ?
4. What classification ? Define organic substances. Inorganic. Organic,
how spoken of? The inorganic ? Water and salt ?
5. Water in physiology ? Where found ? Computation? Water in the teeth*
Muscles, tendons, and ligaments ? ITmv ascertained ? Water in the fluids of th-*
body ? What is the advantage ~;
THE CHEMISTRY OF FOOD. 55
weight when dried with moderate heat. But it is in the
-fluids of tho body that water is found most abundantly.
It gives to them the power of holding a great variety of
substances in solution, and is the great highway by which
new supplies are conveyed to the point where they are
required, and by which old particles of matter, that have
served their uses, are brought to the outlets of the body to
be thus removed from the system. (Read Notes i and 7.)
6. Man can remain a longer time without solid food
than without water. He may be deprived of the former
for ten to twelve hours without great suffering, but depri-
vation of water for the same length of time will produce
both severe pain and great weakness. The food should contain
not less than two parts of water to one of solid nutriment.
Water constitutes the great bulk of all our drinks, and is
also a large constituent of the meats, vegetables, and fruits
which come upon the table. Fruits, especially, contain it
in great abundance, and, in their proper season, furnish
most agreeable and refreshing supplies of the needed fluid.
7. Common Salt. Salt, or sodium chloride, as an
article of food, is obtained chiefly from the mineral king-
dom: although plants contain it in small quantities, and
it is also found in the tissues of nearly all animals used
as food. In the human body, it is an ingredient of all
the solids and fluids. The importance of salt to animal
life in general, is shown by the great appetite for it mani-
fested by domestic animals, and also by the habitual resort
of herds of -Cold beasts to the " salt-licks" or springs. In
those parts of the world where salt is obtained with diffi-
culty, man places a very high price upon it.
F 8. Experiments upon domestic animals show that the
withdrawal of salt from their food, not only makes their
6. Length of time man can do without food or water ? Give the comparison?
Rulk of drinks ? Constituent of meats, etc. ? Fruite ?
7. Salt, how obtained ? Where found? In the human body? Importance ol
a t ''. What else can you et.atp of the value of talt ?
8. Experiments npon animals?
53 THE CHEMISTRY OF FOOD.
r.
r
hides rough and causes the hair to fall out, but also inter-
feres with the proper digestion of food. If it be withheld
persistently, they become entirely unable to appropriate
nourishment, and die of starvation. (Read Note 2.)
9. Salt is usually taken into the -system in sufficient
quantities in our food. Even the water we drink often
has traces of it. The habitual use of much salt in cook-
ing, or as a seasoning at the table, is not wise; and while
it may not lead to consumption, as some writers declare, it
is a bad habit in itself, and leads to the desire for other and
more injurious condiments.
10. Lime. This is the mineral substance which we
have spoken of before as entering very largely into the com-
position of the bones. It is the important element which
gives solidity and permanence to the framework upon
which the body is built. Calcium tri-phosphate, or "bone-
earth," is the chief ingredient of the bones and teeth, but
is found in the cartilages and other parts of the body in
smaller quantities. (Read Note 5.)
11. How does this substance find its way into the body?
Meat, milk, and other articles obtained from the animal
kingdom contain it, and it is abundantly stored away also
in the grains from which our bread is made, in wheat, rye,
and Indian corn. In early life, while the body is growing,
the supplies of this substance should be carefully provided.
The evil effects of the deprivation of it are too often and
painfully evident in the softening of the bones, and in the
predisposition to curvature of the spine delQmities which
are most deplorable and which continue through life.
12. Iron. This substance is probably the most abun-
dant and widely diffused of the metals. It is found in
9. Salt, hovr taken into the system? Its use in cooking ? Consumption?
10. Lime in the bones ? What does it impart ? Chief ingredient of the bones
and teeth ? Where else found ?
11. How does lime find its way into the body? Early life? Effect of it*
deprivation ?
1 2. Iron, its abundance and diffusion ? Where found ? What part of the blood
is it T How supplied to the system ? In case of loss of blood or wasting disease ?
THE CHEMISTRY OF FOOD. 57
most of the vegetables, and is a very important component
of animal tissues. It enters into the composition of hu-
man blood in about one part per thousand. Ordinarily,
the food conveys to the system enough iron for its use, but
it must sometimes be introduced separately as a remedy,
especially after great loss of blood, or after some wasting
disease. Under its influence the blood seems to be
rapidly restored, and a natural color of the lips and skin
replaces the pallor caused by disease.
13. Other Inorganic Substances. In addition to
the substances mentioned, the mineral kingdom supplies,
compounds of soda, potash, and magnesia, which are es-
sential for the use of the body. They occur in small
quantities in the body, and enter it in combination with
the various articles of diet.
14. Organic Substances. These substances are derived
from the vegetable and animal creations. They comprise
all those articles which are commonly spoken of as " food,"
and which are essential to sustain the body in life and
strength. They are divided into three groups, namely:
the Albuminoid substances, the Fats, and Sugars.
15. The Albuminoids. This class includes three im -
portant nutritive substances (I) Albumen, which gives it
its name; (2) Fibrin, including gluten; and (3) Casein.
These compounds constitute a large part of the human
body, and the food contains them in proportionally large
quantities. Their importance is so great, and the system
so promptly suffers from their absence, that they have been
styled the "nutritious substances." The properties which
they hold in common are, that they do not crystallize, and
have a jelly-like form, except when heat is applied to them,
when they harden, or coagulate.
1 3. Soda, potash, and magnesia ? How do they occur ?
14. Organic substances, whence derived ? What do they comprise ? Groups ?
15. The Albuminoid class, includes what? These compounds constitute
irhat) The food? Thir importance ? Their properties t
58 THE CHEMISTRY OF FOOD.
;
I 16. They likewise decompose, or putrefy, under the influ-
ence of warmth and moisture. Hence the decay of all
dead animal tissues. Cold arrests this process. It is well
known that milk, eggs, and the like, " keep" much longer
in winter than at other seasons. The bodies of elephants,
caught in the ice many hundred years ago, are occasion-
ally borne by the icebergs to the coast of Siberia, com-
pletely frozen, but preserved almost perfectly in form and
limb.
17. Albumen exists in milk, meat, the grains, and the
juices of many plants; but the purest form is obtained
from the white of egg. When we consider that an egg is
composed chiefly of albumen and water namely, six parts
in seven; and when we also consider the numerous, diverse,
and complex tissues the muscles, bones, internal organs,
bill, claws, and feathers with which the chick is equipped
on leaving his shell, we are impressed with the importance
of these apparently simple constituents of the food and
body. (Read Note 9, end of Chapter)
18. Fibrin is derived from meats, and exists in the
blood both of man and the lower animals. Gluten, 01
vegetable fibrin, resembles closely true fibrin, and is abun-
dantly furnished in wheat and other grains from which
flour is commonly made. Animal fibrin coagulates spon-
taneously when it is removed from the body, and thus
causes the " clotting" of the blood.
19. Casein is the curdy ingredient of milk, and a highly
important food-substance. Its coagulation in milk takes
place not from heat, but by the addition of an acid, and
also when milk becomes sour from exposure to the air. It
is commonly effected, however, by introducing a piece of
rennet, a preparation made from a calf s stomach. The
curds, or casein, may then be separated from the whey,
16. Decomposition? Effect of cold ? Illustrations? Elephants?
1 7. In what substances does albumen exist ? What further is said of the egg
18. Fibrin, gluten, clotting of the blood ?
19. Casein? Its coagulation ? Eft'ect of rennet ? Making of cheese*
THE CHEMISTRY OF FOOD. 59
and made into cheese, by pressing it sufficiently to drive
off the water.
20. The Fats or Oils. This is the second group of
organic foods. Those which are more solid are called fats:
the more fluid ones are the oils. Oleaginous substances
are supplied in both animal and vegetable food ; but, from
whatever source derived, they are chemically much alike.
They are insoluble in water, and yet they unite readily
with the watery fluids of the body, and are by them con-
veyed to its various parts for their nourishment. This is
due to their property of "emulsifying;" that is, they are
held in suspension, in a finely divided state, in water. Or-
dinary milk is an example of an emulsion. We know that
it contains fat; for butter is obtained from it, and, under
the microscope, the minute oil-globules may be distinctly
seen.
21. In our country and climate, and also in colder
climates, fatty articles of food are principally derived from
the animal creation, such as meat or flesh, milk and butter.
But most of the bread-stuffs contain more or less fat or oil;
Indian meal as much as nine parts in a hundred.
22. Among persons living in cold climates, the appetite
for oleaginous food is especially eager ; and they require
large quantities of it to enable them to resist the depress-
ing influences of cold. Since vegetation is scanty and
innutritions, and the waters of the frozen regions abound
in animal life, they must rely wholly upon a diet derived
from the latter source. The Esquimaux consumes daily
from ten to fifteen pounds of meat or blubber, a large
proportion of which is fat. The Laplander will drink
train-oil, and regards tallow-candles as a great delicacy.
In hot climates, on the contrary, where flourish the olive
20. What are the fats ? The oils ? How supplied ? How alike ? Emulsifying 7
Example ? How do we know it?
21. Whence are fatty articles of food derived?
22. Appetite of persons in cold climates? What do they require ? Upon wiia
roust thty jely T Why? Thw Esquimaux ? Laplander' Ollv<* and paluu r
60 THE CHEMISTRY OF FOOD.
and the palm, this kind of food may be obtained from
vegetable sources in abundant quantities. (Read Notes 4 a</8.)
23. The Sugars, or the Saccharine Substances.
These constitute the third, and last, group of the organic
substances, which are employed as food. This group em-
braces, in addition to the different kinds of Sugar, the
varieties of starch and gum, from whatever source derived.
The two substances last named do not, at first sight, pre-
sent many points of similarity to sugar; but they closely
resemble it in respect to their ultimate chemical composi-
tion, being made up of the same elements, in nearly the
same proportions. And their office in the system is the
same, since they are all changed into sugar by the processes
of digestion.
24. Sugar is chiefly of vegetable origin; the animal
varieties being obtained from honey and milk. The most
noticeable characteristic of this substance is its agreeable,
sweet taste, which makes it everywhere a favorite article of
food. But this quality of sweetness is not possessed by all
the varieties of sugar in the same degree ; that obtained
from milk, for instance, has a comparatively feeble taste,
but rather imparts a gritty feeling to the tonsrue. The
other important properties of sugar are, its power to
crystallize when evaporated from watery solutions, such as
the juices of many plants ; a tendency to ferment, by which
process alcohol is produced; and a ready solubility in
water. This latter quality renders it very easy of digestion,
and more so than any other of the saccharine group. It is
computed that the annual production of sugar, in all parts
of the world, is more than .one million of tons. The kind
of sugar that is in ordinary use, in this country, is prepared
from the juice of the sugar-cane, which contains eighteen
per cent, of sugar. In France it is manufactured from the
23. Which are the third of the organic groups? What do they embrace?
Points of resemblance ?
24 . Origin of the sugars ? Ordinary sugar ? Beetroot? Maple-sugar? Grape-
i-ugar ? Cane-sugar ?
THE CHEMISTRY OF FOOD.
Gl
beet root, which holds about nine per cent. ; the maple-tree
of our climate yields a similar sugar. The sweet taste of
fruits is due to the presence of grape-sugar: the white
grains seen on raisins belong to this variety. Cane-sugar
is more soluble than the latter, and has twice the sweeten-
; ng power. (Read Note 5.)
N 25. Starch. This is the most widely distributed of
/ the vegetable principles.
It is tasteless, inodorous,
and does not crystallize.
It consists of minute
rounded granules, which,
under the microscope,
reveal a somewhat uni-
form structure (Fig. 15).
Starch will not dissolve
in cold water, but in
boiling water the small
grains burst open, and
may then be dissolved
and digested.
K 26. The bread stuffs, wheat, corn, and rye flours, are
more than one-half starch. Eice^ which is the "staff of
life" to one-third of the human family, contains eighty
per cent. Unripe fruits have much starch in them,
which renders them indigestible when eaten uncooked;
for the grains of raw starch are but slightly acted upon
within the body. But, under the potent chemistry of the
sun's ray, this crude material is converted into sugar.
Thus are the fruits prepared by the careful hand of
Nature, so that when ripe they may be freely used without
further preparation,
ft 27. Gum is commonly found in those articles which
! 25. Starch, how widely distributed? Its qualities? Its constituents? Its
solubility?
26. How much starch in bread-stuffs ? In rieo? Unrine fruits? Ripe fruits?
27. Gum, where found? Its composition ? Gum Arabic?
FIG. 15. GRANULE? op POTATO STARCH.
62 THE CHEMISTRY OF FOOD.
also contain starch ; and has the same chemical composi-
tion as the latter, but is much less nutritious. In the
East, gum-arabic and similar substances are largely em-
ployed as food. Persons who travel by caravan across vast,
sandy deserts, find such substances well adapted to their
wants, since they are not perishable, and are easily packed
and carried.
I 28. Stimulating Substances. The three classes of
food-principles already considered the Albuminoids, the
Fats, and the Sugars comprise all the more important
organic ingredients of our food. There are, besides, a
great variety of coloring and flavoring matters that stim-
ulate or increase the appetite for food by appealing to th p
eye and taste; but they are not nutritious, and are quickly
separated from the truly useful substances, and do not
long remain in the body. Among these may be classed
spices, flavors of fruits, tea, coffee, and vegetable acids.
29. Necessity of a Regulated Diet. A great vari-
ety of experiments have been tried in order to test the rela-
t^ye value of the different nutritive principles. They have
been practised to some extent upon man, but chiefly upon
those inferior animals which require a similar diet to man.
30. By this means it has been demonstrated that first,
when any one of these substances is eaten exclusively, the
body is imperfectly nourished, and life is shortened. Dogs
fed exclusively upon either albumen, fat, or sugar, soon die
of starvation. Second, a diet long deprived of either of
these principles, is a fertile cause of disease; for example,
on ship-board, where fresh vegetables are not dealt out for a
long period, scurvy becomes prevalent among tiie sailors.
The y are, however, to a certain extent mutually convertible,
and tl us the missing article is indirectly supplied. For
28. The throe classes of food principles ? What besides? What is i-aid of
them ? Name the articles not nutritious.
29. What is said of experiments that have been tried?
30. What hfl* been tloinon-trnt'-d In the first place? Example? Second di--
mon ^ration f E*upie r *.. * thw illustration iu relation to convertibility.
THE CHEMISTRY OF FOOD. C>3
instance, sugar changes to fat in the body ; and hence, as
is well known, the " hands" on a sugar plantation grow
fat during the sugar season, by partaking freely of the
ripened juices of the Cane. (Read Note 10, end of Chapter.}
31. That is the best diet therefore which contains some
of each of these principles, in due proportion; and that is
the worst which excludes the most of them. The cravings
and experience of man had unerringly guided him to a
correct regulation of his diet, long before the chemistry
of food was understood ; so that his ordinary meals
long ago combined these various principles, the necessity
and value of which are now explained. (Read Notes n and 12,
end of Chapter.")
QUESTIONS FOR TOPICAL REVIEW.
PAGE
1. What is understood by the term food ? 53
2. What can you state in relation to the source of food ? 53
3. What discriminations and selections are necessary ? 53, 54
4. How can you tell the organic from the inorganic :-ubstances * 54
5. What relative position does water hold as an article of food ? 54
6. In what parts of the body is water found ? 54, 55
7. In what articles that we eat is it found ? 55
8. If you were required to go without water or solid food for a number of days,
which would you prefer to have, and why ? 55
9. What can you state of the importance of salt as an article of food ? 55, 56
10. How abundant is salt, and how does it find its way into the human sys-
tem ? 55, 56
11. What can you state of the importance of lime in the body ? 56
12. What, of the importance of iron ? 56, 57
13. What further is stater! of other inorganic substances ? 57
14. What in relation to organic substances ? *?
15. What can you state in relation to the albuminoids ? 57, 58
16. What, in relation to albumen ? ^
17. What, in relation to casein ? 58, 59
18. In relation to the fats or oils, and how generally consumed ? 59, 60
19. What do we understand by the sugars or saccharine substances ?
20. Sta'e what you can of sn<rar its origin and various qualities 60, 61
21. Of starch its varieties and qualities 61
22. Of the abundance of starch, and its importance as a food principle 61
23. What is stated in relation to stimulating substances ?
24. Of the necessity for regulation in diet ?
NOTES.
1. The only Natural Drink (p. 55, 15). "Water is the natural drink
or man, as it is of all organized beings. It enters more largely into his composi-
tion than any other substance, giving liquidity to the blood, moisture to all the
tissues," and serving as the great solvent of the body ; not less than two-thirds
of its weight being of that element. It seems as if all organic beings were so
much 'organized water.' "Soft water is more wholesome than hard, though
water moderately hard is not perceptibly injurious. When very hard, a part of
the salts of lime can readily be precipitated by boiling. As a rule, spring and
well-waters, if brought from deep fountains, are better and more wholesome than
running streams. Well-water, in towns and cities, unless brought from a great
depth, is wholly unfit for drinking and cooking. The immense quantity of
organic matter which permeate? every inch of the soil, for many feet in depth, pre-
cludes the possibility of water passing through it without being corrupted.
River-water, polluted by sewers, is as disgusting to the senses as it is destruc-
tive to health. The notion that impure water can be rendered more wholesome
by icing it is an erroneous one. Ice-cold drinks in summer, while the body is
heated, are capable of producing lifetime disease, and even instant death." J. B.
Black on the Ten Laws of Health.
2. Of Salt (p. 56, 1 8).
" Salt-cellars ever should stand at the head,
Of dishes, wheresoe'er a table's spread.
Salt will all poisons expurgate with haste,
And to insipid things impart a taste.
The richest food will be in great default
Of taste, without a pinch of sav'ry salt.
Yet of salt meats, the long-protracted use
Will both our sight and manhood, too, reduce;
On tables salt should stand both first and last,
Since, in its absence, there is no repast."
The Code of the School of Salernum.
" Animals will travel long distances to obtain salt. Men will barter gold for it ;
indeed, among the Gallas and on the coast of Sierra Leone, brothers will sell
their sisters, husbands their wives, and parents their children for salt. In the
district of Accra, on the gold coast of Africa, a handful of salt is the most val-
uable thing upon earth after gold, and will purchase a slave or two. Mnngo Park
tells us that with the Mandingoes and Bambaras the use of salt is such a luxury
that to say of a man, ' he flavors his food with salt,' it is to imply that he is
rich ; and children will suck a piece of rock-salt as if it were sugar. No stronger
mark of respect or affection can be shown in Muscovy, than the sending of salt
from the tables of the rich to their poorer friends. In the book of Leviticus it is
expressly commanded as one of the ordinances of Moses, that every oblation of
meat upon the altar shall be seasoned with salt, without lacking; and hence it is
called the Salt of the Covenant of God. The Greeks and Romans also used salt
in their sacrificial cakes ; and it is still used in the cervices of the Latin church
the 'parva mica,' 1 or pinch of salt, being, in the ceremony of baptism, put into
the child's mouth, while the priest says, 'Receive the salt of wisdom, and may it
be a propitiation to thee for eternal life.' Everywhere, and almost always,
indeed, it has been regarded as emblematical of wisdom, wit, and immortality. To
taste a man's salt, was to be bound by the rites of hospitality ; and no oath was
more solemn than that which was sworn upon bread and salt. To sprinkle the
meat with salt was to drive away, the devil, and to this day, among the super-
stitious, nothing is more unlucky than to spill the salt." Letheby on r ood.
3. Phosphate of Lime and other Inorganic Substances
(p. 56, ^ 10)." All food contains certain saline substances. If we burn a portion
NOTES.
of the flesh of any animal, we may drive off the carbon, oxygen, hydrogen, and
nitrogen, and ' ashes ' are left. These ashes are the saline and mineral (inorganic)
constituents of the animal. They exist in the blood and tissues, and are as
essential to the life of the animal as those other elements which were expelled
by heat. Like the latter they are constantly being used up aud can-fed off from
the body, and like them must be replaced by means of our food. Cooking, espe-
cially boiling, tends to dissolve away some of these salts, and care should be
taken to supply them by means of uncooked food, as fresh vegetables and fruits ;
milk also contains them. One of the most important of these inorganic sub-
stances is phosphate of lime, or ' bone earth,' as it is called, from the fact that
about forty per cent, of healthy bone is made up of it. When it is deficient,
the bones are soft and are liable to be bent by the actions of the muscles
attached to them, and a permanent deformity may be the consequence. This form
of lime is contained in wheat, barley, oats, and rye, and from these sources the
chief supply of it is derived. These plants require phosphate of lime for their
growth and the perfecting of their grains ; hence it is supplied artificially by
the farmer. A diet deficient in substances yielding the phosphate of lime is inju-
rious to man, and should be avoided. Its presence in wheat-flour accounts
in part for the fact that our ordinary loaf of bread makes so good a ' staff of life,'
and that it is, and has been, so widely used as an article of food by the strongest
and most vigorous races of mankind." Lankester's Manual.
4. The Necessity of Fat in the Food of Children (p. 60, 122).
"Children who dislike fat cause much anxiety to parents, for they are almost
always thin, and, if not diseased, are not healthy. If care be not taken, they
fall into a scrofulous condition, in which diseased joints, enlarged glands, gore
eyes, and even consumption occur ; and every effort should be made to overcome
this dislike. If attention be given to this matter of diet, there need be no anx-
iety about the possibility of increasing the quantity of food consumed, whilst the
neglect, the dislike, will probably increase until disease is produced. The chief
period of growth viz., from seven to sixteen years of age is the most important
in this respect, for a store of fat in the body is then essential. Those who are
inclined to be fat usually like fat in food, and then it may be desirable to limit its
use. Some who cannot eat it when hot like it when cold, and all should select
that kind which they prefer. Those living in Russia and Lapland devour very
large quantities, as seven pounds daily, and eat it even raw, while those dwell-
ing in hot countries use very little. It produces more heat than any other kind
of food. 1 ' Edward Smith on Health.
5. Why too much Sugar is Injurious (p. 61, 1 24). "Sugar is
very wholesome, and, as I told you, we want some in our diet. But children
will often eat too much sugar, just as they will eat too little fat. The harm it
does them is first, it is very apt to spoil the teeth; second, it takes away the
appetite for other food. If you are always eating sweet cakes and sugar plums,
you will not care for plain, nourishing diet. Now, what is best for us all is, to
have good appetites for wholesome food ; it will do more to keep us in health all
our lives than anything else ; and there is a great deal in getting the right habit."
Candies are frequently adulterated with plaster-of-paris, chalk, and certain forms
of earth, that are indigestible ; but worse than that, the coloring matters and
flavoring extracts that are used in the bright-tinted and fruity-flavored confec-
tionery are absolute poisons in many instances, euch as arsenic, copper, zinc,
lead, prussic and sulphuric acid. Berner's Lessons on Health (in part).
NOTES.
6. Tlie Circle of Organic Li'fe (p. 53, ^ 2). Man, as an animal, is chemi-
cally an oxidizing agent, reducing again to primitive forms the principles built up by
the vegetable world, and taken i.i by him either directly as vegetables, or indirectly
in the shape of the material of other animals. Without vegetable life animals
could not exist, and never could have existed ; side by side they grow and flourish,
indispensable to each other's existence ; the tree breaking up the exhaled carbonic
acid of the animal, the carbon being stored up in its increasing mass, while the
oxigen is returned again free and uncombined, to the atmosphere for the respira-
tory needs of the animal world. Round and round go the elementary bodies in
ceaseless change of form, nevertheless never more than they were at first and will
be at the last ; the atomic material of this planetary sphere being ever absolutely
the same in amount. The material of the bodies of Saul and his sons when burnt
by the men of Israel after their ignominious exposure at Bethshan, in consequence
of their defeat on Mount Gilboa, are circulating amongst us still ; it served others
before them, and has formed part of thousands since. It is quite within the bounds
of chemical possibility that some of the atoms contained in the fated apple of Eve,
may have lain in the material of the apple which revealed to Newton the law of
gravitation. Fothergill on the Maintenance of Health.
7. The Sustaining Power of Water (p. 55, ^ 5). Water is the most
reliable and grateful drink for man. Nature has many admixtures in the juices of
fruits, but none so satisfying to excessive thirst as pure water. It will even pro-
long life when nutritious food is not taken, as we have a well-known instance,
recorded by Dr. McNaughton, in the transactions of the Albany Institute of New
York for 1836. The case was that of a man who lived upon water alone for fifty .
three days. This he did while laboring under some delusion which impelled him
to abstain from all ordinary nourishment, water alone could he be induced to par-
take of. His strength was tolerably well sustained during the first six weeks ; h
was able, in fact, to go out of doors ; and even on the day of his death he was abl
to sit up in bed. Dr. James Knight.
8. The Effect of Climate oil tlie Appetite (p. 60, T 22). Climate has
an important influence on the quantity of food demanded by the system ; and
every one has experienced in his own person a considerable difference at different
seasons of the year. Travelers' accounts of the amount of food consumed by the
natives of the frigid zone are almost incredible. They speak of men eating a hun-
dred pounds of meat in a day ; and a Russian admiral, Saritcheff, mentions an
instance of a man who, in his presence, ate at a single meal a mess of boiled rice
and butter weiging 28 pounds. Although it is difficult to regard these statements
with entire confidence, the general opinion is undoubtedly well founded that the
appetite is greater in cold than in warm climates. Dr. Hayes, the Arctic explorer,
states, from his own observation, that the daily ration of the Esquimaux is from
12 to 15 pounds of meat, about one-third of which was fat. He once saw an
Esquimau consume ten pounds of walrus-flesh and blubber at a single meal,
which however lasted several hours, with the thermometer fo or 70 below zero.
Some members of his own party manifested a constant craving for fatty substances,
and were in the habit of drinking the contents of the oil-kettle with evident relish.
Flinfs Physiology.
9. Weight and Health (p. 58, t 17). -The weight of the body is very
generally assumed to be an infallible index or proof of the maintenance of a
healthy condition of the body ; and that food which keeps up the weight has been
regarded as satisfactory and nutritious. But this is not always a safe judgment,
owing to the property in water from innutritions food to make good the loss of
weight caused by the withdrawal of albumen and fat. The weight may remain
the same, while we are "losing flesh." Fat, also, may increase in bac.ly nour-
ished people, while the more essonMal element of albumen is diminishing : the fact
NOTES.
being that the badly fed are not always lighter than those who are well nourished.
And further, the feeling of satisfaction after eating is deceptive ; the Irish peasant
who consumes ten pounds of potatoes in a day feels quite satisfied, but is in
reality badly nourished by his diet containing three-fourths water. Prof. Voit, of
Munich.
10. The Effects of a Poor Diet (p. 63, 1 30.) The food of the pooi
in olden times was poor and scanty ; so much so, in fact, that their powers of
life were depressed ; and we believe this fact had much to do with the fearful
mortality of the plague throughout Europe during the middle ages. The lowef
classes, especially those living in crowded cities, and subsisting on the scanty
and monotonous diet that the historians ot the period describe, were the principal
sufferers. From 1296 to 1666, hundreds of thousands, were carried off by the most
fearful pestilences the earth has ever known. Rye in France and oats in England
were for generations the almost exclusive diet ; wheat was a luxury, which even
the rich might only indulge in at Christmas. Oats were known in Germany 2,000
years ago, and was probably the original bread-grain for all Europe. Dr. J.
Knight.
1 1 . Variety in Diet and in its Preparation Beneficial (p. 63, t 31).
"Every dietary should contain fresh vegetables. It is further necessary that
certain articles belonging to the same class be varied from day to day, otherwise
the appetite clogs. Beef should alternate with mutton, for example ; or variety
should be secured by different modes of cooking the same article. Indeed, it is
not too much to say that the art of cookery is a matter of national importance, not
only because it renders food palatable, but because the more it is studied and
practiced the greater is the economy which may be effected. It is chiefly in this
relation that beverages, condiments, etc., become such valuable dietetic adjuncts."
Wilson s Hand-book of Hygiene.
12. Some Experiments as to Food (p. 63, \ 31). Magendie made nu-
merous experiments on the inferior animals to test the value of different forms of
nutriment. He showed that a diet exclusively composed of starch and sugar
would not support life. So too, dogs confined to white bread and water died with
all the symptoms of starvation ; but on the military brown bread animals lived
pretty well, as this article contains a greater variety of the alimentary principles
Other experiments have given an account of geese limited to some one substance
All of them died ; the animal fed upon gum on the sixteenth day ; that fed with
sugar on the twenty-first day ; one fed with starch on the twenty-fourth day ; and
one fed with white of egg on the twenty-sixth day. In 1769, before these experi-
ments were performed, Dr. Stark, a young English physiologist, fell a victim at
an early age to ill-judged experiments on himself as to the effects of different
foods. He lived for forty-four days on bread and water, for twenty-nine days
on bread, sugar and water, and for twenty-four days on bread, water and olive
oil ; until finally his constitution became broken, and he died from the effects of
his experiments. Flinfs Physiology.
13. The Food Circle in Nature (p. 54, 1 3). There are the same ultimate
elements in flesh as in flour, the same in animals as in vegetables. The vegetable
draws food from the soil and from the air, and being fully matured, it or some
part of it is eaten by the animal. But in completing the circle, the vegetable
receives and thrives upon the animal itself, in whole or in part, or the refuse which
it daily throws off. The very bones of an animal are by nature or man made to
increase the growth of vegetables and really to enter into their structure, and
being again eaten, animals may be said to eat their own bones, and live on their
own flesh. Hence there is not only an unbroken circle in the production of food
from different sources, but even the same food may be shown to be produced
from itself. Surely this is an illustration of the fable of the young Phoenix arising
from the ashes of its parent. Edward Smith on Foods.
f
64 FOOD AND DRINK.
CHAPTER V.
FOOD AKD DRI^K.
Necessity for Food Waste and Repair Hunger and Thirst Amoum,
of Food Renovation of tJie Body Mixed Diet Milk Eggs Meat
Cooking Vegetable Food Bread The Potato Fruits Purity
of Water Action of Water upon Lead Coffee, Tea, and Chocolate
Effects of Alcohol.
1. Necessity for Food. Activity is everywhere fol-
lowed by waste. The engine uses up coal and water to
produce motion, the stream wears away its bank, the
growing corn-blade draws tribute from the soil. When the
human body acts, and it is always in action during life, some
of its particles are worn out and thrown off. This waste
must constantly be repaired, or the body suffers. In this
fact is seen the necessity for food. The particles, thus worn
out, being henceforth useless, are removed from the body.
Our food and drink are rapidly transformed into a new
supply of living, useful material, to be in turn used up
and replaced by a fresher supply.
2. Waste and Repair. In this way the healthful
body, though always wasting, is always building up, and
does not greatly change in size, form, or weight. At two
periods of life the processes of waste and repair are not ex-
actly balanced. In early life the process of building up is
more active, and in consequence the form is plump, and
the stature increases. Repair now exceeds waste. On the
other hand, when old age comes on, the wasting process is
more active, the flesh and weight diminish, the skin falls
in wrinkles, and the senses become dull. Only during the
prime of life from about twenty to sixty years of age is
the balance exact between loss and gain. (Read Note 7.)
1. What follows activity? Examples? Necessity for food?
2, Give the theory i relation to \vaete ami repair,
FOOD AND DRINK. 65
3. Hunger and Thirst. When the system is deprived
of its supply of solid food during a longer time than usual,
nature gives warning by the sensation of hunger, to
repair the losses that have taken place. This sensation
or pain appears to be located in the stomach, but it is really
a distress of the system at large. Let a sufficient quantity
of nourishment be introduced into the system in any other
way than by the mouth, and it will appease hunger just as
certainly as when taken in the usual manner.
4. The feeling of thirst, in like manner, is evidence that
the system is suffering from the want of water. The
apparent seat of the distress of thirst is in the throat ; but
the injection of water into the blood-vessels is found to
quench thirst, and by the immersion of the body in water,
the skin will absorb sufficient to satisfy the demands of the
system. The length of time that man can exist without
food or drink is estimated to be about seven days. If water
alone be supplied, life will last much longer ; there being
cases recorded where men have lived twenty days and over,
without taking any solid food. (Read Note i.)
5. Quantity of Food. The quantity of food required
varies greatly, according to the individual and his mode of
life. The young, and others who lead active lives, or who
live in the open air, require more food than the old, the
inactive, or the sedentary. Those who live in cold regions
require more than the inhabitants of hot climates. Habit,
also, has much to do with the quantity of food required.
Some habitually eat and drink more than they actually
need, while a few eat less than they should.
6. The average daily quantity of food and drink for a
healthy man of active habits is estimated at six pounds.
This amount may be divided in about the following pro-
3 . System deprived of food ? Warning ? What i? the pain ? How proved ?
4. Feeling of thirst? Seat of the pain? How proved? Time a person can
exist without food ?
5. Amount of food required? The young and others? Those living in hot
and cold climates ? Habits ?
6. Quantity of food daily? How divided? Compare with, the weight of the body ?
66 FOOD AKD DRINK.
portions : the mineral kingdom furnishes three and one-
half pounds, including water and salt; the vegetable king-
dom, one and one-half pounds, including bread, vegetables,
and fruits; the animal kingdom, one pound, comprising
meat, eggs, butter, and the like. This quantity is about
one twenty-fourth the weight of the body, as it is generally
computed; the average weight of an adult man being placed
at 140 pounds. A man, therefore, consumes an amount of
solid and liquid nutriment every twenty-four days equal
in weight to that of his body, a corresponding amount
being excreted, or removed from the system in the same
time. (Read Notes 3 and 8, end of Chapter.}
7. Renovation of the Body. By this process, so far
as weight is concerned, the body might be renewed every
twenty-four days; but these pounds of food are not all real
nutriment. A considerable portion of that which we eat
is innutritions, and though useful in various ways, is not
destined to repair the losses of the system. An opinion
has prevailed that the body is renewed throughout once in
seven years; how correct this may be it is not easy to
decide, but probably the renovation of the body takes
place in a much shorter period. Some parts are very
frequently renewed, the nutritive fluids changing more or
less completely, several times during the day. The muscles,
and other parts in frequent exercise, change often during a
year; the bones not so often, and the enamel of the teeth
probably never changes after being once fully formed. (m.z.)
8. Mixed Diet. The habits of different nations in
respect to diet exhibit the widest and strangest diversity.
The civilized, cook their food, while savages often eat
it in a raw state. Some prefer it when fresh, others allow
it to remain until it has become tainted with decay,
Those dwelling in the far north subsist almost wholly on
7. How often then might the body be renewed? Why is it not? Opinion?
How correct ? What further is stated ?
8. Habits of nations ? Give the different cases.
FOOD AND DRINK. 67
animal food, while those living in hot climates have boun-
tiful supplies of delicious fruits with which to satisfy all
their bodily wants. One race subsists upon the banana,
another upon the blubber r? seals. In temperate climates,
a diet composed partly of vegetable and partly of animal
food is preferred. (Read Note 9, end of Chapter?)
9. The important point to consider is, however, not one
of origin, but whether the chemical principles (mentioned
in the last chapter) enter into the composition of the diet
A purely vegetable diet maybe selected which would contain
all the principles necessary to sustain life. It is recorded of
Louis Cornaro, a Venetian noble, that he supported himself
comfortably for fifty-eight years on a daily allowance of
twelve Dunces of vegetable food, and about a pint of light
wine. On the other hand, the food of John the Baptist,
consisting of "locusts and wild honey," is an example of
the sustaining power of a diet chiefly animal in its origin.
10. In our climate, those who lead active lives crave an
allowance of animal food; and it has been found by ex-
perience that with it they can accomplish more work and
are less subject to fatigue, than without it. Among na-
tions where an exclusively vegetable diet is employed, indi-
gestion is a disorder especially prevalent. (Read Note 4.)
11. The necessity for occasionally changing or varying
the diet, is seen in the fact that no single article comprises
all the necessary principles of food, and that the contin-
uous use of any one diet, whether salt or fresh, is followed
by defective nutrition and disease. There is one exception
to this rule : in infancy, milk alone is best calculated
to support life ; for then the digestive powers are incom-
pletely developed, and the food must be presented in the
simplest form possible. It should also be remembered
9. The point to consider? Vegetable diet ? Louis Cornaro ? John the i:ap
tist ?
1 0. What has been found in our climate ? Exclusive vegetable diet ?
11. Necessity for change in diet ? Continuous use of the same diet? Excey
tion? Why? Too rich diet? Horses?
68 FOOD AND DRINK.
that too rich diet is injurious, just as truly as one that is
inadequate. When the food of horses is too nutritious, in-
stinct leads them to gnaw the wood-work of their mangers .*
12. Different Articles of Diet Milk. Milk is the
earliest nutriment of the human race, and in the selection
and arrangement of its constituents, may be regarded as a
model food, no other single article being capable of sustain-
ing life so long. Cow's milk holds casein, one of the albu-
minoids, about five parts in one hundred ; a fatty principle,
when separated, known as butter, about four parts ; sugar
of milk four parts; water and salts eighty-seven parts.
The casein and fatty substance are far more digestible in
milk than after they have been separated from it in the
form of cheese and butter.
13. Since milk, in itself, is so rich an article of food,
the use of it as a beverage is unwise, unhess the quantity
of the other articles consumed be reduced at the same
time. The milk sold in cities is apt to be diluted with
water. The way to detect the cheat is by testing the
specific gravity of the article. Good milk is about 1030;
skimmed milk, 1035 ; but milk diluted one-fifth is 1024.
An instrument called the lactometer is also used, by which
the amount of cream present is ascertained.
14. Eggs. The egg is about two-thirds water, the bal-
ance is pure albumen and fat in nearly equal proportions.
The fat is in the yolk, and gives it its yellow color. Eggs
contain none of the sugar principles, and should be eaten
with bread or vegetables that contain them. Soft-boiled
eggs are more wholesome than those which are hard-boiled
or fried, as the latter reqjiire longer time to digest.
15. Meats. The meats, so called, are derived from
the muscular parts of various animals. They are most im-
12. Milk as a model food ? Cow's milk? The constituents when separated ?
13. Milk as a beverage? Milk sold in cities ? How to detect the cheat ?
14. Composition of eggs? Yolk? How should eggs be eaten? Why? How-
boiled ? Why ?
15. Meats, whence derived ? Why important ? Flesh of yoiin,? animal^ ?
(* Read Note 10, end of Chapter, ^
FOOD AND DRINK. 69
portant articles of food for adults, inasmuch as they are
richly stored with albuminoid substances, and contain
more or less fat. Such food is very nourishing and easily
digested if eaten when fresh, veal and pork being excep-
tions. The flesh of young animals is more tender and, in
general, more digestible than that of older ones. All meat
is more tough immediately after the killing of the animal,
but improves by being kept a certain length of time.
16. Some persons prefer flesh that has begun to show
signs of decomposition, or is unmistakably putrid. By
some, venison is not considered to have its proper flavor
until it is tainted. In England, people prefer mutton
that is in a similar condition, just as on the continent of
Europe many delight in cheese that is in a state of decom-
position. In certain less civilized countries flesh is not only
eaten uncooked, but in a mouldy, rotten condition. The
use of such food is not always immediately injurious, but
it predisposes to certain diseases, as indigestion and fevers.
17. Cold is one means of preserving meat from decay.
In the markets of northern Russia, the frozen carcases of
animals stand exposed for sale in the winter air for a con-
siderable time, and are sawn in pieces, like sticks of wood,
as the purchases are made; such meat, when thawed,
being entirely fit for food. Beef and pork are preserved
by salting down in brine, and in this condition may be
carried on long voyages or kept for future use. Salted
meat is not as nutritious as fresh, since the brine absorbs
its rich juices and hardens its fibres. Long continued use
of salt meats, without fresh vegetables, gives rise to the
disease called scurvy, formerly very prevalent on ship-
board and in prisons ; but now scarcely known.
/ 18. Cooking. The preparation of food by the agency
16. Preference of persons? Venison? Mutton? Cheese? Uncooked flesh?
17. Cold as a preserver? Meat in Russia? Beef and pork, how preserved?
Salted meat as food ? Scurvy ?
18. The antiquity of the custom of cooking food? Object of cookirig ? The
oyster ? ftaw meat as an occasional food ?.
70 FOOD AXD DRIXK.
of fire is of almost universal practice, even among the
rudest nations. The object of cooking is to render food
more easy of digestion by softening it, to develop its
flavor, and to raise its temperature more nearly to that of
the body. A few articles of flesh -food are eaten un-
cooked in civilized lands, the oyster being an instance.
Raw meat is occasionally eaten by invalids with weak
digestive powers, and by men training for athletic con-
tests.
19. In boiling meat, the water in which it is placed
tends to dissolve its nutrient juices. In fact, the cooking
may be so conducted as to rob the meat of its nourish-
ment, its tenderness, and even of its flavor. The proper
method, in order to preserve or promote these qualities, is
to place the meat in boiling water, which, after a few
minutes, should be reduced in temperature. In this way
the intense heat, at first, coagulates the exterior layers of
albumen, and imprisons the delicate juices ; after that,
moderate heat best softens it throughout. When soup is
to be made, an opposite course should be pursued ; for
then the object is to extract the juices and reject the fibre.
Meat, for such purpose, should be cut in small pieces and
put into cold water, which should then be gradually raised
to boiling heat. (Read Note ii, end of Chapter)
20. Roasting is probably the best method of cooking
meat, especially "joints" or large pieces, as by this process
the meat is cooked in its own juices. Roasting should
begin with intense heat, and be continued at a moderate
temperature, in order to prevent the drying out of the
nutritious juices, as by this process an outer coating or
crust of coagulated albumen is formed. During this pro-
cess the meat loses one-fourth of its weight, but the loss
is almost wholly water, evaporated by the heat. Too
19. Effect of boiling meat? How may the cooking be done? The proper
method ? Effect ? Making of soup ?
20. Roasting ? How should it be done? Give the philosphy of the process.
Fiying ?
FOOD AXD DRINK. 71
intense or prolonged heat will dry the meat, or burn it.
Frying is the worst possible method, as the heated fat, by
penetrating the meat, or other article placed in it, dries
and hardens it, and thus renders it indigestible.
21. Trichina. It should be remembered that ham,
sausages, and other forms of pork, should never be eaten
in a raw or imperfectly cooked condition. The muscle of
the pig is often infested by a minute animal parasite, or
worm, called trichina spiralis. This worm may be intro-
duced alive into the human body in pork food, where it
multiplies with great rapidity, and gives rise to a painful
and serious disease. This disease has been prevalent in
Germany, and cases of it occur from time to time in this
country.
22. Fish. The part of fish that is eaten is the muscle,
just as in the case of the meats and poultry. It closely
resembles flesh in its composition, but is more watery.
Some varieties are very easy of digestion, such as salmon,
trout, and cod: others are quite indigestible, especially
lobsters, clams, and shell-fish generally. A diet in which
fish enters as the chief article, is ill adapted to strengthen
mind or body, while its continued use is said to be the
fertile source of nearly every form of disease of the skin.
Some persons are so constituted that they can eat no kind
of fish without experiencing unpleasant results.
23. Vegetable Food. The list of vegetable articles
of diet is a very long one, including the grains from which
our bread-stuifs are made, the vegetables from the garden,
and the fruits. All the products of the vegetable king-
dom are not alike useful. Some are positively hurtful;
indeed, the most virulent poisons, as strychnia and prussic
acid, are obtained from certain vegetables. Again, of such
21 . What is " Trichina ?" How guarded asrainst ?
22. What part of fish is eaten ? What does it resemble ? Fish as food for
digestion ? Fish as a diet ?
23. List of vegetable articles? Usefulness of the different vegetables?
Strychnia ? What further is said in relation to the nourishing and other qualities
ufvccctablcH?
72 FOOD AND DRINK.
articles as have been found good for food, some are more
nourishing than others: some require very little prepara-
tion for use, while others are hard and indigestible, and
can only be used after undergoing many preparatory pro-
cesses. Great care must therefore be exercised, and many
experiments made, before we can arrive at a complete
knowledge in reference to these articles of diet. Tea,
coffee, and other substances from which drinks are made,
are of vegetable origin.
24. Bread. Wheat is the principal and most valuable
kind of grain for the service of man. Bread made from
wheat-flour has been in use for many hundreds of years,
and on this account, as well as because of its highly
nourishing properties, has been aptly called " the staff of
Jife." We never become tired of good bread as an article
of daily food.
The white kinds of flour contain more starch and less
gluten than the darker, and are therefore less nutritious.
The hard-grain wheat yields the best flour. In grinding
wheat, the chaff or bran is separated by a process called
" bolting." Unbolted flour is used for making brown or
Graham bread. (Read Note 5.)
25. The form of bread most easily digested is that which
has been " leavened," or rendered porous by the use of
yeast, or by some similar method. Unleavened bread
requires much more mastication. Hot bread is unwhole-
some, because it is not firm enough to be thoroughly mas-
ticated, but is converted into a pasty, heavy mass that is
not easily digested.
26. Wheaten bread contains nearly every principle requi-
site for sustaining life, except fat. This is commonly added
in other articles of diet, especially in butter, " bread and
gutter," consequently, forming an almost perfect article of
24. Wheat? "Staff of life?" White flour? Hard-grain wheats? Bolting?
Graham bread ?
25. Leavened bread ? Unleavened? Hot bread ?
26.. Wheaten bread ? Bread and butter ? Experiment on the dog ?
FOOD AND DRINK. 73
food. The following experiment is recorded : " A dog
eating ad libitum of white bread, made of pure wheat, and
freely supplied with water, did not live beyond fifty days.
He died at the end of that time with all the signs of
gradual exhaustion." Death took place, not because there
was anything hurtful in the bread, but because of the
absence of one or more of the food-principles.
27. The Potato. The common or Irish potato is the
vegetable most extensively used in this country and Great
Britain. Among the poorer classes in Ireland it is the
main article of food. While it is not so rich in nutritious
substances as many others, it has some very useful qualities.
It keeps well from season to reason, and men do not weary
of its continuous use. It is more than two-thirds water,
the balance being chiefly starch, with a little albumen.
28. The sweet potato differs from the white or common,
in containing more water and a small proportion of sugar.
The common potato and the tomato belong to the same
botanical order as tht " nightshades," but do not possess
their poisonous qualities, unless we except potatoes that
are in the process of germination or sprouting, when they
are found injurious as food.
29. Fruits. These are produced, in this country, in
great abundance, and are remarkable alike for their variety
and delicious flavor ; consequently they are consumed in
large quantities, especially during the warmer months.
The moderate use of ripe fruits, in their season, is
beneficial, because they offer a pleasant substitute for the
more concentrated diet that is used in cold weather. The
amount of solid nutriment they contain is, however,
small. The percentage of water in cherries is seventy-
five, in grapes eighty-one, in apples eighty two. Unripe
fruits contain starch, which, during the process of ripening,
27. State what is said of the Irish potato ?
28. Sweet potato ? Nightshades? Potatoes when {Terminating ?
29. Fruits? Use of ripe fruit? Nutriment they contain? Starch in unripo
fruits? Cooking of unripe fruits ?
FOOD AND DRINK.
is converted into sugar. Such fruits are indigestible and
should be avoided : cooking, however, in part removes the
objections to them.
30. Pure Water. It is important that the water we
drink and use in the preparation of food should be pure.
It should be clear and colorless, with little or no taste or
smell, and free from any great amount of foreign ingre-
dients. Chemically pure water does not occur in nature :
it is only obtained by the condensation of steam, carefully
conducted, and is not as agreeable for drinking purposes
as the water furnished by springs and streams. Rain-water
is the purest occurring in nature ; but even this contains
certain impurities, especially the portion which falls in the
early part of a shower; for in its descent from the clouds,
the particles floating in the air are caught by the falling
drops.
31. Water from springs and wells always contains more
or less foreign matter of mineral origin. This imparts to
the drink its pleasant taste the sparkle, or "life," coming
from the gases absorbed by the water during its passage
under ground. The ordinary supply of cities is from some
pure stream or pond conveyed from a distance through
pipes, the limpid fluid containing generally only a small
amount of impurity. Croton water, the supply of New
York City, is very pure, and contains only four and a half
grains to a gallon : the Ridgewood water of Brooklyn holds
even less foreign matter.
32. Drinking- water may contain as large a proportion as
sixty to seventy grains per gallon of impurity, but a much
larger quantity renders it unwholesome. The mineral
spring waters, used popularly as medicines, are highly
charged with mineral substances. Some of them, such as
30. How should drinking-water bo as regards color and smell ? Chemically
pure water ? How obtained ? Agre^abJenese of perfectly pure water ?
31. Spring and well water? Whence the sparkle, or life? The water supply
of cities ? Croton wate ? Ridgewood ?
32. Impurities in drinking-water? Mineral springs ?
FOOD AND DRINK. 75
the waters at Saratoga, contain three hundred grains and
more to the gallon. (Read Note 6, end of Chapter?)
A. 33. Action of Water upon Lead. The danger of
fusing water that has been in contact with certain metals is
well known. Lead is one of the most readily soluble, and
probably the most poisonous of these substances in common
use. When pure water and an untarnished surface of lead
come m contact, the water gradually corrodes the metal,
and soon holds an appreciable quantity of it in solution.
When this takes place the water becomes highly injurious:
the purer the water, and the more recent the use of the
metal, the greater will be the danger. (Note 12, end of Chapter.)
A 34. In cities, lead pipes are commonly used to convey
/ water through the houses ; lead being also used in the con-
' struction of roofs, cisterns, and vessels for keeping water
and other liquids. After the articles of lead have been in
use several months, the danger of lead-poisoning dimin-
ishes. An insoluble coating of the sulphate of lead forms
upon the exposed surface, thus protecting it from further
corrosion. It is, however, a wise precaution, at all times to
reject the water or other fluid that has been in contact
with leaden vessels over night, or for a number of hours.
Allow the water in pipes to run freely before using.
35. Coffee. This is an important addition to diet, and
if moderately used is beneficial to persons of adult age.
As commonly employed, it consists of an infusion in boil-
ing water of the roasted and ground berry. The water
extracts certain flavoring and coloring matters, but that
which gives it its peculiar stimulant qualities is the alka-
loid caffein. With most persons its action is that of a
gentle stimulant, without any injurious reaction. It pro-
duces a restful feeling after exhausting efforts of mind <?,;
33. What is stated of the action of water upon lead 1
34. Lead in pipes and other things t Advice 'i What takes place after the arti,
cles of lead have been used much ? What is wise 1
35. Coffee as an article of diet? Of what does it consist? How does the
water affect the coffee 1 The peculiar stimulant ? How doc* it affect mo*l per.
oonat
76 FOOD AND DRINK.
body; it tranqnilizes, but does not disqualify for labor;
and hence it is highly esteemed by persons of literary pur-
suits.
36. Another property of coffee is, that it diminishes the
waste of the tissues, and consequently permits the per-
formance of excessive labor upon an economical and in-
adequate diet. This has been tested among the miners of
Belgium. Their allowance of solid food was below that
found necessary in prisons and elsewhere; but, with the
addition of about four pints of coffee daily, they were en-
abled to undergo severe labor without reducing their mus-
cular strength. The caravans which traverse the deserts
are supported by coffee during long journeys and length-
ened privation of food. Among armies it is indispensable
in supplementing their imperfect rations, and in relieving
the sense of fatigue after great exposure and long marches.
When taken with meals, coffee is also thought to promote
digestion.
37. Tea. The effects of tea-drinking are very similar
to those of coffee, and are due to a peculiar principle called
thein. This principle is probably the same as that found
in coffee, caffein, since the chemical composition of both
is precisely alike. Tea, as a beverage, is made from the
dried leaves of the plant by the addition of hot water; if
the tea is boiled, the oil which gives it its agreeable flavor
is driven off with the steam. There are two kinds of
tea the black and the green : the latter is sometimes in-
jurious, producing wakefulness and other nervous symp-
toms. The excessive use of either coffee or tea will cause
wakefulness.
38. During Dr. Kane's expedition in the Arctic regions,
the effects of these articles were compared. "After re-
36. Another property of coffee? Miners of Belgium? The Caravans?
Among armies ? Taken with meal* ?
37. Effects of tea-drinking? Peculiar principle? The tea beverage, how
made ? Black and green tea ? Excessive use of tea or coffee ?
38. Experiments made during Kane's expedition?
FOOD AND DRINK. 77
peated trials, the men took most kindly to coffee in the
morning and tea in the evening. The coffee seemed to
continue its influence throughout the day, and they seemed
to grow hungry less rapidly than after drinking tea, while
tea soothed them after a day's hard labor, and the better
enabled them to sleep. They both operated upon fatigued
men like a charm, and their superiority over alcoholic
stimulants was very decided."
39. Chocolate is made from the seeds of the cocoa-tree,
a native of tropical America. Its effects resemble some-
what those of tea and coffee, but it is very rich in nutri-
ment. Linnaeus, the botanist, was so fond of this beverage,
that he gave to the cocoa-tree the name, Theobroma " the
Food of the Gods." Its active principle is theobromin.
40. Alcohol. The list of beverages that are consumed
for the sake of the alcohol they contain is a very long one.
Their use is almost universally prevalent, every civilized
nation, and nearly every barbarous one, having its favorite
alcoholic drink ; and, as a general rule, the nations which
stand the highest in civilization have the greatest varieties
of these beverages, at the same time using them the most
intelligently and wisely.
41. The wines and malt liquors that contain a small
amount of alcohol are produced by fermentation. The
beverages that hold a large proportion of alcohol, the
"ardent spirits," are made by distillation. Enormous
quantities of grains and fruits are thus yearly diverted
from their proper uses as food ; some of these being corn,
wheat, rye, barley, potatoes, and rice ; also the grape, apple,
pear, peach, sugar-cane, cherry, fig, and orange. Wine, the
fermented juice of the grape, has been in use from time
immemorial, while the introduction of distilled liquors
dates from a comparatively recent period.
39. State what is said of chocolate.
40. Use of alcoholic drink?, how general? The rule "riven ?
41 . Tht: beverages produced by fermentation ? The ardent spirits ? Grains and
fruits employed ? Long use of wine ? Of distilled liquors ?
78 FOOD AJSJ> JJULNK.
42. What is the physiological action of alcohol ? Its first
and most evident action is stimulation : this effect is tran-
sient, and is followed by a variable degree of depression
At first it sharpens the appetite and quickens digestion,
but its habitual use impairs both. This stimulation is
efficient in giving the system an artificial strength during
some temporary derangement, and in enabling the endur,
ance of unusual fatigue or exposure. The experience oi
Dr. Hayes, and other explorers of the polar regions, is that
alcohol does not enable the body to resist the influence of
cold, but, on the contrary, is always injurious.
43. Another property it has in common with tea and
coffee. It supports the powers of life, economizes food, and
retards the waste of tissues; in other words, it " banks the
fires," and prevents their burning wastefully. On this
principle we explain the restorative influence of wines or
liquors during exhausting diseases, in convalescence, and
after excessive labors of mind or body.
44. Pure alcohol, or an excessive quantity of ardent
spirits, is an undoubted poison, and has been frequently
known to produce fatal results. Stimulants in moderate
quantities have been thought to increase strength, and in
this view they have been called "alcoholic foods." This is
not now conceded by scientific men. The prevailing opin-
ion is, that they serve no useful purpose as an article of
diet, and that their beneficial influence is limited to cases
where the system is enfeebled, where some unnatural de-
mand is made upon the vital powers, or where the supply
of food is insufficient. Hence, while alcohol has not the
power to build up, it may obstruct the process of pulling
down.
42. Describe the action of alcohol upon the human system ? Experience of
Dr. Hayes and others ?
43. Another property of alcohol ? How do we explain the restorative influence
of wines and liquors ?
44. Alcohol, a poison ? Moderate stimulants? Prevailing opinion ? Hence?
HEVIEW QUESTIONS. 79
QUESTIONb 7OR TOPICAL REVIEW.
PAGB
1. How is the necessity for food shown ? 04
2. To what process of waste and repair is> the body constantly subjected ? 64
3. How do you account for the sensations ot hanger and thirst ? G5
4. What further can you state having relation to the subject ? 05
5. What can you state in regard to the quantity of food required for the
support of life ? 65, G6
6. What circumstances change the needs of persons, old a:id young, as re-
gards food and drink ? 65 i 57
7. What becomes of all the food and drink we consume ? 66
8. What further can you state iu relation to the process of renovation through
which the body passes ? 66
9. What can you state of the habits of nations in respect to diet ? 66, 67, 69
10. What in relation to the selection of articles for food ? 67
11. What as respects the necessity for changing or varying the diet ? 67
12. What has been proved as regards animal food ? 67
13. Of what importance is milk as an article of food ? 67, 68
14. What are the constituents of milk ? . . 68
15. What can you state of eggs as an article of food? 68
16. Of the meats, so called, as an article of food ? 68, 69
17. What effect does cold have upon meats ? 69
18. In what ot her way may beef and pork be preserved ? 69
19. What can you state of salted meat as food, and of its continued use ? 09
20. What change doe? meat undergo in the cooking ? 70, 71
21. What directions are given for boiling meat ? 70
22. What for roasting, and with what results? 70, 71
83. What is said about the frying of meats? 7i
24. Give the statement in relation to trichina 7'
25. State what is said in relation to fish 71
26. What is stated of the usefulness and other properties of the products of
the vegetable kingdom ? 71, 72
27. What further is said of vegetable food ? 71, 72
28. Why is bread made of wheat flour so important as an article of food ? 72
29. State whatever else you can in relation to bread 72, 73
30. Give the statement respec' ing the potato - 73
31. What is stated of fruits, the use of them, their nutritious qualities, etc.? 73, 74
32. How general is the existence of perfectly pare water ? 74
33. What is stated in relation to drinking water ? 74, 75
34. How does the action of water upon lead affect lead ? 75
35. What further can you state on the subject? 75
3(i. What properties has coffee as an article of diet ? 75. 7G
37. In what circumstances has coffee been found peculiarly beneficial ? 76
38. What comparison is made between coffee, tea, and chocolate ? 76
39. How are the wines, and malt and other alcoholic beverages produced ? 77
40. What articles are employed in their production ? TT
41. Describe the physiological action of alcohol. T8
42. What comparison is made between tea, coffee, and alcohol ? 78
43. What can yon state of alcohol, as a poison, a stimulant, and article of diet ? 73
44. What, then, can be said of alcohol as a recommendation ? 78
NOTES.
1. Hunger and Thirst (p. 65, 1 4). " We none of n object to a
pharp-set appetite ; that is by no means unpleasant, especially when there is food
at hand; but if this is not the case it soon becomes a craving passion, a strong
impelling power. The cravings of hunger have done much for this world ; ' look
where we may, we see it as the motive power which sets the vast array of human
machinery in action.' Hunger is also the incentive which directs our attention to
the system's need for food, and if it be sharp enough the most loathsome substances
are greedily devoured. By it has man, and civilized man, too, been driven to feed
upon the putrid corpse of his comrade. Hunger is one of the great forces in action,
in the preservation of the life of the individual ; and the fear of it is one of the
s-trongest incentives to action. But the pangs of hunger are tolerable in compari-
son with the tortures of raging thirst. In fact, so terrible are the latter that they
form one of the crudest tortures which man can inflict on man; so cruel a tor-
ture, indeed, that it has rarely been used, except in cases of bitter personal ani-
mosity, by others than brutal Eastern tyrants, or bigots under the influence of
religious fanaticism. 1 ' Fothergill on the Maintenance of Health.
2. The Renewal of the Body (p. 66, 17). "To meet these constant
chemical changes, material is taken in, in the form of food and drink, which is being
constantly assimilated, and so nutrition and repair are conducted. The rapidity
with which these changes are carried on is much greater than is usually supposed.
Paley, in his 'Natural Theology,' states that seven years are requisite for the per-
fect renewal of the body ; and this statement, owing partly to the mysticism associa-
ted with t he number 7, is generally accepted and believed. The time really is rather
months than years ; but it is absurd to fix a time which must necessarily vary iu
different individuals, being much less in the infant than in the aged, in the active
than the indolent ; widely different, too, in various tissues, from the epithelium lin-
ing of the glands of the stomach, renewed several times in each act of digestion,
to the enamel of the tooth, which is probably never renewed during a lifetime. 1 "
3. A Lifetime Allowance of Food (p. 66,1 6). ' M.Soyer, in his 'Mod-
ern Housewife,' makes a calculation as to how much food an epicure of 70 years of
age has consumed. This imaginary epicure, who is supposed to be a wealthy per-
sonage, is placed by him on Primrose Hill at ten years old and told to look around
him at the vast assemblage of animals and other objects he will in the course of
a lifetime send down his throat the sight of which is, of course, described as
appalling. Among the other things, he is to devour 30 oxen, 200 sheep, 100 calves,
200 lambs, 50 pigs, 1,200 fowls, 300 turkeys, 263 pigeons, 120 turbot, 140 salmon,
30,000 oysters, 5.745 Ibs. of vegetables, 243% Ibs. of butter, 24,000 eggs, and 4^
tons of bread, besides fruits, sweetmeats, etc., and 49 hogsheads of wine, 548
gals, of spirits, and about 3,000 gals, of tea and coffee. This is a mere outline of
what we are told is destined to be consumed. To show there is no exaggeration,
Soyer assures us that he has from experience made up a scale of food for the day
for a period of 60 years, and it amounts to 33% tons of meat, farinaceous food, and
vegetable?, etc." Journal of Chemistry.
4. A Mixed Diet afford* the best Results (p. 67, 1 10). "The mixed
diet to which the inclination of man in temperate climates seems unusually to
lead him, when circumstances allow that inclination to develop itself freely,
appears to be fully conformable to the construction of his dental and digestive
apparatus, as well as to his instinctive cravings. And whilst on the one hand it
maybe freely conceded to the advocates of 'vegetarianism,' that a well-selected
vegetable diet is capable of producing, in the greatest number of individuals, the
highest physical development of which they are capable, it may, on the other hand,
be affirmed with equal certainty, that the substitution of a moderate proportion
NOTES.
of animal Ae*h is in no way injurious; but, so far as our evidence at present
extends, this seems rather to favor the highest mental development. And we can
scarcely avoid the conclusion that the Creator, by conferring on man a remarka-
ble range of choice, intended to qualify him for subsisting on those articles of
diet, whether animal or vegetable, which he finds most suitable to his tastes and
wants." W. B. Carpenter on the Principles of Physiology.
5, Bread (p. 72, 124). "The health and power of a nation, as of an army,
depend greatly on its food. The quality of bread in any nation, community, or
family is a pretty good measure of its civilization. No one can entirely dispense
with it. Good or bad, in some form it must be had. So it is, and has been from
the earliest records of the race, and so it will doubtless continue. Leavened or
fermented bread is as old as the time of Moses, and its value has been fully tested.
Whatever be the precise action of the leaven, it transforms the grain by partial
decomposition of its original elements, and leaves as its resultant what all men in
all ages have approved. Is the art of making good, honest, leavened, Bible bread
lost in Massachusetts, as some of our friends declare ? Baker's bread is almost uni-
versally adulterated. Bread hastily made in families is mixed in a varietyof ways,
with a variety of chemicals, and is generally imperfectly cooked. Very often the
elements of wheat and fat which the body demands (a wise and witty clergyman
of the last generation used to say, 'bread is the staff of life, but bread and butter
is a gold-headed cane') are furnished in underdone pastry, made from flour and
hog's lard. Any family can have good bread who will take the pains. It involves
not more than ordinary skill and judgment. It ' is to be found on the continent of
Europe on all the great lines of travel, and is as common among the people in
France and Germany as it is rare with us.' The materials for an honest, wholesome
loaf are simple and not expensive. The value of time and labor required for
kneading the dough are the only difficulties, and these we would not undervalue;
they are in many families very serious, and not easily overcome." Derby on the
Food of Massachusetts.
6. Impure Water Spreads Disease (p. 75, t 32). "In the year 1867,
three millions of pilgrims, of whom a handful had come from a cholera district,
assembled at Hurdwar, a few miles from the spot where the Ganges escapes from
the Himalayas. On the 12th of April the three millions resolved to bathe and
drink. 'The bathing-place of the pilgrims was a space 650 feet long by 30 feet
wide, shut off from the rest of the Ganges by rails. Into this long and narrow in-
closure pilgrims from all parts of the encampment crowded as closely as possible
from early morn to sunset ; the water within this space, during the whole time,
was thick and dirty partly from the ashes of the dead, brought by surviving rela-
tives to be deposited in the water of their river god, and partly from the washing of
the clothes and bodies of the bathers. Now, pilgrims at the bathing ghaut, after
entering the stream, dip themselves under the water three times or more, and
then drink of the holy water, whilst saying their prayer. The drinking of the
water is never omitted ; and when twoormore members of a family bathe together,
each from his own hand gives to the other water to drink. On the evening of the
next day, the 13th of April, eight cases of cholera were admitted into one of the
hospitals at Hurdwar. By the 15th, the whole of this vast concourse of pilgrims
had dispersed,' carrying the cholera in every direction over India; it attacked the
British troops along the various routes, it passed the northern frontier, got into
Persia, and so on into Europe, where it will work its wicked will for some time
to come. That is a sample of the mischief water can do in the way of spreading
disease." London Medical Press.
NOTES.
7. The Waste of the Body (p. 64,! 2.}. " In the physical life of man
there is scarcely such a thing as rest the numberless organs and tissues which
compose his frame are undergoing perpetual change, and in the exercise of the
function of each some part of it is destroyed. Thus, we cannot think, feel or
move without wasting some proportion, great or small, according to the energy
of the act, of the apparatuses concerned such as brain, nerve or muscles. Now
this waste-product cannot remain in its original situation, where it would not only
be useless dross, but also obstructive and injurious. Such old material is being
daily removed from our bodies to the average amount of three or more pounds ; and
that an equal quantity of new shall take its place is the first piinciple of alimenta-
tion. To express it in commercial language, the income must be equal to the
expenditure ; and in each of us the amount of this exchange must in a lifetime
reach many tons. This tissue-change is so complete, that not a particle of our
present body will be ours a short time hence ; and we will be, as I have lately
seen it prased, like the knife which, after having had several new blades, and at
least one new handle, was still the same old knife to its owner. We are, in fact,
constantly ' moulting.' " Mapother's Lectures on Public Health.
8. A Daily Ration for an Adult Man (p. 66, ^6). " We may arrive
at something like an average daily diet by taking the case of the man in good
health, weighing 154 Ibs., and measuring 5 feet 8 inches in height. Simply to
maintain his body, without loss or gain in weight, his ration of food should not
contain less, during 24 hours, than the following proportions and quantities of the
main ingredients :
THE AVERAGE DAILY DIET FOR AN ADULT.
FOOD SUBSTANCES.
PER CENTUM.
WEIGHT.
Water
81 <
Ibs. oz. grs.
r g 020
Albuminoids or flesh formers. ..
3-9
4 no
ii 178
Fat
Phosphates, potash, salts, etc
3
170
100.
6 13 128
" Water, it will be remembered, enters into the composition of every article of
food as well as in the liquids we drink. In reality, the weight of the dry food we
take will exceed that given above ; chiefly for the reason that they do not come to
us pure and unmixed with fibrous material and gelatine, whose use in nourishing
the body is limited and uncertain." Kensington Museum Hand-book on Food.
9. Different Effects of Animal and Vegetable Food (p. 67. \ 8).
u Raw meat gives fierceness to animals, and would do the same to man. This is
so true that the English, who eat their meat underdone, seem to partake of this
fierceness more or Isss, as shown in pride, hatred and contempt of other nations."
De La Mettrie.
" The carnivora are in general stronger, bolder and more pugnacious than the
herbivora on which they prey ; in like manner, those nations who live on vege-
table food differ in disposition from such as live on flesh." Liebig.
NOTES.
A bear at Giessen was very gentle when fed on bread, but a day or two on meat
made him savage and dangerous.
" The hunted deer will outrun the leopard in a fair open chase, because the
force supplied to its muscles by vegetable food is given out continuously for a
long time ; but in a sudden rush at a near distance, the leopard will infallibly
overtake the deer, decause its flesh food stores up in the blood a reserve of force
capable of being given out instantaneously in exceedingly rapid muscular action."
Haughtorfs A nimal Mechanics.
10. A Summary Concerning Diet (p. 68,1 ). " The food on which the
man who would be healthy should live, should be selected so as to ensure variety
without excess. Animal food should not be taken ottener than twice daily. The
amount of animal and vegetable food combined should not exceed 30 ounces in the
24 hours ; and for the majority of persons an average of 24 ounces of mixed solid
food, a third only of which should be animal, is sufficient. All animal foods should
be eaten while they are fresh, and after they have been well cooked. The habit
of eating underdone flesh is an almost certain cause of parasitic disease. The
amount of fluid taken, in any form, should not exceed the average of 24 ounces
daily. Water is the only natural beverage." Dr. B. W. Richardson, The Diseases
of Modern Life.
1 1 . Cooking Paves the Way for Easy Digestion (p. 70, 1 19). The
objects to be obtained by cooking meat are : i. To coagulate the albumen and
blood of the tissues, so as to render the meat agreeable to the sight 2. To develop
flavors, and to make the tissue crisp, as well as tender, and therefore more easy
of mastication and digestion. 3. To secure a certain temperature, and thus to be
a means of conveying warmth to the system. 4. To kill parasites hi the tissues of
the meat
The action of heat should not be continued after these objects are accomplished,
as the meat will thereby be rendered indigestible. If a piece of meat be placed in
water which is briskly boiling, a crust, so to speak, is formed by the rapid coagu-
lation of the albumen upon and near the surface ; so that the juice of the meat can
not escape, nor the water penetrate its interior. If, on the other hand, the meat
be put in cold water and slowly heated, the albumen is gradually dissolved, and
exudes into the water, making good soup, but leaving the meat poor and tasteless.
Even in roasting meat the heat must be strongest at first, and it may then be much
reduced. The juice which, as in boiling, flows out, evaporates, in careful roasting,
from the surface of the meat, and gives to it the dark brown color, the lustre, and
the strong aromatic taste of roast meat. All baked and roasted fatty foods are apt
to disagree with delicate stomachs ; and it is often remarked that, although bread
and butter, boiled puddings, boiled fish, or boiled poultry can be eaten freely
without discomfort, yet toast and butter, or meat pies and pastry, or fried fish, or
roasted fowl will disagree with the stomach. Letheby on Food.
12. L.ead in Drinking- Water (p. 75, t 33). The danger of using lea.
for pipes or cisterns is now well known ; the case of the late royal family o
France at Claremont having made the matter notorious. In this case there wai
one-tenth of a grain in the gallon, and one-third of the persons who drank thi
water were affected. But even one-hundredth of a grain per gallon has produce
palsy in those who drank this impurity habitually. It is remarkable that tU
Thames water will at one time dissolve lead, and not at another.
Health Lectures.
80 DIGESTION.
CHAPTER VI.
DIGESTION".
The Principal Processes of Nutrition The General Plan of Digestion
Mastication The Teeth Preservation of the Teeth Insalivation
The Stomach and the Gastric Juice The Movements of the
Stomach Gastric Digestion The Intestines TJie Bile and Pan-
creatic Juice Intestinal Digestion Absorption by means of Blood-
vessels and Lactcals The Lymphatic or Absorbent System The
Lymph Conditions which affect Digestion The Quality, Quan-
tity, and Temperature of the Food The Influence of Exercise and
f.
'
1. Nutrition. The great design of food is to give
nutriment or nourishment to the body. But this is not
accomplished directly, as the food must first pass through
certain preparatory changes, as follows : (1), Digestion, by
which the food is reduced to a soluble condition; (2), Ab-
sorption, by which, when digested, it is imbibed into the
blood; (3), Circulation, which carries the enriched blood
to the various parts of the system; and (4), Assimilation,
by which each tissue derives from the blood the materials
necessary for its support.
2. By these means the sustaining power of food is grad-
ually developed and employed, and the vital machinery
kept in working order, somewhat after the manner of the
steam-engine. To operate the latter, the force imprisoned
within the coal and water is set free and converted into
motion by the combustion of the fuel and the vaporization
of the water. It will be seen, however, when we come to
study these operations in the human body, that they are
conducted silently and harmoniously, with marvellous deli-
cacy and completeness, and without that friction, and con-
1 . Design pf food ? How accomplished ?
2. Sustaining power of food ? Simile of the engine ? Operation in tho human
body ?
DIGESTION.
81
loss of power, which attend the working of the
most perfect machinery of mini's invention.
./ 3. General Plan of Digestion. The great change
which food undergoes in digestion is essentially a reform-
ing process, reducing articles of
diet, which are at first more or
less solid, crude, and coarse, to
a liquid and finely comminuted
condition, suitable for absorption
into the blood. The entire pro-
cess of digestion takes place in
what is called the alimentary
canal, a narrow, tortuous tube,
about thirty feet in its entire
length. This canal begins in
the mouth, extends thence down-
ward through the gullet to the
stomach (a receptacle in which
the principal work of digestion
is performed), and thence omvard
through the small and large in-
testines.
4. The stomach and intestines
are situated in the cavity of the
abdomen (Fig. 16, 0, and Fig. 2?), FlG 16> _ 8ECTIoy OF TFIE - TRUNK
and OCCUpV about two-thirds of SHOWING THE CAVITIES OP THE
,. mi ,' T -i ,1 CHEST AND ABDOMEN.
its space. I he action to wh icli the Ai cavity of chest ;
food is subjected in these organs g' Sme? m
is of two kinds mechanical and D < E ' s P inal ' lumn -
chemical. By the former it is crushed, agitated, and car-
ried onward from one point to another; by the latter it is
changed in form through the solvent power of the various
digestive juices.
3. Change of food in digestion? Process of digestion? Describ-* '*a: Mmen-
tary canal.
4. Situation of th ptomach and intestines ? Action cf the food ? M jhanic&l
action ? Chemical ?
82"
DIGESTION.
5. Mastication. As soon as solid food is taken into
the mouth, it undergoes mastication, or chewing. It is
caught between the opposite surfaces of the teeth, and by
them is cut and crushed into very small fragments. In
the movements of chewing,
the lower jaw plays the chief
part; the upper jaw, having
almost no motion, acts sim-
ply as a point of resistance,
to meet the action of the
former. These movements
of the lower jaw are of three
sorts: a vertical or cutting,
a lateral or grinding, and a
to-and-fro or gnawing mo-
tion.
6. The teeth are composed
of a bone-like material, and
are held in place by roots
running deeply into the jaw.
The exposed portion, or
"crown," is protected by a
thin layer of enamel (Fig.
17, ), the hardest substance
in the body, and, like flint, is capable of striking fire with
steel. In the interior of each tooth is a cavity, containing
blood-vessels and a nerve, which enter it through a minute
opening at the point of the root (Fig. 19).
tv 7. There are two sets of teeth ; first, those belonging to
the earlier years of childhood, called the milk teeth, which
are twenty in number and small. At six or eight years of
age, when the jaw expands, and when the growing body
requires a more powerful and numerous set, the roots of
FIQ. 17. SECTION op A TOOTH.
a, Enamel; , Cavity; cc, Roots;
d, Body of the Tooth.
5. Describe the process of mastication ? How many and what movements ?
6. Composition of the teeth? Enamel of the teeth? Interior of teeth?
1. The milk teeth ? The permanent troth 1
DIGESTION.
83
the milk teeth are absorbed, and the latter are "shed," or
fall out, one after another (Fig. 15), to make room for the
permanent sut.
FIG. 18. SECTION or THE JAWS.
1' 2' 3' 4 5', The Milk Teeth ; 1" to 8", The Germs of the Permanent Set.
8. There are thirty- two teeth in the permanent set,
many being in one jaw as the other. Each half-jaw has
eight teeth, similarly shaped and arranged in the same
order : thus, two incisors, one canine, two bicuspids, and
three molars. The front teeth are small, sharp, and chisel-
edged, and are well adapted for cutting purposes; hence
their name incisors. The canines stand next, one on each
side of the jaw; these receive their name from their resem-
blance to the long, pointed tusks of the dog (Fig. 19).
8, 9. Nurnbev of tueth ? How distributed ?
84
DIGESTIOK.
A 9. The bicuspids, next in order, are larger and have a
/ broader crown than the former ; while behind them are
the molars, the largest and most powerful of the entire set.
These large back teeth, or "grinders," present a broad,
rough surface, suitable for holding and crushing the food.
FIG. 19. SECTION OF THE JAWS RIGHT SIDE.
V, A, N, Veins, Arteries, and Nerves of the Teeth. The root of one tooth in each
jaw is cut vertically to show the cavity and the blood-vessel*, etc., within it.
1 to 8, Permanent Teeth.
The third molar, or " wisdom tooth," is the last to be cut,
and does not appear until about the twenty-first year.
DIGESTION. 85
The order of arrangement of the teeth is indicated by the
following dental formula:
M *^- M
B-
'
10. It is interesting, at this point, to notice the different
forms of teeth in different animals, and observe how ad-
mirably their teeth are suited to the respective kinds of
food upon which they subsist. In the carnivora, or flesh-
feeders, the teeth are sharp and pointed, enabling them
both to seize their prey, and tear it in pieces ; while the
herbivora, or vegetable- feeders, have broad, blunt teeth,
with rough crowns, suitable for grinding the tongh grasses
and grains upon which they feed. Human teeth partake
of both forms ; some of them are sharp, and others are
blunt; they are therefore well adapted for the, mastication
of both flesh and vegetables. Hence we argue that,
although man 'may live exclusively upon either vegetable
or animal food, he should, when possible, choose a diet
made up of both varieties.
11. Preservation of the Teeth. In order that the
teeth shall remain in a sound and serviceable condition,
some care is of course requisite. In the first place, they
require frequent cleansing ; for every time we take food,
some particles of it remain in the mouth ; and these, on
account of the heat and moisture present, soon begin to
putrefy. This not only renders the breath very offensive,
but promotes decay of the teeth.
10. Different forms of teeth ? Human teeth ? The inference ?
1 1 . Cleaning of teeth ? Effects of not cleaning ?
80 DIGESTION".
'
'
The saliva, or moisture of the mouth, undergoes a
putrefactive change, and becomes the fertile soil in which
a certain minute fungus has its growth. This fluid, too., if
allowed to dry. in the mouth, collects upon the teeth in the
form of an unsightly, yellow concretion, called tartar.
To prevent this formation, and to remove other offensive
substances, the teeth should be frequently cleaned with
water, applied by means of a soft tooth-brush. The de-
struction of the tartar fungus is best effected by the use
of a weak solution of carbolic acid.
13. Again, it should be borne in mind that the enamel,
Nature's protection for the teeth, when once destroyed, is
not formed anew; and the body of the tooth thus exposed,
is liable to rapid decay. On this account, certain articles
are to be guarded against; such as sharply acid substances
that corrode the enamel, and hard substances that break
or scratch it as gritty tooth powders, metal tooth picks,
and the shells of hard nuts. Sudden alternations from
heat to cold", when eating or drinking, also tend to crack
the enamel.
^ 14. Insalivation. When the morsel of food i& cut and
'ground by the teeth, it is at the same time also intimately
mixed with the saliva, or fluids of the mouth. This con-
stitutes the second step of digestion, and is called insaliva-
tion. The saliva, the first of the digestive solvents, is a
colorless, watery, and frothy fluid. It is secreted (i. e.
separated from the blood) partly by the mucous mem-
brane which lines the mouth ; but chiefly by the salivary
glands, of which there are three pairs situated near the
mouth.
15. These glands consist of clusters of very small
12. Effects upon the saliva? Formation of tartar? How prevented? How
destroyed ?
13. Destruction of the enamel!' How guarded against?
14. Mixing of food with the saliva ? What is the. saliva ? How secreted ? The
salivary glands ?
15. The flow of saliva ? The thought of food. ? Anxiety and gr'ef ? Animals
fed upon dry and, course food ?
DIGESTION.
pouches, around which a delicate network of blood-vessels
is arranged: they empty into the mouth by means of
little tubes, or
ducts. The flow
from these glands
is at all times suf-
ficient to maintain
a soft and moist
condition of the
tongue and mouth;
but when they are
excited by the pres-
ence and taste of
food,
forth
they
the
pour
saliva
PIG. 20. STRUCTURE OP A SALIVARY GLAND.
more freely. Even the mere thought of food will at
times cause the saliva to flow, as when the appetite is
stimulated by the sight or smell of some savory article ; so
that the common expres-
sion is correct that " the
mouth waters" for the fa-
vorite articles of food.
Anxiety and grief prevent
its flow, and cause "the
tongue to cleave to the
roof of the mouth." In
the horse and other ani-
mals, that feed upon dry
and coarse fodder, and re-
-, -i FIG. 21. THE HEAD OF A HOKSE, showing the
quire an abundant SUp- large salivary gland (a), its duct (6), the
i r* v n 3 i muscles of mastication (c. d. e,f, and a).
ply of saliva, we find large
salivary glands, as well as powerful muscles of mastication.
A 16. The mingling of the saliva with the food seems a
simple process, but it is one that plays an important part
1 6, Importance of the process ? The first place ? The second ? The third ?
88 DIGESTION.
a
',
in digestion. In the first place, it facilitates the motions
of mastication, by moistening the food and lubricating the
various organs of the mouth. Secondly, it prepares the
way for other digestive acts : by the action of the teeth,
the saliva is forced into the solid food, softens the harder
substances, and assists in converting the whole morsel into
a semi-solid, pulpy mass, that can be easily swallowed, and
readily permeated by other digestive fluids. The saliva
also, by dissolving certain substances, as sugar and salt,
develops the peculiar taste of each ; whereas, if the tongue
be dry and coated, they are tasteless. Hence, if substances
are insoluble, they are devoid of taste.
17. Finally, the saliva has the property of acting chemi-
' cally upon the food. As we have before stated (Chap. IV.),
Starch, as starch, cannot enter the tissues of the body ; but,
in order to become nutriment, must first be changed to
grape sugar. This change is, in part, effected by the saliva,
and takes place almost instantly, whenever it comes in con-
tact with cooked starch. This important function is due
to an organic ingredient of the saliva called ptyalin.
This substance has been extracted from the saliva by
the chemist, and has been found, by experiment, to
convert into sugar two thousand times its own weight of
Starch. (Read Note I, end of Chapter)
18. Importance of Mastication and Insaliva-
tion. Each of these processes complements the other,
and makes the entire work available; for, by their joint
action, they prepare the food in the best possible mannei
for further digestive changes. The knowledge of these
preliminary functions will appear the more important,
when we reflect that they are the only ones which we can
regulate by the will. For, as soon as the act of swallowing
begins, the food not only passes out of sight, but beyond
17. Its final importance? Starch? How effected ? PtyaUn .
18. Each of the processes? Why is a knowledge of the <ligestive functions
important ? How shown ?
DIGESTION. 89
control ; and the subsequent acts of digestion are conse-
quently involuntary and unconsciously performed.
i!9. It is generally known that rapid eating interferes
th digestion. How does this occur ? In the first place,
in rapid eating, the flow of the saliva is insufficient to
moisten the solid parts of the food, so that they remain too
hard and dry to be easily swallowed. This leads to the
free and frequent use of water, or some other beverage, at
meals, to "wash down" the food, a most pernicious prac-
tice. For these fluids, not only cannot take the place of
the natural digestive juices, but, on the contrary, dilute
and weaken them.
/ 20. Secondly, the saliva being largely the medium of the
' sense of taste, the natural flavors of the food are not devel-
oped, and consequently it appears comparatively insipid.
Hence the desire for high-seasoned food, and pungent
sauces, that both deprave the taste and over excite the
digestive organs. Rapid eating also permits the entrance
of injurious substances which may escape detection by the
taste, and be unconsciously received into the system. In
some instances, the most acrid and poisonous substances
have frequently been swallowed " by mistake," before the
sense of taste could act, and demand their rejection.
1 21. Thirdly, the food, being imperfectly broken up by
the teeth, is hurried onward to the stomach, to be by it
more thoroughly divided. But the task thus imposed upon
the stomach, it is not at all adapted to perform ; so that the
crude masses of food remain a heavy burden within the
stomach, and a source of distress to that organ, retarding
the performance of its legitimate duty. Hence -persons
who habitually eat too rapidly, frequently fall victims to
dyspepsia. Rapid eating also conduces to overeating.
The food is introduced so rapidly, that the system has not
19. Rapid eating ? Describe the process and effects.
20. Loss of taste ? Another effect of rapid eating ? Mistakes?
2 1 . Effect of imperfectly broken food iu the fetomach ? Dyspepsia ? Over-
eatic..' 1
90
DIGESTION.
time to recognize that its real wants are met, and that its
losses have been made good; and hence the appetite con-
tinues, although more nutriment has been swallowed than
the system requires, or can healthfully appropriate.
22. The Stomach. As soon as each separate portion
of food is masticated and insalivated, it is swallowed ; that
is, it is propelled down-
ward to the stomach,
through a narrow mus-
cular tube about nine
inches in length, called
the oesophagus, or gulv*
let (Fig. 23). The
stomach is the only
large expansion of the
digestive canal, and ia
the most important or-
gan of digestion. It is
a hollow, pear-shaped
pouch, having a ca-
pacity of three pints,
in the adult. Its walls
are thin and yielding,
and may become un-
naturally distended, as
in the case of those
who subsist on a bul-
ky, innutritious diet,
and of those who habitually gormandize.
23. The stomach has also two openings; that by which
food enters, being situated near the heart, is called the
cardiac, or heart orifice; the other is the pylorus, or
" gatekeeper," which guards the entrance.to the intestines,
PIG. 22. SECTION OF CHEST AND ABDOMEN.
A, Heart. D, The Liver.
B, The Lungs. E, Large Intestine.
C, Stomach. G, Small Intestine.
t2. Gullet? Describe the stomach and its location. Effects of gormandizing?
3. Heart-orifice? Gatekeeper? Coins, etc.? Indication <>f the soft and
yielding texture of the stomach ?
DIGESTION.
91
and, under ordinary circumstances, permits only such
matters to pass it as have first been properly acted upon
in the stomach. Coins, buttons, and the like are, however,
readily allowed to pass, because they can be of no use if
retained. The soft and
yielding texture of this
organ the stomach
indicates that it is not
designed to crush and
comminute solid articles
of food.
24. The Gastric
Juice. We have seen
how the presence of food
in the mouth excites the
salivary glands, causing
the saliva quickly to
flow. In the same man-
ner, when food reaches -
the stomach, its inner --
lining, the mucous mem-
brane, is at once excited
to activity. At first its
surface, which while the
stomach is empty pre-
sents a pale pink hue,
turns to a bright red
color, for the minute
blood-vessels which
course through it, are filled with blood. Presently a clear,
colorless, and acid fluid exudes, drop by drop, from its nu-
merous minute glands or "tubules," until finally the surface
is moistened in every part, and the fluid begins to mingle
with the food. This fluid is termed the gastric juice.
FIG. 23. THE ORGANS OP DIGESTION.
O, (Esophagus. I, Small Intestines.
S, Stomach. C, Large Intestines.
L, Liver. P, Pancreas.
M, Pylorus. N, Spleen.
G, Gall-bladder.
What ie meant by the gastric juice ?
92 DIGESTION.
25. The gastric juice is the proper solvent of certain
articles of food, especially those belonging to the albu-
minoid class. This solvent power is due to its peculiar in-
gredient, pepsin; in digestion, this substance acts like a
ferment; that is, it induces changes in the food simply by
its presence, but does not itself undergo change. The acid-
ity of the gastric juice, which is due to lactic acid, is not
accidental; for we find that the pepsin cannot act in an
alkaline solution that is, one which is not acid or neutral
The quantity of gastric juice secreted daily is very large
probably not less than three or four pints at each meal
Though this fluid is at once used in the reduction of the
food, it is not lost; since it is soon re-absorbed by the
stomach, together with those parts of the food which it
has digested and holds in solution.
^. 26. Movements of the Stomach. The inner coat-
ing of the stomach is the mucous membrane, which, as we
have seen, furnishes the gastric juice. (Next to this coating
lies another, called the muscular coat, composed of invol-
untary muscular fibres, some of which run circularly, and
others in a longitudinal direction. These expand to ac-
commodate the food as it is introduced, and contract as it
passes out. In addition, these fibres are in continual mo-
tion while food remains in the stomach, and they act in
such manner that the contents are gently turned round
from side to side, or from one end of it to the other.
27. By these incessant movements of the stomach,
called the peristaltic movements, thes, gastric juice comes
in contact with all parts of the fbod:^ We are, however,
not conscious that these movements take place, nor have
we the power to control them. When such portions of the
food as are sufficiently digested approach the pylorus, it
25. What is the office of the gastric juice? Acidity of the gastric juice!
Quantity of gastric juice used ? What becomes of it ?
26. Muscular coat of the stomach? Expansion and contraction of its fibres?
Action of the fibres?
27. Peristaltic movements? What if said of our consciousness of and power
over these movements ? Describe thu movements of the pylorus.
DIGESTION. 93
expands to allow them to pass out, and it closes again to
confine the residue for further preparation.
28. The knowledge of these and other interesting and
instructive facts has been obtained by actual observation ;
the workings of the stomach of a living human being have
been laid open to view and examined the result of a re-
markable accident. Alexis St. Martin, a Canadian voyageur>
received a gun-shot wound which laid open his stomach,
and which, in healing, left a permanent orifice nearly an
inch in diameter. Through this opening the observer
could watch the progress of digestion, and experiment with
different articles of food. Since that occurrence, artificial
openings into the stomach of the inferior animals have
been repeatedly made, so that the facts of stomach-digestion
are very well ascertained and verified. (Read Note 2.)
29. Gastric Digestion. What portions of the food
are digested in the .stomach ? It was formerly thought
that all the great changes of digestion were wrought here,
but later investigation has taught us better. We now know
that the first change in digestion takes place in the mouth, in
the partial conversion of starch into sugar. We also know
that, of the three organic food principles (considered in
Chapter IV.) two the fats and the sugars are but slightly
affected by the stomach ; but that its action is confined to
that third and very important class, from which the tissues
are renewed, the albuminoids. A few articles need no
preparation before entering the system, as water, salt, and
grape-sugar. These are rapidly taken up by the blood-
vessels of the stomach, which everywhere underlie ifo
mucous membrane in an intricate and most delicate net-
work. In this way the function of absorption begins.
30. The albuminoid substances are speedily attacked and
28. How has the knowledge and the workings of the stomach been ascertained ?
St. Martin ? How else ?
29. What was formerly thought ? What do we now know ? What elae do we
now know? Water, salt, and sugar? Absorption?
30. Albuniinose ? The process ? Cayme ?
DIGESTION.
digested by the gastric juice. From whatever source they
are derived, vegetable or animal, they are all transformed
into the same digestive product, called albuminose. This is
very soluble in water, and is in part absorbed by the blood-
vessels of the stomach. After a longer or shorter time,
varying from one to five hours, according to the individual
and the quantity and quality of his food, the stomach will
be found empty. Not only the unabsorbed digested food,
but also those substances which the stomach could not
digest, have passed little by little through the pylorus, to
undergo further action in the intestines. At the time of its
exit the digested food is of a pulpy consistence, and dark
color, and is then known as the chyme. (Read Note 6.)
^ 31. The Intestines. The intestines, or "bowels,"
are continuous with, the stomach, and consist of a fleshy
tube, or canal, twenty-five feet in length. The small
intestine, whose diameter is about one inch and a half, is
twenty feet long and very tortuous. The large intestine is
much wider than the former, and five feet long (Fig. 23).
The general structure of these organs resembles that of the
stomach. Like it, they are provided with a mucous mem-
brane, or inner lining, whence flow their digestive juices;
and, just outside of this, a muscular coat, which propels
the food onward from one point to another.
32. Moreover, both the intestines and stomach are envel-
in the folds of the same outer tunic or membrane, called
the peritoneum. This is so smooth and so well lubricated,
that the intestines have the utmost freedom of motion.
In the small intestines, the work of digestion is completed,
the large intestine receiving from them the indigestible
residue of the food, and in time expelling it from the body.
33. Intestinal Digestion. As soon as the food
f passes the pylorus and begins to accumulate in the upper
N x oped
31. What are the intestines? The small intestines? The lar<je intestines?
Their structure ?
32. Peritoneum ? The work of digestion ?
35. Tbc prepuce of food iu the mtcatiuuci ? Bile?
DIGESTION". 95
part of the intestines, it excites the flow of a new digestive
fluid, which enters through a small tube, or duct, about
three inches below the stomach. It is formed by the union
of two distinct fluids the bile and the pancreatic juice.
The bile is secreted by the liver, which is the largest gland
of the body, and is situated on the right side and upper
part of the abdomen (Fig. 22). The bile is constantly
formed, but it flows most rapidly during digestion. Dur-
ing the intervals of digestion it is stored in the gall-bladder,
a small membranous bag attached to the under side of the
liver. This fluid is of a greenish-yellow color, having a
peculiar smell, and a very bitter taste. (Read Note 3.)
34. The pancreatic juice is the product of a gland called
i\\Q2)ancreas, situated behind the stomach. This fluid is col-
orless, viscid, and without odor. Like the digestive juices
previously described, it owes its solvent power to its pecu-
liar ferment principle, called pancreatin. By the joint
action of these fluids, the fatty parts of the food are pre-
pared for absorption. By previous steps of digestion the
fats are merely separated from the other components of the
food; but here, within the intestines, they are reduced to a
state of minute division, or emulsion, resembling the con-
dition of butter in milk, before it has been churned.
There results from this action a white and milky fluid,
termed the chyle, which holds in solution the digestible
portions of the food, and is spread over the extensive
absorbent surface of the small intestines.
35. The mucous membrane of the intestines, also,
secretes or produces, a digestive fluid by means of numer-
ous "follicles," or minute glands; this is called the in-
testinal juice. From experiments on the inferior animals,
it has been ascertained that this fluid exerts a solvent influ-
ence over each of the three organic food principles, and in
this way may supplement and complete the action of the
34. The pancreatic juice ? The joint action of tho^e fluids ?
35. The raucous membrane ? Experiments on inferior animals T
96 DIGESTION.
r
fluids previously mentioned, viz.: of the saliva in convert-
ing starch into sugar, of the gastric juice in digesting the
albuminoids, and of the pancreatic juice and bile in
emulsifying the fats.
36. Absorption. With the elaboration of the chyle,
the work of digestion is completed ; but, in a certain sense,
the food is yet outside of the body ; that is,- the blood is not
yet enriched by it, and it is not in a position to nourish the
tissues. The process by which the liquefied food passes out
of the alimentary canal into the blood is called absorption.
This is accomplished in two ways ; first, by the blood-vessels.
We have seen how the inner membrane of the stomach is
underlaid by a tracery of minute and numerous vessels,
and how some portions of the food are by them absorbed.
The supply of blood-vessels to the intestines is even
greater; particularly to the small intestines, where the
work of absorption is more actively carried on.
37. The absorbing surface of the small intestines, if con-
sidered as a plane surface, amounts to not less than half a
square yard. Besides, the mucous membrane is formed in
folds with an immense number of thread-like prolongations,
called vittiy which indefinitely multiply its absorbing capa-
city. These minute processes, the villi, give the surface
the appearance and smoothness of velvet; and during
digestion, they dip into the canal, and, by means of their
blood-vessels, absorb its fluid contents, just as the spojigt-
oles which terminate the rootlets of plants, imbibe moisture
from the surrounding soil.
38. Secondly, absorption is also effected by the lacteals, a
set of vessels peculiar to the small intestines. These have
their beginnings in the little villi just mentioned, side by
side with the blood-vessels. These two sets of absorbents
run in different courses, but their destination is the same,
36, 37. How much thus far has been done with the food ? The next process ?
Give the first way.
38. How is absorption effected in another way? Describe it. Name of the
lacteals ? Thoracic duct ?
DIGESTION.
97
E,
which is the right side of the heart. The lacteals receive
their name from their milky-white appearance. After a
meal containing a por-
tion of fat, they are
then distended with
chyle, which they are
Specially adapted to
receive : at other times
they are hardly dis-
cernible. The lacteals
all unite to form one
tube, the thoracic duct,
which passes upward
through the tliorax, or
chest, and empties into
a large vein, situated
just beneath the left
collar-bone.
39. The Absorb-
ents, The lacteals
belong to a class of
vessels known as absorbents, or lymphatics, which ram-
ify in nearly all parts of the body, except the brain and
spinal cord. The fluid which circulates through the lym-
phatics of the limbs, and all the organs not concerned in
digestion, is called lympli. This fluid is clear and color-
less, like water, and thus diifers from the milky chyle
which the lacteals carry after digestion : it consists chiefly
of the watery part of the blood, which was not required by
the tissues, and is returned to the blood by the absorbents
or lymphatics. (Read Note 4.)
40. Circumstances affecting Digestion. What
length of time is required for the digestion of food ? From
observations made, in the case of St. Martin, the Canadian
FIG. 24. THE LACTEALS.
A, Small Intestine. B, Lacteals.
C, Thoracic Duct. D, Absorbents.
E, Blood-vessel.
39. The absorbents ? Lymph ? What further of the Ivmph ?
40. What can you state a? to the time required lor digestion?
98 DIGESTION.
already referred to, it has been ascertained that, at the end
of two hours after a meal, the stomach is ordinarily empty.
How much time is needed to complete the digestion of
food, within the small intestines, is not certain ; but, from
what we have learned respecting their functions, it must
be evident that it largely depends upon the amount of
starch and fat which the food contains.
41. In addition to the preparations which the food
undergoes, in cooking, which we have already considered,
many circumstances affect the duration of digestion ; such
as the quality, quantity, and temperature of the food ; the
condition of the mind and body ; sleep, exercise, and habit.
Fresh food, except new bread and the flesh of animals
recently slain, is more rapidly digested than that which is
stale ; and animal food more rapidly than that from the
vegetable kingdom.
42. Food should not be taken in too concentrated a form,
the action of the stomach, being favored when it is some-
what bulky ; but a large quantity in the stomach often re-
tards digestion. If the white of one egg be given to a dog,
it will be digested in an hour, but if the white of eight
eggs be given it will not disappear in four hours. A wine-
glassful of ice-water causes the temperature of the stomach
to fall thirty degrees ; and it requires a half-hour before it
will recover its natural warmth about a hundred degrees
at which the operations of digestion are best conducted.
A variety of articles, if not too large in amount, is more
easily disposed of than a meal made of a single article;
although a single indigestible article may interfere with
the reduction of articles that are easily digested.
43. Strong emotion, whether of excitement or depression,
checks digestion, as do also a bad temper, anxiety, long
fasting, an cl bodily fatigue. The majority of these condi-
41. Circumstances affecting duration of digestion ? Fresh food ?
42. Food in concentrated form ? A large quantity of food? Experiment on
the dog? Ice-water? Variety of articles ?
43. Strong emotion ? The tongue of the patient ?
DIGESTION. 99
tions rmike the mouth dry, that is, they restrain the flow
of the saliva ; and without doubt they render the stomach
dry also, by preventing the flow of the gastric juice. And,
as a general rule, we may decide, from a parched and coated
tongue, that the condition of the stomach is not very dis-
similar, and that it is unfit for the performance of digestive
labor. This is one of the points which the physician bears
in mind when he examines the tongue of his patient.
44. The practice of eating at short intervals, or " between
meals," as it is called, has its disadvantage, as well as rapid
eating and over-eating, since it robs the stomach of its needed
period of entire rest, and thus overtasks its power. With
the exception of infants and the sick, no persons require
food more frequently than once in four hours. Severe
exercise either directly before or directly after eating retards
digestion ; a period of repose is most favorable to the proper
action of the stomach. The natural inclination to rest
after a hearty meal may be indulged, but should not be
carried to the extent of sleeping ; since in that state the
stomach, as well as the brain and the muscles, seeks re-
lease from labor. (Read Note 6.)
44. Eating between meals ? Severe exercise ? Sleet) after meais l
100 REVIEW QUESTIONS.
QUESTIONS FOR TOPICAL REVIEW.
PAGE
1. What do you understand by nutrition ? 80
2. How is the process of nutrition carried on ? 80
3. What further can you state on the subject ? 80, 81
4. Describe the general plan of digestion 81
5. How is the process of mastication carried on ? 80, 82
6. State what you can in relation to the formation of the teeth 82, 86
7. What, in relation to their arrangement ? 83, 84
8. What, in relation to the process of " shedding ?" 82, 83, 84
9. In relation to the different forms of teeth in different animals ? t5
10. What causes operate to injure or destroy the teeth ? 85, 86
11. What suggestions and directions are given for the preservation of the
teeth? 85,86
12. What do you understand by insalivation ? 80, 86
13. How is the process of insalivation carried on ? 86,, 87, 88
14. Of what importance is the saliva to the process ? 87, 88
15. Of what importance are mastication and insalivation ? 88, 89
16. Describe the consequences of rapid eating 89, 90
17. What becomes of the food directly after it has undergone mastication
and insalivation ? 90
18. Describe the location and formation of the stomach 90, 91, 92
19. Describe the process by which the gastric juice is formed 91
20. What are the properties and uses of the gastric juice ? 92
21. What are the movements of the stomach, and what their uses ? 92, 93
22. What further can you state on the subject ? 93
23. What portions of the food are digested in the stomach ? 93, 9-i
24. What are the first changes of digestion ? 93
25. Describe the location and formation of the stomach 94
26- What further can you state in relation to the stomach ? 94
27. Descri De the process of intestinal digestion 94, 95, 96
28. What, do you understand by absorption ? 80, 96
29. How is the process of absorption effected ? 96, 97
30. What are the lacteals, and of what use are they* 96, 97
31. What length of time is required for the digestion of food ? 97, 9e
32. What circumstances, of food, affect digestion ? 98
33. What circumstances, of emotion, affect digestion? 98, 98
34. What suggestions and directions are given upon the subject of eating
and drinking?... 98,9"
1. The First Step of Question (p. 88, T 17). "The digestive process
begins in the mouth; a:;io:ig civilized people it begins in the plate, or even before.
Undoubtedly mastication is the natural method of mincing meat, and not the least
of its value lies in the fact that it takes time. A man who in eating a tough, and
therefore not very digestible chop, will be slo\v in eating, if he is careful to masti-
cate it well. There will be a long interval between each mouthful, and the stom-
ach, will run no risk of being hastily loaded.
" Now, a hastily-loaded stomach is as bad almost as, or rather is the same thing
as, an overloaded stomach ; and there can be no doubt that artificial mastication
becomes a snare when it leads any one to introduce a large quantity of finely-
minced meat suddenly and rapidly into an unprepared stomach, especially into
the feeble stomach of an invalid, under the idea that, because the meat is so nice-
ly minced and so very tender, it can be no possible burden to that sorely-tried
organ. Natural mastication has, besides, another advantage over the artificial
process, which is perhaps not always recognized. Whenever food enters the mouth,
it gives rise to what is called a flow of saliva. This saliva is secreted by certain
gland?, which pour into the mouth the fluid they strain off from the blood, and
which are excited or stimulated to action by the presence of food in the mouth,
as well as by other causes. Saliva rapidly changes starch into .sugar, and sugar
is pre-eminently a soluble body, passing with the greatest ease from the alimentary
canal into the blord." People's Magazine (London).
2. The Digestibility of Solid Foods (p. 93, 1 28). The accompanying
table shows some of the results obtained from the experiments of Dr. Beaumont
upon the stomach of Alexis St. Martin. It will surprise many to find that vegeta-
ble foods they are placed in the lattor part of the table require, as a rule, as
much time for digestion as animal food.
Food.
M^de of
Cooking.
quired for
digestion.
n. m.
..5 15
, .4 15
Pork ................... roasted.
Canilage ............... boiled . .
Ducks ................. roasted ..... 4
Fowls .................. do ...... 4
Do ................... boiled ..... 4
Beef ................... fried ....... 4
Eggs ................... do ....... 3 30
Do .................. hard boiled.3 30
Cheese ............................ 3 30
Oysters ............... shewed ..... 330
Mutton ................ roasted ..... 3 15
boik-d ...... 3
roasted ..... 3
boiled ...... 2 45
fricas-eed..2 45
broiled ..... 2 30
roasted ..... 2 30
Do
Beef
Do
Chicken
Lamb
Pig (suckling)
Goose
do
Gelatin boiled..
Turkey do. ...
Eggs roasted.
Cod Fish (cured, dry). . . boiled ...
Ox Liver broiled..
Venison Steak broiled. .
, 2 30
,.2 30
.2 25
.2 15
,.2
,.2
.1 30
Time re-
Food. Mode of quired for
F00d - Cocking. diction.
h. in.
Salmon Trout boiled 1 30
'4gs (whipped) raw
i Tripe (soused)
Pig's feet (soused).
Cabbage
Beetroot
Turnips
Potatoes do.
Wheaten bread baked.
Carrot boiled.
Indian Corn bread.
Do. cake.
Applo-dumpling. . .
Potatoes
Do
Parsnips
Sponge cake
Beans
Apples (sour)
Barley
Tapioca
Sago
boiled
do
boiled
do
do
baked. . .
do. ..
boiled...
baked...
roasted. .
boiled...
baked. ..
boiled...
ra \v
boiled...
do. ,
.1
..1
.4
..345
,.3 30
,.3 30
..3 30
.3 15
.3 15
-.3
..3
, .2 33
..2 30
..2 30
, .2 30
..2 30
..2
..2
,.2
..1 45
Apples (sweet) raw 1 30
Rice boiled 1
3. Tight Clothing interferes with Digestion (p. 95, t 33). " On
one wet winter's day at Florence, some years ago, I had boon spending the mornin
m the studio of a sculptor of world- wide reputation. We had discussed the perfe*
NOTES.
tions of female beauty, and I felt that I was sitting at the feet of a thinker, as well as
an 'elegansformarum spectator.'' In the evening we met again at a hospitable palaz-
zo, and, under cover of the waltz, from a quiet corner of observation we saw
whirling by in the flesh, much that we had been thinking of in the marble and
the clay, and our eyes could not but follow one particular face, famous for the
assistance its great natural beauty received from art. 'Face ' I said, but the mind
of Hiram Powers was penetrating deeper, for he exclaimed, after a short silence:
'That is all very well, but I want to know where Lady puts her liver!'
Where, indeed! for, calculating the circumference of the waist by the eye, allow-
ing a minimum thickness for the walls of the chest, an area for the spine, oesopha-
gus, and great blood vessels, the section of the waist seemed to admit of no room
for anything else. In such a body the liver must be squeezed down into the abdo-
men, stick into its hollow neighbors, and infringe upon all the organs. The organ,
which suffers most is the unresisting stomach, which is dragged and pushed out
of all form during the continuance of this packing process." Dr. T. K. Cham-
bers on the Indigestions.
4. Absorption of the Lacteals (p. 97, 1 39). The force by which the
milky fluid moves upward through the lacteals is very considerable. This has
been proved by the distension of the whole system of vessels, including the
thoracic duct, even to the occurrence of rupture, when that duct has been tied in
an animal a short time before it has been fed. The movement of the fluid thus,
in some measure, resembles absorption by the spongioles at the extremities of the
roots of trees, and the continuous rising of the sap. The thoracic duct may
become diseased ; and a serious derangement of nutrition takes place. In the case
of an unfortunate person, who was some years ago exhibited as a curiosity under
the name of the 'living skeleton,' was illustrated the slow starvation that may
thus be produced. Although he was able to take food in abundant supply, he was
not nourished by it. Finally he died, and an examination of hit* body disclosed
the fact that the thoracic duct had been obstructed by disease, and absorption by
the lacteals was prevented.
5. Work or Exertion (p. 99, t 44). "The best time to make great exertion
is about two hours after a meal. It is not a good time before breakfast, although
moderate work may be then performed ; and those who go to work before break-
fast should first take a cup of hot milk, tea, or coffee, or other simple food. The
body is weakest before breakfast.
" Violent or rapid exertion made by children, and also by stout or aged people,
often injures, and sometimes causes disease of the heart, when the same taken in
the ordinary way would do no harm. Rapidly running up-stairs, or to meet a train,
sometimes causes death. Hence, whilst exercise is of the utmost importance to
health, it should be taken in a regulated and rational manner, and particularly by
those who have parsed the period of youth. But disease of the heart, even in youth,
may often be traced to indiscretion in this particular, wht-ther in rowing, running,
or jumping." Edward Smith on Health.
6. Indigestible Matters (p. 94, ^ 30). " Children sometime? swallow coins,
buttons, etc., and so cause great alarm. There is little real ground for apprehension
under these circumstances, unless the coins are bronze. If the latter, there is
some cause for fear that copper poisoning will en-ue, and the ready passage of the
coin is desirable. This is best effected by meals of figs or pudding, in which the
coins are imbedded and so passed harmlessly. As to bulk, whatever will go into
the stomach will rass the various straits and emerge again." Fothtrgitt.
CIRCULATION OF THE BLOOD.
I Heart,Luhs. Arteries &Vein. s.i
THE CIRCULATION 10V
CHAPTER VII.
THE CIRCULATION.
TJie Blood Its Plasma and Corpuscles Coagulation of the Blood TJie
Uses of the Blood Transfusion Change of Color The Organs of
the Circulation TJie Heart, Arteries, and Veins TJie Cavities
and Valves of the Heart Its Vital Energy Passage of the Blood
through tJie Heart The Frequency and Activity of its Movements
The Pulse The SpygmograpJiTJie Capillary Blood-vessels The
Hate of the Circulation Assimilation Injuries to the Blood-vessels.
1. The Blood. Every living organism of the higher
sort, whether animal or vegetable, requires for the main-
tenance of life and activity, a circulatory fluid, by which
nutriment is distributed to all its parts. In plants, this
fluid is the sap; in insects, it is a watery and colorless
blood; in reptiles and fishes, it is red but cold blood:
while in the nobler animals and man, it is the red and
warm blood.
2. The blood is the most important, as it is the most
ibundant, fluid of the body; and upon its presence, under
certain definite conditions, life depends. On this account
it is frequently, and very properly, termed "the vital
fluid." The importance of the blood, as essential to life,
was recognized in the earliest writings. In the narration
of the death of the murdered Abel, it is written, " the voice
of his blood crieth from the ground." In the Mosaic law,
proclaimed over thirty centuries ago, the Israelites were
forbidden to eat food that contained blood, for the reason
that "the life of the flesh is in the blood." With the
exception of a few tissues, such as the hair, the nails,
and the cornea of the eye, blood everywhere pervades the
body, as may be proven by puncturing any part with a
1 . What is required by every living organism ? In plants ? Insects ? Reptiles ?
Man?
2. Importance and abundance of blood? Dependence of life ? Abel ? Mosaic
law ? In what part of the body is blood not found ? Quantity of blood in the body ?
102
THE CIRCULATION.
needle. The total quantity of blood in the body is esti*
mated at about one-eighth of its weight, or eighteen
pounds.
3. The color of the blood, in man and the higher ani-
mals, as is well known, is red ; but it varies from a bright
scarlet to a dark purple, according to the part whence it is
taken. " Blood is thicker than water," as the adage truly
states, and has a glutinous quality. It has a faint odor,
resembling that peculiar to the animal from which it is
taken.
4. When examined under the microscope, the blood no
longer appears a simple fluid, and its color is no longer red.
It is then seen to be made up of two distinct parts: first,
a clear, colorless fluid, called the plasma; and secondly,
of a multitude of minute solid bodies, or corpuscles,
that float in the watery plasma. The plasma, or nutritive
liquid, is composed of water richly charged with materials
derived from the food, viz., ' albumen, which gives it
smoothness and swift motion; fibrin; certain fats; traces
of sugar ; and various salts.
r 5. The Blood Corpus*
cles. In man, these remark"
able "little bodies," as the
word corpuscles signifies, arc
of a yellow color, but by theii
vast numbers impart a red
hue to the blood. They are
very small, having a diameter
of about -^Vfr f an inch, and
being one-fourth of that frac-
tion in thickness; so that if
3,500 of them were placed in
line, side by side, they would only extend one inch ; or, if
FIG. 25. THE BLOOD CORPUSCLES.
3. Color of blood ? Its consistence ? Odor ?
4. What is* stated of the blood as viewed under the microscope ?
5. State what you can oi the liltlo bodies called corpuscles*.
THE CIRCULATION"
103
piled one above another, it would take at least 14,000 of
them to stand an inch high. Although so small in size,
they are very regular in form. As seen under the micro-
scope, they are not globular or spherical, but flat, circular,
and disc-like, with central depressions on each side, some-
what like a pearl button that has not been perforated. In
freshly-drawn blood they show a disposition to arrange
themselves in little rolls like coins (Fig. 25).
6. The size and shape of the blood corpuscles var} in
different animals, so that it is possible to discriminate be-
tween those of man and the lower
animals (Fig. 26). This is a point of
considerable practical importance. ^'-^
For example, it is sometimes desir-
able to decide in a court of justice ^
the source, whether from man or an
inferior animal, of blood stains upon
the clothing of an accused person, or
upon some deadly weapon. This may
be done by a microscopical examina-
tion of a minute portion of the dried
stain, previously refreshed by means
of gum-water. Certain celebrated
cases are recorded in which the guilt
of criminals has been established, and
they have been condemned and pun- a ovaicorpu.cie.ofafowi.
ished upon the evidence which sci-
FIG. 26.
pnr>r rpnrlprprl nn fVii incrlp -nm'nr The five email ones at the
ence rendered on tnis single point, uppei . part of the flirliref rep .
the detecting of the human from
other blood.
7. The character of the blood of dead, extinct, and even
fossil animals, such as the mastodon, has been ascertained
by obtaining and examining traces of it which had been
shut up, perhaps for ages, in the circulatory canals of bone.
A means of detecting blood in minute quantities is found
6. The size and shape of the corpuscles? Why is the fact important ?
7. Tin character of the blood of dead animals f Meana of detecting such blood
r
104 THE CIRCULATION.
in the spectroscope, the same instrument by \vnich the
constitution of the heavenly bodies has been studied. If
a solution containing not more than one-thousandth part
of a grain of the coloring matter of the corpuscle, be ex-
amined, this instrument will detect it.
8. The corpuscles, just described, are known as the red
blood corpuscles. Besides these, and floating along in the
same plasma, are the white corpuscles. These are fewer
in number, but larger and globular in form. They are
colorless, and their motion is less rapid than that of the
other variety. The total number of both varieties of these
little bodies in the blood is enormous. It is calculated that
in a cubic inch of that fluid there are eighty-three mil-
lions, and at least five hundred times that number in f he
whole body. (Read Note i.)
9. Coagulation. The blood, in its natural condit. n
Nin the body, remains perfectly fluid; but, within a fe r
minutes after its removal from its proper vessels, whether
by accident or design, a change takes place. It begins to
coagulate, or assume a semi-solid consistence. If allowed
to stand, after several hours it separates into two distinct
parts, one of them being a dark red jelly, the coagulum,
or clot, which is heavy and sinks: and the other, a clear,
straw-colored liquid, called serum, which covers the clot.
This change is dependent upon the presence in the blood
of fibrin, which possesses the property of solidifying under
certain circumstances; one of these circumstances being
when the blood is separated from living tissues. The color
of the clot is due to the entanglement of the corpuscles
with the fibrin.
10. In this law of the coagulation of the blood is our
r safeguard against death by haemorrhage, or against undue
loss of blood. If coagulation were impossible, the slight-
8, White corpuscles ? Total number of corpuscle? in the body ">.
9. The blood in its natural condition in the body ": Describe the process by
which the coagulation of blood takes place; ?
10. If coagulation were impossible ? How is it iu fact ?
THE CIRCULATION. 105
est injury in drawing blood would prove fatal. Whereas
now, in vastly the larger proportion of cases, bleeding
ceases spontaneously, because the blood, as it coagulates,
stops the mouths of the injured blood-vessels. In another
class of cases, where larger vessels are cut or torn, it is
simply necessary to close them by a temporary pressure ;
for in a few minutes the clot will form and seal them up.
In still more serious cases, where the blood-vessel is of
large size, the surgeon is obliged to tie a " ligature" about
it, and thus prevent the force of the blood-current from
washing away the clots, which, forming within and around
the vessel, would close it effectually.
K 11. It is worthy of remark that this peculiarity is early
implanted in the blood, even before birth, and in advance
of any existing necessity for it; thus anticipating and
guarding against danger. But this is not all. Of most
of the inferior animals, which, as compared with man, are
quite helpless, the blood coagulates more rapidly, and in
the case of the birds, almost instantly. The relative
composition of fluid and coagulated blood may be thus
^resented:
Fluid Blood. Coagulated Blood.
Plasma,... Serum Serum
--Fibrin---....
Corpuscles Corpuscles l':::-:-Clot.
, 12. The Uses of the Blood. The blood is the great
/provider and purifier of the body. It both carries new
materials to all the tissues, and removes the worn out par-
ticles of matter. This is effected by the plasma. It both
conveys oxygen and removes carbonic acid. This is done
through the corpuscles. Some singular experiments have
11. What is worthy of remark ? Coagulation of the blood of inferior animals f
Of the blood of bird^ ?
12. The blood, as a provider and purifier? What uses does the blood sub-
serve ? Experiments ? Transfusion ?
106 THE CIRCULATION.
been tried to illustrate the life-giving power of the blood.
An animal that has bled so freely as to be at the point of
dying, is promptly brought back to life by an operation
called transfusion, by which fresh blood from a living
animal is injected into the blood-vessels of his body.
~ 13. It is related that a dog, deaf and feeble from age,
f had hearing and activity restored to him by the introduc-
tion into his veins of blood taken from a young dog ; and,
that a horse, twenty-six years old, having received the blood
of four lambs acquired new vigor. And further, that a dog,
just dead from an acute disease, was so far revived by trans-
fusion, as to be able to stand and make a few movements.
14. Transfusion has been practised upon man. At one
T time, shortly after Harvey's discovery of the " Circulation
of the Blood," it became quite a fashionable remedy, it
being thought possible by it to cure all forms of disease,
and even to make the old young again. But these claims
were soon found extravagant, and many unhappy accidents
occurred in its practice ; so that being forbidden by govern-
ment and interdicted by the Pope, it rapidly fell into
disuse. At the present time, however, it is sometimes re-
sorted to in extreme cases, when there has been a great
and rapid loss of blood ; and there are upon record several
instances where, other means having failed, life has been
restored or prolonged by the operation of transfusion.
15. This reviving power of the blood seems to reside in
the corpuscles; for transfusion, when attempted to be per-
formed with the serum alone, has, in every case, proved fruit-
less. Now, though so much depends upon the blood and
its corpuscles, it is a mistake to suppose that in them alone
is the seat of life, or that they are, in an exclusive manner,
alive. All the organs and parts of the body are mutually
dependent one upon the other; and the complete usefulness
13. The case of the deaf and fei-bli 1 dog? Horse? Dead dog ?
14. Transfusion, as a fashionable remedy ? What further of transfusion ?
15. The seat of the reviving power of the blood ? What further is related ?
THE CIRCULATION. !(/?
of the blood, or of any other part, flows out of the har-
monious action of all the parts.
r 16. Change of Color. The blood undergoes a variety
of changes in its journey through the system. As it visits
the different organs it both gives out and takes up mate-
rials. In one place it is enriched, in another it is impover-
ished. By reason of these alterations in its composition,
the blood also changes its color. In one part of the body
it is bright red, or arterial ; in another it is dark blue, or
venous. In the former case it is pure and fit for the sup-
port of the tissues ; in the latter, it is impure and charged
with effete materials. (The details of the change from
dark to bright will be given in the chapter on Respira-
tion.) (Read Note 2.)
r 17. Circulation. The blood is in constant motion
during life. From the heart, as a centre, a current is
always setting toward the different organs; and from these
organs a current is constantly returning to the heart. In
this way a ceaseless circular movement is kept up, which is
called the Circulation of the Blood. This stream of the
vital fluid is confined to certain fixed channels, the blood-
vessels. Those branching from the heart are the arteries;
those converging to it are the veins. The true course of
the blood was unknown before the beginning of the seven'
teenth century. In 1619 it was discovered by the illustri-
ous William Harvey. Like many other great discoverers,
he suffered persecution and loss, but unlike some of them,
he was fortunate enough to conquer and survive opposi-
tion. He lived long enough to see his discovery universally
accepted, and himself honored as a benefactor of mankind.
18. The Heart. The heart is the central engine of
the circulation. In this wonderful little organ, hardly
'
16. Changes in the blood ? What further is slater! ?
17. Motion of the blood? What is meant by the circulation of the blood?
How confined ? Discovery made by Harvey ?
18. Office of the heart ? Location of the heart ? Its beat? Its shape? Pro-
tection to the heart ? What else is said in relation to the heart ?
108 THE CIRCULATION.
. 27. THE ORGANS op CIRCULATION.
THE CIRCULATION".
109
larger than a man's fist, resides that sleepless force by
which, during the whole of life, the current of the blood
is kept in motion.
It is placed in the
middle and front
part of the chest,
inclining to the left
side. The heart-
beat may be felt and
heard between the
fifth and sixth ribs,
near the breast-bone.
Theshapeofthehenrt
is conical, with the
apex or point down-
ward and . in front.
The base, which is
upward, is attached
so as to hold it se-
curely in its place,
while the apex is
freely moveable. In
order that loss of
power from friction
may be obviated, the
heart is enclosed between two layers of serous membrane,
which forms a kind of sac. This membrane is as smooth
as satin, and itself secretes a fluid in sufficient quantities
to keep it at all times well lubricated. The lining mem-
brane of the heart, likewise, is extremely delicate and
Smooth. (Read Note 3.)
' 19. The Cavities of the Heart. The heart is hol-
low, and so partitioned as to contain four chambers or
cavities; two at the base, known as the auricles, from a
FIG. 28. THE HEART AND LARGE VESSELS.
A, Right Ventricle. D, Left Auricle.
B, Left
C, Right Auricle.
E, Aorta.
F, Pulmonary Artery.
19. Formation of the heart ? Right and left heart ?
TI1E CIRCULATION.
110
/fancied resemblance to the ear of a dog, and two at the
apex or point, called ventricles. An auricle and a ventricle
on the same side,
communicate with
each other, but there
is no opening from
side to side. It is
customary to regard
the heart as a double
organ, and to speak
of its division into
the right and left
heart. For while
both halves act to-
gether in point of
time, each half sus-
tains an entirely dis-
tinct portion of the
labor of the circu-
lation. Thus, the
right heart always
carries the dark or
venous blood, and the left always circulates the bright or
arterial blood.
20. If we examine the heart, we at once notice that
I though its various chambers have about the same capacity,
the walls of the ventricles are thicker and stronger than
those of the auricles. This is a wise provision, for it is by
the powerful action of the former that the blood is forced
to the most remote regions of the body. The auricles, on
the contrary, need much less power, for they simply dis-
charge their contents into the cavities of the heart near at
hand and below them into the ventricles.
FIG. 29. SECTION OP THE HEART.
A, Right Ventricle.
B, Left
C, Right Auricle.
D, Left Auricle.
E, F, Inlets to the Ventricles.
G, Pulmonary Artery.
H, Aorta.
20. Capacity of the chambers of the heart? What wise provision is men-
tioned ? The auricles ?
THE CIRCULATION". Ill
* 21. Action of the Heart. The substance of the
heart is of a deep red color, and its fibres resemble those
of the voluntary muscles by which we move our bodies.
But the heart's movements are entirely involuntary. The
advantage of this is evident; for if it depended upon
us to will each movement, our entire attention would be
thus engaged, and we would find no time for study, pleas-
ure, or even sleep. The action of the heart consists in
alternate contractions and dilatations. During contrac-
tion the walls come forcibly together, and thus drive out
the blood. In dilatation, they expand and receive a renewed
supply. These movements are called systole and diastole.
The latter may be called the heart's period of repose; and
although it lasts only during two-fifths of a heart-beat, or
about a third of a second, yet during the day it amounts
to more than nine hours of total rest.
' 22. A remarkable property of tne tissue of the heart is
its intense vitality. For while it is more constantly active
than any other organ of the body, it is the last to part
with its vital energy. This is especially interesting in
view of the fact that after life is apparently extinguished,
as from drowning, or poisoning by chloroform, there yet
lingers a spark of vitality in the heart, which, by contin-
ued effort, may be fanned into a flame so as to revivify the
whole body. In cold-blooded animals this irritability of
the heart is especially remarkable. The heart of a turtle
will pulsate, and the blood circulate for a week after its
head lias been cut off; and the heart will throb regularly
many hours after being cut out from the creature's chest.
The heart of a frog or serpent, separated entirely from the
body, will contract at the end of ten or twelve hours: that
of an alligator has been known to beat twenty-eight hours
after the death of the animal.
21. Substance of the heart,? Its fibres? Its movements? The advantage
of such movements? Action of the heart? It* period of ivpose ?
22. Remarkable property of the tissue of the heart ? How shown ? How in-
teresting ? In cold-blooded animals ? Heart of a turtle ? Of a frog ? Alligator?
112 THE CIRCULATION.
23. Passage of the Blood through the Heart.
Let us now trace the course of the blood through the
several cavities of the heart. In the first place, the venous
blood, rendered dark and impure by contact with the
changing tissues of the body, returns to the right heart
by the veins. It enters and fills the right auricle during
its dilatation : the auricle then contracts and fills the right
ventricle. Almost instantly, the ventricle contracts forcibly
and hurries the blood along the great artery of the lungs,
to be purified in those organs. Secondly, having completed
the circuit of the lungs, the pure and bright arterial blood
enters the left auricle. This now contracts and fills the left
ventricle, which cavity, in its turn, contracts and sends the
blood forth on its journey again through the system. This
general direction from right to left is the uniform and un-
deviating course of heart-currents.
r 24. The mechanism which enforces and regulates it, is
vis simple as it is beautiful. Each ventricle has two open-
ings, an inlet and an outlet, each of which is guarded by
strong curtains, or valves. These valves open freely to
admit the blood entering from the right, but close inflex-
ibly against its return. Thus, when the auricle contracts,
the inlet valve opens ; but as soon as the ventricle begins
to contract, it closes promptly. The contents are then, so
to speak, cornered, and have but one avenue of escape,
that through the outlet valve into the arteries beyond. As
soon as the ventricle begins to dilate again, this valve
shuts tightly and obstructs the passage. The closing of
these valves occasions the two heart-sounds, which we hear
at the front of the chest.
f 25. Frequency of the Heart's Action. The alter-
nation of contraction and dilation constitutes the heart-
23. Course of the blood through the heart ? Course of heart-currents ?
24. Openings of the ventricles ? How guarded ? How do the valves operate ?
The consequence ? Heart-sounds ?
25. Heart-beats? The heart as a susceptible organ? Heat, exercise, etc,,?
Posture f
THE CIRCULATION. 113
beats. These follow each other not only with great
regularity, but with great rapidity. The average number
in an adult man is about seventy-two in a minute. But
the heart is a susceptible organ, and many circumstances
affect its rate of action. Heat, exercise, and food will
increase its action, as cold, fasting, and sleep will decrease
it. Posture, too, has a curious influence; for if while sit-
ting, the beats of the heart number seventy-one; standing
erect will increase them to eighty-one, and lying down
will lower them to sixty-six.
26. The modifying influence of mental emotions is very
powerful. Sudden excitement of feeling will cause the
heart to palpitate, or throb violently. Depressing emotions
sometimes temporarily interrupt its movements, and the
person faints in consequence. Excessive joy, grief, or fear,
lias occasionally suspended the heart's action entirely, and
thus caused death. The rate of the heart-beat may be
naturally above or below seventy-two. Thus it is stated
that the pulse of the savage is always slower than that of
the civilized man. Bonaparte and Wellington were very
much alike in their heart's pulsations, which were less than
fifty in the case of each.
/S 27. Activity of the Heart. The average number of
heart-beats during a lifetime may be considered as at the
rate of seventy-two per minute, although this estimate is
probably low ; for during several years of early life the rate
is above one hundred a minute. In one hour, then, the
heart pulsates four thousand times ; in a day, one hundred
thousand times; and in a year, nearly thirty-eight million
times. If we compute the number during a lifetime, thirty-
nine years being the present average longevity of civilized
mankind, we obtain as the vast aggregate, fourteen hun-
dred millions of pulsations. (Read Note 5.)
26. Mental emotion?? . Sudden excitement? Excessive joy ? The heart-beat
rate ? Bonaparte and Wellington ?
2*?. Average number of heart-bea:s? In one hour ? Year? Lifetime?
114 THE CIRCULATION.
28. Again, if we estimate the amount of blood expelled
by each contraction of the ventricles, at four ounces, tnen
the weight of the blood moved during one minute will
amount to eighteen pounds. In a day it will be about
twelve tons; in a year, four thousand tons; and in the
course of a lifetime, over one hundred and fifty thousand
tons. These large figures indicate, in some measure, the
immense labor necessary to carry on the interior and vital
operations of our bodies. In this connection, we call to
mind the fanciful theories of the ancients in reference to
the uses of the heart. They regarded it as the abode of
the soul, and the source of the nobler emotions bravery,
generosity, mercy, and love. The words courage and
cordiality are derived from a Latin word signifying heart.
Many other words and phrases, as hearty, heart-felt, to learn
by heart, and large-hearted, show how tenaciously these ex-
ploded opinions have fastened themselves upon our language.
29. At the present time the tendency is to ascribe purely
mechanical functions to the heart. This view, like the
older one, is inadequate; for it expresses only a small part
of our knowledge of this organ. The heart is unlike a
simple machine, because its motive power is not applied
from without, but resides in its own substance. Moreover,
it repairs its own waste, it lubricates its own action, and it
modifies its movements according to the varying needs of
the system. It is more than a mere force-pump, just as
the stomach is something more than a crucible, and the
eye something more than an optical instrument.
* 30. The Arteries. The tube-like canals which carry
the blood away from the heart are the arteries. Their
walls are made of tough, fibrous materials, so that they
sustain the mighty impulse of the heart, and are not rup-
tured. In common with the heart, the arteries huve a del-
2S. Amount of blood expelled ? Theories of the ancient* ?
29. The tendency at, the present tim ; ? Whv is this view inadequate ?
3 What are the arteries? Their walU ? Their membrane ?
THE CIRCULATION. 115
icately smooth lining membrane. They are also elastic,
and thus re-enforce the action of the heart: they always
remain open when cut across, and after death are usually
found empty.
/^ 31. The early anatomists observed this phenomenon,
and supposing that the same condition existed during life,
came to the conclusion that these tubes were designed to
act as air-vessels, hence the name artery, from a Greek
word which signifies containing air. This circumstance
affords us an illustration of the confused notions of the
ancients in reference to the internal operations of the
body. Cicero speaks of the arteries as "conveying the
breath to all parts of the body,"
32. The arterial system springs from the heart by a
single trunk, like a minute and hollow tree, with number-
less branches. As these branches leave the heart they
divide and subdivide, continually growing smaller and
smaller, until they can no longer be traced with the
naked eye. If, then, we continue the examination by the
aid of a microscope, we see these small branches sending
off still smaller ones, until all the organs of the body are
penetrated by arteries.
f 33. The Pulse. With each contraction of the left
heart, the impulse causes a wave-like motion to traverse
the entire arterial system. If the arteries were exposed to
view, we might see successive undulations speeding from
the heart to the smallest of the branches, in about one-
sixth part of a second. The general course of the arteries
is as far as possible from the surface. This arrangement
is certainly wise, as it renders them less liable to injury,
the wounding of an artery being especially dangerous. It
also protects the arteries from external and unequal pres-
sure, by which the force of the heart would be counter-
3 1 . Early anatomists ? The service of the illustration ?
32. The arterial system ? The branches and Rib-branches of the arteries ?
33. Successive undulations from the heart ? (' on n-e of the arteries? Protec
tion of the arteri'.-s * General locution of !,h" ai-tciics 5*
THE CIRCULATION.
acted and wasted. Accordingly, we generally find these
vessels hugging close to the bones, or hiding behind the
muscles and within the cavities of the body.
34. In a few situations, however, the arteries lie near the
surface ; and if we apply the finger to any of these parts,
we will distinctly feel the movement described, taking place
in harmony with the heart-beat. This is part of the wave-
motion just mentioned, and is known as the pulse. All
are more familiar with the pulse at the wrist, in the radial
artery ; but the pulse is not peculiar to that position, for it
may be felt in the carotid of the neck, in the temporal at
the temple, and elsewhere, especially near the joints.
35. Since the heart-beat makes the pulse, whatevei
aifects the former aifects the latter also. Accordingly, the
pulse is a good index of the state of the health, so far aej
the health depends upon the action of the heart. It in-
forms the physician of the condition of the circulation in
four particulars: its rate, regularity, force, and fullness;
and nearly every disease modifies in some respect the con-
dition of the pulse. A very ingenious instrument, known
as the sphygmograph, or pulse-writer, has recently been
invented, by the aid of which the pulse is made to write
upon paper its own signature, or rather to sketch its own
nrofile. This instrument shows with great accuracy the
30. THE FORM OF THE PULSE.
difference between the pulses of health and those of disease.
In Fig. 30 is traced the form of the pulse in health, which
should be read from left to right. That part of the trace
3 1. Where do the arteries lie ? If we apply the finger ? Pulse ? Where felt ?
35. The: pulse as an index V Of what does it inform the physician ? Instrument
tor recording pulsation '
THE CIRCULATION. 117
which is nearly perpendicular coincides with the contrac-
tion of the ventricles; while the wavy portion marks their
dilatation.
A 36. The Veins. The vessels which convey the blood
' on its return to the heart are the veins. They begin in
the several organs of the body, and at first are extremely
small; but uniting together as they advance, they con-
stantly increase in size, reminding us of the way in which
the fine rootlets of the plant join together to form the
large roots, or of the rills and rivulets that flow together
to form the large streams and rivers. In structure, the
veins resemble the arteries, but their walls are compara-
tively inelastic. They are more numerous, and commu-
nicate with each other freely in their course, by means of
interlacing branches.
^ 37. But the chief point of distinction is in the presence
of the valves in the veins. These are little folds of mem-
brane, disposed in such a way, that
they only open to receive blood
flowing toward the heart, and close
against a current in the opposite
direction. Their position in the
veins on the back of the hand may
be readily observed, if we first ob- pra> 31 _ THE VALVBS op THE
struct the return of blood by a cord VEINS.
tied around the forearm or wrist. In a few minutes the
veins will appear swollen, and upon them will be seen
certain prominences, about an inch apart. These latter
indicate the location of the valves, or, rather, they show
that the vessels in front of the valves are distended by the
blood, which cannot force a passage back through them.
38. This simple experiment proves that the true direction
of the venous blood is toward the heart. That the color
36. What are the veinf ? How do they form ? What do they resemble ?
37. Valves in the veins? What are they? Their position ? Experiment with
the cord ?
38. What will be proved by the experiment ? What inference is drawn ?
118 THE CIRCULATION.
F
of the blood is dark, will be evident, if we compare tLe
hand thus bound by a cord with the hand not so bound
It also proves that the veins lie superficially, while the
arteries are beneath the muscles, well protected from pres-
sure ; and that free communication exists from one vein to
another. If now we test the temperature of the constricted
member by means of a thermometer, we will find that it is
colder than natural, although the amount of blood is*
larger than usual. From this fact we infer, that whatever
impedes the venous circulation tends to diminish vitality ;
and hence, articles of clothing or constrained postures,
that confine the body or limbs, and hinder the circulation
of the blood, are to be avoided as injurious to the health.
V 39. The Capillaries. A third set of vessels completes
the list of the organs of the circulation, namely, the capil-
lary vessels, so called (from the Latin word capillaris,
hair-like), because of their extreme fineness. They are,
however, smaller than any hair, having a diameter of about
yjsVtf f an inch, and can only be observed by the use of the
microscope. These vessels may be regarded as the connect-
ing link between the last of the arteries and the first of
the veins. The existence of these vessels was unknown to
Harvey, and was the one step wanting to complete his
great work. The capillaries were not discovered until
1661, a short time after the invention of the microscope.
40. The circulation of the blood, as seen under the
microscope, in the transparent web of a frog's foot, is a
spectacle of rare beauty, possessing more than ordinary
interest, when we consider that something very similar
is taking place in our own bodies, on a most magnificent
scale. It is like opening a secret page in the history of
our own frames. We there see distinctly the three classes
of vessels with their moving contents ; first, the artery,
39. Capillaries? How regarded ? Harvey?
40. The circulation of the blood in the web of a frogV foot? Descrioe it
How irc-neral 1^ tin- existence of the tissues ?
THE CIRCULATION-.
119
with its torrent of blood rushing down from the heart,
secondly, the vein, with its slow, steady stream flowing in
the opposite direction; and between them lies the network
of capillaries, so fine that the corpuscles can only pass
through "in single file." The current has h^re an uncer-
tain or swaying motion, hurrying first in one direction, then
hesitating, and then turning back in the opposite direction,
FIG. 32. WEB op A FROG'S FOOT,
slightly magnified.
FIG 33. MARGIN OF FROG'S W
magnified 30 diameters.
and sometimes the capillaries contract so as to be entirely
empty. Certain of the tissues are destitute of capillaries ;
such are cartilage, hair, and a few others on the exterior of
the body. In all other structures, networks of these vessels
are spread out in countless numbers : so abundant is the
supply, that it is almost impossible to puncture any part
with the point of a needle without lacerating tens, or even
hundreds of these vessels. (Read Note 5.)
41. The capillaries are elastic, and may so expand as to
produce an effect visible to the naked eye. If a grain of
sand, or some other foreign particle, lodge in the eye, it will
become irritated, and in a short time the white of the eye
will be "blood-shot." This appearance is due to an in-
41.- Elasticity of the capillaries? Grain of sand in the eye!
cases ?
Blush ? Other
THE CIRCULATION.
crease in the size of these vessels. A blush is another exam-
ple of this, but the excitement comes through the nervous
system, and the cause is some transient emotion, either of
pleasure or pain. Another example is sometimes seen in
purplish faces of men addicted to drinking brandy ; in
them the condition is a congestion of the capillary circula-
tion, and is permanent, the vessels having lost their power
of elastic contraction.
42. Rapidity of the Circulation. That the blood
moves with great rapidity is evident from the almost instant
effects of certain poisons, as prussic acid, which act
through the blood. Experiments upon the horse, dog,
and other inferior animals, have been made to measure
its velocity. If a substance, which is capable of a distinct
chemical reaction (as potassium ferrocyanide, or barium
nitrate), be introduced into a vein of a horse on one side,
and blood be taken from a distant vein on the other side,
its presence may be detected at the end of twenty or thirty-
two seconds. In man, the blood moves with greater speed,
and the circuit is completed in twenty-four seconds.
43. What length of time is required for all the blood of
the body to make a complete round of the circulation ?
This question cannot be answered with absolute accuracy,
since the amount of the blood is subject to continual
variations. But, if we assume this to be one-eighth of the
weight of the body, about eighteen pounds, it will be suf-
ficiently correct for our purpose. Now to complete the
circuit, this blood must pass once through the left ventricle,
the capacity of which is two ounces. Accordingly, we find
that, under ordinary circumstances, all the blood makes one
complete rotation every two minutes; passing successively
through the heart, the capillaries of the lungs, the arteries,
the capillaries of the extremities, and through the veins.
42. Show what time is required for a given portion of blood to travel ouce
ii'ounc] the body.
43* Time required for all the blood to circulate completely around?
THE CIRCULATION. 121
44. Assimilation. The crowning act of the circula-
tion, the furnishing of supplies to the different parts of
the body, is effected by means of the capillaries. The or-
gans have been wasted by use ; the blood has been enriched
by the products of digestion. Here, within the meshes of
the capillary network, the needy tissues and the needed
nutriment are brought together. By some mysterious
chemistry, each tissue selects and withdraws from the
blood the materials it requires, and converts them into a
substance like itself. This conversion of lifeless food into
living tissue is called assimilation. The process probably
takes place at all times, but the period especially favorable
for it is during sleep. Then the circulation is slower, and
more regular, and most of the functions are at rest. The
body is then like some trusty ship, which after a long voy-
age is " hauled up for repairs."
45. Injuries to the Blood-vessels. It is important
to be able to discriminate between an artery and a vein, in
the case of a wound, and if we remember the physiology
of the circulation we may readily do so. For, as we have
already seen, haemorrhage from an artery is much more
dangerous than that from a vein. The latter tends to cease
spontaneously after a short time. The arterial blood flows
away from the heart with considerable force, in jets; its
color being bright scarlet. The venous blood flows toward
the heart from that side of the wound furthest from the
heart; its stream being continuous and sluggish; its color
dark. In an injury to an artery, pressure should be made
between the heart and the wound; and in the case of a
vein that persistently bleeds, it should be made upon the
vessel beyond its point of injury. (Read Note 6.)
44. What is meant by assimilation ? What can you say of its use, etc. ? Tim-j *
45. What is stated of the injuries to the blood-vessels ?
122 REVIEW QUESTIONS.
QUESTIONS FOR TOPICAL REVIEW.
TAOB
1. In what organisms is the so-called circulatory fluid found ? 101
2. How is it designated in the different organisms ? 101
3. What can you state of the importance of blood to the body ? 101, 105
4. Of its great abundance, color, and composition ? 101, 102, 107
5. Describe the corpuscles of the human blood 102, 103, 104
6. What is said of them in comparison with those of the lower animals ? 103
7. Of the importance of sometimes detecting human from other blood ? 103
8. What means have we of detecting blood in spots or stains ? 103, 101
9. What is meant by coagulation of the blood ? 104
10. What wisdom is there in the law of the blood's coagulation ? 104 JOS
11. How is this wisdom made manifest ? 105
12. In what cases is the aid of the surgeon required ? 105
13. What are the two great uses of the blood ? 105
14. Through what mediums is the blood provided with new material and re-
lieved of the old material ? 105
15. What do you understand by the operation called transfusion ?. . 106
16. What cases of transfusion are reported of the lower animals ? 106
17. What can you state of transfusion as practised upon man ? 106
18. What further can you say on the subject ? 106, 107
19. What change? take place in the color of the blood in its journey through
the system ? 107
20. State all you can in relation to the circulation of the blood 107
21. All, in relation to the size, shape, and location of the heart 107, 109
22. How is the loss of power in the heart movements obviated ? 109
23. Give a description of the formation of the heart 109, 110, 111
24. What can you state of the ventricles and auricles of the heart ? 110
25. Describe the action of the heart Ill
26. What special vitality does the tissue of the heart possess ? Ill
27. State all you can on the subject Ill
28. Describe the course of the blood through the cavities of the heart 112
29. Describe the mechanism that regulates the heart-currents 112
30. How do you account for the two heart-sounds at the front of the chest ?. . . 112
31. State what you can of the frequency of the heart's action 112, 113
32. Of the activity of the heart 113,114
33. What do you understand by the arteries ? 114, 115
34. State what you can of the arteries and the arterial system 114, 115
35. What do you understand by the pulse ? 115, 116
36. In what part of the body may the pulse be felt ? 116
37. What further can you state of the pulse ? 1x6, 117
8S. What are the veins ? , 117
89. Where do they exist, and how are they formed ? 117
40. Describe the valves of the veins and their uses 117
41. Now give a full description of the construction of the veins 117
42. What further can you siate of the veins ? 117, 118
43. What do you understand by the capillaries ? 118, 119
M. What service do the capillaries perform ? 118, 119, 121
45. Describe the circulation of the blood in the region of the heart 118, 119
46. What can you state of the rapidity of the blood's circulation ? 1 :0
47. Of the process known as assimilation ? 121
48. Of injuries to the blood-vessels ? 121
NOTES.
1. The Blood (p. 104, 18). "You feel quite sure that blood is red, do
yon not ? Well, it is no more red than the water of a stream would be if you were
to fill it with little red fishes. Suppose the fishes to be very, very small, as small
as a grain of sand, and closely crowded together through the whole depth of the
stream, the water would look red, would it not ? And this is the way in which
the blood looks red : only observe one thing; a grain of sand is a mountain in
comparison with the little red bodies that float in the blood, which we have
likened to little fishes. If I were to tell you they measured about the 3200th part
of an inch in diameter, you would not be much the wiser; but if I tell you that
m a single drop of blood, such as might haug on the point of a needle, there are
a million of these bodies, you will perceive that they are both very minute and
very numerous. Not that any one has ever counted them, as you may suppose,
but this is as close an estimate as can be made in view of what is known of their
minute size." M ace's History of a Mouthful of Bread.
2. By Means of the Blood Exercise Benefits the Whole
Body (p. 107, ^ 16). "The employment of the muscles in exercise not only
benefits their especial structure, but it acts on the whole system. When the
muscles are put in action, the capillary blood-vessels with which they are sup-
plied become more rapidly charged with blood, and active changes take place,
not only in the muscles, but iu all the surrounding tissues. The heart is thus
required to supply more blood, and accordingly beats more rapidly in order to
supply the demand. A large quantity of blood is sent through the lungs, and
larger supplies of oxygen are taken in and carried to the various tissues of the
body." The oxygen engenders a large amount of heat, which produces an action
on the skin whereby the increase of heat may be got rid of. By this means the
skin is exorcised, the perspirati m is poured forth, the surf ice is caused to glow
and is kept in health. " Not only are these organs benefited by the increased
circulation of the blood, produced by exercise, but wherever the blood is sent,
changes of a healthful character occur. The brain and the rest of the nervous
system are invigorated ; the stomach has its powers of digestion improved ; and
the liver, pancreas, and other organs perform their functions with more vigor."
Lankester's Manual of Health.
3. A Poet's Summary of the Circulation (p. 109, f 18).
" The smooth, soft air with pulse-like waves
Flows murmuring through its hidden caves,
Whose ptreams of brightning purple rush,
Fired with a new and livelier blush ;
While all their burden of decay
The ebbing current steals away,
And, red with Nature's flame, they start
From the warm fountains of the heart.
No rest that throbbing slave may ask,
Forever quivering o'er his task,
While far and wide a crimson jet
Leaps forth to fill the woven net,
Which, in unnumbered crossing tides,
The flood of burning life divides :
Then, kindling each decaying part,
Creeps back to find the throbbing heart." Dr. 0. W. Holmes.
4. The Heart a Vital machine (p. 113, If 27). "The heart is a machine.
It is an organ constructed of muscular chambers and communicating passages,
and supplied with mechanical contrivances, adapted to guide the stream of blood
NOTES.
puling through it, and to prevent a reflux in ihe backward duvci.oii. i^uos not
this take away wonderfully from the character of fanciful mystery with which
poets and sentimentalists have invested it? The heart that we have always heard
of as the centre of the affections, the home of sensibility, the dwelling-place of
courage, of faith, of hope, and all the rest of the virtues, is, after all, nothing
but an organ to serve for the impulsion of the blood ; a mere force-pump, a
machine. Does not this bring down our ideas, and show that no poetical mys-
tery can escape the searching investigation of the anatomist ? Not at ail.
' For this machine that we carry about with us in our breasts is alive. There,
at its post, at the central point of the circulation, with the soft lobes of the lungs
folded round it like a curtain, it contracts and relaxes and relaxes and contracts,
with a steady and unremitting industry that by itself is something worthy of our
admiration. No other muscle in the body can do this. By some incomprehensible
vitality of its own, it keeps up its rhythmical contractions without the aid of our
will and even without our knowledge. While you are asleep and while you are
awake, from the first moment of your birth, even from before your birth, up to the
present time, it has never for one moment stopped or flagged in its movements,
ibr if it were to do so death would be the result." Dr. J. C. Dalton.
5. Course of the Blood in the Capillaries (p. 119, 1 40). The
phenomena of the capillary circulation are only observable with the aid of the micro-
scope. It was not granted to the discoverer of the circulation to see the blood
moving through the capillaries, and he never knew the exact mode of communi-
cation between the arteries and veins. After it was pretty generally acknowl-
edged that the blood did pass from the arteries to the veins, it was disputed
whether it passed in an intermediate system of vessels, or became diffused in the
substance of the tissues, like a river flowing between numberless little islands, to
be collected by the venous radicles and conveyed to the heart. Accurate micro-
Bcopic investigations have now demonstrated the existence, and given us a clear
idea of the anatomy of the intermediate vessels. In 1661 the celebrated anato-
mist Malpighi first saw the movement of the blood in the capillaries, in the
lungs of a frog. This spectacle has ever since been the delight of the physiolo-
gist. We see the great arterial rivers, in which the blood flows with wonderful
rapidity, branching and subdividing, until the blood is brought to the superb net-
work of fine capillaries, where the corpuscles dart along one by one, the fluid then
being collected by the veins, and carried in great currents to the heart." Flint.
6. The Varieties and Management of Haemorrhage (p. 121, T
45)." Uxmorrhage is the loss of blood either from an artery or a vein. When an
artery is cut, the blood flows in jets corresponding to the beats of the heart and to
the pulse. The jets mark that it is an artery that is wounded ; and indicate that
the pressure must be applied above the haemorrhage, that is, betwixt it and the
heart. On the other hand, the blood returns to the heart by the veins in a steady,
continuous flow. When then the haemorrhage is steady and not in jets, it indi-
cates that the bleeding is from a vein. Here the pressure must be applied to the
limb away from the trunk, or the peripheral end of the limb, or below the bleed-
ing. In addition to this, arerial blood is bright scarlet, while venous biood is
dark and crimson. But these are matters of comparison, and the presence or
absence of jets is the great point of distinction.
" When then a person is wounded, a handkerchief must be bound as tightly as
may be about the limb ; if the haemorrhage is arterial above the point of issue, if
venous below it. Under any circumstances it is best to lay the person down
quietly, especially if the bleeding is from the lower limbs. If they faint, let them
alone in the horizontal posture." FoLkeryill on the Maintenance of Health.
TABLE OF THE PRINCIPAL ARTERIES.
(SEE FIG. OPPOSITE PAGE 101.)
THE HEAD.
Internal Ca-rot'id,) g ^ braln
Verte-bral 9 >
Oph-thal'mic, supplies tlie eye.
1Lin'gual 9 supplies the tongue.
Fa'ci-al 9 " " lower part of face
Tem'po-ral, " " upper part oi
head and face.
THE TRUNK.
The A-or'ta^ arising from the heart, is the main arterial trunk
Cor' o-na-ry 9 supplies the walls of the heart.
Brorichi-al* " " lungs.
In-ter-cos'tals 9 supply the walls of the chest.
Gas'tric, supplies the stomach.
He-pat' id " " liver.
Spleriic, " " spleen.
Re'nal, " " kidney.
Mes-en-ter'ics 9 supply the bowels.
Spi'nal 9 " " spinal cord.
THE UPPER LIMB.
Branches of the Ax-ilJa'ry, supply the shoulder.
" Bra'c7ii-fil 9 " " arm.
Ma'di-al, ) tt forearm and fi ngers
" " Ulnar 9 )
THE LOWER LIMB.
Branches of the Fem'o-ra1 9 supply the hip and thigh,
" " Popliteal 9 \
" " " Tib'i-al 9 ! supply the leg and foot
" Per-oneal )
RESPIRATION. 123
CHAPTER VIII.
RESPIRATION.
The Objects of Respiration The Lungs The Air-Passages The Move-
ments of Respiration Expiration and Inspiration TJie Frequency
of Respiration Capacity of the Lungs The Air we breathe
Changes in the Air from Respiration Changes in the Blood In-
terchange of Oases in the Lungs Comparison between Arterial and
Venous Blood Respiratory Labor Impurities of the Air Dust
Carbonic Acid Effects of Impure Air Nature's Provision for
Purifying the Air Ventilation Animal Heat Spontaneous Com-
bustion.
1. The Object of Respiration. In one set of capil-
laries, or hair-like vessels, the blood is impoverished for the
support of the different members and organs of the body.
In another capillary system the blood is refreshed and again
made fit to sustain life. The former belongs to the greater
or systemic circulation ; the latter to the lesser or pulmo-
nary, so called from pulmo, the lungs, in which organs it
is situated. The blood, as sent from the right side of the
heart to the lungs, is venous, dark, impure, and of a nature
unfit to circulate again through the tissues. But, when
the blood returns from the lungs to the left side of the
heart, it has become arterial, bright, pure, and no longer
hurtful to the tissues. This marvellous purifying change
is effected by means of the very familiar act of respiration,
or breathing.
^ 2. The Lungs. The lungs are the special organs of
respiration. There are two of them, one on each side of
the chest, which cavity they, with the heart, almost wholly
occupy. The lung-substance is soft, elastic, and sponge-
like. Under pressure of_the finger, it crepitates, or crackles,
and floats when thrown into water ; these properties being
1 . Difference between the two sets of capillaries ? Change effected by respira-
tion or breathing?
2. What are the lung?? How many lunge are there? Lung-substance? Its
properties ? The pleura ?
RESPIRATION".
due to the presence of air in the minute air-cells of the
lungs. To facilitate the movements necessary to these
organs, each of them is provided with a double covering of
an exceedingly smooth and delicate membrane, called the
D
FIG. 34. OKGAAS OF THE CHEST.
A, Lungs.
B, Heart.
D, Pulmonary Artery.
E, Trachea.
pleura. One layer of the pleura is attached to the walls
of the chest, and the other to the lungs; and they glide,
one upon the other, with utmost freedom. Like the mem-
brane which envelops the heart, the pleura secretes its own
lubricating fluid, in quantities sufficient to keep it always
moist.
3. The Air-Passages. The lungs communicate with
the external air by means of certain air-tubes, the longest of
3. Communication of the lungs with the external air? Bronchial Uibes 9
RESPIRATION.
1*5
which, the trachea, or windpipe, runs along the front of the
neck (Fig. 34, E, and 35) .With- '
in the chest this tube divides
into two branches, one entering
each lung; these in turn give
rise to numerous branches, or
bronchial tubes, as they are
called, which gradually dimin-
ish in size until they are about
one- twenty-fifth of an inch. in
diameter. Each of these ter-
minates in a cluster of little
pouches, or "air-cells," having
very thin walls, and covered
with a capillary network, the
most intricate in the body
(Fig. 36).
4. These tubes are some-
what flexible, sufficiently so to
bend when the parts move in
which they are situated ; but
they are greatly strengthened
by bands or rings of cartilage
which keep the passages always
open; otherwise there would
be a constantly-recurring ten-
dency to collapse after every
breath. The lung-substance
essentially consists of these
bronchial tubes and terminal
air-cells, with the blood-ves-
sels ramifying about them
(Fig. 37). At the top of the
trachea is the larynx, a sort of
FIG. 35. LARYNX, TRACHEA, AND
BRONCHIAL TUBES.
FTS. 36. DIAGRAM AND SECTION OF
THE AIR-CELLS.
4. Office of the bronchial tubes ? What further can you state of them ?
126 RESPIRATION".
box of cartilage, across which are stretched the vocal cords.
Here the voice is produced chiefly by the passage of the
respired air over these cords, causing them to vibrate.
FIG. 37. SECTION OP THE LUNGS.
5. Over the opening of the larynx is found the epiglottis,
which fits like the lid of a box at the entrance to the
lungs, and closes during the act of swallowing, so that
food and drink shall pass backward to the oesophagus, or
gullet (Fig. 38). Occasionally it does not close in time,
and some substance intrudes within the larynx, when we at
once discover, by a choking sensation, that "something has
gone the wrong way," and, by coughing, we attempt to ex-
pel the unwelcome intruder. The epiglottis is one of the
many safeguards furnished by nature for our security and
5. The epiglottis ? When it does not clo^c in time, wh$t is the consequence?
RESPIRATION.
12?
comfort, and is planned and put in place long before these
organs are brought into actual use in breathing and ?<i
taking food.
FIG. 38. SECTION OF MOUTH AND THROAT.
A, The Tongue.
B, The Uvula.
C, Vocal Cord.
E, Epiglottis.
L, Larynx.
N, Trachea.
O, (Esophagus.
6. The air -passages are liiiea tnrough nearly their
whole extent with mucous membrane, which maintains
these parts in a constantly moist condition. This mem-
brane has a peculiar kind of cells upon its outer sur-
6. Lining of the air-passages ? Ciliated cells ? Their uses ? The three dis-
eases of the lungs ?
128 RESPIRATION.
face. If examined under a powerful microscope, we may
see, even for a considerable time after their removal from
the body, that these cells have minute hair-like processes
in motion, which wave like a field of grain under the
influence of a breeze (Fig. 39). This is a truly beauti-
ful sight; and since it is found that these little cilia, as
they are called, always produce currents in one direction,
from within outward, it is probable that they serve a
useful purpose in catching and
carrying away from the lungs
dust and other small particles
drawn in with the breath (Fig.
39). The three diseases which
more commonly affect the lungs,
as the result of exposure, are
FIG 39 -CILIATED CELLS pneumonia, or inflammation of
the lungs, implicating principally
the air-cells; bronchitis, an inflammation of the large bron-
chial tubes; and pleurisy, an inflammation of the investing
membrane of the lungs, or pleura. Among the young, an
affection of the trachea takes place, known as croup.
7. The Movements of Respiration. The act of
breathing has two parts (1), inspiration, or drawing
air into the lungs, and (2), expiration, or expelling it
from the lungs again. In inspiration, the chest extends
in its length, breadth, and height, or width. We can
prove that this is the case as regards the two latter, by
observing the effect of a deep breath. The ribs are ele-
vated by means of numerous muscles, some of which oc-
cupy the entire spaces between those bones. But the
increase in length, or vertically, is not so apparent, as it is
caused by a muscle within the body called the diaphragm,
it being the thin partition which separates the chest from
the abdomen, rising like a dome within the chest. (Fig. 16).
7 The act of breathing ? Extension of the chest by breathing ?
RESPIRATION.
8. With every inspiration, the diaphragm contracts, and
in so doing, approaches more nearly a plane, or horizontal,
surface, and thus enlarges the capacity of the chest.
Laughing, sobbing, hiccoughing, and sneezing are caused
by the spasmodic or sudden contraction of the diaphragm.
The special power of this muscle is important in securing
endurance, or " long wind," as it is commonly expressed;
which may be obtained mainly by practice. It is possessed
in a marked degree by the mountaineer, the oarsman, and
the trained singer. As the walls of the chest extend, the
lungs expand, and the air rushes in to fill them. This
constitutes an inspiration. The habit of taking frequent
and deep inspirations, in the erect position, with the
shoulders thrown back, tends greatly to increase the ca-
pacity and power of the organs of respiration.
9. Expiration is a less powerful act than inspiration.
The diaphragm relaxes its contraction, and ascends in the
form of a dome; the ribs descend and contract the chest;
while the lungs themselves, being elastic, assist to drive
out the air. The latter passes out through the same chan-
nels by which it entered. At the end of each expiration
there is a pause, or period of repose, lasting about as long
as the period of action.
10. Frequency of Respiration. It is usually esti-
mated that we breathe once during every four beats of the
heart, or about eighteen times in a minute. There is, of
course, a close relation between the heart and lungs, and
whatever modifies the pulse, in like manner affects the
breathing. When the action of the heart is hurried, a
larger amount of blood is sent to the lungs, and, as the
consequence, they must act more rapidly. Occasionally,
the heart beats so very forcibly that the lungs cannot keep
pace with it, and then we experience a peculiar sense of
8. Contraction of the diaphragm ? Power of the diaphragm? Effects of ex-
pending the wails of the chest ? The habit of taking frequent and deep inspirations "(
9. Expiration ? The mechanism of expiration ?
1O. Frequency of respiration ? Effect of hurried action of the heart?
130 KESPI RATION.
distress from the want of air. This takes place when we
run until we are " out of breath." At the end of every
fifth or sixth breath, the inspiration is generally longer
than usual, the effect being to change more completely the
air of the lungs.
11. Although, as a general rule, the work of respiration
goes on unconsciously and without exertion on our part,
it is nevertheless under the control of the will. We can
increase or diminish the frequency of its acts at pleasure,
and we can "hold the breath," or arrest it altogether
for a short time. From twenty to thirty seconds is
ordinarily the longest period in which the breath can be
held ; but if we first expel all the impure air from the
lungs, by taking several very deep inspirations, the time
may be extended to one and a half or even two minutes.
This should be remembered, and acted upon, before pass-
ing through a burning building, or any place where the
air is very foul. The arrest of the respiration may be still
further prolonged by training and habit ; thus it is said,
the pearl-fishers of India can remain three or four minutes
under water without being compelled to breathe.
12. Capacity of the Lungs. The lungs are not
filled and emptied by each respiration. For while their
full capacity, in the adult, is three hundred and twenty
cubic inches, or more than a gallon, the ordinary breath-
ing air is only one-sixteenth part of that volume, or twenty
cubic inches, being two-thirds of a pint. Accordingly, a
complete renovation, or rotation, of the air of the lungs
does not take place more frequently than about once in a
minute ; and by the gradual introduction of the external
air, its temperature is considerably elevated before it
reaches the delicate pulmonary capillaries. In tranquil
respiration, less than two-thirds of the breathing power is
1 1 . Respiration controlled by the will ? Advantage of the knowledge to us ?
12. Capacity of the lungs? Time required to renovate the air in the lungs?
In tranquil respiration ? Importance of the provision ?
RESPIRATION. 131
called into exercise, leaving a reserve capacity of about one
hundred and twenty cubic inches, equivalent to three and
one half pints. This provision is indispensable to the con-
tinuation of life ; otherwise, a slight embarrassment of res-
piration, by an ordinary cold, for instance, would suffice
to cut off the necessary air, and the spark of life would
be speedily extinguished. (Read Note i.)
13. The Air we breathe. The earth is enveloped
on all sides by an invisible fluid, called the atmosphere.
It forms a vast and shoreless ocean of air, -forty-five miles
deep, encircling and pervading all objects on the earth's
surface, which is absolutely essential for the preservation of
all vegetable and animal life, in the sea, as well as on the
land and in the air. At the bottom, or in the lower strata
of this aerial ocean, we move and have our being. Per-
fectly pure water will not support marine life, for a fish
may be drowned in water from which the air has been ex-
hausted, just as certainly as a mouse, or any other land
animal, will perish if put deeply into the water for a length
of time. The cause is the same in both cases : the animal
is deprived of the requisite amount of air. It is also stated,
that if the water-supply of the plant be deprived of air, its
vital processes are at once checked.
14. The air is not a simple element, as the ancients sup-
posed, but is formed by the mingling of two gases, known
to the chemist as oxygen and nitrogen, in the proportion
of one part of the former to four parts of the latter. These
gases are very unlike, being almost opposite in their prop-
erties : nitrogen is weak, inert, and cannot support life ;
while oxygen is powerful, and incessantly active ; and is the
essential element which gives to the atmosphere its power
to support life and combustion. The discovery of this fact
was made by the French chemist, Lavoisier, in 1778.
13. The atmosphere ? How high or deep ? How essential to life ? Marine life
in perfectly pure water and air ?
J 4, Composition of the air ? Properties of the two gases ?
132 RESPIRATION.
15. Changes in the Air from Respiration. Air
that has been once breathed is no longer fit for respiration.
An animal confined within it will sooner or later die; so
too, a lighted candle placed in it will be at once extin-
guished. If we collect a quantity of expired air and ana-
lyze it, we shall find that its composition is not the same
as that of the inspired air. When the air entered the
lungs it was rich in oxygen ; now it contains twenty-five
per cent, less of that gas. Its volume, however, remains
nearly the same ; its loss being replaced by another and
very different gas, which the lungs exhaled, called carbonic
acid, or, as the chemist terms it, carbon dioxide.
16. The expired air has also gained moisture. This is
noticed when we breathe upon a mirror, or the window-
pane, the surface being tarnished by the condensation of
the watery vapor exhaled by the lungs. In cold weather,
this causes the fine cloud which is seen issuing from the
nostrils or mouth with each expiration, and contributes in
forming tHe feathery crystals of ice which decorate our
window-panes on a winter's morning.
17- This watery vapor contains a variable quantity of
animal matter, the exact nature of which is unknown; but
when collected it speedily putrefies and becomes highly
offensive. From the effects, upon small animals, of con-
finement in their own exhalations, having at the same
time an abundant supply of fresh air, it is believed that
the organic matters thrown off by the lungs and skin
are direct and active poisons; and that to such emana-
tions from the body, more than to any other cause, are
due the depressing and even fatal results which follow the
crowding of large numbers of persons into places of lim-
ited capacity. (Read Note 2.)
15. Air once breathed? An animal in it ? A candle? Analysis of expired air ?
Change in volume ?
1 6". What else has the expired air pained ? When and where noticed ?
1 7. Nature of the watery vapor ? Its effects upon animals ?
RESPIRATION. 133
18. History furnishes many painful instances of the ill
effects of overcrowding. In 1756, of one hundred and
forty-six Englishmen imprisoned in the Black Hole of
Calcutta, only twenty-three, at the end of eight hours
survived. After the battle of Austerlitz, three hundred
prisoners were crowded into a cavern, where, in a few
hours, two-thirds of their number died. On board a
steam-ship, during a stormy night, one hundred and
fifty passengers were confined in a small cabin, but
when morning came, only eighty remained alive.
\19. Changes in the Blood from Respiration.
The most striking change which the blood undergoes by
its passage through the lungs, is the change of color from
a dark blue to bright red. That this change is dependent
upon respiration has been fully proved by experiment.
If the trachea, or windpipe, of a living animal be so com-
pressed as to exclude the air from the lungs, the blood in
the arteries will gradually grow darker, until its color is
the same as that of the venous blood. When the pressure
is removed the blood speedily resumes its bright hue.
Again, if the animal be made to breathe an atmosphere
containing more oxygen than atmospheric air, the color
changes from scarlet to vermilion, and becomes even
brighter than arterial blood. This change of color is not
of itself a very important matter, but it indicates a most
important change of composition.
20. The air, as we have seen, by respiration loses oxy-
gen and gains carbonic acid : the blood, on the contrary,
gains oxygen and loses carbonic acid. The oxygen is the
food of the blood corpuscles; while the articles we eat and
drink belong more particularly to the plasma of the blood.
The air, then, it is plain, is a sort of food, and we should
18. Give some of the instances furnished by history.
1 J). Change in the blood from blue to red. Upon what does the change depend ?
How shown ?
2O. What does the air lose and gain by respiration ? What, the blood ? Air as
food?
134 RESPIRATION.
undoubtedly so regard it, if it were not for the fact that
we require it constantly, instead of taking it at stated in-
tervals, as is the case with our articles of diet. Again, as
the demand of the system for food is expressed by the sen-
sation of hunger, so the demand for air is marked by a
painful sensation called suffocation.
21. Interchange of Gases in the Lungs. As the
air and the blood are not in contact, they being separated
from each other by the walls of the air-cells and of the
blood-vessels, how can the two gases, oxygen and carbonic
acid, exchange places ? Moist animal membranes have a
property which enables them to transmit gases through
their substance, although they are impervious to liquids.
This may be beautifully shown by suspending a bladder
containing dark blood in a jar of oxygen. At the end of
a few hours the oxygen will h&ve disappeared, the blood
will be brighter in color, and carbonic acid will be found
in the jar.
22. If this interchange takes place outside of the body,
how much more perfectly must it take place within, where
it is favored by many additional circumstances! The
walls of the vessels and the air-cells offer no obstacle to
this process, which is known as gaseous diffusion. Both
parts of the process are alike of vital importance. If oxy-
gen be not received, the organs cease to act ; and if car-
bonic acid be retained in the blood, its action is that of a
poison; unconsciousness, convulsions, and death follow-
v ing.
/ 23. Difference between Arterial and Venous
Blood. The following table presents the essential points
of difference in the appearance and composition of the
blood, before and after its passage through the lungs :
21 . Moist animal membranes ? How shown with the bladder ?
22. Gaseous diffusion? If oxygen be not received? If carbonic acid be re-
tained ?
23. Difference in the appearance and composition of the blood? Temperature
of the blood ? The blood while passing through the lunar* ? The consequence ?
RESPIRATION". 135
Venous Blood.
Arterial Blood.
Color,
Dark blue,
Scarlet.
Oxygen,
8 per cent,
18 per cent.
Carbonic Acid,
15 to 20 per cent.,
6 per cent., or less.
Water,
More,
Less.
The temperature of the blood varies considerably; but
the arterial stream is generally warmer than the venous.
The blood imparts heat to the air while passing through
the lungs, and consequently the contents of the right side
of the heart has a higher temperature than the contents
on the left side.
24. By means of the spectroscope, we learn that the
change of color in the blood has its seat in the corpuscles ;
and that, according as they retain oxygen, or release it, they
present the spectrum of arterial or venous blood. There
evidently exists, on the part of these little bodies, an affin-
ity for this gas, and hence they have been called " carriers
of oxygen." It was long ago thought that blue blood was
a trait peculiar to persons of princely and royal descent,
and boastful allusions to the " sang azure" of kings and
nobles are quite often met with. Physiology, however, in-
forms us that blue blood flows in the veins of the low as
well as the high, and that so far from its presence indicat-
ing a mark of purity, it, in reality, represents the waste and
decay of the system.
25. Amount of Respiratory Labor. During or-
dinary calm respiration, we breathe eighteen times in a
minute ; and twenty cubic inches of air pass in and out of
the lungs with every breath. This is equivalent to the use
of three hundred and sixty cubic inches, or more than ten
pints of air each minute. From this we calculate that the
quantity of air which hourly traverses the lungs is about
thirteen cubic feet, or seventy-eight gallons; and daily, not
14. What do we learn by means of the spectroscope? " Carriers of oxygen?"
Blue blood in the system ?
25. The amount of air that passes in and out of the lungs ^
136 RESPIRATION.
less than three hundred cubic feet, an amount nearly equal
to the contents of sixty barrels.
26. Of this large volume of air five per cent, is absorbed
in its transit through the lungs. The loss thus sustained is
almost wholly of oxygen, and amounts to fifteen cubic feet
daily. The quantity of carbonic acid exhaled by the lungs
during the day is somewhat less, being twelve cubic feet.
Under the influence of excitement or exertion, the breath-
ing becomes more frequent and more profound; and then
the internal respiratory work increases proportionately,
and may even be double that of the above estimate. It
has been estimated that in drawing a full breath, a man
exerts a muscular force equal to raising two hundred
pounds placed upon the chest.
* 27. Impurities of the Air. The oxygen in the at-
/ mosphere is of such prime importance, and its proportion
is so nicely adjusted to the wants of man, that any gas or
volatile substance which supplants it must be regarded as
a hurtful impurity. All gases, however, are not alike in-
jurious. Some, if inhaled, are necessarily fatal; arsen-
uretted hydrogen being one of these, a single bubble of
which destroyed the life of its discoverer, Gehlen. Others
are not directly dangerous, but by taking the place of
oxygen, and excluding it from the lungs, they become so.
Into this latter class we place carbonic acid.
f^ 28. Most of the actively poisonous gases have a pungent
or offensive odor; and, as may be inferred, most repugnant
odors indicate the presence of substances unfit for respira-
tion. Accordingly, as we cannot see or taste these impu-
rities, the sense of smell is our principal safeguard against
them ; and we recognize the design which has planted this
sense, like a sentinel at the proper entrance of the air-
26. Air absorbed in its transit through the lungs? The loss ? Carbonic acid
exhaled ? Effect of excitement or exertion ? What estimate ?
27. Importance of the oxygen in the atmosphere? Injurious character ol
gases ?
28. Pungency of gases ? The inference ? Our safeguard ?
RESPIRATION-. 137
passages, the nostrils, to give us warning of approaching
harm. Take, as an example, the ordinary illuminating
gas of cities, from which so many accidents happen. How
many more deaths would it cause if, when a leak occurs,
we were not able to discover the escape of the gas by means
of its disagreeable odor.
29. Organic matters exist in increased measure in the
expired breath of sick persons, and impart to it, at times, a
putrid odor. This is especially true in diseases which,
like typhus and scarlet fever, are referable to a blood
poison. In such cases the breath is one of the means by
which nature seeks to expel the offending material from
the system. Hence, those who visit or administer to fever-
sick persons should obey the oft-repeated direction, " not
to take the breath of the sick." At such times, if ever,
fresh air is demanded, not alone for the sick, but as well
for those who are in attendance. (Read Notes 9 and 10.)
30. Dust in the Air. Attention has lately been di-
rected to the dust, or haze, that marks the ray of sunshine
across a shaded room. Just as, many years ago, it was dis-
covered that myriads of animalcula infested much of the
water we drank, so now the microscope reveals "the gay
motes that dance along a sunbeam" to be, in part, com-
posed of multitudes of animal and vegetable forms of a
very low grade, the germs of fermentation and putrefac-
tion, and the probable sources of disease.
31. It is found that the best filter by which to separate
this floating dust from the air is cotton wool, although a
handkerchief will imperfectly answer the same purpose.
In a lecture on this subject by Prof. Tyndall, he remarks
that, " by breathing through a cotton wool respirator, the
noxious air of the sick room is restored to practical purity.
Thus filtered, attendants may breathe the air unharmed.
29. The air of rooms in which fever-Pick persons are confined ?
30. Animalcula in the water V Dust in the air*
3 1 . The best air filter ? The remarks of Prof. Tyndall ?
138 RESPIRATION".
In all probability, the protection of the lungs will be the
protection of the whole system. For it is exceedingly
probable that the germs which lodge in the air-passages
are those which sow epidemic disease in the body. If this
be so, then disease can certainly be warded off by filters of
cotton wool. By this means, so far as the germs are con-
cerned, the air of the highest Alps may be brought into
the chamber of the invalid."
32. Carbonic Acid in the Air. We have already
spoken of this gas as an exhalation from the lungs, and a
source of impurity; but it exists naturally in the atmos-
phere in the proportion of one half part per thousand. In
volcanic regions it is poured forth in enormous quantities
from fissures in the earth's surface. Being heavier than
air, it sometimes settles into caves and depressions in the
surface. It is stated that in the island of Java, there is a
place called the " Valley of Poison," where the ground is
covered with the bones of birds, tigers, and other wild ani-
mals, which were suffocated by carbonic acid while passing.
The Lake Avernus, the fabled entrance to the infernal re-
gions, was, as its name implies, bird-less, because the birds,
while flying over it, were poisoned by the gas and fell dead
into its waters. In mines, carbonic acid forms the dreaded
choice-damp, while carburetted hydrogen is the fire-damp.
\ 33. In the open air, men seldom suffer from carbonic
acid, for, as we shall see presently, nature provides for its
rapid distribution, and even turns it to profitable use.
But its ill effects are painfully evident in the abodes of
men, in which it is liable to collect as the waste product of
respiration and of that combustion which is necessary for
lighting and warming our homes. A man exhales, during
repose, not less than one-half cubic foot of carbonic acid
per hour. One gas-burner liberates five cubic feet in the
32. Carbonic acid in volcanic regions ? In Java? At Lake Avernus ? In mines?
33. In the open air? Amount of carbonic acid exhaled by a man? A gas-
burner ? A room fire ? From furnaces ?
RESPIRATION. 139
same time, and spoils about as much air as ten men. A
fire burning in a grate or stove emits some gaseous impur-
ity, and at the same time abstracts from the air as much
oxygen as twelve men would consume in the same period,
thus increasing the relative amount of carbonic acid in
the air. From furnaces, as ordinarily constructed, this gas,
with other products of combustion, is constantly leaking
and vitiating the air of tightly-closed apartments.
34. Effects of Impure Air. Carbonic acid, in its
pure form, is irrespirable, causing rapid death by suffoca-
tion. Air containing forty parts per thousand of this gas
(the composition of the expired breath) extinguishes a
lighted candle, and is fatal to birds ; when containing one
hundred parts, it no longer yields oxygen to man and
other warm-blooded animals; and is of course at once
fatal to them. In smaller quantities, this gas causes head-
ache, labored respiration, palpitation, unconsciousness, and
convulsions.
35. In crowded and badly ventilated apartments, where
the atmosphere relatively contains from six to ten times
the natural amount of carbonic acid, the contaminated air
causes dulness, drowsiness, and faintness; the dark, im-
pure blood circulating through the brain, oppressing that
organ and causing it to act like a blunted tool. This is a
condition not uncommon in our schools, churches, court-
rooms, and the like, the places of all others where it is
desirable that the mind should be alert and free to act;
but, unhappily, an unseen physiological cause is at work,
dispensing weariness and stupor over juries, audience, and
(Read Notes 3 and 7.)
36. Another unmistakable result of living in and breath-
ing foul air is found in certain diseases of the lungs,
especially consumption. For many years the barracks of
pupils
34. Effects of inhaling carbonic acid alone ? In small quantities?
35. Effects of the air in crowded and badly ventilated rooms?
36. A cause of consumption ? How was the fact illustrated ?
140 KESPIRATIOK.
the British army were constructed without any regard tc>
ventilation; and during those years the statistics showed
that consumption was the cause of a very large proportion
of deaths, j^t last the government began to improve the
condition of the buildings, giving larger space and air-
supply; and as a consequence, the mortality from con-
sumption has diminished more than one-third.
37. The lower animals confined in the impure atmos-
phere of menageries, contract the same diseases as man.
Those brought from a tropical climate, and requiring arti-
ficial warmth, generally die of consumption. In the Zoo-
logical gardens of Paris, this disease affected nearly all
monkeys, until care was taken to introduce fresh air by
ventilation; and then it almost wholly disappeared. The
tendency of certain occupations to shorten life is well
known; disease being occasioned by the fumes and dust
which arise from the material employed, in addition to the
unhealthful condition of the workshop or factory where
many hours are passed daily. (Read Note 4.)
38. The following table shows the comparative amount
of carbonic acid in the air under different conditions and
the effects sometimes produced:
PROPOKTION OF CARBONIC ACID. in 1000 parts of Air.
A.ir of country 4
" " city 5
In hospital, well ventilated 6
In school, church, etc., fairly ventilated 1.2 to 2.5
In court-house, factory, etc., without ventilation.. .. 4. to 40.
In bedroom, before being aired 4.5
In bedroom, after being aired 1.5
Constantly breathed, causing ill health 2.
Occasionally breathed, causing discomfort 3.
Occasionally breathed, causing distress 10.
Expired air 40.
Air no longer yielding oxygen 100.
3 7. How, in the case of the lower animals ? Tendency of certain occupations ?
38. Give the fact as set forth in the table.
RESPIKAT10N. 141
39. Nature's Provision for Purifying the Air.
We have seen that carbonic acid is heavier than air, and
is poisonous. Why, then, does it not sink upon and over-
whelm mankind with a silent, invisible wave of death ?
Among the gases there is a more potent force than gravity,
which forever precludes such a tragedy. It is known as
the diffusive power of gases. It acts according to a defi-
nite law, and with a resistless energy compelling these
gases, when in contact, to mingle until they are thor-
oughly diffused. The added influence of the winds is
useful, by insuring more rapid changes in the air; air in
motion being perfectly wholesome. The rains also wash
the air.
40. We have seen that the whole animal creation is con-
stantly abstracting oxygen from the atmosphere, and as
constantly adding to it vast volumes of a gas injurious alike
to all, even in small quantities. How, then, does the air re-
tain, unchanged, its life-giving properties ? The constant
purity of the air is secured by means of the vegetable cre-
ation. Carbonic acid is the food of the plants, and oxygen
is its waste product. The leaves are its lungs, and under
the stimulus of sunlight a vegetable respiration is set in
motion, the effects of which are just the reverse of the
function we have been considering. Thus nature purifies
the air, and at the same time builds up beautiful and use-
ful forms of life from elements of decay. (Read Note 5.)
41. In the sea, as in the air, the same circle of changes
is observed. Marine animals consume oxygen and give off
carbonic acid; while marine plants consume carbonic acid
and liberate oxygen. Taking advantage of this fact, we
may so arrange aquaria with fishes and sea-plants, in their
proper combinations, so that each supplies the needs of the
other, and the water requires seldom to be renewed. This
39. What can you state of the diffusive power of gases ? The added influence
of the winds?
40. How is the constant purity of the air secured ? Explain the process ?
4 1 . What process occurs in the sea '( How is the fact illustrated 1
142 RESPIRATION.
affords us, on a small scale, an illustration of the mutual
dependence of the two great kingdoms of nature; as well
as of those compensating changes which are taking place
on such a grand scale in the world about us.
/ 42. Ventilation. Since the external atmosphere, as
provided by nature, is always pure, and since the air in our
dwellings and other buildings is almost always impure, it
becomes imperative that there should be a free communica-
tion from the one to the other. This we aim to accomplish
by ventilation. As our houses are ordinarily constructed,
the theory of ventilation, "to make the internal as pure as
the external air," is seldom carried out. Doors, windows,
and flues, the natural means of replenishing the air, are
too often closed, almost hermetically, against the precious
element. Special means, or special attention, must there-
fore be used to secure even a fair supply of fresh air. This
is still more true of those places of public resort, where
many persons are crowded together.
'\ 43. If there are two openings in a room, one as a vent
for foul air, and the other an inlet for atmospheric air,
and if the openings be large, in proportion to the number
of air consumers, the principal object will be attained.
Thus, a door and window, each opening into the outer air,
will ordinarily ventilate a small apartment ; or a window
alone will answer, if it be open both above and below, and
the open space at each end be not less than one inch for
each occupant of the room, when the window is about a
yard wide. The direction of the current is generally from
below upward, since the foul, heated air tends to rise;
but this is not essential. Its rate need not be rapid ; a
"draught," or perceptible current, is never necessary to
good ventilation. The temperature of the air admitted
may be warm or cold. It is thought by many that if the
42. Character of the external air? Of the air in onr dwellings ? What becomes
imperative ? Imperfect ventilation of our dwellings?
43. What hints are given for the ventilation of our dwellings ?
RESPIRATION. 143
air is cold, it is pure ; but this is an error, since cold air
will receive and retain the same impurities as warm air.
44. Shall we open our bedrooms to the night air ? Flor-
ence Nightingale says, in effect, that night air is the only
air that we can then breathe. " The choice is between pure
air without and impure air within. Most people prefer the
latter, an unaccountable choice. An open window, most
nights in the year, can hurt no one. In great cities, night
air is the best and purest to be had in twenty-four hours.
I could better understand, in towns, shutting the windows
during the day than during the night." (Read Notes 6 and 7.)
45. Animal Heat. Intimately connected with respi-
ration is the production of animal heat, or the power of
maintaining the temperature of the body above that of the
medium in which the creature moves; thus, the bird is
warmer than the air, and the fish than the water. This
elevation of temperature is a result of the various chemi-
cal changes which are constantly taking place in the system.
Although common to all animals, in a greater or less
degree, heat is not peculiar to them ; since plants also gen-
erate it, especially at the time of sprouting and flowering.
If a thermometer be placed in a cluster of geranium flow-
ers, it will indicate a temperature several degrees above
that of the surrounding air.
46. Among animals great differences are noticed in this
respect, but the degree of heat produced is always propor-
tional to the activity of respiration and the amount of
oxygen consumed. Accordingly, the birds, whose habits
are extremely active, and whose breathing capacity is the
greatest, have uniformly the highest temperature. Slug-
gish animals, on the contrary, as frogs, lizards, and snakes,
have little need for oxygen, and have incompletely de-
44. State what Florence Nightingale says about inhaling night air?
45. Warmth of the bird as compared with that of the air? Of the fish and
the water ? Heat in animals and plants ? How illustrated with the thermometer ?
46. Amount of heat in animals, how apportioned ? As regards the birds?
Frogs, and other sluggish animals ? Arrangement made by zoohgsts ?
144 RESPIRATION.
veloped lungs ; these animals are cold to the touch, that is,
they have relatively a lower temperature than man, and
their positive temperature is but little above that of the
external air. Accordingly, zoologists have so arranged the
animal kingdom that warm-blooded animals, including
man, the birds, and the quadrupeds, are classified together;
while the cold-blooded animals, such as the fish, tortoise,
frog, and all tnat have no vertebral column, are classed
by themselves.
47. The temperature of the human body is about 100
Fahrenheit, and remains about the same through winter
and summer, in the tropics as well as in the frozen regions
of the north. It may change temporarily within the range
of about twelve degrees; but any considerable, or long-con-
tinued elevation or diminution of the bodily heat is certain
to result disastrously.
48. Man is able to adapt himself to all extremes of
climate; and, in fact, by means of clothing, shelter, and
food, is able to create for himself an artificial climate where-
ever he choses to reside. The power to resist cold consists
chiefly in preventing the heat which is generated by the
vital processes of the body from being lost by radiation.
Warm clothing, such as we wear in winter, has, in reality,
the same temperature as that which is worn in summer;
but, by reason of being thick and porous, it is a bad con-
ductor of heat, and thus prevents the escape of that
produced by the body. If woollen fabrics were intrinsically
warm, no one would wrap a piece of flannel, or blanket,
around a block of ice to prevent its melting in summer.
49. The faculty of generating heat explains how it is
that we are enabled to resist the effects of cold; but how
does the body withstand a temperature higher than its
47. State what is said respecting the temperature of the human body.
48 - Ability of man to adapt himself to different climate;* ? In what does the
power to resist cold consist ? What is said about warm clothing?
49. Men in an atmosphere above the boiling-point ? In foundries and glass.
works ?
RESPIRATION. 145
own ? Men have been known to remain several minutes in
an atmosphere heated above the boiling-point of water, and
yet the temperature of their own bodies was not greatly ele-
vated. Those who labor in foundries and glass-works are
habitually subjected to very high degrees of temperature,
but they do not suffer in health more than those engaged
in many other occupations.
50. The regulation of the temperature of the body is
effected by means of perspiration, and by its evaporation.
So long as the skin acts freely and the air freely absorbs
the moisture, the heat of the body does not increase, for
whenever evaporation takes place, it is attended by the
abstraction of heat that is, the part becomes relatively
colder. This may be tested by moistening some part of
the surface with cologne, ether, or other volatile liquid,
and then causing it to evaporate rapidly by fanning. The
principle that evaporation produces cold has been in-
geniously and practically employed, in the manufacture
of ice, by means of freezing machines. (Read Note 8.)
51. Spontaneous Combustion. Is it possible that
the temperature of the living body can be so increased,
that its tissues will burn spontaneously ? From time to
time, cases have been reported in which, by some mysteri-
ous means, considerable portions of the human body have
been consumed, apparently by fire, the victim being found
dead, or inqapable of explaining the occurrence. Hence,
the theory has been current that, under certain condi-
tions, the tissues of the body might become self-ignited ;
and the fact that this so-called spontaneous combustion
has ordinarily taken place in those who had been addicted
to the use of alcoholic drinks, has given a color of proba-
bility to the opinion. It has been supposed that the flesh
of these unfortunate persons becoming saturated with the
inflammable properties of the alcohol thus taken into the
50. The regulation of the temperature of the body. Give the explanation.
51, 52. State what is said of spontaneous combustion.
146 RESPIRATION.
system, took fire upon being exposed to a flame, as of &
lighted candle, or, indeed, without any external cause. But,
whether this be possible or not, one thing is certain, this
strange kind of combustion has never been actually wit-
nessed by any one competent to give a satisfactory account
of it.
52. The results that have been observed may be satis-
factorily explained by the accidental ignition of the clothes,
or other articles near the body, and by the supposition
that the individual was at the time too much stupefied by
intoxication, to notice the source of danger, and provide
for his safety. The highest temperature that has been
observed in the body, about 112 Fahrenheit, is too low
to ignite the vapor of alcohol; much less will it cause
the burning of animal tissues. It is undoubtedly true
that when the tissues are filled with alcohol, combus-
tion will more easily take place than when the body is in
a normal state ; but, under any condition, the combustion
of the body requires a higher degree of heat than can be
generated by the body itself, or the mere proximity of a
lighted candle, or any cause of a similar character.
HEVIEW QUESTIONS. 147
QUESTIONS FOR TOPICAL REVIEW.
PAGE
1. What is the object of respiration? 123
2. What are the special organs of respiration ? 123
3. In what organs do :s a change in the blood take place ? 123
4. What is the nature of the change ? 123, 133
5. Where are the lungs situated, and what is the character of the sub-
stance of which they are composed ? 123, 125
6. Describe the facilities provided for the lung movements 124
7. Describe the trachea, or windpipe 124, 125, 127, 128
8. Describe the bronchial tubes, and their uses 125, 126
9. What can you state in relation to the epiglottis 9 126, 127
10. What are the cilia and what use do they probably serve? 128
11. How may the lungs be affected by not being properly protected ? 128
12. Describe the movements necessary to the act of perfect respiration. . . 128, 123
13. What is the diaphragm, and what is its office? 128, 129
14. How may the organs of respiration be so improved as to increase their
capacity and power ? 129, 37
15. What is stated in relation to the frequency of respiration ? 129, 130
16. To what extent may the act of respiration be subjected to our wills ? 130
17. What may be said to be the capacity of the lungs ? 130, 131
18. How long does it take every particle of air in the lungs to be expelled and
new air to take its place ? 130
19. What would be the consequences, if the entire capacity of the lungs
were constantly used ? 130, 131
20. What would be the consequences to a fish put into water from which the
air had been completely exhausted ? Why ? 13J
21. What is the air, and what are its parts ? 131, 136, 138
22. What is the character of the air that has been just breathed ? 132
23. Why is it that such air is not fit for respiration ? 132, 139
24. What are the effects, as recorded in notable cases, of confinement in places
the air of which has been breathed kt over and over ?" 133
25. What can you state of changes in the blood from respiration ? 133
26. What of the air, as an article of food ? 133, 134
27. What, on the subject of interchange of gases in the lungs ? 134
28. Explain the difference between arterial and venous blood 134, 135
29. Explain, if you can, the cause of the difference 135
30. State what you can in relation to blue blood 135
31. In relation to the amount of labor exerted in respiration 135, 156
32. In relation to the deleterious properties of different gases 136, 137
33. In relation to the dust that floats in the air 137, 138
34. What are the properties of carbonic acid gas ? 132, 138, 141
35. In what places is carbonic acid gas commonly found ? 132, 138, 139
36. Describe the effects of carbonic acid gas 132, 128, 139, 141
37. What are the general effects of breathing any impure atmosphere ? 139, 140
38. What are Nature's provisions for purifying the air ? 141, 142
39. What hints and directions are given on the subject of ventilation ?. . . . 142, 143
40. How does the temperature of the body compare with the medium in which
it lives ? 143
41. How is temperature of the body regulated and sustained ? 148, 144, 145
4-7. State what you can on the subject of spontaneous combu.-Uoa 145. 146
NOTES.
1. The Atmosphere (p. 131, 1 13). "It surrounds us on all sides, yet wo
see it iiot ; it presses on us with a load of fifteen pounds to every square inch of
surface of our bodies, or from seventy to one hundred tons on us in all, yet we do
not so much as feel its weight. Softer than the softest down more impalpable
than the finest gossamer it leaves the cobweb undisturbed, and scarcely stirs the
lightest flower that feeds on the dew it supplies ; yet it bear? the fleets of nations
on its wings around the world, and crushes the most refractory substances
beneath its weight. When in motion, its force is sufficient to level the most
stately forests with the earth ; to raise the waters of the ocean into ridges like
mountains, and dash the strongest ships to pieces like toys. It bends the rays of
the sun from their path, to give us the twilight of evening and of dawn ; it
disperses and refracts their various tints, to beautify the approach and retreat of
the orb of day. But for the atmosphere, sunshine would burst on us and fail us
at once, and at once remove us from midnight darkness to the blaze of noon.
We should have no twilight to soften and beautify the landscape, no clouds to
shade us from the scorching heat ; but the bald earth, as it revolved on its axis,
would turn its tanned and weakened front to the full and unmitigated rays of the
lord of day." Buith.
2. The Two Breaths (p. 132, 1 17)." Every time you breathe, you breathe
two different breaths : you take in one, you give out another. The composition
of those two breaths is different. Their effects are different. The breath which
has been breathed out must not be breathed in again. To te'l you why it must
not would load me into anatomical details, not quite in place here as yet ; but this
I may say : those who habitually take in fresh breath will probably grow up large
strong, ruddy, cheerful, active, clear-headed, fit for their work. Those who habitu-
ally take in the breath which has been breathed out by themselves, or any other
living creature, will certainly grow up, if they grow up at all, small, weak, pale,
nervous, depressed, unfit for work, and tempted continually to resort to stimu-
lants, and become drunkards.
"If you want to see how different the breath breathed out is from the breath
taken in, you have only to try a somewhat cruel experiment, but one which, peo-
ple too often try upon themselves, their children, and their work-people. If you
take any small animal with lungs like your own a mouse for instance and force
it to breathe no air but what you have breathed already ; if you put it in a closo
box, and, while you take in breath from the outer air, send out your breath
through a tube into that box, the animal will soon faint; if you go on long with
this process, he will die. * * * * What becomes of this breath which passes from
your lips ^ Is it merely harmful, merely waste ? God forbid I God has forbidden
that anything should be merely harmful or merely waste in this so wise and well-
made world. The carbonic acid which passes from your lips at every breath is a
precious boon to thousands of things of which you have daily need. For though
you must riot breath your breath atrain, you may at least eat your breath, if you
will allow the sun to transmute it for you into vegetables ; or you may enjoy its
fragrance and its color in the shape of a lily or a rose. When you walk in a sunlit
garden, every word you speafc, every breath you breathe, is feeding the plants and
flowers around." Rev. Charles Kinqsley on the Two Breaths.
3. The Ground- Atmosphere audits Relations to Dwellings
(p. 139, 1 35). "The soil, which naturally contains wholesome air, and gives
facility to its every movement, is not less permeable by poisonous gases, which
are often found to pervade and issue from it. It is easy to find illustrations of
the fact that people are poisoned through the ground, since it is almost a daily
NOTES.
occurrence. Here is one, related by an eminent authority, von Pettenkofer: ' In
a residence at Augsburg, apparently endued with every qualification for health
and comfort, several priests lived together. On a certain morning one of these,
not the least zealous and prompt in the performance of his duties, was missed
from his usual post at thematiu service. His colleagues hurried back to their
common dwelling in search of the missing priest, and found him lying prostrate
and insensible upon the floor of his bed-chamber. A doctor was immediately
culled in, and at the first sight of his patient, declared him to be suffering from an
attack of typhus fever. The Sisters of Charity, upon whom devolved the duty of
nursing him, and those clerical associates who were active in their sympathy and
prompt to visit him and give assistance, were, a few hours after, attacked in the
same way. The doctor did not hesitate in his diagnosis, and pronounced the
additional cases also typhus fever. A general alarm prevailed in the city, and
many called at the house of the priest, wiio was greatly beloved. Among others,
was an old woman, who discovered a strong smell of gas, and believing this to bo
the cause of the sickness, obtained permission to remove the priest to her own
house. The priest had no sooner breathed the fresh air than he began to revive,
and during the very first evening of his removal to the new abode he became so
much beiter as to make an importunate demand for food. He soon got entirely well.
The old woman, thus confirmed in her gas theory, and eager to save the remain-
ing patients, who had continued to increase in number in the priests' house, now
had an interview with the manasrer of the gas-works which supplied the town,
aud prevailed upon him to investigate the condition of the gas-pipes in the
vicinity of the priest's residence. This wns done, and a leak from which the gas
was escaping into the ground was found and stopped. The air of the house was
perceived at once to improve, and with it the health of the patients that were not
removed ; these finally completely recovered from what the doctor even was com-
pelled to admit was not typhus fever, but poisoning by gas. 111 The Book of
Health.
4. Consumption Is Lung Starvation (p. 140, T 37). "The practiceof
allowing the lungs only improper food, in the form of vitiated air, is one of the
most prevalent habits of civilized life, and diseases of the lungs are its greatest
bane and greatest dread. More persons die by consumption than by any other
single disease. If there be added to those the large number that, perish every
year by inflammation of the lungs and bronchial tubes, disease and premature
death may be well said to have in these organs their chief citadel. The leading
cause of all this is, undoubtedly, the poor quality of the food on which the lungs
are nurtured. The very best physicians, when their attention is directed to the
subject, admit the full force of this conclusion, and that it has not received the
attention it deserves. Professor Hartshorne remarks on this point, that 'the
influence of impure air in promoting consumption has probably heretofore been
underrated.' 'The vitiated air of the European barrack system for soldiers,'
s-iys Professor Parkes, ' is the only way in which the great prevalence of con-
sumption in European armies can be accounted for.' This is the conclusion to
which the Sanitary Commissioners for the army came, in their celebrated report :
' A great amount of phthi-is (consumption) has prevailed in the most varied
stations ot the army and in the most beautiful climates in Gibraltar, Malta,
Ionia. Jamaica, Trinidad, Bermuda, etc. in all of which places the only common
condition was the vitiated atmosphere which our barrack system everywhere pro-
duced. And, as if to clinch the argument, there has been of late years a most
decided decline in phthisis in these stations, while the only circumstance which
NOTES.
has notably changed in the time has been the condition of the air.' A very. emi-
nent authority, the late Dr. Marshall Hall, of England, said, in reference to pure
air in the treatment of consumption, ' If I were seriously ill of consumption, I
would live out doors day and night, except in rainy weather, or midwinter ; then
I would sleep in an unplastered log house. Physic has no nutriment, gaspings for
air cannot, cure you, monkey capers in a gymnasium cannot cure you, and stimu-
lants cannot cure you. What consumptives want is pure air, not physic pure
air, not medicated air plenty of meat and bread.' Let it be remembered, in this
connection, that every hygienic or health-promoting measure which tends to cure
a disease is much more efficacious in preventing it." Black's Ten Laws of Health.
5. Plants and the Air (p. 141, 1 40). "Though the air is dependent for
the renewal of its oxygen on the action of the green leaves of plants, it must not
be forgotten that it is only in the presence and under the stimulus of light that
these organisms decompo-e carbonic acid. All plants, irrespective of their kind
or nature, absorb oxygen and exhale carbonic acid in the dark. The quantity of
noxious gas thus eleminated is, however, exceedingly small when compared with
the oxygen thrown out during the day. Aside from the highly deleterious
action that plants may exert on the atmosphere of a sleeping room, by
increasinsr the proportion of carbonic acid during the night, there is another
and more important objection to be urged against their presence i"a such
apartments. Like animals, they exhale peculiar volatile organic principles,
which in many instances render the air unfit for the purposes of respiration.
Even in the days of Andronicus this fact was recognized, for he says, in
epeaking of Arabia Felix, that ' by reason of myrrh, frankincense, and hot spices
there growing, the air was so obnoxious to thjir brains, that the very inhabitants
at some times cannot avoid its influence. 1 What the influence on the brains of
the inhabitants may have been does not at present interest us : we have only
quoted the statement to show that long ago the emanations from plant? were
regarded as having an influence on the condition of the air ; and, in view of our
present ignorance, it would be wise to banish them from our sleeping apartments,
at least until we are better informed regarding their true properties." draper on
Poisoned Air.
6. Pure Air in our Homes during Cold Weather (p. 143, 1 44).
" Fresh air is the great natural disinfectant, antiseptic, and purifier, and not to
be compared for a moment with any of artificial contrivance. There is plenty
of it in the world ; yet, disguise the fact as we may, there is no getting over the
unwelcome truth, that to provide in abundance in our climate is expensive,
since during seven months in the year it must be artificially Maimed, in cider
that our homes may be comfortable. To take in air at the average winter tem-
perature of 28, raise it to 68, and discharge it again from our houses even once
in an hour, is a process which cannot be accomplished without paying roundly;
yet on no other condition can we reasonably expect health and long life. The
best way is to freely admit that it is expensive, but worth the money it costs.
If Benjamin Franklin thought that ' a penny saved is a penny earned,' he is
equally sure that 'health is wealth.' "George Derby on the Prevention of Disease.
7. Pure Air and Good Morals (p. 139, If 35) " Cleanliness and self-
respect go together, and it is no paradox to affirm that you tend to purify men's
thoughts and feelings when you purify the air they breathe. * * * * With a
low average of popular health you will have a low average of national morality,
and probably also of national intellect. Drunkenness and vice of other kinds will
flourish in such a soil, and you cannot get healthy brains to grow on unhealthy
bodies.' 1 - Lord Derby..
NOTES.
8. Animal Heat (p. 145, ^ 50). " Infants produce much less heat during
their early days than during any later period of their life ; their temperature falls
very easily, therefore, and the influence of cold is especially hurtful to them. For
this reason, and because those who have care of them do not know the facts,
young children die from exposure in much larger numbers during the winter than
any other season of the year. * * * * But how is it that warm-blooded animals
can preserve their own proper heat when they are placed in an air that is hotter
than their bodies ? A man, for example, can remain for a certain time in an oven
where the air is raised to a temperature nearly equal to that of boiling water,
without a marked increase of the heat of the body; it rises a few degrees only."
Exposures of this kind cannot be long continued, on account, as it is supposed, of
an expansion of the blood. A case is on record of a person remaining ten minutes
in a dry hot-air bath, at 284, or seventy-two degrees above the boiling point of
water; and Chabert, the so-called "Fire-King," went into ovens heated from 400
to 000 degrees, but, of course, for a much shorter period. Sun heat is often fatal,
even in the temperate zone, but still more frequently in the tropics, amongst
troops on the march and amongst coolies working on plantations or on public
works. In Pekin during about ten days in July, 1743, the thermometer stood at
the extreme height of 104 in the shade, and, in that period, 11,400 people died.
Habit accustoms the Chinese, negroes, and others to bear a greater heat than the
natives of temperate climates can support. " The faculty of resisting heat depends
upon the evaporation of water which takes place continually from the skin and
lungs, and which constitutes the 'cutaneous and pulmonary transpiration;' for
water, as it changes into vapor, carries off the caloric of whatever surrounds it,
and thus the body is cooled in proportion as the external heat warms it. It is on
thisprinciple that water placed in certain porous vessels called 'alcarazas,' becomes
cool so promptly, even in midsummer. These vases permit the water contained
in them to leak out through numerous pores, so that their surface is constantly
moist; by a rapid evaporation of this moisture, the liquid within is made cool."
Milne- Edwards on " Zoologie."
9. Cleanliness the Sum Total of Hygiene (p. 137, t 29). Disinfect-
ants have the power of destroying tlie cause and of arresting the spr< ad of most epi-
demics and contagious diseases, but cleanliness is the best preventive of disease.
Whenever practicable, the abundant use of water is better than disinfection.
"Let no one ever depend upon disinfectants, fumigations, and the like, for puri-
fying the air. The offensive thing, not its smell, must be removed. Florence
Nightingale, Notes on Nursing (in pent.)
10. The True Prevention of Epidemics (p. 137, 1 29).-" It was
in England that solution of the great problem of hygiene was first attempted :
'Preventive Medicine,' it is there called. Palmerston told a deputation which
waited on him in order to ask him to order a fast on the approach of the second
epidemic of cholera, to cleanse their sewers and diligently visit the dwellings of
the poor. And he did not confine himself to good advice, but, with his usual
energy, he laid his hand on sanitary legislation, and purified the air of London,
and the large manufacturing towns. The result of the sanitary measures carried
out was a reduction of ihe mortality of London from 26 to 23 per 1,000, and in
some of the towns to 17 per 1,000 a low death-rate previously only equalled in
the Isle of Wight. More than four thousand lives have been preserved yearly in
London ; and, assuming that the mortality among the sick is 1 in 20, this number
represents a diminution in yearly sickness to the extent of eighty thousand. '*-
Dr. Joseph Seegen in the Vienna Medical Weekly.
148 THE NERVOUS SYSTEM.
CHAPTER IX.
THE NERVOUS SYSTEM.
Animal and Vegetative Functions Sensation, Motion, and Volition
The Structure of the Nervous System The White and Gray Sub-
stances The Brain Its Convolutions The Cerebellum The Spi-
nal Cord and its System of Nerves The Anterior and Posterior
Roots Tlie Sympathetic System of Nerves The Properties of Nerv-
ous Tissue Excitability of Nervous Tissues TJie Functions of the
Spinal Nerves and Cord The Direction of the Fibres of the Cord
Reflex Activity, and its Uses The Functions of the Medulla Oblon-
gata and the Cranial Ganglia The Reflex Action of tlie Brain.
1. Animal Functions. The vital processes which we
have been considering, in the three previous chapters, of
digestion, circulation, and respiration belong to the class
of functions known as vegetative functions. That is, they
are common to vegetables as well as animals; for the
plant, like the animal, can originate nothing, not even
the smallest particle of matter; and yet it grows, blossoms,
and bears fruit, by reason of obtaining and digesting the
nutriment which the air and soil provide. The plant has
its circulatory fluid and channels, by which the nutriment
is distributed to all its parts. It has, also, a curious ap-
paratus in its foliage, by which it abstracts from the air
those gaseous elements so necessary to its support; and
thus it accomplishes vegetable respiration. These vege-
tative functions have their beginning and end within the
organism of the plant; and their object is the preservation
of the plant itself, as well as of the entire species.
2. The animal, in addition to these vegetative functions,
has another set of powers, by the use of which he becomes
conscious of a world external to himself, and brings him-
1. What processes are known as the vegetative functions? Why so called?
What properties and functions does the plant possess ? Their object ?
2. What second set of powers has the animal ? What functions are mentioned ?
The advantage they give ?
:
THE NERVOUS SYSTEM. 149
St- If into active relations with it. By means of the vege-
tative processes, his life and species are maintained; while,
by means of certain animal functions, he feels, acts, and
thinks. These functions, among which are sensation,
motion, and volition, not only distinguish the animal from
the plant, but, in proportion to their development, elevate
oiitf creature above another; and it is' by virtue of his pre-
eminent endowment, in these respects, that man holds his
position at the head of the animal creation.
3. Among animals whose structure is very simple, the
hydra, or fresh-water polyp, being an example, no special
organs are empowered to perform separate functions ; but
every part is endowed alike, so that if the animal be cut
into pieces, each portion has all the properties of the entire
original; and, if the circumstances be favorable, each of
the pieces will soon become a complete hydra. As we ap-
proach man, in the scale of beings, we find that the organs
multiply, and the functions become more complete. The
function of motion, the instruments of which the muscles
and bones have been considered in former chapters, and
all the other animal functions of man, depend upon the set
of organs known as the nervous system.
4. The Nervous System. The intimate structure
of this system differs from any tissue which we have be-
fore examined. It is composed of a soft, pulpy substance,
which, early in life, is almost fluid, but which gradually
hardens with the growth of the body. When examined
under the microscope, it is found to be composed of two
distinct elements : (1) the white substance, composing
the larger proportion of the nervous organs of the body,
which is formed of delicate cylindrical filaments, about
6o * 00 of an inch in diameter, termed the nerve-fibres ; and
(2) the gray substance, composed of grayish-red, or ashen-
3. Animals whose structure is simple? As we approach man? Dependence
of the animal functions of man ?
4. The nervous tissues, of what composed ? When examined by the aid of the
microscope ? The white substance ? The gray substance ?
-
150 THE NERVOUS SYSTEM,
colored cells, of various sizes, generally possessing one or
more off-shoots, which are continuous with the nerve-
fibres just mentioned.
5. The gray, cellular substance constitutes the larger
portion of those important masses, which bear the name of
nervous centres and ganglia (from ganglion, a knot), and
in which all the nerve-fibres unite. These white nerve-
fibres are found combined together in long and dense
cords, called nerves (from neuron, a cord), which serve to
connect the nervous centres with each other, and to place
them in communication with all the other parts of the
body which have sensibility or power of motion. That
part of the nervous system which is concerned in the ani-
mal functions, comprises the brain, the spinal cord, and the
nerves which are derived therefrom; these are, together,
called the cerebro- spinal system (Fig. 40) ; while that other
set of organs, which presides over, and regulates the vege-
tative functions, is called the sympathetic system of nerves.
6. The Brain. The brain is the great volume of nerv-
ous tissue that is lodged within the skull. It is the largest
and most complex of the nervous centres, its weight, in the
adult, being about fifty ounces, or one-fortieth of that of
the whole body. The shape of the brain is oval, or egg-
shaped, with one extremity larger than the other, which is
placed posteriorly in the skull, to the concavity of which it
very closely conforms. The brain consists chiefly of two
parts; the cerebrum, or brain proper, and the cerebellum,
or "little brain." In addition to these, there are several
smaller organs at the base, among which is the commence-
ment or expansion of the spinal cord, termed the medulla
oblongata, or oblong marrow.
7. The tissue of the brain is soft and easily altered in
5. Nervous centres and ganglia? Nerves? What do they serve? Cerebro-
epinal system ?
6. Location of the brain ? Its weight? Its shape ? Of what, it consists ? What
organs at the base ?
7. The tissue of the brain ? What, therefore, is required ? Blows on the head ?
Hcmbranes of the brain ? Blood sent to the brain ?
THE NERVOUS SYSTEM.
151
FIQ. 40. THE CEREBKO-SPINAL SYSTEM.
152 THE NEBYOUS SYSTEM.
shape by pressure; it therefore requires to be placed in a
well-protected position, such as is afforded by the skull, or
cranium, which is strong without being cumbrous. In
the course of an ordinary lifetime, this bony box sustains
many blows, with little inconvenience; while, if they fell
directly upon the brain, they would at once, and com-
pletely, disorganize that structure. < Within the skull, the
brain is enveloped by certain memlSranes, which at once
protect it from friction, and furnish it with a supply of
nutrient vessels; they are called the arachnoid, or "spider's
web," the dura mater and the pia mater, or the "tough"
and "delicate coverings." The supply of blood sent to
the brain is very liberal, amounting to one-fifth of all
that the entire body possesses. The' brain of man is
heavier than that of any other animal, except the ele-
phant and whale.
8. The Cerebrum. The brain proper, or cerebrum, is
J the largest of the intracranial organs, and occupies the en-
tire upper and front portion of the skull. It is almost com-
pletely bisected, by a fissure, or cleft, running through it
lengthwise, into two equal parts called hemispheres. The
exterior of these hemispheres is gray in color, consisting
chiefly of nerve-cells, arranged so as to form a layer of gray
matter one-fifth of an inch in thickness, and is abundantly
supplied with blood-vessels. The interior of the brain,
however, is composed almost wholly of white substance, or
nerve-fibres.
9. The surface of the cerebrum is divided by a consid-
erable number of tortuous and irregular furrows, about
an inch deep/ into "convolutions," as shown in Fig. 41.
Into these furrows the gray matter of the surface is ex-
tended, and, in this manner, its quantity is vastly in-
creased. The extent of the entire surface of the brain,
8. Size of the brain proper? How divided? The exterior of the hemispheres ?
The interior ?
9. The surface of the cerebrum, how marked ? The gray matter of the surface ?
Extent of the entire brain surface ? Source of nervous power ? What further ?
THE NERVOUS SYSTEM.
153
with the convolutions unfolded, is computed to be equal to
four square feet ; and yet it is easily enclosed within the
narrow limits of the
skull. When it is
stated that the gray
matter is the true
source of nervous
power, it becomes
evident that this
arrangement has an
important bearing
on the mental ca-
pacity of the indi-
vidual. And it is
noticed that in
children, before the
mind is brought
into vigorous use,
these markings or
furrows on the sur-
face are compara-
tively shallow and
indistinct; the same fact is true of the brain in the less
civilized races of mankind and in the lower animals. It is
also noticeable, that among animals, those are the most
capable of being educated which have the best develop-
ment of the cerebrum. (Read Note i.)
10. The Cerebellum. The "little brain" is placed
beneath the posterior part of the cerebrum, and, like the
latter, is divided into hemispheres. Like it, also, the sur-
face of the cerebellum is composed of gray matter, and its
interior is chiefly white matter. It has, however, no con-
volutions, but is subdivided by many crescentic, parallel
ridges, which, sending down gray matter deeply into the
FIG. 41. UPPER SURFACE OP THE CEREBRUM.
A, Longitudinal Fissure.
B, The Hemispheres.
10. Location of tho "little brain ?" How divided ? Its surface and interior 1
Jts subdivisions ? Its size ?
154 THE NERVOUS SYSTEM.
white, central portion, gives the latter a somewhat branched
appearance. This peculiar appearance has been called
FIG. 42. VERTICAL SECTION OF THE BUAIN.
A, Left Hemisphere of Cerebrvfta. D, The Pone Varolii.
B, Corpus Callosum. E, Upper extremity of the Spinal Cord.
C, Optic Thalamus. F, The Arbor Vitae.
the arbor vitce, or the "tree of life," from the fact that
when a section of the organ is made, it bears some resem-
blance to the trunk and branches of a tree (Fig. 42, F).
In size, this cerebellum, or "little brain," is less than one-
eighth of the cerebrum.
/\ 11. From the under surface of the cerebrum, and from
the front margin of the cerebellum, fibres collect together
fo form the medulla oHongaia (Fig. 43, MA), which, on is-
suing from the skull, enters the spinal column, and then
becomes known as the spinal cord. From the base of the
brain, and from the sides of the medulla originate, also,
the cranial nerves, of which there are twelve pairs. These
nerves are round cords of glistening white appearance, and,
11. Medulla oblcngata Crauid- uervee? Tiieir sioaoe and oition f
THE NERVOUS SYSTEM. 155
like the arteries, generally lie remote from the surface of
the body, and are well protected from injury.
FIG. 43. THE BASE OF THE BRAIN.
12. The Spinal Cord. The 'spinal cord, or " marrow,"
is a cylindrical mass of soft nervous tissue, which occupies
a chamber, or tunnel, fashioned for it in the spinal column
(Fig. 44). It is composed of the same substances as the
brain ; but the arrangement is exactly reversed, the white
matter encompassing or surrounding the gray matter in-
stead of being encompassed by it. The amount of the
white substance is also greatly in excess of the other ma-
terial. A vertical fissure partly separates the cord into
two lateral halves, and each half is composed of two sep-
arate bundles of fibres, which are named the anterior and
posterior columns.
13. These columns have entirely different uses, and each
1 2. The spinal cord ? Of what composed ? How divided ? Each half?
13. Uses of these columns? Importance of this part of the nervous system?
How protected ?
156
THE NERVOUS SYSTEM.
PIG. 44.
A, Cerebrum.
B, Cerebellum.
D, D, Spinal Cord.
of them unites with a different
portion of the nerves which have
their origin in the spinal cord.
The importance of this part of
the nervous system is apparent
from the extreme care taken to
protect it from external injury.
For, while a very slight disturb-
ance of its structure suffices to
disarm it of its power, yet so
staunch is its bony enclosure,
that only by very severe injuries
is it put in peril. The three
membranes that cover the brain
are continued downward so as
to envelope and still further
shield this delicate organism.
14. The Spinal Nerves.
The spinal nerves, thirty -one
pairs in number, spring from
each side of the cord by two
roofs, an anterior and a poste-
rior root, which have the same
functions as the columns bear-
ing similar names. The poste-
rior root is distinguished by pos-
sessing a ganglion of gray mat-
ter, and by a somewhat larger
size. The successive points of
departure, or the off-shooting of
these nerves, occur at short and
nearly regular intervals along
the course of the spinal cord.
Soon after leaving these points,
14. The spinal nerves ? The posterior root? The nerves, uuw arranged?
Their office ?
THE NERVOUS SYSTEM. 157
the anterior and posterior roots unite to form the trunk
of a nerve, whioh is distributed, by means of branches,
to the various organs of that part of the body which this
nerve is designed to serve. The spinal nerves supply
chiefly the muscles of the trunk and limbs and the ex-
ternal surface of the body.
15. The tissue composing the nerves is entirely of the
white variety, or, in other words, the nerve-fibres; the
same as we have observed forming a part of the brain.
But the nerves, instead of being soft and pulpy, as in the
case of the brain, are dense in structure, being hardened
and strengthened by means of a fibrous tissue which sur-
rounds each of these delicate fibres, and binds them to-
gether in glistening, silvery bundles. Delicate and mi-
nutely fine as are these nerve-fibres, it is probable that
each of them pursues an unbroken, isolated course, from its
origin, in the brain or elsewhere, to that particular point
which it is intended to serve. For, although their extrem-
ities are often only a hair's breadth distant from each other,
the impression which any one of them communicates is
perfectly distinct, and is referred to the exact point whence
it came.
16. This may be illustrated in a simple manner, thus:
if two fingers be pressed closely together, and the point of a
pin be carried lightly across from one to the other, the eyes
may be closed, and yet we can easily note the precise instant
when the pin passes from one finger to the other. If the
nerve-fibres were less independent, and if it were necessary
that they should blend with and support each other, all
accuracy of perception would be lost, and all information
thus afforded would be pointless and confused. These sil-
very threads must, therefore, be spun out with an infinite
degree of nicety. Imagine, for instance, the fibre which
1 5. The nerve tissue ? Its character? Course of each nerve fibre ?
16. How may we illustrate the fact? The fibre connecting the brain with a
point in the foot ?
158 THE NERVOUS SYSTEM.
connects the brain with some point on the foot, its length
cannot be less than one hundred thousand times greatox
than its diameter ; and yet it performs its work with as
much precision as fibres that are comparatively much
Stronger and less exposed. (Read Note 7, end of Chapter.}
A IT. The Sympathetic System. The sympathetic
'system of nerves remains to be described. It consists of a
double chain of ganglia, situated on each side of the
spinal column, and extending through the cavities of the
trunk, and along the neck into the head. These ganglia
are made up for the most part of small collections of gray
nerve-cells, and are the nerve-centres of this system.
From these, numerous small nerves are derived, which
connect the ganglia together, send out branches to the
cranial and spinal nerves, and form networks in the vicin-
ity of the stomach and other large organs. A considerable
portion of them also follows the distribution of the large
and small blood-vessels, in which the muscular tunic ap-
pears. Branches also ascend into the head, and supply
the muscles of the eye and ear, and other organs of sense.
18. In this manner, the various regions of the body are
associated with each other by a nervous apparatus, which
is only indirectly connected with the brain and spinal
cord; and thus it is arranged that the most widely sep-
arated organs of the body are brought into close and
active sympathy with each other, so that, "if one member
suffers, all the other members suffer with it." From this
fact, the name sympathetic system, or the great sympathetic
verve, has been given to the complicated apparatus we have
"briefly described. Blushing and pallor are caused by men-
tal emotions, as modesty and fear, which produce opposite
conditions of the capillaries of the face by means of these
Sympathetic nerves. (Read Note 8, end of Chapter.}
\ 7. The sympathetic system of nerves ? Of what does it consist ?
18. Association of the various regions of the body ? If one member suffers ?
Rlnshinsr ?
THE NERVOUS SYSTEM. 159
19. The Properties of Nervous Tissue. We have
seen that in all parts of this system, there are only two
forms of nervous tissue ; namely, the gray substance and
the white substance, so called from their difference of color
as seen by the naked eye; or the nerve-cell, and the nerve-
fibre, so called from their microscopic appearance. Now
these two tissues are not commonly mingled together, but
either form separate organs, or distinct parts of the same
organs. This leads us to the conclusion that their respec-
tive uses are distinct. And this proves to be the simple
fact ; wherever we find the gray su bstance, we must look
upon it as performing an active part in the system, that is,
it originates nervous impulses ; the white matter, on the
contrary, is a passive agent, and serves merely as a con-
ductor of nervous influences. Accordingly, the nervous
centres, composed so largely of the gray cells, are the great
centres of power, and the white fibres are simply the in-
struments by which the former communicate with the near
and distant regions of the body under their control.
20. We may compare the brain, then, to the capital, or
seat of government, while the various ganglia, including
the gray matter of the cord, like so many subordinate
official posts, are invested with authority over the outly-
ing provinces ; and the nerves, with the white matter of
the cord, are the highways over which messages go and
return between these provinces and the local or central
governments. But both forms of nervous tissue possess
the same vital property, called excitability ; by which term
is meant, that when a nerve-cell or fibre is stimulated by
some external agent, it is capable of receiving an impres-
sion and of being by it excited into activity. A ray of
light, for example, falling upon one extremity of a fibre
in the eye, excites it throughout its whole length ; and its
1 9. Properties of nervous tissue ? Office of the gray substance ? Of the white ?
the nervous centres ? White fibres ?
20. What comparison is made between the brain and the nation's capitol ?
The vital property, excitability ? What example is given?
160 THE NERVOUS SYSTEM.
other extremity, within the brain, communicating with a
nerve-cell, the latter, in its turn, is excited, and the sensa-
tion of sight is produced. (Read Note 2.)
21. What sort of change takes place in the nervous
tissue when its excitability is aroused, is not known ;
certainly none is visible. On this account, it has been
thought by some, that the nerve-fibre acts after the man-
ner of a telegraph wire : that is, it transmits its messages
without undergoing any material change of form. But,
though the comparison is a convenient one, it is far from
being strictly applicable ; and the notion that nerve-force
is identical with electricity has been fully proved to be
incorrect.
* 22. The Functions of the Nerves. The nerves
are the instruments of the two grand functions of the
nervous system, Sensation and Motion. They are not the
true centres of either function, but they are the conductors
of influences which occasion both. If the nerve in a limb
of a living animal be laid bare, and irritated by pinching,
galvanizing, or the like, two results follow, namely: the
animal experiences a sensation, that of pain, in the part to
which the nerve is distributed, and the limb is thrown into
convulsive action. When a nerve in a human body is cut
by accident, or destroyed by disease, the part in which it
ramifies loses both sensation and power of motion ; or, in
other words, it is paralyzed. We accordingly say that the
nerves have a twofold use, a sensory and motor function.
23. If a nerve that has been exposed be divided, and the
inner end, or that still in connection with the nerve-cen-
tres, be irritated, sensation is produced, but no movement
takes place. But if the outer end, or that still connected
with the limb, be irritated, then no pain is felt, but mus-
21 . Change in the nervous tissues V Nerve force and electricity ?
22. Function* of the nerves ? In the case of the nerve of a living animal ? Of
the human body ?
23. If an exposed nerve be divided ? What is proved? The course of the sensory
fti-t of fibres ? Of the motor s a? To what are they likened 't
THE NERVOUS SYSTEM. 1G1
cular contractions are produced. Thus we prove that there
are two distinct sets of fibres in the nerves ; one of which,
the sensory fibres, conduct toward the brain, and another,
the motor fibres, conduct to the muscles. The former may
be said to begin in the skin and other organs, and end in
the brain ; while the latter begin in the nervous centres
and end in the muscles. They are like a double line of
telegraph wires, one for inquiries, the other for responses.
24. We have already spoken 01 the two roots of the spinal
nerves, called from their points of origin in the spinal
cord, the anterior and posterior roots. These have been
separately cut and irritated in the living animal, and it has
been found that the posterior root contains only sensory
fibres, and the anterior root has only motor fibres. So that
the nerves of a limb may be injured in such a way that it
will retain power of motion and yet lose sensation ; or the
reverse condition, feeling without motion, may exist. Be-
tween these two sorts of fibres, no difference of structure
can be found; and where they have joined to form a nerve
it is impossible to distinguish one sort from the other.
25. Occasionally a nerve is so compressed as to be tem-
porarily unable to perform its functions: a transient par-
alysis then takes place. This is the case when the leg or
arm "gets asleep," as it is expressed. When such is the
condition with the leg, and the person suddenly attempts
to walk, he is liable to fall, inasmuch as the motor fibres
cannot convey orders to the muscles of the limb. Another
fact is observed : there is no sensation in this nerve at the
point of its compression ; but the whole limb is numb, and
tingling sensations are felt in the foot, the point from
which the sensory fibres arise.
26. This illustrates the manner in which the brain in-
24. The two roots of the spinal nerves ? What ha? been found ? Difference
of the two sorts of fibres ? Result of their union *
25. Transient paralysis? When such is the case with the leg? What other
fact is observed ?
26. What does this illustrate ? Sensation ? The feeling after a limb has been
amputated ? Striking of the " funny bone ?"
162 THE NERVOUS SYSTEM.
terprets all injuries of the trunk of a nerve. Sensation or
pain is not felt at the point of injury, but is referred to the
outer extremities of the nerve, where impressions are habit-
ually received. This is the reason why, after a limb has
been amputated by the surgeon, the patient appears to
suffer pain in the member that has been severed from the
body; while some form of irritation at the end of the nerve
in the wound, or stump, is the real source of his distress.
Again, when the "funny-bone" that is, the ulnar nerve
at the elbow, is accidentally struck, the tingling sensa-
tions thus produced are referred to the outer side of the
hand and the little finger, the parts to which that nerve is
distributed.
27. All the spinal nerves, and two from the brain, are
concerned in both sensation and motion. Of the remainder
of the cranial nerves, some are exclusively motor, others
exclusively sensory; and still others convey, not ordinary
sensations, but special impressions, such as sight, hearing,
and smell, which we have yet to consider. However much
the functions of the nerves seem to vary, there is but little
difference discoverable in the nerves themselves, when ex-
amined under the microscope. Whatever difference exists
must be accounted for in consequence of the nerves com-
municating with different portions of the gray matter of
the brain. The rate of motion of a message, to or from
the brain along a nerve, has been measured by experi-
ment upon the lower animals, and estimated in the case of
man at about two hundred feet per second. As compared
with that of electricity, this is a very slow rate, but, in
respect to the size of the human body, it is practically in-
stantaneous. (Read Note 3.)
28. The Functions of the Spinal Cord. As the
27. The spinal nerves, and two from the brain ? Of the remainder? Difference
in the nerves ? How accounted for ? The rate of conduction along a nerve ? As
compared with electricity?
28. Functions of the'anterior and posterior columns of the cord ? If the cord
be divided?
THE NERVOUS SYSTEM. 163
anterior and posterior roots of the spinal nerves have sepa-
rate functions, so the anterior and posterior columns of
the cord are distinct in function. The former are con-
cerned in the production of motion, the latter in sensation.
If the cord be divided, as before in the case of the nerve, it
is found that the parts below the point of injury are de-
prived of sensation and of the power of voluntary motion
on both sides of the body, a form of paralysis which is
called paraplegia.
29. This form of disease, paraplegia, is sometimes seen
among men, generally as the result of a fall, or some other
severe accident, by which the bones of the spine are broken,
and the cord is crushed, or pierced by fragments of bone.
The parts which are supplied by nerves from the cord
above the point of injury are as sensitive and mobile as
before. The results are similar, whether the division hap-
pens at a higher or lower portion of the spinal cord ; but
the danger to life increases proportionally as the injury
approaches the brain. When it occurs in the neck, the
muscles of inspiration are paralyzed, .since they are sup-
plied by nerves issuing from that region ; and as a result
of this paralysis, the lungs are unable to act, and life is
speedily brought to a close.
30. When the spinal cord of an animal has been cut, in
experiment, it may be irritated in a manner similar to that
alluded to when considering the nerves. If, then, the
upper cut surface be excited, it is found that pain, refer-
able to the parts below the cut, is produced ; but when the
lower cut surface is irritated, no feeling is manifested. So
we conclude that in respect to sensation, the spinal cord is
not its true centre, but that it is merely a conductor, and
is therefore the great sensory nerve of the body. When
the lower surface of the cut is irritated, the muscles of the
20. Paraplegia? Result and danger to life? When the injury occurs in the
neck ?
3O. Experiment of cutting the spinal cord ot an animal ? What inference is
dra ,vn ?
164 THE NERVOUS SYSTEM.
parts below the section are violently contracted. Hence,
we conclude that, in respect to the movements ordered by
the will, the spinal cord is not their source ; but that it
acts only as a conductor, and is, accordingly, the great
motor nerve of the body.
31. Direction of the Fibres of the Cord. If one
lateral half of the spinal cord be cut, or injured, a very sin-
gular iact is observed. All voluntary power over the mus-
cles of the corresponding half of the body is lost, but the
sensibility of that side remains undiminished. This result
seems to show that the motor fibres of the cord pursue a
direct course, while its sensory fibres are bent from their
course. And this has been proved to be the fact; for im-
mediately after the posterior roots the conductors of sen-
sory impressions join the posterior columns, they enter
the gray matter of the cord, and passing over, ascend to the
brain on the opposite side. Accordingly, the sensory fibres
from the right and left sides interlace each other in the
gray matter; this arrangement has been termed the decus-
sation, or crossing of these fibres. This condition serves
to explain how a disease or injury of the cord may cause a
paralysis of motion in one leg, and a loss of sensation in
the other.
32. The direction of the anterior, or motor columns of
the cord, is downward from the brain. In the cord itself,
the course of the motor fibres is for the most part, a direct
one; but in the medulla oblongata, or upper extremity of
the cord, and therefore early in their career, these fibres
decussate, or cross from side to side in a mass; and riot
separately, as in the case of the posterior fibres just men-
tioned. This arrangement is termed the decussation of
the anterior columns of the medulla.
33. From this double interlacing of fibres results a
3 1 . What singular fact is noticed ? What does the result show ?
32. Direction of the anterior or motor columns? In the cord itself? In the
medulla oblongata ? The decussation ?
33. Result of the double interlacing of fibres? Where is the seat of paiu
THE NERVOUS SYSTEM.
crossed action between the original and terminal extremity
of all nerve-fibres which pass through the medulla ;
namely, those of all the spinal nerves. Consequently, if
the right hand be hurt, the left side of the brain feels the
pain ; and if the left foot move, it is the right hemisphere
which dictates its movement. For the same reason, when
a loss of sensation and power of motion affecting the right
side of the body alone is observed, the physiologist under-
stands that the brain has been invaded by disease upon its
left side. This affection is termed Jiemiplegia y or the " half-
stroke." The full-stroke, which often follows the rupture of
a blood-vessel in the brain, is commonly called paralysis.
34. The Reflex Action of the Cord. We have
already considered the cord as the great motor and sensory
nerve of the body, but it has another and extremely impor-
tant use. By virtue of the gray matter, which occupies
its central portion, it plays the part of an independent
nerve centre. The spinal cord not only conducts some
impressions to the brain, but it also arrests others; and, as
it is expressed, " reflects" them into movements by its own
power. This mode of nervous activity is denominated the
Reflex Action of the cord.
35. A familiar example of this power of the cord is
found in the violent movements which agitate a fowl
after its head has been cut off. The cold-blooded animals
also exhibit reflex movements in an astonishing degree.
A decapitated centipede will run rapidly forward, and will
seemingly strive to overturn, or else climb over obstacles
placed in its way. A frog similarly mutilated will sustain
its headless body upon its feet, in the standing posture,
just as it might do if it were still alive. If pushed over,
it will regain its feet; and if the feet are irritated, it will
when the right hand is hurt ? The moving of the foot ? Loss of sensation it, one
side of the body ?
34. What other important use has the cord? What is the activity denomi
aated ?
3 5 . Example of the fowl ? Centipede ? Prog ? What dc they prove ?
ICG THE NERVOUS SYSTEM.
jump forward. There can be no doubt that, in the lower
animals, movements may take place which are completely
divorced from the will, sensation, and consciousness; for
in those animals, as well as in man, these faculties have
their principal seat within the brain.
36. An irritation is necessary, in most instances, to
awaken reflex movements. In the case of the decapitated
fowl, its muscles are excited to convulsive action by
reason of its being thrown upon the hard ground and
roughly handled. Let it be treated differently, and the
convulsions will not take place : let it be laid gently upon
soft cotton, and the body will remain comparatively quiet.
It may comfort some people to know that the convulsions
which follow decapitation are not attended with pain ; nor
are they a necessary part of the " act of death," as some
suppose.
37. In the human body, likewise, actions are excited
that are entirely distinct from the ordinary voluntary
efforts. It is not permissible, desirable, nor even necessary
to decapitate a man that the body may be disconnected
from his brain, in order to test the effect of irritation upon
the spinal cord; although the bodies of beheaded crimi-
nals have been experimented upon, and caused to move by
powerful galvanic batteries. The resort to such means of
experiment is rendered unnecessary by the occurrence of
certain deplorable cases of disease and injury, which effect-
ually sever all communication between the brain and a
large part ot the body.
38. Thus, the cord may be so far injured, as the result
of accident, as to terminate all sensation and voluntary
motion in the lower half of the body, the patient seem-
ingly becoming lifeless and powerless from the waist down-
ward. And yet, by tickling or pinching either foot, the leg
36. What is necessary in most cases to awaken reflex movements? In the
Case of the fowl ? Convulsion!* which follow decapitation ?
37. Actions in the human body distinct from voluntary effort* ?
38. Reflex action after injury of the cord? Why not due to the muscles t
THE KEKVOUS SYSTEM. 167
of the same side may be made to jerk, or even to kick with
considerable force; but, unless the patient is observing his
limbs, he is wholly unconscious of these movements, which
are, therefore, performed independently of the brain. And
they are in nowise due to the muscles of the limb; for,
if the cord itself becomes diseased below the point of in-
jury, the muscles cease to contract.
39. For the production of this form of nervous action*
three things are requisite (1) a nerve to conduct messa-
ges from the surface of the body, one of that variety for-
merly described as sensory, but which are now incapable of
awakening sensation ; (2) a portion of uninjured spinal
cord which shall reflect or convert impressions into im-
pulses; and (3) a motor nerve to conduct impulses outward
to the muscles. The power of the cord to enforce reflex
acts resides in the gray matter, into which the reflex nerves
enter and from which they depart, by means of their pos-
terior and anterior roots respectively.
40. The Uses of the Reflex Action. The reflex
activity of the cord is exhibited in the healthy body in
many ways, but since it is never accompanied with sensa-
tion, we do not readily recognize it in our own bodies.
Eeflex movements are best studied in the cases of other
persons, when the conditions enable us to distinguish
between acts that are consciously, and those that are un-
consciously performed. For example, if the foot of a per-
son soundly asleep be tickled or pinched, it will be quickly
withdrawn from the irritation.
41. Similar movements may be observed in cases where
the consciousness and sensation are temporarily obliter-
ated by disease, or by means of narcotic poisons. If the
arm of a person who has been rendered insensible by
39. What arc the requisites for the production of this form of nervous action?
40. Whv do we not readily recotjnize the reflex activity of the cord in our own
bodies ? How best studied in others ? Example ?
4 1 . Similar movements ? Arm of a oerson ? Melted wax or heated coin on the
hand?
168 THE NERVOUS SYSTEM.
chloroform, be raised, and then allowed to fall, it will be
noticed that the limb does not drop instantly, like a life-
less member, but a certain amount of rigidity remains in
its muscles, which resists or breaks the force of its descent.
Again, when a substance like melted sealing-wax, or a
heated coin, falls upon the hand, the limb is snatched
away at once, even before the feeling of pain has been
recognized by the brain. When jolted in a rapidly moving
car, we involuntarily step forward or backward, so as to
preserve the centre of gravity of the body.
42. These and similar acts are executed by the same
mechanism as that previously described in the case of
paralysis from an injury of the spinal cord. The muscles
thus called into play, are those which are ordinarily under
the sway of the will, but which in these cases act through
this reflex action of the cord, altogether independently of
the will. A healthful reflex activity produces an elasticity,
or " tone," of the voluntary muscular system, which, in a
great measure, explains the existence in the young and
vigorous of a feeling of buoyancy and reserve power. Its
possessor is restlessly active, and it may appropriately be
said of him, " he rejoiceth as a strong man to run a race."
But this reflex energy may be deficient. This is true when
the blood is poor and wanting in its solid ingredients, or
the circulation is feeble ; the muscles, then, are flabby and
weak, and the person himself is said to be " nerveless," or
indisposed to exertion. Shivering from cold, and trem-
bling from fear, may, in part, be referred to a temporary
loss of tone, resulting from a powerful impression upon the
brain, (Read Note 9, end of Chapter)
43. An excess of this activity may also be observed in
disease. In this condition, the excitability of the cord is
unnaturally aroused, and frequent and violent movements
41. Result of healthful reflex activity ? When may the reflex energy he defi-
cient ?
43. Excess of this activity 'n disease ? Hydrophobia, etc, ? The difference IE
severity of the convulsions "
THE NERVOUS SYSTEM. 169
of the limbs and body, called convulsions, are the result.
The convulsions of young children, and the nervous agita-
tion of chorea, or St. Vitus's dance, are reilex in character ;
as are also the symptoms attending poisoning by strychnine,
and those terrible diseases, tetanus, or " locked jaw," and
hydrophobia. The severity of the convulsions is not the
same in all cases of these disorders ; but, in those last men-
tioned the most violent spasmodic movements are provoked
by the slightest form of irritation such as the sound of
pouring water, the sight of any glittering object, the glanc-
ing of a mirror, the contact of cool air, or even the touch
of the bedclothes.
44. Another variety of reflex motions takes place in cer-
tain involuntary muscles, and over these the cord exercises
supreme control. They are principally those movements
which aid the performance of digestion and nutrition, the
valve-action of the pylorus, and other movements of the
stomach and intestines. In these movements the mind
shares no part. And it is well that this is so ; for since
the mind is largely occupied with affairs external to the
body, it acts irregularly, becomes fatigued, and needs fre-
quent rest. The spinal cord, on the contrary, is well fitted
for the form of work on which depends the growth and
support of the body, as it acts uniformly, and with a ma-
chine-like regularity.
45. These operations are not accompanied by conscious-
ness; for, as a general rule, the attention is only called to
them when they become disordered. Many a person does
not know where his stomach is situated, until he discovers
'its position by reason of a feeling of distress within it,
produced by giving that organ improper work to perform.
In this manner the higher and nobler faculties of the
mind are liberated from the simply routine duties of the
44. Another variety of reflex motions ? What are they? What is stated of the
mind in connection with these movement? ?
45. Consciousness in these operations? Physical wants ?
170 THE NERVOUS SYSTEM.
body; and we are thus left to direct the attention, the rea-
son, and the will to the accomplishment of the great ends
of our existence. If it were otherwise, we could only find
time to attend to our ordinary physical wants.
46. The objects of the reflex activity of the cord are
threefold. In the first place, it acts as the protector of man,
in his unconscious moments. It is his unseen guardian,
always ready to act, never growing weary, and never re-
quiring sleep. Nor does its faithful action wholly cease
with the cessation of life in other parts. In the second
place, it is the regulator of numerous involuntary motions
that are necessary to the nutrition of the body. Here its
actions are entirely independent of the brain, and are per-
formed in a secret and automatic manner. And. thirdly, it
acts as a substitute, and regulates involuntary movements
in the muscles usually under the influence of the will. It
thus takes the place of the higher faculties in performing
habitual acts, and permits them to extend their operations
more and more beyond the body and its material wants.
A 47. The Functions of the Medulla Oblongata.
The prolongation of the spinal cord, within the skull,
has been previously spoken of as the medulla oblongata.
It resembles the cord, in being composed of both white
and gray matter, and in conducting sensory and motor in-
fluences. It likewise gives rise to certain nerves, which are
here called cranial nerves (from cranium, the skull). All
except two of these important nerves spring from the me-
dulla, or the parts immediately adjoining it ; the exceptions
are the two nerves taking part in the special senses of sight
and smell, which nerves have their origin at the base of
the cerebrum.
48. The decussation, or crossing of the motor columns,
has been previously described, when treating of the direc-
46. How many objects may the reflex activity be said to have ? State the first
The second. The third.
47. How does the medulla oblongata resemble the cord ?
48. What final fact ia observed in the crowing of the motor columns ?
THE NERVOUS SYSTEM. 171
tion of the nerve-fibres of the cord; and the singular fact
has been alluded to, that when one side of the brain is
injured, its effects are limited to the opposite side of the
body. One more fact remains to be observed in this con-
nection, namely, this crossed action does not usually take
place in the cranial nerves. Accordingly, when apoplexy,
or the rupture of a blood-vessel, occurs in the right hemi-
sphere of the cerebrum, the left side of the body is paralyzed,
but the right side of the face is affected ; this is because
that part of the body is supplied by the cranial nerves.
49. A portion of the medulla presides over the impor-
tant function of respiration, and from it arises the pneu-
mogastric nerve, so called because its branches serve both
the lungs and stomach. The feelings of hunger, thirst,
and the desire for air are aroused by means of this nerve.
The wounding of the gray matter of the medulla, even of
a small portion of it, near the origin of the pneumogastric
nerve, at once stops the action of the lungs and causes
death. In consequence of the importance of this part, it
has been termed the "vital knot." We find, also, that its
location within the skull is exceedingly well protected, it
being quite beyond the reach of any ordinary form of
harm from without.
50. The Functions of the Cranial Ganglia. The
uses of the smaller gray masses lying at the basv. of the
brain are not well ascertained ; and, on account of their
position, so remote from the surface, it would, at first, seem
well-nigh impossible to study them. But, from the results
following diseases in these parts, and from experiments
upon inferior animals, they are becoming gradually better
understood; and there is reason to believe that eventually
the physiological office of each part will be clearly ascer-
tained and defined. It is believed, however, but not abso-
49. The pneumogastric nerve ? The feelings aroused by it ? The '" vital
knot?"
50. The uses of the smaller gray masses at the base of the brain ?
172 THE NERVOUS SYSTEM.
iutely proven, that the anterior masses, like the anterior
roots of the spinal nerves and the anterior columns of
the cord, are concerned in the production of motion; in
fact, that they are the central organs of that function.
The posterior gray masses are, on the contrary, supposed
to be the seat of sensation.
51. The Function of the Cerebellum. The func-
tion of the cerebellum, or " little brain,' 7 is the direction
of the movements of the voluntary muscles. When this
organ is the seat of disease or injury, it is usually observed
that the person is unable to execute orderly and regular
acts, but moves in a confused manner as if in a state of
intoxication. Like the larger brain, or cerebrum, it
appears to be devoid of feeling; but it takes no part in
the operations of the mind.
i 52. The Function of the Cerebrum. The cere-
brum, or brain proper, is the seat of the mind; or, speak-
ing more exactly, it is the material instrument by which
the mind acts; and, as it occupies the highest position in
the body, so it fulfils the loftiest uses. All the other
organs are subordinate to it: the senses are its messengers,
which bring it information from the outer world, and the
organs of motion are its servants, which execute its com-
mands. Here, as in the nervous apparatus of lower grade
already considered, the gray matter is the element of
power; and, in proportion as this substance increases in
extent, and in proportion to the number of convolutions
in the hemispheres, do the mental faculties expand. *
53. There have been a few, but only a few, men of dis-
tinguished ability whose brains have been comparatively
small in size ; the rule being that great men possess large
brains. The relative weight of the brain of man, as com-
5 1 . Function of the cerebellum ? When it is diseased ?
52. Where i? the seat of the mind? The subordination of the other orgcins .
The gray matter ?
53. What is stated of men in connection with the size of their brain ? With
the brains of other animals ?
(* RwdNqte 10, end of Ch
THE KEBYOUS SYSTEM. 173
pared with the weight of the body, does not, in all instan~
ces, exceed that of the inferior animals ; the canary and
other singing-birds have a greater relative amount of nerv-
ous matter than man ; but man surpasses all other crea-
tures in the size of the hemispheres of the cerebrum, and
in the amount of gray substance which they contain. *
54. It is a singular fact that this cerebral substance is
insensitive, and may be cut without causing pain. The
removal of a considerable quantity of the brain has taken
place, as the result of accident, without causing death, and
without even affecting seriously the intellect. A remark-
able case of injury of the brain is recorded, in which,
from the accidental explosion of gunpowder used in blast-
ing a rock, the " tamping-iron" was driven directly through
the skull of a man. This iron rod, three feet and seven
inches long, an inch and a quarter in diameter, and weigh-
ing more than thirteen pounds, entered the head below the
ear and passed out at the top of the skull, carrying with it
portions of the brain and fragments of bone. The man
sustained the loss of sight on one side, but otherwise
recovered his health and the use of his faculties. More-
over, disease has occurred, compromising a large portion
of the brain, without impairing the faculties of the mind,
when the disease was limited to one side only.
55. Impressions conveyed to the hemispheres from the
external world arouse the mental operations called
thought, emotion, and the will. These are the god-
like attributes which enable man to subjugate a world,
and afterward cause him to " sigh for other worlds to con-
quer;" which enable him to acquaint himself with the
properties of planets millions of miles distant from him,
and which give him that creative power by which he
builds and peoples the new worlds of poetry and art.
54. Sensitiveness of the brain substance? The removal of a portion of the
Irain ? State the remarkable case mentione i ?
55, Thought, emotion, and will ? What power do they give us?
(* Read Not? n, end of Chapter.)
174 THE NERVOUS SYSTEM.
56. All these mental acts, and many others, are devel-
oped through the action of the brain ; not that the brain
and the mind are the same, or that the brain secrete
memory, imagination, or the ideas of truth and justice, as
the stomach secretes the gastric juice. But rather, as the
nerve of the eye, stimulated by the subtile waves of light,
occasions the notion of color, so the brain, called into
action by the mysterious influences of the immaterial soul,
gives rise to all the intellectual, emotional, and voluntary
activities of mankind. (Read Note 5)
57. The cerebrum, according to our present knowledge
of it, must be regarded as a single organ, which producer
different results, according as it is acted upon by the im-
material mind in different ways. Recent investigations,
however, seem to prove that the faculty of language is de-
pendent upon a small part of the left hemisphere of the
cerebrum, near the temple. At least, in almost every
instance where this part is diseased, the patient can no
longer express himself in speech and writing.
58. The Reflex Action of the Brain. The reflex
function of the organs within the skull is very active and
important. Like that of the cord, it protects the body by
involuntary movements, it regulates the so-called vegeta-
tive acts, and it takes the place of the will in controlling
the voluntary muscles, when the attention is turned in
other directions. The reflex power of the medulla governs
the acts of respiration, which are absolutely and continu-
ously essential to life. Eespiration is, as we have seen,
partly under the influence of the will; but this is due in
part to the fact that respiration is indirectly concerned in
one of the animal functions, that of speech.
59. Reflex action also occasions coughing and sneezing,
56. Are the brain and the mina identical ?
57. What do we know of the cerebrum and its powers ?
58. The reflex function of the organs within the skull? The reflex power of
the medulla ? Respiration ?
59. What else does reflex action occasion ? Winking? Other examples ?
THE NERVOUS SYSTEM. 175
whenever improper substances enter the air-passages.
Winking is an act of the same sort, and serves both to
shield the eyes from too great glare of light, and to pre-
serve them by keeping the cornea moist. Looking at the
sun or other strong light, causes sneezing by reflex action.
Laughing, whether caused by tickling the feet or by some
happy thought, and also sobbing, are reflex acts, taking
place by means of the respiratory muscles.
60. Certain of the protective reflex movements call into
play a large number of muscles, as in the balancing of the
body when walking along a narrow ledge, or on a slippery
pavement. The dodging motion of the recruit, when the
first cannon ball passes over his head, is reflex and invol-
untary. The fact that these involuntary, reflex acts are
performed with great precision, will explain why it is that
accidents seldom befall the somnambulist, or sleep-walker,
although he often ventures in most perilous places.
61. Walking, sitting, and other acts of daily life, be-
come automatic, or reflex, from habit : the mind is seldom
directed to them, but delegates their control to the medulla
and spinal cord. Thus a person in walking, may traverse
several miles while absorbed in thought, or in argument
with a companion, and yet be conscious of scarcely one in
a thousand of the acts that have been necessary to carry
his body from one point to another. By this admirable
and beautiful provision, the mind is released from the
charge of the ordinary mechanical acts of life, and may
devote itself to the exercise of its nobler faculties. And if
is worthy of notice, that the greater the use of these facul-
ties, the more work does the reflex function assume and
perform ; and thus the employment of the one insures the
improvement of the other. (Read Note 6.)
60. Musclep called Into play by certain reflex movements ? The somnambulist ?
61. What is said of walking and other acts in connection with the office per
formed by the medulla and spinal cord ?
176 REVIEW QUESTIONS.
QUESTIONS FOR TOPICAL REVIEW.
PAGE
1. State fully what is meant by the term vegetable function 148
2. To what is man indebted for his position as the head of the animal crea-
tion ? 148, 149
3. What can you state on the subject of special organs for separate functions ? 149
4. Describe, as fully as you can, the structure of the nervous system 149, 150
5. Describe the brain, its location, size, shape, and structure 150, 152
6. Describe the brain proper, or cerebrum 152, 153, 174
7. What connection is noticed between the cerebrum and mental
power? 153, 172,174
8. Describe the little brain, or cerebellum 153, 154, 172
9. Describe the spinal cord 154, 155,156
10. What are the spinal nerves, and how are they arranged ? 156, 157
11. What is the character and substance of their tissues ? 157
12. State how the nerve-fibres perform their office, and give the illustra-
tion 157,158
13. Describe the sympathetic system of nerves 158
14. State what is meant by the properties of nervous tissue, and give the
illustration 159, 160
15. Explain what is meant by the functions of the nerves, and give the
illustration 160,161,162
16. What is meant by a transient paralysis of a nerve ? Give the illustra-
tion 161,163
17. What can you state of the rate of message-motion along a nerve ? 162
18. What are the functions of the spinal cord ? 162, 163, 164, 165
19. State what you can of the form of paralysis known as paraplegia 162
20. What experiments, with results, upon the spinal cord are noted ? 163, 164
21. Explain how injury of the cord may produce paralysis of motion in one
leg, and at the same time a loss of sensation in the other 104
22. Explain how, if the right hand be hurt, the left side of the brain is made to
feel the pain 165
23. Now, explain as fully as you can the direction of the fibres of the cord. 164, 165
24. What is understood by the reflex action of the cord ? 165
25. What experiments are mentioned to prove this power of the cord ? . . . . 165, 16(5
26. What are the uses of the reflex action of the cord ? 167-170
27. What illustrations are mentioned to show such uses ? 167-170
28. What is the medulla oblongata ? 154, 170
29. What are the functions of the medulla oblongata ? 170, 171
30. What can you state of the functions of the cranial ganglia ? 171, 172
31. What are the functions of the cerebellum ? 172
32. What is the function of the cerebrum ? 172, 174
33. lu what way does the size of tne brain generally indicate the character
of the man? 172,173
34. What facts show that the gray substance of the brain is insensitive '( 173
35. Upon what does the faculty of language seem to depend ? 174
36. What has been observed in support of this statement ? 174
37. Of what importance is the reflex action of the brain ? 174, 175
?8. In what ways is this importance made manifest ? 174, 175
NOTES.
1. The Brain (p. 153, T9). "Our brains are seventy-year clocks. The
Angel of Life winds them up once for all, then closes the case, and gives the
key to the Angel of the Resurrection. Tic-tac ! tic-tac ! go the wheels of thought ;
our will cannot stop them; they cannot stop themselves ; sleep caunot stop them ;
madness only makes them go faster ; death alone can break into the case, and,
seizing the ever-swinging pendulum, which we call the heart, silence at last the
clicking of the terrible escapement we have carried so long beneath our wrinkled
foreheads. * * * Now, when a gentleman's brain is ill- regulated or empty % it
is, to a great extent, his own fault, and so it is simple retribution that, while he
lies slothfully sleeping or aimlessly dreaming, the fatal habit settles on him like
a vampire and sucks his blood, fanning him all the while with its hot wings into
deeper slumber or idler dreams." Holmes' The Autocrat of the Breakfast- Table.
2. The Relations of the Brain and Sympathetic Nerve (p. 160,
T 20). ''Buried in the hidden recesses of the body, between the spinal column
and the great organs of nutrition, there is a double row of small knots of
nervous substance, bound together by a series of nerves running from one
to another, in succession, from the neck to the base of the column. The
whole appears like a long, fine cord, with knots at various distances a
collection of little brains, if I may use a rather crude expression. It is, as
the Swiss would say, the 'great council' of this federative republic, which
counterpoises that cerebral royalty within us. It has been well named the
great sympathetic nerve, and this it is which makes the laws by which our
interior life is governed. The nutritive apparatus of a country, its commerce,
its industry, the incessant labor of its citizens by which the public wealth is built
up and let us also add, the throbs of a national heart all this the sympathetic
system full plainly shows us requires to be left to itself. It would be a fine affair
if the brain had to watch over the service of the stomach, or if, at its conven-
ience, it regulated the movements of the master who disposes of its life. Besides,
what would become of the poor body, if the least drowsiness attacked the uni-
versal centre ? Happy is it for us and let us not be slow to own it that nature has
armed herself against these encroachments of power." MacPs The Little Kingdom
3. The Speed of Sensation and Thought (p. 162, 127). "The
rate of nervous and mental action is not the same in all individuals. In com-
paring the records made by astronomers, it has been found that an appreciable
difference exists in the rapidity with which the same occurrence may be noted by
different observers. This is known as the 'personal equation, 1 and is allowed for
With the greatest nicety in the making up of astronomical reports. With very
delicate apparatus for marking time, the various nervous impulses have been
observed; from forty to a hundred feet in a second are the estimates of different
experiments as to the speed of sensation; or, as it has been expressed, it would
take a full grown whale a second to feel the stroke of a harpoon in his tail."
4. The emotion* Influence the Bodily Health (p. 173, t 5').
"The exciting emotions which are pleasurable, such as joy and hope, are of a kind
that seldom tend to a dangerous excess, and may be regarded as exercising gener-
ally an eminently healthful influence upon the body. Hilarity i.s a great refresher
and strengthener of life. Laughter is a wholesome exercise, which, beginning
at the lungs, diaphragm, and connected muscles, is continued to the whole body,
' shaking the sides,' and causing that jelly-like vibration of the frame of which,
we are so agreeably conscious when under its influence. The heart beats more
briskly, but with a safe regularity of action, and send* the blood to the smallest
and most distant vessel. The face glows with warmth and color, the eye bright-
ens, and the temperature of the whole body is moderately raised. With the
Universal pleasurable sensation there comes a disposition of every organ to
NOTES.
healthy action. When hilarity and its ordinary expression of laughter become
habitual, the insensible perspiration of the skin is increased, the breathing quick-
ened, the lungs and chest expanded, the appetite and digestion strengthened,
and nutrition contequently increased. The old proverb, ' Laugh and grow fat,'
states a scientific truth. The influence of laughter upon the body is recognized
by Shakspere, in his description of the 'spare Cassius'' Seldom he smiles.'
'To be free-minded and cheerfully disposed at hours of meat, and sleep and
exercise, is one of the best precepts of long-lasting.' Such is the testimony of
Lord Bacon to the favorable influence of the pleasurable emotions upon the body.
The depressing emotions, such as fear, anxiety, and grief, are always fatal to
health, and frequent causes of death. There is an Eastern apologue which describes
a stranger on the road meeting the Plague coming out of Bagdad. * You have
been committing great havoc there,' said the traveller, pointing to the city. 'Not
so great! ' replied the Plague. 'I only killed one-third of those who died ; the
other two-thirds killed themselves with fright.' "The, Book of Health.
5. Mental Exercise necessary to Perfect Health (p. 174, t 56).
"The improvement of the memory is a familiar instance of an increase of
mental power produced by exercise ; and the beating sense of fulness and quick-
ened circulation in the head induced by intense study or thought, shows that
an organic process goes on when the brain is in activity, similar to that which
takes place in the muscular system under exercise. On the contrary, when the
org^n is little used, little expenditure of its power and substance takes place,
little blood and little nervous energy are required for its support, and, therefore,
little is sent: nutrition in consequence soon becomes languid, and strength im-
paired. To all these laws the brain is subject equally as the rest of the body.
Frequent and regular exercise gives it increased susceptibility of action, with
power to sustain it, the nervous energy acquiring strength as well as the vascular.
Disuse of its functions, or, in other words, inactivity of intellect and of feeling,
impairs its structure, and weakens the several powers which it serves to manifest.
The brain, therefore, in order to maintain its healthy state, requires to be duly
exercised." Barlow on Physical Education.
6. Automatic Action of the Brain (p. 175, 1"61). "A large part of
our mental activity consists of this unconscious work of the brain. There are
many cases in which the mind has obviously worked more clearly and more suc-
cessfully in this automatic condition, when left entirely to itself, than when we
have been cudgeling our brains, so to speak, to get the solution. An instance,
well authenticated, is related of a college student ; he had been attending a
class in mathematics, and the professor said to his students one day: 'A
question of great difficulty has been referred to me by a banker a very com-
plicated question of accounts, which they have not themselves been able to
bring to a satisfactory issue, and they have asked my assistance. T have been
trying, and I cannot resolve it. I have covered whole sheets of paper with calcu-
lations, and have not been able to make it out. Will you try ? ' He gave it to them
as a sort of problem, and said he would be extremely obliged to any one who would
bring him the solution by a certain day. This gentleman tried it over and over
again ; he covered many slates with figures, but did not succeed. He was ' put on
his mettle,' and determined to achieve the result. But he went to bed on the night
before the solution was to be given in, without having succeeded. In the morning,
when he went to his desk, he found the whole problem worked out and in his own
hand. He had risen in the night and unconsciously worked it out correctly, as the
result proved ; and what is more curious still, the process was very much shorter
than any of his previous trials." W. B. Carpenter on Unconscious Action.
7. How Bodily Sensations are Located (p. 158, T 16.) "A nervous
fibre which ends in the skin forms, as far as its union with the brain or cord is
concerned, one long, fine, unbroken thread. The fibres, thus ending in the skin,
very soon join to form small branches and finally in thick nerve-trunks, but in no
case do two nerve fibres coalesce so as to lose their identity. Every part of the
skin has its own separate connections with the centre of the nervous system, which
unite there just as telegraph wires unite at a terminus. The brain is the terminus
of these lines of nerves, and, as it were, receives and explains the messages sent
to it. It distinguishes very clearly by what particular fibre such a message h;;s
come, and just as the clerk in a telegraph office, where a great many wires meet
from all sides, knows by experience from what direction each wire brings its mes-
sage, so the brain aiso knows by experience what part of the skin is involved
when a sensation reaches it along a certain nerve-fibre. It is probable that the
brain, by its imaginative faculty, has formed a complete picture of the surface of
the body ; a kind of chart slowly made and always being more highly perfected,
by means of which, with each impression from without, there arises in the brain
a picture of the spot upon the skin where the irritation has taken place. Now, if
an irritation were to pass from one nerve fibre to another, it is very plain, the
brain could not tell the place from which it came, and could not localize impres-
sions received from the world about MS " Bernstein 1 s Five Senses of Man.
S. The Wonderful Operations of the Sympathetic System.
Blushing or " Shame-redness " (p. 158, ^ 18). "A blow upon the head
will knock a man senseless, but he still lives and survives ; a blow of like vio-
lence upon the pit of the stomach is followed by instant death, because the
great centre of the organic nerves lies there, and the vital actions are suspended by
the blow, so that the system never lives to recover, but abolition of function and
of life at once follows. Other actions also belong to this organic nervous system.
It controls the calibre of the blood-vessels, for which end filaments run along each
of them. The body temperature is maintained by the production and dispersion
of heat thus regulated, a continuous oscillation going on betwixt the internal ves-
sels and those of the skin. It is connected with the emotions ; and so the heart
beats perceptibly with excitement, and the maiden's cheek blushes before words
that should never be spoken or thoughts that should never arise. The momentary
dilatation of the vessels of the skin constitutes the blush, in the German, 'shame-
redness,' which is not confined to the face, though of course it is only seen there,
the body being hid by the clothes." Fotkergill on the Maintenance of Health.
There is an old tradition that when the executioner of Charlotte Corday lifted
her severed head high in air, and smote the face with his hand, the cheeks were
seen to resent the insult with a blush. This reddening is not impossible, for a
decapitated head certainly may exhibit, for a time, certain reflex movements.
But whether sensibility is retained cannot be known.
9. On Nervous, Health, or Tone (p. 168, t 42). " That state of general
vigor, which we call 'tone,' depends upon the healthy action of the nervous
centres. It consists in the habitual moderate contraction of the muscles, due to a
constant stimulus exerted on them by the cord, and is valuable less for itself, than
as a sign of a sound nervous balance. Tone is maintained partly by healthful im-
pressions radiated upon the spinal cord through the nerves from all parts of the
body, and partly by the simulus poured down upon it from the brain. So it is dis-
turbed by whatever conveys irritating or depressing influences in either direction.
A single injudicious meal, a single sleepless night, a single passion or piece of bad
news, will destroy it. On the other hand, a vivid hope, a cheerful resolve, an
absorbing interest will restore it as if by magic. For in man, these lower officers
in the nervous hierarchy draw their very breath according to the bidding of the
NOTES.
higher powers. But the dependence of the higher on the lower is no less direct.
The mutual action takes place in each line. A chief condition of keeping the
brain healthy is to keep these unconscious nervous functions in full vigor, and in
natural alternations of activity and repose. We see evidence of this law in the
delightful effect of a cheerful walk after a depressed or irritated state of mind.
Every part of the nervous system makes its influence felt by all the rest. A sort
of constitutional monarchy exists within us ; no power in this small state is abso-
lute, or can escape the checks and limitations which the other powers impose.
Doubtless the Brain is King, but Lords and Commons have their seats below and
guard their privilege with jealous zeal. If the k constitution ' of your personal
realm is to be preserved intact, it must be by the efforts of each part, lawfully
directed to a common end." Hinton on Health and its Conditions.
10. The Alliance of Mind and Body (p. 172, 1 52.) "The regular
routine of our daily life is the counterpart of the mental routine. A healthy man
wakens in the morning with a flush of spirits and energy ; his first meal confirms
and re-inforces the state. The mental powers and susceptibilities are then at a
maximum ; as the nutrition is used up in the system they gradually fade, but may
be renewed once and again by refreshment and brief remission of toil. Towards
the end of the day lassitude sets in, and fades into the deep unconsciousness of
healthy sleep. * * * The influences that affect the body extend not only to the
grosser modes of feeling, and to such familiar exhibitions as after-dinner oratory,
but also to the highest emotions love, anger, aesthetic feeling, and moral sensi-
bility. ' Health keeps an Atheist in the dark.' Bodilj- affliction is often the cause
of a total change in the moral nature." Bain's Mind and Body.
11. Large Brains (p. 173, ^ 53.) "As a rule the size of the brain is pro-
portional to the mental development in human beings. The rule is not strictly
maintained in every instance ; occasionally a stupid man has a larger brain than
a clever man. But these are only individual exceptions to a prevailing arrange-
ment. The following are the brain weights of several distinguished men :
Cuvier 64.5 oz.
Abercrombie .... 63 "
Daniel Webster . . 53.5 u
Lord Campbell . . . 53.5 oz.
Agassiz 53.4 "
De Morgan 52.7 u
"The average male brain in Europeans is 49.5 oz. ; the female, 44 oz. Among
idiots the weights have run from 27 to 8.5 oz. The brains of the insane are below
the average of the sane. Tall men, as a rule, have larger brains than small
men." Bain's Mind and Body.
12. The Mind Should be Intelligently Cultivated " The cultiva-
tion of the mind should be carried on with judgment, and in due submission to
the requirements of the body. If study be the duty of the youth, let him pursue
it diligently, but with such intervals of rest and bodily exertion as may maintain
good appetite and health.
"The proportion of hours of study and bodily exercise may vary with the
degree of mental work, the healthfulness of the room and surrounding air, the
natural strength of the body and the degree of health ; but as a general rule it may
be doubted whether any young person can sit at close study for more than two
hours at a time without requiring bodily exertion to sustain vital action, and rest
to recruit the mind. Two hours' mental work, and a quarter to half an hour's
bodily exercise, will be quite compatible with the greatest progress in study.
" Moreover, it may be doubted whether such a student can work with advantage
for more than eight hours a day, in addition to the intervals of rest, for the issue
will not turn on the number of hours devoted to work, but the intensity of the
attention given." Ed-ward Smith on Health.
THE SPECIAL SENSES. 177
CHAPTER X.
THE SPECIAL SEKSES.
The -Production of Sensations Variety of Sensations General Sensi-
bility Pain and its Function Special Sensation, Touch, Taste,
Smell, Sight, and Hearing The Hand, the Organ of Touch The
Sense of Touch Delicacy of Touch Sensation of Temperature and
Weight The Tongue the Organ of Taste TJie Nerves of Taste
The Se-nse of Taste and its Relations with tlie oilier Senses The
Influence of Education on the Taste The Nasal Cavities, or the
organs of SmeUTlw Olfactory Nerve The Uses of the Sense oj
Smell The Sense of Sight Light The Optic Nerve The
Eyeball and its Coverings The Function of the Iris The
Sclerotic, Choroid, and Retina The Tears and their Func-
tion The Movements of the Eyeball The Function of Ac-
commodation The Sense of Hearing and Sound The Ear, or
the organ of Heoring The External, Middle, and Internal Ear
1. Production of Sensations. We have already
seen that the true centre of sensation is some organ within
the skull, probably among the gray masses at the base of
the brain ; but the mind never perceives impressions at
that point ; but, on the contrary, always refers them to the
external organs of sensation. Hence, it is convenient to
say, that those outer pp.rts possess the property of sensibil-
ity. For instance, we say that we hear with the ear, taste
with the tongue, and feel with the fingers. That this is
not the exact truth is proven by the fact, that whenever
the nerve connecting one of these organs with the brain is
severed, it at once loses its capacity for sensation.
2. Consciousness, another faculty of the brain, is neces-
sary to complete a sensation. During sleep, and in other
unconscious states, the usual impressions are presented to
1 . True centre of sensation ? Place of the mind's impressions ? What is
convenient to say ? What further is stated ?
2. Consciousness ? During sleep ? In profound insensibility ?
178 THE SPECIAL SENSES.
the ear, the nose, and the skin, but they fail to excite sen-
sations, because the nerve-centres are inactive. In pro-
found insensibility, from chloroform or ether, a limb may
be removed without occasioning the least feeling.
3. Variety of Sensations. All animals have some
legree of sensibility. It is of course feeble and indistinct
:n the lower forms of life, but increases in power and vari-
ety as we ascend the scale. In the earth-worm, the nerv-
ous system is very simple, the sensibility being moderate
and alike in all parts : hence, if its body be cut into two
pieces, each piece will have the same degree of feeling as
before. As we approach man, however, the sensations
multiply and become more acute; the organs are more
complex, and special parts are endowed with special gifts.
These special organs cannot be separated from the rest of
the body without the loss of the functions they are de-
signed to exercise.
4. The lowest form of sensation, that of simple contact,
is possessed by the lowest of the animal creation. The
highest forms are those by which we are enabled to know
the properties of external objects, such as shape, size,
sound, and color. A variety of means of communicating
with the outer world is the necessary possession of a high
intelligence. Sensations are modified by use. They be-
some more acute and powerful oy moderate exercise ; or,
they are dulled by undue excitement. The former is
shown by the acute hearing of the Indian, by the sharp
sight of the sailor, and by the delicate touch of the blind.
The latter is exemplified by the impaired hearing of the
boiler-maker, and the depraved taste of him who uses
pungent condiments with his food. Again, impressions
habitually presented may not be consciously felt; as is
the case with the rumbling of carriages in a neighboring
3. Sensibility in animals ? In the earth-worm ? In man ?
4. The lowest form of sensation ? The highest? Sensations, how modified?
What further can you state as to habitual impressions?
THE SPECIAL SENSES. 179
street, or the regular ticking of a clock. All sensations
become less vivid with the advance of age, especially hear-
ing and vision.
5. General Sensibility .There is a property pos-
sessed by nearly all parts of the human body which we
call general sensibility. We have recently seen that the
brain is wholly insensitive, and may be cut or pinched
without pain. The same is true of the nails, hair, the
scarf-skin or external covering of the body, and a few other
structures. In these parts no nerves are found. On the
other hand, the sensibility of the true skin, and of mucous
membranes, as of the eye and nose, is exquisite, these or-
gans having a large supply of senso*/ nerve-fibres. The
bones and tendons have less of these fibres, and are only
moderately sensitive.
6. The sensibility of any part of the body, then, de-
pends upon the number of nerves present; and, as a rule,
the nervous supply is proportional to the importance of
the part, and to its liability to injury. When, therefore, a
surgical operation is performed, the most painful part of it
is the incision through the skin ; the muscles, cartilage,
and bone being comparatively without sensation. Hence,
if we could benumb the surface, certain of the lesser oper-
ations might be undergone without great inconvenience.
This is, in fact, very successfully accomplished by means of
the cold produced by throwing a spray of ether, or of some
other rapidly evaporating liquid, upon the part to be cut.
7. Tickling is a modification of general sensibility. At
first, it excites a pleasurable sensation, but this soon passes
into pain. It is only present in those parts where the
sense of touch is feeble. But all impressions are not
received from without: there are, also, certain internal
5. General sensibility? What have we seen as regards the brain? Of what
other structures is the same true?
6. The cause of sensibility ? Painful part in a surgical operation ? Benumb-
ing the surface ? How done by ether ?
7 Tickling? Internal sensations? The nerves of general sensibility ?
180 THE SPECIAL SENSES.
sensations, as they are called, which depend upon the con-
dition of the internal organs, such as appetite, hunger,
thirst, the sense of satisfaction after taking food, dizziness
when looking down from some lofty position, lassitude,
drowsiness, fatigue, and other feelings of comfort or dis-
comfort. General sensibility, whether of the internal or
external organs of the body, chiefly depends upon the
sensory fibres of the spinal nerve. The face, however, is
supplied by the sensory cranial nerves. The sympathetic
system has a low grade of feeling in health ; but disease in
the parts served by it arouses an intense degree of pain.
8. The Sensation of Pain. What then is pain ? Is
it identical with ordinary sensibility ? There seems to be
some necessary connection between the two feelings, for
they take place through the same channels, and they are
alike intense in the same situations. But sensibility
habitually contributes to our sources of pleasure, the very
opposite of pain ; hence, these feelings cannot be identical.
9. Pain must, therefore, be a modification of the general
sensibility, which follows an excessive degree of excitement
of the nerves ; there being a natural limit to the amount of
stimulation which they will sustain. So long as this limit
is observed, the part excited may be said to be simply sen-
sitive; but when it is exceeded, the impression becomes
painful. This difference between sensibility and pain is
well shown by the effects of sunlight upon the eye. The
indirect illumination of the sun arouses only the former
feeling, and is indispensable to our comfort and existence ;
while the direct ray received into the eye occasions great
pain.
10. The Uses of Pain. The dread of pain is a valu-
able monitor to the body. It puts us on our guard in the
presence of danger; teaches moderation in the use of our
8. Connection between pain and sensibility?
9. Explain the difference between pain and sensibility.
1O- Dread of pain ? How may its value be appreciated ? Example
THE SPECIAL SENSES. 181
powers; indicates the approach of disease; and calls at-
tention to it when present. The word disease, in fact,
according to its original use, had reference simply to the
pain, or want of ease, which commonly attends disordered
health. When we observe the serious mishaps which occur
when sensibility and pain are absent, we cannot fail to
appreciate its value. For example, a paralytic in taking a
foot-bath, forgets to test its temperature, and putting his
limbs into water while it is too hot, is severely scalded
without knowing it.
11. A traveller, overcome by cold and fatigue, lies down
and falls asleep near a large fire, and when he is aroused in
the morning, it is discovered that one of his feet has been
insensibly destroyed. A grain of sand, lodging in an insen-
sitive eye, may cause inflammation and even the loss of
sight. If intense light were not painful to the eye, many
a child would innocently gaze upon the glories of the sun
to the ruin of his sight.
12. Pain is, indeed, a present evil, but its relations with
the future prove its mission merciful. Painful impressions
'cannot be recollected from past experience ; and they can-
not be called into existence by the fancy. Considered in
the light of results, pain has a use above that of pleasure ;
for while the immoderate pursuit of the latter leads to
harm, the tendency of pain is to restrict the hurtful courses
of life, and in this manner to protect the body.
13. The relations of pain to pleasure are thus described
by the eminent physiologist, Magendie: "By these sensa-
tions Nature induces us to concur in 'the order which she
has established among organized beings. Though it may
appear like sophistry to say that pain is the shadow of
pleasure, yet it is certain that those who have exhausted
the ordinary sources of pleasure have recourse to th
1 1 . The case of the traveller ? Grain of sand ? The snn and child ?
12. Mission of pain ? Painful impressions compared with those of pleasure 7
1 3. What doea Magendie eay of the relation of pain to pleasure?
182 THE SPECIAL
'
causes of pain, and gratify themselves by their effects. Do
we not see in all large cities, that men who are debauched
and depraved find agreeable sensations, where others ex-
perience only intolerable pain ?" (Read Note i.)
14. As to painful sensation among the inferior animals,
the plan of Nature seems to be, that the higher the intel-
ligence of the creature, and the more complete its power
of defence, the more acute is its sensibility. We infer,
therefore, that animals low in the scale of existence, and
helpless, are not very liable to suffer pain.
15. Special Sensation. The sensations of simple
contact and pain are felt by nearly all parts of the system,
whether external or internal, and are the necessary con-
sequence of the general sensibility ; but, so far as the ob-
jects which surround us are concerned, these impressions
are vague and passive in character, and inform the mind
of none of the properties or powers of these objects. Be-
sides these feelings, therefore, man is endowed with certain
special sensations, which are positive and distinct in char-
acter,, and which he can call into exercise at will, and em-
ploy in the pursuit of knowledge. For reasons relating to
the original constitution of the body, these sensations are
to be regarded as modifications of the general sensibility
already alluded to, constructed with special reference to
the different forces of Nature, of which we have any
^knowledge, such as heat, motion, gravity, sunlight, and
the like. (Read Note 6, end of Chapter.)
16. These distinct and active faculties are termed the
special senses, and are five in number, viz., Touch, Taste,
Smell, Sight, and Hearing. For the exercise of these
senses, special organs are furnished, such as the hand, the
tongue, the nose, the eye, and the ear. The manner in
which the nerves of special sense terminate, varies in the
14. The law of Nature as regards painful sensations amon? animals ?
15. The sensation of conuict and pain? Special sensations of man? How
teparded ?
6. What are the special senses ? Special organs for them ?
THE SPECIAL SENSES. 183
case of each organ, so that each is adapted to one set of
sensations alone, and is incapable of perceiving any other.
Thus the nerve of hearing is excited by the undulations of
sound, and not by those of light, while the reverse is true
of the nerve of sight; and the nerve of smell can appreciate
neither of them, being capable only of taking cognizance
f the odorous properties of bodies. (Note 7, end of Chapter.}
17. By some writers six senses are accorded to man ; the
additional one being either the sense of temperature, for as
we shall presently see this is not the same as touch ; or
according to others, the muscular sense by which we are
enabled to estimate the weights of bodies. The latter also
differs in some respects from the sense of touch.
fl 18. Organs of Touch. The sense of touch is pos-
sessed by nearly all portions of the general surface of the
body, but it finds its highest development in the hands.
The human hand is properly regarded as the model organ
of touch. The minute structure of the skin fits it admi-
rably for this form of sensation : the cuticle, or scarf-skin,
is fine and flexible, while the cutis, or true skin, contains
multitudes of nerve-filaments, arranged in rows of papilla-.
or cone-like projections, about one-hundredth of an inch in
length. It is estimated that there are 20,000 of these papillae
in a square inch of the palmar surface of the hand. Now,
although the nerves of the cutis are the instruments by
which impressions are received and transmitted to the
brain, yet the cuticle is essential to the sensation of touch.
This is shown by the fact that whenever the true skin is
laid bare, as by a burn or blister, the only feeling that it
experiences from contact is one of pain, not that of
touch.
19. The office of the cuticle is thus made evident: it is
to shield the nerve filaments from direct contact with ex-
1 7. What, is paid in relation to one more than the five senses ?
18. The sense of touch, how prevalent ? What is said of the hand ?
19. Office of the cuticle ? Tips oi the fingers ? The fingers with thumb ?
184 THE SPECIAL SENSES.
fcernal objects. At the tips of the fingers, where touch is
most delicate, the skin rests upon a cushion of elastic
material, and receives firmness and permanence of shape
by means of the nail placed upon the less sensitive side.
Besides these favorable conditions, the form of the arm is
such, and its motions are so easy and varied, that we are
able to apply the test of touch in a great number of direc-
tions. The slender, tapering fingers, with their pliant
joints, together with the strong opposable thumb, enable
the hand to mold itself upon and grasp a great variety of
objects; so that great as are the delicacy and grace of the
hand, it is not wanting in the elements of power.
20. Its beauty and adaptation to the wants of man have
made the hand an attractive theme for philosophers.
They do not, however, always agree in their conclusions.
One has the opinion that man has acquired his intelligence
and achieved his place as " lord of creation," because he
has this organ. Buflfon, in effect, declares that with fingers
twice as numerous and twice as long, we would become
proportionally wiser; but Galen long ago took a more
reasonable view, when he taught that "man is the wisest
of animals, not because he possesses the hand ; but because
he is the wisest and understands its use, the hand has been
given to him; for his mind, not his hand has taught him
the arts." Another has well said, that " no one can study
carefully the human hand and fail to be convinced of the
existence of the Deity."
21. The Sense of Touch. Touch is the simplest of
the senses. It is that which the child first calls into ex-
ercise in solving the early problems of existence; and it is
that which is in the most constant use throughout life.
We are brought by the touch into the most intimate rela-
tions with external objects, and by it we learn th* greater
number, if not the most important, of the properties of
tO. What special importance is attributed to the hand?
1 . The simplicity of touch ? What docs it tyach us ?
THE SPECIAL SENSES. 185
these objects; such as size, figure, solidity, motion, and
smoothness or roughness of surface.
22. The sense of touch assists the other senses, especially
that of sight, giving foundation and reality to their per-
ceptions. Without it, the impressions received by the eye
would be as vague and unreal as the figures that float
through our dreams. A boy who had been blind from
birth, at the age of twelve years received sight by means
of a surgical operation : at first, he was unable to distinguish
between a globe and a circular card, of the same color, be-
fore he had touched them. After that, he at once recog-
nized the difference in their form. He knew the peculiari-
ties of a dog and a cat by feeling, but not by sight, until
one day, happening to take up the cat, he recognized the
connection of the two sorts of impressions, those of touch
and sight; and then, putting the cat, down, he said: "So,
puss, I shall know you next time."
23. Touch is considered the least liable to error of all
the senses ; yet, if that part of the skin by which the sense
is exercised is removed from its customary position, a false
FIG. 45.
impression may be created in the mind. This is well il-
lustrated by an experiment, which dates from the time of
Aristotle. If we cross the middle finger behind the fore-
22. Importance of the sense of touch to the development of the other senses ?
23. Liability of touch to err? Describe the illustration.
186 THE SPECIAL SENSES.
finger, and then roll a marble, or some small object, upon
the tips of the fingers (see Fig. 45), the impression will be
that two marbles are felt. If the fingers, thus transposed,
be applied to the end of the tongue, two tongues will be
felt. When the nose is accidentally destroyed, the surgeon
sometimes performs an operation for the purpose of form-
ing a new one, by transplanting a partially removed piece
of the skin of the forehead upon the injured part : then, if
the new nose be touched or pinched, the feeling is referred
to the forehead. This fact illustrates one important truth,
that the nerves will re-unite after they have been cut, and
feeling will be restored : if it were otherwise, a succession
of slight cuts upon the fingers would seriously impair their
tactile sensibility.
24. The Delicacy of Touch. Although the hand
is the proper organ . of this sense, yet it is exercised by
various parts of the body, their degree of sensibility being
proportional to the number of papillae they contain. The
varying degrees of tactile delicacy of the diiferent part? of
the surface have been measured, in an ingenious manner,
by means of a pair of compasses, tipped with small pieces
of cork. The two points of the compasses are touched at
the same moment to the skin, the eyes being closed, and it
is found that, in sensitive parts, the distance between the
points may be quite slight, and yet each be plainly felt ;
while, in less sensitive parts, the points of the compasses
are felt as a single point, although they are separated one
or two inches.
25. At the tips of the fingers, the distance between the
points being one-twentieth of an inch, a double impression
is felt. The distance must be twice as great, for the palm;
four times as great, for the lips ; and, on the forehead, it
must be twenty times greater. At the middle of the back,
where the touch is least acute, the points must be sepa-
24. The delicacy of touch 1 Experiments with a pair of compasses 7
25. Further experiments and results ?
THE SPECIAL SEKSES. 187
rated more than two inches before they can be .separately
felt. Therefore, the sense of touch in the fingers is said to
be fifty times more delicate than upon the posterior sur-
face of the body.
26. Exquisite delicacy of touch is attained by practice.
This is shown in many of the lighter and more graceful
employments of daily life. Without it, the skill of the
painter, sculptor, and musician would be rude indeed. By
training, also, the physician acquires the tactus eruditus,
or discriminating touch ; but among the blind, delicacy of
touch is most remarkable, and it here finds its highest
value; for its possession, in a measure, compensates the
loss of sight by enabling them to read, by means of* raised
letters, to work with certain tools, and even to play upon
musical instruments. A person born without sight, and
without hearing or voice, may, by the education of the
touch, be rescued from apparent imbecility, and be taught
not only to read and write, but even to perform household
and other useful labors.
27. Sensations of Temperature and Weight.
Each of these sensations has been described by the physi-
ologists as a special sense, and they are rival candidates, so
to speak, for the position and title of the sixth sense. In the
sensation of temperature, or the thermal sense, touch bears
a part, but the two feelings appear to be distinct. In proof
of this, we observe, firstly, that they are not alike intense
in the same situations; as, fo r example, the skin of the face
and elbow, where the sense of touch is feeble, is very sensi-
tive to impressions of heat and cold. Secondly, the ability
to recognize temperature may be lost by paralysis, while
the ^ sensibility of touch remains unaffected. When the
skin comes in contact with a very hot substance, the sen-
sation felt is that of pain, not of touch. In like manner, a
26. Exquisite delicacy of touch ? The same among the blind ?
27. Rival candidates for the sixth sense? Give the two reasons on the sub-
ject.
r
188 THE SPECIAL SENSES.
very cold substance causes pain, not the feeling of cold.
So that a red-hot iron, and solid carbonic acid (the tem-
perature of which is 108 below zero), feel alike ; and each,
if pressed slightly, will produce a blister. (Read Note 8.)
28. The muscular sense, by some considered distinct
from touch, gives rise to the sensations of weight, and
other forms of external resistance. That this feeling
exists, is shown by the following simple experiment. If
the hand be placed flat upon a table, and a somewhat
heavy weight be put into it, touch alone is exercised
and a feeling of pressure results; but if the hand be
raised, a certain amount of muscular effort must be put
forth, and thus the sensation of weight is recognized.
Through the muscular sense, precision of effort is rendered
possible ; for by it we learn to adjust the force exerted to
the weight of the object to be lifted, moved, or carried.
Without it, all our movements would necessarily become
ill-regulated and spasmodic. In cases of disease, where the
sensibility of the lower limbs is lost, while power of motion
remains, the patient is able to stand erect so long as he
can see his limbs; but just as soon as his eyes are closed,
he begins to waver, and will fall unless supported.
29. The Organ of Taste. The tongue is the special
organ of the sense of taste ; but the back part of the mouth
also possesses this faculty. The tongue is a muscular
organ, the muscles composing it being so numerous and
interwoven as to give it the freedom and variety of motion
which it possesses. It can curve itself upward or down-
ward; it can extend or contract itself; and, with its point,
can sweep the cavity of the mouth, in all directions, in
the search for scattered particles of food.
30. The upper surface of the tongue is peculiar, being
marked by the presence of innumerable papillce, some of
28. The muscular sense ? State what IP said to illustrate the subject.
29. The oriran of taste ? The lonjnie ? Its powers of motion?
30. Peculiarities of the tongue ? Uses of the papillae ?
THE SPECIAL SENSES. 189
which are of microscopic size, resembling those thai
abound in the fingers, and in other parts of the body
that have the sense of touch. Others are much larger,
and give to the tongue its roughness of feeling and ap-
pearance. Through the medium of these papillae, the
tongue receives impressions of touch and temperature, as
well as taste : indeed, its extremity is fully as delicate, in
respect to tactile sensations, as the tips of the fingers them-
selves. It can recognize the two points of the compasses
when separated not more than one-twenty-fourth of an
inch ; the back of it is much less sensitive to touch, while
at the same time it is more highly sensitive to impressions
of taste.
31. Each lateral half of the tongue resembles the other
in structure, and each receives the same number of nerves
three. One of these regulates motion, the other two are
nerves of special sense. One of the latter supplies the
front half of the tongue, and is called the gustatory nerve.
This is a branch of the great cranial nerve, called the
"fifth pair," which ramifies in all parts of the face. The
back of the tongue is endowed with the power of taste
through a nerve known as the glosso-pliaryngeal, because
it is distributed both to the tongue and throat. This dif-
ference in the nervous supply of the tongue becomes signif-
icant, when we learn, as we shall presently, that each part
of it perceives a different class of flavors.
32. The Sense of Taste. Taste is the special sense
by means of which we discover the savors, or flavoring
properties of the substances, which come in contact with
the tongue. Mere contact with the surface of the tongue,
however, is not sufficient, but contact with the extremities
of the nerves of taste within the papillae is required. In
order that the substance to be tasted may penetrate the
31. Resemblance tn the parts of the tongue? Powers and functions of thf
pa/tp ?
J2. Taste ? What are the requisites? to taste ?
190 THE SPECIAL SENSES.
cells covering the nerves, it must either be liquid in form,
or readily soluble in the watery secretion of the mouth,
the saliva. The tongue must be moist also. If the sub-
stance be insoluble, as glass or sand, or the tongue dry, the
sense of taste is not awakened. In sickness, when the
tongue is heavily coated, the taste is very defective, or, as
is frequently expressed, " nothing tastes aright."
33. All portions of the tongue are not alike endowed
with the sense of taste, that function being limited to the
posterior third, and to the margin and tip of this organ.
The soft palate, also, possesses the sense of taste ; hence,
an article that has an agreeable flavor may very properly
be spoken of as palatable, as is often done. All parts of
the tongue do not perceive equally well the same flavors.
Thus, the front extremity and margin, which is the por-
jion supplied by the "fifth pair" of nerves, perceives more
acutely sweet and sour tastes; but the base of the tongue,
supplied by the glosso-pliaryngeal nerve, is especially sen-
sitive to salt and bitter substances. The nerve of the front
part of the tongue, as before stated, is in active sympathy
with those of the face, while the relations of the other
nerve are chiefly with the throat and stomach ; so that
when an intensely sour taste is perceived, the countenance
is involuntarily distorted, and is said to wear an acid ex-
pression. On the other hand, a very bitter taste affects
certain internal organs, and occasions & sensation of nau-
sea, or sickness of the stomach. (Read Note 2.)
34. Relations of Taste with other Senses.
Taste is not a simple sense. Certain other sensations, as
those of touch, temperature, smell, and pain, are blended
and confused with it; and certain so-called tastes are really
sensations of another kind. Thus an astringent taste, like
that of alum, is more properly an astringent feeling, and
33. Portions of the tongue endowed with taste? Where else does the sense
!odr ? What is stated in respect to sweet and hitter flavors ? Reflex effects men-
tioned ?
34 1 What is stated of the relations of tasty with other sense.s ?
THE SPECIAL SENSES. 191
results from an impression made upon the nerves of touch,
that ramify in the tongue. In like manner, the qualities
known as smooth, oily, watery, and mealy tastes, are depend-
ent upon these same nerves of touch. A burning or pungent
taste is a sensation of pain, having its seat in the tongue and
throat. A cooling taste, like that of mint, pertains to that
modification of touch called the sense of temperature.
35. Taste is largely dependent upon the sense of smell.
A considerable number of substances, like vanilla, coffee,
and garlic, which appear to possess a strong and distinct
flavor, have in reality a powerful odor, but only a feeble
taste. When the sense of smell is interfered with by hold-
ing the nose, it becomes difficult to distinguish between sub-
stances of this class. The same effect is frequently observed
when smell is blunted during an ordinary cold in the head.
Sight also contributes to taste. With the eyes closed, food
appears comparatively insipid; and a person smoking
tobacco in the dark is unable to determine by the taste
whether his cigar is lighted or not. Accordingly, it is not
a bad plan to close the nose and shut the eyes when about
to swallow some disagreeable medicine.
36. Influence of Education on the Taste. The
chief use of the sense of taste appears to be to act as a
guide in the selection of proper food. Hence its organs are
properly placed at the entrance of the digestive canal. As
a general rule, those articles which gratify the taste are
wholesome ; while the opposite is true of those which im-
press it disagreeably. This statement is more exact in
reference to the early years of life than to later years,
when, by reason of mischievous habits, the sense of taste
has become dulled or perverted. The desires of a child
are simple ; he is fully satisfied with plain and wholesome
articles of diet, and must usually "learn to like" those
35. Its dependence on smell? on sight ?
36. The chief use of the sense of taste? The position of its organs ? The rule
as regards wholesome and unwholesome food ? Remarks respecting the rule?
1.92 THE SPECIAL SENSES.
which, have a strongly marked flavor. Accordingly, it is
far easier at this age to encourage the preference for plain
food, and thus establish healthful habits, than later in life
to uproot habits of indulgence in stimulating substances,
after their ill effects begin to manifest themselves.
37. The tastes of men present the most singular diversi-
ties, partly the result of necessity and partly of habit or
education. The Esquimaux like the rank smell of whale
oil, which is a kind of food admirably suited to the require-
ments of their icy climate ; and travellers who go from oui
climate to theirs are not slow to develop a liking for the
same articles that the natives themselves enjoy. The sense
of taste is rendered very acute by education, as is shown in
an especial manner by those who become professional
" tasters" of tea and wine.
38. The Sense of Smell the Nasal Cavities.
The sense of smell is located in the delicate mucous
membrane which lines the interior of the nose. That
prominent feature of the face, the nose, which is merely
the front boundary of the true nasal organ, is composed
partly of bone and partly of cartilage. The upper part of
it is united with the skull by means of a few small bones ;
to which circumstance is due its permanence of shape.
The lower portion, or tip of the nose, contains several thin
pieces of cartilage, which render it flexible and better able
to resist the effects of blows and pressure. Behind the
nose we find quite a spacious chamber, separated from
the mouth by the hard palate, forming the "roof of the
mouth," and by the soft palate (see Fig. 46) ; and divided
into two cavities by a central partition running from be-
fore backward.
39. These nasal cavities, constituting the true beginning
of the air-passages, extend from the nose backward to the-
37. Diversity in tastes of men ? How shown ? The education of the sense ol
taste?
38. Location of the sense of smell? The nose? " Roof of the mouth?"
39 1 Cavities of the nose '( Obstruction of the passage of air through them ?
THE SPECIAL SENSES.
193
upper opening of the throat, and rise as high as the junc-
tion of the nose with the forehead. The inner wall of
each cavity is straight and smooth ; but from the outer
wall there jut into each cavity three small scroll-like
bones. The structure of these bones is very light, and
hence they have been called the " spongy" bones of the nose.
In this manner, while the extent of surface is greatly in-
creased by the formation of these winding passages, the
cavities are rendered extremely narrow ; so much so, in fact,
that a moderate swelling of the mucous membrane which
lines them, as from a cold, is sufficient to obstruct the pass-
age of air through them.
40. The Nerve of Smell. The internal surface of
the nasal passages is covered by a delicate and sensitive
mucous membrane. Its surface is quite extensive, follow-
ing as it does, all the inequalities produced by the curved
spongy bones of the nose. The upper portion of it alone
is the seat of smell, since that part alone receives branches
from the "first pair"
of cranial nerves, or
the olfactory nerve,
which is the special
nerve of smell (see
Fig. 43). v In Fig. 46
is shown the distri-
bution of this nerve,
in the form of an
intricate network
upon the two upper
spongy bones. The
nerve itself (1) does not issue from the skull, but rests
upon a thin bone which separates it from the cavity of the
nose; and the branches which proceed from it pass through
this bone by means of numerous small openings. The en-
FIG. 46. SECTION OF THE RIGHT NASAL CAVITY.
40. The special nerve of smell ? Its location ?
r
194: THE SPECIAL SENSES.
graving represents the outer surface of the right nasal
cavity; the three wave-like inequalities, upon which the
nervous network is spread out, are due to the spongy bones.
^The left cavity is supplied in the same manner.
41. The nerves which ramify over the lower part of the
membrane, and which endow it with sensibility to touch
and pain, are branches of the " fifth pair" of nerves. An
irritation applied to the parts where this nerve is distrib-
uted occasions sneezing, that is, a spasmodic contraction
of the diaphragm ; the object of which is the expulsion of
the irritating cause. The manner in which the olfactory
nerve-fibres terminate is peculiar. Unlike the extremities
of other nerves, which are covered in by a greater or less
thickness of tissue, these come directly to the surface of
the mucous membrane, and thus come into very close con-
tact with the odorous particles that are carried along by the
respired air. The surface is at all times kept in a moist
condition by an abundant flow of nasal mucus ; otherwise
it would become dry, hard, and insensitive from the con-
tinual passage of air to and fro in breathing. Birds,
which respire more actively than men, have a special
gland, for secreting a lubricating fluid, located in the air-
passages of the head.
42. The Uses of the Sense of Smell, Smell is
the special sense which enables us to appreciate odors.
Touch, as we have seen, is largely concerned with solid
bodies; and taste, with fluids, or with solids in solution.
Smell, on the other hand, is designed to afford us informa-
tion in reference to substances in a volatile or gaseous
form. Invisible and subtile particles emanate from odor-
ous bodies, and are brought by the respired air in contact
with the terminal filaments of the olfactory nerve, upon
which an agreeable or disagreeable impression is. produced.
4 1 . Branches of the " fifth pair 11 of nerves ? Nasal mucus ? Birds ?
42. Smell? Touch? Taste? Design of smell ? Invisible and #a>eous parti
cles ? The extreme fineness of the particles 1 Musk ? Ju gther cases ?
THE SPECIAL SENSES. 195
The fineness of the particles that constitute odors is often so
extreme, that they elude all attempts to measure or weigh
them. A piece of musk, for instance, may be kept for sev-
eral years, constantly emitting perfume, without any ap-
preciable loss of weight. In other cases, a loss of substance
is perceptible, such as the essential oils, which enter into
the composition of the ordinary perfumes.
43. Smell, like taste, aids us in the choice of proper
food, leading us to reject such articles as have a rank or
putrid odor, and which are, as a rule, unfit to be eaten.
The highest usefulness of this sense, however, consists in
the protection it affords to the organs of respiration. Sta-
tioned at the gateways of the air-passages, it examines the
current of air as it enters, and warns us of the presence of
noxious gases, and of other and generally invisible ene-
mies to health. Not all dangerous vapors are offensive,
but almost all offensive vapors are unfit to be breathed. A
number of small stiff hairs grow from the margin of
the nostrils to prevent the entrance of dust and other at-
mospheric impurities, which would be alike injurious to the
olfactory mucous membrane and to the lungs. The benev-
olent design of the Maker of our bodies may be observed in
all parts of their mechanism ; but, probably, in none is it
more clearly displayed than in connection with the sense
of Smell. (Read Note ^
44. The sense of smell is developed in a remarkable de-
gree in certain of the inferior animals, and is especially
acute in reference to the peculiar emanations that appear
to characterize the different animals. The lion and other
carnivorous beasts scent their prey from a great distance;
and the fox-hound is able to track the fox through thickets
and over open country for many miles ; while the timid,
helpless herbivora, such as the deer and sheep, find in the
43. Aid given by nmell? The highest nse of the sense? Explain the manner.
44. Sense of smell in the inferior animals? How, and iu what cases,
toted*
196 THE SPECIAL SENSES.
sense of smell a means of protection against their natural
enemies, of whose approach they are in this manner warned.
By training this sense in the dog, and making it subservi-
ent to his use, man is able to hunt with success certain shy
and very fleet animals, which otherwise he could but sel-
dom approach. Among men, individuals differ greatly in
respect to the development of this sense; and especially
in certain savage tribes it is found to be extremely deli-
cate. Humboldt states that the natives of Peru can, by
this sense, distinguish in the dark between persons of dif-
( ferent races. (Read Note 4.)
p 45. The Sense of Sight. Sight, or Vision, is the
/ special sense by means of which we appreciate the color,
form, size, distance, and other physical properties of the
objects of external nature. Primarily, this sense furnishes
us with information concerning the different shades of
color and the different degrees of brightness: these are
the simple sensations of sight, such as the yellowness and
glitter of a gold coin. In addition to these, there are com-
posite visual sensations, produced by the joint action of
the other senses and by the use of the memory and judg-
ment; such as, in the case of the coin, its roundness,
solidity, size, its distance and direction from us. So that
many jof our sensations, commonly considered as due to
sight, are in reality the results of intellectual processes
which take place instantaneously and unconsciously.
46. This faculty not only has value in the practical
every-day affairs of life, but it contributes so largely to the
culture of the intellect and to our higher forms of pleasure,
that some writers are disposed to rate it as the first and
most valuable of the senses. Others, however, maintain
that the sense of hearing does not yield in importance to
that of sight; and they cite in support of their position
45. What is sight ? What information docs it furnish ? Composite visual sen-
46. Comparison between sight and hearing? Relative capacity of deaf and
THE SPECIAL SENSES. 197
the fact that the blind are commonly cheerful and gay,
while the deaf are inclined to be morose and melancholy.
In respect to the relative capacity for receiving education
in the deaf and blind, it is found that the former learn
more quickly, but their attainments are not profound;
while the blind acquire more slowly, but are able to study
more thoroughly.
47. Light. The Optic Nerve. Unlike the senses
previously considered touch, taste, and smell sight does
not bring us into immediate contact with the bodies that
are examined; but, by it, we perceive the existence and
qualities of objects that are at a greater or less distance
from us. In the case of the stars, the distance is incalcu-
lable, while the book we read is removed but a few inches
Light is the agent which gives to this sense its wide range.
The nature of this mysterious force is not known, and it is
not here to be discussed; since its study belongs more
properly to the province of natural philosophy.
48. It is sufficient, in this connection, to state that the
theory of light now generally accepted, and which best
explains the facts of optics, is that known as the undula-
tory theory. This theory supposes that there exists an
intangible, elastic medium, which fills all space, and pene-
trates all transparent substances, and which is thrown into
exceedingly rapid undulations or waves, by the sun and
every other luminous body ; the undulations being propa-
gated with extreme rapidity, and moving not less than
186,000 miles in a second.
49. These waves are thought to produce in the eye the
sensation of light, in the same manner as the sonorous
vibrations of the air produce in the ear the sensation of
sound. That part of the eye which is sensitive to these
waves is the expansion of the optic nerve. It is sensitive
47. Sight, unlike the oth^r pauses? In the case of the stars ?
48. The umlulatory theory ol'li<?ht ? What does the theory suppose!'
49. The sensation of li^ht ? Opti
198 THE SPECIAL SENSES.
to no other impression than that of light, and it is the only
nerve which is acted upon by this agent. The optic nerve,
also called the " second pair" of cranial nerves, is the means
of communication between the eye and the brain.
50. The two nerves constituting the pair, arise from
ganglia lying at the base of the cerebrum, one of them on
each side; from which points they advance to the eyes,
being united together in the middle of their course in the
form of the letter X (Fig. 432). By this union the two
eyes are enabled to act harmoniously, and in some respects
to serve as a double organ. And by reason of this same in-
timate nervous communication, when serious disease affects
one eye, the fellow-eye is extremely liable to become the
seat of sympathetic inflammation; and this, if neglected,
almost certainly results in hopeless blindness.
51. The Organ of Sight. The Eye. The proximity
of the eye to the brain, and the important part it per-
forms in giving expression to the emotions, have given it
the name of "the window of the soul." The exceeding
beauty of its external parts, and the high value of its func-
tion, have long made this organ the subject of enthusiastic
study. It is chiefly within the last twenty years, however,
that this study has been successful and fruitful of practical
results. Several ingenious instruments have been invented
for the examination of the eye in health and disease, and
new operations have been devised for the relief of blindness
and of impaired vision. As a result, it is now a well-
marked fact that, in civilized lands, the number of those
who suffer from loss of sight is proportionally much less
than in countries where scien3e is less known and culti-
vated.
52. The most obvious fact in respect to the apparatus of
5O The two nerves constituting the pair of nerves ?
51. Why is the eye called the " window of the soul?" Why, the subject of
enthusiastic study?
52. The most obvious fact? The consequence? The nest thing noticed?
Its range of view ? Of what does the organ of vit- ion consist ?
THE SPECIAL SENSES. 199
sight is that there are two eyes, which may either act to-
gether as one, and be fixed upon one object, or one eye may
be used independently of the other. In consequence of
this arrangement the loss of one eye does not necessitate
blindness, and, in fact, it not infrequently happens that the
sight of one eye may be long impaired or lost before the
fact is discovered. We next notice that it is placed at the
most elevated part of the body, in front, and near the brain.
It also commands a wide range of view, being itself moved
with great rapidity, and being further aided by the free
motion of the head and neck. The organ of vision consists
essentially of two parts : the optical instrument itself the
eyeball and its enveloping parts, or the case in which the
instrument is kept free from harm. The latter, which are
external, and which we shall first consider, are chiefly the
Orbits, the Eyelids, and the apparatus for the Tears.
53. The Orbits. The eyeball, which is a delicate
organ, is well defended against external injury within the
orbits or bony sockets of the head. These are deep conical
hollows, bounded in part by the bones of the skull, and in
part by those of the nose and cheek. The orbit juts out
beyond the most exposed portion of the eyeball, as may be
seen by laying a book over the eye, when it will be found
thai; no part of the eyeball, unless it be very prominent,
will be touched by the book ; so that the only direction in
which an injury is liable to be received is immediately in
front of the eye. The overhanging brow is itself covered
by a layer of thick skin, studded with short, stout hairs,
which are so bent as to prevent the perspiration from run-
ning into the eye and obscuring vision. Through a hole
in the bottom of the orbit, the nerve of sight passes out-
ward from the brain. The orbit also contains a considera-
ale amount of a fatty tissue, upon which, as upon an elastic
cushion, the eye rests.
o3. The protection of the eyeball against injury? The overhanging brow?
The opening for the optic nerve f
200
THE SPECIAL SENSES.
FIG. 47. FRONT VIEW
(Natural Size.)
1. The Lachrymal, or tear gland, lying be-
neath the upper eyelid.
2. The Nasal r>uct is shown by the dotted
/ine. The * marks the orifice iu the lower
lid.
54. The Eyelids. The eyelids are two movable cur-
tains, or folds, which, when shut, cover the front part of
the orbit, and hide the
eye from view. The up-
per lid is the larger, has a
curved margin, and moves
freel} 7 , while the lower lid
is comparatively short
and straight, and has but
a slight degree of motion
(Fig. 47). Skin covers
the exterior of the lids,
while a fine mucous
membrane lines their in-
ner surface, and is like-
The central black spot is the pupil; sur- -WICA crvrpo/l nnf nvpr flip
rounding it is the iris; and the triangular W1S6 s P reatl out ^ er tne
SiS^ paces are the visible portion Ol the entire front of the eye-
ball. This membrane,
which is called the Conjunctiva, is highly sensitive, and
thus plays an important part in protecting the eye against
the lodgment of sand, ashes, chaff, and other foreign parti-
cles that are blown about in the air. This sensitive mem-
brane will not endure the presence of these particles. If
any find access, it causes a constant winking, a flow of
tears, and other signs of irritation, until it is removed.
55. The long, silky eyelashes, which garnish the edges
of the lids, act like a sieve to prevent the entry of dust and
the like; and together with the lids, they regulate the
amount of light which is permitted to enter the eye, so that
it is shielded from a sudden flood or glare of light. The little
points seen in the figure just within the line of the lashes,
especially on the lower lid, represent the mouths of numer-
ous little sebaceous glands (Fig. 48, D,D), such as are always
54, What are the eyelids? The upper lid? The lower one? The mucous
membrane of the eye ?
55. The eyelashes ? The little points within the line of the lashes ? Of wha:
use are these glands ?
THE SPECIAL SENSES. 201
found in the neighborhood of hairs. These glands supply
a thick, oily material which greases the edges of the lids
and prevents their adhering together, and likewise prevents
the overflow of the tears upon the cheek.
56. The Lachrymal Fluid, or the Tears. Just
within the outer part of the bony arch cf the brow, where
the bone may be felt to be sharper than in other positions,
is lodged a little organ called the lachrymal gland, the sit-
uation of which is indicated in Fig. 4t, 1. This is the
gland whence flows the watery secretion, commonly called
the tears, which is designed to perform an exceedingly im-
portant duty in lubricating the lids, and in keeping the
exposed surface of the eyeball moist and transparent. For,
without this or some similar liquid, the front of the eye
would speedily become dry and lustreless, like that of a
Ssh which has been removed from the water : the simple
exposure of the eye to the air would then suffice to destroy
vision.
57. This secretion of the tears takes place at all times,
during the night as well as the day; but it is seldom
noticed, except when under the influence of some strong
mental emotion, whether of sorrow or happiness, it is
poured forth in excess, so as to overflow the lids. Strong
light or a rapid breeze will, among many other causes, ex-
cite the flow of the tears. That portion of this secretion
which is not used in moistening the eye is carried off
into the nose by a canal situated near the inner angle of
the eye, called the nasal duct. This duct is shown in Fig.
47, 2, and is connected with each lid by delicate tubes,
which are indicated by dotted lines in the figure ; the as-
terisk marks the little opening in the lower lid, by which
the tears enter the nasal duct. By gently turning the
inner part of that lid downward, and looking in a mirror,
5 6. The location of the lachrymal gland ? The use of the gland ?
57. When does the secretion of the tears occur? The secretion not used for
the eye? Location o*' the nasal duct? It* uso? The overflow of tears in old
people 2
202
THE SPECIAL SENSES.
this small "lachrymal point" may be seen in your own
eye. In old people, these points become everted, and do
not conduct the tears to the nasal cavity, so that they are
inconvenienced by an overflow of tears upon the face.
58. Thus we observe that the gland which forms the
tears is placed g.t the outer part of the eye, while their
means of exit is at the inner angle of the eye ; which fact
renders it necessary that this watery fluid shall pass over
the surface of the eyeball before it can escape. This ar-
FIG. 48. VERTICAL SECTION OF THE EYE. (Enlarged.)
C, The Cornea.
A, The Aqueous Humor.
I, The Iris.
P, The Pupil.
L, The Crystalline Lens.
H, The Ligament of the Lens.
B, The Ciliary Process.
V, The Cavity containing the Vit-
reous Humor.
S, The Sclerotic.
Ch, The Choroid.
R, The Retina.
N. The Optic Nerve-
DD, The Eyelids.
X, The Levator Muscle of the Upper
Lid.
Y, The Upper Straight Muscle of the
Eye.
Z, The Lower Straight Muscle.
rangement cannot be accidental, but evinces design, for it
thus secures the perfect lubrication of the surface of the
eve, and cleanses it from the smaller particles of dust
58. The watery fluid passing over the eyeball ? Design of the arrangement >
Winking ?
THE SPECIAL SENSES. 203
which may enter it, in spite of the vigilance of the lids
and lashes. The act of winking, which is generally un-
consciously performed, and which takes place six or more
times in a minute, assists this passage of the tears across
the eye, and is especially frequent when the secretion is
most abundant.
59. The Eyeball. The remarkable optical instru-
ment called the eyeball, or the globe of the eye, upon
which sight depends, is, as the name indicates, spherical in
shape. It is not a perfect sphere, since the front part pro-
jects somewhat beyond the rest, and at the posterior part
the optic nerve (Fig. 48, N") is united to it, resembling the
junction of the stem with a fruit. In its long diameter,
that is, the horizontal or from side to side, it measures a
little more than an inch ; in other directions it is rather
less than an inch. In structure, the ball of the eye is firm,
and its tense round contour may in part be felt by pressing
the fingers over the closed lids.
/* 60. The eyeball is composed chiefly of three internal,
transparent media, called humors; and three investing
coats, or tunics. The former are the aqueous humor, Fig.
48, A, the crystalline lens L, and the vitreous humor v.
Of these the lens alone is solid. The three coats of the
eyeball are called the sclerotic s, the choroid CH, and the
retina R. This arrangement exists in respect to five-sixths
of the globe of the eye, but in the anterior one-sixth, these
coats are replaced by the cornea c, which is thin and trans-
parent, so that the rays of light pass freely through it, as
through a clear window-pane.
A 61. In shape, the cornea is circular and prominent,
' resembling a miniature watch-glass, about % of an inch
thick. In structure, it resembles horn (as the name signi-
fies), or the nail of the finger, and is destitute of blood-
59. Depcrilv 1 the shape of th" ovob.ill. It? structure.
60. Of what if the eyeball composed!' State how.
61. The shape of the cornea 'i Its structure '* The " white of the eye r
204 THE SPECIAL SENSES.
vessels. The Sclerotic (from scleros, hard) is composed of
dense, white fibrous tissue, and gives to the eyeball its
firmness of figure and its white color; in front, it consti'
tutes the part commonly called "the white of the eye."
It is one of the strongest tissues in the body; it possesses
very few vessels, and is not very sensitive. It affords pro-
tection to the extremely delicate interior parts of the eye ;
and the little muscles which effect its movements are in-
serted into the sclerotic a short distance behind the cornea
(see Fig. 48, Y, z). It is perforated posteriorly to admit the
optic nerve.
k 62. The Choroid is the second or middle coat of the eye-
ball, and lies closely attached to the inner surface of the
sclerotic. Unlike the latter tunic, its structure is soft and
tender, it is dark in color, and possesses a great abundance
of blood-vessels. Its dark color is due to a layer of dark
brown or chocolate-colored cells spread out over its inner
surface. This dark layer serves to absorb the rays of light
after they have traversed the transparent structures in
front of it ; if the rays were reflected from side to side
within the eye, instead of being thus absorbed, confused
vision would result from the multitude of images which
would be impressed upon the optic nerve.
63. This mechanism has been unconsciously imitated by
the opticians, who, when they make a microscope or tele-
scope, take care that the interior of its tube shall be coated
with a thick layer of black paint or lamp-black; for with-
out it, a clear delineation of the object to be viewed is im-
possible. The albinos, in whom these dark cells of the
choroid are wanting, have imperfect vision, especially in
the daytime and in strong lights. The dark cells are also
wanting in white rabbits, and other animals that have red
or pink eyes ; their vision appears to be imperfect in the
presence of a bright light.
62. The second or middle coat of the eyeball ? Its dark color?
63. Similar mechanism in microscopes ? The albinos ?
THE SPECIAL SENSES. 205
64. The Iris. Continuous with the choroid, in the front
part of the globe of the eye, is a thin, circular curtain,
which occasions the brown, blue, or gray color of the eye
in different individuals. On account of the varieties of its
color, this membrane has received the name Iris, which is
the Greek word for " rainbow" (see Fig. 48, i). A front
view of it is shown in Fig. 47. The iris is pierced in its
centre by a round opening, called tine pupil (P), which is
constantly varying in size. In olden times it was spoken
of as the " apple of the eye." The hinder surface of the
iris, except in albinos, has a layer of dark coloring matter
resembling that of the choroid. The iris is a muscular
organ, and contains two distinct sets of fibres; one of which
is circular, while the other radiates outward from the pupil.
The action of these sets of fibres regulates the size of the
pupil ; for when the circular set acts, the pupil contracts,
and when the other set acts, the opening expands. Their
action is involuntary, and depends on the reflex system of
nerves, which causes the contraction of the pupil when a
strong light falls upon the eye, and its expansion when
the illumination is feeble.
65. The iris, accordingly, serves a very useful purpose
in regulating the admission of light to the eye. It, how-
ever, does not act instantaneously; and hence, when we
pass quickly from a dark room into the bright sunlight,
the vision is at first confused by the glare of light, but as
soon as the pupil contracts, the ability to see becomes per-
fect. On the other hand, when we enter a dark apart-
ment, such as a cellar, for a short time we can see nothing
clearly ; but as soon as the pupil expands and admits more
light, we are enabled to distinguish the surrounding ob-
jects. Animals of the cat species, and others which prowl
around after nightfall, are enabled to see in the dark by
64. What is the iris ? Its construction ? How is the size of the pupil regu-
lated ?
65. The admission of light to the eye ? The action of the iris under different
circumstances ? The lustre of the eye, Iiow'affected in youth and old age ?
206 THE SPECIAL SENSES.
having the iris very dilatable. The size of the pupil affects
the lustre of the eye. When it is large, as it usually is dur-
ing youth, the eye appears clear and brilliant ; while in old
age the pupil is small and the eye is dull. The brilliancy
of the eye is in part, at least, dependent upon the reflec-
tion of light from the front surface of the crystalline lens.
66. Certain poisonous vegetables have the property of
causing the pupil to dilate, and have been used in small
doses to increase the beauty of the eye. One of these
drugs has been so largely used by the ladies for this pur-
pose, that it has received the name belladonna, from the
Italian words meaning " beautiful lady." This hazardous
practice has resulted more than once in the death of the
person desiring thus to increase her personal attraction.
The common English name for belladonna is "deadly
nightshade." (In the diagram on page 214 the shape and
relations of the iris are more accurately shown than in the
figure referred to above.)
67. The Retina constitutes the third and inner coat of
the globe of the eye. This, the important part of the eye
that is sensitive to light, is a kind of nervous membrane,
formed by the expansion of the ultimate filaments of the
optic nerve. Its texture is soft, smooth, and very thin;
it is translucent and of an opaline, or grayish-white
color. It is sensitive to light alone ; and if any form of
mechanical irritation be applied to it, the sensations of
touch and pain are not experienced, but flashes of fire,
sparks, and other luminous appearances are perceived.
Thus an electric shock given to the eye-ball occasions a
flash of light; and a sudden fall, or a blow upon the eye,
is often apparently accompanied by the vision of "stars."
68. These phenomena are due to what is termed the
66. Means used to increase the beauty of the eye? The injurious conse
qiumces *
67. What part does the retina constitute ? How formed ? Its texture ? Color ?
Sensitiveness ?
68. Specific energy of the optic nerve ? Trial in Germany ?
THE SPECIAL SENSES. 207
" specific energy" of the optic nerve, which nerve, in com-
mon with the other nerves of special sense, obeys a general
law of nature, which requires that, whenever one of these
nerves is stimulated, it shall respond with the sensation
peculiar to itself. These flashes of retinal light have no
power to illuminate external objects, although the opposite
of this statement has been maintained. On the occasion
'of a remarkable trial in Germany, it was claimed by a per-
son who had been severely assaulted on a very dark night,
that the flashes of light caused by repeated blows upon the
head enabled him to see with sufficient distinctness to
recognize his assailant. But the evidence of scientific
men entirely refuted this claim, by pronouncing that the
eye, under the circumstances named, was incapacitated for
vision. Too intense light occasions a feeling of pain, but
it is of a peculiar kind, and is termed "dazzling."
69. All parts of the retina are not equally sensitive, and
singularly enough, the point of entry of the nerve of sight,
in the back part of the eyeball, is entirely insensible to light,
and is called the " blind spot." The existence of this point
may be proven by a simple experiment. Hold the accom-
FIG. 49.
panying figure, on page 207, directly in front of and paral-
lel with the eyes. Close the left eye, and fix the sight
steadily on the left-hand circle ; then, by gradually varying
the distance of the figure from the eye, at a certain dis-
tance (about six inches), the right-hand circle will disappear,
69. Sensitiveness of all parts of the retina? Experiment to prove the existr
ence of the "blind spot."
208 THE SPECIAL SENSES.
but nearer or further than that, it will be plainly seen.
The other eye may be also tried, with a similar result : if
the gaze be directed to the right-hand circle, the left one
will seem to disappear. The experiment may be repeated
by using two black buttons on the marble top of a .bureau,
or on some other white surface. The blind spot does not
practically interfere with vision, since the eye is seldom
fixed immovably on an object, and the insensitive parts of
the two eyes can never be directed upon the same object at
the same time.
70. Impressions made upon the retina are not at once
lost, but persist a measurable length of time, and then
gradually fade away. Thus, a bright light or color, gazed
at intently, cannot be immediately dismissed from sight by
closing or turning away the eyes. A stick lighted at one
end, if whirled around rapidly in the dark, presents the
appearance of an unbroken luminous ring; and the spokes
of a rapidly revolving carriage-wheel seem to be merged
into a plane surface. If an object move too rapidly to pro-
duce this sort of lasting impression, it is invisible, as in the
case of a cannon-ball passing through the air in front of
us.
71. If a card, painted with two primary colors as red and
yellow be made to rotate swiftly, the eye perceives neither
of them distinctly ; but the card appears painted with their
secondary color orange. The average duration of retinal
images is estimated at one-eighth of a second ; and it is
because they thus endure, that the act of winking, which
takes place so frequently, but so quickly, is not noticed and
does not interrupt the vision. The retina is easily fatigued
or deprived of its sensibility. After looking steadfastly at
a bright light, or at a white object on a black ground, a
dark spot, corresponding in shape to the bright object,
70. Duration of impressions npon the retina ? How illustrated ?
71. What further illustration? Winking, why it is not noticed. Ease wit'
which the retina is fatigued or deprived of sensibility ? How shown ?
THE SPECIAL SENSES. 209
presents itself in whatever direction we look. This spot
passes away as the retina resumes its activity.
72. If a bright color be gazed at intently, and the eyes
then be turned to a white surface, a spot will appear ; but
its color will be the complement of that of the object. Fix
the eye upon a red wafer upon a white ground, and on re-
moving the wafer a greenish spot of the same shape takes
its place. This result happens because a certain portion of
the retina has exhausted its power to perceive the red ray,
and perceives only its complementary ray, which is green.
The color thus substituted by the exhausted retina is called
a physiological or accidental color. In some persons the
retina is incapable of distinguishing different colors, when
they are said to be affected with " color-blindness." Thus,
red and green may appear alike, and then a cherry-tree,
full of ripe fruit, will seem of the same color in every part.
Railroad accidents nave occurred because the engineer of
the train, who was color -blind, has mistaken the color of a
signal. (Read Note 9, end of Chapter?)
A 73. The Crystalline Lens. Across the front of the
eve, just behind the iris, is situated the Crystalline lens,
enclosed within its own capsule. It is supported in its
place partly by a delicate circular ligament, and partly by
the pressure of adjacent structures. It is colorless and per-
fectly transparent, and has a firm but elastic texture. In
shape it is doubly convex, and may be rudely compared to
a small lemon-drop. The front face of the lens is flatter
than the other, and is in contact with the iris near its
pupillary margin, as is represented in the diagram on page
214. It is only one-fourth of an inch thick.
A 74. When this little body becomes opaque, and no longer
affords free passage to the rays of light, as often happens
72. How further shown? How is the result accounted for? "Color-blind-
ness?"
73. The location of the crystalline lens? How supported? Its color and
texture ? Shape ? Size ?
74. Cataract? Aqueous humor ? Vitreous humor ?
210 THE SPECIAL
with the advance of age, an affection termed " cataract" is
produced. Between the crystalline lens and the cornea is
a small space which contains the aqueous humor (see Fig.
48, A). This humor consists of five or six drops of a clear,
colorless liquid very much like water, as its name implies.
That part of the globe of the eye lying behind the lens is
occupied by the vitreous humor, so called from its fancied
resemblance to melted glass (Fig. 48, v). This humor is a
transparent, jelly-like mass, enclosed within an exceed-
ingly thin membrane. It lies very closely applied to the
retina, or nervous membrane of the eye, and constitutes
fully two-thirds of the bulk of the eyeball.
^ 75. The Uses of the Crystalline Lens. A con-
vex lens has the property of converging the rays of light
which pass through it; and the point at which it causes
PIG. 50. THE RETINAL IMAGE.
them to meet is termed its focus. If a lens of this descrip-
tion, such as a magnifying or burning-glass, be held in
front of an open window, in such a position as to allow
its focus to fall upon a piece of paper, it will be found to
depict upon the paper a miniature image of the scene out-
side of the window. It will be further noticed that the
image is inverted, or upside down, and that the paper
75. What is a lens and its focufl ? i'he miniature image, how produced?
THE SPECIAL SENSES.
at the place upon which the image is thrown is much
brighter than any other part.
76. Now all the transparent structures of the eye, but
especially the crystalline lens, operate upon its posterior
part, or retina, as the convex lens acts upon the paper; that
is, they paint upon the retina a bright inverted miniature
of the objects that appear in front of the eye (Fig. 50).
That this actually takes place may be proved by experi-
ment. If the eyeball of a white rabbit, the walls of which
are transparent, be examined while a lighted candle is held
before the cornea, an image of the candle-flame may be
seen upon the retina.
77. The form and structure of the crystalline lens endow
it with a remarkable degree of refractive power, and en-
able it to converge all the rays of light that enter it
through the pupil, to a focus exactly at the surface of the
retina. When this lens is removed from the eye, as is
frequently done for the cure of cataract, it is found that
the rays of light then have their focus three-eighths of an
inch behind the retina; that the image is four times larger
than in the healthy eye, that it is less brilliant, and that
its outline is very indistinct. From this we learn that one
of the uses of the crystalline lens is to make the retinal
image bright and sharply-defined, at the same time that it
reduces its size. Indeed, the small size of the image is a
great advantage, as it enables the limited surface of the
retina to receive, at a glance, impressions from a consider-
able field of vision.
78. As the image upon the retina is inverted, how does
the mind perceive the object in its true, erect position ?
Many explanations have been advanced, but the simplest
and most satisfactory appears to be found in the fact that
76. How are figures painted upon the retina ? How proved ?
77. What can be said in respect to the form and structure of the crystalline
lens?
78. How is the inverted image upon the retina presented in its true position to
the mind ?
212 THE SPECIAL SENSES.
the retina observes no difference, so to speak, between the
right and left or the upper and lower positions of objects.
In fact, the mind is never conscious of the formation of a
retinal image, and until instructed, has no knowledge that
it exists. Consequently, our knowledge of the relative
location of external objects must be obtained from some
other source than the retina. The probable source of this
knowledge is the habitual comparison of those objects with
the position of our own bodies: thus, to see an elevated
object, we know we must raise the head and eyes ; and to
see one at our right hand, we must turn the head and eyes
to the right.
79. Long-sight or Hyperopia, and Short-sight
or Myopia. The eye is not in ali cases perfectly
formed. For example, persons may from birth have ths
comea too prominent or too flat, or the lens may be too
th ick or too thin. In either of these conditions sight will
FIG. SI. THE DIFFERENT SHAPES OF THE GLOBE OF THE EYB.
N, The Natural Eye. M, The Short-sighted Eye.
H, The Long-sighted Eye. S, Parallel Rays from the Sun.
be more or less defective from the first, and the defect will
not tend to disappear as life advances. The most common
imperfection, however, is in the shape of the globe ; which
may be short (Fig. 5j., H), as compared with the natural
eye, K, or it may be too long, M.
80. When the globe is short, objects can only be clearly
79. The uniform perfection of the eye? Examples? The most common im-
perfection?
80. How is " Ions-sight 11 explained ? " Short-sight ?"
THE SPECIAL SENSES. 213
seen that are at a distance, and the condition of the vision
is known as "long-sight," or hyperopia. It will be ob-
served, by reference to Fig. 51, that the focus of the
rays of light would fall behind the retina of this eye.
When the globe is too long, objects can only be clearly seen
that are very near to the eye; and the condition resulting
from this defect is termed "short-sight," or myopia. The
focus of the rays of light is, in this case, formed in the
interior of the eye in front of the retina.
81. Long-sight, or hyperopia, is common among school-
children, nearly as much so as short-sight, and must not be
confounded with the defect known as the "far sight" of
old people; although in both affections the sight is im-
proved by the use of convex glasses. Children not infre-
quently discover that they see much better when they
chance to put on the spectacles of old persons. For the
relief of short-sight, concave glasses should be employed;
as they so scatter the rays of light as to bring the focus to
the retina, and thus cause the vision of remote objects
to become at once distinct. That form of "squint," in
which the eyes are turned inward, is generally dependent
upon long-sight, while that rarer form, when they turn
outward, is due to short-sight. (Read Note 5.)
82. The Function of Accommodation. If, after
looking through an opera-glass at a very distant object, it
is desired to view another nearer at hand, it will be found
impossible to obtain a clear vision of the second object un-
less the adjustment of the instrument is altered; which is
effected by means of the screw. If an object, like the end of
a pencil, be held near the eye, in a line with another object
at the other side of the room, or out of the window, and
the eye be fixed first apon one and then upon the other, it
will be found that when the pencil is clearly seen, the fur-
8 1 . Lon<r-sight, how common ? With what must it not be con ounded ? Kind
of glasses for short-sight ? Why ? Squint ?
82. What is stated in connection with the opera-glass? Experiment with
pencil and distant object?
214 THE SPECIAL SENSES.
ther object is indistinct; and when the latter is seen
clearly, the pencil appears indistinct ; and that it i im-
possible to see both clearly at the same time. Accordingly,
the eye must have the capacity of adjusting itself to dis-
tances, which is in some manner comparable to the action
of the screw of the opera-glass.
83. This, which has been called the function of accom-
modation, is one of the most admirable of all the powers
of the eye, and is exercised by the crystalline lens. It
consists essentially in a change in the curvature of the
front surface of the lens, partly through its own elasticity,
and partly through the action of the ciliary muscle.
JiJiG. 52.- THE FUNCTION OF ACCOMMODATION.
The right half of the diagram shows the eye at rest. The left half shows the lens
accommodated for near vision.
When the eye is at rest, that is, when accommodated for &
distant object, the lens is natter and its curvature dimin-
ished (see Fig. 52) ; but when strongly accommodated for
near vision the lens becomes thicker, its curvature in-
creases, and the image on the retina is made more sharp
and distinct. Since a strong light is not required in view-
ing near objects, the pupil contracts, as is shown in the
left-hand half of the diagram.
83. Function of accommodation ? In what does it consist ? How is the func-
tion explained ?
THE SPECIAL SENSES. 215
84. Old-sight, or Presbyopia. But this marvel-
lously beautiful mechanism becomes worn with use; or,
more strictly speaking, the lens, like other structures of the
body, becomes harder with the approach of old age. The
material composing the lens becomes less elastic, the power
to increase its curvature is gradually lost, and as a conse-
quence, the person is obliged to hold the book further away
when reading, and to seek a stronger light. In a word, the
function of accommodation begins to fail, and is about the
first evidence that marks the decline of life. By looking at
the last preceding diagram, and remembering that the in-
creased curvature of the lens cannot take place, it will be
at once understood why old-sight is benefited in near
vision by the convex lens, such as the spectacles of old
people contain. It acts as a substitute for the deficiency
of the crystalline lens.
85. The Sense of Hearing. Sound. Hearing, or
audition, is the special sense by means of which we are
made acquainted with sound. What is* sound? It is an
impression made upon the organs of hearing, by the vibra-
tions of elastic bodies. This impression is commonly prop-
agated by means of the air, which is thrown into delicate
undulations, in all directions from the vibrating sub-
stance. When a stone is thrown into smooth water, a wave
of circular form is set in motion, from the point where the
stone struck, which constantly increases in size and dimin-
ishes in force, as it advances.
86. Somewhat resembling this, is the undulation, or
sound-wave, which is imparted by a sonorous vibration to
the surrounding atmosphere. Its shape, however, is spher-
ical, rather than circular, since it radiates upward, down-
ward, and obliquely as well as horizontally, like the wave
84. Change of sight with the approach of old age ? Explain the change ?
85. Hearing or audition? What is sound? How propagated commonly?
Stone thrown in water ?
86. Sound-wave in the atmosphere? Its shape? Rate of motion ? Sound, in
water, air, and solid bodies ?
216 THE SPECIAL SENSES.
in water. The rate of motion of this spherical wave of
air is about 1050 feet per second, or one mile in five
seconds. In water, sound travels four times as fast as in
air, and still more rapidly through solid bodies ; along an
iron rod, its velocity is equal to two miles per second.
87. The earth, likewise, is a good conductor of souna
It is said that the Indian of our western prairies can, by
listening at the surface of the ground, hear the advance of
a troop of cavalry, while they are still out of sight, and
can even discriminate between their tread and that of a
herd of buifaloes. Solid substances also convey sounds
with greater power than air. If the ear be pressed against
one end of a long beam, the scratching of a pin at the
other extremity may be distinctly heard, which will not be
at all audible when the ear is removed from the beam.
Although air is not the best medium for conveying sound,
it is necessary for its production. Sound cannot be pro-
duced in a vacuum, as is shown by ringing a bell in the
exhausted receiver of an air-pump, for it is then entirely
inaudible. But let the air be readmitted gradually, then
the tones become more and more distinct, and when the
receiver is again full of air, they will be as clear as usual.
88. All sonorous bodies do not vibrate with the same
degree of rapidity, and upon this fact depends th<? pitch of
the sounds that they respectively produce. Thfc more fre-
quent the number of vibrations within a given time, the
higher will be the pitch ; and the fewer their number, the
lower or graver will it be. Now, the rate of the successive
vibrations of different notes has been measured, and it has
thus been found that if they are less than sixteen in a
second, no sound is audible; while if they exceed 60,000
per second the sound is very faint, and is painful to the
87. The earth as a conductor of sound ? To what has the western Indian been
taught ? Solid substances as conductors ? AS regards sound, in what respect is
air necessary ? Sound in a vacuum ?
THE SPECIAL SENSES.
ear. The extreme limit of the capacity of the human ear
may be considered as included between these points; but
the sounds which we ordinarily hear are embraced be-
tween 100 and 3,000 vibrations per second.
89. The ear, which is the proper organ of hearing, is the
most complicated of all the structures that are employed
in the reception of external impressions. The parts of
which it is composed are numerous, and some of them are
extremely small and delicate. Nearly all these parts are
located in an irregularly shaped cavity hollowed out in the
temporal, or " temple," bone of each side of the head.
That part of the bone in which the auditory cavity is
placed has the densest structure of all bones of the body,
and has therefore been called the "petrous," or rocky part
of the temporal bone. In studying the ear, it is necessary
to consider it as divided into three portions, which are
called, from their relative positions, the external ear, the
middle ear, and the internal ear. (In the diagram, Fig. 53,
A, the first is not shaded, the second is lightly shaded, and
the last has a dark background.)
90. The External Ear. The external portion of the
organ of hearing, designated in Fig. 53, A, includes, first,
that outer part (a), which is commonly spoken of as " the
ear," but which in fact is only the portal of that organ ;
and, secondly, the auditory canal (b). The former consists
of a flat flexible piece of cartilage, projecting slightly from
the side of the head, attached to it by ligaments, and sup-
plied with a few weak muscles. Its surface is uneven, and
curiously curved, and from its resemblance to a shell, it
has been called the concha. It probably serves to collect
sounds, and to give them an inward direction ; although
its removal is said not to impair the acuteness of hearing
more than a few days.
90. Of what does the external portion of the organ of hearing consist ? De-
scribe the portal of that organ known as the ear. Its use ?
218
THE SPECIAL SENSES.
91. In those animals whose hearing is more delicate
than that of man, the corresponding organ is of greater
importance, it being larger and supplied with muscles of
greater power, so that it serves as a natural kind of ear-
trumpet, which is easily movable in the direction of any
sound that attracts the attention of the animal. Bold,
predaceous animals generally have the concavity of this
PIG. 53. THE EAR AND ITS DIFFERENT PARTS.
A, Diagram of the Ear.
o, 6, External Ear. d, Middle Ear.
c, Membrane tympani. e. Internal Ear.
B to E'", Bones of the Middle Ear (magnified).
C, The Labyrinths, or Internal Ear (highly magnified).
organ directed forward, while in timorous animals, like the
rabbit, it is directed backward. Fishes have no outer ear,
but sounds are transmitted directly through the solid bones
of the head, to the internal organ of hearing.
- 92. The auditory canal (Fig. 53, A, #), which is con
tinuous with the outer opening of the ear, is a blind pas-
sage, an inch and a quarter in length, its inner extremity
being bounded by a closely-fitting, circular membrane.
This canal is of oval form, is directed forward and inward,
9 1 . The ear in the animal? of delicate hearing ? Rabbit ? Fishes 1
92. What is the auditory canal ? Describe it.
THE SPECIAL SENSES. 219
and is slightly curved; so that the inner end is ordinarily
concealed from view. The pouch of the skin which lines
this passage is smooth and thin, especially at the lower
end, where it covers the membrane just mentioned.
93. As in the case of the nostrils, a number of small,
stiff hairs garnish the margin of the auditory canal, and
guard it, to some extent, against the entrance of insects
and other foreign objects. The skin, too, covering its outer
half, is furnished with a belt of little glands which secrete
a yellow, viscid, and bitter substance, called " ear-wax,"
which is especially obnoxious to small insects. As the
outer layer of this wax-like material loses its useful pro-
perties, it becomes dry, and falls out of the ear in the form
of minute, thin scales, a fresh supply being furnished from
the little glands beneath. In its form, the auditory canal
resembles the tube of an ear-trumpet, and serves to convey
the waves of sound to the middle portion of the ear.
94. The Middle Ear, or Tympanum. The middle
ear is a small cavity, or chamber, of irregular shape, about
one-fourth of an inch across from side to side, and half an
inch long (see Fig. 53, A, d). From the peculiar arrange-
ment of its various parts it has very properly been called
the tympanum, or the "drum of the ear." The middle
ear, like the external canal, contains air.
95. The circular membrane, already mentioned as clos-
ing the auditory canal, is the partition which separates
the middle from the external ear, and is called the mem-
brana tym,pani (c), and may be considered as the outer head
of the drum of the ear. It is sometimes itself spoken of as
the " drum," but this is incorrect ; since a drum is not a
membrane, but is the hollow space across which the mem-
brane is stretched. This membranous drum-head is very
tense and elastic, and so thin as to be almost transparent ;
93. How is it guarded and protected ? Ear-wax ?
94. What is the middle ear ? Why called tympanum?
95. What is the membrana tympani ? Describe it.
220 THE SPECIAL SENSES.
its margin is fastened into a circular groove in the adjacent
bone. Each wave of sound that impinges against this
delicate membrane causes it to vibrate, and it, in turn,
excites movements in the parts beyond.
96. Within the tympanum is arranged a chain of re-
markable " little bones," or ossicles. They are chiefly three
in number, and from their peculiar shapes bear the follow-
ing names: malleus, or the mallet; incus, or the anvil;
and stapes, or the stirrup. A fourth, the smallest bone in
the body, in early life intervenes between the incus and
stapes, but at a later period it becomes a part of the incus.
It is called the orbicular bone. Small as are these ossicles
and they, together, weigh only a few grains they have
their little muscles, cartilages, and blood-vessels, as per-
fectly arranged as the larger bones of the body. One end
of the chain of ossicles, the mallet, is attached to the mem-
brane of the tympanum, or outer drum-head, while the
other end, the stirrup, is firmly joined by its foot-piece to
a membrane in the opposite side of the cavity. The chain,
accordingly, hangs suspended across the drum between the
two membranes ; and when the outer one vibrates under
the influence of the sound-wave, the chain swings inward
and transmits the vibration to the entrance of the inner
ear.
97. The musical instrument, the drum, is not complete
if the air within be perfectly confined : we therefore find in
all instruments of this kind a small opening in the side,
through which air may pass freely. By this means the
pressure of the air upon the vellum which forms the head
of the drum is made equal upon all sides, and the resonance
of the drum remains unaffected by the varying density of
the atmosphere. It will, therefore, emit its proper sound,
whether it be struck in the rarified air of the mountain-
top, or in the condensed air of a mine. The tympanum,
96. What are the ossicles ? Their number and names ? Their arrangement ?
97, The Euetachian tube ? Describe it, and state its use.
THE SPECIAL SENSES.
221
or drum of the ear, in like manner has an opening by
means of which it communicates freely with the external
air. This opening is a narrow canal, about an inch and a
half long, called the Eustachian tube, after the name of its
discoverer, Eustachius.
98. The course of this passage is indicated in Fig. 54, i,
directed downward and inward : its other extremity opens
into the upper part of the throat. The passage itself is
FIG. 54. SECTION OF THE RIGHT EAR.
A, The Concha. E, Incus, or Anvil.
B, Auditory Canal. M, Malleus, or Mallet.
C, Membrane of the Drum, I, Eustachian Tube.
(the lower half.) G, Semicircular Canals.
D, A small muscle. H, Cochlea, or snail's shell.
ordinarily closed, but whenever the act of swallowing or
gaping takes place, the orifice in the throat is stretched
open, and the air of the cavity of the tympanum may then
be renewed. Air may at will be made to enter through
this tube, by closing the mouth and nose, and then trying
98. What can you state of the action of the Eustachian tube ?
222 THE SPECIAL SENSES.
to force air through the latter. When this is done, a dis-
tinct crackle or clicking sound is perceived, due to the
movement of the membranes, and of the little bones of the
ear.
99. The Eustachian tube serves, also, as an escape-pipe
for the fluids which form wi h'n the middle ear; and
hence, when its lining membrane becomes thickened, in
consequence of a cold, or sore throat, and the passage is
thus more or less choked up, the fluids are unable to escape
as usual, and therefore accumulate within the ear. When
this takes place, the vibrations of the membrane are inter-
fered with; the sounds heard appear muffled and indis-
tinct; and a temporary difficulty of hearing, which is
known as "throat-deafness," is the result. This result re-
sembles the effect produced by interrupting the vibrations
of a sonorous body, such as all are familiar with ; if the
finger be placed upon a piano-string or bell when it is
struck, the proper sound is no longer fully and clearly
emitted. But the primary use of this tube is to afford a
free communication between the middle ear and the exter-
nal atmosphere, and thus secure an equal pressure upon
both sides of the membrane of the drum of the ear, however
the density of the atmosphere may vary. If, from undue
tension of the membranes, pain is experienced in the ears,
when ascending into a rare atmosphere, as in a balloon, or
descending into a dense one, as in a diving-bell, it may be
relieved by repeating the act of swallowing, from time to
time, in order that the inner and outer pressure may thus
be promptly equalized.
K 100. The Internal Ear, or Labyrinth. The most
' essential part of the organ of hearing is the distribution of
the auditory nerve. This is found within the cavity of the
internal ear, which, from its exceedingly tortuous shape,
99. What other purpose doe? the Enstaohian tube serve * How is this shown 1
" Throat-deafness ?" Primary use of the Eustachian tube ?
100. The essential part of the organ of hearing ? Its location ? Formation *
THE SPECIAL SENSES. 223
has been termed the labyrinth (see Fig. 53, c). This
cavity is hollowed out in dense bone, and consists of three
parts ; the vestibule (a), or ante-chamber, which is connected
with the other two ; the cochlea (b), or snail's shell ; and the
three semicircular canals (c). The manner in which the
nerve of hearing is distributed is remarkable, and is pecu-
liar to this nerve. In the vestibule and the canals its
fibres are spread out over the inner surface, not of the bony
cavity but of a membranous bag, which conforms to and
partially fills that cavity; and which floats in it, being
both filled and surrounded with a clear, limpid fluid.
101. A singular addition to the mechanism of hearing is
observed within this membranous bag of the labyrinth
This consists of two small oval ear-stones, and a quantity
of fine powder of a calcareous nature, which is called "ear-
sand." When examined under the microscope, these sandy
particles are seen to lie scattered upon and among the
delicate filaments of the auditory nerve; and it is probable,
that as the tremulous sound-wave traverses the fluid of the
vestibule, the sand rises and falls upon the nerve filaments,
and thus intensifies the sonorous impression.
102. In the cochlea, or snail's shell, which contains the
fluid, but no membrane, the nerve ramifies upon a spiral
shelf, which, like the cochlea itself, takes two and a half
turns, growing continuously smaller as it winds upward.
As many as three thousand nerve fibres of different lengths
have been counted therein ; which, it has been thought,
form the grand, yet minutely small key-board, upon which
strike all the musical tones that are destined to be con-
veyed to the brain. The vestibule, it is also supposed, takes
cognizance of noise as distinguished from musical sounds ;
while the office of the semicircular canals is, in part at
least, to prevent internal echoes, or reverberations.
101. Where is the "ear-sand" found ? Give the theory as to its use.
102. In the cochlea or snail's shell ? "Key-board 1 ' in the internal ear? The
vestibules ? Semicircular canals ?
224 THE SPECIAL SENSES.
103. The vestibule communicates with the chain of
bones of the middle ear by means of a small opening,
called the " oval window," or fenestra ovalis. Across this
window is stretched the membrane, which has already
been alluded to as being joined to the stirrup-bone of the
middle ear. Through this window, then, the sound-wave,
which traverses the external and middle ear, arrives at last
at the labyrinth. The limpid fluid which the latter con-
tains, and which bathes the terminal fibres of the nerve of
hearing, is thus agitated, the nerve-fibres are excited, and
a sonorous impression is conducted to the brain, or, as we
say, a sound is heard.
104. Protection of the Sense of Hearing. From
what has been seen of the complicated parts which com-
pose the organ of hearing, it is evident that while many
of them possess an exquisite delicacy of structure, Nature
has well and amply provided for their protection. We
have observed the concealed situation of the most impor-
tant parts of the mechanism of the ear, the length of its
cavity, its partitions, the hardness of its walls, and its
communication with the atmosphere ; all these provisions
rendering unnecessary any supervision or care on our part
in reference to the interior of the ear. But in respect to
its external parts, which are under our control and within
the reach of harm, it is otherwise. We may both observe
the dangers which threaten them, and learn the means
necessary to protect them.
105. One source of danger to the hearing consists in
lowering the temperature of the ear, especially by the
introduction of cold water into the auditory canal. Every
one is familiar with the unpleasant sensation of distension
and the confusion of sounds which accompany the filling
of the ear with water when bathing : the weight of the
103. With what does the vestibule communicate? What is the theory bv
which sound is conducted to the brain ?
104. The formation of the organ of hearing with a view to its protection?
105. Danger to which the hearing may be subjected ? Advice ?
THE SPECIAL SENSES. 225
water within it really distends the membrane, and the cold
chills the adjacent sensitive parts. It is not surprising,
therefore, that the frequent introduction of cold water and
its continued presence in the ear enfeeble the sense of
hearing. Care should be taken to remove water from the
ear after bathing, by holding the head on one side, and,
at the same time, slightly expanding the outer orifice, so
that the fluid may run out. For a like reason, the hair
about the ears should not be allowed to remain wet, but
should be thoroughly dried as soon as possible.
106. It may be stated as a general rule, to which there
are but few exceptions, that no cold liquid should ever be
allowed to enter the ear. When a wash or injection is
rendered necessary, it should always be warmed before use.
The introduction of cold air is likewise hurtful, especially
when it pours through a crevice directly into the ear, as it
may often do through the broken or partially closed win-
dow of a car. The avoidance of this evil gives rise to
another almost as great ; namely, the introduction of cot-
ton or other soft substances into the ear to prevent it from
" catching cold." This kind of protection tends to make
the part unnaturally susceptible to changes of tempera-
ture, and its security seems to demand the continued pres-
ence of the "warm" covering. As a consequence of its
presence, sounds are not naturally conveyed, and the sen-
sitiveness of the nerve of hearing is gradually impaired.
107. The chief source of injury, however, to the ear is
from the introduction of solid substances into the auditory
canal, with the design of removing insects or other foreign
objects that have found their way into the ear ; or with
the design of scraping out the ear-wax. For displacing a
foreign object, it is usually sufficient to syringe the ear
gently with warm water, the head being so held that the
1 06. The general rule as to the use of water for the ear ?
107. Chief source of injury to the
jccte from the ear ? Of a live insect f
107. Chief source, of injury to the ear? Directions for removing foreign ob-
"ive insect f
226
THE SPECIAL SENSES.
fluid easily escapes. If a live insect has gained entrance
to the ear, it may first be suffocated by pouring a little oil
upon it, and afterward removed by syringing the ear as
just mentioned.
108. The removal of ear-wax is generally unnecessary ;
for, as we have before seen, Nature provides that the excess
of it shall become dry, and then spontaneously fall out in
the form of fine scales. The danger from the introduction
of solid implements into the outer ear is chiefly found in
the fact that the membrane which lies at the bottom of it
is very fragile, and that any injury of it is liable to be per-
manent, and to permanently impair the hearing of the
injured ear. (Read Note 10, end of Chapter)
QUESTIONS FOR TOPICAL REVIEW.
Give as full statements as you can, on the following subjects :
1. Production of sensation.... 177, 178
2. Variety of sensations 178, 179
3. General sensibility 179, 180
4. The sensation of pain 180
5. The uses of pain 180, 181, 182
6. Special sensation 182, 183
7. Organs of touch 183, 184
8. The sense of touch 184, 185, 186
9. The delicacy of touch 186. 187
10. Sensations of Temperature and
weight 187, 188
11. The organ of taste 188, 189
12. The sense of taste 189, 19')
13. Relations of taste, etc 190, 191
14. Influence of education, etc.. 191, 192
15. The sense of smell 192, 193
16. The nerve of smell 193, 194
17. Uses of the sense of smell. .194, 195
18. The sense of sight 196, 197
19. Light, and the optic nerve.. 197, 198
20. The organ of sight 198, 199
21. The orbits 199
22. The eyelids 200, 201
23. The lachrymal fluid 201, 202, 203
24. The eyeball 203 204
25. The iris 205, 206
26. The retina 206, 207, 208, 209
27. The crystalline lens 209, 210
28. Uses of the lens 210, 211, 212
29. Loner and short sight 212, 213
30. Function of accommodatioii.213, 214
31. Old sight, or presbyopia 215
32. Hearing and sound 215.216, 217
33. The external ear 217,218, 213
34. The middle ear 219-222
35. The internal ear 222. 223, 224
36. Protection of the sense of hear-
ing 2^4,225, 220
NOTES.
1. Pain is Nature's Harbinger of mischief" (p. 182, ^ 13). "It
must, therefore, be evident that pain is, under certain circumstances, really bene-
ficial. It is often a great boon to have a sensitive stomach ; for those who suffer
pain after food are less apt habitually to err in diet, and thus to become dyspeptic
or gouty, than those whose organs receive everything uncomplainingly. Pain in the
stomach is frequently due (in well-to-do people) to the fact that they won't work
and will eat ; not that the stomach itself is weak (as they think), but that, the
supply of food being greater than the demand, the system becomes overstocked.
In dyspepsia the cause is very often far away, aud the stomach is no more the
cause of the malady than the big toe is of the gout ; but if the stomach gave no
signs of perturbation, the evil would be allowed longer to exist unnoticed. We
should always give early attention to pain, and discover its causes before they
become too complex to be unravelled, and before the derangement which its pres-
ence indicates becomes permanent. " The following incident well illustrates the
extent to which pain may be dependent on fancy : ' A butcher was brought into a
druggist's from the market-place opposite, laboring under a terrible accident.
The man, on trying to hook up a heavy piece of meat above his head, slipped,
and the sharp hook penetrated his arm so that he himself was suspended. On
being examined, he was pale, almost pulseless, and expressed himself as suffering
acute agony. The arm could not be moved without causing excessive pain ; and
in cutting off the sleeve he frequently cried out ; yet when the arm was exposed, it
was found quite uninjured, the hook having only traversed the sleeve of the coat ! '
The sensation here was perfectly real, but originated in a change in the brain and
nerves, instead of in the external senses." Notes on Pain.
2. Flavors and the Sense of Taste (p. 190, 1 33). "The cause and.
intimate nature of tastes are no better understood than those of odors. Flavors
elude analysis and defy classification, even that which divides them into agreeable
and disagreeable, for the taste of individuals and of nations singularly differs in
this respect. The Laplander and the Esquimaux drink great quantities of train-oil,
which for them is a greatly-esteemed article of food, and is most admirably adapt-
ed to the exigencies of a Polar climate ; the Abyssinians eat raw flesh, and find
its flavor excellent, while the inhabitant of the West partakes of it with the great-
est repugnance, and only as a medicine. Oysters, which are so generally esteemed
in our country, are to some persons disagreeable and nauseous ; and truffles, the
delight of the gourmand, are rejected by the uninitiated on account of their flavor
and their perfume. It is the same with almost all alimentary substances; they
are eagerly sought after by some, and despised or abhorred by others. Let us
remember the proverb ' de gustibm non disputandumS and not dispute in regard
to tastes; each is suited to its own country, and goodly numbers acclimatize
themselves, to the great advantage of peoples among whom at first they seem
exceedingly strange. Man should control his taste, and habituate it to all whole-
some aliment ; this neither excludes choice, nor blunts the delicacy of the sense;
and while we resist its seductions, we should give timely heed to its instincts and
its counsels, for they are often invaluable. 1 ' The Wonders of the Human Body.
3. The Protective Function of the Sense of Smell (p. 195, t 43).
" Smell seems to be regarded as an endowment bestowed simply for pleasure,
serving to promote no important or vital end. That its main use is to signal dan-
ger to internal parts is not duly appreciated. The detection of an offensive odor
is thought to be the only bad thing about it, and which, to those habituated to it,
is of no subsequent importance, Men even pride themselves on becoming accus-
tomed to offensive odors, and quite enjoy the sight of one whose nerve of smell is
NOTES.
not benumbed like tbeir own. Instead of seeking to blunt the sensibilities of
this nerve, it should be a study to improve it, as the most delicate and available
test of air impurity ; far superior, under ordinary circumstances, to the tests of
science. In this way, all ordinary atmospheric impurities may be quickly detected;
and it is truly remarkable how, by a little attention, this sense can be so improved
as to detect instantly even slight impurities to which it had before been insensible.
In many houses, by the total neglect of this sense, there is an ever-present/ami/y
odor, produced by some special kind of household impurity, and of which the in-
mates do not seem to be aware. To those accustomed to pure air, house odors
are always perceptible and disagreeable. This ought to be accepted as sufficient
evidence of their unhealthful tendencies; not perhaps of an instant or violent
sort, yet enough so to give rise to many sensations of slight discomfort, and pro-
ducing, when long continued, a state of the body very favorable to the beginning
and growth of virulent diseases." Black's Ten Laws of Health.
4. The Effects of Certain Odors (p. 196, t 44). " I have not seen it any-
where laid down as a general rule, but I believe it might be affirmed, that we are
intended to be impressed only sparingly and transiently by odor. There is a pro-
Vision for this in the fact that all odors are vapors or gases, or otherwise volatile
substances; so that they touch but the inside of the nostril, and then pass away.
"In conformity with this fleeting character of odorous bodies, it is a law in
reference to ourselves, to which as far as I know, there is no exception, that there
is not any substance having a powerful smell of which it is safe to take much in-
ternally. The most familiar poisonous vegetables, such as the poppy, hemlock,
henbane, monk's-hood, and the plants containing pruseic acid, have all a strong
and peculiar smell. Nitric, muriatic, acetic and other corrosive acids, have
characteristic potent odors, and all are poisons. Even bodies with agreeable
Odors, like oil of roses, or cinnamon, or lavender, are wholesome only in very
small quantities, and, when the odor is repulsive, only in the smallest quantities.
So far as health is concerned, the nostril should be but sparingly gratified with
pleasing odors, or distressed by ungrateful ones. No greater mistake can be
made in sick rooms than dealing largely in aromatic vinegar, eau de cologne, lav-
ender water, and other perfumes. This hiding of one odor by another, is like
trying to put away the taste of bitter aloes by that of Epsom salts. Physical
comfort is best secured by rarely permitting an infraction of the rule, that the
condition of health is no odor at all. 1 ' Wilson on the Five Gateways of Knowledge.
5. On the Production of Short-Sight (p. 213, 1 81). "The obser-
vations of Cohn in the schools and University of Breslau, of Kruger in Frankfort-
on-the-Main , of Erismann, in St. Petersburgh, of Von Hoffmann in Wiesbaden,
and others abroad, prove most conclusively that one of the bad effects of school
and college life is to produce diseases of the eyes. They have shown that near-
sightedness increases rapidly in frequency as you go up in the scale of schools
from the primaries of the rural district s to the universities. The gravity of this
findingmay be appreciated when we remember that near-sightedness is a disease,
and that it very frequently descends from one generation to another, marked by
such organic changes in the eyes as tend to the production of the worst forms of
the malady and to blindness. In 1867, Cohn, of Breslau, published the results of
the examination of the eyes of 10,060 scholars. His examinations covered the
entire range of school-life. He found that 1,750 of the 10,060 children had defec-
tive vision, about seventeen per cent. He also examined, without selection, 410
of the 964 students of the Breslau University, and found that not one-third had
normal eyes." Dr. C. R. Agnew.
NOTES.
6. The Mutual Relations of the Special Senses (p. 182, T 15). " A
blind man attempting to express his notion of scarlet, said it resembled the sound
of a trumpet. We are constantly reminded of the impressions of one sense by
the operations of another. To my ear the bass note in music is what a dull black
is to the eye. The reverberations of deep thunder seem like boulders with worn
angles, with profiles blunt and irregular, as if drawn by the jerking pencil of the
lightning ; and one who never had the pleasure of seeing stars from a blow on the
head, may get a tolerably correct idea of that kind of galaxy by snuffing at a bottle
of volatile salts.
" Language is full of effort to report the impressions of one sense by the sym-
bols of another. We say that an apple is sweet, that a rose is swee', a lace is
sweet, a strain of music is sweet, and love is sweet, not to mention the saccharine
reaction of the k uses of adversity.' Here taste, smell, sight, hearing, and a social
sentiment, use the same word lor that pleasurable sensation experienced by the
mind through each distinctive organ. We assist the organ of one sense by that of
another. We open the lips and part the teeth a little when we are eager to hear ;
we listen and turn the eyes' attention inward, when we would detect a delicate
taste, or remember a faded impression.
" But this mutual accommodation of the senses is not so marvelous as it may
seem, when we remember that the whole five, six, or seven, as you please, are
but one power of nervous perception, specialized into a variety of functions,
differentiated, as the learned say, that we may have more perfect work by a
division of labor. The same necessity which developed nerve-contact into sight
on the one hand, and hearing on the other, might also express through one of
these the sensations proper to the other, when the other was wanting. Seal up
the eyes of a bat, say the naturalists, and let it loose in a room crossed with wires
in every direction, and he will fly clear of them all, as if he had other means of
perception as sensitive as the optic nerve.
"Laura Bridgman, with neither sight, hearing, nor smell, could detect the
presence of a stranger in the room, without contact. Her mind then must have
as distinct an image of every person as we have, yet not one of what we call our
senses could go to the making up of that image. It could not be form as we know
it, nor a voice, nor an odor, but it was itself other than all, exciting emotions of
love or hate, gratitude or repugnance, and the thought it excited must have had
shape, though it is not easy to imagine how." The Schoolmaster.
7. Variation in Structure in the Nerves of Special Sense (p. 183,
1" 16.) u While in the more intellectual senses Sight, Hearing and Touch the
nerves have their protecting and isolating sheaths corresponding with the dis-
tinctness and separateness of the parts of the impression, in Smell, the nerves are
a plexus of unsheathed fibres, corresponding with the fusion of the odorous
impression into one whole, without distinction of parts." Herbert Spencer.
8. Qualities Determined by the Sense of Touch (p. 188, 127.) "The
eye, by the aid of certain signs, is often able to tell whether a body is hot when,
for instance, it is glowing or steaming but a perception of warmth is not possessed
by the eye. This is had by the skin alone, and it is of great importance to our
preservation that this property is spread over the entire surface ; for it surrounds
the body like a protecting wall against its worst enemy cold, which if not
thus guarded against at all points, would speedily destroy 'life. We are warned,
however, of the approach of the enemy by a common sensation of the skin, and
an inward chill, which is only caused by a coolness of the skin. The skin, in like
manner, protects the body against the approach of a hurtful degree of heat. Thus,
you see, the skin has certain qualities of sensation. Just as in the eye, in looking
at a wafer perceives that it is both red and circular, distinguishing both the cole.
NOTES.
and form of bodies, so the sensitive skin by contact with an object distinguishes
the qualities of form, firmness, hardness, liquidity, pressure and temperature.
* * * "Weber has discovered the interesting fact that warm bodies feel lighter
than cold ones : if a cold coin be placed upon the forehead of some person, whose
eyes are shut, and then upon the same spot two warm coins, the weight would
seem to him the same, whilst he could distinguish correctly in the case of cold
weights. * * * If we place the elbow in hot water we experience heat only
in the part immersed, not in the whole arm, although the nerve just under the
skin runs throughout the arm and hand. What we feel is a dull sense of pain in the
whole arm if the water is too hot. So, too, if the elbow is placed in ice-water the
pain is just the same in the arm ; proving that the nerve-trunk can feel neither
warmth nor cold." Bernstein 1 's Five Senses of Man.
9. Color-blindness (p. 209, 1 72.) " Daltonism, or color-blindness, receives
its name from the eminent English chemist, who described this infirmity as it
existed in his own case. It arises from an unnatural condition of the organs of
vision which prevents the discrimination of certain colors. Some persons will
mistake red for green ; so that ripe cherries on a tree appear the same as the leaves ;
others recognize only black and white. Persons thus affected are sometimes in-
capable of discriminating musical tones." The healthy eye ordinarily fails to dis-
criminate between certain colors, blue and green especially, when viewed by
artificial light. But even this may in a measure be overcome by training ; so that
an expert dealer in silks obtains a knowledge of the shades of blue, green and vio-
let which is proof against the confusing influence of gas-light and tinted curtains.
The eyes of persons who have much to do with colors are more liable to become
overstrained than those dealing chiefly with rays of white light. Flint's Physiology
(in part).
10. How tlie Organs of Hearing May Be Injured (p. 226, ^ 108).
" There are several things very commonly done which are extremely injurious to
the ear, and ought to be carefully avoided. And first, children's ears ought never
to be boxed. We have seen that the passage of the ear is closed by a thin mem-
brane, especially adapted to be influenced by every impulse of the air. If any
one designed to break the membrane, he could scarcely devise a more effective
means than to bring the hand suddenly down upon the outer ear, thus driving the
air violently before it, with no possibility for its escape but by the membrane
giving way. And far too often permanent deafness has thus been produced.
Three things should be remembered here: i. That slight degrees of deafness,
often lasting only for a time, are very common among children, especially during
or after colds. 2. That a slight deafness, which does not prevent a person from
hearing when he is expecting to be spoken to, will make him very dull to what he
is not expecting ; and 3. That there is a kind of deafness in which a person can
hear pretty well while listening, but is really very hard of hearing when not listen-
ing. All sorts of substances are sometimes put into the ear by children, who do
it to themselves or to each other in ignorant play. If every parent and teacher
warned his children against doing this, it would not be a useless precaution.
When the accident happens, the chief danger is that of undue haste and violence.
Such bodies should be removed by syringing with warm water alone, and no
attempt should be made to lay hold of them or move them in any other way.
Now, no cold fluid should ever enter the ear ; cold water is more or less irritating,
and if used for syringing rapidly produces extreme giddiness. Washing the ear
out with soap and water is bad. The use of any thing hard or stiff to clean out
the wax is improper. If there is any desire to do so, it shows that the ear is un-
healthy, and it wants soothing, not picking. Now and then an insect gets into
the ear and causes great pain : the way to get rid of it is to pour oil into the ear.
This suffocates the insect." Physiology for Practical Use.
THE VOICE.
CHAPTER XI.
THE VOICE.
Voice and SpeecJi The Larynx, or tfie Organ of the Voice Tlie Vbea\
Cards The Laryngoscope The Production of the Voice Tlie Use
of the Tongue The different Varieties of Voice The Change of
Voice Its Compass Purity of Tone Ventriloquy.
1. Voice and Speech. In common with the majority
of the nobler animals, man possesses the power of uttering
sounds, which are employed as a means of communication
and expression. In man, these sounds constitute the
voice ; in the animals, they are designated as the cry. The
song of the bird is a modification of its cry, which is ren-
dered possible from the fact that its respiratory function is
remarkably active. The sounds of the animals are gener-
ally, but not always, produced by means of their breathing
organs. Among the insects, they are sometimes produced
by the extremely rapid vibrations of the wings in the act
of flight, as in the case of the musquito ; or they are pro-
duced by the rubbing together of hard portions of the
external covering of the body, as in the cricket. Almost
all kinds of marine animals are voiceless. The tambour-
fish and a few others have, however, the power of making
a sort of noise in the water.
2. But man alone possesses the faculty of speech, or the
power to use articulate sounds in the expression of ideas,
and in the communication of mind with mind. Speech is
thus an evidence of the superior endowment of man, and
involves the culture of the intellect. An idiot, while he
1. The uttering of sounds by animals ? How produced ?
2. The evidence of man's superior endowment? What is stated of the idiot?
Parrot ? Raven ?
228 THE VOICE.
r
may have complete vocal organs and full power of uttering
sounds or cries, is entirely incapable of speech ; and, as a rule,
the excellence of the language of any people will be found
to be proportional to their development of brain. Man,
however, is not the only being that has the power to form
articulate sounds, for the parrot and the raven may also
be taught to speak by rote ; but man alone attaches mean-
ing to the words and phrases he employs.
3. Speech is intimately related to the sense of hearing,
A child born deaf is, of necessity, dumb also; not because
the organs of speech are imperfect, for he can utter cries
and may be taught to speak, and even to converse in a
rude and harsh kind of language; but because he can
form no accurate notion of sound. And a person, whose
hearing is not delicate, or as it is commonly expressed,
who "has no ear for music," cannot sing correctly. A per-
son who has impaired hearing commonly talks in an un-
naturally loud and monotonous voice. These examples
show the necessary relation of intelligence and the sense
of hearing with that form of articulate voice, which is
termed speech.
4. The Organ of the Voice. The essential organ
of the voice is the Larynx. This has been previously
alluded to in its relation to the function of respiration ;
and, in the chapter on that subject, are figured the front
view of that organ (Fig. 35), and its connection with the
trachea, tongue, and other neighboring parts (Fig. 38). It
is situated at the upper part of the neck, at the top of the
trachea, or tube by which air passes into and out of the
lungs. The framework of the larynx is composed of four
cartilages, which render it at once very strong and suffi-
ciently flexible to enable it to move according to the re-
quirements of the voice.
3. Speech and hearing? A deaf child? Person having "no ear for music?''
Impaired hearing ? What do the examples show?
4. Organ of the voice ? Where situated ? Of what is its framework composed ?
THE VOICE.
5. The names of the cartilages are (1) the thyroid,
which is a broad thin plate, bent in the middle and placed
in the central line of the front part, of the neck, where it
is known as thepomum Adami, or
Adam's apple (Fig. 55, B), and
where it may be felt moving up
and down with each act of swal-
lowing; (2) the cricoid, which is
shaped like a seal ring, with the
broad part placed posteriorly (Fig.
55, E). At the top of the cricoid
cartilage are situated the two small
arytenoid cartilages, the right one
of which is shown in Fig. 55, c.
These latter little organs are much
more movable than the other two,
and are very important in the pro-
duction of the voice. They have
a true ball and socket joint, and
several small muscles which con-
tract and relax with as perfect regu-
larity and accuracy as any of the
larger muscles of the body.
" 6. The interior of the larynx is SECTION OF T J H ^ RYNX AND
lined with a very sensitive mucous
membrane, which is much more
closely adherent to the parts be-
ntath than is usually the case with
membranes of this description. The epiglottis (A), con-
sisting of a single leaf-shaped piece of cartilage, is attached
to the front part of the larynx. It is elastic, easily moved,
and fits accurately over the entrance to the air-passages
below it. Its office is to guard these delicate passages and
the lungs against the intrusion of food and other foreign
FIG. 55.
^ ?jj 5
g,
|;
H ' The Trachea -
5. Names, formation, and situation of the cartilasres f
6. Lining of the interior of the larynx ? The epiglottis ?
230 THE VOICE.
articles, when the act of swallowing takes place. It also
assists in modifying the voice.
A 7. The Vocal Cords. Within the larynx, and stretched
r across it from the thyroid cartilage in front to the aryte-
noid cartilages behind, are placed the two sets of folds,
called the vocal cords. The upper of these, one on each
side, are the false cords, which are comparatively fixed and
inflexible. These are not at all essential to the formation
of vocal sou ads, for they have been injured, in those lower
animals whose larynx resembles that of man, without ma-
terially affecting their characteristic cries. Below these,
one on each side, are the true vocal cords (Fig. 55, F),
which pursue a similar direction to the false cords, namely,
from before backward. But they are composed of a highly
elastic, though strong tissue, and are covered with a thin,
tightly-fitting layer of mucous membrane. Their edges
are smooth and sharply defined, and when they meet, as
they do in the formation of sounds, they exactly match
each other.
8. Between the true and false vocal cords is a depression
on each side, which is termed the ventricle of the larynx
(Fig. 55, D). The integrity of these true cords, and their
free vibration, are essential to the formation of the tones
and the modulation of the natural voice. This is shown
by the fact that, if one or both of these cords are injured
or become diseased, voice and speech are compromised;
or when the mucous membrane covering them becomes
thickened, in consequence of a cold, the vocal sounds are
rendered husky and indistinct. "When an opening is made
in the throat below the cords, as not infrequently happens
in consequence of an attempt to commit suicide, voice is
impossible except when the opening is closed by external
pressure.
7. Where are the vocal cords ? The false cords ? The true cords?
8. Where IP the ventricle of the larynx ? The essentials to the formation of the
ty net? and modulation of the voice 1
THE VOICE. 231
9. The interval or space between the true cords of the
voice is constantly varying, not only when their vocal
function is in exercise, but also during the act of respira-
tion. Every time the lungs are inflated, the space
increases to make w r ide the entrance for the air; and dimin-
ishes slightly during expiration. So that these little cords
move gently to and fro in rhythm with the expansion and
contraction of the chest in breathing. These movements
and others may be seen to take place, if a small mirror
attached to a long handle be placed back into the upper
part of the throat; the handle near the mirror must be
FIG. 56.
A VIEW OF THE VOCAL CORDS BY MEANS op THE LARYNGOSCOPE.
bent at an angle of 45, se that we may look "around the
corner," so to speak, behind the tongue. The position
which the mirror must assume will be understood by
reference to Fig. 38. A view of what may be seen under
favorable circumstances, during tranquil inspiration is
represented in Fig. 56. The vocal cords are there shown as
narrow, white bands, on each side of the central opening,
and since the image is inverted, the epiglottis appears up-
permost. The rings partly seen through the opening be-
long to the trachea. This little mirror is the essential part
9. Variation in the interval between the true cords of the voice? Experiment
wtth tb<) mirror?
232 THE VOICE.
of an instrument, which is called the laryngoscope, and,
simple as it may seem, it is accounted one of the most val-
uable of the recently invented appliances of the medical
art.
10. The Production of the Voice. During ordi-
nary tranquil breathing no sound is produced in the lar-
ynx, true vocal tones being formed only during forcible
expiration, when, uy an effort of the will, the cords are
brought close together, and are stretched so as to be very
tense. The space between them is then reduced to a
narrow slit, at times not more than T J-g- of an inch in
width ; and the column of expired air being forced through
it causes the cords to vibrate rapidly, like the strings of a
musical instrument. Thus the voice is produced in its
many varieties of tone and pitch; its intensity, or loud-
ness, depending chiefly upon the power exerted in expell-
ing the air from the lungs. When the note is high, the
space is diminished both in length and width ; but when it
is low, the space is wider and longer (Fig. 57, B, c), and
the number of vibrations is fewer within the same period
of time.
FIG. 57.
THE DIFFERENT POSITIONS OF THE VOCAL CORDS.
A, The position during inspiration. B, In the formation of low notes.
C, In the formation of high notes.
11. The personal quality of the voice, or that which en-
ables us to recognize a person by his speech, is mainly due
to the peculiar shape of the throat, nose, and mouth, and
10. The formation of true vocal tones ?
1 1 . To what ie the personal quality of the voice mainly due ? What aids are
there ?
THE VOICE. 233
the resonance of the air contained within those cavities.
The walls of the chest and the trachea take part in the
resonance of the voice, the air within them vibrating at
the same time with the parts above them. This may be
tested by touching the throat or breast-bone, when a
strong vocal effort is made. The teeth and the lips also
are important, as is shown by the unnatural tones emitted
by a person who has lost the former, or by one who is
affected with the deformity known as "hare-lip." The
tongue is useful, but not indispensable to speech ; the case
of a woman is reported, from whom nearly the whole
tongue had been torn out, but who could, nevertheless,
speak distinctly and even sing.
12. The varieties of voice are said to be four in num-
ber ; two, the bass and tenor, belonging to the male sex ;
and two, the contralto or alto, and soprano, peculiar to the
female. The baritone voice is the name given to a variety
intervening between the bass and tenor. In man, the
voice is strong and grave; in woman, soft and high. In
infancy and early youth, the voice is the same in both
sexes, being of the soprano variety : that of boys is both
clear and loud, and being susceptible of considerable train-
ing, is highly prized in the choral services of the church
and cathedral. At about fourteen years of age the voice is
said to change ; that is, it becomes hoarse and unsteady by
reason of the rapid growth of the larynx. In the case of
the girl, the change is not very marked, except that the
voice becomes stronger and has a wider compass ; but in
the boy, the larynx nearly doubles its size in a single year,
the vocal cords grow thicker, longer, and coarser, and the
voice becomes masculine in character. During the prog-
ress of this change, the use of the voice in singing is inju-
dicious.
13. The ordinary range of each of the four varieties of
12. Varieties of voice ? The baritone ? The voice in early youth ?
1 3 ^ The range of the voice ? Jleeult of careful training of the vocal organs ?
234 THE VOICE.
the voice is about two octaves; but this is exceeded in the
case of several celebrated vocalists. Madame Parepa-Rosa
has a compass of three full octaves. When the vocal or-
gans have been subjected to careful training, and are
brought under complete control of the will, the tension
of the cords become exact, and their vibrations become
exceedingly precise and true. Under these circumstances
the voice is said to possess "purity" of tone, and can be
heard at a great distance, and above a multitude of other
sounds. The power of a pure voice to make itself heard
was recently exemplified in a striking manner : at a musi-
cal festival held in an audience-room of extraordinary size,
and amid an orchestra of a thousand instruments and a
chorus of twelve thousand voices, the artist named above
also sang ; yet such was the purity and strength of her
voice that its notes could be clearly heard rising above the
vast waves of sound produced by the full accompaniment
of chorus and orchestra.
14. In the production of the articulate sounds of speech,
the larynx is not directly concerned, but those sounds
really depend upon alterations in the shape of the air-
passages above that organ. That speech is not necessarily
due to the action of the larynx is proven by the following
simple experiment. Let an elastic tube be passed through
the nostril to the back of the mouth. Then, while the
breath is held, cause the tongue, teeth, and lips to go
through the form of pronouncing words, and at the same
time, let a second person blow through the tube into the
mouth. Speech, pure and simple, or, in other words, a
whisper is produced. Still further continue the experi-
ment, while permitting vocal sounds to be made, and there
will be produced a loud and whispering speech at the same
moment ; thus showing that voice and speech are the re-
sult of two distinct acts. Sighing, in like manner, is pro-
14. The production of the articulate sounds ? What experiment is mentioned ?
THE VOICE. 235
duced in the mouth and throat ; if, however, a vocal sound
be added, the sigh is changed into a groan.
15. Ventriloquism is a peculiar modification of natu-
ral speech, which consists in so managing the voice that
words and sounds appear to issue, not from the person,
but from some distant place, as from the chimney, cellar,
or the interior of a chest. The original meaning of the
word ventriloquism (that is, speaking from the belly), in-
dicates the early belief that this mode of speech was de-
pendent upon the possession and use of some special organ
besides the larynx and mouth ; but at the present time, it
is known that it is produced by these organs alone, and
that the sources of deception consist on the part of the
performer, in the dexterous management of the voice, to-
gether with a talent for mimicry ; and, on the part of the
auditory, in the liability of the sense of hearing to error in
respect to the direction of sounds. The ventriloquist not
only seems to " throw his voice," as it is said, or simulates
the sound as it usually appears at a distance with but lit-
tle motion of the lips and face, but he imitates the voices
of an infant and of a feeble old man, of a drunken man
disputing with an exasperated wife, the broken language of
a foreigner, the cry of an animal in distress, demonstrating
that the performer must be proficient in the art of mimicry.
Ventriloquism was known to the ancient Eomans and
Greeks; and it is thought that the mysterious responses
that were said to issue from the sacred trees and shrines
of the oracles at Dodona and Delphi, were really uttered
by priests who had the power of producing this form of
speech.
1 5. What is ventriloquism ? Indication of the original meaning of the word ?
ilow are the ventriloquous t-ounds produced ?
NOTES.
1. Voice in Man and Animals (p. 228, 1 2.) The human voice, taking
male and female together, has a range of nearly four octaves. Man's power of
speech, or the utterance of articulate sounds, is due to his intellectual develop-
ment more than to any great structural difference between him and the Apes.
Song is produced in the glottis, speech by the mouth. The parrot and mocking-
bird use the tongue in imitating human sounds. Orion's Zoology.
2. Certain Peculiarities of the Voice (p. 228, \ 3.)" Voice is a sound
produced in the throat by the passage of the air through the glottis, as it is ex-
pelled from the lungs. It is grave and strong in man, soft and higher in women ;
it varies according to age. It is alike in both sexes in infancy, but is modified in
youth ; then the voice is said to l change.' In the young woman it descends a
note or two, and becomes stronger. In the young man the change is much more
strongly marked. At the fourteenth or fifteenth year the voice loses its regularity,
becomes harsh and unequal, the high notes cannot be sounded, while the grave
ones make their appearance. A year is generally sufficient for this change to be
complete, and the voice of the child gives place to that of the man. Exercise of
the voice in singing should be very moderate, if not entirely suspended, while this
change is going on. Voice is divided into singing and speaking voice. One dif-
fers from the other almost as much as noises do from musical sounds. It is the
short duration of speaking sounds which distinguishes them from those of singing.
This is proved by the fact that if we prolong the intonation of a syllable, or utter
it like a note, the musical sound becomes evident. And if we pronounce all the
syllables of a phrase in the same tone, the speaking voice closely resembles psalm-
singing. Every one must have noticed this in hearing school-boys recite or read
in a monotone, and the analogy is complete when the last two or three syllables
are pronounced in a different tone. Spoken voice is moreover always a chant
more or less marked, according to the individual and the sentiment expressed.
The accentuation peculiar to certain languages also gives the speech the character
of a chant : to a French ear an Italian preacher seems always to sing. A chant
also is caused by those inflexions of the voice, which express our emotions and
our passions. They extend from the feeble murmur, which the ear scarcely per-
ceives, to the piercing cry of pain. Affectionate, sympathetic, imperious, or
hostile, they sometimes charm, sometimes irritate, and always move us. It is
related of Gretry, that he amused himself by noting as exactly as possible the
1 Bonjour, monsieur ! ' of the persons who visited him ; and these words expressed
by their intonation, in fact, the inpst opposite sentiments, although literally the
same. Baron, the comedian, moved his audience to tears by his recitation of the
stanzas of the song, ' Si le roi nfa-vait donne Paris sa granc? ville ' If the king
had given me Paris his great city." Le Pileur on Wonders of the Human Body.
3. The Benefits of Vocal Exercise (p. 234, 1" 13) " Reading aloud and
recitation are more useful and invigorating musical exercises than is generally
imagined, at least when managed with due regard to the natural powers of the
individual, so as to avoid effort and fatigue. Both require the varied activity of
most of the muscles of the trunk to a degree of which few are conscious, till their
attention is turned to it. In forming and undulating the voice, not only the chest
but also the diaphragm and abdominal muscles are in constant action, and com-
municate to the stomach and bowels a healthy and agreeable stimulus ; and conse-
quently, where the voice is raised and elocution rapid, as in many kinds of public
speaking, the muscular effort comes to be even more fatiguing than the mental.
When care is taken, however, not to carry reading aloud so far at one time as to
excite the least sensation of soreness or fatigue in the chest, and it is duly repeated,
it is extremely useful in developing and giving tone to the organs of respiration,
NOTES.
and to the general system. To the invigorating effects of this kind of exercise,
the celebrated Cuvier was hi the habit of ascribing his own exemption from con-
sumption, to which, at the time of his appointment to a professorship, it was be-
lieved he would otherwise have fallen a sacrifice. The exercise of lecturing
gradually strengthened his lungs and improved his health so much that he was
never afterwards threatened with any serious pulmonary disease. But of course
this happy result followed because the exertion of lecturing was not too great for
the then existing condition of his lungs. 7 ' Combos Physiology.
4. Improvement of Conversation by Vocal Training (p. 235, \ 14.)
u For years I had fallen into a low, drawling, lazy tone of voice in my ordinary
conversation ; my utterance came lorth in a cloud, and had its dwelling there.
From divers experiments and observations I had long ago assured myself that this
was a capital defect; but this assurance had brought with it no reform. Now, at
last, I attempted it in good earnest. I studied to bring myself out of my listlessness,
to acquire a rapid, distinct and articulate enunciation. No man can miss this acqui-
sition unless from some organic infirmity, provided only that he pursue it steadily
and earnestly. I employed a variety of exercises for the voice, as recitation, the
frequent repetition of the same passage, slowly at first, and then more quickly up
to my highest pitch of rapidity, the pronunciation of foreign languages, Greek for
the sake of fullness, and French for distinctness and despatch. As a result, I be-
came comparatively a clear and satisfactory speaker ; and as my talk was more
distinct my thoughts were all the more pointed and precise. I acquired an even-
ness of tone, a confidence, a complacency ; my conversation, as the French say
of their language, went of itself; I had leisure to look chiefly to my direction, to
march on to my object." Self -Formation, by Capel Lofft.
5. Ventriloquism and Sound-painting (p. 235, 1 15.) u Ventrilo-
quism bears the same relation to other phenomena of sound that perspective does
to optical phenomena. The art of perspective consists in portraying upon a flat
surface the appearance of objects at a distance from it, so that the same effect shall
be produced upon the eye by the picture as would be produced by the objects
themselves. In order to do this, the form, tints, and shades are reproduced, not as
they really are, but as they are modified by position and distance. Or it may be
said to consist in making and arranging a group of objects so that when viewed at
a given distance they shall produce the same optical effect produced by another
set of objects arranged in different positions and at different distances.
u Ventriloquism consists in making and arranging sounds so that when heard
at a given distance, they shall produce the same effect upon the ear that anothe/
set of sounds produce arranged in different positions and at different distances.
u Sounds from a distance are of course weakened, and they also have another
quality which may be compared to the indistinctness or outline in objects seen at a
distance. In proportion as the fine ear of the ventriloquist can appreciate these
modifications will be his success in imitating distant sounds. For as to see cor-
rectly is the first essential to success in drawing, so is hearing correctly the first
essential in ventriloquism.
" There are many sounds which cannot be imitated by voice merely, such as
the singing of birds, the strident noise of a saw, the whistling of a plane, etc.
Such and similar unmusical sounds are imitated by means of the teeth, the lips, or
the soft parts of the mouth. Thus the noise of a saw is like that produced by
hawking, only much prolonged, and modified by the cheeks ; singing of birds may-
be imitated by whistling through the teeth. The foaming of soda-water by breath-
ing with open lips into a tumbler, etc. To persons having a fine ear this amusing
art is not difficult, but we object to the name applied to it. It ought to be called
sound-painting"
23G THE MICROSCOPE.
CHAPTER XII.
THE USE OF THE MICROSCOPE IK THE STUDY OF
PHYSIOLOGY.
1. The Law of the Tissues. The will of an infinite
Creator is obeyed by atoms as well as by worlds. He has
seen fit to commit all the functions of life to structures or
tissues so small as to be invisible to the naked eye. A
muscle, for example, as we have already learned, is com-
posed of innumerable filaments, visible only by the aid of
the microscope; and the power of the muscular mass is
but the. sum of the contractile power of the filaments
which enter into its composition. Again, each cell of the
liver, invisible to unassisted sight, is a secreting organ, and
the liver performs as much duty as the sum of these mi-
nute organs renders possible and no more.
2. The Necessity of the Microscope. If, there,
fore, we would know the real structure of the human
body, we must make use of the microscope. We are not at
liberty either to use it or not ; we must have recourse to it
in order to obtain a real knowledge of the human body,
Our eyes are constructed for the common offices of life, to.
provide for our wants and guard us from the ordinary
sources of danger ; but by arming them with lenses, the
real structure of plants and animals is revealed to our
intelligence ; and enemies, otherwise invisible, that lie in
wait in the air we breathe, and in our daily food and drink,
to destroy life, are guarded against.
3. Convex lenses, or magnifying glasses, are disks
of glass or other transparent substance, which have the
1 . The will of the Creator, by what obeyed ? The power of a muscle ?
Amount of duty performed by the liver ?
2. Necessity for using the microscope ? The advantages gained by its use ?
3. What are convex lenses? Kind of lenses used in microscopes? Experi-
ment ? Picture thrown upon the eye ? Derivation of the word microscope ':
THE MICROSCOPE. 237
property of picturing upon the retina of the eye an
image of an object larger than the image produced there
without their aid. The glasses used in microscopes are
either double convex lenses (a) or plano-convex lenses ().
b
If a double convex lens or a plano-convex one be placed
over a hole in the shutter of a darkened room, or over
the key-hole of a door, and a piece of paper be held at a
proper distance, a picture of all objects in front of the
lens will be thrown on the paper, as in the camera-obscura
or the magic-lantern. Now, in the same manner, a lens
throws a picture of objects to which it is directed on the
retina of the eye, and when that picture is larger than the
image made in the eye by the object, without the aid of
the lens, it is magnified, or the lens has served as a micro-
scope, so called, from its use in seeing small objects, from
milcros, small, and skopeo, to see.
4. Different Kinds of Microscopes. Microscopes
are either simple or compound. The glasses of magnifying
spectacles, like those commonly used by aged persons, are
simple microscopes. Magnifying glasses, mounted in
frames such as are for sale by opticians and others, for
the detection of counterfeit money, are simple microscopes,
and are useful in studying the coarser structure of plants
and animals.
5. The most powerful simple microscopes are made by
melting in a flame a thread of spun glass, so as to form a
4. Kinds of microscope ? What are simple microscopes ?
5. Construction of the most powerful simple microscopes? In practice? A
doublet ? Triplet ? Why are compound microscopes superior to simple ones ?
238 THE MICROSCOPE.
minute globule or bead, which, when set in a piece of
metal and used to examine objects on a plate of glass held
up to the light, gives a high magnifying power. In prac-
tice, however, it is found better to use several magnifying
glasses of moderate power, than a simple lens alone of
high power. A combination of two lenses is called a doub-
let of three, a triplet. All simple microscopes throw an
enlarged image of the object upon the retina. Compound
microscopes are so constructed that the enlarged image of
an object is again magnified by a second lens, and hence
their magnifying power is vastly superior to that of simple
microscopes.
6. The accompanying diagrams will explain the action
of the compound microscope compared with that of the
6'
FIG. 58. SIMPLE MICROSCOPE.
simple microscope. In Fig. 58, which represents the work-
ing of the simple microscope, the rays from the object (a b),
passing through the lens (L), form an image (a' b') in the
retina of the eye (E), and as all images are inverted in the
eye, the object is seen as all other objects are, and appears
erect. In Fig. 59 is seen the action of the compound
microscope. An inverted image (a' b') of the object (a b)
is magnified by the second lens (L'), and an erect image is
thrown upon the retina, which, as ail other objects seen
erect with the naked eye are inverted, gives to the image
a contrary direction, or inverts it to the mind.
0. Explain, by means of the diagram, the action of the compound microscope.
THE MICROSCOPE.
239
7. A Compound Microscope consists of two por-
tions : the optical portion, or the lenses, and the mechanical
portion, or the instrument which bears
J. *-W^ 7 PK M
the lenses. The glasses of a compound
microscope are two : the object-glass (D),
Fig. 60, and the lower lens of Fig. 59,
and the ocular or eye-piece (A), Fig. 60,
and the upper piece of Fig. 59. Both
the object-glass and the eye-piece may,
and usually do, consist of more than
one lens, for, as previously mentioned,
better results are obtained by a com-
bination of lenses of moderate power
than by single lenses of high power
and great curvature.
8. How to choose and use a
Microscope. No attractiveness in
the mechanical part of a microscope
can compensate for inferior lenses;
and the very first consideration in the
choice of an instrument should be the
excellence of the optical part of the
instrument. In the use of the instru-
ment, care should be exercised to keep
the lenses clean, free from dust, not to
press the object-glass upon the object
under observation, and not to wet it
in the water in which most objects are
examined. A good microscope re-
quires its own table ; and when not
in use, should be covered by a bell
glass or a clean linen cloth.
9. The mechanical portion of the instrument varies
FIG. 59.
COMPOUND MICROSCOPE:.
7 Portions, in a compound microscope ? The glasses ?
8. How to choose a microscope ? How to use it?
f). The characteristics of the best instrument ? What special requisites ehcul'.i
be insisted uoon ? Why, as to a horizontal stage ?
240
THE MICROSCOPE.
greatly in different instruments. That one is the best
which is simplest, the most solid and easily managed.
The stage (E), upon which the object is placed, should
A, Eye-piece.
B, Body.
C, Collar.
D, Object-glass.
FIG. 60.
E, Stage.
F, Hinge.
G, Mirror.
H, Stand.
not be movable : it should be solid and firm. The
screw by which the focal distance is adjusted, and which
THE MICROSCOPE.
241
*s in constant use, should be so placed that it can be
worked by the hand resting on the table: otherwise fa-
PlG. 61.
tigue is soon induced. The direction of the tube carry
242 THE MICROSCOPE.
ing the glasses should be perpendicular, and the stage
therefore horizontal. Most objects in human anatomy are
examined in water or in other liquids, or they are them-
selves liquids; hence an oblique stage is often incon-
venient.
10. Additional Apparatus. As almost all objects
in human anatomy are examined by transmitted light
thrown up from the mirror (G, Fig. 60) beneath the stage
through the object to the eye, they must be placed upon
strips of clear glass about three inches long and one inch
wide, commonly called "slides." These should be pro-
cured with the microscope. Again, most objects seen with
high powers require to be covered with a thin plate of
glass, very properly called a " cover," that the moisture of
the specimen may not tarnish the object-glass. Square or
circular covers of very thin glass are therefore provided ;
and a good supply of these should be always on hand.
These glasses should be kept in a covered dish filled with
a mixture of alcohol and water. Simple water will not re-
move the fatty matter which exists in all animal tissues,
and, therefore, the glasses cannot be thoroughly cleaned
with it alone.
11. When glasses are required for use, they should be
removed from the liquid and wiped clean and dry with a
soft linen handkerchief. Delicate knives, scissors, needles
mounted in handles, forceps, pipettes or little tubes for
taking up water, should be obtained ; these are essential to
all microscopical study. The table should be supplied with
glass-stoppered bottles containing the various liquids or-
dinarily used in the study of physiology. Thus, tincture
of iodine is indispensable in studying vegetable structure,
acetic acid in the study of animal tissues ; and other articles
will have to be added from time to time, as your progress
in study demands them.
10. Slides? Covers, square and circular ? How kept?
11. Cleaning the glares'? Knives, eeispon*, etc. ? Various liqtiidi*?
THE MICROSCOPE. 243
12. Preliminary Studies. In order to prepare the
way for the study of any department of science with the
aid of the microscope for the microscope is but an eye, and
can be turned in almost any direction for purposes of in-
vestigation it is necessary to become acquainted with the
many objects which are liable to complicate the examina-
tion of particular structures. Both air and water are full
of floating bodies, and the most common of these should
first occupy the attention. In the city, particles of starch
are always floating in the air. Take a very minute portion
of wheat flour, place it in the middle of a clean glass " slide,"
drop upon it a drop of pure water, cover it with a plate
of thin glass, and examine it with a, power of from one
hundred to six hundred diameters. It will be found to be
composed of minute grains or granules, the largest of which
are made up of coats or layers, like an onion, arranged
around a central spot called the hilum.
13. Make another preparation in the same manner, and,
after adding the water and before covering with the thin
glass cover, add a small drop of a solution of iodine.
Now, upon examining the specimen, every grain will be
seen to be of a beautiful deep blue color. After thus
studying wheat starch, the starch of Indian corn, of arrow-
root, and of various grains should be examined in like man-
ner, and their resemblances and differences noted. The
granules of potato-starch are as distinctly marked as any.
(See Fig. 15, page 61.)
14. Fibres of cotton, lint, and wool are liable to be
found in every specimen prepared for microscopical exami-
nation. In order to study these, any cotton, woollen, or
linen fabric, or garment, may be scraped, and the scrap-
ings placed on a piece of glass moistened with water, cov-
ered with the thin glass plate or cover as before, and exam-
1 2. Bodies, in air and water ? The examination of starch ?
13. The examination with solution of iodine ? Advice respecting other arti-
cles ?
14. Directions for examining cotton and other fibres ? Vegetable hairs?
244 THE MICROSCOPE.
ined with the same magnifying power, namely, from one
hundred to six hundred diameters. Vegetable hairs or
down are constantly floating in air and water. These are
of very various forms, are simple or grouped, and form
very interesting objects of study. They are readily pro-
cured from the epidermis or outer membrane of the leaves
or stems of plants, by section with a delicate knife.
15. The tissues of plants, epidermis, ducts, and woody
fibres are constantly found in microscopic preparations.
They may be studied in delicate sections made with
a sharp knife, or by tearing vegetable tissues apart with
needles. The down of moths, the hairs of different,
animals, the fibres of paper, the most common animal-
cules in water, the dust of shelves, and generally the
structures found in all vegetable and animal substances
by which we are surrounded, should be studied as a pre-
liminary to any special line of microscopical investiga-
tion.
16. The Study of Human Tissues. When this has
been done and familiarity with the use of the instrument
has been obtained, proceed to the study of the human
body, for human physiology is our subject. If the end of
the finger be pricked with a pin, a drop of blood may be
procured for examination. Place this on one of the glass
slides, cover it with a thin piece of glass, press down the
cover so as to make a thin layer, and then examine with
the magnifying power just mentioned. Do not add water,
for that will cause the blood corpuscles to disappear. If
the drop of blood is placed under the microscope at once
after being drawn from the finger, most interesting phe-
nomena will be observed. The red corpuscles will be seen
to arrange themselves in rows, like piles of coin, while the
blood is coagulating. The spherical, white corpuscles will
15. Directions for examining various tissues? Down of moths, and other
structures ?
1 6. Directions for examining a drop of blood ?
THE MICROSCOPE. 245
be left out of the rows of red disks, and, if the highest
power be used, will be seen to change their shape con-
stantly.
17. If you scrape with a dull knife the inside of the
cheek, the flattened scales of " pavement epithelium," or
of the insensible covering which, analogous to the scarf-
skin on the outer surface of the body, lines the cavities of
its interior, may be readily studied. They have the appear-
ance of transparent tiles, each enclosing a round or oval
body, called its nucleus. Dandruff and the scrapings
from the skin of the body are , composed of scales like
those of the mouth, but they differ somewhat in being
hardened by horny matter, and in having a very faint
central body or nucleus.
18. The Tissues of the Inferior Animals. The
warm-blooded animals do not differ in the tissues, or mi-
croscopic structures, that compose them, but only in the
amount and arrangement of these tissues. Milne Edwards
says these tissues " do not differ much in different animals,
but their mode of association varies ; and it is chiefly by
reason of the differences in the combination of these asso-
ciations in various degrees, that each species possesses the
anatomical properties and characters which are peculiar
to it."
19. Hence the butcher's stall will furnish all the mate-
rials for the study of the microscopic tissues. The struc-
ture of the heart, lungs, liver, brain, and muscle may all
be studied, and well studied, by using minute pieces of
the flesh of the lower animals, especially of the quadru-
peds. Such portions of these animals as are not exposed
for sale can be readily obtained by order from the slaugh-
ter-house. To examine with the powers of which we
have been speaking, it is only necessary to cut off exceed-
1 7. Examination of the scales of the mouth ? Dandruff?
18. In what, as respects the tissues, do the warm blooded animals
Statement of Milne Edwards ?
^ 19. How to procure materials for the study of the tissues of man ?
THE MICROSCOPE.
ingly small pieces, tear them apart with needles, or make
very delicate sections with a sharp knife.
20. Incentives to Study. A complete knowledge of
all minute structures is not to be expected at once, for you
are here introduced into a new realm of Nature, a world
of little things as vast, as wonderful, and as carefully con-
structed as the starry firmament, that other realm of
grand objects which the astronomer nightly scans with the
telescope. It will not appear singular, therefore, if, at first,
you feel strange and awkward in this new creation. With a
little perseverance, however, and with the attention directed
toward simple objects at the outset, it will not be long be-
fore an increasing experience will engender confidence.
21. If to all this there be added an enthusiastic study of
the standard authorities on the subject, the rate of progress
will be by so much the more rapid. As compared with
similar studies, few possess more interest than microscopy,
and to the one who pursues it with fondness, it constantly
affords sources of pleasure and agreeable surprises ; : and in
the end, often leads to new and valuable additions to the
sum of human knowledge. The depths which the micro-
scope is employed to fathom are no more completely known,
than are the heights above us explored and comprehended
by the astronomer.
QUESTIONS FOR TOPICAL REVIEW.
State what you can on the following subjects :
1. Voice and speech 227, 228
2. The organ of the voice 228, 229
3. The vocal cords 230, 231
4. The production of the voice.232 233
5. The varieties of voice 233, 234
6. Ventriloquism 235
7. The law of the tissues 236
8. Necessity of the microscope
9. Convex fenses ...2
236
.23K, 237
10. Kinds of microscope 237, 238
11. Choosing a microscope 239, 242
12. Preliminary studies 243, 244
13. The study of human tissues 244
14. The study of the inferior animals 215
APPENDIX.
POISONS AND THEIR ANTIDOTES.
ACCIDENTS from poisoning are of such frequent occurrence, that
every one should be able to administer the more common antidotes,
until the services of a physician can be obtained. As many poiMSM
bear a close resemblance to articles in common use, no dangerous
substance should be brought into the household without having the
word poison plainly written or printed on the label ; and any pack-
age, box, or rial, without a label, should be at once destroyed, if the
contents are not positively known.
When a healthy person is taken severely and suddenly ill toog,
after some substance Jias been swallowed, we may suspect that he has
been poisoned. In all cases where poison has been taken into the
stomach, it should be quickly and thoroughly evacuated by some
active emetic, which can be speedily obtained This may be accom-
plished by drinking a tumblerful of warm water, containing either a
tablespoonful of powdered mustard or of common salt, or two tea-
spoonfuls of powdered alum in two tablespoonfuls of syrup. When
vomiting has already taken place, it should be maintained by copious
draughts of warm water or mucilaginous drinks, such as gum-water
or flaxseed tpa, and tickling the throat with the finger until there ip
reason to believe that all the poisonous substance has been expelled
from the stomach.
The following list embraces only the more common poisons, to
gether with such antidotes as are usually at hand, to be used until
the physician arrives.
POISONS.
Acids. Hydrochloric acid; muriatic acid (spirits of salt); nitric
acid (aqua fortis) ; sulphuric acid (oil of vitriol).
ANTIDOTE. An antidote should be given at once to neutralize the
acid. Strong soapsuds is an efficient remedy, and can always be
obtained. It should be followed by copious draughts of warm water
or flaxseed tea. CLalk, magnesia, soda or saleratu (with waterl of
248 APPENDIX.
lime-water, are the best remedies. When sulphuric acid has been
taken, water should be given sparingly, because, when water unites
with this acid, intense heat is produced.
Oxalic acid.
ANTIDOTE. Oxalic acid resembles Epsom salts in appearance, and
may easily be mistaken for it The antidotes are magnesia, or chalk
mixed with water.
Prussia Acid; oil of Utter almonds ; laurel water; cyanide of pot as-
a ium (used in electrotyping).
ANTIDOTE. OoLl douche to the spine. Chlorine water, or water
of ammonia largely diluted, should be given, and the vapor arising
from tuem may be inhaled.
Alkalies and their Salts. AMMONIA (hartshorn), liquor or water
of 'ammonia. I'GTASSA.: caustic potash, strong ley, carbonate of potassa
ipearlash), iterate of potassa (saltpetre).
ANTIDOTE. Give the vegetable acids diluted, as weak vinegar ,
acetic, citric, 01 tartaric acids dissolved in water. Castor oil, linseed oil,
and sweet oil luay also be used ; they form soaps when mixed with the
free alkalies, w^ich they thus render harmless. The poisonous effects
of saltpetre mast be counteracted by taking mucilaginous drinks
freely, so as to produce vomiting.
Alcohol.. Brandy, wine ; all spirituous liquors.
ANTIDOTE. Give as an emetic ground mustard or tartar emetic. Lf
the patient cannot swallow, introduce a stomach pump; pour cold
water on the head.
Oases. Chlorine, carbonic acid gas, carbonic oxide, fumes of burning
fhaicoal, sulphuretted hydrogen, illuminating or coal-gas.
ANTIDOTE. For poisoning by chlorine, inhale, cautiously-, ammonia
(hartshorn). For the other gases, cold water should be poured upon
the head, and stimulants cautiously administered ; artificial icspira-
tion. (See Marshall Halts Ready Method, page 250.)
Metals. Antimony, tartar emetic, wine of antimony, etc.
ANTIDOTE. If vomiting has not occurred, it should be produced by
tickling the throat with the finger or a feather, and the abundant use
of warm water. Astringent infusions, such as common tea, oak bark,
and solution of tannin, act as antidotes.
Arsenic. White arsenic, Fowler's solution, fly -powder, cobalt, Pari*
green, etc.
ANTIDOTE. Produce vomiting at once with a tablespoon/ill or two
of powdered mustard in a glass of warm water, or with ipecac. The
antidote is hydrated peroxide of iron. If Fowler's solution has been
taken, lime-water must be given.
A.PPENDIX.
Copper. Acetate of copper (verdigris), sulpluite of copper (blue
vitriol), food cooked in dirty copper vessels, or pickles made green
by copper.
ANTIDOTE. Milk or white of eggs, with mucilaginous drinks (flax
seed tea, etc.), should be freely given.
Iron. SulpJuite of iron (copperas), etc.
ANTIDOTE. Carbonate of soda in some, mucilaginous drink, or in
water, is an excellent antidote.
Lead. Acetate of leid (sugar of lead;, carbonate of lead (white
icad), water kept hi Deaden pipes or vessels, food cooked in vessels
glazed with lead.
ANTIDOTE. Induce vomiting with ground mustard or common
salt in warm water. The antidote for soluble preparations of lead is
Epsom salts; for the insoluble forms, sulphuric acid largely diluted
Mercury. Bichloride of mercury (corrosive sublimate), ammoniated
mercury (white precipitate), red oxide of mercury (red precipitate), red
mlphuret of mercury (vermilion).
ANTIDOTE. The white of eggs, or wheat flour beaten up with
water and milk, are the best antidotes.
Silver. Nitrate of silver (lunar caustic).
ANTIDOTE. Give a teaspoonful of common salt in a tumbler of
water. It decomposes the salts of silver and destroys their activity.
Zinc, SulpJuite uf zinc, etc. (white vitriol).
ANTIDOTE. The vomiting may be relieved by copious draughts
of warm water. The antidote is carbonate of soda administered in
water.
Narcotic Poisons. Opium (laudanum, paregoric, salts of mor-
phia, Godfrey's cordial, Dalby's carminative, soothing syrup, cholera
mixtures), aconite, belladonna, hemlock, stramonium, digitalis, tobacco,
kyosciamus, nux wmica, strychnine.
ANTIDOTE. Evacuate the stomach by the most active emetics, as
mustard, alum, or sulphate of zinc. The patient should be kept in
motion, and cold water dashed on the head and shoulders. Strong
coffee must be given. The physician will use the stomach pump and
electricity. In poisoning by nux vomica or strychnine, etc., chloro-
form or ether should be inhaled to quiet the spasms.
Irritant Vegetable Poisons. Croton til, oil of savine, poke, oil of
tansy, etc.
ANTIDOTE If vomiting has taken place, it may be rendered easier
by copious draughts of warm water. But if symptoms of insensibility
have come on without vomiting, it ought to be immediately excited b>
round mustard mixed with warm water, or some other active ernet V
250 APPENDIX.
and after its operation an active purgative should be given. Aftei
evacuating as much of the poison as possible, strong coffee or vinegar
and water may be given with advantage.
Poisonous Fish. Conger eel, mussels, crabs, etc.
ANTIDOTE. Evacuate, as soon as possible, the contents of the stom-
ach and bowels by emetics (ground mustard mixed with warm water
or powdered alum), and castor oil, drinking freely at the same time
of vinegar and water. Ether, with a few drops of laudanum mixer,
with sugar and water, may afterward be taken freely.
Poisonous Serpents. ANTIDOTE. A ligature or handkerchief
should be applied moderately tight above the bite, and a cupping-glass
over the wound. The patient should drink freely of alcoholic stim
ulants containing a small quantity of ammonia. The physician may
inject ammonia into the veins.
Poisonous Insects. Stings of scorpion, hornet, wasp, bee, etc.
ANTIDOTE. A piece of rag moistened with a solution of carbolic
acid may be kept on the affected part until the pain is relieved ; and
a few drops of carbolic acid may be given frequently in a little
water. The sting may be removed by making strong pressure
around it with the barrt. ^f a small watch-key.
DROWNING.
MARSHALL HALL'S " READY METHOD" of treatment in asphyxia
from drowning, chloroform, coal gas, etc.
1st. Treat the patient instantly on the spot, in the open air, freely
exposing the face, neck, and chest to the breeze, except in severe
weather.
2d. In order to clear the throat, place the patient gently on the face,
with one wrist under the forehead, that all fluid, and the tongue itself,
may fall forward, and leave the entrance into the windpipe free.
3d. To excite respiration, turn the patient slightly on his side, and
apply some irritating or stimulating agent to the nostrils, as ver<i
trine, dilute ammonia, etc.
4th. Make the face warm by brisk friction ; then dash cold water
upon it
5th. If not successful, lose no time; but, to imitate respiration,
place the patient on his face, and turn the body gently, but completely
<m tfo side, and a little beyond; then again on the face, and so on, al
ternately. Repeat these movements deliberately and perseveringly
APPENDIX. 251
fifteen times only in a minute. (When the patient lies on the thorax,
this cavity is compressed by the weight of the body, and aspiration
takes place. When he is turned on the side, this pressure is removed,
and inspiration occurs.)
6th. When the prone position is resumed, make a uniform and
efficient pressure along the spine, removing the pressure immediately,
before rotation on the side. (The pressure augments the expiration
the rotation commences t/ispiration.) Continue these measures.
7th. Rub the limbs upward, with firm pressure and with energy.
(The object being to aid the return of venous blood to the heart.)
8th. Substitute for the patient's wet clothing, if possible, such
other covering as can be instantly procured, each bystander sup-
plying a coat or cloak, etc. Meantime, and from time to time, to
excite inspiration, let the surface of the body be slapped briskly with
the hand.
9th. Rub the body briskly till it is dry and warm, then dash wld
water upon it, and repeat the rubbing.
Avoid the immediate removal of the patient, as it involves a
dangerous loss of time also, the use of bellows, or any forcing instru-
ment ; also, the warm bath, and all rough treatment.
GLOSSARY.
A.B-DO'MEN (Latin abdo, to conceal). The largest cavity ol the bouy
containing the liver, stomach, intestines, etc.; the belly.
A B-SOR' BENTS (L. ab and sorbeo, to suck up). The vessels which take
part in the process of absorption.
AB-SORP'TION. The process of sucking up fluids by means of an
animal membrane.
AC-COM-MO-DA'TION of the Eye. The alteration in the shape of the
crystalline lens, which accommodates or adjusts the eye for near
and remote vision.
AC'ID, LACTIC (L. lac, milk). The acid ingredient of sour milk ; the
gastric juice also contains it.
AL-BU'MKN, or Albumin (L. albus, white). An animal substance re-
sembling white of egg.
AL-BU'MI-NOSE (from airmen). A soluble animal substance pro-
duced in the stomach by the digestion of the albuminoid sub-
stances.
iL-BU'Mm-orD substances. A class of proximate principles resembling
albumen ; they may be derived from either the animal or vegetable
kingdoms.
A.I/I-MENT (L. alo, to nourish). That which affords nourishment;
food.
A.L-I-MENT'A-RY CA-NAL (from aliment). A long tube in which the
food is digested, or prepared for reception into the system.
AN-^ES-THET'ICS (Greek, av, an, without, or/tfSytfm, ai&thexia, feel
ing). Those medicinal agents which prevent the feeling of pain,
such as chloroform, laughing-gas, etc.
AN-I-MAL'CULE (L, animal' culum, a small animal). Applied to an
imals which can only be seen with the aid of the microscope. Ani-
malculum (plural, animalcula) is used with the same meaning.
A-OR'TA (Gr. dopreouaiy aorteomai, to be lifted up). The largest
artery of the body, and main trunk of all the arteries. It arises from
the left ventricle of the heart. The name was first applied to the
two large branches of the trachea, which appear to be lifted up by
the heart
GLOSSARY.
A/QUE-OUS HUMOR (L. aqua, water). A few drops of watery color-
less fluid occupying the space between the cornea and crystalline
lens.
A.-RACH'NOID MEM'BRANE (Gr. dpaxn?, arachne, a cobweb, and
e/doS, eidos, like). An extremely thin covering of the brain and
spinal cord. It lies between the dura mater and the pia mater.
A.R'BOR VI'T^B (L.). Literally, "the tree of life;" a name giveu to the
peculiar appearance presented by a section of the cerebellum.
AR'TER-Y (Gr. dt?p, aer, air, and rijpetv, terein, to contain). A
vessel by which blood is conveyed away from the heart. It was
supposed by the ancients to contain air ; hence the name.
AR-TIC-U-LA'TION (L. articulo, to form a joint). The more or less
morable union of bones, etc. ; a joint.
A-RYT'E-NOID CAR'TI-LA-GES (Gr. dpvraira, arutaina, a pitcher)
Two small cartilages of the larynx, resembling the mouth of a
pitcher.
AS-SIM-I-LA'TION (L. ad, to, and ximilis, like). The conversion of food
into living tissue.
AU-DI'TION (L. audio, to hear). The act of hearing sounds.
AU'DI-TO-RY NERVE. One of the cranial nerves; it is the special
nerve of hearing.
AU'RI-CLE (L. auris, the ear). A cavity of the heart.
BAR'I-TONE (Gr. fiapvS, barus, heavy, and roVoS, tonos, tone). A
variety of male voice between the bass and tenor.
BEL-LA-DON'NA (It. beautiful lady). A vegetable narcotic poison. It
has the property of enlarging the pupil, and thus increasing the
brilliancy of the eye ; so called from its use by Italian ladies.
BI-CUS'PID (L. bi, two, and cuspis, prominence). The name of the
fourth and fifth teeth on each side of the jaw ; possessing two prom-
inences.
BELE. The gall, or peculiar secretion of the liver ; a viscid, yellowish
fluid, and very bitter to the taste.
BRONCH'I (Gr. fipoyxoS, bronkos, the \\vndpipe). The two first
divisions or branches of the trachea; one enters each lung.
BRONCH'I- AL TUBES. The smaller branches of the trachea within
the substance of the lungs, terminating in the air-cells.
BRONCH-I'TIS (from bronchia, and itis, a suffix signifying inflamma-
tion). An inflammation of the larger bronchial tubes ; a " cold"
affecting the lungs.
CAL-CA'RE-OUS (L. calx, lime). Containing lime.
CA-NAL' (L.). In the body, any tube or passage.
CA-NINE' (L. canis, a dog). Name given to the third tooth on **ck
254 GLOSSARY.
side of the jaw ; in the upper jaw it is also known as the eye-tootn.
pointed like the tusks of a dog.
CAP'IL-LA-RY (L. capil'lus, a hair, capitta'ri* hair-like). The name of
the extremely minute blood-vessels which connect the arteries with
the veins.
CAR'BON DIOX-IDB (COt). Chemical name for carbonic acid gas.
CAR-BON'IC A-cro. The gas which is present in the air expired from
the lungs ; a waste product of the animal kingdom, and a food of
the vegetable kingdom.
CAB'DI-AC (Or. xapdia, cardia, the heart). The cardiac orifice of
the stomach is the upper one, and is near the heart ; hence its
name.
CAB-NIV'O-RODS (L. ca'ro, flesh, and w'ro, to devour). Subsisting
upon flesh.
CA-ROT'ID AR-TE-RY. The large artery of the neck, supplying the
head and brain.
CAR'TI-LAGE. A solid but flexible material, formmg a part of the
joints, air-passages, nostrils, etc. ; gristle.
OA'SE-INE (L. ca'seus, cheese). The albuminoid substance of milk
it forms the basis of cheese.
CER-E-BEL'HJM (diminutive for cer'ebrum, the brain). The little brain,
situated beneath the posterior third of the cerebrum.
CER'E-BRUM (L.). The brain proper, occupying the entire upper por-
tion of the skull. It is nearly divided into two equal parts, called
" hemispheres," by a cleft extending from before backward.
CHO'ROID (Gr. xopiov, chorion, a membrane or covering). The mid-
dle tunic or coat of the eyeball.
CHYLE (Gr. jwAdS, chulos, juice). The milk-like fluid formed by the
digestion of fatty articles of food in the intestines.
CHYME (Gr. jv/^oS, ckumos, juice). lue pulpy liquid formed by
digestion within the stomach.
CIL'I-A (pi. of cil'i-um, an eyelash). Minute, vibratile, hair -like pro-
cesses found upon the cells of the air- passages, and other parts that
are habitually moist.
CIR-CU-LA'TION (L. cir'culus, a ring). The circuit, or course of the
blood through the blood-vessels of the body, from the heart to the
arteries, through the capillaries into the veins, and from the veins
back to the heart.
CO-AG-U-LA'TION (L. coag'ulo, to curdle). Applied to the process by
which the blood clots or solidifies.
COCH'LE-A (L. cock' lea, a snail-shellV The spiral cavity of the in-
ternal ear.
GLOSSARY. 255
CONCF'A (Gr. KoyxVt konche, a mussel-shell). The external shell-
shao'jd portion of the external ear.
CON-JUNC-TI'VA (L. con and jurigo, to join together). A thin layer
of mucous membrane which lines the eyelids and covers the front
of the eyeball; thus joining the latter to the lids.
OON-TRAC-TTI/I-TY (L. con and tra'ho, to draw together). The prop
ertv of a muscle which enables it to contract, or draw its extrem-
ities closer together.
OON-VO-LU'TIONS (L. con and wl'w, to roll together). The tortuous
foldings of the extenal surface of the brain.
CON-VUI/SION (L. c&nvel'lo, to pull together). A more or less violent
agitation of the limbs or body.
COR'NE-A (L. cor'nu^ a horn). The transparent, horn-like substance
which covers the anterior fifth of the eyeball.
COR'PUS-CLES, BLOOD (L. dim. of cor'pus, a body). The small bicon
cave disks which give to the blood its red color ; the white cor
puscles are globular and larger.
COS-MET'IC (Gr. KOG/USK), kosmeo, to adorn). Beautifying; applieo
to articles which are supposed to increase the beauty of tn*
skin, etc.
CRA'NI-AL (L. cra'nium, the skulty Pertaining to the skull. Tht
nerves which arise from the brain are called cranial nerves.
CRI'COID (Gr. Hpixos, kri'kos, a ring). A cartilage of the larynx,
resembling a seal-ring in shape.
CBYS'TAL-LINE LENS (L. crystal'lum, a crystal). One of the so-called
humors of the eye ; a double convex body situated in the front part
of the eyeball.
CU'TI-CLE (L. dim. ofcu'tis, the skin). The scarf-skin ; also called
the epider'mis.
CU'TIS (Gr. duvroS, skutos, a skin or hide). The true skin, lying
beneath the cuticle ; also called the der'ma.
DE-CUS-SA'TION (L. decus'sis, the Roman numeral ten, X). A re-
ciprocal crossing of fibres from side to side.
DI'A-PHRAGM (Gr. diacppatitia), diaphrasso, to divide by a partition).
A large, thin muscle which separates the cavity of the chest from
the abdomen ; a muscle of respiration.
D^-FUS'ION OP GASES. The power of gases to become intimately
mingled, without reference to the force of gravity.
DUCT (L. du'co, to lead). A narrow tube ; the tJioracic duct is the
main trunk of the absorbent vessels.
DU-O-DE'NUM (L. duode'ni, twelve). The first division oi the small
intestines, about twelve finders-breadth long.
256 GLOSSARY.
DU'RA MA'TER (L.). Literally, the hard mother; the tough membrane
which envelops the brain.
DYS-PEP'SI-A (Gr. dv$, dm, difficult, and Ttexra), pep' to, to digest). Dif-
ficult or painful digestion ; a disordered condition of the stomach.
E-MUL'SION (L. emul'geo, to milk). Oil in a finely divided state sus-
pended in water.
EN-AM'EL (Fr. email). The dense material which covers tho crown
of the tooth.
EN'ER-GY, Specific, of a Nerve. When a nerve of special sense is
excited, whatever be the cause, the sensation experienced is that
peculiar to the nerve ; this is said to be the law of the specific
energy of the nerves.
^P-I-GLOT'TIS (Gr. ini, epi, upon, and ^AcarrzS, glottis, the entrance
to the windpipe). A leaf-shaped piece of cartilage which covers
the top of the larynx during the act of swallowing.
EX-CRE'TION (L. excer'no, to separate). The separation from the blood
of the waste particles of the body ; also the materials excrrted.
EX-PI-RA'TION (L. expi'ro, to breathe out). The act of forcing air out
of the lungs,
EX-TEN' SIGN (L. ex, out, and ten' do, to stretch). The act of restoring a
limb, etc., to its natural position after it has been tiexed, or bent-
the opposite of Flexion.
FE-NES'TRA (L.). Literally, a window; the opening between the
middle and internal ear.
FI'BRIN (L. ji'bm, a fibre). An albuminoid substance found in the
blood ; in coagulating it assumes a fibrous form.
FLEX'ION (L.flec'to, to bend). The act of bending a limb, etc.
FOL'LT-CLE (L. dim. off of Its, a bag). A little pouch or depression in a
membrane ; it has generally a secretory function.
FUN'GOUS GROWTHS (It. fun' gits, a mushroom). A low grade of vege-
table life.
GAN'GLI-ON (Gr. yayyXiov , ganglion, a knot). A knot-like swell-
ing in the course of a nerve ; a smaller nerve-centre.
GAS'TRFC (Gr. yatfryp, gasler, stomach). Pertaining to the stomach.
GLAND (L. glans, an acorn). An organ consisting of follicles and
ducts, with numerous blood-vessels interwoven ; it separates some
particular fluid from the blood.
^LOS'SO-PHAR-YN-GE'AL NERVE (Gr. Yk(5<5(5a,glossa, the tongue, and
qxxpvyc,, pharunx, the throat). The nerve of taste supplying the
posterior third of the tongue; it also supplies the throat
GLU'TEN (L.). Literally, glue : the glutinous albuminoid ingiedient
of wheat.
GLOSSARY. 25 *i
GRAN'ULE (L. dim. of gra'num, a grain). A little grain; a micro-
scopic object.
GUS-TA'TION (L. gus'to, to taste). The sense of taste.
GUS'TA-TO-RY NERVE. The nerve of taste supplying the front part
of the tongue, a branch of the " fifth" pair.
EI^KM'OR-RIIAGE ^Gr. aina, hai'ma, blood, and pi'jywui, regnumi,
to burst). Bleeding, or the loss of blood.
HEM-I-PLE'GIA (Gr. ^//itfus, hemisus, half, and Tr/l^tftfa?, plexso, to
strike). Paralysis, or loss of power, affecting one side of the body
EIEM'I-SPHERES (Gr. <5(poupa> sphaim, a sphere). Halt a sphere, the
lateral halves of the cerebrum, or brain proper.
HE- PAT' ic (Gr. rfTtap, Jiepar y the liver). Pertaining to the liver.
HER-BIV'O-ROUS (L. her'ba, an herb, and r><> ' ro to devour). Applied
to animals that subsist upon vegetable food.
HU'MOR (L.). Moisture: the humors are transparent contents of the
eyeball.
HY-DRO-PHO'BI-A (Gr. vdop, hudor, water, and <pofira y pJiobeo, to
fear). A disease caused by the bite of a rabid dog or other animal.
In a person affected with it, convulsions are occasioned by the sight
of a glittering object, like water, by the sound of running water,
and by almost any external impression.
HY'GI-ENE (Gr. vyiEia, huygieia* health) The art of pres^rvin^
health and preventing disease.
HY PER-O-PI-A. Abbreviated from HY PER-MST-RO'PI-A (Gr. Si-nep,
huper, beyond, verpov, metron, the measure, and <></>, ap.% the eye).
A defect of vision dependent upon a too short eyeball ; so called
because the rays of light are brought to a focus at a point behind
the retina ; the true " far sight."
LN-CI'SOR (L. ind'do, to cut). Applied to the four front teeth of both
jaws, which have sharp cutting edges.
LN'CUS (L). An anvil ; the name of one of the bones of the middle
ear.
LN-SAL-I-VA'TION (L. in, and salfva, the fluid of the mouth). The
mingling of the saliva with the food during the act of chewing.
IN-SPI-RA'TION (L. in, and spi'ro, spira'tum, to breathe). The act of
drawing in the breath.
IN-TEG'U-MENT (L. in, and te'go, to cover). The skin, or outer covering
of the body.
IN-TES'TINE (L. m'tus, within). The part of the alimentary canal
which is continuous with the lower end of the stomach ; also called
the intestines, or the bowels.
I'RIS (L. fris, the rainbow). The thin muscular ring which lies be
2-58 GLOSSARY.
tween the cornea and crystalline lens, and which gives the eye
its brown, blue, or other color.
JD'GU-LAR (Tj.ju'gulum, the throat). The name of the large veins
which run along the front of the neck.
LAB'Y-RINTH (Gr. kafidpivSoS, laburirithos, a building with many
grinding passages). The very tortuous cavity of the inner ear,
comprising the vestibule, semicircular canals, and the cochlea.
LACH'RY-MAL APPARATUS (L. lach'ryma, a tear). The organs for
forming and conveying away the tears.
LAC'TE-ALS (L. lac, lac'tis, milk). The absorbent vessels of the small
intestines ; during digestion they are filled with chyle, which has
a milky appearance.
LA-RYN'GO-SCOPE (Gr. Xdpvyt,, larunx, the larynx, and tixoTteca,
akopeo, to look at). The instrument by which the larynx may be
examined in the living subject.
LAR'YNX (Gr.). The cartilaginous tube situated at the top of the
windpipe, or trachea ; the organ of the voice.
LENS (L.). Literally, a lentil ; a piece of transparent glass or other sub-
stance so shaped as either to converge or disperse the rays of light.
Lie A-MENT (L. li'go, to bind). A strong, fibrous material binding
bones or other solid parts together; it is especially necessary to
give strength to joints.
LIG'A-TURE. A thread of silk or other material used untying around
an artery.
LYMPH (L. lym'pTia, spring- water). The colorless, watery fluid con-
veyed by the lymphatic vessels.
LYM-PHAT'IC VESSELS. A system of absorbent vessels.
MAL'LE-US (L.). Literally, the mallet ; one of the small bones of the
middle ear.
MAR' ROW. The soft; fatty substance contained in the central cavities
of the bones : the spinal marrow, however, is composed of nervous
tissue.
MAS-TI-CA'TION (L. mas'tico, to chew). The act of cutting and grind
ing the food to pieces by means of the teeth.
ME-DUL'LA OB-LON-GA'TA. The " oblong marrow," or nervous cord,
which is continuous with the spinal cord within the skull.
MEM-BRA'NA TYM'PAN-I (L.). Literally, the membrane of the drum ;
a delicate partition separating the outer from the middle ear ; it is
sometimes incorrectly called the drum of the ear.
MEM'BRANE. A thin layer of tissue serving to cover some pan ol
the body.
MT'CRO-SCOPJC (Gr. ntKpot, mikm*^ small, and tSwirsoo, skopeo, to
GLOSSARY. 259
look at). An optical instrument which assists hi the examinatioD
of minute objects.
MO'LAR (L. mo'la, a mill). The name applied to the three back teeti
of each side of the jaw ; the grinders, or mill-like teeth.
MO'TOR (L. mo'veo, mo' turn, to move). Causing motion ; the namf
of those nerves which conduct to the muscles the stimulus which
causes them to contract
Mu'cous MEM'BRANE. The thin layer of tissue which covers those in-
ternal cavities or passages which communicate with the external air.
Mu'cus. The glairy fluid which is secreted by mucous membranes,
and which serves to keep them in a moist condition.
MY-O'PI-A (Gr. X/I'GJ, muo, to contract, and o>^, ops, the eye). A de-
fect of vision dependent upon an eyeball that is too long, rendering
distant objects indistinct ; near-sight.
NA'SAL (L. na'sus, the nose). Pertaining to the nose ; the 7iasa>
cavities contain the distribution of the special nerve of smell.
NERVE (Gr. vEvpov, neuron, a cord or string). A glistening, white
cord of cylindrical shape, connecting the brain or spinai cord with
some other organ of the body.
NERVE CELL. A minute, round and ashen-gray eel 1 found in the
brain and other nervous centres.
NERVE FI'BRE. An exceedingly slender thread of nervous tissue
found in the various nervous organs, but especially hi the nerves ;
it is of a white color.
NU-TRI'TION (L. nu'trio, to nourish). The processes by which the
nourishment of the body is accomplished.
CE-SOPH'A-GUS (Gr.). Literally, that which carries food. The tube
leading from the throat to the stomach ; the gullet.
O-LE-AG'I-NOUS (L. o'leum, oil). Of the nature of oil : applied to an
important group of food-principles the fats.
OL-FAC'TO-RY (L. olfa'cio, to smell). Pertaining to the sense of smell
OPH-THAL'MO-SCOPE (Gr. o<p3#Ayuo, ophthalmos, the eye, and 6uo-
new, skopec, to look at). An instrument devised for examining the
interior of the globe of the eye.
OP'TIC (Gr. OUTGO, opto, to see). Pertaining to the sense of sight.
OR'BIT (L. or'tts, the socket). The bony socket or cavity in which
the eyeball is situated.
OS'MOSE (Gr. Go<5ju6s,08mos, a thrusting or impulsion). The process
by which liquids are impelled through a moist membrane.
OS'SE-OUS (L. os y a bone). Consisting of, or resembling bone.
PAL' ATE (L. polo? turn, the palate). The roof of the mouth, consisting
of the hard and soft palate.
U GLOSSARY.
I/MVK. Relating to the palm of the hand.
LN'CRE-AS (Or. TraS, aravro'?, pa*, ptinton, all, and xpcat,
flesh). A long, flat gland situated near the stomach ; in the lowei
inimals the analogous orc;an is called the sweet-bread.
-FIL'L^E (L. papil'la]. The minute prominences in which termi-
nate the ultimate fibres of the nerves of touch and taste,
.-RAI/Y-SIS. A disease of the nervous system marked by the !./t*
}f sensation, or voluntary motion, or both ; palsy.
R-A-PI.E GI-A (Gr. icapait\.rf66oo t parapleso t to strike arinsaV A
brm of paralysis affecting the lower half of the body.
-TKL'LA (L dim. of pafina, a pan). The knee-pan ; a small
tone.
:i/vi8 (L.). Literally a basin ; the bony cavity at the lower part of
the trunk.
:P'SIN (Or. iteicrooy pepto, to digest). The organic principle of the
gastric juice.
;R-I-STAI/TIC MOVEMENTS (Gr. irepi6re\\co, perbtello, to con tract).
Flie slow, wave-like movements of the stomach and intestines.
SR-I-TO-NE'UM (Gr. 7rf/a/riVo>, peritrino, to stretch around). In.
investing membrane of the stomach, Intestines, and oth-r ahdom-
nal organs.
:R-SPI-RA'TION (L. perujn'ro, to breathe through). The sweat, or
watery exhalation of the skin; when vi called
perspiration, when invisible, it is called intenribU pvrs
S'TROUB (Gr. ne r pa t petra, a rcxik). The name of the hard portion
of the temporal bone, in which is situa'.ol UK drum of the ear and
labyrinth.
LAR'YNX (Gr. <papvy\, pluirunj-, the throat). The cavity bet
the back of the mouth and gullet
IYB-I-OL'O-IY (Gr. <pv6t$, phui*, nature, and Ati^oS, bgo* t a dis-
course). The science of the functions of living, organized beings.
'A MA'TKR (L.). Literally, the tender mother; the innermost of the
three coverings of the brain. It is thin and delicate ; hence the
name.
jEu'RA (Gr. itA.cvpcr, a rib). A membrane covering the lung and
lining the chest. There is one for each lung.
.KU'KI-SY. An inflammation affecting the pleura.
JEU-MO-OAS'TRIC (Gr. irvevft&v , pneumon, the lun^s, and ya6rtjp,
gatter, the stomach). The name of a nerve distributed to the lungs
and stomach ; it is the principal nerve of respiration.
<BU-MO'NIA (Gr.). An inflammation affecting the air-cells of the
lungs.
GLOSSARY.
l*RE8-n** O'FI-A (Or. TtpstiftvS, preabu*, old, and oS#, ops % the eye
A defect of the accommodation of the eye, caused by the hardei
ing of the crystalline lens ; the " far-sight" of adults and ape
persons.
PROC'KSS (L. prof e do, proctit'miK^ to proceed, to go forth). Any pn
jectiou from a surface. Also, a method of performance ; a pr<
cedure.
PTY'A-LIN (Or. xrva\or, ptuatvn, saliva). The peculiar
ingmlient of the saliva,
PUL'MO-NA-RY (L. putmo, puhno'ni*, the lungs). Pertaining to tk
lungs.
PULSE (L. pcFlo, pul'mm, to beat). The striking of an artery againi
the fi nirer, occasioned by the contraction of the heart, commonl
felt af the wrist.
Pr'riL (L. ptipffla). The central, round opening in the iris, throng
which light passes into the depths of the eye.
PY-LO'RUS (Or. irvAttpJs, pulorog, a gate-keeper). The lower opec
ing of the stomach, at the beginning of the small intestine.
I.EZ ACTION. An involuntary action of the nervous system, I
which an external impression conducted by a sensory nerve
reflected, or converted into a motor impulse.
RES PI-RA'TION (L. reJpiro, to breathe frequently). The functin
of breathing, comprising two acts: inspiration^ or breathing in, an
erpmifwn, or breathing out
UET'I-NA (L. rr'fc, a net). The innermost of the three tunics or coa
of the eyeball, being an expansion of the optic nerve
fcAC'CHA-RiNE (L. aaScharum, sugar). Of the nature of sugai
applied to the important group of food substances which embrace
the different varieties of sugar, starch, and gum.
I'VA (L.). The moisture or tluids of the mouth, secreted by tl:
iry glands, etc.
SCLH-ROT'IC (Or. d*A//po$, tklero*, hard). The tough, fibrous outi
tunic of the eyeball
SR-BA'CEOUB (L. sebum, faf). Resembling fat, the name of tne oil
hecretion by which the skin is kept flexible and soft.
SK-CRE'TION (L. necer'no, necrf'tum, to separate). The process <
separating from the blood some essential important fluid; vvhic
fluid is also called a secretion.
.-KM-I-CIR'CC-LAK CANALS. A portion of the internal ear.
-A'TION. The perception of an external impression by the nej
vous system ; a function of the brain.
HEN-SI-BIL'T-TV. GKNKHAI The rou-T possessed by nearly all par
262 GLOSSARY.
of the human body of recognizing the presence of foreign objects
that come in contact with them.
SB'RUM (L.). The watery constituent of the blood, which separates
from the clot during the process of coagulation.
SKEL'E-TON (Gr.). The bony framework of an animal, the different
parts of -which are maintained in their proper relative positions.
SPEC'TRO-SCOPE (from spec'trum and ^HOTCEGO^ scopeo, to examine the
spectrum). An instrument' employed hi the examination of the
spectrum of the sun or any other luminous body.
SPHYG' MO-GRAPH (Gr. 6(pvyiJ.6$, sphugmos, the pulse, and ypacpoo^
grapJrf, to write). An ingenious instrument by means of which
the pulse is delineated upon paper.
STA'PES (L.). Literally, a stirrup ; one of the small bones of the tym-
panum, or middle ear, resembling somewhat a stirrup in shape.
SYM-PA-THET'IC SYSTEM OP NERVES. A double chain of nervous
ganglia, connected together by numerous small nerves, situated
chiefly in front of and on each side of the spinal column.
SYN-O'VI-A (Gr. 6vv, sun, and cooV, oon, resembling an egg). The
lubricating fluid of joints, so called because it resembles the white
of egg.
SYS'TO-LE (Gr. dvtirsA.A.a), sustello, to contract). The contraction of
the heart, by which the blood is expelled from that organ.
TAC'TILE (L. tac'tus, touch). Relating to the sense of touch.
TEM'PO-RAL (L. tem'pus % time, and tem'pora, the temples). Pertain-
ing to the temples ; the name of an artery : so called, because the
hair begins to turn white with age in that portion of the scalp.
TEN'DON (L. ten'do, to stretch). The white, fibrous cord or band by
which a muscle is attached to a bone ; a sinew.
TET'A-NUS (Gr. TEIVGO, teino, to stretch). A disease marked by per-
sistent contractions of all or some of the voluntary muscles ;
those of the jaw are sometimes solely affected the disorder is then
termed locked-jaw.
THO'RAX (Gr. Soapa^, thorax, a breastplate). The upper cavity of
the trunk of the body, containing the lungs, heart, etc. ; the
chest.
THY'ROID (Gr. $u/oo's, thureos, a shield). The largest of the carti-
lages of the larynx ; its angular projection hi the front of the neck
is called " Adam's apple."
TRA'CHE-A (Gr. rpaxvS, trachus, rough). The windpipe, or the
largest of the air-passages ; composed in part of cartilaginous
rings, which render its surface rough and uneven.
TBANS-FU'SION (L. transfun'do^ to pour from one vessel to another).
OL08RARY. '463
The operation of injecting blood taken from one person into the
veins of another; other fluids than blood are sometimes used.
TRICH-I'NA SPI-RA'LIS. (L.) A minute species of parasite or worm,
which infests the flesh of the hog, and which may be introduced
into the human system by eating pork not thoroughly cooked.
TYM'PA-NUM (Gr. Tv/Linavov, tumpanan, a drum). The cavity of
the middle ear, resembling a drum in being closed by two mem-
branes, and in having communication with the atmosphere.
U'vn-LA (L. urn, a grape). The small pendulous body attached to
the back part of the palate.
VAS'CU-LAR (L. vas'culum, a little vessel). Pertaining to, or contain-
ing blood-vessels.
VE'NOUS (L. wfna, a vein). Pertaining to, or contained within a
vein.
VEN-TI-LA'TION. The introduction of fresh air into a room or build-
ing, in such a manner as to keep the air within it hi a pure condi-
tion.
VEN-TRIL'O-QUISM (L. writer \ the belly, and lo'quor, to speak). A
modification of natural speech by which the voice is made to
appear to come from a distance. The ancients supposed that the
voice was formed in the belly ; hence the name.
VEN'TRI-CLES of the heart. The two largest cavities of the heart,
situated at its apex or point
VER'TE-BRAL COLUMN (L. ver'tehra, a joint). The back-bone, con
sisting of twenty-six separate bones, called vertebrae, firmly jointed
together ; also called the spinal column and spine.
VES'TI-BULE. A portion of the internal ear, communicating with the
semicircular canals and the cochlea; so called from its fa -tied
resemblance to the vestibule or porch of a house.
VIL'LI (L. vil'lu*, the nap of cloth). Minute thread-like projection-
found upon the internal surface of the small intestine, giving it t\
velvety appearance.
VIT'RE-OUS (L. vi'trum, glass). Having the appearance of glass ;
applied to the humor occupying the largest part of the cavity of
the eyeball.
VIV-I-SEC'TION (L. vi'ws, alive, and se'co, to cut) The practice of
operating upon living animals, for the purpose of studying some
physiological process.
VOCAL CORDS. Two elastic bands or ridges situated in the larynx ;
they &re the essential parts of the organs of tl e voice.
INDEX.
A.
PAGE
Absorbent vessels 97
Absorption
by blood-vessels
by the lacteals
of the food 96
Accommodation, function of 213
Achilles, tendon of. 27
Adam's apple 229
Air, atmospheric 131
Changes in, in respiration. 132
Carbonic acid in 138
Composition of 131
Dust in the 187
Effects of impure 139
Impurities in 136
Matters in the expired 13'2
Provision for purifying. 141
Renovation by ventilation 142
Air-cells of the lungs 125
Air-passages 125
Albinos 44
Albumen 58
of the blood 102
Albuminoid substances 57
Varieties of 57
Properties of. 57-58
Albuminose 94
Alcoholic liquors 77
Physiological action of 78
Alimentary canal 81
Animal functions 148
Animal heat 143
how produced 143
regulated by perspiration 145
Animals, relative strength of 28
Apoplexy 171
Aqueous humor 210
Arachnoid membrane 152
Arbor vitie 154
Arterial blood 107-135
differs from venous 135
Arteries 114
Arrangement of 115
Carotid 116
Distribution of 115
Pulsation of. 115
Radial 116
Temporal 1 16
Arytenoid cartilage 229
Asphyxia 250
Assimilation 80, 121
Audition 215
TAG*
Auditory canal 218
nerve 222
Auricles of the heart 109
B.
Back-bone 21
Bathing 47
Importance of. 47
Time and manner of 49
Baths 48
Different kinds of , . 48
Belladonna 206
dilates the pupil 206
Use as a cosmetic 206
Bile ; 95
Secretion of, in the liver 95
Accumulation of, in the gall-bladder 95
Uses of 95
Biliary duct 95
Bladder, Gall- 95
Bleeding, how stopped 121
Blind-spot 207
Blood 101
Arterial 107-135
Change of color 107
Circulation of. 107, 133
Coagulation of 105
Composition of 102
corpuscles 102, 103
fluid 105
Microscopic appearance of. 102
Respiratory changes in 133
Uses of the 105
Venous 107, 135
Blood-vessels 114, 118
Absorption by 96
Injuries to the 121
Body, renovation of the 66
Bones J5
Form and composition of 16
Growth of. 22
Microscopic structure of 17
Repair of. 23
Structure of 17
Uses of... 15
Bowels 94
Brain 150
Anatomical structure of 152
Function of the 172
Injuries of the 173
Membranes of the 152
Reflex action of the 174
266
IKDEX.
PAGE
Bread 72
Bronchial tubes 125
Bronchitis 128
C.
Canals, Semicircular
Capillary blood-vessels ...118
Circulation in the
Carbonic acid . 132
exhaled from the lungs 132
in the air 138
retention in the blood 134
Cartilage 20
Arytenoid 229
Cricoid 229
Thyroid 229
Casein 58
Cataract 210
Cells, Nerve 150, 159
Ciliated.... 128
Cerebellum 153
Function of the 172
Cerebro-spinal nervous system 1 50
Cerebrum 152
Function of the 172
Cheese 58
Chest, Framework of. 19
Contents of the 19
Chocolate 77
Chorea 169
Choroid coat of the eye ... . . 204
Chyle 95
Chyme 94
Cilia 1*5-
Circulation 107
in the frog's foot 119
of the blood 107
Rapidity of 120
through the heart 112
through the lungs 123
Clothing 51
Coagulation of milk 58
of the blood 104
Cochlea 223
Coffee 75
Effects of 75, 76
Collar-bone 19
Color-blindness 209
Column, Spinal 21
Combustion, Spontaneous 145
Complexion 44
Concha of the ear 217
Conjunctiva 200
Contraction of heart Ill
of muscles 27
Convulsions 16!)
Cooking 70
Cords, Vocal 126,230
Cornea 203
Corpuscles, Blood 102
Cosmetics 51
Cranial ganglia 150
Functions of 171
Cranial nerves 154
Cranium 19
Cricoid cartilage 229
Crystalline lens 209
Uses of 210
Cuticle... 41
Function of. ..183
Cutis . 42
B,
Decussation of motor and sensory
fibres of spinal cord 164
Dentition of infancy 82
Diaphragm, Movements of the, in
respiration 128, 129
Diastole of the heart Ill
Diet, Mixed 66, 85
Necessity for changing. 67
Necessity of a regulated 62
The best 63
Digestion 80
Circumstances affecting 97
Gastric 93
Intestinal 94
Nature of 81
Organs of , 81-91
Drowning 250
Duct, Biliary 95
Nasal 201
Pancreatic 95
Thoracic 97
Dura Mater 152
E.
Ear .. 217
External 217
Internal 2-2-2
Middle 219
Foreign bodies in 225
Drum of the 219
Bones of the 220
Ear-sand 223
Ear-stones 223
Ear-wax 219
Eggs 68
Composition of 68
Emulsion of fats, in digestion 95
Enamel of the teeth 82
Epiglottis 126,229
Uses of 126, 220
Eustachian tube 221
Exercise 30
Different modes of 31
Effects of 30
Importance of. 30
Open-air 33
Expiration 128
Movements of. 12!)
Extensor muscles 2ii
Eye 198
Eyeball 203
Eyelashes 200
Eyelids 200
F.
Fats 59
Emulsion of 59
Source of, in food 59
f'enestra ovalis 224
Tibres, Muscular 25
INDEX,
267
PAGE
, Nervous 149
Fibrinein food 58
of the blood 103
Fish, as food 71
Flexor muscles 26
Food 53
Animal 67
Daily quantity of. 65
Ingredients of. 54-62
Necessity for 64
Source of 53
Vegetable 71
189
0.
Gall-bladder
Ganglia, cranial. Functions of the. .
Gases, Interchange of, in the lungs.
Gastric digestion
Gactric juice
Action of.
Daily quantity of. ....
General sensibility
Glands, Perspiratory
Salivary
Sebaceous
Glossary
Glosso-pharyngeal nerve
Gullet
Gum
as food
Gustatory nerve
Gymnastics
for schools and colleges
H.
Hair... . 42
Uses of 44
Hearing, Sense of 215
Protection of 2-24
Heart 107
Cavities of the 109, 110
Circulation through the 112
Frequency of action 112
Movements of the Ill
Valves of the 112
Heat, Animal 143
Production of . 143
Regulation of 145
Hemiplegia. . . 165
Humor. Aqueous 210
Crystalline 209
Vitreous 210
Hunger 65
Seat of the sensation of 65
Hydra 149
Hydrophobia 169
Hygiene 13
Hyperopia 212
I.
Incus 220
Inorganic substances in food 54
Insalivation 86, 88
Insensible perspiration 46
PAGE
Inspiration 128
Intestinal juice 95
Action of 96
Intestines 94
Complete digestion in the small.. 94
Villi of the IXi
Iris... 205
Function of 205
Iron 56
Proportion in the blood 57
Proportion in the food 57
J.
Joints 19
Varieties of 20
Juice, gastric 91
Intestinal 95
Pancreatic , 95
Labyrinth
Lachrymal canals
gland
Lacteals
Absorption by
Lactic acid in gastric juice
Lactometer
Large intestines
Laryngoscope
Larynx 125,
Production of the voice in the.126,
Lens, crystalline
Ligaments
Light, theory of
Lime in the bones
in the food
Importance of
Liver
Secretion of the
Locked jaw
Long-sight ,
Lungs.
Capacity of
Structure of
Lymph
Lymphatic vessels.
201
201
94
231
19
197
16
56
56
95
95
169
212
123
130
125
97
97
OT.
Magendie, on pain 181
Magnesia, Compounds of, in food... 57
Malleus 220
Marrow of the bones 17
Mastication 82
Importance of 88, 89
Meats 68
The cooking of. 69
The preservation of 69
Membrane of the tympanum 219
Medulla oblongata 154
Function of the 171
Microscope 236
The value of the 236
Simple 237
Compound 239
The use of the 239
268
INDEX.
PAGE
Milk 68
Composition of 68
Specific gravity of 68
Milk-teeth '. 82
Mucous membrane of air passages. 127
Muscles 25
Function of the 25
Flexion and extension of 26
Voluntary and involuntary 26
Muscular contraction 27
fibres 25
sense 188
Myopia 212
N.
Nails 42
Uses of the 44
Nasal cavities 192
duct 201
Nerve, Auditory 222
Glossopharyn^eal 189
Gustatory. 189
Olfactory 193
Optic 197
Sympathetic 158
Nerve cells ...150, 159
Nerve fibres 149
Nerves, Cranial 154
Spinal 156
Functions of the 160
Sensory, functions of the 100
Motor, functions of the 1 60
Sympathetic system of 158
Nervous system 148, 149
Cerebro-spinal 150
Nervous tissue, Properties of 159
Nose 192
Nutrition, Processes of 80
O.
(Esophagus 90
Oil, Sources of, in food 59
Old-sight 215
Olfactory nerve 193
Optic nerve 197
Orbicular bone 220
Orbit of the eye 199
Organic substances as food 5762
Organs of circulation 107
Digestion 8191
Respiration 123
Sight : 198
Voice 228
Oxygen 131
Amount of, consumed in respira-
tion 132
Continually supplied to the atmo-
sphere 141
P.
Pain, Relations of, to pleasure 181
Sensation of 180
Uses of 180
Pancreatic juice 95
Uses of... . 95
PAGE
Pancreatin 95
Paraplegia 163
Parlor gymnasium 36
Passages, Air 125
Pelvis 19
Pepsin 92
Peristaltic action of the stomach... 92
Peritoneum 94
Perspiration, Daily amount of 46
Sensible and insensible 46
Uses of 46, 145
Perspiratory glands 45
Physical strength 29
Culture 33
Physiology 11
Animal 11
Comparative 11
Human 11
Vegetable 11
Pia mater 153
Plasma of the blood 102
Pleura 124
Pleurisy 128
Pneumo gastric nerve 171
Pneumonia 128
Poisons and their antidotes 247
Potash in the blood 57
Potato 73
Presbyopia 215
Preservation of the teeth 85
Ptyalin 88
Pulsation of the heart 113
of the arteries 116
Pulse 115
Form of the 116
Writer 116
Pylorus 90
R.
Radial artery 116
Red corpuscles of the blood 102
Reflex action of the spinal cord .. . 165
Requisites for 167
Uses of 167, 170
Causing convulsions 169
Objects of 170
of the brain 174, 175
Rennet 58
Respiration 123
Change of blood in 123133
Frequency of 129
Movements of 128
Obj ect of 123
Organs of 123
Respiratory labor 135
Rest, necessity for 38
Retina 206
Retinal light ... 207
Ribs, Movements of, in respiration. 128
S.
Saccharine substances 60
Saliva 86
Importance of. 88
Secretion of 86
Salivary glands 86, 87
I^DEX.
269
PAGE
Salt, Common 55
Importance of 56
Sclerotic coat of the eyeball 204
Sebaceous glands 44
Secretion of 45
Semicircular canals 223
Sensation of pain ISO
.Relations of, to pleasure 181
of temperature 187
of weight 188
Modification of 178
Production of 177
Variety of 178
Sense of hearing 215
sight 196
smell 192
taste 189
touch 184
Sense, muscular 188
thermal 187
Senses, Special 177
Sensibility, General 179
Short-sight 212
Sinews 27
Sight, Sense of 196
Organs of 198
Skeleton ... 19
Skin 41
Structureof 41
Skull 19
Uses of the ... 19
Sleep, Necessity for 38
Amount required , 39
Small intestines 94
Smell, Sense of 192
Nerve of 193
Uses of 194
Soda in the food , 57
Sound, Production of. 215
Special senses 177
Spectroscope 104
Speech 227
Relation of, to the sense of hear-
in' .-^^^^^^^^^^^
" 116
21
Spinal cord 155
Decussadon of the 164
Direction of fibres in 164
Functions of the 162
Nerves of 156
Reflex action of 165
Spontaneous combustion 145
Stapes 220
Starch 61
Its change into sugar 61
Different kinds 61
Effectot boiling 61
Microscopic appearance 61
Stimulating substances 62
Stomach, 90, 92
Digestion 93
Movements of 92
Secretion of 92
St. Vitus' dance 169
Sugar 60
Varieties 60
Sources of 61
Sphygmograph . .
Spinal column.
PAGE
Sun-bath 50
Sympathetic system of nerves 158
Synovia 20
Systole of the heart Ill
T.
Taste, Association of 190
Education of. 191
Organ of 188
Sense of 189
Tea, Effect of . . .76
Kinds of ?<?
Tears 201
Escape of the 201
Teeth 82
Temporary set of 82
Permanent set of 83
Bicuspid 83
Canine 83
Incisor 83
Molar 84
Arrangement of 85
of different animals 85
Preservation of 85
Temperature of the body 140
Extremes of 146
Sensations of 187
Tendon of Achilles 27
Tendons 27
Tetanus 16J
Thermal 50
Thermae sense 187
Thirst 65
Thoracic duct 97
Thorax 19
Thyroid cartilage : 229
Tissues, intimate structure of the. . 236
Human 244
of the lower animals 245
Tongue 188
Nerves of 18&
Sensibility 189
Touch, Delicacy of 186
Organs of 183
Sense of 184
Trachea 125
Transfusion 106
Trichina spiralis 71
Trunk 19
Tympanum of the ear 219
Membrane of . . 219
V.
Valves of the heart 112
of the veins 117
Vapor, Animal, in breath 132
Vegetable food 71
Vegetative functions 148
Veins 117
Valves of 117
Venous blood 135
Changes of, in respiration 133
Ventilation 142
Ventricles of the larynx 229
of the heart 110
Ventriloquism 235
270
INDEX.
PAGE
Vertebrae 21
Vestibule of the internal ear 223
Villi of the intestines ... 96
Absorption by 96
Vital knot 171
Vitreous humor 210
Vocal cords 126, 230
Observation of, with laryngo-
scope 231
Voice 227
Organ of 228
Production of 232
Varieties of 333
W. PAG
Water 74
Action of, on lead 75
Chemically pure 74
Croton 74
exhaled with the breath 132
from springs and wells 74
Proportion of, in the blood 55
of, in the tissues and
fluids of the body 54
Ridgewood 74
Walking, as a means of exercise ... 31
White corpuscles of the blood 104
Wisdom teth 84