APPLETONS’ 
SCIENCE TEXT-BOOKS. 
ANATOMY, PHYSIOLOGY, 
HYGIENE. APPLETONS’ SCIENCE TEXT-BOOKS. 
The following works of this new series will be im- 
mediately issued ; others are to follow : 
The Elements of Chemistry. 
By Prof. F. W. CLARKE, 
Chemist of the United States Geological Survey. 
The Essentials of 
Anatomy, Physiology, and Hygiene. 
By ROGER S. TRACY, M. D., 
Author of “ Handbook of Sanitary Information for Householders,” 
Sanitary Inspector of the New York City Health Department. 
A Compend of Geology. 
By JOSEPH LE CONTE, 
Professor of Geology and Natural History in the University of 
California ; author of “ Elements of Geology,” etc. 
Elementary Zoology. 
By C. F. HOLDER, 
Fellow of the New York Academy of Sciences, Corresponding 
Member Linnsean Society, etc. ; 
and J. B. HOLDER, M. D., 
Curator of Zoology of American Museum of Natural History, 
Central Park, New York. General Plan of the Circulation  Scicntx Cwt-Ibahs 
THE ESSENTIALS 
OF 
ANATOMY, PHYSIOLOGY, AND 
HYGIENE 
A TEXT-BOOK FOR SCHOOLS AND ACADEMIES 
BY 
ROGER S. TRACY, M. D. 
SANITARY INSPECTOR OF THE NEW YORK CITY HEALTH DEPARTMENT; 
AUTHOR OF “ HAND-BOOK OF SANITARY INFORMATION 
FOR HOUSEHOLDERS.” 
NEW EDITION, REVISED AND ENLARGED 
NEW YORK 
D. APPLETON AND COMPANY 
I, 3, AND 5 BOND STREET 
18 86 Copyright, 1884, 1886, 
By D. APPLETON AND COMPANY. PREFACE. 
It has been my aim in preparing this volume to 
compress within the narrowest space such a clear 
and intelligible account of the structures, activities, 
and care of the human system as is essential for the 
purposes of general education. I have also sought 
to present the facts and principles of the subject in 
such a natural order as will best subserve the true 
ends of scientific education. Useful books of in- 
formation upon physiology are already numerous, 
but they are too generally deficient in making the 
science valuable as a means of mental training. Of 
course, the great object of physiology is to teach how 
to preserve health, but this is not best done by 
merely memorizing rules. The rules must be sup- 
ported by reasons, and if there is not some thorough 
understanding of the mechanism and powers of the 
human body, such as will task the efforts of the 
student, the real fruits of knowledge will not be 
gained. I have accordingly given prominence to 
the anatomical and physiological facts which are 
necessary preliminaries to instruction in hygiene, 
and in the reasonings upon these facts I have aimed 
to attract and interest the pupil, to teach him some- 
thing of the scientific methods of approaching the VI 
PREFACE. 
subject, and to connect new acquisitions logically 
with those already gained, so that the knowledge 
of the subject may become, as it were, organized 
into faculty in the minds of the students. So im- 
portant has it seemed to me to impress deeply upon 
the pupil’s mind the laws of connection and depend- 
ence among the various parts of the living system 
that l have thought it best to present this view, in 
outline, at the very outset. I have, therefore, pre- 
fixed to the volume a General Analysis, which, 
while it serves as a table of contents, is interspersed 
with running comments explaining the general re- 
lations of the different organs and processes, and I 
recommend that this analysis be carefully read by 
the pupil, so that he may become familiar with its 
argument before proceeding to the detailed study 
of the text. 
One of the greatest modern reforms in scientific 
study is undoubtedly that which makes it more 
and more objective, so that the student shall con- 
stantly confirm the knowledge he gets from the 
book by reference, as far as possible, to the objects 
themselves, making his acquaintance with them 
direct, and his information real. The various sci- 
ences lend themselves to this mode of study in 
different degrees; chemistry and physics favoring 
experiment, and botany offering systematic obser- 
vation more than any other scientific subjects. 
Physiology is less favorable to the objective method. 
For the purpose of ordinary education, it must be 
chiefly taught from the book, with such accompani- 
ments of lectures and illustrations by charts as the 
circumstances will allow. But even here much may 
be done to give the pupil more correct ideas of the PREFACE. 
VII 
elements of the subject than can be obtained from 
the book alone. A good manikin is an invaluable 
help to the popular study of anatomy and physiol- 
ogy. Human dissection being out of the question, 
the manikin, which can be taken to pieces so as to 
show all the organs in their situations, connections, 
and relative dimensions, will afford the pupil a vivid 
and exact conception of the dependent parts of the 
living body, and make his physiological knowledge 
truthful and actual. A manikin for school pur- 
poses costs about $250, and may be imported from 
Paris,* where they are made, free of duty for educa- 
tional institutions. 
A great deal is also to be learned from such 
rough dissections of organic tissue and structures 
as may be made anywhere. Every butcher’s shop 
is full of specimens of all parts of animals, that can 
be cheaply obtained for examination, and parents 
and teachers should encourage pupils to make such 
rude dissections as are practicable, and will help to 
give correct ideas of the relations and functions of 
the different organs. 
The study of the minuter parts of organized 
beings with the microscope, histology as it is called, 
has come into great prominence in modern times, 
and may be said to have revolutionized the science 
of life. No class in physiology should be without a 
microscope for the direct study of cell-structures 
and the finer tissues of both plants and animals. A 
suitable instrument, with a magnifying power of 
three hundred and fifty diameters, will show the 
circulation in the web of a frog’s foot, and open a 
new world of fascinating and wonderful observation, 
* Auzoux is the principal manufacturer of these models. VIII 
PREFACE. 
while it may be bought for sixteen dollars. Micro- 
scopic preparations of blood-corpuscles, muscular 
and nervous tissues, and sections of organs may be 
got for about twenty cents apiece, but it is desirable 
that the pupil should not rely upon these, but should 
learn the method of preparing and mounting objects 
himself. The microscope is not to be recommended 
as a mere toy to amuse idle curiosity ; there is work 
connected with it which is in a high degree educa- 
tional. It cultivates critical observation and careful 
manipulation, and is invaluable as a means of self- 
education. The little hand-book of Phin* will be 
found useful in guiding beginners with this instru- 
ment . 
The illustrations are largely copied from Gray’s 
“ Anatomy,” though I am also indebted to Dalton’s 
“ Physiology,” to Flint’s “ Physiology,” to Ranney’s 
“Applied Anatomy of the Nervous System,” to 
Riidinger’s “ Topographisch-Chirurgische Anato- 
mie,” and to Neumann’s “ Hand-Book of Skin Dis- 
eases.” Many of the figures I have altered to suit 
my purpose, and the necessary descriptions are so 
inscribed upon or near them as to do away with 
the inconvenience of lettered references. A few of 
the cuts are original. 
For the use of material other than the illustra- 
tions, I have to acknowledge my indebtedness to 
Flint, Beaumont, Strieker, Neumann, Riidinger, 
Paget, Maudsley, Reynolds, Aitken, Huxley, Soel- 
berg Wells, Uhle and Wagner, Foster, and espe- 
cially to Dalton. 
R. S. T. 
March I, 1884. 
* “ A Book for Beginners with the Microscope,” 30 cents. GENERAL ANALYSIS. 
Part I.—Introduction. 
Gives certain necessary definitions, and describes the cell 
and its properties as being the real basis of all more fully 
developed living organisms. 
CHAPTER PAGE 
1. Definitions 1 
II. Minute Structure of the Body ..... 3 
Part II—Organs of Motion. 
A large body entirely composed of cells would be a soft, 
jelly-like mass, incapable of locomotion or of self-protection. 
But to obtain food it must be able to move from place to place, 
and also to move its different parts with reference to one an- 
other. For these purposes there must be points of resistance 
and points of support. These points are furnished by the 
bones, which act as levers, the joints being the fulcra. 
I. Bones in General 9 
II. Particular Bones.—Joints 15 
III. Injuries of Bones and Joints 25 
But levers alone are of no use. The bones form a strong 
framework for the body, but they can not move themselves. 
To produce motion, organs are required, which can become 
longer or shorter, under varying circumstances. Such organs 
are the muscles. 
IV. Muscles 29 GENERAL ANAL VS/S. 
Part III.—Organs of Repair. 
Energy is never lost or created. If the body loses energy 
in one way, it must gain it in another, or it will soon be worn 
out. Every muscular contraction wastes a certain amount of 
material, and an equal amount must be again supplied. This 
is done in the form of food. 
CHAPTER PAGE 
I. Food.—Supply and Waste 42 
But food, as it exists outside of the body, can not be 
appropriated by the wasting tissues. It must first be prepared. 
The process of preparation is called digestion. 
II. Mastication.—Swallowing 50 
III. Stomach-Digestion 57 
IV. Intestinal Digestion 79 
After the food has been so far prepared, it must in some 
way be carried through the body to all its different parts, that 
each may take what it requires for its sustenance. This is 
accomplished by means of a fluid which passes continually 
and rapidly through all parts of the body, carrying the nutri- 
tious material. This fluid is the blood. 
V. Tiie Blood 93 
But the blood, besides carrying nutriment, must also 
remove the waste and used-up matters, which injure the health 
if they remain in the body. There is also a gas, called oxygen, 
which is found to be necessary to the processes of nutrition. 
This gas exists in the air, and is taken from the air into the 
blood. The process, by which the blood gets rid of impurities 
and takes in oxygen, is called respiration. 
VI. Respiration 99 
VII. Asphyxia 120 
The blood can not visit the different parts of the body of its 
own accord. It is a fluid, and must be propelled. There are 
organs for this purpose, which keep up what is called the 
circulation of the blood. 
VIII. The Heart 125 
IX. The Blood-Vessels 136 
X. Disorders of Circulation.—Hemorrhage . .150 GENERAL ANALYSIS. 
Part IV.—Organs of Co-ordination. 
The motions of the body, the continual waste and supply, 
and the processes of digestion and circulation, form a very 
complicated series of phenomena. Certain parts of the body 
require more blood at certain times than at others. Processes 
taking place at the same time in different parts of the body 
might conflict and interfere with each other. We find, there- 
fore, a system of organs whose function it is to harmonize 
or co-ordinate all these processes, to produce a sympathy 
between them, and make them all work together for the com- 
mon interest. This is the nervous system. 
CHAPTER PAGE 
I. Nerve-Substance 164 
II. The Sympathetic System 174 
III. The Spinal Cord 183 
IV. The Brain 194 
V. Special Nerves.—Hygiene 208 
Part V.—Organs of Protection. 
All the organs previously described form a very delicate 
structure, which is continually exposed to external injurious 
influences. It is exposed to heat and cold, to blows and 
scratches, and all manner of violence, and so we find it en- 
wrapped in a strong covering, which protects it from these 
influences, partly by its own strength and toughness, and 
partly by certain organs which are imbedded in it, and form 
a part of it. This organ is the skin, with the various glands 
and other structures found therein. 
I. The Skin 217 
II. Functions and Care of the Skin .... 223 
Part VI.—Organs of Perception. 
The body being now complete, so far as its movements, 
nutrition, co-ordination of parts, and protection are concerned, 
we see that, as its food must come from outside, there must 
be organs to bring it into relation with the external world, to 
aid it in its search for food, and to protect it during the search. 
These organs are the organs of the senses, which bring us 
into relation with what is outside of us, and in this way are 
the sources of our ideas. The elementary one of these 
senses is touch, the others being only modifications of it. XII 
GENERAL ANALYSIS. 
CHAPTER PAGE 
I. Touch, Taste, Smell 237 
II. Hearing 246 
III. Sight 254 
Part VII.—Organ of Communication . . . .272 
The body being now practically complete, we find still 
another organ, whose function it is to enable us to communi- 
cate our ideas to others. This organ is the larynx, the organ 
of speech, that wonderful faculty which has had so much to 
do with creating the tremendous gap that exists between man 
and the lower animals. 
Part VIII.—Stimulants and Narcotics . . .277 
The body being thus fitted by its structure to maintain its 
integrity amid natural surroundings, is often subjected to arti- 
ficial conditions, which tend to cause disease and shorten life. 
In illustration of this may be cited the wide-spread use of 
stimulants and narcotics. 
Questions 307 
Glossary 323 
Index 337 PART I. 
IN TR OD UC TION. 
CHAPTER I. 
DEFINITIONS. 
l. Definitions.—The science which tells us about 
the different parts of the body, what they are, where 
they are, and how they look, is called anatomy. 
The science which tells us about the purpose of 
these parts, what they do and how they do it, is 
called physiology. 
The science which tells us what will interfere 
with the working- of these parts, what will injure 
and what will help them, and how to avoid what 
is hurtful, is called hygiene. 
A part of the body, which is so small that when 
it has been separated from other parts it can not be 
further subdivided without the destruction of its 
organization, is called an anatomical clement, as a 
cell or a fiber. 
Two or more anatomical elements, united or in- 
terwoven so as to form one substance, make what 
is called tissue ; e. g., fatty tissue, connective tissue, 
etc. 
A part of the body, which is made up of ana- 
tomical elements and tissues, together forming one INTRODUCTION. 
2 
whole, which can be separated from the rest of the 
body as an entire mass, and which performs a par- 
ticular function, is called an organ; as, the liver, 
the heart, a bone, or a muscle. 
A number of organs, similar in structure, but 
differing in size and shape, and spread throughout 
the body, are called a system; as, the nervous sys- 
tem, the arterial system, etc. 
Several organs, which differ in structure but 
are so connected as to work together for a particu- 
lar end, are called an apparatus; thus, the stomach, 
liver, etc., constitute together the digestive appa- 
ratus. 
The work that is done by a healthy organ in 
the body is called its function; e. g., the secretion 
of bile is a function of the liver. CHAPTER II. 
MINUTE STRUCTURE OF THE BODY. 
2. Minute Structure of the Body.—The body, 
when its parts are examined with the microscope, is 
found to be made up mainly of cells, fibers, and fluids. 
The cell is considered to be the original element 
out of which every other element in the body is 
formed ; fibers, fluids, etc., being derived from or 
generated by previously existing cells. 
The different consistency of different organs is 
due to the varying proportions of these elements. 
If the fibers are in the largest proportion, the tissue 
or organ will be hard, 
tough, and elastic ; if the 
cells form the greatest 
part, it will be soft, inelas- 
tic, and yielding. 
3. The Fiber. — The 
fiber proper (Fig. 1) is a 
slender thread, composed 
of a hard whitish or yel- 
lowish substance, some- 
times elastic and some- 
times not, but very tough 
and strong. Fibers are found in almost all parts of 
the body, binding the parts of organs together, and 
Fig. i.—Fibrous tissue. IN TROD UCTION. 
4 
constituting almost the entire mass of some parts, 
as the tendons or sinews, for instance. The word 
“ fiber ” is also used of certain portions of muscular 
and nervous tissue, in a different sense from the one 
given above. These differences will be explained 
hereafter. 
4. The Cell.—The cell is the most important 
structure in the living body, whether animal or 
vegetable. Life resides in the cell; and every 
plant or animal may really be looked upon as a 
mass composed of billions of cells, each of which 
is alive, and each of which has its own part to play 
in the nourishment of itself and the rest of the 
body. 
A single cell * (Figs. 2 and 3) is a portion of al- 
Fig. 2.—Epithelium from the mouth. 
Fig. 3.—Liver-cells. 
buminous matter, which has by some been called 
protoplasm,! sometimes surrounded by a thin mem- 
* Scrape gently the surface of the tongue, and put the fluid thus 
obtained under the microscope. Plenty of cells will then be seen, 
similar in appearance to those shown in Fig. 2. 
f Pro'toplasm, from two Greek words, signifying the first (or primi- 
tive) formed matter, because, so far as we know at present, it is the MINUTE STRUCTURE OF THE BODY. 
5 
brane and sometimes not, and usually having in its 
interior what looks like a smaller cell. This small 
body is called the nu'cleus of the larger one. In- 
side of the nucleus is often found another exceed- 
ingly minute body, or sometimes a mere shining 
point, called the nucle'olus (see Fig. 52). 
5. Protoplasm. — The protoplasm, or matter 
which forms the mass of a cell, is of a semi-fluid 
consistency, somewhat like jelly, and can not be dis- 
tinguished by chemical tests from albumen. Hence 
it is said to be albuminous in its nature, resembling 
to some extent the white of a raw egg, which is 
almost pure albumen. All cells are so exceedingly 
small, being rarely more than T0*0Tr of an inch in 
diameter, that we really know very little of their 
minute structure, on account of the difficulty of in- 
vestigating them with such imperfect instruments 
as we have. 
6. Granular Matter.—The points just mentioned 
are the most characteristic of the cell. Besides the 
cells, fibers, and fluids, there is a great deal of mat- 
ter in different parts of the body, which has been 
formed or deposited by the cells at different periods 
of their growth. This matter, under the micro- 
scope, sometimes appears granular, or as if made 
up of very minute specks, and sometimes almost 
transparent. Some of it is found to be fat in a 
finely-divided state, but some of it is albuminous, 
and some of it contains mineral matter in consider- 
able amount. 
7. Difference between Living and Dead Cells.— 
A living and a dead cell look precisely alike, except- 
simplest form of living matter, and makes up the only part of all ani- 
mal and vegetable bodies which shows signs of life. 6 
IA7 TROD UC TION. 
ing that the dead one is motionless. A living cell, 
minute as it is, frequently possesses the power of 
independent motion, or at least is able to change 
its form (Fig. 4). It also can take up nourishment 
into its mass, and can propagate itself. The move- 
ments of the cell can be 
beautifully seen in the 
white cells of the blood, 
which will be described 
hereafter. 
8. Growth of Cells.— 
A cell propagates itself in 
several ways; one of the 
most common is by divid- 
ing into two parts. This 
operation has been often 
watched under the micro- 
scope by skilled observers. The change is seen to 
begin in the nucleus, and, as that divides by a line 
through its center, the protoplasm of the cell ar- 
ranges itself in halves around each part of the nu- 
cleus, its surface dipping in toward the center, 
until finally the approaching surfaces meet and the 
Fig. 4.—White cells in motion. 
Fig. 5.—Cell dividing and forming two new cells. 
cell is divided into two new cells, each with its nu- 
cleus, and in every way complete (Fig. 5). This 
division goes on with great rapidity. The secre- 
tion from the throat and nose in nasal catarrh is 
composed mainly of cells, which are thrown off by 
millions during an inflammation. MINUTE STRUCTURE OF THE BODY. 
7 
g. Other Properties of Cells.—Cells also possess 
other powers which enable them to perform their 
important offices in the body. They are able to 
select certain substances out of a general mixture, 
and reject others. This is done by the liver-cells, 
for example, which secrete the bile, and by the cells 
of those glands which secrete the saliva. The cells 
of the brain act, in some unexplained way, as the 
instruments of thought. The cells in the kidneys 
separate matters from the blood which are very 
poisonous, and have to be expelled from the sys- 
tem. 
The power of division and of numerical increase 
of cells is not unlimited. If a portion of the body 
is wounded, it is healed again by the active efforts 
of the uninjured cells in the borders of the wound. 
The action of these cells ceases, however (if the part 
is healthy), to reproduce substance, when the part 
made vacant by the injury has been filled up. Why 
does this action of the cells, once started, not con- 
tinue until the body dies ? Why does the replace- 
ment of tissue cease as soon as the former surface 
is reached ? This question can not at present be 
answered.* 
Thus we see that the cell, minute as it is and 
simple as it is, performs its office in the body with 
* When the cells in the borders of a wound or sore are not in a 
healthy condition, they sometimes increase in number very rapidly, but 
the new cells, instead of being like the older ones, are larger, chiefly ow- 
ing to the greater amount of fluid in their interior. This makes them 
soft and spongy, and seems to interfere with their functions. They do 
not nourish themselves properly, and they increase and grow beyond 
the limit where they should stop, and where, if they were healthy, they 
would stop. This unhealthy growth is what is known as proud flesh, 
and it has to be repressed by proper surgical treatment. 8 
INTRODUCTION. 
care and evidence of forethought and intention. It 
does what is necessary and no more. It does not 
act blindly. It does all it does with a purpose. 
Where and what is the intelligence that directs the 
active living cell to repair so far and no farther, to 
eat this and reject that, to multiply up to a certain 
point and then stop, and, most wonderful of all, to 
take upon itself the duties of other cells when they 
are sick and unable to act,* and stop performing 
these extra duties, when the other cells recover? 
* When the kidneys, for instance, are diseased, so that the excretion 
of urine is interfered with, it is found that some of the poisonous mat- 
ters which usually pass out through them are ejected from the body 
through the lungs and skin. In such cases, physicians try to assist this 
process by inducing active perspiration, so as to relieve the kidneys 
from work as much as possible, and allow them to rest until they get 
well. PART II. 
ORGANS OF MOTION. 
CHAPTER I. 
BONES.—GENERAL STRUCTURE. 
10. Uses of the Bones.—If the body were com- 
posed merely of cells, such as have been described, 
with fibers and fluids, it would be a shapeless, jelly- 
like mass, incapable of locomotion, and of self-pro- 
tection. There is a necessity, in such a large mass, 
of points of support and resistance, and the organs 
or tissues which furnish such points must be tough, 
hard, and elastic. Such organs are the bones, which 
form the framework of the body and determine its 
shape and size. Their most important offices are 
two in number, viz., to act as levers and points of 
support and action for the muscular parts, and to 
protect the soft and delicate organs from external 
injury. 
11. Living and Dead Bone. — A bone, as we 
usually see it outside the body, is as different from 
a living bone as the skin of a corpse is from the liv- 
ing skin. We usually see it deprived of blood, 
while in the living body it is full of it, and is of a 
pinkish-white color externally, and deep red within. 
12. Composition of Bone.—To accomplish the ORGANS OF MOTION. 
10 
two purposes above mentioned, bones must be hard 
and tough, in order to maintain their stiffness when 
the muscles pull upon them, and also to be able to 
resist external blows. ’ They must also be in some 
degree elastic, or they would be too brittle for use, 
and would snap in two under great pressure. Ac- 
cordingly, we find all bones composed of two kinds 
of material, so thoroughly mingled and united that, 
when either kind is removed, the bone still retains 
its peculiar shape and size, although of course it 
does not weigh as much as before. About two 
thirds of the weight of every bone in the adult con- 
sists of earthy substances, mostly lime phosphate 
and lime carbonate, and the remaining third of ani- 
mal matter, part of which can be separated from 
the rest of the bone by long boiling, and is known 
as gelatine. 
If a bone be burned in a hot fire, all of the ani- 
mal matter will be destroyed, and the earthy mat- 
ters left. These will still retain the shape of the 
bone, but will be white in color, and will easily 
break and crumble in the fingers. If a bone, on 
the other hand, be soaked for a time in dilute hy- 
drochloric acid, all the earthy matter will be dis- 
solved out, and the animal portion left. This, as in 
the other case, will retain the shape of the bone, 
but will be flexible and tough, and may even be 
tied in a knot. 
By the combination of these two kinds of mat- 
ter, then, the bone is made hard, tough, and elastic, 
and admirably adapted to its uses in the body. 
13. The Composition of Bone varies with Age. 
—In infants and children, the amount of animal mat- 
ter in the bones is proportionately greater than in BONES.- GENERAL S TR UCTURE. 
11 
the adult, and so the bones of very young people 
will often bend when injured, instead of breaking. 
Surgeons call this the “ green-stick ” fracture, be- 
cause the bone is bent like a green twig, only a small 
portion of it on the outside of the bend being broken 
or torn apart. As a person grows older, the amount 
of earthy matter increases, until in old people the 
bones become very brittle, and break with very 
slight blows. 
14. Varieties of Bone and their Structure.— 
Bones are divided, according to their shape, into 
long bones, short bones, flat bones, and a fourth kind, 
called irregular, which combine qualities belonging 
to the other classes. The long bones are found only 
in the limbs, and are the most important to the sur- 
geon, as it is in them that most fractures and other 
injuries occur. They are divided into a shaft and 
extremities. The shaft of every long bone consists 
of hard, compact, closely-grained tissue, somewhat 
like ivory. This is the only part used in the man- 
ufacture of ornaments, buttons, knife-handles, etc. 
The extremities of these bones form the joints, and, 
in order to give greater security and a greater 
purchase to the muscles as well as a greater surface 
for their attachment, the ends are much larger than 
the shaft. The tissue of which they are composed 
is also not so hard and close in texture, as, if it were 
so, the bone would be too heavy. There is no finer 
example of economy of material and the combina- 
tion of strength with lightness than the structure 
of the long bones (Fig. 6). The ends are made of 
fine threads of bone interlaced and crossing and 
supporting each other, so as to make a sort of spongy 
tissue, full of little cavities, and yet very strong and ORGANS OF MOTION. 
12 
tough. And even the shaft of the bone is not solid, 
but, as every one knows, is hollow in the middle. 
This hollow space and the little 
cavities of the ends of the bone 
are filled with what is called 
marrow, a substance composed 
chiefly of blood-vessels and fat, 
which has important duties to 
perform in the growth and nour- 
ishment of the bone. The other 
varieties of bone are composed 
entirely of the spongy (or cancel- 
lous) tissue, with a thin layer of 
hard, compact tissue on the sur- 
face. 
15. The Periosteum and the 
Minute Structure of Bone.—All 
the bones are covered with a 
very tough, strong, fibrous mem- 
brane, called the perios'tcum, ex- 
cepting at the parts which enter 
into the formation of the joints, 
where they are covered with 
cartilage. This membrane ad- 
heres so closely to the bone as to 
require considerable force for 
its separation. It seems to form 
a part of the bone. Now, the 
periosteum and the marrow of 
the bones are necessary to their 
growth and nourishment. The 
blood-vessels and nerves spread and divide in these 
tissues before entering the actual substance of the 
bone. The bone itself is full of minute channels and 
Fig. 6.—The right femur, 
or thigh-bone, sawn in 
two lengthwise. Notice 
the arrangement of the 
bony fibers at the upper 
end, its peculiarity be- 
ing somewhat exagger- 
ated so as to make it 
more plain. BONES.—GENERAL STRUCTURE. 
13 
tubes varying in size from to the of an 
inch in diameter, through which the blood cir- 
culates, and the smallest of these tubes are con- 
nected at one end with exceedingly minute cavi- 
ties in the bone, in each of which lies a little cell, 
which does the work of nourishing, repairing, and 
enlarging the bone 
(Fig. 7). Thus we 
see that, even in so 
hard and firm a tis- 
sue as bone, what 
has been said about 
cells holds true. 
They are the real 
life of the bone; 
they separate from 
the blood the neces- 
sary material and 
deposit it around 
themselves, some- 
what as a crab re- 
news his shell eve- 
ry year after get- 
ting rid of the old 
one. 
16. Uses of the Periosteum.—It has long been 
known that, when the periosteum is severely bruised 
and separated from the bone by violence, the por- 
tion of bone deprived of the periosteum dies and 
has to be removed from the body. It is also found 
that a portion of bone, or even an entire bone, may 
be removed from the body, and if it be carefully 
done, so as to leave the periosteum in its place, the 
bone will grow again. A remarkable example of 
Fig. 7.—Cross-section of bone, magnified. 
The small black spots are the cavities in 
which the bone-cells live. The fine lines 
are canals through which the plasma (sec- 
tion 122) of the blood passes. The large 
holes are for blood-vessels. 14 
ORGANS OF MOTION. 
this was a case operated upon by the late Dr. James 
R. Wood, of New York. In a young woman, whose 
lower jawbone had become dead and caused her 
great suffering, this distinguished surgeon removed 
the whole jaw, leaving the periosteum and even the 
teeth, held in their places by an apparatus made for 
the purpose. The entire bone grew again, and the 
teeth became fixed in it as it grew. The person 
died several years afterward, and her skull, show- 
ing the result of this wonderful operation, is in the 
museum at Bellevue Hospital.* 
* Other experiments have even shown that, if a piece ot fresh living 
periosteum be transplanted from a bone to a muscle, it will produce 
bone in its new situation. These remarkable qualities of the perios- 
teum have been explained by some, by supposing that, in each case of 
operation or experiment, some of the minute bone-cells have adhered 
to the periosteum when the mass of the bone was removed, and that 
they were the chief agents in forming the new bone. CHAPTER II. 
NUMBER OF BONES.—PARTICULAR BONES.—JOINTS. 
17. The number of bones in the human body is 
two hundred (Fig-. 8). At one period of life they 
are nearly all cartilaginous, but the cartilage is grad- 
ually changed into bone. This process of change, 
ossification, as it is called, is not complete before the 
twenty-fifth year of life, and therefore no person 
can be called really grown up until that time. 
18. The Vertebrae.:—The foundation, so to speak, 
of the body—that portion of the skeleton to which 
the remainder is attached, and from which it is 
built up—is the spine, or backbone (Fig. 9). This 
is composed of many small bones, all of the same 
general pattern, called ver'tebrce. The principal part 
of the vertebra (Fig. 10), called the body, is shaped 
very much like a wooden pill-box slightly hollowed 
out on the top and bottom. The bodies of the ver- 
tebrae form the front of the spinal column. From 
the rear of each of these bodies are offshoots of 
bone, which unite in such a way as to leave a hole 
about half an inch in diameter running up and 
down. These vertebrae are placed one above an- 
other, with elastic pads of cartilage between their 
bodies. These pads are so thick that, taken all to- 
gether, they make up about one fourth of the whole 16 
ORGANS OF MOTION. 
Fig. 8. —The skeleton. THE SPINE. 
length of the backbone. The vertebrae being ap- 
plied to each other in this way, it is evident that 
the holes just mentioned, which 
are surrounded by bone, will form 
a continuous canal (the spinal ca- 
nal) running from the skull down 
the back. This canal contains 
the spinal cord, which, next to the 
brain, is the most important part 
of the nervous system. At the 
sides of the spine, throughout its 
whole length, are holes, out of 
which pass nerves supplying the 
muscles and other organs of the 
body, and into which pass the 
blood-vessels that nourish the 
spinal cord. 
19. The Spine. — The back- 
bone, being composed of so many 
pieces, is very movable. The 
power of motion varies, however, 
in different parts. It is greatest 
in the neck, and least in that por- 
tion of the back to which the ribs 
are attached. In the human be- 
ing, the neck is not so flexible 
as in many animals. Birds, in 
particular, can look directly back- 
ward. 
Notwithstanding the great 
power of motion in the spine, the 
different bones are very strongly 
united and protected by power- 
ful ligaments and muscles, which 
Fig. 9.—The spine, sawn 
in two lengthwise, 
showing the spinal 
canal and the holes 
between the verte- 
brae, where nerves and 
blood-vessels pass out. ORGANS OF MOTION. 
render it difficult for a vertebra to slip out of place, 
and such an accident is one of the rarest which a 
surgeon is ever called upon to treat. 
Fig. io.—A vertebra. 
The elastic pads between the vertebrae deaden all 
shocks of the body and prevent them from injuring 
the brain. These pads become compressed during 
the day, especially when a person is much on his 
feet, so that at night-time the body is from one 
quarter to one half an inch shorter than it is in the 
morning. During sleep or rest the elasticity of the 
pads causes them to resume their original shape 
and thickness. 
20. The Skull.—The skull is the only portion of 
the skeleton whose principal office is the protec- 
tion of soft parts within it. Accordingly, we find SUTURES OF THE SKULL. 
19 
that its bones are differently composed and dif- 
ferently put together from the other bones in the 
body. Those forming the outside of the skull, im- 
mediately surrounding the brain, and most exposed 
to blows, are composed of three layers. The out- 
side layer is the thickest, and is tough and some- 
what elastic. The innermost layer is very thin, but 
hard and brittle, so that it is called the vit'reous 
(glassy) table of the skull. Between these layers is 
spongy tissue, like what has been before described. 
This deadens every blow upon the head, and the 
safety of the brain is still further provided for by 
the arched shape of the skull, which tends to dif- 
fuse the force of a blow. The protection afforded 
by the shape and structure of the outside por- 
tion of the skull is very great, and it is a well- 
known fact in surgery that a blow upon the top 
of the head, without breaking the bone on which 
it falls, may break the bones at the base of the 
skull, immediately opposite the spot of the blow, 
by the mere force of the shock, although the latter 
bones are much thicker and more massive than the 
others. 
There is only one movable bone in the skull and 
that is the lower jaw. If the upper jaw be made to 
move in eating or speaking, it is only by moving 
the whole head where it joins the neck. 
21. Sutures of the Skull.—The bones of the 
skull are joined together by what are called sutures 
—i. e., their edges are jagged and irregular, and fit 
together like dovetailed boards (Fig. n). This 
renders the arch of the skull more compact, and, 
as far as resistance to pressure is concerned, the 
bones might be considered as one piece, while the 20 
ORGANS OF MOTION. 
interruptions at the sutures tend to deaden the 
shock of a blow. 
22. The Frontal Sinuses.—In the front of the 
skull there; are two 
cavities in the sub- 
stance of the bone 
itself. These are 
situated just above 
the eye-brows, and 
are called the fron- 
tal si'nuses (Fig. 12). 
The layer of bone 
which forms their 
front wall causes 
the prominences 
just over the eye- 
brows, and, as the cavities increase in size with 
age, this portion of the forehead becomes more 
prominent. The cavities are lined with mucous 
membrane, and are 
connected with the in- 
side of the nose by a 
canal or small passage, 
so that, when a person 
has a severe cold in 
the head, the inflam- 
mationsometimesruns 
up this passage into 
the frontal sinuses. 
When this is the case, 
the person has a dull, 
stuffy headache in that 
locality, due to the swelling of the mucous membrane. 
2% The Ribs.—The bony part of the walls of 
Fig. ii.—General outlines of the skull, show- 
ing the sutures. 
Fig. 12.—Frontal sinus. NATURAL SHAPE OF THE CHEST. 
21 
the chest is made up of tiventy-four ribs and the 
breast-bone, together with part of the spine behind. 
There are twelve ribs on each side, the first, nearest 
the neck, being usually the shortest. They increase 
in length from the first to the seventh, and then di- 
minish, so that the twelfth is also quite short. They 
are flat and narrow, and are attached at one end to 
the spine, in such a manner that they move easily 
up and down, while the other end is attached to the 
breastbone, or sternum, bv means of a piece of car- 
tilage, varying in length with the length of the rib. 
The eleventh and twelfth ribs are not attached to 
anything at their forward end, and hence are called 
floating ribs. 
The ribs are attached to the spine in such a way 
that all of them move together up and down. In 
front, the stiff but elastic cartilage allows motion in 
every direction. Now the shape of the ribs is so 
peculiar, being a sort of double curve, that when 
they are raised at the sides, the ends which join the 
breastbone are pushed forward, and of course carry 
the breastbone with them. So it is evident that at 
every inspiration the diameter of the chest increases 
from front to rear as well as from side to side. 
24. Natural Shape of the Chest.—In young peo- 
ple the cartilages are soft, but they grow harder as 
age advances, and become partially turned into 
bone. In youth they yield to pressure to such an 
extent that by tight lacing the shape of the chest is 
sometimes made exactly the reverse of what it ought 
to be (Fig. 13). The ribs naturally form a cone, with 
the smaller end uppermost, but it is not uncom- 
mon to see the smaller end at the waist. Na- 
ture will endure a great deal of meddling, but it 22 
ORGANS OF MOTION. 
is not always safe to trifle with her, and all persons 
who carry tight lacing too far will inevitably suffer. 
Fig. 13.—A represents the normal appearance of the ribs. B represents part of a photograph of 
the skeleton of a young woman of twenty-three years, showing the distortion of the ribs pro- 
duced by tight lacing in an actual case. 
25. The Limbs.—More than one half of the 
bones in the body are found in the limbs. Out of two 
hundred bones, they contain one hundred and twen- 
ty-six, and these are so constructed and so arranged 
as to afford a great variety of movement. The up- THE JOINTS. 
23 
per and lower limbs are what is called homologous 
in their parts—i. e., each bone in the arm has its 
counterpart in the leg, with only slight apparent 
exceptions. Thus, 
the shoulder-blade 
corresponds to the 
body of the hip-bone, 
the collar-bone to the 
front of the hip, the 
arms to the thigh, 
the two bones of the 
fore-arm to the two 
of the leg, the wrist 
to the ankle, and the 
hand and fingers to 
the foot and toes. 
The similarity and 
correspondence of 
these parts are quite 
clear in the skeleton. 
26. The Joints.— 
To render move- 
ments possible, the 
skeleton is broken up 
in its whole extent 
by numerous joints. 
The surfaces of the 
joint are not covered 
by periosteum, but 
by a firm, bluish- 
white, smooth, and 
very elastic sub- 
stance called carti- 
lage. The two cartilage-covered surfaces in every 
Fig. 14.—The right knee-joint, showing how 
strongly it is bound about by ligaments. ORGANS OF MOTION. 
24 
joint are in contact with each other. The joint is 
closed entirely by the syno'vial membrane, which 
passes over from one bone to the other, all round 
the outside. This membrane is exceedingly smooth 
and delicate, and its inner surface exudes a fluid very 
much like the white of an egg, which moistens the 
surface of the joint and renders every movement 
easy and frictionless. Outside of these structures 
are ligaments (Fig. 14), which hold the bones firmly 
in their places. Ligaments a're composed of white, 
fibrous tissue (Fig. 1)—i. e., of tough, inelastic fibers 
or threads running parallel with each other, of a 
shining, silvery-white color. They are flexible, so 
as to allow of considerable lateral movement, but 
are tough and exceedingly strong, so that they hold 
the ends of the bones close together. Thus, the 
construction of the joints is such that they are 
strong, flexible, elastic, and supple. CHAPTER III. 
INJURIES OF BONES AND JOINTS. 
27. Inj'uries in General.—The injuries to which 
the bones are most liable are fractures and disloca- 
tions. If the bone be fractured, the jagged ends of 
the broken bone irritate the parts about them, and 
the muscles contracting pull the broken ends out of 
their proper relation to each other (Fig. 15). In the 
dislocation, the end of the bone is out of its proper 
place. But the limb is movable at the point of fract- 
ure, while it is always stiff and fixed at the point 
of dislocation. In a fracture, also, the ends of the 
bone, if gently moved against each other, produce 
a peculiar grating feeling, which always tells the 
surgeon with certainty that the limb is broken. 
28. Fractures.—Bones are rarely broken straight 
across, excepting in very young persons. The fract- 
ure is usually oblique, and so the broken ends slide 
past each other, and the limb is shorter than it was 
before the accident. In a.broken thigh, the bone is 
surrounded by such a thick mass of muscles that, 
even if the broken ends are pulled by force into 
their proper places, it is impossible to keep them 
there. They will always slide past each other to a 
slight extent, and a person never recovers from such 
an accident, without having the injured limb from 26 
ORGANS OF MOTION. 
half an inch to an inch shorter than the sound one. 
This has been shown and proved by thousands of 
careful measurements, 
and should always be 
borne in mind when 
there is a temptation to 
blame a surgeon for fan- 
cied neglect. 
When a fracture oc- 
curs near a joint it is a 
much more serious ac- 
cident, for the inflam- 
mation which follows 
the injury involves the 
parts about the joint, 
and sometimes the joint 
itself, which maybe left 
stiff and almost useless 
for a long time after- 
ward. This is particu- 
larly the case with frac- 
tures near the wrist, for the slow recovery of which 
the surgeon is so often blamed. 
29. Dislocations. — When a bone is dislocated 
there is always a certain amount of injury to the 
parts about the joint. The ends of the bone are so 
carefully and strongly guarded and fastened by lig- 
aments and muscles, that these must necessarily be 
considerably torn and bruised, in order to let the 
bone out of its place. Thus it happens that a dis- 
location often gives rise to more pain and suffering 
immediately after the accident than a fracture.* 
Fig. 15.—Fractured humerus, showing 
how the muscles pull the ends of the 
broken bone out of place. 
* Sometimes the violence resulting from a fall is not sufficient either 
to break or dislocate a hone, and yet the parts about a joint are so se- INJURIES OF BONES AND JOINTS. 
27 
The vast majority of dislocations occur in the 
shoulder and hip joints, and are usually caused by 
a blow on the end of the bone when the limb is 
firmly extended, as when a person is falling and tries 
to save himself by stretching out his hand. The 
lower jaw is sometimes dislocated, and then the 
mouth remains wide open until the dislocation is 
reduced, rendering the sufferer a somewhat ludi- 
crous as well as pitiable sight. This accident has 
been known to occur during a prolonged yawn. 
30. Healing of Injured Bones.—A fractured bone 
takes from three to six weeks, and sometimes longer, 
to become healed. A dislocated bone, after it is re- 
duced, requires to be kept quiet until all pain and 
swelling have subsided. In either case, there always 
remains more or less stiffness, which sometimes 
does not disappear for months after the accident. 
31. Care of Injured Persons.—It frequently hap- 
pens that a bone is broken when the person is at a 
distance from his home, or from any place where 
he can be attended by a surgeon. In fractures of 
the lower limbs, he must be carried often for a long 
distance, and every one should know how to make 
him comfortable during transit. It must be remem- 
bered that the only object of any person who is not 
a surgeon, should be to keep the broken limb in 
such a position that there will be no motion of the 
fractured ends, so that the patient may suffer as 
little as possible, and the surgeon may find him as 
nearly as may be in the condition in which the in- 
verely strained that some of the ligaments are tom apart. Very often 
only a few fibers are ruptured, but such injuries always cause great suf- 
fering, and recovery is very slow. This form of injury is called a 
sprain, arid is most likely to occur in the wrist, ankle, or knee. 28 
ORGANS OF MOTION. 
jury left him.* Therefore, he should be carried on 
a litter, the broken limb being packed about with 
soft materials in such a way as to keep it from roll- 
ing or jarring. The weight of the foot will often 
make the lower part of the leg swing from side to 
side, and in the case of a fractured thigh, the leg 
should be protected on each side from the hip 
down. Dislocations require the same care, except- 
ing that a splint is not necessary. 
* It is a very good plan to bind the lower limbs together in such a 
case, above and below the injured part, so that the sound leg may serve 
as a splint to the broken one. A broken arm may be bound to an im- 
provised splint (a cane, a stick of wood, a shingle), a folded handker- 
chief or other padding being used to fill up the hollows between the 
splint and the skin, and the broken limb being supported by a sling 
around the neck. CHAPTER IV. 
MUSCLES. 
32. The Muscles.—The bony framework of the 
body is set in motion by a system of organs called 
muscles, which cover the skeleton almost entirely 
(Fig. A), and cause the different bones to move 
upon each other by means of their peculiar prop- 
erty of contractility, or the power of becoming 
longer or shorter under varying circumstances. 
There are two kinds of muscles in the body, 
called voluntary and involuntary, which differ very 
much in their structure and functions. The volun- 
tary muscles, as the name implies, are under the con- 
trol of the will; while the involuntary muscles are 
not only beyond our control, but act as a rule with- 
out our knowledge or consciousness. 
33. The Voluntary Muscles.—A voluntary muscle 
is a mass of reddish fibers, somewhat loosely joined 
together by connective tissue, and easily separated 
lengthwise.* The flesh of animals is composed of 
muscular tissue. Every voluntary muscle is united 
* If the fibers of a piece of lean meat are carefully separated and 
closely scrutinized, it will be seen that they are connected with each 
other by a delicate tissue of fine white threads, interwoven like the 
fibers of a cobweb or of the most delicate lace-work. This is called 
connective tissue, and is found in almost all parts of the body, uniting 
the different elements that make up the various organs. ORGANS OF MOTION. 
30 
Fig. A.—The muscular system. THE MUSCLES. 
at each end to some fixed point in the body, and 
there is always a joint or point of flexure between 
its points of attachment. When the muscle con- 
tracts, therefore, the two ends are brought nearer 
together, and motion is produced in the organ or 
limb to which it is attached. 
Every voluntary muscle can be divided into 
small fibers, lying side by side, and these again into 
fibrils still more minute. Each fibril under the 
microscope presents an appearance of delicate lines 
running at right angles to its length (Fig. 16). 
Fig. 16.—Voluntary muscular tissue. 
These lines are called stricz, and the appearance is 
called striation. 
34. The Involuntary Muscles.—Involuntary mus- 
cles are made up of flattish bands of long-, narrow 
fibers, tapering at each end, somewhat of the shape 
of an oat, but more slender. Each fiber has a nu- 
cleus in its middle, and they are ail connected 32 
ORGANS OF MOTION. 
together lengthwise, as the voluntary muscular 
fibers are (Fig. 17). 
35. Differences between the Voluntary and In- 
voluntary Muscles.—The voluntary muscles are all 
composed of the striated muscular 
fiber which allows of very rapid 
contraction, while the involuntary 
muscular fibers contract in a very 
peculiar manner. They do not be- 
gin to contract immediately, as 
soon as they are stimulated, but 
there is a short interval between 
the irritation and the response of 
the muscle. Then the contraction 
begins, and proceeds slowly and 
continuously up to a certain de- 
gree, when the fibers slowly relax, 
very much like the slow, crawling 
motion along the body of a worm 
or snake, when a wave seems to 
travel from one end to the other. 
Now there are some organs in the 
body, whose action must be rapid, from the nature 
of the office they perform, and still it would not do 
to have their motions depend upon the will. Such 
an organ is the heart. It must contract often and 
quickly in order to supply sufficient blood to the 
body, and yet, if its action depended upon our will, 
it would require all of our attention, to the exclu- 
sion of everything else. Accordingly, we find it 
composed of muscular fibers that are intermediate 
in structure between the voluntary and involuntary 
kinds. The involuntary muscular fiber is found, 
among other places, in the stomach and intestines, 
Fig. 17.—Involuntary 
muscular tissue. THE MUSCLES. 
33 
in the iris of the eye, and in the walls of the ar- 
teries. 
36. Difference in Size of Muscles.—The largest 
muscle'of the back, the latissimus dorsi, weighs sev- 
eral pounds; and one of the muscles of the leg, the 
sartorius, is two feet long ; while the stapedius, one of 
the little muscles inside the ear, is only the sixth of 
an inch long, and weighs about a grain.* Between 
these extremes are many variations in size and 
shape. 
37. The Tendons.—Muscles are connected with 
the bones by means of tendons. A tendon is made 
up of fibrous tissue, and is a white, glistening cord, 
of exceeding strength and toughness. At the ends, 
they gradually change their appearance, becoming 
muscle at one extremity and bone or periosteum 
at the other. There is no sharp line, where the 
muscle or bone can be distinguished from the ten- 
don. Wherever the tendons would be likely to rise 
and form a line like the string of a bow during the 
contraction of a muscle, as at the wrist and the 
* Lads'simus dorsi—i. e., the broadest of the back. This muscle is 
attached to the spine in the lumbar region and also to the lower ribs. 
The fibers come together so that the muscle has a triangular shape, and 
its small end is attached to the humerus. It is the chief muscle that 
comes in play when the body is raised from the ground by means of the 
arms. 
The sarto’tius means the tailor's muscle. It is a long, ribbon-like 
muscle, which begins on the outside of the hip-bone and ends on the 
inside of the knee, crossing the thigh on the inner side. When it con- 
tracts, it raises the lower part of the leg, and turns it inward, thus 
crossing the legs, tailor-fashion—hence its name. It comes in play 
when one foot is placed on the opposite knee. 
Stape'dius means the stirrup-muscle, so-called because it is attached 
to a small bone in the ear, which is shaped like a stirrup, and hence 
called sta'pes (Latin for stirrup). r 34 
ORGANS OF MOTION. 
ankle, for example, they are bound down by stout 
ligaments, through or under which they slide to and 
fro, the channels in which they move being lined 
with synovial membrane like the joints. 
38. Force of Muscular Contraction. — When a 
muscle contracts (whether voluntary or involuntary), 
it becomes not only shorter and thicker, but harder, 
than before, and the force with which it contracts 
is enormous. To attain the compactness which we 
see in the body, the muscles of the limbs, for ex- 
ample, have to lie parallel with the length of the 
limb. Besides this, many of them are attached be- 
tween the fulcrum and the weight, and very near 
the fulcrum. The biceps, for instance, which (with 
the brachialis anticus) bends the forearm upon the 
arm, is attached at one extremity to the shoulder- 
blade, and at the other to the forearm, just below 
the elbow, where its tendon can be felt. Thus there 
are two disadvantages under which it acts. In the 
first place, its point of action is only about one eighth 
as far from the joint or fulcrum as the hand is, and 
in the second place, when it begins to contract, it 
acts at a very acute angle—in fact, almost parallel 
with the bone (Fig. 18). As the arm becomes flexed, 
Fig. 18.—Disadvantageous action of the biceps muscle, 
illustrated. 
the angle of action approaches -more and more to a 
right angle, and the necessary effort becomes less THE MUSCLES. 
35 
and less. And yet we not only flex the arm easily 
enough at the elbow, but we do it with a consider- 
able weight in the hand. It has been estimated that 
the muscles of the arm, in flexing it at the elbow, 
with a ten-pound weight in the hand, contract with 
a force of at least two hundred pounds. And yet 
this is a feat which a delicate woman or a child can 
perform, and the force required is not to be com- 
pared with the power of an athlete. 
39. Muscular Irritability. — Muscular tissue will 
contract under any kind of irritation. In the living 
body, the stimulus always comes from the nerves, 
but the muscle itself has a form of irritability, which 
lasts for a considerable time after death. When an 
ox is killed, and has been prepared for the market, 
the muscles may often be seen twitching and quiver- 
ing in the beef for half an hour, and the muscles of 
an amputated arm may also be seen to contract for 
some minutes merely under the irritation of the cold 
air. In cold-blooded animals, this irritability persists 
for a long time. If the heart of a frog be entirely 
removed from the body, it will continue to beat for 
several minutes, and, when it has finally ceased, it 
will start again on being pricked with a needle. 
This experiment may be repeated several times be- 
fore the muscular irritability finally vanishes.* 
40. The Muscular Sense.—When a muscle con- 
tracts, the degree of contraction is perceived or felt 
* There are reasons for believing that the continued beating of the 
heart of a cold-blooded animal for hours after it has been removed 
from the body may be due to the presence of microscopic nervous 
ganglia in the substance of the muscle. This supposition, however, 
does not affect the usefulness of the frog’s heart as an illustration of 
the fact that parts of animals continue to live after separation from the 
main body. 36 
ORGANS OF MOTION. 
by the brain. For example, any one is conscious 
whether his thumb is bent inward toward the hand, 
or outward toward the wrist, entirely apart from 
the use of the sight. The precise manner in which 
this sensation is conveyed to the brain is still a sub- 
ject of conjecture. Although apparently so simple, 
it brings up questions of great intricacy and dif- 
ficulty, which can not be considered here. But this 
sense, whatever its manner of operation, is called the 
muscular sense. It is one of the chief means we have 
of determining the weight or the hardness and soft- 
ness of bodies, as we judge of these qualities mainly 
by the resistance our muscles meet with when hand- 
ling the bodies. But, more than all, the muscular 
sense is necessary in keeping the body upright. The 
size of the feet is so small, compared with the height 
of the body, that early in life it is a matter of ex- 
treme difficulty for us to keep our balance. To 
stand and walk is one of the first and one of the 
hardest things we have to learn. It requires a con- 
stant contraction of the muscles, now one set and 
now another, in order to keep from falling. 
41. Use of the Muscular Sense in Standing.— 
Ordinarily we are assisted in standing upright by our 
sight. This fact, together with the muscular effort 
required to stand still, may both be made very evi- 
dent in the following manner: if a person stands 
with the feet close together, he will perhaps feel a 
slight swaying of the body, which has to be counter- 
acted by muscular contraction. Perhaps no such 
swaying will be perceptible to him. But now, still 
keeping the feet close together, let him shut the 
eyes, when the swaying of the body will become 
much greater than before, and the constant muscular THE MUSCLES. 
37 
contractions, now here, now there, will be so plainly- 
felt as to be disagreeable. In certain diseases, this 
muscular sense in the legs is lost, and then the per- 
son can stand with the eyes open, but if the eyes be 
closed he instantly totters and falls, for he then has 
nothing to guide him as to his vertical position. 
42. Waste during Muscular Contraction.—The 
cause of muscular contraction is an unsolved prob- 
lem. There is nothing in the chemical composition 
or the physical structure of the muscle which would 
lead us to expect to see it contract when irritated, 
if we knew nothing more about it. All we can say 
is, that it depends upon the composition of the mus- 
cular substance, and we know, also, that every con- 
traction is accompanied by a loss of or change of 
material. In this way, our muscles are being con- 
tinually used up, and if they were not constantly sup- 
plied with fresh nourishment by the blood, they 
would soon wear out and die. But the minute mus- 
cular fibers (or the cells composing them) not only 
perform their special function of contraction, but 
are able to choose and take up out of the blood their 
own proper food and appropriate it. 
43. Muscular Overwork.—If a muscle is hard 
pressed and exercised too much, so that the waste 
of material is greater than the supply, and it wears 
away faster than it is repaired, it falls into the con- 
dition which we call fatigue, and it is only with 
great effort that we can make it work. If it be still 
further imposed on, without opportunity to recu- 
perate, it soon gives out entirely, and can not be 
made to contract with vigor under any stimulus our 
brain can send to it. Such extreme fatigue is dan- 
gerous, because there is always the chance that the 38 
ORGANS OF MOTION. 
muscular fibers may become so completely wasted 
that even their power of nourishing themselves may 
be impaired, and the recovery of their natural con- 
dition may be very slow and imperfect, or, in rare 
cases, impossible. 
44. Muscular Inactivity.—On the other hand, if a 
muscle is not exercised at all, its power of nourish- 
ing itself is interfered with almost as much as if it is 
exercised too much. It is found that unused mus- 
cles gradually waste away, growing smaller and 
smaller, and becoming soft and flabby, and finally, if 
they are not used for a very long time, it can be seen 
by the microscope that the muscular fibers disappear 
altogether, or are filled with little particles of fat, 
which take the place of some of the muscular sub- 
stance, and so make it very weak and useless. Such 
inactivity of the muscles may occur in cases of paral- 
ysis, and the physician is then careful to stimulate 
them with electricity, in order to keep them, as 
nearly as possible, in a sound condition. The elec- 
trical current, in such cases, takes the place of the 
nervous stimulus, which naturally causes muscular 
contraction. The muscles of a broken limb, also, 
which have necessarily been idle while the bone was 
mending, are always very feeble for some time after 
the limb comes in use again.* 
* Curvature of the spine, which is more frequent among girls than 
among boys, is often directly attributable to lack of exercise. The 
muscles of the back become weak, and, as some exercise of the muscles 
of the right side can not be avoided, so long as the girl performs any 
duties whatever, the difference in strength between the muscles of the 
right side and those of the left side becomes greater than is natural. 
The result of this is that the stronger muscles overpower the others and 
pull the spine over toward the right side, greatly distorting the figure. 
In left-handed persons the curvature is toward the left side. EXERCISE. 
39 
45. Exercise.—It is necessary, therefore, that the 
muscles should be sufficiently exercised, and not too 
much. The kind of exercise is not of so much im- 
portance. No better form of exercise can be de- 
vised than the various out-door sports that boys are 
so fond of. It is much better that exercise should 
be a pleasure than a duty. For this reason, the or- 
dinary exercises of the gymnasium do not compare 
in value, as health-giving ones, with rowing, skating, 
running, riding, wrestling, swimming, and the va- 
rious out-door games.* It is really of no advantage, 
in our ordinary modern life, that the upper arm 
should, by judiciously and ingeniously planned ex- 
ercise, grow to be an inch larger than it was a year 
before, and to the ordinary youth the duties of a 
gymnasium are irksome to the last degree.f There 
is no evidence that athletes, whose bodies are 
knobbed with unsightly bunches of muscle, are any 
healthier or any happier, or live any longer, or do 
any more good in the world, than the less muscular 
* These remarks apply to girls as well as to boys. Out-door exer- 
cise of an agreeable kind is as necessary for the health of one as of the 
other. The hot-house plant is never strong, and the tom-boy grows to 
be the most healthy and vigorous woman, both mentally and physically. 
f It is not to be understood that the gymnasium is here altogether 
condemned. It is of great use in its proper sphere. But the boy’s idea 
of a gymnasium is that it is a place to get strong, rather than healthy. 
The surroundings and examples are such as to encourage straining for 
effect, lifting heavy weights in emulation, and the like acts, which may 
injure a boy permanently. When gymnastic exercises are performed 
under a competent instructor, with proper ends in view, and an intelli- 
gent use of means to those ends, the matter is altogether different. 
But, as mentioned in the text, gymnastic exercises, excepting for the 
purpose of remedying particular defects, training special muscles for a 
particular purpose, or treating actual disease, can not be compared in 
efficiency with out-door sports. 40 
ORGANS OF MOTION. 
person who confines himself to simple food, who in- 
sists upon pure air, and exercises moderately and for 
his own pleasure in the way that suits him best.* 
46. Danger of Exhaustion.—But, while muscular 
exercise is necessary to continued good health, it 
should never be carried to the point of exhaustion. 
This is dangerous, not only, as previously indicated, 
because the nutrition of the muscle may thus be in- 
terfered with, but because, when the point of simple 
fatigue is passed, and exhaustion supervenes, the 
nervous system has become implicated and is getting 
worn out. This danger will be better understood 
when that part of our bodies is described hereafter. 
It is enough, for the present, to remember that a 
person is not harmed by being tired, but that it always 
harms one to be exhausted. 
47. Rest.—When a muscle is fatigued, it recov- 
ers very fast if allowed to rest. For this reason 
it is much less fatiguing to walk an hour than to 
* The muscular strength which is developed by gymnastic training 
vanishes when the training ceases. It is often noticed by those who 
practice much in gymnasiums that constant practice is necessary to re- 
tain what increase of muscular power they have acquired. There seems 
to be a normal condition of the muscular system in each individual, to 
which he reverts when special training is abandoned. The strong men 
are not made so by training ; they are born with a tendency to a pre- 
ponderance of the muscular organs. Marvelous stories are told of 
men of this class. It is said of Frederick Augustus of Saxony, King 
of Poland (1670-1733), commonly called Augustus the Strong, that on 
one occasion, wishing to present a bouquet to a lady, and seeing nothing 
to wrap it in, he took a silver plate from the table and folded it around 
the stems with the greatest ease. In Dresden is exhibited a horseshoe, 
or the halves of it, which he is said to have broken with one hand. 
Similar stories are told of Baron Trenck (1711-1747); and of Milo, of 
Crotona, a famous athlete (520 B. c.), it is said that he once carried a 
live ox on his shoulders around the stadium, then killed it with a blow 
of his fist, and afterward ate the whole of it in a single day. EXERCISE. 
41 
stand still an hour. In the former case the muscles 
constantly have short intervals of rest, while in the 
latter they are not able to rest at all, but are con- 
tinually in a state of contraction. If we are obliged 
to stand for a long time, therefore, we almost instinct- 
ively change our position frequently, stand on one 
leg and then on the other, or find some place to 
lean against, in order to give the muscles the rest 
they need. 
Out-door sports, then, are more healthful than gym- 
nastic exercises. 
Exercise may be pushed to the point of fatigue with- 
out injury, but never to the point of exhaustion-. PART III. 
ORGANS OF REPAIR. 
CHAPTER I. 
FOOD. 
48. Necessity of Food.—We all know that, as 
long as we are living beings, we tend constantly to 
lose weight. In our excretions, our breath, the per- 
spiration, the tears, the saliva, we lose altogether 
several pounds a day. All of this matter is so much 
gone, and if it be not replaced the body dies. It 
can not be too clearly impressed upon the mind 
that this waste or loss of material is continuous 
and inevitable. The processes of muscular contrac- 
tion, of secretion, even of thought, produce sub- 
stances which are taken up by the blood to be put 
out of the body. These substances are, many of 
them, very poisonous, and if they can not be ex- 
pelled from the body they kill it.* They are not 
the result of disease ; they are the constant product 
of living processes in a healthy body. So we see 
* Thus certain waste matters are excreted from the body through 
the kidneys. Some of them are very poisonous, and, when the kidneys 
are diseased and are no longer able to discharge them all from the body, 
they accumulate in the blood and finally cause death. So it is with the 
bile and with certain matters which pass away in the breath at every 
respiration. FOOD. 
43 
that there must be a continuous expulsion of such 
matters, and, of course, what each part of the body 
has lost by such a process must be replaced with 
fresh material. 
49. Living without Food impossible.—If this fact 
be clearly understood, it will be easy to see that the 
numerous stories about persons who live without 
eating are false. If such persons live, their hearts 
must beat, their brains must think, their lungs must 
move in breathing, and all of these things cause in- 
evitably a waste of material. How absurd, then, to 
gravely talk of a person who has not taken any 
food or drink for six months, and still has not lost 
weight, but remains plump and healthy ! It is just 
as absurd as it would be to say that such or such a 
person had a limb amputated day after day, and yet 
after each operation weighed as much as before. 
These cases are all cheats, for if there is waste going 
on, which is not made good, the body must decrease 
in weight. If there is no waste, there is no life, no 
thought, no heart-beats, no respiration, no move- 
ment of any kind. These facts of the generation of 
force by food and of constant loss and gain are the 
chief foundation-stones of all correct knowledge of 
physiology, and can not be too firmly fixed in the 
mind. 
50. Classification of Food.—In order to supply 
the waste in our bodies we need a great variety of 
food; and, indeed, the procuring and preparing of 
food occupy a large portion of the lives of most peo- 
ple. The food we use is usually classified as nitroge- 
nous and non-nitrogenous, or carbonaceous. But, besides 
these two great divisions, which include all our ani- 
mal and vegetable food, there are some substances 44 
ORGANS OF REPAIR. 
which are neither animal nor vegetable, and yet are 
quite as necessary to our health as any other por- 
tion of what we eat. The most important of these 
are water and salt. 
51. Water.— Water is present in a greater or less 
quantity in every part of the body, and, as it is rap- 
idly expelled, it has to be frequently supplied. It 
constitutes between three fourths and two thirds of 
the entire weight of the body, and the amount re- 
quired for an adult man daily is about three pints, 
in addition to that which forms a part of the solid 
food. The quantity used varies enormously, accord- 
ing to the waste. In a hot day in summer we need 
much more than in cold weather, and in damp days 
much less than on dry ones. 
52. Salt .—Sa/t, also, is not only an agreeable con- 
diment, but has important offices to perform in the 
body. It has been shown by experiments on ani- 
mals that, if they are entirely deprived of salt, they 
decline very much in vigor, and every farmer knows 
how necessary it is to the health of his cattle and 
sheep.* 
53. Other Inorganic Matters.—There are other 
* Boussingault, a French chemist (bom in 1802), reported in 1854 
some experiments he had made in regard to the importance of salt to 
cattle. He took six bullocks, of about the same age and vigor, and fed 
them alike, excepting that to three of them he gave 500 grains of salt 
every day and to the others none. At the end of six months the hides 
of those that had had no salt were rough and dull in color, while those 
of the others were shining and smooth. At the end of a year the salt- 
fed bullocks were in perfect health, while the others were dull and 
stupid, and the hair upon their hides was rough and tangled, with bare 
patches here and there. 
Wild animals, especially of the grazing kind, like deer and cattle, 
will travel long distances in search of salt, and seem to be as fond of 
it as children are of sugar. FOOD, 
45 
inorganic matters which are essential to the growth 
and nutrition of the body, but which are naturally 
found in articles of food and are not taken sepa- 
rately. Such are the salts of lime, soda, potash, and 
magnesia, all of which form a part of our common 
fruits and vegetables. The most important of these 
is probably the lime phosphate which forms so great 
a part of the bones. The husk of grain contains a 
certain proportion of this salt, and in growing chil- 
dren, in whom the cartilaginous portions of the 
bones are becoming ossified, wheaten grits or Gra- 
ham bread is a very welcome and advantageous ar- 
ticle of diet. It has been affirmed that the large size 
of the inhabitants of Kentucky is due to the fact that 
they live in a limestone region, and the water they 
use is strongly impregnated with lime. So large a 
proportion of lime taken into the body, at a time 
when the bones are forming and growing and hard- 
ening, is said to make them longer and stronger 
than they would be otherwise. 
54. Non-nitrogenous Foods. — The non-nitroge- 
nous, or, as they are sometimes called, the carbonaceous 
foods, are sugar, starch, and fat. These substances 
are all composed of carbon, hydrogen, and oxygen, 
in varying proportions, the sugar and starch taken 
in our food being mostly of vegetable origin, while 
the fat may be either animal or vegetable. 
55. Starch.—Starch forms a part of all grains and 
most vegetables, sago, tapioca, arrowroot, etc., be- 
ing almost pure starch, which has been extracted 
from the plants in which it is found. Rice contains 
about 85 per cent of starch, wheat about 70 per 
cent, and the potato about 15 per cent. This latter 
amount seems very small, but most of the remainder 46 
ORGANS OF REPAIR. 
of the ioo parts of the potato consist of water, and 
starch really forms the bulk of the solid matter. 
It is a peculiarity of starch that it is very easily 
converted into sugar. This is actually accomplished 
in the human body, during the processes of masti- 
cation and digestion, as will be shown hereafter. 
56. Sugar.—Sugar is taken in our food in various 
forms, for it has not always the same chemical com- 
position. It is always sweet, and is always easy to 
recognize as sugar, but varies in its proportions of 
carbon, hydrogen, and oxygen. Thus we find that 
cane-sugar, milk-sugar, and grape- or honey-sugar 
(often called glucose *), all differ from each other. 
Sugar is taken partly as an addition to the food for 
the sake of improving its flavor, and partly as a nat- 
ural constituent of vegetables and particularly of 
fruits, some of which contain an enormous propor- 
tion of it. Figs, for example, are more than half 
sugar, and hardly any fruit contains less than 10 per 
cent. 
57- Fat .—Fat is found in almost all parts of the 
body, and particularly just underneath the skin, 
where it serves to give rounded outlines to the form, 
and also undoubtedly acts as an elastic cushion to 
protect the parts beneath from injury. During life, 
owing to the warmth of the body, the fat is fluid and 
transparent; f but after death, as the body cools, it 
* Glucose is now produced artificially in enormous quantities by the 
use of sulphuric acid and corn. When anything containing starch is 
boiled with this acid, the starch is converted into glucose, which is the 
kind of sugar found in fruits. Cane-sugar can be changed into glucose 
in the same way, and as a matter of fact it is changed into glucose in 
the act of digestion, so that glucose must be looked upon as that form 
of sugar that it is natural for us to take in our food. 
f If the fingers be held close together in front of a bright light, the FOOD. 
47 
becomes solid. The fat which is found in the body 
is not all taken in with the food, but a certain amount 
of it is formed in the body itself, in a manner which 
is not yet understood. Certain articles of diet tend 
to increase the amount of fat in the body. This is 
notably the case with starch and sugar. In sugar- 
growing countries, as the Southern States, it is a 
matter of common observation that the negroes grow 
fat and sleek during the sugar-season, and lose their 
superabundant flesh when the season is over. Arti- 
cles of food which contain much starch also increase 
the amount of fat. The famous Banting system of 
treating corpulence is based on this fact, and con- 
sists mainly in depriving the patient of starchy vege- 
tables, grains, and sugar.* 
58. Nitrogenous Foods.—The nitrogenous portion 
of our food is also both animal and vegetable, but 
chiefly animal. The principal substances of this class 
are fibrin, albu'men, and ca'se'in. They all contain a 
considerable amount of nitrogen, in addition to 
carbon, hydrogen, and oxygen, and are generally 
called by physiologists pro'teid substances, or the 
proteids. 
Casein is found in large proportion in milk, from 
which it is extracted to form cheese, and the two 
rosy tinge of their borders shows that they are to a certain extent trans- 
lucent. The fingers of a corpse, under similar conditions, are opaque. 
* Mr. Banting, the court undertaker, was put under treatment for 
corpulence by Mr. William Harvey, a London surgeon. He w7as al- 
lowed to eat any meat except pork, any kind of fish except salmon or 
eels, any vegetables except potatoes or rice, any kind of poultry or 
game, dry toast, fresh fruit, tea without milk or sugar, and to drink 
claret, sherry, or madeira wine, or gin, whisky, or brandy without sugar. 
When he began this diet in August, 1862, he weighed two hundred 
and two pounds, and a year after, he had lost forty-six pounds, and 
reduced his girth twelve and a quarter inches. 48 
ORGANS OF REPAIR. 
others are found mostly in the animal fluids, and in 
muscular fiber. 
There are also substances very much like the 
animal albumen and casein which are found in vege- 
tables, but they present slight chemical differences, 
although they probably answer nearly the same 
purpose in nutrition. Peas and beans contain a con- 
siderable quantity of the vegetable casein. 
59. Necessity of Variety of Food.—It is neces- 
sary, for the preservation of health, that our food 
should contain a sufficient amount of these different 
kinds of matter. We must have water; we must 
have salt and the lime compounds mentioned above ; 
we must have starchy substances (much the same to 
the body as sugar) and fats,* and we must have a 
certain amount of nitrogenous food. If one of these 
be lacking, the body soon feels it, and, although the 
person may not know precisely why he feels bad, 
he will often recover from his temporary disorder 
by a mere change of diet. The lack of any particu- 
lar ingredient in our food is often indicated to us by 
a longing for it. We feel a strong desire to eat par- 
ticular things and no others, and such a desire may 
generally be taken as a safe indication that the body 
needs them. 
60. Paramount Necessity of Water.—Of all arti- 
cles used for food or drink, water, in some form 
or other, is the most indispensable. Men can live 
much longer on water without food than on food 
without water. The celebrated French physiolo- 
gist, Magendie, found that dogs lived eight or ten 
* This is said of a healthy person. Excessive production of fat, as 
in Mr. Banting’s case, is to be regarded as a diseased condition, and so 
requires special diet. FOOD. 
49 
days longer, when supplied with water alone, than 
when they were deprived of both food and water. 
The pangs of thirst have been felt in a slight de- 
gree by almost every one, and it is the experience 
of those who have suffered from deprivation of 
food and water, in deserts and shipwrecks, that the 
tortures of thirst are much harder to bear than 
those of hunger. 
61. Daily Amount of Food.—It has been found 
by Dr. Dalton, by experiments upon himself, that 
an adult requires food in about the following pro- 
portions : 
Meat 16 ounces. 
Bread 19 “ 
Butter, or fat 3|- “ 
Water 52 “ 
or about two pounds and a half of solid food and 
about three pints of liquid food daily. This is 
about the least amount which will keep him in 
good health. 
62. Cooking.—Man does not take his food in 
the natural state, like other animals, but prepares 
it by cooking. This process is of advantage in two 
ways: it softens the hard parts of the food, such 
as beans, potatoes, and the various grains, and the 
fibrous tissue of meat; and it also develops a pleas- 
ant flavor by the action of heat, which excites the 
flow of the fluids of the mouth and stomach, and 
thus aids digestion. CHAPTER II. 
MASTICATION.—SWALLOWING. 
63. The Digestive Apparatus.—The food we 
eat is mostly insoluble, and in an unfit condition 
to be used for the nourishment of the body. Even 
so nutritious a substance as albumen can not be 
used without undergoing some change, and if pure 
fluid albumen be injected directly into the blood, it 
will be thrown out of the body by the kidneys un- 
altered. To prepare the various foods for use in 
the body, we are provided with a complicated series 
of organs, called the digestive apparatus, in which 
the food is ground fine and mingled with various 
juices until it is reduced to a fluid mass, which can 
be taken up by the blood and carried to all parts 
of the body in a condition fit for their nutrition. 
64. Processes to which Food is subjected in 
the Body.—The process of preparing food for our 
nourishment may be conveniently divided into 
five stages. The first of these is mastication, which 
takes place in the mouth, and is a voluntary act. 
The second is swallowing, or the act of passing food 
on from the mouth to the stomach, the beginning 
of this act being voluntary, and the greater part of 
it involuntary. The third is stomach digestion, which 
is involuntary ; the fourth, intestinal digestion, which MASTIC A TION.—S WALLO WING. 
51 
Fig. 19.—Front view of the organs in their natural relations. The heart is 
partly covered by the lungs, but its true outline is indicated by a dotted 
line. Only ten ribs are shown on each side, the eleventh and twelfth 
(the floating ribs) being too short to be included in the section. 52 
ORGANS OF REPAIR. 
is involuntary ; and the fifth is the process of ab- 
sorption, which is also a process of selection, by 
which certain portions of the prepared mass are 
taken up into the circulation for food, and the rest 
left in the intestines as waste material; this whole 
process is also beyond the control of our will; all 
waste matters are then expelled from the body. 
65. Only One Voluntary Process.—All of these 
processes must be properly conducted, in order to 
maintain the body in a healthy condition. They 
are all important, and, if one be neglected or carried 
on in a disordered and unnatural manner, the others 
will all be affected, by reason of their close connec- 
tion with and dependence on each other. Only one 
of them is directly under the control of the will, and 
every one can do more toward preventing dyspep- 
sia and other disorders of the digestive organs, by 
paying some attention to the proper and complete 
mastication of his food than in almost any other 
way. If we examine the mouth, with reference to 
its uses in mastication, we find it prepared to per- 
form three great and important functions. 
66. Use of the Taste and Smell.—In the first 
place, it is provided with an organ of taste, to assist 
us in selecting our food. In this it is aided by the 
proximity of the nose, so that we have the addi- 
tional advantage of the sense of smell. And the 
nose is not only so situated as to aid us in judging 
of food before it enters the mouth, but it is con- 
nected with the throat behind, so that odors are 
detected from substances already in the mouth. 
67. The Teeth.—In the second place, the mouth 
is provided with organs for grinding and crushing 
the hard parts of the food, and reducing them to a MASTIC A TION.—S WALLO WING. 
53 
soft mass, fit to be acted upon by the fluids in the 
stomach and intestines. The organs directly of 
use in this operation are the teeth (Fig. 20), but 
essential aid is afforded by the mus- 
cles of the cheeks and the tongue. 
The rows of teeth are narrow, and, 
except for the action of these mus- 
cles, the food could not be kept be- 
tween them. Indeed, it has been 
found that in cases of paralysis, 
when the muscles of the cheek are 
unable to contract, while the tongue 
still retains its power, the food gets 
pushed out between the cheek and 
the teeth, and accumulates there. 
The lower jaw is moved by some 
of the most powerfully acting mus- 
cles in the body. The chief one of all is the mas'- 
seter, which is attached above to the ridge of bone 
running backward from the lower border of the 
eye toward the ear, and below to the horizontal 
portion of the jaw. The muscle is nearly square in 
shape, and, as is easily seen, acts at a great mechan- 
ical advantage. As a matter of interest connected 
with this muscle, it may be stated that it is the mus- 
cle generally referred to for proof that muscular 
contraction is accompanied by a sound. If the 
lower jaw be firmly closed, and the teeth powerfully 
pressed together so that the muscles of mastication 
are strongly contracted, a low, rumbling sound will 
be heard, which can not be explained in any other 
way than as caused by the muscular contraction. 
68. The Saliva.—In the third place, the food, 
while undergoing mastication, is mixed with cer- 
Fig. 20.—Section of a 
tooth. The black 
portion is the cav- 
ity occupied by the 
nerve and blood- 
vessels. 54 
ORGANS OF REPAIR. 
tain fluids, called collectively the saliva. They are 
the product of three sets of glands, each of which 
is double—i. e., there are three glands on each side 
of the mouth (Fig. 21), and the secretion of each 
Fig. 21.—The salivary glands of the right side. 
pair is peculiar to itself. The largest of these are 
the parot'id glands, which are situated just in front 
of the lower border of the ears, and are the glands 
which become swollen and cause the distortion of 
the face in the disease known as the mumps. The 
fluid secreted by these glands is very thin and 
watery, and constitutes the greater part of the sa- MASTIC A TION.—S IVALLO WING. 
55 
liva. The other glands are situated just inside the 
lower border of the jaw and beneath the tongue. 
Their secretion is much thicker and more glutinous 
than that of the parotid glands. Besides these 
fluids, there is a small amount secreted by the 
mucous membrane lining the mouth, and all these 
mingled fluids constitute the saliva. 
The saliva is secreted to some extent at all 
times, and keeps the lining membrane of the mouth 
moist and soft, but it is a familiar fact that its 
amount is greatly increased at certain times. Thus, 
we say, at the sight, or even sometimes at the sug- 
gestion, of an appetizing meal, the “ mouth waters.” * 
The fact of its excessive secretion at such times 
shows that it has a part to perform in the process 
of mastication and digestion. 
69. Properties and Use of the Saliva.—Experi- 
ments have shown that saliva possesses the property 
of converting starch into sugar; but, as this is also 
done by the digestive fluids, it is not considered to 
be a very important function, and the chief use of 
the saliva undoubtedly is, to make the processes of 
mastication and swallowing of food easier. If food 
were taken dry, and there were no means at hand 
of moistening it, mastication would be very difficult 
and tiresome, and swallowing almost impossible. 
Bernard f found, by experiments upon a horse, that 
* In physiological lectures before medical students, it is not uncom- 
mon to illustrate this fact in a curious way. A slender tube is intro- 
duced into the opening by which the parotid saliva is discharged into 
the mouth, and, according to the condition of the person operated on, 
there will either be no flow of saliva or it will come out drop by drop. 
But now let food be brought in, and the moment it is seen the saliva 
begins to run from the tube in a plentiful stream. 
f Claude Bernard, a famous French physiologist (1813-1S7S). He 56 
ORGANS OF REPAIR. 
when an operation had been performed, which pre- 
vented the parotid saliva from entering the mouth, 
the animal could masticate and swallow (the latter 
process being accomplished with great difficulty) 
only three quarters as much oats in twenty-five 
minutes as he had previously eaten in nine. It is 
probable that the parotid saliva, which is almost 
like water, assists mainly in the mastication of the 
food; while the other secretions, which are thicker 
and more slippery, coat the outside of the mass, and 
render it easier to swallow. 
The total amount of saliva secreted by a healthy 
adult in twenty-four hours has been calculated, after 
numerous experiments, to be nearly three pounds. 
Note.—It is important for the health of the individual that the 
teeth should be kept in good condition, in order that mastication may 
be thorough and complete. Particles of food which stick between the 
teeth, if they are allowed to remain, putrefy and impart an offensive 
odor to the breath. The acids which are developed during the putre- 
faction of such matters are also injurious to the teeth and tend to hasten 
their decay. There are also certain substances deposited from the 
saliva around the necks of the teeth, called “tartar.” If this is not 
removed, the gums are bruised against it, and finally recede from the 
teeth, leaving a part of the fang bare, and thus exposing to all sorts o( 
injurious influences a part of the tooth which was never intended to 
be so exposed. 
The teeth should therefore be frequently cleaned, at least twice a 
day, with water and a soft brush (a stiff brush injures the gums), tooth- 
picks being used when necessary. Avoid fancy tooth-powders and 
washes, for they often contain injurious acids or gritty substances. To 
polish the teeth, use powdered orris-root and chalk, which can be 
bought of any druggist. Never crack nuts with the teeth, and, on the 
slightest appearance of decay, consult a good dentist. 
was Professor of Physiology in the College of Franee from 1855 until 
his death. Especially distinguished for his discovery of the formation 
of sugar in the liver, and for his researches on the functions of the sym- 
pathetic nervous system. (See later.) CHAPTER III. 
STOMACH-DIGESTION. 
70. The Alimentary Canal.—The food, which is 
now ready to be operated upon by the digestive 
fluids, passes beyond the control of the person who 
swallows, and begins its travels in the long tube, 
called the aliment'ary canal (Fig. 22). This canal 
begins at the mouth and ends with the large intes- 
tine, and is nearly thirty feet in length. It does 
not properly assume the form of a tube until the 
beginning of the cesoph'agus, or gullet, and at one 
point, namely, at the lower extremity of the oesoph- 
agus, there is a considerable enlargement, which 
has the appearance of a bag or pouch, and is called 
the stomach. To understand the working of the 
alimentary canal, it is necessary to know something 
of its anatomy. 
The two most important tissues in its structure 
are the mucous membrane which lines it through- 
out, and the muscles which surround it, and are im- 
bedded in its walls. 
71. Mucous Membrane.—Mucous membrane (Fig. 
23) is the skin which lines the interior canals of the 
body. While the outside of the body is covered 
by a smooth, white, tough skin, we see that, at the 
openings leading to its interior, such as the mouth, 58 
ORGANS OF REPAIR. ■ 
nose, etc., the character of this covering suddenly 
changes, and it becomes a reddish or pinkish mem- 
Fig. 22.—The alimentary canal. 
brane very soft and delicate in texture, and con- 
tinually moistened by its secretions. This is called 
mucous membrane, and in one form or another it 
lines all those internal parts of the body, which 
communicate with the external air. 
It is made up largely of fibrous tissue, consisting 
of fine threads, interlacing with each other in every 
direction and densely woven. Its surface is cow STOMACH-DIGESTION. 
59 
ered with minute cells, called epithelial cells* At 
various points on the membrane are minute tubes 
or cavities, less than 
of an inch in diam- 
eter,of different shapes 
in different places, and 
in some situations so 
numerous that they lie 
almost in contact with 
each other. These mi- 
nute tubes are closed 
at the bottom, but 
open on the surface of the membrane. Small as 
they are, they are lined from top to bottom with 
epithelial cells, which really carry on the work of 
secretion. All around, among, and underneath 
these tubes are small blood-vessels, which nourish 
the membrane, and from which the little epithelial 
cells separate the materials which form the mucus. 
72. Muscles of the Alimentary Canal.—The mus- 
cles which form a considerable part of the walls of 
the alimentary canal are of the involuntary or non- 
striated kind. The fibers run in various directions, 
some of them surrounding the oesophagus and the 
Fig. 23.—Structure of mucous membrane 
illustrated. At one side is a detached 
portion of a tube, or follicle, enlarged so 
as to show the epithelium more clearly. 
* All free surfaces of the body, whether inside or outside, are cov- 
ered with cells. In the interior of the body, the alimentary canal, the 
lungs etc., these cells are soft, and, so to speak, plump, and are called 
epithelial cells, or a mass of them taken together is called epithelium. 
On the external surface of the body they are dry, flat, hard, and horny, 
and are called epidermal cells, or, in a mass, the epidermis. In both 
situations they are being constantly shed and renewed. The fresh 
ones are continually forming underneath, and, as they grow, take the 
place of the old ones on the surface, which are being constantly rubbed 
off in one way or another. All the secretions of mucous membranes 
contain these epithelial cells, and the slightest scraping of the skin dis- 
lodges epidermal cells. 60 
ORGANS OF REPAIR. 
intestines in a circle, so that when they contract 
they make the canal smaller; while others run 
lengthwise, and their contraction shortens the ca- 
nal. When these two kinds of fibers, the circular 
and the longitudinal, contract together, they propel 
forward anything that comes within their grasp. 
73- Serous Membrane.—Besides these parts of 
their structure, the stomach and intestines are cov- 
ered on the outside by what is called a serous mem- 
brane’, which is found lining all cavities inside the 
body that do not communicate with the air, ex- 
cepting the joints. This kind of membrane is trans- 
parent, exceedingly fine and soft, and smooth like 
satin, and is constantly moistened with a slight 
amount of fluid. The use of serous membrane is 
to allow organs to move freely upon each other 
without friction. If it were not for some provision 
of this sort, the movements of the stomach and in- 
testines during digestion would be painful, or at 
least disagreeable, while, as things now are, we are 
entirely unconscious of any movement at all. 
74. Swallowing.—After mastication is completed 
the tongue passes the mass of food backward into 
the pliar'ynx (or throat), whence it goes on into the 
oesophagus. The cesopJiagus (Fig. 24) is about nine 
inches long, and extends from the throat to the 
stomach, not just behind the breastbone, as many 
suppose, but just in front of the spine. The mus- 
cles of the upper portion are of the striated variety, 
but, nevertheless, their contraction is not voluntary. 
When anything has once passed to the back of the 
throat, it will be swallowed and sent into the stom- 
ach, in spite of our will. 
75. The Stomach.—The stomach varies in size 5 TOMA CH-DIGES TION. 
61 
in different persons, but on the average will con- 
tain about three pints of fluid in the adult. Its 
Fig. 24.—Vertical section of the head and neck. At the base of the tongue 
is seen the epiglottis, and below this the larynx. Between the larynx 
and the bodies of the vertebras lies the oesophagus. 
shape has often been compared to that of the air- 
bag of a bag-pipe, which it much resembles (Fig. 
25). It has two openings, one at the lower extrem- 
ity of the oesophagus, where food enters, and the 
other at the point where food passes out and the 
small intestine begins. These openings are both in 62 
ORGANS OF REPAIR. 
the upper border of the organ, and only a short dis- 
tance apart, the pylo'rus, or exit, being at the right 
Fig. 25.—Outside of the stomach, front view, showing the muscular coat. 
extremity, and the car'diac opening near the mid- 
dle.* The stomach extends toward the left for 
about three inches beyond the cardiac orifice, and 
is larger in this part than in any other. This por- 
tion is called the great pouch of the organ (Fig. 26). 
Each orifice is guarded by a powerful muscle, 
surrounding it in a circular form, which can con- 
tract so tightly as to prevent the passage even of a 
fluid. As a rule, these muscles prevent the passage 
of any substance backward through them, in oppo- 
sition to the natural course of the food. 
* Pylorus, a Greek word meaning the gate-keeper / cardiac, from a 
Greek word meaning the heart, because it is very near that organ. 5 TOMA CH-DIGES T/ON. 
63 
76. Stomach-Digestion. — It was formerly sup- 
posed that the whole process of digestion was 
Fig. 26.—Inside of the stomach, front view, showing the folds (or rugae) of 
the mucous membrane. 
performed in the stomach, but this is now known 
not to be the case. The nitrogenous portions of 
the food are the only ones that are digested in the 
stomach. The oily and fatty, as well as the starchy, 
portions are digested in the small intestines. Fluids 
are very rapidly absorbed by the stomach. 
77. Dr. Beaumont and St. Martin.—There are so 
many difficulties connected with the investigation of 64 
ORGANS OF REPAIR. 
the subject of digestion, that very little was really 
known about it until the year 1833, when a small 
book was published by Dr. Beaumont, of the United 
States Army, giving physiologists their first precise 
knowledge of what takes place in the human stom- 
ach. His observations were so well taken, that 
very little has been added since to what he dis- 
covered upon the particular subject of stomach 
digestion. 
In the year 1822, Alexis St. Martin, a stout young 
French Canadian, in the employ of a fur-trading 
company, and about eighteen }7ears of age, received 
a severe wound in the left side from the accidental 
discharge of a shot-gun at a distance of about three 
feet. He was attended by Dr. Beaumont, and, 
although his recovery was slow, his health was 
finally completely re-established, and he was still 
living in Vermont, the father of a numerous famity, 
at a very recent date. In the situation of the 
wound, however, was left an opening into the 
stomach, about four fifths of an inch in diameter, 
closed by a flap or valve of mucous membrane on 
the inside. This valve could be pushed inward, but 
not outward ; and thus, although the operation of 
digestion was not at all interfered with, the interior 
of the stomach could be thoroughly examined, and 
experiments performed with the greatest facility 
and accuracy. Dr. Beaumont kept the young man 
in his employ for several years, and made hundreds 
of observations upon him. These were published 
in his little book, and made both him and St. Martin 
immediately famous. 
As Dr. Beaumont was the first, and for many 
years the only, person who ever saw the interior of STOMACH-DIGESTION. 
65 
the stomach in a living man, much of the following 
description will be taken from his volume. 
78. Interior of the Stomach.—“ The interior coat 
of the stomach,” he says, “in its natural and healthy 
state, is of a light or pale-pink color, varying in its 
hues according to its full or empty state. It is of 
a soft or velvet-like appearance, and is constantly 
covered with a very thin, transparent, viscid mucus, 
lining the whole interior of the organ.” 
79. The Gastric Juice.—The changes which the 
food undergoes in the stomach are due to the action 
of the gastric juice, the appearance of which, with 
the manner of its secretion, is thus described: 
“ By applying aliments or other irritants to the 
internal coat of the stomach, and observing the 
effect through a magnifying-glass, innumerable mi- 
nute lucid points can be seen arising from the 
mucous membrane, and protruding through the 
mucous coat; from which distils a pure, limpid, 
colorless, slightly viscid fluid. This fluid is inva- 
riably distinctly acid.” 
“ The fluid so discharged is absorbed by the 
aliment in contact, or collects in small drops and 
trickles down the sides of the stomach to the more 
depending parts, and there mingles with the food 
or whatever else may be contained in the gastric 
cavity.” 
“ The gastric juice never appears to be accumu- 
lated in the cavity of the stomach while fasting. 
When aliment is received, the juice is given out in 
exact proportion to its requirements for solution, 
except when more food has been taken than is necessary 
for the wants of the system." 
80. Composition and Amount of Gastric Juice.— 66 
ORGANS OF REPAIR. 
The gastric juice contains two important constitu- 
ents, viz., hydrochloric acid and pepsin. If it be 
deprived of these, it will no longer exhibit its pe- 
culiar properties; while, if it retains them, as Dr. 
Beaumont first showed, it will digest food in a glass 
tube, outside the body, provided the tube and its 
contents be kept at a temperature of ioo° Fahr., 
which is about the ordinary temperature inside the 
stomach. 
The average amount of gastric juice secreted 
daily by an adult human being has been estimated 
at a little less than fourteen pounds, or about a gallon 
and a half. 
81. Movements of the Stomach. — But, besides 
the action of the gastric juice in stomach-digestion, 
a very important office is performed by the muscles 
which form a large part of the walls of the organ. 
During digestion, these muscles are continually 
contracting in a slow, regular order, producing 
movements of the contents of the stomach in a 
very peculiar manner, which, in health, never varies. 
Dr. Beaumont says that the ordinary course and 
direction of the revolutions of the food are first, 
after passing out of the oesophagus into the stom- 
ach, from right to left, thence down along the great 
curvature, from left to right, to the pylorus, whence 
it returns again along the upper border of the or- 
gan to the left extremity of it. Each of these jour- 
neys of the food around the organ occupies from 
one to three minutes, and they serve to mingle the 
gastric juice more thoroughly with the food. As 
soon as the process of digestion is gone so far as to 
bring portions of the food into a condition for ab- 
sorption, it is found that every time the contents of 5 TOMA CH-DIGES TION. 
67 
the stomach pass the pylorus the mass becomes di- 
minished in amount, showing that a portion has 
been squeezed or pressed through the opening into 
the intestine. 
“ These peculiar motions and contractions con- 
tinue until the stomach is perfectly empty, and not 
a particle of food remains. Then all becomes quiet 
again.” 
Thus that part of the digestion of food which is 
carried on in the stomach is accomplished by the 
action of the gastric juice, and the changes pro- 
duced by it are assisted, and the prepared food is 
passed out of the stomach, by the constant contrac- 
tions and churning motions of the organ just de- 
scribed. 
This, then, is the ordinary healthy process of 
stomach-digestion, when not in any way hindered 
or interfered with. Let us see what changes take 
place in the appearance of the stomach and in its 
functions when it is injuriously affected. 
82. Appearance of the Stomach during Indiges- 
tion. — “ In a feverish condition, from whatever 
cause—obstructed perspiration, undue excitement 
by stimulating liquors, overloading the stomach 
with food—fear, anger, or whatever depresses or 
disturbs the nervous system,” the lining of the stom- 
ach “ becomes somewhat red and dry, at other times 
pale and moist, and loses its smooth and healthy 
appearance ; the secretions become vitiated, greatly 
diminished, or entirely suppressed.” 
“ There are sometimes found, on the internal 
coat of the stomach, eruptions or deep-red pimples. 
These are at first sharp-pointed and red, but fre- 
quently become filled with white purulent matter; 68 
ORGANS OF REPAIR. 
at other times, red patches, from half an inch to an 
inch and a half in circumference, are found on the 
internal coat. These appear to be the result of con- 
gestion in the minute blood-vessels of the stomach.” 
“ These diseased appearances, when very slight, 
do not always affect essentially the gastric appa- 
ratus. When considerable, and particularly when 
there are corresponding symptoms of disease, as 
dryness of the mouth, thirst, furred tongue, etc., 
no gastric juice can be extracted. Drinks received 
are immediately absorbed or otherwise disposed 
of; none remaining in the stomach ten minutes after 
being swallowed. Food, taken in this condition of the 
stomach, remains undigested for twenty-four or forty- 
eight hours or more." 
“ Whenever this morbid condition of the stom- 
ach occurs, with the usual accompanying symptoms 
of disease, there is generally a corresponding ap- 
pearance of the tongue. When a healthy state of 
the stomach is restored, the tongue invariably be- 
comes clean.” 
These are the observations of one who saw what 
he describes, and took careful notes of what he 
saw. 
83. Time required for Stomach-Digestion.—The 
time required for digestion in the stomach varies 
very much according to the character of the food. 
Dr. Beaumont found that the time of stomach-di- 
gestion in St. Martin varied from one hour to about 
five and a half. Among meats, the soonest digested 
was boiled pig’s feet, which took an hour, and the 
longest time was taken for roast pork, viz., five 
hours and a quarter; among vegetables, rice is di- 
gested in an hour, while boiled cabbage requires STOMACH-DIGESTION. 
69 
four. The average time required for an ordinary- 
meal is probably about three hours. 
84. Advantage of Thorough Mastication.—Dr. 
Beaumont found that, when a piece of meat or other 
food is attacked by the gastric juice, it is slowly 
dissolved from the outside. The juice is not soaked 
up and does not penetrate the interior of the mass, 
but gradually softens the exterior of it; and, as 
the outside portion becomes friable and dissolves, 
the piece grows smaller and smaller, the gastric 
juice in this way advancing little by little, until the 
whole mass is liquefied. From this it is evident 
that it will take longer to digest a large piece of 
meat than to digest the same amount after it has 
been divided into small pieces ; for this reason it is 
important to masticate the food thoroughly before 
sending it into the stomach. 
85. Eating too little.—It is evident that it will 
not do to take too little food. Enough must be 
eaten to supply the needs of the system, and it 
must be of such a quality that it can be readily di- 
gested and appropriated. 
86. Eating too much.—But, on the other hand, 
we must not take too much food. There seems to be 
some subtile relation between the amount of food 
required by the system and the amount of gastric 
juice furnished by the stomach. What is likely to 
be the result, then, if more food is taken into the 
stomach than can be acted on by the gastric juice? 
Let us consider. The temperature of the interior 
of the stomach is about ioo° Fahr. This is just 
about the temperature at which fermentation and 
putrefaction (which is a sort of fermentation) are 
most active. Heat and moisture favor these pro- 70 
ORGANS OF REPAIR. 
cesses. Both of these conditions exist in the stom- 
ach, but, under ordinary circumstances, the gastric 
juice prevents any other changes than those due 
to its own action. But, if more food is introduced 
than the gastric juice can dissolve, fermentation 
occurs, and offensive gases and irritating acids are 
produced. Then the symptoms of indigestion come 
on, there is constant belching of wind from the 
mouth, an uneasy sensation in the stomach, and, as 
soon as the undigested and fermenting mass passes 
out into the intestine, rumblings and colic set in, 
followed probably by a diarrhoea, which continues 
until the offending matters have been ejected from 
the body. 
87. Eating between Meals.—Similar symptoms 
may be produced by eating between meals. When a 
sufficient meal has already been eaten, we should 
wait until it has been digested and the stomach has 
had a short period of rest before we give it any 
more work to do. This organ can not work inces- 
santly any more than other parts of the body, and 
when it is ready for more food the sensation of 
hunger apprises us of the fact. If we load it with 
fresh food before the previous supply has been dis- 
posed of, there may not be enough gastric juice 
secreted to digest it. Then it ferments, or putre- 
fies, and causes a fit of indigestion, as .just described. 
88. Hunger.—It is sometimes said that a person 
should rise from the table, after every meal, still 
hungry. This is not correct, and the reason is 
plain. Hunger is the natural indication that the 
body is beginning to be worn out, and needs fresh 
material to repair its losses. And although the 
appropriation of the food is finally made by the STOMACH-DIGESTION. 
71 
cells that compose the body, and so must be after 
it has been already digested and carried to them, 
nevertheless the sympathy of the different parts of 
the body with each other is such that hunger is 
satisfied by the mere act of supplying food to the 
stomach. Not only that, but the digestibility of 
the food has a great deal to do with it. Certain 
kinds of food, which we call rich, generally contain- 
ing a great deal of fat and sugar, satisfy the hunger 
and produce a sense of satiety, when we have not 
really eaten enough to supply the bodily needs. 
This is because such food is digested very slowly, 
being so permeated with fat that the gastric juice, 
which does not digest fat, penetrates to the albumi- 
nous portions of the food with great difficulty. In 
such cases also fermentation frequently occurs, and 
persons who eat much so-called rich food may satis- 
fy their hunger with it day after day, and still suffer 
from indigestion, and not get enough nourishment 
to repair the waste of the body. For these reasons, 
plain food is the best, especially for the young. 
89. How much to eat.—The true way, there- 
fore, is not to rise hungry from the table, but to 
stop eating when the hunger has been satisfied, and 
before any feeling of repletion comes on. It should 
be borne in mind that the process of digestion 
ought to go on without our consciousness. After 
a proper meal, the only sensation caused by the 
food we have taken should be that of complete 
satisfaction and contentment. If the stomach feels 
stuffed and full, we have eaten too much. It may 
be properly disposed of if the eater is in vigorous 
health, and able to rest for a time until the uneasy 
feeling of repletion wears away. But the whole 72 
ORGANS OF REPAIR. 
process ought to go on without causing us a mo- 
ment’s thought. If we are healthy, and if we treat 
our digestive organs properly, we ought never to 
feel that we have a stomach, or liver, or bowels. 
They will never trouble us, if we do not trouble 
them. 
Our meals, therefore, should be sufficiently far 
apart to allow an hour or two at least to intervene 
between the digestion of one meal and the begin- 
ning of another. As digestion in the human being 
ordinarily occupies from three to four hours, our 
meals should be at least five hours apart, and this 
is about the time usually allowed. 
90. What to eat.—The matter of what to eat, 
amid the great variety of foods, may safely be left, 
in a healthy person, to the appetite. It is a familiar 
proverb that “ one man’s meat is another man’s 
poison.” Each individual must learn for himself 
what food is the best for him. If any article is 
found to disagree, it should thereafter be let alone; 
no attempt should be made to overcome a natural 
repugnance, and acquire an appetite for what is 
distasteful. This is to fly in the face of Nature; it 
is much the same as saying that one is competent 
to direct the secret processes of nutrition and to 
regulate the functions of organs, about which he 
knows almost nothing, and which he can not con- 
trol. Such action is intermeddling, not judicious 
care. 
91. Condiments. — Something should here be 
said, however, about the use of certain substances 
which are not foods, and yet are in common use 
throughout the world, to make food more accepta- 
ble to the palate. Such substances are pepper and STOMACH-DIGESTION. 
73 
mustard. These condiments have two qualities 
that have caused them to be used in the prepara- 
tion of food, viz., a peculiar flavor, which makes 
articles of food to which they have been added 
more savory, and a quality called pungency—i. e., 
they irritate any part of the body with which they 
are brought in contact. When either is placed 
upon the tongue, smarting is produced, sometimes 
to a painful degree, and tears start in the eyes. 
The effect can therefore be imagined when these 
substances are rubbed over the delicate mucous 
lining of the stomach during the movements of 
digestion. They can not but be extremely irritat- 
ing, and therefore injurious. As a matter of fact, 
the excessive use of such things, whether alone 
or in highly-seasoned sauces (Worcestershire, etc.), 
results in extreme debility of the digestive appara- 
tus and confirmed dyspepsia. The golden rule in 
the treatment of the stomach is, to put nothing into 
it that can be felt after entrance. As before stated, 
the operations of the stomach ought to go on with- 
out our consciousness of them. If enough spice is 
taken to produce a feeling of warmth in that organ, 
it is too much, and the mucous membrane has been 
irritated. We are all, or nearly all, born into the 
world with sound digestive organs, which need no 
spurring to make them do their duty. If they get 
out of order, it is our own fault, and rest will do 
more than anything else to set them right. If you 
whip a good horse, when he is doing his best, you 
will spoil him. 
92. The Natural Drink.—The natural drink of 
all animals is water, for milk is to be looked upon 
as a food. Many people, however, are not satisfied ORGANS OF REPAIR. 
74 
with water alone, but prefer it flavored with some- 
thing else, and a great variety of drinks have been 
invented, of which we shall only consider tea, cof- 
fee, and those which contain alcohol, as malt and 
spirituous liquors and wines. 
93. Effects of Alcohol; Intoxication.—Alcohol 
is a poison, and the proof of this assertion is clear 
when the ordinary effects of liquors containing it 
are considered. When a person takes so much of 
an alcoholic drink that he feels the effects of it, he 
is somewhat exhilarated, the pulse is quicker and 
stronger, the face is flushed, his ideas seem to flow 
more freely, he is more cheerful and happy, and he 
seems brighter than before. And yet, even in this 
very first stage of intoxication, a close observer can 
see that a poisonous effect has been produced upon 
his nervous system. His judgment is weakened, 
his control over his thoughts is slightly lessened, 
and things, which when strictly sober he conceals, 
often come to the light in his conversation. In 
brief, he is beginning to lose the mastery of him- 
self. If more alcohol is taken, the brain becomes 
more and more oppressed, he loses control of his 
muscular movements, he mumbles in his speech, 
talks nonsense, and finally becomes unconscious. 
The poison, however, if enough has not been taken 
to kill, is gradually ejected from the body, through 
the lungs, skin, and kidneys, and the paralyzed 
organs begin to recover. When consciousness re- 
turns, the person is dreadfully sick with a throbbing 
headache and nauseated stomach, which only recover 
their normal condition after a more or less pro- 
longed period of rest. Surely such effects are not 
those of a food, but of a rank poison. STOMACH-DIGESTION. 
7 5 
94- Narcotic Poisons. — But the more remote 
effects of alcohol are even more striking and of 
greater importance. It is not only a poison but a 
narcotic poison. It belongs to the same class with 
opium, chloroform, ether, hydrate of chloral, etc.; 
the great peculiarity of which is, that they never 
leave the body, through which they have once 
passed, in quite the same condition in which they 
found it. The person who has once taken them is 
apt to feel a desire to take them again. And this 
desire is not like the ordinary appetite for food : it 
is not that their taste or smell is agreeable, for as a 
rule the reverse is the case. It is the after-effect 
that is sought. The oftener this desire is gratified, 
the stronger it becomes, until finally the man is no 
longer master of himself, neglects his daily affairs, 
and takes no interest in anybody or anything but 
plans for obtaining a fresh supply of the poison. 
95. First Symptoms of Narcotism.—This evil 
effect of the narcotic poisons does not follow unless 
enough has been taken to produce the first symp- 
toms of narcotism, which is really the only agree- 
able stage, and is characterized by a curious sort of 
tingling all over the body, somewhat as if the run- 
ning of the blood could be felt in the blood-vessels. 
Indeed, it is probably caused by the contact of the 
alcohol with the millions of cells that compose the 
body, and is the symptom of commencing paralysis.* 
When this sensation is felt, too much alcohol has al- 
ready been taken, and poisoning has begun. 
96. Effect of Alcohol on Growing Persons.—Be- 
* The flushing of the face and the more rapid action of the heart 
are due to the paralyzing effect of the alcohol on the vaso-motor 
nerves, which will be described hereafter. 76 
ORGANS OF REPAIR. 
sides this danger connected with the use of alco- 
holic drinks, which is common to them with other 
narcotic poisons, alcohol retards the growrth of 
young cells and prevents their proper development. 
Now, the bodies of all animals are made up largely 
of cells, as heretofore shown, and, the cells being the 
living part of the animal, it is especially important 
that they should not be injured or badly nourished 
wrhile they are growing. So that alcohol, in all 
forms, is particularly injurious to young persons, as 
it retards their growth, and stunts both body and 
mind. 
97. Effect of Habitual Excess in the Use of Al- 
cohol.—When alcohol is used habitually in quanti- 
ties sufficient to produce symptoms of poisoning, it 
causes serious changes in many parts of the body, 
especially in the stomach, liver, kidneys, and blood- 
vessels. The habitual drinker is therefore never in 
good health, and never lives to be old.* 
98. Alcohol diminishes the Power of Endurance. 
—It has been amply show;n by Arctic explorations 
and by military campaigns in India and Africa, 
that those who use no alcohol endure privation, 
fatiguing labor, and extremes of temperature much 
better than those who take daily rations of grog. 
The common opinion that alcoholic liquors ward off 
the cold and temper the heat arises from the fact 
that the bodily sensations are dulled by the narcotic; 
* It is not to be inferred, from what has been said, that every person 
who uses alcoholic stimulants will become a drunkard, but it can not be 
denied that every such person runs a risk of becoming one. Not every 
one who goes into battle is killed or even wounded, but every one in- 
curs danger. Alcoholic drinks are not necessary to healthy persons, 
and the habitual use of them is like playing with fire near a keg of 
gunpowder. No harm may result, but it is a foolish thing to do. STOMACH-DIGES TION. 
77 
the drinker, in other words, is partially anaesthe- 
tized, so that, although he feels cold and heat in a 
less degree, he is really less able to resist them. 
It is found, also, that even moderate drinkers 
are more likely to be attacked by epidemic dis- 
eases, that they do not bear surgical operations so 
well, that they suffer more from exposure of any 
kind, and that they are apt to succumb to diseases 
from which the abstinent generally recover. 
99. Tea and Coffee.—Tea and coffee are found 
to stimulate the nervous system, producing slight 
exhilaration and relieving exhaustion without the 
subsequent depression that follows the use of alco- 
hol. In excess, however, they produce nervous 
disorders, and, although the moderate use of them 
is not harmful to adults, their influence upon the 
nerves, the most impressionable part of a growing 
person, renders them unsuitable articles of diet for 
the young.* 
100. Confectionery.—Confectionery is not injuri- 
ous, when pure, unless taken in excess. Unfortu- 
nately, it is frequently adulterated, and, instead of 
containing simply sugar, flour, gum-arabic, and 
such harmless substances, is mixed with terra alba 
(gypsum), because it is heavy and cheap. Poison- 
* Of tobacco, it may be said that, although it is a poisonous weed, 
and, when first used, produces alarming symptoms of nervous prostra- 
tion, it is soon tolerated by the system, and becomes a source of great 
comfort and satisfaction to those who use it habitually. The excessive 
secretion of saliva, however, in those who chew it, produces extreme 
thirst, and may thus lead to the habitual use of alcoholic stimulants; 
while tobacco-smoke, constantly irritating the mucous membrane of the 
throat and nose, produces chronic catarrh of those parts. It is said 
that no habitual smoker has a healthy throat. It has been abundantly 
shown that the habitual use of tobacco stunts the growth, and it should 
therefore be shunned by the young. ORGANS OF REPAIR. 
ous coloring-matters are also used. All candy that 
has a gritty feeling in the mouth should be rejected, 
and bright-yellow, orange, and green candies are 
to be looked on with suspicion, for they are almost 
always colored with chromate of lead. 
ioi. Danger of Parasites in Food.—A word of 
caution is necessary about the eating of pork. This 
meat occasionally contains millions of minute para- 
sitic worms, called the trichi'na spira'lis, and, if such 
meat is eaten without killing these worms, they are 
set free in the alimentary canal, bore their way into 
the blood-vessels, and are carried by the current of 
blood all over the body. When they come to ves- 
sels so small that they can not pass, they are stuck, 
dam up the blood-current, interfere with the circu- 
lation, and produce serious and often fatal disease. 
These parasites are killed by a temperature of i6o° 
Fahr., and pork, therefore (including ham, of course), 
should never be eaten unless it is thoroughly 
cooked.* 
Briefly, then, to keep the stomach healthy, masti- 
cate the food thoroughly, cat when you arc hungry, 
avoid overeating and eating between meals, eat plain 
food, do not spur the stomach with condiments or appe- 
tizers, and use alcoholic drinks and tea and coffee, if at 
all, with the greatest moderation and caution. 
* The flesh of the pig occasionally contains anothex- parasite, called 
the cysticer'cus cellulo see, which, if taken alive into the stomach, devel- 
ops into the tape-worm. This parasite, like the trichina, is killed by 
thorough cooking. CHAPTER IV. 
INTESTINAL DIGESTION. 
102. The Chyme.—After the partially digested 
food has passed out of the stomach into the intes- 
tine, it undergoes still further changes, and the 
difficulties of investigation in this part of the body 
are so enormous that very little progress has been 
made toward a clear explanation of what takes 
place there. Enough has been learned, however, 
to give us a general idea of how the process of di- 
gestion is completed. 
We have seen that the fats and the starches 
are not digested in the stomach. The gastric juice 
does not act upon them at all, and they pass into 
the intestine in very much the same condition in 
which they enter the stomach. The fibers and tis- 
sues which hold the fats and starches together, 
being nitrogenous in their nature, are acted upon 
in the stomach and dissolved, so that the fat is set 
free and floats in globules like those upon the sur- 
face of a kettle of soup. The food thus prepared 
to pass into the intestine forms a thick, turbid, gray- 
ish fluid, called the chyme. 
103. The Intestines.—The small intestine, into 
which the food passes from the stomach, is a tube 
about twenty feet in length, and an inch in diame- 80 
ORGANS OF REPAIR. 
ter. It is 'Composed, like the stomach, of three 
layers, the innermost one being mucous membrane, 
the middle one muscular fibers, some of which are 
circular and some longitudinal, and the outer layer 
serous membrane.* 
The small intestine is connected with the large 
one by a valve-like opening situated in the vicinity 
of the right groin. The large intestine passes from 
this point upward to the liver, thence across to the 
left side, and then downward, constituting the last 
five feet of the alimentary canal.f 
104. Muscular Fibers of Intestine.—The muscular 
fibers of the intestine contract with a worm-like 
motion, which always begins near the stomach, and 
extends slowly along the whole length of the intes- 
tine, gradually emptying it of its contents. In this 
* The outer membrane of the in- 
testine of animals, when separated from 
the rest, is used for sausage-casings, 
and, when properly prepared, also 
makes what is called gold-beater’s skin. 
f The beginning of the large intes- 
tine is situated in the right groin, and 
forms a sort of bag or pouch, called 
the caecum. From one side of this 
pouch there projects a slender tube re- 
sembling the intestine in structure, and 
about six inches long. This is called 
the appendix vermiformis, i. e., the 
worm-like appendage (Fig. 27). In 
man it seems to be entirely useless, and 
is in fact a constant source of danger ; 
for occasionally small objects, like 
cherry-pits and grape-seeds, which arc 
swallowed with the food and not di- 
gested, become lodged in it, and grad- 
ually produce an irritation which results in an abscess, and destroys 
life. Such cases are not uncommon in medical practice. 
Fig. 27.—Junction of the small 
and large intestines, and the 
appendix vermiformis. The 
large intestine (here called the 
ccecurn) is cut away so as to 
show the internal openings. INTESTINAL DIGESTION. 
81 
slow passage of the food from the stomach through 
the small intestine to the large one, it is mingled 
with various fluids which complete the process of 
digestion, and the nutritious portions of the mass 
are absorbed and carried away by the blood and 
other vessels. 
105. The Duodenum. — The first eight or ten 
inches of the small intestine are somewhat larger 
than the remainder, and are called the duode'num, 
because its length is about twelve fingers’ breadth. 
Into this duodenum empty small canals from two 
very important organs, viz., the pan' ere as and the 
liver. 
106. The Pancreas. — The pancreas (Fig. 28), 
Fig. 28.—The pancreas, partly cut away, so as to show the duct, which 
collects the pancreatic juice, and empties it into the duodenum. 
which we call the sweet-bread when we cook it for 
food,* is about six inches long, is shaped somewhat 
* There are three kinds of sweat-breads, viz.: the thyroid-gland, 
or throat sweet-bread, which is tough, almost like India-rubber; the 
pancreas, or belly sweet-bread, which is more tender, and is quite com- 
monly used; and the thymus-gland, or breast sweet-bread, which 
exists only in young animals, wasting away as they grow up. This 
gland is situated just behind the upper portion of the breastbone, at- 
tains its greatest size in human beings at the age of two years, and 
disappears before the sixteenth year. Its use is not known. This 82 
ORGANS OF REPAIR. 
like a pistol, and is situated behind the stomach, 
with the large end, or the breech of the pistol, 
toward the right. It secretes a fluid, called the 
pancreat'ic juice, which has been shown to be the 
chief agent in the digestion of the fatty portions of 
the food. If a quantity of oil be shaken up with pan- 
creatic juice, a white, opaque, creamy fluid is formed, 
in which the drops of oil or fat are not visible any 
more than they are in ordinary milk or cream. Mi- 
croscopic examination, however, shows that the oil 
is not in any way decomposed, but is divided into 
very minute particles, in which condition it can 
be absorbed by the proper channels. In this way 
fat is taken up into the circulating fluids in its own 
proper form, and does not undergo decomposition 
until it reaches other parts of the body, if at all. 
The pancreatic juice also liquefies the nitrogenous 
matters which may have passed the pylorus undi- 
gested, as well as the starches. In fact, it seems to 
be the chief agent in completing the act of diges- 
tion, which has begun in the stomach. 
107. The Liver. — The liver (Fig. 29) is a very 
large organ, the largest and heaviest in the body, 
weighing in a healthy adult from three to four 
pounds, and situated on the right side, protected by 
the lower four or five ribs. It secretes the bile, and 
from its size, and the amount of its secretion, is 
evidently one of the most important organs in the 
body, and yet its precise use is still a matter of dis- 
pute and doubt. 
108. Liver-Sugar.—It was long supposed that the 
only function of the liver was to secrete the bile; but 
gland, taken from calves and lambs, is the most tender and palatable 
sweet-bread of all. INTESTINAL DIGESTION. 
83 
it has been found, in recent years, that it also forms 
a kind of sugar in large amount. The blood which 
enters the liver is found to contain a small amount 
Fig. 29.—Under surface of the liver. 
of sugar, while that which flows away from it, after 
having circulated through it, always contains sugar 
in considerable quantity. Even this fact, well estab- 
lished as it seems to be, is still a subject of dispute 
among experimental physiologists. 
109. The Bile.—The bile is a somewhat glutinous 
fluid, of a rich, golden-red color,* which is dis- 
charged into the duodenum through the same open- 
* When vomiting takes place and lasts for a time, the intestines 
reverse their action, and bile is carried backward through the pylorus 
into the stomach. It is here out of place, and produces extreme nausea. 
Its color is changed by the gastric juice to a greenish yellow. 84 
ORGANS OF REPAIR. 
ing with the pancreatic juice.* It must, therefore, 
become mingled with the food long before digestion 
is completed. The natural inference from this is 
that it has something to do with the process; but 
the digestion of every portion of the food can be 
accounted for in other ways. Nitrogenous matters 
are digested in the stomach, while the fatty mat- 
ters and the starches are digested by the pancre- 
atic juice, assisted, perhaps, by the intestinal juices, 
to be hereafter spoken of. It would appear, then, 
that there is nothing left for the bile to do, and 
that it must be an excrementitious fluid— i. e., that 
it consists of matters which have been separated 
from the blood by the liver because they are hurt- 
ful to the organism, and must, therefore, be ex- 
pelled from the body. This was the ancient view, 
and it seemed to be supported by the fact that, if 
the liver be diseased so that this separation can 
not take place, and the constituents of the bile re- 
main in the blood, jaundice occurs, and, if there is 
no relief, the person dies with all the symptoms 
of poisoning. So far, it seems plain enough that 
the bile has no office to perform in the body, but 
is only secreted to be expelled. But operations 
have been performed on animals in such a way that 
the action of the liver should not be interfered with, 
and yet the bile should not enter the intestine, but 
should be discharged outside the body through an 
artificial opening. Under such circumstances, if 
* As soon as the partially digested food, containing a certain amount 
of gastric juice, passes the opening of the bile-duct, there is a great 
gush of bile into the intestine. It is found that any acid, applied to this 
opening, will produce the same effect. The bile, being alkaline, neu- 
tralizes the gastric juice, which is therefore of no further use, and so 
the digestive process has to be completed by other means. INTESTINAL DIGESTION. 
85 
the bile be simply an excrementitious fluid, its dis- 
charge from the body by one channel rather than 
by another ought not to make any difference in the 
health of the animal. But it is found, on the con- 
trary, that animals treated in this way die with 
every appearance of starvation. Their appetite re- 
mains good, their digestion is not interfered with; 
but, nevertheless, although they eat ravenously, and 
are plentifully supplied with food, they become 
rapidly emaciated and die in about a month. 
These facts show conclusively that the bile has 
some important part to play in the nutrition of the 
body. 
It is found, moreover, by actual chemical exami- 
nation of the excretions, that the bile, although it 
is discharged into the intestine, does not all leave 
the body. It rmist, then, be reabsorbed into the 
circulation. But, if this be so, why does it not give 
rise to symptoms of poisoning, just as if it were 
prevented from leaving the blood in the first place ? 
The only possible answer to this is, that it is some- 
how changed in the intestine, so that w'hen it is 
reabsorbed it is harmless. 
no. The Intestinal Juices.—Besides the bile 
and pancreatic juice, the food meets in the small 
intestine with the intestinal juices proper. Of these 
very little is known with certainty, owing to the 
great difficulty of obtaining them from the living 
animal unmixed with other fluids. The small in- 
testine is lined, however, with a mucous membrane 
containing millions of small tubules and glands, 
which secrete certain colorless alkaline fluids. Of 
these fluids it is both affirmed and denied that they 
possess the property of turning starch into sugar 86 
ORGANS OF REPAIR. 
with great rapidity; but, so far as is known, their 
part in the process of digestion is not important. 
in. Absorption of Food.—If animals are killed 
at different times after the eating of food, and dif- 
ferent portions of the intestine are examined, it is 
found that, while the upper portion of the small 
intestine contains a large amount of partially-di- 
gested food, the lower portion contains the shriv- 
eled remnants of muscular tissue, the husks of 
grains, the woody, indigestible fibers of vegetables, 
etc.; in short, the unappropriated residue of the 
food which has been taken. The great mass of 
what has been eaten has disappeared, and after a 
certain time the whole intestine will be found 
empty. There are two systems of vessels by which 
this absorption of food is accomplished—they are 
the blood-vessels and the lac tea Is* 
112. The Peritonaeum.—To understand the ar- 
rangement of these vessels, it is necessary to know 
something of the peritonce'um. The serous mem- 
brane, which has been spoken of as covering the 
outside of the stomach and intestines, covers to a 
greater or less extent all of the organs contained 
in the abdomen, and also lines the abdominal walls. 
This smooth, satiny membrane is called the peri- 
tonaeum, and it renders the movements of the ab- 
dominal organs possible without discomfort to the 
rest of the organism. Now, the intestine being, as 
has been shown, a long, narrow circular tube, or 
canal, and the peritonaeum passing entirely around 
it, there is a line running the whole length of the 
* Lacteals, from a Latin word meaning milk, because when they 
are filled with the products of digestion they look as if they were filled 
with milk. INTESTINAL DIGESTION. 
87 
intestine, where the membrane becomes double, 
and this double fold is brought together like the 
gathers of a dress, and attached to the spinal col- 
umn. So the intestine is loose in the abdomen, and 
still has an attachment to the spinal column. Be- 
tween these two folds, or, in. other words, within 
the double fold, between the two layers of mem- 
brane, the blood-vessels and lacteal vessels pass to 
the intestine (Fig. 30). 
Fig. 30.—Diagram representing across section of the small intestine, show- 
ing the three layers, and the way in which the blood-vessels pass be- 
tween the two folds of serous membrane (the peritonaeum). 
These vessels grow smaller and smaller and 
more and more numerous as they approach the 
intestine, and, when they at length enter its walls 
and penetrate to the mucous membrane, they di- 
vide into vessels so exceedingly minute as to be 
invisible to the naked eye, and fill the interior of 
the little projections of the mucous membrane, 
which are called villi. 
113. The Intestinal Villi.—The villi are small 
projections on the surface of the mucous mem- 
brane, about a thirtieth of an inch long, and thickly 88 
ORGANS OF REPAIR. 
covering the whole interior of the intestine, there 
being about ten thousand of them to the square 
inch, and about four million altogether (Fig. 31). 
Each villus is covered 
with epithelium, and in 
its interior is a compli- 
cated mass of blood-ves- 
sels, twisted and knotted 
like a bunch of earth- 
worms (Fig. 32). In the 
very center of the whole 
is an open space, which 
is the commencement of 
a lacteal. 
114. The Lacteal 
V essels. — The lad cals 
are only a part of a sys- 
tem of vessels, called the 
lymphatics, which extend 
everywhere throughout 
the body. The lym- 
phatics all begin in a 
way that is not clearly understood, and gradually 
unite to form larger and larger vessels, until their 
contents are finally discharged into the veins and 
mingled with the blood. The fluid found in the 
lymphatics, called lymph, is yellowish, transparent, 
and saltish, and, being derived from the blood, nour- 
ishes the tissues, and takes up and carries away the 
waste. At certain intervals in their course, the 
lymphatic vessels are interrupted by small bodies 
called glands,* varying in size from a hemp-seed to 
Fig. 31.—Section of the mucous mem- 
brane of the small intestine, show- 
ing two villi, and several secreting 
tubes or follicles; also lacteals, 
blood-vessels, and, at the bottom, 
the muscular layer. 
* The lymphatic glands are the bodies that sometimes undergo INTESTINAL DIGESTION. 
89 
an almond, into which the vessels enter, and from 
which they emerge. Whether they actually pass 
through the gland, or whether 
one vessel ends in it and another 
begins, is still a subject of dis- 
cussion. But the lymphatic ves- 
sels all over the body have great 
absorbing power, taking up in- 
discriminately foods, poisons, or 
the waste of used-up tissues. 
The lacteals, then, are that 
portion of the lymphatic system 
which is connected with the 
small intestine, and all the lac- 
teals from the villi gradually 
unite to form a vessel called the 
thorac'ic duct, about as large as a 
goose-quill, which passes up 
close to the spine, and empties 
into a large vein very near the 
heart.* 
115. The Portal Vein.—The 
blood-vessels which absorb the food from the intes- 
tines are veins, and they unite with the veins from 
the stomach, pancreas, and spleen, to form one large 
vein, called the portal vein, which enters the liver, 
so that all the blood from the digestive apparatus 
Fig. 32.—Intestinal villus, 
showing the epithelial 
cells outside, the blood- 
vessels, and the begin- 
ning of a lacteal vessel. 
slow inflammation in persons of a scrofulous tendency, forming hard 
lumps or abscesses in the neck. 
* Many years ago, a man named Calvin Edson became extremely 
emaciated without any known cause. He was exhibited for a long 
time as “ the living skeleton.” After his death it was found that his 
thoracic duct was completely obstructed, so that none of the contents 
of the lacteals could pass into the blood. He died, therefore, of fat- 
starvation—i. e., a complete or almost complete deprivation of fat. 90 
ORGANS OF REPAIR. 
passes through the liver before it enters the general 
circulation. 
116. The Chyle.—The villi, then, projecting as 
they do into the interior of the small intestine 
through its entire length, are continually bathed, 
during digestion, in the nutritious fluid which other 
organs have prepared for absorption. They float 
and sway about in this fluid, and suck it up as the 
roots of a tree get their sustenance from the soil,* 
and the blood-vessels probably have quite as much 
to do in the process as the lacteals. The latter ab- 
sorb mostly the fatty matters in the cream-like form 
to which they have been reduced by the pancreatic 
juice. As the walls of the vessels are thin and 
transparent, the creamy contents, called the chyle, 
show through, and hence arises the white appear- 
ance during digestion which has given them the 
name of lacteals. 
117. Changes in the Blood during Digestion.— 
* The latest researches seem to show that the lacteal begins in the 
interior of the villus as a sort of hollow space, without any special 
wall of its own, and that around this space there are small fibers of in- 
voluntary muscular tissue. It is believed that, during the process of ab- 
sorption, these muscular fibers contract at regular intervals. The effect 
of the contraction would be to pull down the top of the villus toward the 
base, and thus diminish the size of the hollow space above referred to, 
and empty its contents into the lacteal vessel. When the fibers relax, 
and the hollow space expands to its original dimensions, the fluid 
which has been forced into the lacteal is prevented from being sucked 
back again by the valves, with which all lacteal vessels are provided. 
The space is therefore filled again by the fluids which surround the 
end of the villus in the intestinal canal. In this way, by the alternate 
and regular contraction and relaxation of these minute muscular fibers, 
the villus acts like a suction-pump, and the intestine may be looked 
upon as lined with millions of microscopic suction-pumps, which work 
away during digestion, pumping the contents of the intestine into the 
bcteals, by which they are discharged into the blood. INTESTINAL DIGESTION. 
As absorption goes on, the blood becomes more 
and more loaded with fatty matters, which can 
easily be recognized in it in the form of minute oily 
drops, but all of this blood passes through the lungs 
before it goes to the rest of the body. In its pas- 
sage through the lungs, the fatty matters disappear 
in some way, not exactly understood, and the blood 
which comes away from the lungs contains none. 
After a time, however, as digestion progresses, the 
blood is so heavily charged with these oily matters 
that they can not all be decomposed, and a portion 
remains and is sent in the general circulation all 
over the body. If blood be drawn from a man or 
other animal at this time and allowed to stand, 
there will be a yellowish, creamy layer on its top. 
Presently, however, the fat begins to disappear, 
as digestion approaches its close; the amount in 
the blood gradually diminishes, until it is entirely 
gone, the lymph in the lacteals becomes once more 
a transparent fluid, and digestion is complete. 
118. The Spleen.—At the left extremity of the 
stomach, just under the ninth, tenth, and eleventh 
ribs, is an organ which is to this day a great puzzle 
to physiologists. It is called the spleen, and is about 
five inches long, four wide, and an inch thick. It 
is reddish in color, soft and pulpy in texture, with 
a very tough and strong fibrous covering. It re- 
ceives its blood from a very large artery, and its 
vein, which carries away the blood from the organ, 
joins the portal vein, so that the blood from the 
spleen, like that from the other organs of digestion, 
passes through the liver, before it reaches the heart. 
The spleen is large in well-fed animals, and very 
small and shrunken in starved ones, while in some 92 
ORGANS OF REPAIR. 
cases of disease, such as fever and ague, it reaches 
the enormous weight of twenty pounds, and forms 
an immense hard tumor in the left side. 
The facts just stated would seem to imply that 
the spleen has some important office to perform in 
digestion, but what that office is no one has been 
able to discover.* It is a singular fact that the 
spleen may be entirely removed from animals with- 
out permanent injury to their health. This opera- 
tion has often been done to dogs, and the animal 
recovers from the wound very rapidly. He shows, 
however, an enormous increase of appetite, usually 
gains considerable flesh, and acquires an unnatural 
ferocity of disposition. These things, however, do 
not seem to indicate that any particular function 
has been lost to the body, and the uses of the spleen 
are still a subject of earnest investigation. 
* The most reasonable theory about the spleen at present seems to 
be that it has something to do with the destruction of old and worn- 
out blood-corpuscles and the formation of new ones. CHAPTER V. 
THE BLOOD. 
X19. The Blood.—After the nutritious portions 
of the food have been taken into the blood, they 
pass through the lungs before they go into the 
general circulation. Before we consider the respi- 
ration, however, it is necessary to know something 
of the circulating fluid. 
The blood is a thick, opaque fluid, varying in 
color in different parts of the body from a bright 
scarlet to a dark purple or even almost black. It 
has a somewhat viscid feel, a faint odor peculiar to 
itself, and a saltish taste. 
120. The Red Blood-Corpuscles.—If a drop of 
blood be placed under the microscope,* immense 
numbers of small bodies will be seen, which are 
called the blood-corpuscles (Figs. 33 and 34). They 
are very minute, averaging only -g-gVir of an inch in 
diameter, and are flattened in their shape. They 
may be described as looking like a cylindrical ring, 
the center of which has been filled up, but not quite 
to the level of the border, so that there is a slight 
depression on each flattened side. Taken singly, 
* Prick the end of the finger with a pin. The most minute drop 
of blood is sufficient. Put it on a glass slide under a thin glass cover, 
and place it under a microscope. 94 
ORGANS OF REPAIR. 
these bodies, called the red blood-corpuscles, are of a 
light amber color, but in a large mass they give 
the characteristic red col- 
or to the blood. They vary 
somewhat in size in differ- 
ent animals, those of the 
monkey approaching most 
nearly to those of the hu- 
man being. In birds, rep- 
tiles, and fish, they are 
very much larger, and in- 
stead of being circular are 
oval (Fig. 35).* They also 
have a distinct nucleus. 
It is mainly by these microscopical differences that 
the blood of different animals can be distinguished 
Fig. 33.—Human blood-corpuscles, 
including two white ones. 
Fig. 34.—Human blood-corpuscles (highly magnified). From a photograph. 
* The blood-corpuscles of the camel tribe are also oval, but smaller 
than those of birds. THE BLOOD. 
95 
from that of man, as is sometimes necessary in 
trials for murder. 
121. The White Blood-Corpuscles.—The blood 
also contains white corpus- 
cles in the proportion of one 
white corpuscle to three 
hundred red ones. They 
are larger than the red, are 
perfectly colorless, and glo- 
bular in their form. The 
white corpuscles, under 
proper conditions, are seen 
to be continually changing 
their form, almost like liv- 
ing animals. There have 
been many speculations as 
to their office in the body, but nothing definite has 
been ascertained. In certain diseases, however, 
they are found to increase enormously in number, 
and some of these diseases are among the most 
dangerous and difficult to treat of any the physi- 
cian meets with. 
Although the blood-corpuscles are so very mi- 
nute, they exist in such enormous numbers that 
they are estimated to compose half the mass of 
the blood. 
122. The Plasma. — The fluid portion of the 
blood, in which these small bodies float, is called 
the plasma. It is almost colorless, quite transpar- 
ent, and is nine tenths water. Its two most im- 
portant ingredients are albumen and fibrin.* The 
RED 
WHITE 
Fig. 35.—Blood-corpuscles of the 
frog. 
* It is now believed that fibrin does not exist, as such, in fluid 
blood, but that there are certain substances (known as fibrino-plastin 
or paraglobulin, fibrinogen, and fibrin-ferment) which, by their inter- 96 
ORGANS OF REPAIR. 
former of these is chiefly concerned in nutrition, 
and the latter brings about the remarkable phe- 
nomenon known as coagulation. The plasma also 
contains various compounds of lime, soda, mag- 
nesia, etc., which have their own functions to per- 
form in the nourishment of the body. 
123. Coagulation of the Blood. — If blood be 
drawn from the living body, it very soon under- 
goes coagulation. This is due to its fibrin (or fibrin- 
factors) ; but the cause of the change is very im- 
perfectly understood. After the blood has stood 
for a few minutes outside the blood-vessels, it at 
first becomes less fluid and assumes somewhat the 
appearance of jelly. Shortly the fibrin begins to 
contract and occupy a smaller space, gradually 
squeezing out the portion of the blood which still 
remains fluid. This mass which separates from the 
rest of the blood is called the clot, and the remainder, 
or still fluid portion, is called the serum. The con- 
traction of the clot continues for several hours, 
until it forms quite a firm mass of a deep-red color, 
the remaining fluid being transparent and nearly 
colorless. 
The red color of the clot is due to the fact that 
the red corpuscles become entangled in the coagu- 
lated fibrin, and, being semi-solid in consistency, 
they remain there and are not pressed out with the 
serum. It will be noticed that the scrum is not the 
same as the plasma. The latter includes the fibrin 
(or fibrin-factors), while the former is without it. 
124. Coagulation under Varying Conditions.—It 
is found that the blood coagulates more rapidly in 
action, produce fibrin, and so cause coagulation. The evidence for 
this view is of too abstruse a nature to be given here. THE BLOOD. 
97 
thin layers than in a large mass; in a vessel or on a 
surface which is rough than in one which is smooth. 
For this reason the blood flows longer from a 
smooth cut in the body than from a wound with 
torn and ragged edges. In the latter case the blood 
coagulates very rapidly and stops the hemorrhage. 
But the coagulation of the blood takes place not 
only outside the body, but, under similar circum- 
stances, inside, though not always with equal ra- 
pidity. If a vessel bursts inside the body, and 
blood escapes into the tissues around it, coagula- 
tion takes place after a short time; and this occurs 
even inside the blood-vessels, if there be any ob- 
struction to the circulation. If an artery or vein 
be compressed by a string or wire or finger, the 
blood will soon coagulate in the vicinity of the 
pressure. These facts have suggested the means 
used by surgeons to stop the flow from a bleeding 
wound, and will be referred to again. 
125. Total Amount of Blood.—The total amount 
of blood in the human body is believed to be about 
one twelfth of the whole zveight of the individual. 
Thus, in a man who weighs one hundred and fifty 
pounds there will be about thirteen pounds of blood, 
or somewhat more than a gallon and a half. 
126. Oxygen in the Blood.—This rich, nutritious 
fluid is forced to all parts of the body in a way here- 
after to be described, carrying food to exhausted 
tissues and removing the used-up matters. A large 
part of the material necessary for the growth and 
nourishment of the body is taken in through the 
digestive organs; but there is a gas absorbed by 
the blood, in its passage through the lungs, which 
is even more necessary to life than food. This gas 98 
ORGANS OF REPAIR. 
is oxygen, which constitutes about one fifth of the 
atmosphere, and is essential to the life of all animals, 
probably without exception. We can live for days 
without food, but we can not live ten minutes with- 
out oxygen. Even water-animals are not exempt 
from this law; for fish extract the air, which is in 
solution in the water, by passing it through their 
gills. If a dish of water containing a fish be placed 
under the receiver of an air-pump, and the air be 
exhausted from it, the fish will be as surely drowned 
as a man would be if held under water. This is the 
reason why fish which are kept as pets in aquaria 
need fresh water continually. If a jet of water be 
kept falling into the vessel in which they live, so as 
to drag down bubbles of air, the water need never 
be changed, except for cleanliness. 
127. Varying Color of the Blood.—The blood 
which enters the lungs is very dark, and sometimes 
almost black. When it has passed through the 
lungs, and flows away, it is of a bright scarlet. It 
has lost certain substances and gained others during 
this passage, and this beautiful and surprising alter- 
ation is produced by what is called the process of 
respiration. CHAPTER VI. 
RESPIRATION. 
128. Respiration a Complicated Process. — At 
first sight, the process of respiration is a very sim- 
ple one, consisting merely in the inspiration and 
expiration of air. In reality, however, it is compli- 
cated—certain very essential parts of it going on 
without our consciousness, like so many of the phe- 
nomena of digestion. The organs mainly concerned 
in the acts of respiration are the lungs; but there 
are certain additional organs, whose functions, if not 
absolutely necessary, are certainly important. 
129. The Nasal Passages. — The air, before 
reaching the lungs, goes through several passages, 
lined throughout with mucous membrane. The 
human being can breathe through either the nose 
or the mouth ; but in some animals (the horse, for 
instance) respiration only takes place through the 
nose, and, if this be closed, suffocation follows. The 
external openings of the nose are guarded by short, 
stiff hairs, which grow just inside the nostrils, and 
which serve to purify the air somewhat, as it passes 
through them, by catching and retaining particles 
of dust. The interior of the nose is so formed that 
it is not a large, open, free passage, but has a num- 
ber of projecting bones, running lengthwise along 100 
ORGANS OF REPAIR. 
its walls, which are covered with moist membrane 
and present an extensive mucous surface to attract 
particles from the air. If we breathe through the 
mouth, on the other hand, the air goes directly to 
the throat, and the cavity of the mouth is so large 
that the purifying effect of the moist membrane is 
hardly perceived. This shows how much better it 
is to breathe always through the nose; for the air, 
undoubtedly, in this way, is rid of many impurities; 
and physicians habitually, and almost unconsciously 
to themselves, keep their mouths shut as much as 
possible when they are exposed to a contagious 
disease. 
From the nose the air arrives at the throat, and 
thence it passes into the windpipe, or trachea, 
through a small opening called the glottis. 
130. The Trachea.—The tra'chca (Fig. 36) is a 
tube about four and a half inches long and an inch 
wide, which divides at its lower extremity into two 
smaller tubes called bronchi, one of which goes to 
each lung. It is mainly fibrous in its structure, 
and it is kept open to its full extent by a number 
of rings of cartilage, placed at a short distance 
apart through its whole length. The trachea is 
situated in the neck just in front of the oesophagus, 
and as these stiff rings might press backward on 
the oesophagus, and thus interfere with the process 
of swallowing, they do not pass completely around 
the trachea, but are lacking in the part next the 
oesophagus, comprising about one third of the 
whole circumference of the tube. At the upper 
extremity of the trachea is the lar'ynx, or the organ 
of voice, which is essentially a triangular-shaped 
box of cartilage, the lower end opening freely into RESPIRA TION. 
101 
the trachea, and the upper being closed by muscles 
and membranous tissues, with the exception of the 
opening of the glottis. 
Fig. 36#—Larynx, trachea, and bronchi, showing the manner of division, 
and the rings of cartilage. 
131. The Glottis.—The glottis is a slit-shaped 
opening, a little less than an inch long, extending 
from before backward and from above downward, 102 
ORGANS OF REPAIR. 
not being-, in other words, either perpendicular or 
horizontal in the throat, but shelving toward the 
rear. The front extremity is at the base and back 
of the tongue, and the opening itself is bounded at 
the sides by two firm, fibrous, strong, pearly-white 
membranes, called the vocal chords, by the vibration 
of which sound is produced. These vocal chords 
can be separated to the extent of half an inch, or 
brought together so as to touch, by the muscles 
which are attached to the back part of the larynx. 
The production and modulation of the voice will 
be treated of hereafter. 
At the base of the tongue, springing upward 
just above the forward end of the glottis, is a stiff 
piece of cartilage, shaped like a leaf with a rounded 
end. This is called the epiglottis, and probably 
performs two functions, viz., that of protecting the 
glottis from food or other substances during the 
act of swallowing, and that of directing the column 
of expired air up toward the roof of the mouth 
or throat, and so aiding in the modulation of the 
voice. 
132. The Lungs.—The essential organs of res- 
piration are the lungs, which are two in number and 
fill nearly the whole cavity of the chest, a portion, 
however, being occupied by the heart and large 
blood-vessels. The lungs are very light in propor- 
tion to their size, and in animals they are common- 
ly called “ the lights.” They weigh together only 
about two pounds and a half, and easily float in 
water. In small children they are of a beautiful 
pinkish color, but in older persons they become 
slate-colored, and have black spots scattered here 
and there over their surface. RESPIRA TION. 
103 
133. Minute Divisions of the Lungs.—After the 
trachea divides into two bronchial tubes, one of 
which goes to each lung, these bron- 
chial tubes continue to subdivide in- 
to smaller and smaller tubes, all the 
branches diverging widely from 
each other, until their diameter is 
diminished to about -fa of an inch. 
At about this point the cartilage 
rings disappear, but the tubes still 
divide until the smallest are only 
of an inch in diameter. At the very 
ends of the smallest tubes, there is 
an enlargement about of an inch 
in diameter, called a pulmonary lobule 
(Fig. 37). It constitutes a small cav- 
ity, into which dip little partitions, that do not meet 
each other, but create minute hollow spaces around 
the sides of the lobule, called pulmonary 
vesicles. These are about of an inch 
in diameter, and are the smallest divis- 
ions of the lung. 
134. The Lining Membrane of the 
Lungs.—All these tubes and passages, 
down to the most minute, are lined 
with a delicate mucous membrane, 
which has this remarkable peculiarity. 
The little epithelial cells with which all 
mucous membranes are covered, have 
in this situation what are called cilia at 
their ends (Fig. 38). That is to say, 
each cell has at its tip a fine, hair-like 
lash, which keeps in constant motion, 
as long as the person lives, and for some time 
Fig. 37.—Section of 
a pulmonary lob- 
ule, showing its 
division into pul- 
monary vesicles. 
Fig. 38.—Cilia- 
ted epithelium 
from a small 
bronchial tube. 
The small 
round cells at 
the bottom are 
young ones. ORGANS OF REPAIR. 
104 
after he is dead. If a piece of the mucous mem- 
brane from a frog’s throat be snipped off with a 
pair of scissors, and then doubled with the natu- 
rally outer side outward, and placed under the mi- 
croscope, this incessant motion of the cilia may be 
easily seen. It is an experiment well worth trying, 
for it is an astonishing and beautiful sight even to 
one who has often seen it. The cilia, although 
they are so delicate in their structure, are so in- 
numerable and act in such perfect concert, that 
they keep up a constant current toward the outside 
of the body. They probably aid in the expulsion 
of the foul gases which the blood leaves in the 
lungs. 
135. Asthma. — The smaller bronchial tubes, 
which have no rings of cartilage, are nevertheless 
surrounded by involuntary muscular fibers. When, 
in consequence of disease, these fibers contract 
strongly, they diminish the caliber of the tubes, and 
render it very difficult sometimes for the sufferer 
to get air through them in either direction. This 
condition gives rise to great distress and a sense 
of suffocation, and is called asthma. 
136. The Blood-Vessels of the Lungs.—Between 
the pulmonary vesicles run the small blood-vessels 
immediately under the delicate mucous membrane, 
so that the blood comes almost in contact with the 
air that we breathe. They surround the vesicles 
completely, and it is in this part of the lung that 
the great changes take place in the blood during 
respiration. 
137. The Outer Covering of the Lungs.—The 
outside of the lung is covered by serous membrane, 
and so is the inside of the chest-wall. This renders RESPIRATION. 
105 
the movements of the lung painless and easy. This 
membrane is called the pleura, and when it becomes 
inflamed, in the disease known as pleurisy, respira- 
tion becomes excessively painful. 
138. Inspiration.—As the cavity of the chest is 
enlarged, the air already in the lungs is rarefied, 
and the external atmospheric pressure forces air 
in to fill the organs. We have already stated that 
the ribs are so shaped, and so connected with the 
spine behind and the sternum in front, that when 
they are raised up toward the shoulders the sides 
move outward, and the sternum moves forward. 
This motion of the ribs is caused partly by power- 
ful muscles attached to 
their external surface all 
the way down the chest, 
and partly by short mus- 
cles which pass between 
the ribs from the lower 
edge of each one to the 
upper edge of the one 
just below it. 
But, in addition to its 
expansion toward the 
front and sides, the cav- 
ity of the chest is en- 
larged in a downward 
direction by the con- 
traction of the diaphragm 
(Fig. 39). This muscle 
has a strong, flat, ten- 
dinous center, from every side of which strong 
muscular fibers pass to the walls of the chest. It 
separates the chest from the abdomen, and while 
Fig. 39.—Diagram illustrating the vary- 
ing position of the diaphragm during 
respiration. 106 
ORGANS OF REPAIR. 
the muscular portion of it is attached to the lower 
ribs, the spine and the very end of the breastbone, 
the center rises much higher in the chest, so that 
it has the shape of a vaulted roof, on top of which 
are the lungs and heart, and underneath the stom- 
ach and liver. Of course there are passages through 
it for the blood-vessels and nerves, but these open- 
ings are so guarded that the diaphragm forms a 
tight partition. Now, as the center of the diaphram 
rises so much higher than the sides, it is very evi- 
dent that a contraction of the muscular fibers will 
pull the center downward, and so increase the ca- 
pacity of the chest. And this is what actually 
occurs at every inspiration. When this contrac- 
tion takes place spasmodically, the air is drawn 
into the lungs with a sudden impulse, and we call 
it hiccough.* 
139. Expiration. — Inspiration then involves a 
contraction of many muscles, and they act with a 
great deal of force, for they have to lift the atmos- 
phere, which is pressing on the outside of the 
chest with a force of fifteen pounds to the square 
inch. By this simultaneous contraction, the ribs 
are drawn out of their natural position—i. e., they 
are drawn upward into a position which they never 
would assume if left to themselves. By the elastici- 
ty of their cartilages and other tissues attached to 
them, they tend to return to their former position 
as soon as the force which has drawn them out of 
* Hiccough, being due to a spasmodic action of the diaphragm, may 
be stopped by any means that tends to control the spasm. The easiest 
method is to put the diaphragm on the stretch, as follows : prolong the 
act of expiration as much as possible, and at the end make a forcible 
expiration; then inspire slowly and take as full an inspiration as pos- 
sible. It is rare that a second trial will be necessary. RESPIRATION. 
107 
it ceases. The diaphragm, also, when contraction 
stops, tends to recover its former arched shape. 
The lungs also contain, in addition to the elements 
already mentioned, a large amount of elastic fibers, 
interlaced with the other tissues in every direction. 
These, too, as soon as the pressure which has 
stretched them ceases, tend to return to their for- 
mer condition. This elasticity of the different 
organs concerned in the act of respiration, then, 
brings the chest and lungs back to the condition in 
which they were before inspiration began. This 
is the ordinary act of expiration. 
140. Relative Force of Inspiration and Expira- 
tion.—As we usually breathe, then, the act of inspi- 
ration is an active one, requiring effort and power- 
ful muscular contraction, while the act of expira- 
tion is passive, and is accomplished by the elasticity 
of the tissues.* 
Under other conditions, however, the act of 
expiration may be more powerful than that of in- 
spiration. There are strong muscles connected 
with the chest in such a way as to act in opposition 
to the muscles of inspiration, and make the cavity 
of the chest smaller than it ordinarily is. It is by 
the active contraction of these muscles that we pro- 
duce what is called a forced expiration, which has 
been estimated by careful observers to be one third 
more powerful than a forced inspiration. 
141. Amount of Air respired with Each Breath. 
* The outer surface of the lungs is kept in contact with the chest- 
walls by atmospheric pressure. If the chest-wall be punctured, so 
that the air-pressure is the same both outside and inside of the lung, 
the elasticity of the organ is such that it immediately collapses, driving 
out all the air from its interior. ORGANS OF REPAIR. 
108 
—The amount of air taken into the lungs with each 
inspiration is about twenty cubic inches. Now, the 
entire capacity of the lungs varies in different per- 
sons from one hundred and fifty to two hundred 
and fifty cubic inches or even more. So that with 
each breath, a very small amount, generally not 
one tenth, of the air in the lungs is changed. It is 
even estimated that after the most forcible expira- 
tion possible, at least one hundred cubic inches of 
air will remain in the chest of a man of medium 
size, which can not be expelled. In ordinary breath- 
ing, therefore, only the air in the larger bronchial 
tubes can pass in and out of the lungs. But the 
changes in the blood must be produced at the ex- 
treme end of the finest tubes in the pulmonary 
vesicles. So the question arises, How does the air 
get to the vesicles ? 
142. How the Air in the Lungs is changed.—In 
the first place, the law of the diffusion of gases comes 
in play. When two gases come together, they tend 
to mingle with each other until they finally occupy 
equally the whole of the vessel or other confined 
space in which they may be. After the mixture, 
each gas will be found in the same proportion in 
every part of the vessel. Now, the air in the pul- 
monary vesicles and smallest bronchial tubes is 
heavily loaded with carbon dioxide (carbonic acid), 
while that which is drawn in with inspiration is rich 
in oxygen. These two gases, then, carbon dioxide 
and oxygen, are constantly being diffused through- 
out the whole of the lungs. In the second place, 
the cilia, which have already been described, being 
in constant motion, keep up a current of the foul 
air from the pulmonary vesicles along toward the RESPIRATION. 
109 
larger bronchi and trachea, and fresher air keeps 
constantly pressing in to fill the place of what has 
been in this way removed. Thus, in the smallest 
bronchial tubes, there are always two currents of air 
passing each other in opposite directions : one, im- 
mediately next the mucous membrane, being a thin 
layer moving outward; and the other, in the center 
of the tube, moving inward (Fig. 40). So that the 
air in the larger bronchi and trachea is changed 
periodically by the acts of 
inspiration and expiration, 
while the circulation of 
the air in the small bron- 
chial tubes and pulmonary 
vesicles is continuous. 
143. Amount of Air re- 
spired daily.—The amount 
of air taken in with every inspiration is about twen- 
ty cubic inches. The average number of respira- 
tions per minute is eighteen. This is a matter 
which varies very much with the individual. Chil- 
dren and women breathe somewhat more rapid- 
ly than men ; but taking eighteen as the average, 
the quantity of air breathed per minute is three hun- 
dred and sixty cubic inches, or about one fifth of a 
cubic foot. In an hour, then, we use about twelve 
cubic feet of air, and in a day nearly three hun- 
dred cubic feet. This amount is increased by every 
muscular exertion, and also by the curious fact that 
the ordinary respiration does not seem to be alto- 
gether sufficient for the needs of the body, and every 
now and then we draw a deeper breath than the 
average. This occurs usually about once in every 
five or six acts of respiration. Considering the in- 
Fig. 40.—Imaginary section of a 
small bronchial tube, showing 
the influence of the cilia in pro- 
ducing an outward current of air. 110 
ORGANS OF REPAIR. 
crease in the amount of air respired at each long 
breath, and the increase of rapidity of respiration 
due to slight causes during the day, it is estimated 
that an adult really respires about three hundred 
and fifty cubic feet of air per day. 
144. Changes produced in the Air by Respira- 
tion.—When the air enters the lungs it contains 
nearly 21 per cent of oxygen and 79 per cent of ni- 
trogen, with about one twentieth of one per cent of 
carbon dioxide, a little watery vapor, and a trace of 
ammonia. 
If the air be collected at expiration, after having 
undergone the changes in the lungs, we find the 
following: 
1. It has lost oxygen. 
2. It has gained carbon dioxide. 
3. It contains more watery vapor. 
The watery vapor in the expired air is not or- 
dinarily visible, but in cold weather, when it be- 
comes condensed, it can be very plainly seen. The 
whole amount of water passed away daily in the 
breath of a man has been carefully estimated, and 
found to average about one and one sixth pound 
avoirdupois. 
145. Former Theory about the Formation of 
Carbon Dioxide.—Out of the four cubic inches of 
oxygen taken into the lungs with each inspira- 
tion, one cubic inch disappears. The carbon dioxide 
which is exhaled from the lungs consists of carbon 
and oxygen united in certain proportions, and it 
used to be supposed that the carbon in the blood 
united with the oxygen of the air in the lungs 
themselves, forming carbon dioxide, and that in 
this way the carbon, released by the wear and tear RESPIRA TION. 
of the body, was got rid of. Now, the process of 
combustion in a flame of any kind consists in this 
same change, viz., the union of the carbon and hy- 
drogen of the oil or other inflammable substance 
with the oxygen of the surrounding air, forming 
carbon dioxide and water, and giving out heat 
during the process. So it was for a long time 
thought that the lungs were a sort of furnace in the 
body, where the carbon and hydrogen of the blood 
were burned, so to speak, and the products of com- 
bustion exhaled, while the heat occasioned by the 
process kept up the warmth of the body. This was 
a beautiful theory, but it is found not to be warrant- 
ed by the facts. 
There is more oxygen absorbed in the lungs, with 
every respiration, than is exhaled in the carbon di- 
oxide and watery vapor taken together. This fact 
of itself disproves the above theory, for it shows 
that a portion of the oxygen disappears in the 
lungs, or is carried away by the blood. 
146. Organic Matter in the Breath. — Besides 
the carbon dioxide given off in the expired air, 
there is a certain amount of organic matter, con- 
taining nitrogen, which gives the breath a slight 
but peculiar odor. Where many persons are 
breathing in a badly ventilated room, this organic 
matter accumulates, and imparts to the atmosphere 
that odor which we all recognize as peculiarly op- 
pressive and close. 
147. Changes in the Blood during Respiration. 
—The blood undergoes changes in its passage 
through the lungs which correspond to the changes 
in the air. In the first place, it is altered in its 
color. As it enters the lungs, it is of a deep bluish ORGANS OF REPAIR. 
112 
purple, almost black; as it emerges, it is of a beau- 
tiful and most brilliant scarlet. On chemical ex- 
amination, to determine the cause of this remark- 
able change, it is found that the blood which comes 
away from the lungs contains more oxygen and 
less carbon dioxide than that which enters them. 
Additional proofs that the formation of carbon di- 
oxide does not take place by direct combination 
in the lungs are the facts that the venous blood, 
before it enters the lungs, is deeply charged with 
carbon dioxide already formed, and that the blood 
which comes away from the lungs contains oxygen 
in free solution. 
The brilliant color, which is the result of this 
change in the blood, has not yet been satisfactorily 
accounted for. It has been proved that the oxy- 
gen and carbon dioxide are carried by the blood- 
corpuscles, and not by the plasma, and the change 
of color in the blood is entirely due to the change 
in those minute bodies. They have been said to 
change their shape and become more globular in 
one case than in the other, but the attempts to ex- 
plain the difference of color have not yet been en- 
tirely successful.* 
148. Where the Carbon Dioxide is formed.—If 
the carbon dioxide is not formed in the lungs, 
then where does it come from ? Experiments of 
the most ingenious kind have been performed to 
determine this question, and they are too long to 
* The coloring-matter of the red corpuscles is called hemoglobin. 
It is found that this substance, when united with an excess of oxygen, 
forming oxyhsemogiobin, has a bright scarlet color, and, when the 
amount of oxygen is greatly reduced, is of a dark purple. But this 
does not explain much. RESPIRATION. 
113 
mention in detail. But it has been conclusively 
shown that most of the carbon dioxide is formed 
in the tissues in all parts of the body, during the 
processes of nutrition. And even here it is not 
produced by a direct combination of the oxygen 
with the carbon, for the exhalation of carbon di- 
oxide will continue for a considerable time in an 
atmosphere of hydrogen, where of course there is 
no oxygen furnished to the tissues. The carbon 
dioxide, then, is formed by decomposition of the 
tissues, and the oxygen is used by them to build 
themselves up again.* The amount of carbon di- 
oxide given off in the breath has been found to be 
somewhat less than one cubic inch, or about four- 
teen cubic feet per day, weighing about a pound 
and a half, and representing waste of the organism 
to about this amount. 
149. Composition of Air.—Air being so essential 
to life, it is evidently important to have it as pure 
as possible. It must contain enough oxygen, so 
that with each respiration the temporary needs of 
the body may be satisfied, and should contain no 
substances which are injurious to life or health. 
Now, the air normally contains about four parts 
of nitrogen to one of oxygen. It always contains 
a small amount of carbon dioxide, and a variable 
quantity of watery vapor.f It is also never found 
* It will be understood that the place of the carbon which is lost to 
the body in the carbon dioxide which passes off by the lungs, is sup- 
plied by the fresh material taken in with the food. 
+ This watery vapor is a very necessary constituent of the air. Out- 
of-doors the amount of it is regulated in ways beyond our control ; 
but in-doors, unless special care is taken, the air may be so dried by 
artificial heat, that when respired it will absorb more than the ordinary 
amount of moisture from the mucous lining of the lungs. Then the ORGANS OF REPAIR. 
114 
entirely free from impurities, such as other gases 
than those named, in small quantity, and minute 
floating particles of matter, which we group to- 
gether under the common name of dust. 
It has been shown, however, that the breathing 
of animals is continually removing oxygen from the 
air and increasing the amount of carbon dioxide. 
Now, carbon dioxide is a poison to animals, and 
if inhaled in large amount produces almost imme- 
diate unconsciousness and death. It is for this rea- 
son that it is being constantly rejected from the 
body. If this process of removing oxygen from 
the air and adding carbon dioxide to it were to 
go on indefinitely, it is evident that after a time 
the one would be so much reduced in amount, 
and the other so much increased, that animals 
would die of carbon-dioxide poisoning—i. e., of 
asphyxia. 
150. Respiration of Plants.—This danger is 
guarded against in the outer atmosphere by the 
constant absorption of carbon dioxide by plants. 
All plants, through their leaves, decompose car- 
bon dioxide into its original parts, carbon and 
oxygen. The carbon they appropriate for their own 
nourishment, and the oxygen they return to the at- 
mosphere. Thus the respiration of plants is exactly 
the reverse of that of animals. The latter absorb 
oxygen and give out carbon dioxide, and the for- 
mer absorb carbon dioxide and give out oxygen. 
mucous membrane becomes dry, there is an increased flow of blood to 
the part, and, if the dryness of the air is not remedied, inflammation 
may result—i. e., a catarrh. For this reason a vessel of water should 
always be kept on the top of a heated stove or furnace, that its evapo- 
ration may insure sufficient moisture in the air to prevent injury to the 
lungs and throat. RESPIRA TION. 
115 
By this never-ending interchange the proportions 
of oxygen and carbon dioxide in the atmosphere 
are kept about the same. 
151. Contamination of the Air in Houses.—In- 
doors, however, there is no opportunity for this 
self-purification. Even if a few plants are kept in 
the house, the amount of carbon dioxide they con- 
sume is very little, and the effect they are able to 
produce toward purifying the room can not be com- 
pared with that of the immense stretches of forest 
and plain out-of-doors. Moreover, the amount of 
carbon dioxide in houses is increased by combus- 
tion. A five-foot gas-burner throws out as much 
carbon dioxide as five men. The unhealthiness of 
a closed room is also increased by the organic mat- 
ter of the breath, which is very poisonous.* The 
odor of this matter is perceptible in a room long 
before the accumulation of carbon dioxide reaches 
a point when it is likely to be injurious. It is, there- 
fore, to be looked upon as by far the most danger- 
ous impurity in the atmosphere of an occupied 
room. 
152. Ventilation.—In order to forestall any evil 
result from such impurities, the air of a room should 
be changed frequently enough to prevent the odor 
of this organic matter from being perceptible. This 
usually requires some special attention, and is called 
ventilation. In warm weather, all that is necessary 
is to open the doors and windows and allow the air 
to circulate freely through the house. But in cold 
* The composition of this organic matter is not known. It is given 
off in such small quantity that the chemists have never been able to 
analyze it. It putrefies rapidly after it has left the body, and then be- 
comes very offensive. 116 
ORGANS OF REPAIR. 
weather more care is required. A fireplace, with 
an open fire, is an excellent means of drawing out 
the foul air—sending it up the chimney, and so out 
of the house. The fresh air, to supply the place of 
what has been thus removed, may come in through 
cracks in the windows and doors. But the fresh 
air admitted in this way in cold weather, being 
heavier than warm air, falls and sweeps along the 
floor. This is very dangerous, for few people 
can endure a cold draught on the feet and ankles, 
while the rest of the body is warm, without tak- 
ing cold. Moreover, the smallness of the apertures 
through which the air comes increases the ra- 
pidity of the current. It is better, therefore, to let 
in the fresh air through a special opening, so ar- 
ranged that the cold air shall not immediately fall 
to the floor. This can be done cheaply and effect- 
ively by raising the lower sash of the window about 
four inches, and putting underneath it a board, fit- 
ted to close the opening tightly between the sash 
and the sill. There will then be a long, narrow 
opening between the upper and lower sash, through 
which air will enter in a current directed upward 
toward the ceiling, and, before it descends, its mo- 
mentum will be so much diminished that it will not 
create a draught. In very cold places, where double 
windows are used, the same result may be obtained 
by raising the lower outer sash a little, and lowering 
the upper inner one. The best way, however, is to 
warm the fresh air before it enters the room ; but 
this is too large a subject for discussion here. 
This foul organic matter from the lungs of ani- 
mals, when it gets out into the open air, is im- 
mensely diluted, and, being acted upon by the oxy- RESPIRATION. 
117 
gen of the atmosphere, is changed into other and 
less harmful substances, which, in their turn, are 
washed down by the rain and become a part of the 
soil. 
153. Contagious Diseases. — The air is not only 
polluted by these products of the respiration of 
healthy animals, but it is made unfit for breathing, 
in a way involving still more danger to life, by 
the matters given off from the lungs and bodies of 
sick persons. There are certain diseases which are 
called contagions or infectious, because they can be 
communicated from one person to another. Such 
diseases are small-pox, measles, scarlet fever, typhus 
fever, diphtheria, and perhaps consumption.* It is 
known that the matters contained in the air expired 
from the lungs, or, in some cases, specks of matter 
cast off from the skins, of persons sick with these 
diseases, will produce similar diseases in persons 
who inhale them. Exactly what it is that repro- 
duces the disease is not known, but there is believed 
to be a microscopic organism, peculiar to each dis- 
ease, which, like a kind of seed, will always produce 
that disease by its own growth and multiplication 
whenever it meets with proper conditions. Whether 
these little organisms ever grow and multiply out- 
side of the body we do not know, but that they do 
so in the blood we have abundant evidence.f 
* Whooping-cough, mumps, and chicken-pox, are propagated in a 
similar manner, but are less dangerous. 
f It is thought by some that malarial fevers (fever-and-ague, etc.) are 
produced by microscopic organisms of this kind, but this is uncertain. 
It is well for those who live in districts where such diseases are preva- 
lent to remember that the poison, whatever it may be, is most active in 
the spring and fall, at night, and near the surface of the ground. In 
such a region, and at such a season, therefore, people should not go 118 
ORGANS OR REPAIR. 
There are other diseases which are believed to 
be produced by similar organisms growing and mul- 
tiplying in the discharges from the stomach and 
bowels. Such organisms are believed to grow out- 
side the body as well as inside, and are supposed to 
be the cause of Asiatic cholera, typhoid fever, and 
yellow fever.'* 
154. Precautions against such Diseases. — It is 
probable that all of these microscopic organisms 
(called bacteria, bacilli, micrococci, etc.) which float 
about in the atmosphere, if they do not find a favor- 
able place in some animal body, where they can 
grow and propagate their kind, finally die. If it 
were not so, the human race would be exterminated 
by them. But men have two ways of dealing with 
them so as to prevent their spreading. One is to 
separate the sick person from well ones, as far as 
possible, and the other is to kill these little organ- 
isms as fast as they leave the body and before they 
can get out of the room. This is accomplished by 
the use of powerful drugs, called disinfectants. 
Nurses and doctors adopt special means of ward- 
ing off infection, or are willing to expose themselves 
out after sundown, should keep, their bedroom-windows closed, and 
should sleep above the first story. 
* The discharges from the bowels and kidneys of healthy persons, 
even, are believed to become dangerous when they decompose, and to 
cause serious diseases. Microscopic organisms multiply in them with 
great rapidity, and are disseminated in the surrounding atmosphere. 
For this reason, it is desirable that such matters should be removed 
from the vicinity of dwellings as quickly as possible. When they are 
discharged into sewers, their decomposition produces various gases— 
some of them very offensive—which are popularly known as sewer-gas, 
but should more properly be called, collectively, sewer-air. The most 
dangerous thing about sewer-air, however, is not the offensive gases, 
but the little organisms that float out with it into the streets or houses. RESPIRA TION. 
119 
to the risk necessary for the proper care of the sick. 
If it becomes the duty of any other person to enter 
a sick-room, he should have in mind the following 
points: that the nose, on account of its narrow pas- 
sages and extensive moist surface of mucous mem- 
brane, acts as a sort of filter, so that many impurities 
of the air are detained there and never reach the 
lungs, whereas, through the mouth, there is a straight 
and almost unimpeded course to those organs; that 
the body is less able to resist injurious influences of 
every kind when it is fatigued or in want of a fresh 
supply of food; and that matters escaping from the 
bodies of the sick and floating in the air are likely 
to settle on articles standing in the room. Hence 
we deduce the following rules: 
Never enter a sick-room when you are hungry or 
tired. 
Always keep your mouth shut, except zvhen talking. 
Never eat or drink anything that has been standing 
in the sick-room. CHAPTER VII. 
ASPHYXIA. 
155. Asphyxia.—When the blood is deprived of 
its constant fresh supply of oxygen, the carbon 
dioxide produced in the tissues accumulates very 
rapidly, and in a short time the blood is brought 
into a condition in which it can not circulate, pro- 
ducing asphyxia or suffocation. The blood through- 
out the whole body then becomes venous. The 
arteries* as well as the veins are filled with black, 
sluggishly-moving blood. This black blood shows 
through the skin, particularly where it is very thin, 
as in the lips; and parts of the body which are usu- 
ally of a healthy red or pink color become blue and 
livid. This blueness of the lips and of the flesh un- 
der the finger-nails is, therefore, a sure indication 
that the person is suffering from a lack of oxygen, 
and the only thing to do to save life, under such cir- 
cumstances, is to supply fresh air. In drowning, 
strangling, poisoning by coal-gas or illuminating 
gas, this is always the great thing to be aimed at, 
and, as long as the heart beats, life exists, and con- 
sciousness can usually be restored. 
* The arteries are those blood-vessels that carry the bright scarlet 
blood, which has received a fresh supply of oxygen, and the veins con- 
vey the dark blood, called venous, which is loaded with carbon di- 
oxide and other waste matters, as hereafter explained. ASPHYXIA. 
121 
156. Drowning. — The length of time during 
which a human being may remain under water and 
still recover, under proper treatment, is not yet act- 
ually determined. Young persons, it is known, live 
longer when submerged than older ones. As a rule, 
however, a person who has been entirely submerged 
for five minutes is dead beyond the possibility of 
resuscitation. And yet, even in such cases, attempts 
should be made, for any case may be an exceptional 
one.* 
157. Resuscitation of the Drowned.—What, then, 
are the indications for the treatment of a person who 
is almost dead from drowning? 
In the first place, he has been for some time de- 
prived of oxygen. It is this which has made him 
unconscious. 
In the second place, he has, probably, in his fran- 
tic efforts to breathe, taken water into his lungs, 
where it stops up the bronchi and air-vesicles, and 
must be cleared out before any air can enter. 
In the third place, he is cold, and warmth, of 
itself, will do much toward bringing about his re- 
covery. 
In the fourth place, his circulation is at a very 
low ebb. The blood is so charged with carbon 
dioxide that it is sluggish, and, possibly, has almost 
ceased to flow. 
We must first, then, turn the person on his face, 
and raise the lower part of the body somewhat, so 
as to let what water there may be in the lungs run 
* Unconsciousness sometimes persists for a long time after a person 
has been removed into fresh air, when no special attempts at resusci- 
tation have been made. It is said that persons have been restored by 
artificial respiration after they have lain unconscious and apparently 
dead for Jive hours. 122 
ORGANS OF REPAIR. 
out by the force of gravity. This action need oc- 
cupy only an instant, for, if there be any water there, 
it will immediately run out. 
The person should then be laid flat upon the back, 
without having the head raised, for we want the 
first fresh blood to run to the brain, and the heart 
is acting so feebly that it will be unable to send it 
there if it has to propel it up-hill. The shoulders 
should be raised a little by a pillow, a folded coat, 
or other padding. All the clothing should be loosened 
about the neck, chest, and waist, so as not to inter- 
fere at all with the movements of respiration. 
The wet, clinging clothing, if convenient, should be 
removed entirely, as it tends to keep up the chilliness 
of the body. In any event, some one should attend 
to the duty of warming the body, by rubbing it with 
warm flannels, by bottles of hot water to the feet, 
etc., etc. 
In addition to these things, and chief of all, arti- 
ficial respiration should be kept up' until the patient 
breathes naturally, or until absolutely all hope is 
lost. 
158. Artificial Respiration.—As the person lies 
upon the back, the arms are to be grasped above 
the elbows and brought upward above the head, so 
as to touch, or nearly so. The large muscles of the 
shoulder are attached to the walls of the chest in 
such a manner that this movement of the arms raises 
the ribs, and expands the cavity of the chest in very 
much the same way that ordinary respiration does. 
The chest being thus expanded, of course air rushes 
in, and inspiration is effected. The arms should 
now be returned to the sides of the body and pressed 
against the ribs, when the chest-walls will recover ASPHYXIA. 
123 
their former position by virtue of their elasticity, 
and expel all the air which had been taken in. This, 
it will be observed, is exactly the process of natural 
expiration. The rapidity of these movements should 
approach as nearly as possible to the rapidity of 
natural respiration—i. e., about sixteen or eighteen 
movements to the minute, and the drawing up of the 
arms above the head should occupy the usual time 
of inspiration. This process should be continued 
for hours, if necessary, and the first sign of recov- 
ery will usually be a slight change in the color of 
the lips and finger-nails to red or pink, indicating 
that the circulation and oxygenation of the blood 
have begun to be more active. 
159. Additional Precautions.—During the whole 
process of resuscitation of a drowned person, care 
should be taken to keep the mouth and throat clear 
of mucus and froth by means of a finger covered 
with a towel. The tongue must also be watched. In 
persons who are almost dead and have lost their 
muscular power, this organ often slips backward 
into the throat, and covers the glottis so that no air 
can pass in or out. It is necessary, in such cases, 
for some person to take hold of the tip of the 
tongue with a towel to prevent its slipping from the 
grasp, and draw it forward so as to leave the pas- 
sage to the lungs clear.* 
As soon as the person begins to breathe he can 
swallow, and a tablespoonful of brandy should be 
given him in a quarter of a tumblerful of water, 
* In all cases of asphyxia, pure air is of the utmost importance. 
The sufferer should therefore be in a well-aired room, and whether in- 
doors or out should never be surrounded by a crowd of people, whose 
respiration will pollute the air before it reaches the one who needs it 
most. 124 
ORGANS OF REPAIR. 
dry clothing should be placed upon him, and he 
should be put in a warm bed until his recovery is 
complete. 
The above directions apply to all cases of suffo- 
cation, where there is no other injury to complicate 
the results of the mere deprivation of air. CHAPTER VIII. 
THE HEART. 
160. General Plan of the Circulation.—The cir- 
culation of the blood is brought about by a compli- 
Fig. 41.—The heart and the large blood-vessels connected with it. The 
greater part of the left ventricle is hidden by the right ventricle. 
cated series of tubes and channels, extending through 
every portion of the body, and all communicating 126 
ORGANS OF REPAIR. 
with each other and with a powerful muscular cen- 
tral organ called the heart. The tubes are called, 
according to their structure, size, and function, ar- 
teries, veins, or capillaries.* 
161. The Heart.—The heart (Fig. 41) is a strong, 
hollow, muscular organ, lying behind the breast- 
bone, with its greater portion to the left of it. It 
is shaped somewhat like a cone, with both ends 
rounded, and the larger end directed upward and 
toward the right. The lower end, or apex, is free 
to move in any direction, not being attached to any- 
thing, while the upper and larger end is held in 
place by the large blood-vessels which are connected 
with it and also with the spinal column. The whole 
organ is covered with serous membrane called the 
pericardium, and lies in a cavity which is also lined 
with serous membrane, so that, like the lungs and 
abdominal organs, its constant movements can go 
on with the slightest amount of friction. 
162. The Double Circulation.—In order to un- 
derstand the action of the heart, it is necessary 
to know, first, that there is a double circulation go- 
ing on in the body at the same time. At every 
contraction of the heart a portion of the blood is 
thrown into the lungs and another portion into the 
remainder of the body; and these two portions 
never mingle with each other. To be more precise, 
and follow a particular mass of blood in its course 
through the body, we may state it thus : The blood 
starts, we will say, from a certain part of the heart; 
it goes directly to the lungs; thence it returns to 
the heart, but to a different part of the organ ; then 
it goes out of the heart in the arteries to what is 
* See Frontispiece. THE HEART. 
127 
called the general circulation—i. e., to all parts of 
the body, excepting the lungs ; thence it is collected 
by the veins, and returns to the heart ; at the next 
contraction it goes to the lungs again, and begins 
the same process; so that in this way all the blood 
passes through the lungs, and all of the blood visits 
all parts of the body; but in doing this it visits and 
passes through the heart twice. In short, it flows— 
I. From the heart to the lungs ; 2. Back to the heart; 3. 
To the rest of the body; 4. Back to the heart. Thus, 
there are two systems of circulation: one, called the 
pulmonary circidation, from the heart to the lungs 
and back again; the other, the general circulation, 
from the heart to the body and back again. 
163. The Two Sides of the Heart.—This double 
and simultaneous circulation can not be brought 
about by a heart containing but one cavity. And, 
accordingly, we find that the heart is divided by a 
muscular partition, running lengthwise of the organ 
from front to rear, into two parts of nearly equal 
size, called the right and left sides of the heart. 
The right side carries on the pulmonary circidation, 
and the left the general circidation. So that the 
course of the blood is as follows : From the right side 
of the heart to the lungs; thence to the left side of the 
heart; thence to all parts of the body ; thence back to 
the right side of the heart. If this order of the circu- 
lation be carefully observed, it will be seen that the 
right side of the heart never contains anything but 
dark or venous blood, and the left side always contains 
bright or arterial blood. 
164. The Auricles and Ventricles.—Each side of 
the heart is divided into two cavities, making four 
in the whole organ. These cavities are called the 128 
ORGANS OF REPAIR. 
auricles and ventricles. The ventricles constitute the 
greater part of the heart, and it is in their walls that 
the greatest muscular power is located. The auri- 
cles are smaller cavities, situated at the upper ex- 
tremity of the organ, and their walls are much 
thinner and weaker than the walls of the ventricles. 
The blood passes from the veins into the auricles, 
from the auricles into the ventricles, and from the 
ventricles it is forced out into the body. The course 
of the blood, then, is from the body in general 
through the veins to the right auricle; from the right 
auricle to the right ventricle ; from the right ventricle to 
the lungs; from the 
lungs to the left auri- 
cle ; from the left au- 
ricle to the left ventri- 
cle ; from the left ven- 
tricle out to the body 
in general, whence it 
is collected by the 
veins and brought 
back to the right au- 
ricle, to begin the 
same course again 
(Fig. 42). 
165. The Valves 
of the Heart. — At 
the mouths of the 
veins, where they 
empty into the au- 
ricles, there are no 
valves, and they are not really needed at this point, 
for the auricles do not contract with much force, 
and as there is always a current in the veins running 
Fig. 42.— Diagram illustrating the course 
of the blood through the heart. THE HEART. 
129 
toward the heart, and as the ventricles lie below the 
auricles, the blood naturally flows into the ventri- 
cles, where it meets with no resistance, rather than 
backward, where it would meet with considerable, 
having to oppose the force of gravity and also 
the current in the veins. In this manner the ven- 
tricles become filled with blood, and, when they 
begin to contract, the case is very different. Here 
there is an enormous pressure to overcome. The 
right ventricle must contract with force sufficient 
to send its contents into the lungs, pushing be- 
fore it the column of blood already in the ves- 
sels. The left ventricle has to contract with a 
force sufficient to send its contents to the remotest 
parts of the body, also pushing along the blood 
which is already in the vessels. On the other hand, 
the resistance backward toward the veins is not 
nearly as great. The current of blood in the veins 
is not strong, and, even supposing that the resistance 
were equal in both directions, it is plain that the cir- 
culation would soon come to an end. The ventricle 
in contracting would force blood backward into the 
auricles and veins, and forward into the arteries, 
and then, when the heart relaxed, the blood would 
flow back again into the ventricles from both direc- 
tions. This danger is averted by the introduction 
of four sets of valves, one between each auricle and 
ventricle, and one at the opening from the ventricle 
into the artery, through which the blood passes dur- 
ing contraction. The valves of the heart are double 
folds of the serous membrane which lines all the 
cavities of the organ, and are stiffened somewhat 
by a few fibers which run between the folds. All 
of these valves have three flaps, excepting the one 130 
ORGANS OF REPAIR. 
which separates the left auricle from the left ventri- 
cle, and this has only two. 
The valves are all so constituted as to allow the 
blood to pass only in one direction. The valves be- 
tween the auricles and ventricles will allow blood 
to pass from the auricles into the ventricles, but not 
from the ventricles back into the auricles; and the 
valves at the mouths of the arteries will allow blood 
to pass from the ventricles into the arteries, but not 
from the arteries back into the ventricles. 
166. The Blood-Vessels connected with the Heart. 
—The large veins, by which all the blood from the 
general circulation is poured into the right auricle, 
are called the vena cava (i. e., the hollow veins); the 
large artery, by which the blood passes from the 
right ventricle to the lungs, is the pulmonary artery ; 
the large veins, by which the blood returns from 
the lungs and enters the left auricle, are the pulmo- 
nary veins ; and the large artery, by which the blood 
goes out from the left ventricle to all parts of the 
body, is called the aorta. 
167. The Circulation of the Blood.—The blood, 
then, coming from all parts of the body in the veins, 
enters through the venae cavae into the right auri- 
cle ; when the auricle is filled, it contracts and sends 
the blood downward into the right ventricle; when 
the ventricle is filled, its walls contract, and the 
blood passes into the pulmonary artery, its return 
into the auricle being prevented by the closure of 
the valves between the auricle and ventricle ; the 
blood then goes through the lungs, and becomes 
changed into arterial blood ; it returns to the heart, 
to the left auricle, and passes from there into the 
left ventricle ; the contraction of the ventricle then THE HEART. 
forces it into the aorta, its return into the auricle 
being prevented by the valves ; from the aorta it 
goes to all parts of the body, to be returned by the 
veins to the right side of the heart. The valves at 
the mouth of the pulmonary artery and the aorta 
prevent the blood which has entered them during 
the heart’s contraction from flowing back into the 
cavity of the ventricle when it becomes relaxed. 
168. Peculiar Valves in the Heart.—There is one 
peculiarity connected with the working of certain 
valves in the heart which is one of the most beauti- 
ful examples of adaptation in the whole body. It 
has been shown that there are no valves at the 
points where the veins enter the auricles, and still, 
when the auricles contract, the blood is not forced 
backward in the veins to any great extent, but passes 
downward into the ventricles. Some of the reasons 
for this have already been mentioned, but there is 
the additional fact that the opening between the 
auricle and ventricle on each side is very large, al- 
most as wide as the auricle itself. There is, there- 
fore, very little resistance, hardly any in fact, to the 
stream of blood passing from either auricle to the 
ventricle. But this large size of the opening might 
give rise to imperfect closure of the valves. The 
valves are made of thin sheets of membrane, stiffened 
a little by fibrous threads, but still very flexible. In 
the pulmonary artery and the aorta, the openings 
from the ventricles are so small that the valves are 
stiff enough to resist the backward pressure of the 
blood and keep the openings closed. The openings 
from the auricles to the ventricles, however, are so 
large that, if there were no special provision to pre- 
vent it, the valves would not only be pressed back- 132 
ORGANS OF REPAIR. 
ward toward the auricle when the ventricle con- 
tracted, so as to meet at their edges and close the 
opening, but, on account of their flexibility, their 
borders would be bent still farther back, so as to 
open into the auricle, and allow a reflux of blood 
into that cavity. 
This difficulty is obviated in the following man- 
ner : There are numerous fine but strong fibrous 
threads or cords attached to the edges of the valves, 
and from that point running downward to the walls 
of the ventricle. These cords are just long enough 
to allow the valves to close perfectly, but not pass 
any farther back toward the auricle. But here an- 
other difficulty arises. If the cords are long enough 
to allow the valves to close at the beginning of the 
contraction of the ventricle when the cavity is at 
its full size, then they will be too long when the 
contraction is toward its end and the cavity is di- 
minished in size, and allow the valves to be pressed 
Fig. 43.—Illustrating the action of the valves in the right side of the heart. THE HEART. 
133 
too far back. In other words, to fulfill their object, 
these cords must be able to become longer or short- 
Fig. 44.—Illustrating the action of the valves in the right side of the heart. 
er according to circumstances. This is effected by 
small muscular projections or pillars, which extend 
from the walls of each ventricle into its interior, and 
to which the cords are attached. When the heart 
contracts, these little pillars contract at the same 
time, and make the cords attached to the valves 
shorter and shorter as the contraction proceeds, just 
in proportion as the cavity of the ventricle grows 
smaller and smaller. In this way the reflux of blood 
through these large valves is prevented (Figs. 43, 
44). 
169. The Contraction of the Heart.—The con- 
traction of the heart does not run successively from 
one auricle to the corresponding ventricle, and then 
from the other auricle to the other ventricle, but the 
contraction of both sides of the heart is simultane- ORGANS OF REPAIR. 
134 
ous. It begins at the auricles and extends down- 
ward until the ventricles are both firm and hard and 
reduced to their smallest possible size. The organ 
then becomes relaxed, and is for an exceedingly 
short time quiet. During this stage of relaxation 
the auricles are being filled with blood from the 
veins, and there is also a current running into the 
ventricles from the auricles. During the stage of 
contraction the blood is being forced into the circu- 
lation through the aorta and the pulmonary artery. 
170. The Sounds of the Heart.—These alternate 
contractions and relaxations of the heart are accom- 
panied by sounds, which are very audible to any one 
who applies his ear to the region of the heart in a 
living person. These sounds are two in number, the 
first being a prolonged, rumbling sound, and the 
second short and sharp. The first sound is made 
during the time when the heart is contracting, and 
the second just at the end of the contraction, or be- 
ginning of relaxation. The first sound is supposed 
to be produced partly by the closing of the large 
valves between the auricles and ventricles, which 
occurs just at the moment when this sound begins, 
and partly by the contraction of the muscular fibers 
of the heart. The second sound is positively known 
to be produced by the closing of the pulmonary and 
aortic valves. It is by the variation in distinctness 
and quality of these sounds, and the addition of 
other sounds to them, that physicians are enabled to 
determine with wonderful accuracy the condition of 
the valves of the heart. 
171. Rapidity of Pulsation in Health.—The con- 
tractions of the heart take place with regularity, and 
average in the adult about seventy per minute. The THE HEART. 
135 
rate is higher in children and women than in men, 
and this fact is probably connected with their greater 
impressionability. The heart-pulsations appear to 
be slower in proportion as the individual is cool and 
deliberate in his judgments. The pulse of Napoleon 
Bonaparte is said to have averaged only forty-four 
to the minute, and is one of the slowest on record. 
Sudden emotions may increase its rapidity and force, 
so that a process, of which we are usually uncon- 
scious, becomes very perceptible and unpleasant, or, 
on the other hand, they may cause it to stop for a 
moment altogether, to skip a beat, as it were, pro- 
ducing the sensation of “fluttering” at the heart. 
Although the action of the heart is thus influenced 
by our feelings, it is beyond our control. Its pulsa- 
tions are ceaseless and regular, until interrupted by 
disease or death. But, notwithstanding this general 
fact, there are some instances on record of persons 
who have been able to affect the action of the heart 
by an effort of the will. The most remarkable one 
of these, perhaps, was a Colonel Townsend, of Dub- 
lin. This person, on several occasions, in the pres- 
ence of medical men, lay down and caused the 
contractions of his heart to become so faint as to 
be imperceptible. During the experiment the cir- 
culation was so far interfered with that he became 
pallid and unconscious. After a half-hour or so, he 
would gradually return to his natural condition. 
As might have been expected, he performed the ex- 
periment once too often. He stopped the action of 
the heart for the last time in the same way as he had 
done before, and it never resumed its work. CHAPTER IX. 
TIIE BLOOD-VESSELS. 
172. The Blood-Vessels.—The heart, although 
a very powerful organ, would not be able to force 
the blood through the whole body, and back to itself 
again, without assistance, and this assistance is fur- 
nished by the structure of the blood-vessels them- 
selves. The blood leaves the heart by the arteries 
and comes back to it through the veins, and these 
two systems of vessels differ very much in their 
structure. 
173. Structure of the Arteries.—The arteries are 
tubes, with strong walls, described by anatomists 
as having three layers. The innermost is a delicate, 
smooth membrane ; the middle one is composed of 
elastic fibers and also fibers of the non-striated or 
involuntary muscular tissue ; the outer one is made 
up of strong connective tissue. Thus the walls of 
the arteries are very elastic, and, if the tube is dis- 
tended, it returns to its former size as soon as the 
internal pressure is removed. 
174. The Pulse.—When the heart contracts, its 
contents are driven with great force into the ar- 
teries, and, as the blood already contained there re- 
sists somewhat the advance of the fresh supply, the 
walls of the arteries are stretched to accommo* THE BLOOD-VESSELS. 
137 
date the mass of blood which is thrown into them. 
When the heart relaxes, and the pressure from that 
direction is removed, the elastic walls of the arteries 
react upon their contents, and, if it were not for the 
valves, would drive the blood, or a portion of it, 
back into the heart. At the slightest backward 
pressure, however, the valves close, and the elas- 
ticity of the arteries thus gives the blood another 
impulse forward toward the surface of the body. 
The impulse given by the heart’s contraction, to- 
gether with that caused by the recovery of their 
natural position by the walls of the arteries, gives 
rise to the pulse, which can be felt at any point in 
the body where an artery runs near enough to the 
surface. The common place of feeling for it is in 
the wrist, merely because that is the most conven- 
ient and accessible; but it may also be felt in the 
ankle, in the neck, in the temple, or in the upper 
arm. 
175. The Capillary Blood-Vessels ; their Struct- 
ure.—The large vessels, by which the blood leaves 
the heart, viz., the pulmonary artery and the aorta, 
divide and subdivide continually, the branches 
growing smaller and smaller as they approach 
their termination, their walls at the same time un- 
dergoing a change in structure. The elastic tissue, 
which is so abundant in the larger arteries, grad- 
ually disappears as the vessels diminish in size, and 
the muscular tissue becomes more prominent, until 
even this finally vanishes, and the smallest blood, 
vessels, called the capillaries, are composed of a 
thin membrane, not divisible into layers. Thus the 
largest arteries are very strong and very elastic, 
while the smaller ones lose in elasticity, but, from 138 
ORGANS OF REPAIR. 
the amount of muscular tissue they contain, are 
very contractile. 
176. Size of the Capillaries.—The capillaries, in 
which the arteries finally end, are only about the 
toVtf °f an inch i11 diameter—just large enough to 
allow the blood-corpuscles to pass through them, 
so to speak, in single file. Their number is beyond 
computation. They are so thickly strewed in the 
body that the point of a fine cambric needle can 
not anywhere be inserted between them. As every 
one knows, it is impossible to find an instrument 
with a point so fine as not to wound a blood-vessel 
if introduced through the skin. These vessels are 
entirely indistinguishable to the naked eye, and, be- 
fore the discovery of the microscope, it was a great 
problem for anatomists to explain how the blood 
got from the arteries into the veins, as they could 
find no direct communication. 
177. The Veins.—After passing through the cap- 
illaries, the blood enters the veins. These vessels 
contain in their walls much less muscular and elas- 
tic tissue than the arteries, and more connective 
tissue. The consequence of this is, that the walls 
of the veins are flaccid and yielding, and, if they are 
cut across, the sides fall together and tend to close 
the opening. If an artery, on the other hand, be 
cut, the tube remains open and in a sense rigid, al- 
though, as will soon be shown, its caliber is some- 
what diminished. The veins, very minute at first, 
gradually unite and become larger and larger, until 
finally all the veins of the general circulation form 
two large vessels, called the vence cava>, which dis- 
charge their contents into the right side of the 
heart—one vena cava receiving all the blood from THE BLOOD-VESSELS. 
139 
the head and upper extremities, and the other that 
from the rest of the body. 
178. Circulation of Blood in the Veins ; Influ- 
ence of Respiration.—The circulation of the blood in 
the veins is brought about in three ways: In the first 
place, the act of respiration has its influence. When 
the chest is expanded by muscular action, every 
fluid which is outside of it tends to rush in and fill 
the enlarged cavity. The chief space is filled by 
the air, as that is more perfectly fluid and meets 
with the least resistance from friction. But the 
blood is also drawn in through the veins, and the 
real extent and power of this suction can be very 
easily seen whenever the entrance of air is im- 
peded. In such cases the veins in the neck can be 
plainly seen to become swollen and full during ex- 
piration, and emptied again during inspiration. 
179. Influence of Muscular Contraction.—In the 
second place, the contraction of the voluntary mus- 
cles aids in the return of the blood to the heart. 
While the arteries, as a rule, run deep in the body, 
out of the reach of injury, the veins are largely near 
the surface, and the whole exterior of the body is 
more or less streaked by the blue lines which indi- 
cate their course. Now, during the contraction of 
a muscle, it not only shortens but becomes broader 
and thicker, and, of course, compresses to a greater 
or less degree everything near it. Thus the veins 
are continually being pressed upon here and there, 
in various parts of the body, during the whole of 
our waking hours, and even to some extent during 
sleep. 
180. The Valves of the Veins. — But merely 
pressing the blood out of a certain portion of a ORGANS OF REPAIR. 
140 
vein might send it in either direction; it would be 
almost as likely to send it away from the heart as 
toward it. This reflux of blood in the veins is pre- 
vented by valves (Fig. 45), which allow the blood to 
pass through them readily toward the heart, but 
not away from it.* These valves are particularly 
Fig. 45.—Diagrams illustrating the action of the valves in the veins. 
numerous in the lower extremities, for here the 
force of gravity acts in opposition to the current of 
blood, and would seriously interfere with the circu- 
lation if there were no special provision with refer- 
ence to it. 
Thus, when blood has been forced out of a por- 
tion of a vein by pressure, it can not go backward 
on account of the valves, but must go forward in 
every case. This fact and the action of the valves 
may be beautifully seen in the arm of any person, 
where the veins are not obscured by too much fat 
beneath the skin. If a place be chosen where a vein 
* It is said that the discovery of the proper working of these valves 
first suggested to William Harvey the true theory of the circulation of 
the blood. THE BLOOD-VESSELS. 
141 
is visible, with no branches for an inch or so, and 
one finger be placed upon it so as to stop the flow 
of blood, the portion of the vein on the farther side 
from the heart will be seen to fill with blood, and 
at some point will probably look swollen. This 
slight swelling marks the situation of a valve. If 
a finger be passed along a vein toward the heart, 
pressing upon it all the time, the vein will be seen 
to fill behind the finger; while if the finger be 
passed in the opposite direction, away from the 
heart, the vein will be empty and collapsed behind 
the finger, and perhaps hardly noticeable. This 
clearly indicates the direction of the current of 
blood. 
181. Influence of the Pressure in the Capillaries. 
-—But the third cause of the venous circulation, and 
the most important of all, is the blood which is con- 
stantly accumulating in the capillaries and exercis- 
ing pressure on the column of blood already in the 
veins. This pressure is unceasing and powerful. 
These three causes, acting together, keep up a 
free and steady flow of blood in the veins toward 
the heart. 
182. Communicating Blood-Vessels.—In both ar- 
teries and veins, there are numerous communicat- 
ing branches, so that, when a blood-vessel is ob- 
structed, the blood passes out into other vessels and 
around the point of stoppage, and, excepting in ex- 
traordinary cases, the nutrition of the part is not in- 
terfered with. 
183. Recapitulation : Rapidity of the Blood-Cur- 
rent in the Vessels.—The arteries, then, carry the 
bright scarlet, highly oxygenated blood from the 
heart out to all parts of the body for its nutrition. 142 
ORGANS OF REPAIR. 
It is sent to the remotest capillaries, partly by the 
contraction of the heart, and partly by the elasticity 
of the arteries; from the arteries it enters the capil- 
laries, where the essential but very obscure processes 
of nutrition are carried on. It has been found that 
the current of blood rushes through the arteries 
with an average velocity of twelve inches per sec- 
ond, but, in consequence of the smallness of the cap- 
illaries and their distance from the heart, as well 
as the magnitude of their combined areas as com- 
pared with that of the aorta, the blood moves 
through them very slowly, not faster, it is thought, 
than one thirtieth of an inch per second. When the 
capillary circulation is looked at through a micro- 
scope, as it may be in the web of a frog’s foot,* it 
is seen that the red corpuscles pass along through 
the minute vessels, sometimes two together, but 
oftener in single file, and without much trouble ; 
but the white corpuscles are more affected by fric- 
tion, and drag along, sticking fast here and there 
until they are started again by the current. This 
slowness of the current of blood in the capillaries 
gives time for the cells of the tissues to take up 
what they want from the vital fluid, and deposit 
their waste to be removed, and so we find that, when 
the blood emerges from the capillaries into the veins, 
it has become of a dark-purple color, and unfit for 
further use in the body until refreshed. So the 
process which takes place in the capillaries is in 
some degree the reverse of that which takes place 
* The foot of a live frog may easily be fastened by strings and pins 
so that it can be placed under the microscope. The thin membrane is 
transparent, and the circulation of the blood, as seen in this way, is per- 
haps the most surprising and instructive sight that can be witnessed. THE BLOOD-VESSELS. 
in the lungs. The blood enters the lungs of a black 
or deep-purple color and comes out bright red. It 
enters the capillaries bright red and comes out dark 
purple. It then passes back to the heart through 
the veins, the steady flow being maintained partly 
by the suction caused in the act of respiration, part- 
ly by muscular contraction and consequent pressure 
on the veins, and mainly by the pressure from the 
capillaries, which constantly forces the blood on- 
ward. 
184. Peculiarity of Pulmonary Artery and Veins. 
—There is one exception to the rule that the arteries 
carry scarlet blood, and one to the rule that the 
veins carry purple blood. The pulmonary artery 
carries venous blooel from the right side of the heart 
to the lungs, and the pulmonary veins bring back 
scarlet or arterial blood from the lungs to the left side 
of the heart. 
185. Rapidity of Venous Circulation.—The ra- 
pidity of the current in the veins is estimated at 
about two thirds of that in the arteries, or about 
eight inches per second. As all the blood which 
goes out through the arteries must return through 
the veins, it might be inferred that the velocity of the 
flow in both systems of vessels would be the same. 
If the capacity of the vessels were the same, it would 
necessarily be so, but there are generally, with rare 
and unimportant exceptions, two veins returning 
the blood sent out by one artery, so that the capac- 
ity of the venous system is as a whole about twice 
that of the arterial, and the velocity would be half 
as great; but, if we take into account the difference 
in the distension and fullness of the two systems, 
the estimate given above, is probably nearly correct. 144 
ORGANS OR REPAIR. 
186. Rapidity of the General Circulation.—An 
interesting- question arises with regard to the ra- 
pidity of the general circulation. Experiments have 
been made which show that this is somewhat great- 
er than would have been expected. A substance, 
which remains unaltered in the blood, and which 
can easily be detected by chemical means, was in- 
troduced into a large vein on the right side of a 
horse’s neck. It was plainly detected in the blood 
drawn from the vein of the left side, in from twenty 
to twenty-five seconds. In this short time, the blood 
in which the substance was introduced must have 
gone down to the right side of the heart, from there 
to the lungs, thence to the left side of the heart, and 
thence through arteries to the head, before it en- 
tered the vein in which it was detected on its way 
back to the heart. 
The time required for all of the blood in the 
body to pass through the heart can not be accurate- 
ly determined, but only estimated. It probably 
varies very much with the vigor of the heart’s ac- 
tion, the amount of exercise taken, the frequency of 
the respiration, etc. In the dead body, however, 
each ventricle is found to contain about two ounces 
of fluid. Now, one ventricle is to be estimated in 
the calculation, because, in order to complete the 
entire round of the body, all the blood must pass 
through the left ventricle. If two ounces enter and 
leave the ventricle at every contraction of the heart, 
and there are seventy pulsations in a minute, one 
hundred and forty ounces, or eight and three quar- 
ter pounds, will pass through the organ in this short 
time. Estimating, then, thirteen pounds of blood as 
the average amount in an adult, two minutes at the THE BLOOD-VESSELS. 
145 
most would suffice for the completion of the circu- 
lation, and this is probably pretty near the truth. 
187. The Supply of Blood in any Part varies.— 
The amount of blood in any portion of the body at 
any particular time depends upon certain relations 
which exist between the blood-vessels and the nerv- 
ous system. The walls of the arteries are plen- 
tifully supplied with involuntary muscular fibers. 
The contraction of these fibers diminishes the cali- 
ber of the artery. They are most abundant in the 
small arteries, and their contraction or relaxation is 
controlled by certain nerves called vaso-rnotor nerves, 
because they control or cause motion in the ves- 
sels to which they are distributed. If the nervous 
stimulus be such as to cause a contraction of the 
arteries supplying any particular part of the body, 
the supply of blood to that part will be diminished, 
and will be diminished in exact proportion to the 
amount of contraction in the blood-vessels. If, on 
the other hand, the nervous control be altogether 
withdrawn, and the arterial walls completely re- 
laxed, the amount of blood in the part affected will 
be increased to a corresponding extent. 
188. The Aorta.—The blood destined for the 
general circulation all leaves the heart through the 
aorta. This is a large vessel, about five eighths of 
an inch in diameter, with thick, strong walls, as it 
has to bear an enormous pressure. It begins at the 
upper end of the left ventricle and on its right side, 
and, after leaving the heart, springs upward toward 
the right, near the breastbone, to the second rib ; 
then arches backward, and passes between the lungs 
to the back; here it curves again, and runs down 
along the spine, through the diaphragm, to the 146 
ORGANS OF REPAIR. 
lower portion of the abdomen—all the way lying 
in front of the vertebrae. When it reaches the pel- 
vis it divides into two branches, one of which goes 
to each lower extremity. 
189. The Femoral Arteries.— These branches 
run the same course in either limb. They emerge 
from the abdomen on the front of the limb, in the 
groin, not far beneath the skin, and pass in as 
straight a line as possible on the inside of the thigh 
to a point behind the knee-joint, at about the middle 
of the hollow space which is 
found there between the ten- 
dons on each side. In its 
course along the thigh the 
vessel is called the femoral 
artery (Fig. 46). At the knee 
it again divides into two 
branches, one of which runs 
down in front of the leg, and 
the other behind to the foot, 
where they further subdivide, 
to supply each of the toes 
with a small artery on each 
side. All through this course, 
however, arteries of different 
sizes are given off as branches 
to supply the different organs 
in the chest and abdomen, as 
well as the muscles and skin, 
the course of the main arter- 
ies only being here indicated. 
190. The Brachial Arter- 
ies.—From the arch of the 
aorta spring upward the vessels which supply the 
Fig. 46.—The right thigh. 
The dotted line represents 
the course of the main ar- 
tery (the femoral). THE BLOOD-VESSELS. 
147 
neck and head and upper extremities. Two large 
vessels go to the arms, one to each. They pass 
upward and outward between the collar-bone and 
the first rib, and dip down 
from the neck, passing to 
the arm through the arm- 
pit. As soon as the artery 
enters the arm it is called 
the brachial, and it con- 
tinues its course down the 
inside of the limb to the 
elbow, where it comes in 
front (Fig. 47). Here it 
divides in two, the radial 
and ulnar, which r.ass 
down, one on each side of 
the arm, to the hand, where 
their subdivision furnishes 
a small artery for each side 
of each finger and the 
thumb. These vessels also, 
throughout their course, 
give off branches to the 
muscles and other parts. 
The radial artery is the one ordinarily felt in order 
to judge of the pulse, and is easily found on the 
radial or thumb side of the arm, about an inch above 
the fold where the hand bends upon the arm. 
191. The Carotid and Vertebral Arteries.—Four 
arteries supply the head and face. These are the 
two carotid arteries in front and the two vertebral 
behind. The two carotids pass up on each side of 
the neck, and, when they approach the skull, divide 
into two main branches, one of which supplies the 
Fig. 47. —The left upper arm. The 
dotted line represents the course 
of the main artery (the brachial). 148 
ORGANS OF REPAIR. 
face, while the other enters the skull and supplies 
the brain. The vcrtebrals supply the brain, and pass 
up to it almost the entire distance inside the bones 
of the spinal column. It is important to know the 
course of the carotid. There is a powerful muscle 
in the neck, which passes upward from the upper 
end of the breastbone and parts in its vicinity to a 
point just behind the ear, where it is attached to the 
skull. Its contraction turns the head, or, with other 
muscles, bends it over to one side or the other. Its 
outline is distinctly perceptible under the skin, par- 
ticularly when it is somewhat contracted, and the 
head thereby a little twisted. The carotid artery 
runs very nearly along the anterior border of this 
muscle, and its beating may be readily felt in this 
situation. 
192. The Large Veins.—Each artery is usually 
accompanied by one or two veins—the largest by 
one, and the smaller ones by two. The veins are 
called, as a rule, by the same name as the correspond- 
ing artery, the most notable exception to this being 
the jugular veins, which are the companions of the 
carotid arteries, and run close by their side. All the 
blood from the lower part of the body is finally col- 
lected in a large vein, called the vena cava inferior, 
which runs up the spine beside the aorta, while that 
from the head, neck, and upper extremities is col- 
lected in the vena cava superior, and both these large 
veins discharge their contents into the right auricle 
of the heart. The veins which take the blood from 
the digestive organs unite to form the portal vein, 
which enters the liver, and the large vein which 
emerges from the liver joins the vena cava inferior, so 
that all the blood from the digestive organs must go THE BLOOD-VESSELS. 
149 
through the liver before it enters the general circu- 
lation. 
The pulmonary artery, soon after it leaves the 
right ventricle, divides into two branches, one of 
which passes under the arch of the aorta, before 
described, to the right lung, and the other goes to 
the left lung. The corresponding pulmo7iary veins 
are two from each lung, and they empty their con- 
tents into the left auricle. CHAPTER X. 
DISORDERS OF CIRCULATION.—HEMORRHAGE. 
193- Obstruction of the Circulation.—If a cord 
be tightly bound about a finger, that part of the 
member which is farthest from the heart will soon 
become livid and begin to swell. This effect is due 
to the difference in structure and position of the ar- 
teries and veins. The arteries are tubes with stiff, 
elastic walls, and do not usually lie very near the 
surface, whereas the veins have thin, inelastic walls, 
and many of them are very superficial. The conse- 
quence is that it is a somewhat difficult matter to 
compress an artery so as to entirely prevent the 
flow of blood through it, while the veins are very 
easily compressed. In binding a cord around the 
finger, then, unless great force be applied, the veins 
are compressed and the current of blood in them 
checked, while that in the arteries is not at all or 
only slightly interfered with, so that blood is being 
continually carried into the finger, and can not flow 
out. The accumulation of blood in the part ac- 
counts for the swelling, and the dark color is that of 
venous blood. If, now, the cord be removed, the 
swelling does not immediately disappear, because 
wherever there is a damming of the current of blood 
so that its flow in the veins is interfered with, after DISORDERS OF CIRCULATION. 
151 
the vessels become distended to a certain point, the 
pressure on their walls is relieved by the loss of a 
portion of their contents. The serum of the blood 
begins to pass through the walls of the veins into 
the tissues outside of them, producing the condition 
called dropsy.* When the circulation of the part is 
restored, all this serum which has left the vessels 
has to be reabsorbed, partly by the blood-vessels 
and partly by the lymphatics, and this occupies an 
appreciable time. 
Now, let us suppose that this obstruction, instead 
of being applied to the veins on the surface of the 
body, is situated in some of the interior organs. It 
is plain that a similar effect will be produced if the 
supply of blood to any part remains the same, while 
the return of it is prevented. Such obstructions are 
most common in the heart and lungs, as a result of 
disease in those parts. 
194. Disease of the Heart.—Let us suppose that 
the valves between the left auricle and left ventricle 
have been inflamed, and have become so altered in 
their shape and size that, when the heart contracts 
to force the blood from the left ventricle into the 
aorta, they do not completely close the opening. It 
is plain that a portion of the blood will be forced 
backward into the auricle. This regurgitation, as 
physicians call it, takes place at every beat of the 
heart, and as the auricle is in this way kept filled 
with blood, and a sort of conflict continually takes 
place between the current coming into it from the 
* When fluid passes in this way from the interior of the blood- 
vessels through their walls into the tissues outside of them, the fibrin 
does not form a part of it. In other words, it is not the plasma that is 
effused, but the serum. 152 
ORGANS OF REPAIR. 
lungs and that coming back to it from the ventricle, 
the current in the pulmonary veins is materially 
interfered with. In short, the blood is dammed 
backward into the lungs. Here, then, is an actual 
obstruction to the circulation, as much as there is 
when we tie a string around the finger. The result 
can be easily ascertained by following backward 
the course of the circulation. The obstruction to 
the exit of blood from the lungs causes the blood 
to accumulate in that organ—in other words, pro- 
duces a congestion there. The blood, not being 
changed frequently enough, does not get enough 
oxygen, and the person is obliged to breathe faster 
in order to supply more. This we call shortness of 
breath. The accumulation of blood in the lungs, 
in a measure, obstructs the current of blood which 
comes to them through the pulmonary artery. The 
blood in the pulmonary artery being hindered in its 
course, the right ventricle is not able to empty it- 
self perfectly, becomes dilated, and its walls become 
thinned. The obstruction at this point prevents the 
right auricle from emptying itself properly, and 
this interferes with the free return-current in the 
large veins which are connected with it. Thus the 
flow of blood is hindered in the veins from all parts 
of the body by the disease of one set of valves. The 
obstruction of the venous flow brings about the 
same results that we have observed in the con- 
stricted finger. The face becomes more or less 
livid, the lips and finger-nails bluish, and the serum 
of the blood passes out into the tissues around the 
veins, causing general dropsy. This is the most com- 
mon form of heart-disease, and it has been somewhat 
minutely described, in order to show how purely DISORDERS OF CIRCULATION. 
153 
mechanical are some of the diseases to which we 
are subject. There are other forms of disease of 
the valves, whose effects may be traced by those 
curious in such things. The aortic valves, for ex- 
ample, may be affected so as to close incompletely, 
and allow a part of the contents of the aorta to be 
forced back into the ventricle by the elasticity of 
the artery every time the heart relaxes. On the 
other hand, these same valves may be made so rigid 
by disease that, although they close tightly enough 
to keep the current of blood from setting back 
through them, they do not open sufficiently wide 
to allow a free flow through them during the heart’s 
contraction. This latter form of disease is one of 
the most common, and gives rise to symptoms very 
much like those of the disease which has been more 
fully described above.. Sometimes, as a result of 
inflammation of a peculiar kind, the edges of the 
valves have small, wart-like masses attached to them. 
These little masses sometimes prevent the valves 
from closing properly, and sometimes not, but they 
always offer more or less obstruction to the circu- 
lation. Occasionally one of these bodies becomes 
detached from the valve by the force of the blood- 
current, and is whirled away through the body. 
As the current of blood in the arteries is continually 
in the same direction, and they grow smaller and 
smaller, such a little body at length reaches a spot 
where the caliber of the artery is too small to let it 
through. It plugs up the artery. This gives rise to 
different consequences, according to circumstances. 
Sometimes the circulation is carried on, in spite of 
the obstruction, by other arteries which pass around 
the point of plugging ; and sometimes the part which ORGANS OF REPAIR. 
154 
receives its supply of blood from the affected ar- 
tery, being thus suddenly deprived of it, dies, fall- 
ing into the condition known as gangrene. 
195. How Heart-Disease is detected. — All of 
these affections of the valves of the heart, interfering 
as they do with the free flow of the blood, give rise 
to sounds of greater or less intensity, the varieties 
of which are familiar to practicing physicians, and 
indicate to them quite accurately the character and 
extent of the disease. 
196. Effect of the Coagulation of the Blood.— 
Whenever the surface of the body is wounded, 
blood-vessels are necessarily severed, and, if there 
were no means of stopping the consequent escape 
of blood, it would not take very long for the whole 
body to be drained. The fibrin of the blood, how- 
ever, by its property of coagulation, serves to arrest 
bleeding. All of the methods used by surgeons to 
stop haemorrhage in any part of the body have for 
their object the coagulation of the blood. 
197. Conditions of Coagulation.—Blood coagu- 
lates much more rapidly on a rough, ragged sur- 
face than on a smooth one, and in a wound that is 
much bruised or lacerated there is often very little 
bleeding, even from large arteries. Instances have 
been known in which the arm has been violently 
torn from the body by machinery, and the brachial 
artery divided, with comparatively little bleeding; 
although, if the arm were cut off, without controlling 
the main artery, the person would die of haemor- 
rhage in a few minutes. In a clean-cut wound the 
haemorrhage is often very severe from small blood- 
vessels, and almost always needs some artificial 
control. HAEMORRHAGE. 
155 
198. Arterial and Venous Haemorrhage.—When 
an artery has been severed, it is not difficult for one 
who understands the circulation to detect it. In 
the first place, the arterial blood is of a bright scar- 
let color, and, in the second place, it comes from the 
vessel in jets or spurts. The blood in the veins is 
dark purple, and, as the veins do not pulsate like 
the arteries, it flows from the wound in a steady, 
uniform stream. The force with which the blood 
issues from a cut artery is surprising. A jet from 
one of the little arteries of a finger will spurt at 
least a foot in a stream no bigger than a knitting- 
needle. A vein never bleeds in spurts. In a wound, 
however, both veins and arteries may be severed 
and the blood mixed, although usually either the 
arterial or venous color predominates. If the blood 
from the wound be soaked up by a sponge or soft 
cloth, an arterial spurt can be seen before the cut 
fills up again with blood. 
199. Natural Arrest of Haemorrhage.—If a wound 
be left to itself, the following are the means pro- 
vided by Nature to arrest bleeding: When an 
artery is cut, its walls always contract somewhat, 
so that its caliber is diminished. The elasticity 
of the artery also draws it backward to some ex- 
tent into the flesh. In the smallest arteries, these 
acts are often sufficient to stop the bleeding en- 
tirely. In every case they resist tfie current, make 
it move more slowly, and so favor coagulation. 
When a vein is cut, the walls, being thin and in- 
elastic, collapse, the opposite sides coming in con- 
tact and tending to obstruct the flow of blood. In 
these ways the current of blood from all cut vessels 
is diminished in force. The blood begins to coagu- 156 
ORGANS OF REPAIR. 
late almost immediately, and this offers still further 
resistance to the out-coming current. If the bleed- 
ing continues, and the blood-vessels are so drained 
that the brain feels the lack of blood, the person 
faints, the nervous force of the heart is diminished, 
and in this way also the force of the flow is less- 
ened. This is Nature’s last resort, and, if the ves- 
sels injured are so large that these means are not 
sufficient to stop the flow, the person will bleed to 
death. 
200. Artificial Arrest of Haemorrhage; Cold.— 
The artificial means which we have at our com- 
mand for arresting haemorrhage merely aim to as- 
sist these attempts of Nature. 
The application of cold to any part of the body 
produces pallor, caused by a diminution in the sup- 
ply of blood to the par1:. This is owing to the fact 
that the stimulus of cold causes contraction of the 
smaller blood-vessels, and so lessens the amount of 
blood in them.* When a cut surface is exposed to 
the air, if the vessels which have been severed are 
small, the coldness of the air is sometimes sufficient 
to stop the bleeding by causing a contraction of the 
vessels. This effect can be increased by bathing 
the wound in cold water. If this be done, however, 
the cut surface should not be wiped or rubbed with 
the sponge or towel, for fear that the already co- 
agulated blood, which begins to form an obstruc- 
tion to the flow, may be washed away. 
201. Styptics.—We also have artificial means of 
bringing on coagulation of the blood. The sub- 
* The diminution in the caliber of arteries in such cases is caused 
by the contraction of the involuntary muscular fibers which surround 
them, as previously explained. HAEMORRHAGE. 
157 
stances used for this purpose are called styptics. 
The persulphate of iron is an exceedingly power- 
ful one. The muriated tincture of iron is another. 
Alum, or tannic acid, or any other astringent, pro- 
duces the same effect. The great objection to all 
of these substances is, that they so alter the tissues 
with which they come in contact that the wound is 
often hindered from healing as rapidly as it other- 
wise would. They are mostly used when it is im- 
possible to apply actual pressure upon the bleeding 
vessels. 
202. Compression.—Compression is the most per- 
fect and unobjectionable method of arresting haemor- 
rhage. This brings no outside injurious matter in 
contact with the wounded surface, and acts merely 
by stopping the flow temporarily until Nature has 
time to stop it permanently. 
If the wound be small, and can be covered by 
the finger, it will generally be enough to put the 
finger or thumb immediately on the cut and press 
toward a bone until the bleeding stops. If the 
wound be too large for this, pressure must be made 
at a point outside of the wound, where the vessels 
which are supposed to be cut are known to run.* 
If the bleeding be venous, of course the current is 
running toward the heart, and the pressure must 
be made on the side farthest from that organ. If 
the haemorrhage be arterial, the pressure must be 
made between the wound and the heart. In the 
* Or some soft, porous material, such as a towel, handkerchief, 
sponges, or cotton cloth or batting, may be crowded into the wound 
and held there by the hand or a bandage. This is often the easiest 
way to apply pressure directly to the mouths of the bleeding vessels. 
Woolen material is too rough and stiff for this purpose. 158 
ORGANS OF REPAIR. 
case of venous hemorrhage, a comparatively slight 
pressure will generally be sufficient, as the walls of 
the veins possess little resisting power, and are 
readily forced into contact. On the arteries, how- 
ever, greater force is necessary, and it is sometimes 
surprisingly difficult to fix the vessel and compress 
it. It is to be remembered that in the limbs the 
course of the arteries is, in the main, nearly straight 
and lengthwise of the limb, so that all that it is ne- 
cessary to do in case of severe arterial haemorrhage 
is to feel along the outer edge of the wound, an 
inch or so from it, pressing the finger down deeply 
until the artery is felt pulsating, and then compress 
it against the nearest bone. 
203. Permanent Arrest of Haemorrhage.—When 
the haemorrhage has thus been temporarily arrested, 
the pressure must in some way be kept up until 
there is no danger of a fresh burst on its removal. 
Nature’s method of permanently arresting bleeding 
is this: It has been before stated that blood will 
coagulate not only outside the vessels, but inside 
them, if its free motion is interfered with. Now, if 
from the contraction of the vessels, or coagulation 
of the blood which has flowed from them, or in con- 
sequence of pressure artificially applied, or for any 
other reason, the current of blood in the artery is 
stopped at the severed end, the fibrin of the blood 
begins very soon to coagulate inside the vessel, and 
this coagulation extends from the cut end backward 
toward the heart to a point where the circulation 
becomes free and unobstructed, that is, to the point 
at which some branch artery is given off from the 
wounded one (Fig. 48). Thus the coagulum (or 
clot) formed will vary, according to circumstances, HEMORRHAGE. 
159 
from an eighth of an inch or less to an inch in 
length. If the compression or other obstruction 
continues long enough to allow of it, 
this coagulum becomes firmly at- 
tached to the inside of the vessel, and 
forms a plug which effectually and 
permanently closes it, and, as the 
wound heals, this plug and the walls 
of the now useless artery become grad- 
ually absorbed until a mere thread 
remains, and even this may disappear 
so as to leave no trace of the vessel 
which formerly existed. But it is to 
be considered that during the forma- 
tion of this plug, and its attachment to 
the walls of the vessel, it has to re- 
ceive the impulse of the blood continually driven 
against it seventy times a minute by the heart; 
and in large vessels this blow is a very strong 
one; so that, if the pressure be removed from 
an artery too soon, even after this coagulum is 
formed, the impulse of the current of blood may 
be sufficient to drive out the plug, and bleeding 
will begin again. This danger is absent in venous 
haemorrhage, and it is a general rule that if such 
haemorrhage is once stopped it will not recur. But 
in arteries this is a peril that must always be 
guarded against, and surgeons accomplish what 
they want by tying the end of the bleeding artery 
with a string. Ligatures, made expressly for this 
purpose, are used, and although they are finally 
discharged from the wound with the secretions, 
showing that they have cut through the walls of 
the vessel around which they were tied, they re- 
Fig. 48.—Clot in 
an artery that 
has been tied. 160 
ORGANS OF REPAIR. 
main long enough to accomplish the purpose.* A 
person’s finger soon becomes exhausted by con- 
tinual exertion in maintaining pressure, but a liga- 
ture keeps the artery closed for several days before 
it comes away, and thus ample time is afforded for 
the permanent closing of the vessel in the way 
above described. The application of a ligature re- 
quires special knowledge and skill, and should only 
be attempted by a surgeon. 
204. Recapitulation.—The means at everybody’s 
hand, then, for arresting haemorrhage are these: 
1. The application of cold by water, ice, or air. 
2. Pressure by the finger, thumb, bandage, or in 
any way that suggests itself. 
(a.) If the wound be small, pressure on the wound 
itself. 
(b.) If the wound be large, and the bleeding 
from the veins, pressure on the side farthest from 
the heart, or by plugging the wound full of some 
soft material. If the blood comes from an artery, 
pressure on the side nearest the heart. 
(c.) Pressure to be kept up until the bleeding 
stops, or until some means can be applied to make 
the pressure permanent. 
3. Styptics or astringents. These are to be used 
chiefly where pressure can not be applied, and after 
the application of cold has proved insufficient. 
205. Wounds of the Extremities.—Wounds of 
the extremities often bleed profusely. Usually, di- 
rect pressure on the spot of the wound will suffice 
* Surgeons are now in the habit of using ligatures made of some 
animal material, such as catgut or chamois-leather, which does not 
irritate the wounded parts, and is gradually absorbed, so that the wound 
can be completely closed when first dressed. HEMORRHAGE. 
161 
to check it. If, however, the wounded vessel is so 
large that it bleeds in spite of this, the main artery 
must be compressed above the wound. It has been 
already shown that the artery is a single trunk 
only in the upper part of each limb—i. e., from the 
shoulder to the elbow in the arm, and from the 
groin to the space behind the knee in the lower ex- 
tremity. Somewhere in this course, then, the ves- 
sel must be compressed against the bone beneath; 
for below the elbow and knee the artery divides, 
and the branches are so sit- 
uated that they can not be 
compressed. The brachial 
and femoral arteries—that 
is, the arteries of the upper 
arm and thigh—are so large 
and strong, and receive 
such a strong impulse from 
the heart, besides being in 
a measure protected by the 
surrounding tissues, that 
they can not be compressed 
by the fingers to any advan- 
tage. The best method yet 
devised is the use of a 
knotted handkerchief or other 
bandage, a rope or cord be- 
ing so small as to cut the 
flesh, and therefore unsuit- 
able (Fig. 49). A handker- 
chief should be tied loosely around the limb, with 
a hard knot over the artery. Immediately under- 
neath the knot should be placed another handker- 
chief, folded so as to form a pad about two inches 
Fig. 49.—Manner of compressing 
an artery with a handkerchief 
and stick. 162 
ORGANS OF REPAIR. 
wide and three long, to keep the knot from bruising 
the flesh when the handkerchief is tightened (Fig. 
50). The handkerchief should be loosely tied in the 
Fig. 50.—Direct compression of a wound by means of what surgeons call 
a graduated compress, made of pads of cloth, folded in different sizes, 
with the largest one on top. 
first place, so as to allow a stick or rod to be in- 
troduced between it and the skin for the purpose 
of twisting it. The stick or lever should be placed 
at some distance from the compressing knot, and it 
is better to put it on the outside of the limb, where 
nothing will interfere with the twisting. The stick 
is now to be twisted round and round, making the 
handkerchief tighter and tighter and the knot press 
down deeper and deeper, until finally the artery will 
be compressed between the knot and the bone, and 
the haemorrhage will cease. This method of com- 
pression is effectual and easy of application, but of 
course is only temporary, for such complete encir- 
cling of a limb and entire stoppage of the circula- 
tion produces gangrene if too long continued. 
206. Fainting.—When, for any reason, the supply 
of blood to the brain is insufficient for its nutrition, 
the person faints. In our ordinary erect position, 
the blood has to be driven upward by the heart for 
a foot or more, in opposition to the force of grav- 
ity. In a fainting person there is not power enough 
to do this, and we must relieve the heart of a cer- HAEMORRHAGE. 
163 
tain amount of its burden. We accomplish this end 
by laying the person flat on his back, without rais- 
ing the head by a pillow or rest of any kind. In 
this position the blood readily reaches the brain, 
and that organ rapidly recovers its functions. 
207. Shortness of Breath.—Shortness of breath 
always indicates that the blood contains too little 
oxygen. When we are short of breath from exer- 
cise, it is due to the fact that our bodies have made 
more waste material than usual, which the blood 
has been unable to get rid of, and also that the oxy- 
gen taken in from the lungs is insufficient for the 
needs of the wasting tissues. In other words, we 
are wearing out. Then we begin to breathe faster, 
and thus try to get rid of more waste and take in 
more fresh material. But, if the exercise which pro- 
duces the excess of waste be continued, the time 
comes when we can not breathe rapidly enough to 
dispose of it, the body becomes limp, and we are 
forced to rest and recover. After we have com- 
pletely ceased our exertions the rapidity of breath- 
ing continues for a time, making the supply much 
greater than the waste, and gradually expelling the 
latter from the body until the balance between the 
two has become even again and the parts are all in 
their natural condition. In diseases of the lungs 
which render parts of these organs useless, such 
as pneumonia, consumption, etc., the same effect is 
produced. When we have only half as much lung 
to breathe with, we have to breathe much faster to 
make up the deficiency. PART IV. 
ORGANS OF CO-ORDINATION\ 
CHAPTER I. 
NERVE-SUBSTANCE. 
208. Difficulty of Investigation.—The nervous sys- 
tem is less thoroughly understood than almost any 
other portion of the body. The difficulties of in- 
vestigation are enormous, and its functions are so 
intimately connected with the phenomena of con- 
scious life that, with the exception of a few facts on 
which all observers are agreed, the truth is buried 
under a mass of conflicting theories, which the 
earnest and tireless efforts of patient workers all 
over the world are not yet able to remove. We 
shall occupy ourselves mainly with what are ac- 
cepted facts. 
209. The Two Divisions of the Nervous Sys- 
tem.—We have seen, in previous chapters, that cer- 
tain operations constantly go on in our bodies, not 
only without our willing them, but without our 
consciousness. Such are the processes of digestion, 
circulation, etc. Our voluntary acts, those which 
are the result of and accompanied by conscious- 
ness, constitute, in fact, the smallest part of what 
goes on within us. Now, the organs which are un- 165 
NER VE-S UBS TANCE. 
Fig. B.—The cerebro-spinal system of nerves. 166 
ORGANS OF CO-ORDINATION. 
der voluntary control are called the organs of animal 
life, while those which are beyond our control are 
known as those of organic life. Corresponding to 
these two divisions of the body are two great di- 
visions of the nervous system—one of which has 
charge of the organs of animal life, and is called the 
ccrcbro-spinal system, while the other regulates the 
processes of organic life, and is called the sympa- 
thetic system. The name of the former indicates the 
fact that it comprises the cer'ebrum, or brain, and the 
spinal cord, with the nerves proceeding from them ; 
and the name of the latter suggests one of the prin- 
cipal characteristics, of that portion of the nervous 
system, viz., that of inducing and regulating a sym- 
pathy between different organs, as will be hereafter 
explained. 
210. Nervous Tissue.—Nervous tissue, wherever 
it is found, is made up of so-called white matter, or 
gray matter, or of both combined. 
211. Nerve-Fibers.—The white matter is found, 
on close examination, to 
be made up of slender 
fibers, running parallel to 
each other (Fig. 51). They 
vary, according to their 
situation, from the 7oVo 
to the of an inch 
in diameter, are nearly 
cylindrical in shape, and 
have for an outer layer a 
thin, delicate membrane, 
which serves to protect 
the nerve-substance and retain it in shape. Just in- 
side the membranous covering is an almost trans- 
Fig. 51.—Nerve-fibers. NER VE-S UBS TANCE. 
167 
parent material, which, after death, appears to co- 
agulate and becomes whitish and slightly granular. 
This is called the my'clin, or, by others, the white 
substance of Schwann, from the man who first de- 
scribed it. In the center of the whole runs a slen- 
der thread of transparent, very finely granular mat- 
ter, called the axis-cylinder. This latter substance, 
in all probability, serves for the actual conduction 
of the nervous influence, whatever it may be, and 
the white substance of Schwann, or myelin, proba- 
bly acts as an insulator. These distinctions be- 
tween the different portions of a nerve-fiber are not 
visible in the living body, but are the result of 
changes which take place after the nerve has been 
separated from its connections, probably from a 
sort of coagulation. 
212. Nerve-Cells. — The gray matter does not 
consist of fibers, but of 
cells (Fig. 52) imbedded 
in a mass of granular mat- 
ter. These cells vary in 
size from to of 
an inch in diameter, and 
each contains a nucleus 
and nucleolus, usually very 
distinctly marked. Each 
cell also has prolonga- 
tions which extend from 
its circumference in vari- 
ous directions, and are supposed in every instance 
to connect either with a nerve-fiber or with some 
other cell. These prolongations vary in number 
from one up to five or six, and, as they are traced 
along their course with the aid of the microscope, 
Fig. 52.—Nerve-cells. 168 
ORGANS OF CO-ORDINATION. 
they are seen to divide and subdivide until they 
become too small to follow. It is supposed that 
every nerve-fiber is connected with such a cell. 
The nerve-fibers, above described, constituting 
the white nerve-matter, are mere conductors of the 
nerve-force. They constitute the means of commu- 
nication between the outside of the body and the 
nerve-centers. The ncrve-cetitcrs, on the other hand, 
are made up of gray matter, and are the originators 
of nerve-force. So we see that the nervous system, 
like the rest of the body, is made up of cells and 
fibers, and that the essential part of the whole is 
the cell, the fiber playing a very subordinate rdle. 
213. Structure of the Nerves.—A nerve which 
is large enough to be seen by the naked eye is com- 
posed of a great number of the fibers above de- 
scribed, lying side by side and bound together by 
a considerable amount of connective tissue. The 
connective tissue is greatest in amount in situations 
where the nerve is most exposed to injury—for ex- 
ample, in the limbs. In the brain, on the other 
hand, and in the spinal cord, where the nerve- 
substance is protected by a strong bony covering, 
the amount of connective tissue is scanty and the 
fibers are very small. 
The white nerve-matter constitutes much the 
larger part of the whole nervous system. It forms 
the great nerve-trunks which go to the limbs and 
to the exterior of the body in every direction, and 
also forms the greater part of the brain and spinal 
cord. 
214. Ganglia.—The gray matter, however, forms 
an important part of the brain and spinal cord, and 
also of various small nerve-centers, called ganglia, NER VE-SUBSTANCE. 
169 
which are scattered throughout the body. In fact, 
every collection of gray matter, which is separated 
from other masses of gray matter by intervening 
white matter, is called a ganglion, and so even the 
different parts of the brain are included under this 
name. 
215. Function of Nerve-Fibers.—The function 
of the nerve-fibers, as has been stated, is to convey 
impressions from one end to the other. Each nerve- 
fiber, even in the largest bundle, is completely iso- 
lated from all others, and runs an uninterrupted 
course from the cell, where it takes its origin, to 
the point of its termination. At its termination, it 
receives an impression, and this impression acts as 
a stimulus, which produces some molecular change 
through the whole length of the nerve, and event- 
ually in the cell from which it comes. How this 
communication is accomplished is not yet known. 
Some change is produced in the nerve, which is 
not to be detected in any way excepting by its effect 
at the farther extremity.* In a similar manner, a 
change originating in a nerve-cell is transmitted 
along the fiber or fibers connected with it, and 
manifests itself at the termination of the fiber in 
some peculiar manner. Some nerve-fibers thus con- 
vey impressions from the outside inward to the 
nerve-centers, while others convey them from the 
nerve-centers outward to the exterior of the body. 
An intelligible illustration of this is to be seen in 
* It has been found by the use of delicate instruments (galvanom- 
eters) that there is a constant electrical current in all nerves in a state 
of rest, supposed to be due to the nutritive changes taking place in the 
nerves. When the nerve is stimulated, however, so that the natural 
nerve-current is conveyed along the nerve, the electrical current is di- 
minished in force. 170 
ORGANS OF CO-ORDINATION. 
the phenomena of ordinary sensation and muscular 
contraction. The prick of a pin stimulates the ex- 
tremity of a nerve-fiber, or perhaps of several. The 
current originated by this stimulus travels along 
the course of the nerve to the nerve-center, and 
produces what we call sensation. Then the nerve- 
center, acted upon by this stimulus, sends out a 
certain amount of nerve-force along another nerve- 
fiber. This impulse follows the course of the nerve 
down to the muscular fiber in which it terminates, 
and there produces contraction of the muscle, and 
removal of the part which has been pricked, out of 
harm’s way. This process, so simple to describe, 
so plain in its gross outline, is probably a very com- 
plex one, and it is not at all understood. When it 
takes place, as it often does, without any conscious- 
ness on the part of the person, it is called reflex ac- 
tion, because the result of the first stimulus, which 
produced the sensation, is reflected, as it were, along 
the second nerve to the muscle. 
216. Rapidity of Nerve-Current.—It seems, at 
first thought, as if the reaction to a nervous stimu- 
lus were instantaneous. If the finger be hurt, it is 
jerked away so quickly that there seems to be no 
interval between the injury and the action. And 
yet it is evident that, if the received theory be true, 
viz., that a current must go from the finger to the 
brain in order to be felt, and from the brain back 
to the muscle in order to produce muscular con- 
traction, there must be a lapse of time. Most people 
would probably say, however, that the nerve-force 
must travel as rapidly as electricity, and hence the 
time required for such a circuit would be inappre- 
ciably short. It has been shown, however, by in- AER VE-SUBSTANCE. 
171 
genious and beautiful experiments, that the nerve- 
force does not travel over one hundred and ten 
feet (thirty-three metres) per second, and hence to 
go from the foot to the brain would require at least 
one twentieth of a second, and the same to return. 
Thus an injury to the foot would not be followed 
by voluntary muscular contraction until at least 
one tenth of a second had elapsed. Electricity, on 
the other hand, travels with almost inconceivable 
rapidity. 
217. Exhaustion of Nerves.—The transmission 
01 an impulse along a nerve-fiber not only requires 
time, but exhausts the nerve. We have previously 
shown that continued muscular contraction exhausts 
the muscular fiber, and that every muscle must have 
rest and nourishment, in order to maintain itself in 
health and vigor. It is the same with the nerves, 
but they recover, when exhausted, much more slow- 
ly than the muscles, and require a longer period of 
rest. 
218. Nerve-Fibers as Conductors of Force.— 
The fact that nerve-fibers are mere conductors of 
nerve-force, and do not originate it, is shown by 
cutting them in two. All sensation and motion 
then cease in the portion of the body supplied by 
the nerve which has been cut. After some time, 
however, such injuries become healed, the cut ex- 
tremities of the nerve unite, and the powers of sen- 
sation and motion return. 
219. Gray Matter originates Force.—It has been 
already stated that the gray matter originates force. 
This is indicated by the fact that all the nerve-fibers 
end in collections of gray matter, and that in the 
natural condition no nerve-fiber conducts an im- ORGANS OF CO-ORDINATION. 
172 
pulse in either direction, inward or outward, un- 
less it be directly connected with gray matter. 
What the force may be which resides in the nerve- 
cells, and what changes accompany their action, 
we do not know, and possibly never shall know. 
It has been often compared to electricity, and was 
once supposed to be identical with it, but it has 
been plainly demonstrated to be different. The 
diminution of the electrical current during the pas- 
sage of the natural nerve-current shows this, and, if 
a nerve be tightly bound, the transmission of the 
nervous impulse is prevented, while the electrical 
current will pass through the constricted nerve 
without appearing to meet with resistance. 
220. Difference between Cerebro-spinal and 
Sympathetic Nerves.—The cerebro-spinal nervous 
system and the sympathetic nervous system bear a 
close relation to the voluntary and involuntary mus- 
cular tissues respectively. The voluntary muscles 
are supplied by nerves from the cerebro-spinal sys- 
tem, and the involuntary largely by the sympathetic, 
and the same differences, that we have observed 
between the two kinds of muscular tissue in their 
manner of contraction, are also found in the two 
systems of nerves. A stimulus applied to any por- 
tion of the cerebro-spinal system produces an im- 
mediate response, while irritation of any portion of 
the sympathetic system only produces an effect after 
the lapse of an appreciable time. 
The only portion of the nervous system over 
which we have any control whatever, and which 
stands in any relation to our consciousness, is the 
cerebro-spinal system (Fig. 53). This system, con- 
stituting by far the greater bulk of our nervous ap- NER VE-SUBSTANCE. 
173 
paratus, comprises the brain and the spinal cord, 
together with all the nerves which take their origin 
Nerves to 
left arm. 
Nerves to 
right arm. 
Nerves to 
front of 
left leg. 
Nerves to 
front of 
right leg. 
Nerves to 
back of 
left leg. 
Nerves to 
back of 
right leg. 
Fig. S3.—Brain and spinal cord, with the thirty-one pairs of spinal nerves. 
in these organs. The brain is a very complex or- 
gan, being composed of several different ganglia, 
each of which has its own peculiar functions. In 
describing the nervous system it will be convenient, 
therefore, to begin with the sympathetic system, as 
being the simplest in its structure and functions. CHAPTER II. 
THE SYMPATHETIC SYSTEM. 
22i. Structure of the Sympathetic System.—The 
sympathetic system consists of a double chain of 
nervous ganglia, running from one extremity of 
the body to the other, not including the limbs (Fig. 
54). The arms and legs are organs of animal life. 
Fig. 54.—The sympathetic system of nerves in the trunk. THE SYMPATHETIC SYSTEM. 
and are supplied with cerebro-spinal nerves. The 
ganglia of the sympathetic vary very much in size, 
some being only visible with the microscope, and 
others as large as a pea, or, rarely, even larger. 
They are composed, as has been said, of gray nerve- 
matter, and are connected with each other and with 
the cerebro-spinal nerves by means of communi- 
cating fibers. Some of these fibers are of the ordi- 
nary white matter, while others are transparent and 
grayish in color, and appear to consist of an axis- 
cylinder alone, without any surrounding myelin. 
The sympathetic ganglia all lie very deep in the 
cavities of the body, in the vicinity of and sur- 
rounding the important organs,* whose functions 
they control, and it is very difficult to get at them 
for purposes of experiment. The consequence 
of this is, that very little has been learned about 
the real action of the sympathetic system, and 
many of its functions can at present only be con- 
jectured. 
222. Sluggish Action of Sympathetic Nerves.— 
The sympathetic nerves have been proved to be 
capable of conveying both sensory and motor im- 
pulses ; but these properties are very slow in mani- 
festing themselves, in marked contrast to the behav- 
ior of the cerebro-spinal nerves. If the extremity 
of a sympathetic nerve be irritated, it is only after 
a considerable time that the nervous center is af- 
* The large sympathetic ganglia, called the solar plexus, or the 
semi-lunar ganglia (from their shape), lying behind the pit of the stom- 
ach, constitute what has been sometimes called the abdominal brain. 
A blow in this region is very dangerous, for, if it is powerful enough to 
paralyze these ganglia by the shock, it is more certain to cause instant 
death than the severest blow on the head. 176 
ORGANS OF CO-ORDINATION. 
fected, and the reflex motion is very slow in its 
appearance. This fact is illustrated in the inflam- 
mations and congestions of internal organs. The 
sympathetic system mainly furnishes the nervous 
supply of the organs of digestion and secretion. If 
any irritation, like the cold air of a draught for in- 
stance, affects the body, the result, such as internal 
congestions, etc., only appear after some time has 
elapsed. An exposure to injurious influences may 
produce a serious disease through the sympathetic 
system, and yet the disease may not declare itself 
for ten or fifteen or even twenty-four hours after 
the exposure. 
223. Contraction of the Pupil.—Various familiar 
phenomena show this sluggish action of the sympa- 
thetic nerves. One of the most obvious is the con- 
traction of the pupil of the eye under exposure to 
light. When a strong light is thrown into the eye 
the pupil grows smaller and shuts out the excess of 
light. On the other hand, when the supply of light 
is diminished, the pupil enlarges so as to admit 
more. Now, these changes in the size of the pupil 
take place very slowly. When we go from a light 
room into a dark one it is several seconds, some- 
times a minute, before we can see anything, simply 
because the pupil does not admit enough light and 
requires time to enlarge sufficiently. When we go 
from a dark room to a very light one we are daz- 
zled ; the pupil is too large and admits too much 
light, and we are obliged to shade our eyes until 
contraction has taken place. These phenomena are 
the result of impressions made on the sympathetic 
system, and serve as an excellent illustration of the 
slowness and precision of its action, as well as of the THE SYMPATHETIC SYSTEM. 
177 
fact that its functions are entirely beyond our con- 
scious control.* 
224. Effect of dividing a Sympathetic Nerve.— 
One of the most remarkable facts relating to the 
sympathetic system was discovered by the cele- 
brated physiologist, Bernard, by the following ex- 
periment: The rabbit’s ear is large and well sup- 
plied with blood-vessels, and is covered with a thin, 
transparent skin, which allows all changes under- 
neath it to be easily seen. If, now, the sympathetic 
nerve running to the ear be divided, the ear be- 
comes red and hot, and the blood-vessels are seen 
to be enlarged and much fuller of blood than they 
usually are. There is no stagnation of the circula- 
tion, and, after the lapse of a sufficient time, three 
or four weeks, the divided ends of the nerve unite 
and the ear returns to its natural condition. If, 
after the nerve has been divided, as above, while 
the ear is in its red and hot condition, the end of 
the nerve nearest the ear be irritated by a galvanic 
current, the blood-vessels contract, the unusual 
amount of blood is expelled from them, and the ear 
resumes its ordinary temperature and color. If the 
cause of irritation be removed, the redness and heat 
return. These facts seemed to indicate that the 
supply of blood in a part was regulated by the sym- 
pathetic system of nerves, a supposition which was 
confirmed by further experiments. 
* The iris, i. e., the muscular curtain surrounding the pupil, is sup- 
plied with nerves from the cerebro-spinal system as well as from the 
sympathetic. The relative functions of the two sets of fibers are not 
well understood, but the sluggish and involuntary character of the 
changes in the size of the pupil shows that the influence of the sympa- 
thetic nerves predominates. ORGANS OF CO-ORDINATION. 
178 
225. Influence of the Sympathetic Nerves on Se- 
cretion.—He found that, if the sympathetic nerve 
supplying one of the salivary glands be divided, 
an increased supply of blood takes place and in- 
creased secretion by the gland follows. The sub- 
maxillary gland being treated thus, an increased 
flow of saliva takes place. A similar effect is pro- 
duced by galvanic irritation of the nerve of taste. 
Any savor}' substance in the mouth, then, irritat- 
ing the nerve of taste, gives rise to a reflex action 
through the nerves supplying the salivary glands, 
and produces a flow of saliva. This is what we 
call “ feeling the mouth water.” The same ef- 
fect may even be produced by purely emotional 
causes, as the mere sight of an appetizing article 
of food. 
226. Effect of Emotion on the Sympathetic 
Nerves.—Blushing is another phenomenon depend- 
ing on the control of the sympathetic nerves over 
the blood-vessels. The emotion of shame produces 
a temporary paralysis of the sympathetic nerves, 
and gives rise to the same effects as a division of the 
nerve. Blood rushes to the superficial blood-vessels 
and they become redder and hotter than they ordi- 
narily are. The blush is more evident in the cheeks 
than elsewhere, because the skin is thinner there, 
and the blood-vessels more numerous ; but the 
blush extends, in reality, much more widely than is 
commonly supposed, and covers a large portion of 
the surface of the body. The peculiar character- 
istics of the sympathetic system are to be plainly 
discerned in the blush. It is not instantaneous, but 
comes on slowly after an indignity, gradually rises 
to its greatest height, and then gradually disap- THE SYMPATHETIC SYSTEM. 
179 
pears. It is also beyond the control of the will. 
If a person really feels the emotion, he can not re- 
strain the blush. The only means of preventing’ it 
lies in such a constant schooling of the mind that 
feelings of shame, modesty, insulted dignity, etc., 
shall not be felt. When a person has arrived at 
this point of self-control he will not blush. But who 
would wish to purchase exemption at such a price ? 
Many persons are ashamed of blushing, but who 
would be ashamed of being ashamed ? The two 
can not be separated, and one who has lost the sense 
of shame entirely has lost much of what commends 
us to the sympathy and respect of our fellows. 
227. The Vaso-motor Nerves. — The nerves 
which thus control the supply of blood to the 
blood-vessels are called the vaso-motor nerves. They 
have been already referred to in another part of 
this book. They have received the name of vaso- 
motor because they control the motion of the walls 
of the vessels (vasa) producing contraction or relax- 
ation. Although they are chiefly of the sympa- 
thetic system, they receive fibers from the cerebro- 
spinal system. The two systems are not entirely 
distinct from each other, but there are certain func- 
tions in which they are so widely different that we 
can say with certainty this action belongs to the 
cerebro-spinal system, or that one to the sympa- 
thetic ; while between these extremes are all sorts 
of gradations, so that in many cases we are unable 
to distinguish the characteristics of either system, 
and must say of them that we do not know how 
they are produced or that both systems probably 
unite their functions. 
228. Influence of the Sympathetic System on Di- ORGANS OF CO-ORDINATION. 
180 
gestion.—The process of digestion is presided over 
and regulated mainly by the sympathetic nervous 
system. The introduction of food into the stomach 
stimulates the nervous ganglia in the abdomen, and 
through their influence is followed by all the phe- 
nomena of secretion, muscular movements, and ab- 
sorption, which have been shown to accompany 
and form a part of the process of digestion. All of 
these phenomena are beyond our control, but, as 
has been shown in the case of the blush, the nervous 
supply of the sympathetic is favorably or unfavor- 
ably affected by strong emotions. And it is through 
these ganglia and their connections that anger, fear, 
or other depressing emotions, produce such an in- 
jurious effect on the digestive organs during and 
after a meal. 
229. Effect of Cold on the Sympathetic System.— 
It is through the reflex action of these nerves, also, 
that haemorrhage can often be checked by the ap- 
plication of cold, and that inflammation of internal 
organs may result from the same cause. The mu- 
cous membranes, for the same reason, seem to be 
more exposed to such inflammations than any other 
portion of the organism. Hence, exposure to a cold 
draught is very apt to bring on such a disorder. In 
one person it may affect one mucous membrane, in 
another another, according to the relative condition 
of the membranes at the moment. After such an 
exposure, one person may have a severe cold in the 
head, another a bronchitis, another a sore throat, 
another a diarrhoea or inflammation of the mucous 
membrane of the intestines.* All of these results 
* Many persons, instead of catching cold in the nose or throat after 
exposure, have their bowels affected, and the resulting catarrh causes a THE SYMPATHETIC SYSTEM. 
181 
are beyond our control, and the only way to pre- 
vent them is to keep out of danger. When a person 
is in health, food introduced into the stomach will 
inevitably be digested, whether he wills it or not, 
and, if he undergoes certain exposures, he will take 
cold, in like manner, whether he wills it or not.* 
230. Exhaustion of the Sympathetic System.— 
As the sympathetic system is so intimately con- 
nected with the processes of nutrition, and indeed 
with all the functions of those organs which main- 
tain us in life, without our consciousness, it is evi- 
dent that it should be well taken care of and nothing 
done to cripple it. We have, then, to bear in mind 
that nerves require rest as well as any other part of 
the body, that they easily become exhausted, and 
that they require a longer period for recuperation 
than the muscles do. The surest sign, perhaps, of 
exhaustion of the sympathetic system will be found 
diarrhoea. When a person is specially liable to this affection, he should 
wear a thick flannel bandage around the abdomen, which will furnish 
almost entire relief from such attacks. 
* A cold is generally the result of the sudden chilling of some part 
or the whole of the surface of the body. The first effect of such a chill 
is to contract the blood-vessels on the surface and overfill those that lie 
deeper, and thus to cause congestions of the internal organs. Such an ef- 
fect seems to be especially apt to follow a cold draught striking the back 
of the head or neck or the ankles. Now, active muscular exercise tends 
to drive the blood to the surface, and is therefore a natural preventive 
of colds. It tends to keep the blood at the surface, where a conges- 
tion will be relieved by perspiration, and prevents its accumulation in 
the deeper organs, where it is more likely to cause trouble. If expos- 
ure to cold, therefore, can not be avoided, we must keep up a brisk 
circulation by physical exercise. Wet clothing should be changed for 
dry as soon as possible, for so long as it remains in contact with the 
body it absorbs a great amount of heat from it and keeps up a constant 
chilling of the surface. When a person is not engaged in physical ex- 
ertion, he should avoid draughts. 182 
ORGANS OF CO-ORDINATION. 
in failure of nutrition. If a person grows thin and 
pale and languid, notwithstanding a good supply 
of food, or if his food be not appropriated by the 
body—in short, if his nutrition become impaired, 
and no organic disease be discoverable—it is prob- 
ably the result of nervous exhaustion, and means 
should be taken to relieve the overtasked organs. 
Rest will accomplish wonders in many cases of ill- 
ness, especially where there is no disease of any 
particular organ to be detected. CHAPTER III. 
THE SPINAL CORD. 
231. Structure of the Spinal Cord.—The spinal 
cord is that portion of the nervous system which 
lies within the spinal canal. It extends from the 
junction of the spinal column with the skull, down 
to the loins, and is about a foot and a half long and 
a little less than half an inch in diameter. It weighs 
about an ounce and a half. It does not occupy the 
whole spinal canal, but the space around it is filled 
with membrane, blood-vessels, and nerves. At its 
upper extremity it passes into the brain, and at its 
lower, just below the last rib, it divides into a bundle 
of small nerves, presenting very much the appear- 
ance of a tassel at the end of a thick cord.* 
The spinal cord consists partly of white and 
partly of gray matter. The gray portion occupies 
the central portion of the cord, and is arranged 
somewhat in the form of the letter H, with the two 
upright marks curving outward at both ends (Fig. 
55). The remainder of the cord, in which this gray 
substance is imbedded, is composed of white matter. 
The spinal cord, throughout its whole length, is 
divided by fissures, one of which extends from be- 
* This part of the spinal cord is called the caud’a equi'na—i. e., the 
horse's tail, which it somewhat resembles. ORGANS OF CO-ORDINATION. 
184 
fore backward, and the other from behind forward, 
the two nearly meeting-. They are, however, sepa- 
rated, and the halves of the cord kept in communi- 
cation by a bridge of gray matter, which passes over 
from one to the other, forming the cross-line of the 
letter H. 
232. The Spinal Nerves.—The spinal cord sends 
out nerves through its whole course. With the ex- 
ception of the head and face, all the muscles and the 
skin of the body receive their nervous supply from 
this source. These nerves, thirty-one pairs in all, 
issue from the spinal column between the vertebrae 
through small openings. 
233. Properties of the Spinal Nerves.—All parts 
of the body, which are supplied with spinal nerves, 
are endowed with two remarkable properties, sen- 
sation and motion. As long as the nervous supply 
remains in a natural and healthy condition, any por- 
tion of the body feels, and any portion can be moved 
from one place to another. These movements are 
sometimes voluntary and sometimes we are entirely 
unconscious of them, and it is only within a few 
years that physiology has been able to offer any ex- 
planation whatever of these facts. 
234. Sensation and Motion.—When we consider 
attentively the property of sensation, we find that 
there are two great divisions of it, easily distin- 
guishable and easily demonstrated, viz., sensibility 
to pain and orduiary sensation. When a person is 
brought under the influence of an anaesthetic, the 
sensibility to pain disappears before ordinary sen- 
sation is lost, and even while the individual is still 
conscious. In slight surgical operations this fact 
is often strikingly manifest. A tooth may be pulled, THE SPINAL CORD. 
185 
and the patient be conscious of every step of the 
proceeding, without feeling the slightest pain. Nar- 
cotics, too, may relieve the pain of a neuralgia, 
while the person who has taken them remains per- 
fectly in possession of his senses. Physiologists 
have made other discriminations of sensation, which 
it is not necessary to mention here. 
The phenomena of motion are familiar, and re- 
quire no separate consideration. 
235. Effect of dividing a Nerve.—If one of the 
spinal nerves be cut in two, sensation and motion 
are abolished in the portion of the body supplied 
by that nerve. This shows that sensation and mo- 
tion are both conveyed in the same nerve. But 
here a difficulty arises. Sensation implies the pas- 
sage of a nerve-current from without inward, to- 
ward a nerve-center; whereas motion implies the 
passage of a current from within outward, from the 
nerve-center to the muscle. Can both these cur- 
rents be transmitted at the same time, or can the 
axis-cylinder of the nerve-fiber be used for the pas- 
sage of the nerve-current in either direction accord- 
ing to circumstances? This is the problem which 
waited until this century to be solved. The sim- 
plest explanation has been found to be the correct 
one. As every nerve is made up of many fibers, it 
would be natural to suppose that some of these 
fibers might serve as conductors of sensation, and 
others of motion. This was made all the more 
probable by the fact that, in many forms of dis- 
ease, it was seen that the power of sensation might 
be abolished, while that of motion remained ; or, on 
the other hand, the power of motion might be par- 
alyzed, while that of sensation remained unimpaired. 186 
ORGANS OF CO-ORDINATION. 
And, in fact, the above explanation of these phe- 
nomena was found to be correct. The first who 
demonstrated this appears to have been Sir Charles 
Bell,* although Magendie f has strong counter- 
claims to the honor. The experiments by which 
the truth was established were decisive, and have 
been often repeated by other physiologists. They 
are the following; 
236. The Roots of the Spinal Nerves.—The spi- 
nal nerves do not take their origin from the spinal 
cord as single trunks, but each one arises by two 
roots. One of these roots is formed of fibers com- 
ing from the anterior portion of the cord, and is 
called the anterior root; the other is formed by 
fibers from the posterior portion of the cord, and 
is called the posterior root; the latter, at a short dis- 
tance from its source, passes through a small gan- 
glion of gray matter. These two roots, anterior 
and posterior, approach each other and unite in a 
single cord just before leaving the spinal canal. 
This cord, therefore, contains fibers from both por- 
tions of the spinal cord, and, after running a short 
distance, it again divides into two nervous trunks, 
one of which supplies the front of the body and the 
other the back. 
The experiments referred to consisted in divid- 
ing, not the nerves, but the anterior and posterior 
roots of the nerves, inside the spinal canal, in a liv- 
* Sir Charles Bell, a distinguished Scotch anatomist, physiologist, 
and surgeon (1774-1842), Professor of Surgery in the University of 
Edinburgh. 
f Francois Magendie, a celebrated French physiologist (1783-1855), 
Professor of Anatomy in the College of France, especially well known 
for his experiments on living animals. THE SPINAL CORD. 
187 
ing animal, and watching the result. Severe and 
painful as these experiments were, and however ob- 
jectionable from the animal-lover’s point of view, 
they have probably done more to explain the mys- 
teries of the nervous system, and to give a fresh im- 
pulse to investigation on the most interesting and 
important subject with which man can occupy him- 
self, than any similar experiments in the world’s 
history, if we except those which demonstrated the 
circulation of the blood. 
237. Division of the Anterior Root.—When the 
anterior root of a spinal nerve is divided (Fig. 55), 
the portion of the body supplied by the nerve of 
Fig. 55.—Cross section of spinal cord and roots of spinal nerves, with ante- 
rior root cut. 
which this particular root forms a part, loses its 
power of motion, but preserves its sensibility unim- 
paired. If the portion of the body supplied by this 
nerve be pinched or pricked, the animal gives evi- 
dent signs of pain, and endeavors to get out of the 
way of the irritation, but is utterly unable to move 
the muscles of the part. If, now, the ends of the cut 
nerve be irritated, the following results are obtained: 
On irritation of the end nearest the part supplied 
by the nerve, the muscles of that part become strong- 
ly contracted, or convulsed, while the animal gives 
no indication of feeling anything whatever. If the 
end nearest the spinal cord be irritated, no effect 188 
ORGANS OF CO-ORDINATION. 
whatever is produced. There are no convulsive 
movements of the muscles, and no indication of sen- 
sation. This seems to show that, in the fibers of 
the anterior root, the nervous impulse is transmit- 
ted from within outward, and gives rise to the phe- 
nomena of motion, while they have nothing to do 
with sensation. 
238. Division of the Posterior Root.—If, now, 
instead of dividing the anterior root, we divide the 
posterior (Fig. 56), we find that the part supplied by 
the nerve has lost sensation, but retains the power 
FlG. 56.—Cross section of spinal cord and roots of spinal nerves, with pos- 
terior root cut. 
of motion. If it be pinched, pricked, or injured in 
any way, no effect is produced, and the animal ap- 
pears to take no notice of it whatever. This shows 
that sensation in the part is abolished. If, now, the 
cut ends of the root be irritated, we find the follow- 
ing results: On irritation of the end nearest the part 
no effect whatever is produced. If, on the other 
hand, the end nearest the cord be irritated, the ani- 
mal utters cries of pain, and moves the muscles sup- 
plied by the nerve which has been operated on, in 
endeavors to escape. This shows'that the power 
of motion has not been interfered with by the oper- 
ation, and it also shows that, in the posterior roots of 
the spinal nerves, the nervous impulse is transmitted 
from without inward, and has to do with sensation. THE SPINAL CCRD. 
189 
239- Two Kinds of Fibers in Each Nerve.—The 
anterior roots, then, are composed of motor fibers, 
and the posterior roots of sensory fibers. The two 
unite, as has been shown, to form a single cord, 
which afterward divides again to supply the front- 
and back of the body. Every spinal nerve in this 
way is made up of both sensory and motor fibers, 
or fibers which convey sensation and fibers which 
convey motion ; and thus, from the constitution of 
the nerve, it is easy to see how the powers of sen- 
sation or motion can be abolished separately, one 
remaining intact while the other disappears. 
240. Relation of the Spinal Cord to the Brain.— 
These properties of sensation and motion have been 
considered only in their relations to consciousness. 
The sensations have been spoken of as felt by the 
animal, and the movements as voluntary. In order 
for this to be so, there must be some connection be- 
tween the nerves and the brain, for consciousness 
has its seat in the latter, as we shall hereafter see. 
And in fact it has been proved that the nerve-fibers, 
after entering the spinal cord, pass upward in its 
interior toward the brain. It is probable that the 
white matter of the cord is largely composed of 
fibers which connect the brain in this way with the 
exterior of the body. 
As the nerve-fibers approach the brain, however, 
at the very summit or upper extremity of the spi- 
nal cord, they cross over from one side of the cord 
to the other, the fibers from the right side passing 
over to the left, and those from the left going over 
to the right. The crossing of the motor fibers only 
takes place at this point, while the sensitive fibers 
cross to the opposite side of the cord soon after 190 
ORGANS OF CO-ORDINATION. 
joining it. The consequence of these facts is, that 
the right side of the body comes into direct com- 
munication with the left side of the brain, and the 
left side with the right brain. An injury to the 
brain, therefore, on either side, produces paralysis 
of the opposite side of the body. An apoplexy* 
affecting the right side of the brain brings on paraly- 
sis of the left side of the body; and conversely, if we 
see a person whose left side is paralyzed, we look 
for the injury which has caused it on the right side 
of the head. 
241. Sensations referred to Extremity of Nerve. 
—It has already been said that the nerve-fibers act 
merely as conductors of an impulse, and do not 
themselves originate nervous force. In consequence 
of this, an injury to any portion of a nerve always 
produces the same effect as if it were at its extrem- 
ity. The pain which results from any impression 
on a nerve-fiber is always referred by the nerve- 
center which receives it to the termination of that 
particular nerve. And this fact clearly explains 
many things that once were not understood. The 
ulnar nerve furnishes a good illustration of this. At 
the inside of the back of the elbow are two bony 
projections, with a hollow canal between them. At 
the bottom of this canal, not far below the skin, runs 
a large nerve called the ulnar nerve, because it sup- 
plies the ulnar side of the fore-arm and hand. If 
this nerve be pressed or injured in any way, a tin- 
gling sensation is felt in the little finger and the ad- 
* Apoplexy, from the Greek, meaning a sudden stroke. It is caused 
by the giving way of some blood-vessel in the brain, and the blood 
escaping into, compressing, and tearing apart the delicate nerve-tissue, 
causes paralysis and often entire unconsciousness, or death. THE SPINAL CORD. 
191 
joining side of the ring-finger, the parts supplied by 
this nerve.* Striking examples of the same phe- 
nomenon are often seen in persons who have lost 
limbs by amputation. If the end of the nerve which 
remains in the stump be irritated in any way, as by 
the contraction of the scar, the person feels the irri- 
tation precisely as if it were in the lost limb. If any 
person’s arm were cut off, for instance, just below 
the elbow, and the stump of the ulnar nerve were 
irritated, he would feel the tingling sensation in the 
little and ring fingers of his hand just as much as if 
the hand were still attached to the arm. The sen- 
sation is precisely the same, and can only be cor- 
rected by the sense of sight or by the individual’s 
own memory or reason. It is this fact which has 
given rise to the numerous accounts of persons who 
have felt people maltreating their amputated limbs, 
when they perhaps were already decayed, or were 
hundreds of miles away. 
242. Reflex Action of the Spinal Cord.—All the 
phenomena which have been described might occur 
just as well if the spinal cord were merely a large 
bundle of white fibers running down from the brain, 
and sending out branches to different parts of the 
body. It has, however, a considerable amount of 
gray nerve-matter in its interior, and, as we have 
seen that this form of nerve-matter originates force, 
we are prepared to infer that the spinal cord can 
* The ulnar nerve supplies the little finger, the adjoining side of 
the ring-finger, and that side of the hand as fhr as the wrist. Pressure 
upon it, therefore, interferes with the nervous supply of those parts, 
and they tingle and become numb. The queerness of the sensation 
produced has caused this nerve to be commonly known as the crazy- 
bone, or the funny-bone, although it is not a bone at all. ORGANS OF CO-ORDINATION. 
192 
originate movements and receive sensations without 
any connection with or dependence on the brain. 
And this is found actually to be the case. If the 
head of a frog be cut entirely off, leaving the body 
otherwise uninjured, sensation and motion are still 
manifested in the trunk and limbs. If the toe be 
pinched, the leg will be drawn up out of the way. 
This is the same effect that is produced when the 
animal is entire, with this exception: there is no 
attempt to escape from further injury. In other 
words, there is no brain-action, no reasoning. The 
irritation sends a nerve-current along the sensory 
nerve to the spinal cord. There it produces cer- 
tain changes in the cells of the gray matter, and 
from them another current is sent outward along 
the motor nerve to the muscles, and movement re- 
sults. If the nerve be severed, no such effect can 
be produced. If the spinal cord be destroyed, the 
nerves remaining intact, no such effect will occur. 
These facts show that the cord itself has the prop- 
erty of receiving sensations and sending out motor 
impulses. This action of the spinal cord, by which 
it produces a movement in response to and in con- 
sequence of a sensation, is called reflex action. 
. 243. Diseases of the Spinal Cord.—Experiments 
like the above, of course, can not be performed on 
human beings, but the course of nature often per- 
forms them for us. Diseases are not uncommon in 
which the spinal cord is completely cut across in 
some portion of its length, so that there is no nerv- 
ous communication between the brain and that part 
of the body below the seat of disease or injury. 
In such cases we have paralysis of the kind called 
by physicians paraplegia—i. e., the lower portion of THE SPINAL CORD. 
193 
the body is no longer under control of the brain, 
and no longer capable of voluntary movements. It 
is also entirely beyond the domain of consciousness; 
injuries to the paralyzed part cause no sensation in 
the brain. The separation of such a part of the 
body from all relation to consciousness, whether of 
sensation or of motion, is as complete as if it formed 
part of another body. Notwithstanding this fact, 
we often find the spinal cord below the seat of inju- 
ry to be in the same condition as that of the decapi- 
tated frog. If the disease or injury has been con- 
fined to a particular part of the cord, and the portion 
below, with its nerves, be still in a healthy condition, 
excepting that it is separated from the brain, a stim- 
ulus applied to any of the nerves will produce a 
response which is immediate and decided. A person 
in this condition looks on and sees his feet pinched, 
or pricked, or burned, and sees the irritation followed 
by violent convulsive kicks and thrusts of the limbs, 
without the slightest knowledge of what is going on, 
excepting what he receives through the sense of sight. 
244. Automatic Actions.—Certain actions, which 
are at first voluntary, and only accomplished by great 
effort, become, after a time, so natural and easy, that 
they seem to be carried on unconsciously, through 
the action of the spinal cord. Thus, in the act of 
walking, a harmonious action of several muscles is 
required to keep the balance, an action which is 
at first learned only after prolonged and incessant 
effort. In after-life it becomes so easy as to be 
carried out without consciousness, as has been often 
shown in the case of soldiers, who have continued 
to walk in the ranks and keep up with their com- 
rades on the march while fast asleep. CHAPTER IV. 
THE BRAIN. 
245- The Brain.— 1 he brain and the cerebrum are 
often spoken of as if they were convertible terms. 
But this is not correct. The brain includes all that 
part of the nervous system which lies within the cav- 
ity of the skull. This great mass of nervous matter 
is made up of several distinct ganglia, which, to be 
sure, are connected with 
one another and interde- 
pendent, and yet each of 
them has its own particular 
function which the others 
have not (Fig. 57). The cere- 
brum is merely one of these 
ganglia, and, although the 
highest in the scale as re- 
gards the character of its 
functions, it being the gan- 
glion which principally 
gives man his pre-eminence 
over the lower animals, it is 
one of the least important 
as regards the mere preservation of life. In many 
of the lower animals it can be entirely removed, and 
the animal will live for months afterward. In the 
Fig. 57.—Diagram showing the 
position of the nervous cen- 
ters in the head. THE BRAIN. 
195 
human being it is so plentifully supplied with blood- 
vessels that, if its removal should be attempted, the 
person would die of hasmorrhage. This has been 
the invariable result of experiments on the higher 
kinds of animals, as the dog or horse. But there is 
no doubt that, if the cerebrum could be removed 
without interfering with the circulation of the blood, 
even a human being would continue to live with- 
out it. 
246. Structure of the Cerebrum.—The cerebrum 
(Fig. 58) is the largest part of the brain, forming as 
Fig. 58.—Under surface of the brain, showing the great complexity of its 
structure. At the lower part of the cut is the cerebellum. 196 
ORGANS OF CO-ORDINATION. 
it does about nine tenths of the whole mass within 
the skull. It consists of two halves, called hemi- 
spheres, the dividing- fissure running from the front 
of the head to the back; but the halves are not en- 
tirely separated. On their under side, a bridge or 
mass of white fibers runs from one to the other, and 
serves as a means of nervous communication be- 
tween them. The cere- 
brum is composed of both 
white and gray matter, the 
latter being spread over 
the surface, and the former 
filling up the interior, and 
forming the greater por- 
tion of the mass (Fig. 59). 
The arrangement of 
the nerve-matter of the 
cerebrum is very peculiar. 
It is formed into folds and 
wrinkles, somewhat like 
the meat of an English 
walnut. These folds are 
called the convolutions of 
the brain, and, as the gray 
matter follows closely the 
dipping of the surface be- 
tween the convolutions, it 
is evident that the amount 
of gray matter is much 
greater than it would be 
if the surface of the brain 
were smooth. 
It has been found by experiment that the nerve- 
natter composing- the cerebrum is insensible to 
Fig. 59.—Section of the brain, show- 
ing the arrangement of the gray 
and white substance. THE BRAIN. 
19 7 
ordinary irritation. Either the gray or the white 
matter may be cut, pricked, burned with fire or 
caustic acids, without producing any sensation. 
What, then, is the function of the cerebrum ? 
247. Function of the Cerebrum.—It is now ac- 
knowledged by all who have paid any attention to 
the subject, that the cerebrum is the organ of thought. 
It is in this part of the brain that all ideas have their 
origin, and that all processes of reasoning take place. 
The evidence of this is indirect, but very conclusive, 
and may be briefly stated as follows: 
248. Intelligence increases with Increase in Size 
of the Cerebrum.—The cerebrum increases in size 
in animals as we pass from the lower forms to the 
higher. The superiority of one animal over another 
in the scale of life depends mainly upon what we 
call intelligence. Now, we find that the intelligence 
of animals appears to increase in the same ratio that 
the size of the cerebrum increases in proportion to 
the rest of the body. In the fish, the cerebrum is 
very small, and his intelligence is very low. In the 
reptiles, the cerebrum is somewhat larger, and their 
intelligence as a class greater. In birds, the relative 
size of the cerebrum is considerably increased, and 
their intelligence is proportionally and noticeably 
higher. From birds we pass to quadrupeds, and 
here is a great increase in the size of the cerebrum, 
and a correspondingly finer intelligence. As we go 
up in the scale of quadrupeds, we find the size of 
the cerebrum increasing faster than the size of the 
body does, until, in the elephant, we find a brain 
weighing eight or ten pounds. The elephant and 
the whale are the only animals whose brains are 
larger than man’s, and even their immense brains are 198 
ORGANS OF CO-ORDINATION. 
much smaller relatively to the size of their bodies. 
The human brain varies in weight in different persons, 
but its average weight is fifty ounces, or about three 
pounds. These facts, then, seem to show a relation- 
ship between the cerebrum and the quality of intelli- 
gence, for the difference in weight of different brains 
is mainly due to the varying size of the cerebrum. 
249. Size of Human Brains.—When we examine 
different brains among human beings, we find the 
same general law holding good. Other things be- 
ing equal, a larger brain signifies a greater mind. 
Thus the brain of Cuvier,* the celebrated naturalist, 
weighed ounces ; that of Abercrombie,f physi- 
cian and philosopher, 63 ounces, and that of Du- 
puytren, surgeon, 62% ounces; while the brain of 
an idiot seldom exceeds thirty ounces in weight. 
Occasionally men have possessed great intelligence, 
and have been found after death to have very small 
brains. An example of this is the brain of a cele- 
brated mineralogist (Haussmann), who is said to 
have been above medium stature. Its weight was 
only 43.24 ounces. In such cases, it is usually found 
that the convolutions are very deep and very much 
curved and turned about, so that there is a greater 
amount of gray matter packed away than would 
have been expected in so small a skull. 
* Baron George Chretien Leopold Frederic Dagobert Cuvier, one 
of the most eminent of modern scientific men (1769-1832), Professor 
of Natural History in the College of France ; generally considered the 
founder of the science of comparative anatomy. 
f John Abercrombie, a distinguished Scottish physician (1781-1844), 
especially celebrated for his metaphysical writings. 
\ Baron Guillaume Dupuytren (1777-1835), during his lifetime con- 
sidered the most eminent surgeon in France ; Professor of Surgery at 
Paris. THE BRAIN. 
199 
250. Effect of Injuries of the Brain.—It has also 
been noticed, from the earliest times, that injuries 
of the brain produce unconsciousness and various 
other phenomena, which indicate that the organ of 
the mind has been injured ; so that, by almost all 
men, the fact that the brain is the seat of the mind 
has been readily acknowledged. In order to deter- 
mine what particular portion of the brain is the 
organ of mental processes, experiments have been 
performed on animals. As has previously been 
mentioned, the cerebrum can not be removed from 
the higher animals without causing their death by 
haemorrhage, but in birds and rabbits, as well as in 
the reptiles, it can be done. If the cerebrum be re- 
moved from a pigeon, then, what is the effect upon 
the intelligence ? 
251. Removal of the Cerebrum of a Pigeon.— 
The bird passes into a condition of stupor, in 
Fig. 6o.—Pigeon, after removal of the cerebrum. 
which he takes no notice of anything about him 
(Fig. 60). It is not that he does not see or hear or ORGANS OF CO-ORDINATION 
200 
feel, for he does have all of these sensations. If 
his foot be pinched, he lifts it up, and then puts it 
down again, and moves uneasily, showing that he 
feels the irritation. His eyes will follow a lighted 
candle, which is moved to and fro, showing that 
he sees it. If a pistol be fired behind his head, he 
looks around, showing that he heard the report, 
and then becomes quiet again, relapsing into his 
condition of stupor. What do these facts indicate ? 
The bird’s senses are perfect; he sees, and hears, 
and feels, but is stupid. All the impressions upon 
his senses convey no idea to him, or rather they 
give rise to no idea. Noises and hurts, which in 
his natural state would frighten him, hardly disturb 
him. If food be put into his mouth, he swallows 
it, but he will make no attempt to feed himself. 
In fact, every action and every response to irri- 
tation goes to show that he has lost his mind ; his 
intelligence is gone; he no longer has the power of 
reasoning on what happens to him. 
252. Disease of the Human Cerebrum.—And 
here, as in the case of the spinal cord, we find 
experiments on human beings provided for us by 
Nature. When the cerebrum of a human being is 
diseased, we find that the mind is affected. This is 
noticeably the case in the disease commonly known 
as softening of the brain. The first symptoms in this 
distressing malady are mental ones. The person 
begins to lose his memory; his friends probably 
perceive it before he does himself; and from this 
first indication of intellectual feebleness the disease 
goes on, often without any disturbance of the nu- 
trition of the body, until the intelligence is com- 
pletely abolished, and the person’s life is a blank. THE BRAIN. 
201 
When the brain of such a person is examined after 
death, the cerebrum is the part found diseased, 
and we see that the gradual impairment and ex- 
tinction of the mind, which we have watched in a 
human being as the result of disease, is really the 
same thing as the sudden destruction of the mind 
which we produce in a pigeon by a surgical opera- 
tion. 
253. Recapitulation.—To recapitulate; the evi- 
dence that the cerebrum is the seat of the intelligence is 
the following: First, we see that in the lower ani- 
mals, as well as in man, the development of the mind 
is proportionate to the development of the cerebrum 
in comparison with the rest of the body. Second, 
that if the cerebrum be removed from an animal, 
the mental faculties are the only ones lost. Third, 
when the mind of a human being is impaired or 
lost, we find a corresponding disease or injury of 
the cerebrum.* 
254. Structure of the Cerebellum.—The gan- 
glion next in size to the cerebrum, and one whose 
functions are of great importance, is the cerebel- 
lum, or little brain (Figs. 57, 58). It is situated be- 
neath the back part of the cerebrum, occupying 
* Also, when the cerebrum is seriously injured, the mental faculties 
are generally impaired. There have been some cases of recovery after 
very severe injuries of the brain. In 1850 a young man in Vermont, a 
farm-hand, was blasting rock, when a tamping-iron, three and a half 
feet long and an inch and a quarter in diameter, was driven through 
his head, entering the left cheek and coming out at the top of the head, 
causing a great loss of brain-substance. He recovered completely from 
the wound, but from a quiet, home-loving, honest lad, he developed 
into a tricky, thieving fellow, of a roving disposition, lived in various 
places in South America and the United States, was subject to epilep- 
tic fits, and died in convulsions in California twelve years after the in- 
jury. 202 
ORGANS OF CO-ORDINATION. 
that portion of the skull immediately behind the 
ears. Its average weight is five and a quarter 
ounces, about one ninth of the whole weight of 
the brain. It is composed of gray and white mat- 
ter, arranged in much the same way as in the cere- 
brum, excepting that the convolutions are smaller 
and dip in deeper, so that in the cerebellum the 
proportion of gray matter is much greater than in 
the cerebrum. This fact, of itself, would indicate 
its importance. 
255. Function of the Cerebellum.—The exact 
function of this part of the brain has not yet been 
determined. There are difficulties in the way of 
experiments upon it, which are not found in experi- 
ments upon the cerebrum. If the entire cerebellum 
be removed from a pigeon, the bird dies from 
hasmorrhage, and nothing can be learned. If the 
greater part of it be removed, proper precautions 
being taken against haemorrhage, very peculiar 
phenomena are presented. The pigeon sprawls 
about in frantic efforts to.get away, but acts like a 
drunken man (Fig. 61). He does not seem to pos- 
sess proper control over his muscles. The muscles 
act perfectly well; there is no paralysis, but the 
harmonious action of sets of muscles is apparently 
interfered with. To move the wings for flying, or 
the legs in walking, requires the consentaneous 
action of many muscles, and this the bird is unable 
to control. 
This experiment, which invariably produces the 
same results, seems to show that the cerebellum in 
some way controls and harmonizes the voluntary 
muscular contractions, or, as the physiologists ex- 
press it, the cerebellum is the seat of the co-ordi- THE BRAIN. 
203 
nating power in voluntary muscular movements. 
This idea was at one time accepted, but it was 
Fig. 6i.—Pigeon, after removal of the cerebellum, 
found that in pigeons, who did not die from the 
operation, the power of co-ordinating their move- 
ments was after a time regained. And this was not 
the result of the healing of the injury, for the lost 
portion of the cerebellum is found on inspection not 
to have been renewed. 
Diseases of this portion of the brain in the hu- 
man being also give contradictory data. Tumors 
and injuries of the cerebellum often occasion diffi- 
culty in muscular co-ordination, but, on the other 
hand, no disturbance in the muscular movements 
has been detected in some cases, where the disease 
of the cerebellum has been very extensive. 
Comparison of the relative development of the 
cerebellum in different animals seems to favor the 
theory proposed. 
All things considered, however, scientific men 204 
ORGANS OF CO-ORDINATION. 
are agreed that the real function of the cerebellum is 
not yet definitely known. 
256. Other Ganglia of the Brain.—Besides the 
cerebrum and cerebellum, there are various ganglia 
of less size, all of which are situated on or near the 
under surface of the brain. Experiments upon these 
are very difficult, and have been hitherto unproduc- 
tive of results. It is an undoubted fact, however, 
that, unless destroyed by loss of blood, an animal 
will continue to live after the cerebrum and cerebel- 
lum have been removed, showing that these latter 
organs are not essential to life. Of the remaining 
ganglia, the tuber'cula quadrigem'ina * are known to 
be the centers by which vision is rendered possible. 
The optic nerves take their origin in these small 
ganglia, and the fact that they receive the impres- 
sions which we call sight is proved in this way: If 
the optic nerve be cut between the eye and the tu- 
bercula quadrigemina, blindness results. The same 
effect is produced by destruction of these bodies, 
the optic nerves remaining uninjured. If, on the 
other hand, the connections between these ganglia 
and the cerebrum be severed, the ganglia and nerves 
remaining intact, sight still remains, and vision is 
also retained, if the cerebrum be removed and the tu- 
bercula quadrigemina left untouched. These things 
are sufficient to show that they are the centers of 
the sense of vision. 
In some one or all of the remaining ganglia, 
with the exception of the medulla oblongata, to be 
hereafter described, the powers of sensation and 
* These small bodies are situated above and in front of the cere- 
bellum, between it and the cerebrum, and so are not shown in any of 
the cuts. THE BRAIN. 
205 
motion reside. This is known from the fact that, 
after the removal of the cerebrum and cerebellum, 
the animal is still capable of sensation and voluntary 
motion; but, if all the ganglia be removed, except- 
ing the medulla, not only does consciousness dis- 
appear, but all sensation and voluntary movements 
cease, the special senses are abolished, and the only 
manifestations of life are the continuance of the 
functions of respiration and circulation, and the re- 
flex movements of the parts connected with the 
spinal cord. 
257. The Medulla Oblongata.—The spinal cord 
passes upward from the spinal canal into the skull. 
Just after entering the cavity of the skull, it be- 
comes somewhat enlarged, and this enlarged por- 
tion is called the medulla oblongata (Figs. 5 7, 58). 
It is about an inch and a quarter long, and three 
quarters of an inch wide, and at its upper extremity 
is merged in other parts of the brain. Imbedded 
in this part of the cord is a small mass of gray mat- 
ter, which is more essential for the actual preserva- 
tion of life than any other portion of the brain. It 
has sometimes been called the “ vital knot.” If this 
be destroyed, all manifestations of life instantly 
cease. The cause of this is the intimate relation 
which this part bears to the function of respiration. 
258. The Medulla Oblongata controls Respira- 
tion.—The movements of respiration are to a cer- 
tain extent under the control of the will, but, under 
ordinary circumstances, we breathe unconsciously. 
Inspiration and expiration take place regularly and 
unceasingly, by night and by day, in our sleeping 
as well as our waking hours. The nervous supply, 
therefore, by which this function is controlled is, 206 
ORGANS OF CO-ORDINATION. 
so to speak, automatic. The requisite movements 
are carried on by reflex action. How is this accom- 
plished ? 
As the processes of repair and waste go on, car- 
bon dioxide and other waste matters accumulate in 
the blood. When this venous blood, loaded with 
impurities, arrives at the lungs, it imparts a peculiar 
stimulus to the large nerves, which are distributed 
to these organs. They convey a sensation to the 
medulla oblongata, and the corresponding motor 
nerves convey the impulse from the gray matter of 
the medulla oblongata, and cause a contraction of 
the muscular walls of the chest. Inspiration then 
takes place, the blood receives oxygen, the air is 
expired again, and the chest-walls remain passive 
until venous blood again accumulates in the lungs 
in sufficient quantity to cause the requisite stimulus 
in the medulla oblongata; and so the process con- 
tinues through a long life, independently of the will 
of the individual. 
259. Automatic Action of the Medulla Oblongata. 
—Respiration, however, is in a measure under the 
control of our will. We can hold our breath, if we 
choose, for a short time; but, with the cessation of 
respiration, the blood becomes more and more 
charged with impurities, until at length a peculiar 
sensation begins to be felt, which we call “ want of 
breath,” or “shortness of breath.” If we still resist 
the desire to inspire, and hold the chest-walls im- 
movable, this sensation increases until it induces the 
most intense suffering, and the will is at length un- 
able to assert its power. The automatic action of 
the medulla oblongata overrides our feeble opposi- 
tion, and we breathe again, in spite of ourselves. It THE BRAIN. 
207 
is a lesser degree of this same sensation, without a 
doubt, which acts as a constant stimulus to the me- 
dulla oblongata, and keeps up the process of respi- 
ration without our consciousness. Now, when the 
portion of the medulla oblongata containing this 
part, called “ the vital knot,” is destroyed, res- 
piration instantly ceases, and the circulation soon 
stops. This is the quickest way known of killing 
animals, and is much used by physiologists, when 
they wish to produce sudden death, without injur- 
ing the blood-vessels or other organs of the body 
on which they wish to experiment.* 
* In the great slaughtering establishments of the West, cattle are 
killed by puncture of the medulla oblongata. Men sfand upon a raised 
platform, and, as the animals pass underneath, penetrate this organ 
with a sharp spear, or with a bullet from a carbine. The matador, in 
the Spanish bull-fights, also aims to strike this vital part, and his repu- 
tation depends upon the success with which he does it. The Spaniards 
execute criminals upon the same plan, by means of the garotte, which 
consists of an iron collar surrounding the throat, with a steel pin pro- 
jecting inward behind. A single turn of a large wheel forces this pin 
into the medulla oblongata and causes instant death. CHAPTER V. 
SPECIAL NERVES.—HYGIENE. 
2oo. Nerves of the Head and Face.—In the 
spinal nerves, we have seen that the motor and 
sensory fibers are mingled, so that each nerve con- 
tains fibers of both kinds. In the nerves coming 
from the brain this is commonly not the case. As 
a rule, some nerves are 
entirely nerves of sensa- 
tion, and others entirely 
nerves of motion, and 
the two functions are 
not united in a single 
trunk. These nerves 
are arranged in pairs, 
like the spinal nerves, 
one going to one side 
of the head or face and 
the other to the other. 
The two most im- 
portant nerves of the 
face are those called 
the trigeminal and the 
facial. The trigeminal 
nerve (Fig. 62) emerges from the skull by three 
openings, being divided into three branches just 
Fig. 62.—Diagram showing the distri- 
bution of the fifth nerve to the face. SPECIAL NERVES.—HYGIENE. 
209 
before it reaches these openings. One branch sup- 
plies the parts surrounding the eye, the forehead, 
and the inside of the nose; the second comes out 
just below the eye, after sending branches to the 
teeth of the upper jaw, and supplies the cheek, 
the upper lip, and the outside of the nose; while 
the third comes out at a point near the front of the 
lower jaw, and supplies the chin and lower lip, be- 
sides having sent branches to the teeth and tongue, 
before emerging from 
the jawbone. These 
nerves are the great 
nerves of sensation of 
the face, and are gener- 
ally considered to be 
the most exquisitely 
sensitive nerves in the 
whole body. They are 
often the seat of neu- 
ralgia, and give rise to 
the most intense and 
intolerable suffering. 
The facial nerve 
(Fig. 63) is the motor 
nerve of the face; it 
emerges from the skull 
just below the ear, and, passing forward through 
the parotid gland, is distributed to all the muscles 
of the face. Paralysis of this nerve is far from un- 
common, and produces a most singular and charac- 
teristic effect upon the countenance. Exactly one 
half of the face loses all expression, as much as if 
dead, and the contraction of the muscles of the op- 
posite side, not being in any way counteracted, pro- 
Fig. 63.—Diagram showing the distri- 
bution of the facial nerve to the face. ORGANS OF CO-ORDINATION. 
210 
duces dreadful, though often ludicrous, distortion 
of the features. This form of paralysis often occurs 
among hackmen and others who are exposed to 
stormy weather. If a strong wind, particularly 
when accompanied by snow or sleet, be allowed to 
beat upon the side of the face, there is great danger 
of paralysis of the facial nerve. Such exposure of 
the place where this nerve emerges from the skull 
should be carefully avoided. 
261. The Sciatic Nerve.—Each limb of the body 
is supplied by large nerve-trunks, which, as a rule, 
follow very nearly the course of the arteries. The 
largest nerve of the leg, however, runs down be- 
hind the limb, while the femoral artery runs down 
the front of the thigh. This nerve is known as 
the sciat'ic, and its branches extend to the foot. 
It is this nerve which, when pressed upon in sitting, 
gives rise to the sensation commonly described as 
the “ foot being asleep.” 
262. Importance of Reflex Action.—It is impor- 
tant to call attention to the fact that reflex action has 
a great deal to do with our health and safety, even 
when the spinal cord and brain are in perfect con- 
dition. People in general are hardly aware how 
much they owe to this property of the nervous sys- 
tem in time of danger. Familiar illustrations are 
found in the rapid recovery of the bodily equilib- 
rium, when the foot has slipped ; in the involun- 
tary start and assumption of a position of defense, 
when a horse and wagon suddenly run upon one in 
the street; in the start of the body at a sudden 
noise; in the instantaneous withdrawal of a portion 
of the body when it is burned ; in the winking of 
the eyelids, particularly at indications of danger ; SPECIAL NERVES.—HYGIENE. 
211 
and in hundreds of daily actions, which follow so 
instantaneously upon the application of a stimulus, 
that the thought, or mental appreciation of the 
stimulus, does not come until after the reflex action 
has already taken place.* 
When we consider the immense number of such 
actions which take place every hour of the day. and 
the stupendous work of nutrition, with its compli- 
cated phenomena, all going on outside of our con- 
trol, we see that in all probability the greater part 
of the nervous force expended in the body goes to 
produce involuntary movements, and to control and 
preserve the health and integrity of our organism 
in spite of ourselves. It is a suggestive thought 
that, much as we appear to be our own masters, 
independent as we seem to be of the outside world, 
we are really ruled by the general vital forces 
which equally rule all animals and even plants, 
upon which we are all equally dependent, and over 
which what we call “ we ” have almost as little con- 
trol in ourselves as in the lion that roams the des- 
ert or in the grass that grows beneath our feet. 
263. Education of the Nervous System.—The 
hygiene of the nervous system has to do mainly with 
the problem of education, and with the over- or un- 
der-use of its parts. Education is a broad subject, 
and can not be taken up here, but it is undoubtedly 
* It is related of a distinguished chemist that a glass vessel once 
exploded in his hands and was blown into a thousand pieces. His 
hands were severely lacerated, and he at first feared that his sight was 
destroyed ; but on examination it was found that he had closed his eye- 
lids involuntarily at the instant of the explosion, and, although the lids 
had been wounded in many places by the flying bits of glass, the eyes 
were uninjured. The rapidity of such reflex action far surpasses that 
of any voluntary movement. ORGANS OF CO-ORDINATION. 
212 
true that in the future much more attention will be 
paid than in the past to the physical conditions 
which underlie all development and training of the 
mental powers. It is known that repetition of the 
same process in any portion of the nervous system 
renders it every time more and more easy. The 
result of such repetition is what we call habit. The 
more impressible and easily stimulated the different 
parts of the nervous system are, therefore, the more 
readily habits will be formed and the more firmly 
they will become fixed. Now, the cells and fibers 
of the nervous system of young and growing ani- 
mals, like those of their muscular system, are espe- 
cially soft and yielding, and, as they are constantly 
growing, the changes in them are more frequent, 
and they are much more easily influenced by any 
stimulus than those of adults. Consequently chil- 
dren and youths are especially liable to form habits, 
and, in order to prevent the formation of bad ones, 
they need the guidance and protection of older per- 
sons. The experience of the young is not wide 
enough to inform them correctly of what is good 
and what is bad, nor is it, in most cases, sufficient 
to enable them to appreciate the wisdom of the 
advice or commands of older persons. For these 
reasons it is necessary, in the training of the young, 
to require what often seems to them unreasonable, 
and to forbid things with what may seem to them 
foolish pertinacity. It is this readiness with which 
habits are formed in the young, and the firmness 
with which they become fixed, that render it so 
dangerous for them to indulge in sensual gratifica- 
tions, such as the drinking of liquids containing 
alcohol, or to join in games which excite the selfish SPECIAL NER VES.—H YGIENE. 
213 
emotions in a high degree, such as lotteries and 
gambling. 
It is this ease of habit-forming in the young, too, 
that renders childhood and youth the desirable time 
for both mental and physical training. In fact, the 
nervous system is, at this time, so impressionable that 
the training will take place inevitably, whether it is 
directed or not, and the success or failure of adult 
life is generally determined by the conditions under 
which the years below twenty have been passed. 
264. Importance of exercising the Brain.—The 
nervous system, like the muscular, must be suffi- 
ciently exercised, in order to remain vigorous and 
healthy. If the brain be allowed to remain indo- 
lent, the faetdties of memory and attention, the 
power of concentrating the thoughts, will be con- 
siderably weakened. It will be found that even 
the inactivity of a few weeks’ vacation will render 
it a matter of some difficulty at first to keep the 
brain at work at one’s ordinary duties. Judicious 
exercise also will strengthen special mental facul- 
ties, just as proper training will develop muscular 
power. The retentiveness of the memory may be 
immensely increased, and the facility with which 
the daily mental labor of the professional man is 
performed, together with the increased efficiency 
as age advances, shows the effect of directing the 
nutritive processes constantly in the same direction. 
In fact, this tendency is so strong that specialists, 
all of whose energies for many years are directed 
upon a particular subject, are very apt to become 
narrow-minded or “ lop-sided,” and unable to see 
more than one side of any subject, and that some- 
times the least important one. 214 
ORGANS OF CO-ORDINATION. 
265. Danger of Over-Exercise.—On the other 
hand, too much exercise is as injurious as too little. 
All brain-work, as well as muscular work, involves 
a waste of tissue. As we are thinking, our brains 
are wearing out. And while this organ is actively 
employed, the waste of tissue is greater than the 
repair. When this excess of waste has reached such 
a point that the proper working of the brain is inter- 
fered with, we begin to feel incapable of further 
study, the attention begins to waver, problems seem 
difficult that at other times would be easy, and 
perhaps the memory is at fault. Such a condition 
demands imperative rest, and this rest is obtained 
by sleep. 
266. Sleep.—During sleep, the repair of all the 
tissues goes on with great rapidity. As the body is 
inactive, even the brain being in sound sleep en- 
tirely unoccupied with thought, the waste of the 
tissues is very small, almost the whole of it being 
the result of the organic processes of circulation, 
respiration, and digestion. In all of these organic 
processes, which must be practically continuous, 
rest is obtained at short intervals, the activity of 
the organs concerned in them being intermittent, 
and, although the intervals of rest are very short, 
they are so numerous that they make up together 
about half of the twenty-four hours. But the mus- 
cular and nervous systems have no such frequent 
intervals of rest during waking hours, the brain, in 
particular, being constantly active, so that their rest 
has to be taken continuously in the form of sleep. 
During sleep, therefore, the repair of tissue runs 
vastly ahead of the waste, and the exhausted parts 
have their vigor and irritability rapidly restored. SPECIAL NER VES.—H YGIENE. 
215 
As the special senses and the sensitiveness of the 
muscular and nervous systems had become dulled 
and torpid because they were wasting away, so now, 
as they are built up again, their sensitiveness re- 
turns, and slight stimuli are sufficient to arouse them 
into activity. We then wake up. Even the morn- 
ing light may produce a sufficient effect upon the 
eye, through the closed lids, to waken the sleeper, 
and he rises refreshed for the work of another day. 
The best time for sleep is night, because it is 
dark and quiet; the natural stimuli of the eyes and 
ears are absent, and therefore rest can be obtained 
with the least likelihood of being broken. It is a 
good rule for all persons to go to bed before mid- 
night, and rise within ten minutes after waking in 
the morning. The amount of sleep required by 
each individual must be determined by himself 
from experience. For most persons eight hours is 
not too much, and many can do with less.* Chil- 
* Marvelous stories are told of persons who can get along with very 
little sleep. In most cases, if sleep is dispensed with at one time, it 
must be made up at another, and some people possess the faculty of 
falling asleep at odd moments, and making up, by what are sometimes 
called “ cat-naps,” for the loss of regular sleep. Thus, Napoleon Bona- 
parte is said to have been satisfied with four hours’ sleep in the twenty- 
four ; but this only refers to the time he spent in bed. He was in the 
habit of sleeping on horseback during a march, and his traveling-coach 
was made expressly so that the interior could be arranged as a bed. He 
often fell asleep, too, for a few minutes at a time, in his study, with his 
head resting on his arms on a desk in front of him. It maybe doubted 
whether any person could live long with only four hours’ sleep a day. 
The Chinese sometimes punish criminals by confinement in a cage 
where they can neither stand up nor sit or lie down. Attendants are 
stationed to prevent the miserable men from falling asleep ; for even 
under such conditions exhaustion brings on sleep. The unfortunate 
men are pricked and pinched, and by various means of torture kept 
awake until, as a rule, in eight or ten days, they die raving maniacs. 216 
ORGANS OF CO-ORDINATION. 
dren need more, in proportion to their fewness of 
years, and old people sometimes need less, because 
of their comparative inactivity during their waking 
hours. 
267. Abuse of the Nervous System.—A word of 
caution should be spoken about the various forms 
of indulgence which affect the sympathetic system 
of nerves. These include all those forms of sensual 
gratification which are accompanied by a high de- 
gree of physical pleasure, followed by a more or 
less protracted period of depression. This depres- 
sion, an instance of which is seen in the reaction 
following intoxication, is the result of a great shock 
and consequent great waste of tissue in the sympa- 
thetic nervous system. Recovery from such shocks 
is very slow. The sympathetic ganglia have to do 
with the important function of nutrition. They lie 
at the very foundation of life in our bodies. Their 
ordinary duties are severe, and about all they can 
attend to properly. Therefore, any great shock to 
this part of the nervous system affects the very cen- 
ters of life. This is the reason of the “ breaking 
up,” as it is called, which results from the various 
forms of dissipation. This word “ dissipation ” is 
well used for such acts as are commonly included 
under this head, as all kinds of debauchery, abuse 
of the digestive organs, late hours, insufficient sleep 
and relaxation, etc., dissipate nervous force with 
frightful rapidity. PART V. 
ORGANS OF PROTECTION. 
CHAPTER I. 
THE SKIN. 
268. The Skin.—The skin, with its appendages, 
is a complex organ, and has many functions. It 
serves for protection, contains nerves of sensation, 
secretes, absorbs, and excretes, and its functions are 
so necessary to life that, if in any way it be rendered 
unable to perform its duty in the organism, death is 
the result. 
269. Structure of the Skin.—The skin is com- 
posed essentially of two layers, one called the cuticle 
or epidermis, and the other the cutis or derma (Fig. 
63).* The former is the outside layer, and the lat- 
ter the inside. The epidermis consists of small, flat- 
tened, dry scales, and receives the brunt of injuries 
and abrasions. The thickness of this layer is shown 
in a blister, the epidermis being there separated 
from the layer beneath by the fluid which fills the 
vesicle.f The inner layer, or derma, constitutes 
* Cutis is the Latin for skin, and cuticle means little skin ; derma 
is the Greek for skin, and epidermis means the outer layer of the skin, 
or. literally, “ upon the skin.” 
f Vesicle is from the Latin, and means a bladder, which a blister 
somewhat resembles. 218 
ORGANS OF PROTECTION. 
what is sometimes called the true skin. This layer 
alone contains nerves, blood-vessels, hair-bulbs, and 
Hair. 
Epidermis. 
Pigment-cells. 
Papillae. 
Derma. 
Sweat-glands. 
Fatty tissue. 
Fig. 64.—Diagram representing a vertical section of the skin. Attached to 
the hair are two sebaceous glands. 
the other appendages of the skin. It is made up of 
strong interlacing fibers of connective tissue, which 
form a firm, close covering for the delicate tissues 
beneath. This layer varies in thickness in different 
parts of the body, from one fiftieth to about one sixth 
of an inch. For instance, the skin of the eyelid is 
very thin, while that of the small of the back is the 
thickest in the body. 
270. The Derma. — The under surface of the 
derma is merged in the loose connective tissue 
which lies between the skin and the flesh. It is in 
this loose tissue that fat accumulates, and, in conse- 
quence of its peculiarly loose and flexible structure, 
the skin can be moved easily in any direction, slip- 
ping or gliding, with no pain and no disagreeable 
sensation, over the tissues immediately beneath it. 
The upper surface of the derma is covered with THE SKIN. 
219 
little elevations, called papil'lce, which, on an aver- 
age, are about of an inch in length, and j-g-jy of 
an inch broad at the bottom. They are somewhat 
conical in shape, and in their interior are found the 
ends of sensitive nerves. In some parts of the 
body they are scattered irregularly on the surface 
of the derma, while in other regions they are ar- 
ranged in rows, and produce the appearance of 
small parallel ridges on the surface of the body. 
This latter arrangement is most distinctly to be 
seen on the palm of the hand and fingers, and in 
these parts also the sense of touch is most highly 
developed. 
271. The Epidermis.—The epidermis lies in im- 
mediate contact with the derma, its under surface 
being accurately molded to fit the papillae. But, in 
the under portion of it, the portion into which the 
papillae project, the scales, instead of being flat and 
hard, are rounded and soft, and contain a certain 
amount of coloring-matter, in the form of small, 
dark granules.. As this part of the epidermis 
varies in color and thickness, so the complexion 
of the person varies.* In the negro, these pig- 
ment-cells, as they are called, are very dark and 
numerous, and there are all gradations in the 
amount of the coloring-matter in different persons, 
from the coal-black African to the albino, in whom 
there is no color at all, except the red tinge given 
by the blood. 
* This layer of pigment-cells seems to protect the parts beneath 
from the action of the sun. The natives of all tropical countries are 
dark, and exposure to the sun’s rays, even in our climate, tans the skin 
to a darker hue. Sometimes this effect of the sun is more noticeable 
in particular spots, producing what are known as freckles. ORGANS OF PROTECTION. 
220 
272. The Nails.—Near the ends of the fingers 
and toes the skin takes on a peculiar appearance. 
The epidermis is very closely applied to the derma, 
with no colored cells between them, and the scales 
of which it is composed are singularly dry and 
hard, and semi-transparent. These peculiar growths 
are called the nails. The part of the finger from 
which they grow is called the root of the nail, and 
the nail grows both in length and thickness. It is 
formed by the continual pushing forward of new 
cells, both from the root and from the under sur- 
face. The growth from the root makes it grow in 
length, while the addition of cells on the under 
surface renders it thicker at the forward end than 
it is near the root. The nails were probably once 
a means of defense and offense, when men were in a 
low, barbarian state; but, at the present day, their 
chief value appears to be for ornament, and as a 
support for the pulp of the finger.* 
273. The Hair.—The hairs are peculiar growths 
of the skin. At certain points the surface of the 
skin seems to dip inward, forming a deep pit or 
pocket, at the bottom of which is a little projection 
or papilla. From this papilla the hair grows, and, 
emerging from the pocket, attains in some parts of 
the body a considerable length.f The body, or 
shaft, of a hair consists of cells, flattened and hard, 
but through its center, from one end to the other, 
* The nails are of special use in the way last mentioned. The 
finger-tips are extremely sensitive, and the hard, stiff nail serves as a 
backing against which it can be pressed by the objects it touches. In 
this way the nails increase materially the delicacy of touch. 
f Instances have been known of women with hair six or seven feet 
in length, and of men whose beards measured nearly as much. Such 
cases, however, are very rare. THE SKIN. 
221 
runs a hollow canal, filled with pigment-cells. These 
cells, according to the amount of the coloring-mat- 
ter in them, give the hair the appearance known as 
black, brown, gray, auburn, etc. Almost the whole 
surface of the body is covered with hair, excepting 
the palms of the hands and the soles of the feet, but 
most of it is of a soft, downy variety, which is not 
visible without close observation. 
274. The Sebaceous Glands.—There are certain 
small glands, situated in the substance of the derma, 
which are called the sebaceous*glands, or sometimes 
the oil-glands. They are composed of minute sacs 
lined with epithelial cells, which constantly secrete 
and pour out of their mouths a whitish, tallow-like, 
fatty substance. Most of them empty into the hair- 
pits or follicles,f as they are called, and thence their 
secretion runs along the hair, and out on the sur- 
face of the body. They aid in keeping the hair and 
skin soft and flexible. Sometimes the opening, by 
which the secretion of the gland is discharged, 
becomes obstructed, and the gland still goes on 
secreting. In such a case, a swelling makes its ap- 
pearance at the seat of the trouble, and the irrita- 
tion of the retained secretion causes an inflammation 
to set in, which continues until the contents of the 
inflamed sac are discharged, or let out by the prick 
of a needle. This is the cause of the unsightly lit- 
tle pimples or boils which occasionally come on the 
end of the nose, and give rise to great annoyance.:}: 
* Seba!ceous, from the Latin sebum, meaning fat, or tallow, 
f Fol'licle, from the Latin word folliculus, meaning a little sack or 
pouch. 
\ There are many of these sebaceous glands about the end of the 
nose, and the little openings, by which their secretion reaches the sur- 
face, often become obstructed by dirt, so that the secretion accumulates 222 
ORGANS OF PROTECTION. 
275. The Sweat-Glands.—There are still other 
glands in the skin which have a very important 
part to play in the maintenance of life itself. These 
are the sweat-glands, or perspiratory glands. They 
are situated either in the lowest layer of the derma 
or in the loose connective tissue just beneath it. 
The mass of one of these glands is convoluted— 
i. e., it is made up of a long tube, rolled about and 
twisted into a ball. This tube is lined with epithe- 
lial cells, like the interior of all glands, and, after 
leaving the convoluted portion, it passes in quite 
a direct course through the derma, and then in 
a spiral course, like the thread of a corkscrew, 
through the epidermis, on the surface of which it 
opens. If one of these little glands be unrolled, 
and its tube stretched out, it is found to be about 
tV of an inch in length, while its diameter is about 
of an inch. Notwithstanding their minute size, 
however, there are so many of them that their se- 
creting surface is enormous. They are least nu- 
merous on the neck and back, where there are 417 
to the square inch, and they are found in the great- 
est numbers on the palm of the hand, where there 
are no less than 2,700 of them to the square inch. 
The total number is said not to be less than 2,300,- 
000, and by a simple calculation it will be found 
that the total length of these minute tubes, if care- 
fully unrolled and placed end to end, would be 
about two miles and a half! 
in the interior. When this is squeezed out, it looks like a small, white 
worm, the dirt at the outer end resembling the head. Hence the term 
“black-heads,” To be sure, there are sometimes little worms found 
imbedded in this secretion, but they are only to be seen with the mi- 
croscope. CHAPTER II. 
FUNCTIONS OF THE SKIN—HYGIENE. 
276. Effects of Pressure on the Skin.—It is evi- 
dent, without demonstration, that the skin protects 
tiie parts beneath it. In the performance of this 
function, it sometimes resents too great pressure, or 
unequal pressure, from outside. In such cases the 
skin becomes thicker in spots where the pressure 
occurs. If the epidermis only is affected in such 
cases, and there is merely an increased production 
of epidermal cells from beneath, the skin becomes, 
as we say, callous. If, however, the derma be affect- 
ed, the papillag become enlarged and project above 
the surface, warts are produced, and, where both 
forms of growth take place, we have corns. Press- 
ure is undoubtedly not the only cause of the devel- 
opment of these unpleasant diseases, but it is one 
cause. But the origin of warts, in particular, is 
generally obscure. 
277. Animal Heat.—The skin also has an impor- 
tant function to perform in maintaining a uniform 
temperature in the body. Every one knows that a 
living body is warm. Why is it so? There has 
been much discussion on this point, and many theo- 
ries proposed regarding it. When oxygen was first ORGANS OF PROTECTION. 
224 
discovered, Lavoisier* supposed that the process oi 
respiration was a process of combustion; that the 
oxygen which entered the lungs in the air united 
directly with the carbon in the venous blood, and 
produced carbon dioxide. In ordinary flame, this 
is the chemical change which accompanies combus- 
tion. The oxygen of the air unites with the carbon 
of the tallow or oil and produces carbon dioxide, 
the hydrogen of the oil also uniting with oxygen to 
produce water. Thus we get, as a result of com- 
bustion, a disappearance of oxygen and a produc- 
tion of carbon dioxide and water. Now, in the air 
which passes in and out of the lungs, we find the 
same thing. Oxygen passes in, and carbon di- 
oxide and water, in the form of vapor, come out. 
What more natural, then, than to conclude that 
respiration was combustion, and the lungs a sort of 
stove by which the heat of the body was kept up ? 
It was soon found, however, that the lungs were 
no warmer than the rest of the body, and particu- 
larly that the blood contained carbon dioxide be- 
fore it reached the lungs, and took away free oxygen 
from them. These facts showed conclusively that 
the change did not take place in those organs. 
The great chemist, Liebig,f then changed the the- 
* Antoine Laurent Lavoisier, a celebrated French chemist (1743- 
1794). He first discovered the composition of water, and invented a 
chemical nomenclature which lasted for more than fifty years. He was 
guillotined during the French Revolution, because, twenty years before, 
he had been a tax-gatherer under the monarchy. 
f Baron Justus von Liebig, a renowned German chemist (1803- 
1873), Professor of Chemistry at Munich. He was the greatest chem- 
ist of his time, made many practical applications of chemistry in agricul- 
ture and the arts, and was one of the founders of the science of organic 
chemistry. FUNCTIONS OF THE SKIN.—HYGIENE. 
225 
ory, by supposing that the combustion took place, 
not in the lungs, but in the tissues generally through- 
out the body, and this theory was for a long time ac- 
cepted. It is now giving way, however, as it has 
been found that many other chemical processes, be- 
sides the union of carbon and oxygen, give forth 
heat, and that the amount of oxygen inhaled with 
the breath hardly ever corresponds with the amount 
contained in the carbon dioxide expired. It is now 
considered that the heat of the body is the result, not 
of one class of chemical phenomena, but of all the 
molecular changes and combinations which are con- 
stantly taking place in all parts of the body. 
278. Normal Temperature of the Human Body. 
—The temperature natural to any animal is found 
to be such that, if the blood be made very much 
cooler or very much warmer, it is fatal to life. The 
proper temperature of the interior of the human 
body is about ioo° Fahr. On the surface, of course, 
some parts are cooler than others, according to the 
degree of exposure to which they have been sub- 
jected. Physicians usually take the temperature of 
patients by placing the bulb of a thermometer in 
the armpit, and the instrument in this spot gener- 
ally registers about Fahr. The normal tem- 
perature often varies -|0 or i° from this standard, ac- 
cording to the time of day or night, and according 
to the sleeping or waking condition of the person. 
279. Great Variations in External Temperature. 
—Now, if the blood be cooled much below this 
point, say down to 8o°, death takes place; equally 
so if it be heated to a temperature of 1130. In the 
former case, the person is said to have been frozen, 
for the temperature can not be reduced to this point 226 
ORGANS OF PROTECTION. 
unless by exposure to a very frigid atmosphere; 
and, in the latter case, he is said to die of sunstroke, 
because such a temperature is rarely induced, ex- 
cepting in extremely hot weather. 
But persons are often exposed to a temperature 
of io° or 20° below zero, and of from ioo° to 130° 
above zero. The latter figures, perhaps, require 
a word of explanation. We are apt to think of the 
temperature to which we are exposed in a hot sum- 
mer’s day as the same which we find registered by 
a thermometer hanging in a sheltered spot. This 
is an incorrect way to estimate it. Many of us, 
perhaps most of us, spend some time every day in 
the direct rays of the sun, and it is no uncommon 
thing for a thermometer placed in the same situa- 
tion to register 130°. How, then, are we enabled 
to resist such extremes of cold and heat, and main- 
tain our bodily temperature almost unchanged ? 
280. Effect of Cold on the Body.—When the 
body is exposed to a low temperature, and the sur- 
face is being continually cooled by radiation, the 
first effect, as the cold reaches the tissues just un- 
der the skin, appears to be a stimulating one ; the 
processes of nutrition, of cell destruction and for- 
mation, take place with greater rapidity, and there- 
fore more food is required to supply the waste. 
We all know that in cold weather our appetites are 
more keen, and, if we digest more, we must waste 
more, or else accumulate material in our bodies. 
This latter phenomenon does take place to some 
extent, and most persons gain flesh during cold 
weather.* Now, these changes in nutrition, with 
* Cold weather produces a craving for fatty foods. The Esquimaux 
eat enormous quantities of blubber. Dr. Hayes, the Arctic explorer, FUNCTIONS OF THE SKIN.—HYGIENE. 
227 
increased activity, give rise to an increase of tem- 
perature, and, up to a certain point of exposure, this 
increase of heat is sufficient to balance the increased 
radiation. When the radiation becomes excessive, 
and the greatest activity of the bodily functions is 
insufficient to produce enough heat to compensate 
for it, the blood begins to grow cool, and the symp- 
toms of drowsiness and stupor come on, which are 
the precursors of death. 
281. Effect of Heat on the Body.—On the other 
hand, when the temperature is high, the tendency 
to the accumulation of too much heat in the body 
is kept down partly by a diminution of activity in 
the nutritive processes, and partly by the action of 
the perspiratory glands. In hot weather, the nu- 
tritive processes go on much more slowly than in 
cold, we eat much less food, most of us lose flesh, 
and the production of animal heat in the interior 
of the body is thus very much reduced. But this 
reduction is not sufficient to guard us against the 
harmful effects of a very high temperature. If cold 
becomes too great to be resisted by the ordinary 
forces at work within the body, we put on addi- 
tional clothing, build ourselves fires, shelter our- 
selves in houses, etc., and thus keep warm. But in 
hot weather, if we had no perspiratory glands, we 
should be badly off indeed. 
282. How the Temperature of the Body is regu- 
lated.—The way in which these glands regulate the 
temperature of our bodies is by covering the sur- 
states that his men often drank clear oil with great relish, and the 
Laplanders are said to be fond of tallow-candles. Even in our own 
climate, fried articles of food, which contain a good deal of fat, are 
palatable in winter, but very distasteful in warm weather. 228 
ORGANS OF PROTECTION. 
face of the skin with a watery fluid, whose evapora- 
tion continually abstracts heat. Evaporation con- 
sists in the change of a liquid into vapor. The 
evaporation of any liquid causes a diminution of 
temperature in whatever lies in contact with it. 
Liquids which evaporate very rapidly, like ether, 
produce a very striking sensation of cold, and may 
even be used, in the form of spray, to freeze a por- 
tion of the body. Now when the surface of the 
body is heated, the vaso-motor nerves are some- 
what paralyzed, and an unusual flow of blood takes 
place to the capillaries of the skin. A great flow 
of blood to a gland causes an increased secretion, 
and accordingly the perspiratory glands immedi- 
ately begin to pour forth their peculiar secretion. 
The perspiration is composed of water and salts, 
containing about per cent of water. This water 
evaporates rapidly, and abstracts so much heat that 
the temperature of the body is kept at its normal 
standard. 
283. Amount of Perspiration.—The secretion of 
the perspiration takes place constantly. Under or- 
dinary circumstances, its amount is so small that it 
does not collect in drops, but evaporates as soon as 
it reaches the surface. This is called the “ insen- 
sible perspiration,” and takes place at all times. Al- 
though so gradually secreted and so quickly evap- 
orated as to be unperceived by the individual, its 
daity amount is surprisingly large. Lavoisier and 
Seguin have found it to be a little less than two 
pounds. This amount is immensely increased when 
the body is exposed to an elevated temperature, and 
the perspiration begins to run from the pores in 
streams. It then often rises to the amount of a FUNCTIONS OF THE SKIN.—HYGIENE. 
229 
pound an hour, and, as this great loss of fluid from 
the body has to be resupplied from without, such 
excessive perspiration is followed by excessive thirst. 
284. Exposure to Dry Heat.—In order for evap- 
oration to take place rapidly, the air must be dry 
enough to absorb the vapor into which the water 
passes. If the air be very dry, and contain very 
little water, so that it is prepared to absorb an im- 
mense amount of it, the human body can endure 
without injury an incredibly high temperature. 
Human beings have remained in ovens heated to a 
temperature of from 350° to 6oo° Fahr., and re- 
mained there while eggs and even beefsteaks were 
cooked by their side.* 
285. Exposure to Moist Heat.—If, on the other 
hand, the air be already so saturated with watery 
vapor that it can not take up much more (for its 
capacity in this respect is limited), any great rise in 
temperature causes extreme discomfort. It is on 
account of this difference in the moisture of the 
atmosphere, and consequent diminution or increase 
of evaporation, that our physical comfort varies so 
much on different days, when the thermometer reg- 
isters the same temperature. For this reason, also 
(the moister atmosphere), a temperature of 85° is 
almost unendurable in London, while in New York 
it is usually borne without discomfort. 
* “ The workmen of the sculptor Chantrey were in the habit, accord- 
ing to Dr. Carpenter, of entering a furnace in which the air was heated 
up to 350° ” (Dalton). A public performer, named Chabert, who called 
himself the “ Fire-King,” is said to have exposed himself to a tempera- 
ture of 6oo°, and remained in an oven heated to that degree while a 
beefsteak was cooked by his side. In such experiments care has to be 
taken that no metal, or other good conductor of heat, comes in contact 
with the body, for if it does it will cause frightful burns. 230 
ORGANS OF PROTECTION. 
286. Respiration and Absorption through the 
Skin.—There is also a certain amount of what 
might be called respiration going on through the 
skin—i. e., it has been shown, by inclosing one of 
the limbs in an air-tight case, that the contained air 
loses oxygen and gains carbon dioxide, showing 
that an interchange of those gases takes place 
through the skin, as well as through the lungs.'" 
It is also a fact, well known to physicians, that the 
skin possesses the property of absorbing various 
substances placed in contact with it.f 
The skin is thus seen to be an exceedingly com- 
plex organ, and to possess many very important 
functions. There are certain peculiarities attend- 
ing injuries and diseases of the skin which have 
led many physiologists to think it has important 
functions not yet discovered.^: 
The hygiene of the skin has mainly to do with 
the questions of how to keep it cleansed from im- 
purities, and how to regulate its temperature—i. e., 
with bathing and clothing. 
* The amount of carbon dioxide thrown off by the shin is esti- 
mated at about one thirtieth of that exhaled from the lungs. 
f Medicines are sometimes administered by rubbing them into the 
skin. Castor-oil rubbed over the stomach will produce a medicinal 
effect, and so will mercury. Infants who were too much exhausted by 
disease to eat, or whose stomachs refused to retain food, have been 
saved from death by rubbing nutritive substances, oils, etc., upon the 
surface of the body. 
J When the surface of the body is completely covered with a coat- 
ing impervious to air, death ensues very rapidly. At the coronation 
of Giovanni de’ Medici (1475-T521) as Pope Leo X, a little boy was 
covered with gold-foil to represent a cherub, and add to the splendor 
of the ceremonies. He became almost immediately ill, however, and, 
in spite of all that was done, died in a few hours, because the gold and 
varnish were not removed. FUNCTIONS OF THE SKIX.—HYGIENE. 
231 
287. Necessity of cleansing the Skin.—The im- 
purities on the surface of the skin come mainly from 
three sources : 1. The perspiration contains a small 
amount of solid matter, mostly mineral, which is 
deposited upon the skin and left there as the water 
evaporates. 2. The fatty secretion of the sebaceous 
glands is constantly being poured out in small quan- 
tity, and dries upon the surface. 3. The epidermal 
scales in the outer layer of the skin are being con- 
tinually shed, pushed off, as it were, by the cells 
developing under them, and most of them fall away 
in the form of a fine, branny dust, which clings to 
the under-clothing, and is brushed and washed from 
other parts of the body. A certain amount of this 
refuse epidermis is caught in the drying perspira- 
tion and sebaceous secretion, and so remains, as it 
were, glued to the surface. These different impuri- 
ties tend to choke the mouths of the perspiratory 
and sebaceous glands, and prevent their free action. 
The surface of the body must be kept free from 
such accumulations. 
Much obscurity has been unnecessarily thrown 
around the subject of the ordinary bath. The rules 
regarding it are in reality few and simple. The dis- 
cussions mainly relate to the time, duration, and 
temperature of the bath, and the results may be 
summed up thus : 
288. Effect of a Cold Bath.—The first effect of a 
cold bath is to produce a shock to the nervous sys- 
tem, resulting in the contraction of the blood-vessels 
at the surface of the body. This shock in a healthy 
person is soon followed by a reaction, in which the 
heart acts with more vigor than usual, and the con- 
tracted blood-vessels are again filled with blood. 232 
ORGANS OF PROTECTION. 
The surface of the body then becomes ruddy or 
rosy, and a pleasurable glow is felt by the bather. 
The bath should end while this glow of reaction 
continues, for, if it is allowed to pass away, it is 
succeeded by a feeling of lassitude and depression, 
which may last for the rest of the day, and indicates 
a certain degree of exhaustion of the nervous sys- 
tem. The after-glow may be increased, and the 
good effect of the cold bath enhanced, by a brisk 
rubbing of the surface with the hands or a towel. 
289. Effect of a Warm Bath.—The first effect 
of a warm bath is to dilate the superficial blood- 
vessels and cause a flow of blood to the skin. This 
produces a general relaxation of the pores of the 
glands, tends to increase their activity, and in 
weakly persons there is slight stimulation of the 
nervous system. After such a bath, the skin being 
full of blood and in a relaxed condition, exposure 
to the cold air is dangerous, and the bather should 
not go out-of-doors until the surface of the body is 
perfectly dry, and any feeling of languor has disap- 
peared. 
290. Rules for Bathing.—Briefly stated, then, 
these are the rules for guidance in the bath : 
Do not bathe within three hours after a meal, as the 
change in the circulation produced by the change 
in temperature of the surface of the body interferes 
with the proper distribution of blood in the digest- 
ive organs. 
Do not bathe in cold water, if you have found by 
previous trials that you always have a chilly feeling af- 
tenvard. This is a matter to be determined wholly 
by personal experience, and, when any person finds 
that a particular kind of bath makes him uncom- FUNCTIONS OF THE SKIN.—HYGIENE. 
233 
fortable afterward, it is the part of prudence to 
it thenceforth. As a general rule, it may be 
stated that a vigorous person will feel better after a 
cold bath, and a feeble person after a warm one, if 
not too prolonged. 
Do not remain in the bath too long. If you feel 
chilly when you come out, the bath will do you 
more harm than good. As a general rule, from ten 
to fifteen minutes is long enough for a warm bath, 
and five minutes for a cold one. 
291. Washing the Hands and Face.—The hands 
and face are washed more frequently than any other 
part of the body, because they are more exposed 
and become dirty sooner. If they can be kept clean 
with water alone, soap should be avoided, because 
it unites with the fatty matters on the surface, a cer- 
tain amount of which is natural and necessary to 
keep the skin soft and pliable. Soaps that contain 
an excess of alkali * are particularly injurious, be- 
cause they not only remove too much of the seba- 
ceous secretion, but irritate the surface and even 
produce eruptions. After the hands have been 
washed, especially in cold weather, they should be 
carefully and thoroughly dried before exposing 
them to the cold air. It is the neglect of this pre- 
caution, together with the excessive use of soap, 
that causes “ chapping ” of the hands. The soap 
removes the fatty matter from the epidermis, thus 
depriving it of its pliability, and the water, espe- 
* Soap is made by boiling fat with potash or soda ; the former 
makes soft soap and the latter hard soap, such as is commonly used in 
the toilet. If the proportions of these ingredients are not precisely 
right, there will be an excess of one of them in the product, and this 
excess is always alkaline, because special care is taken to neutralize all 
the fat. ORGANS OF PROTECTION. 
234 
cially if it is warm, is absorbed to a certain extent 
by the outer cells of the epidermis, so that they swells 
a little and become softer than before. The epider- 
mis thus becomes less elastic and less tenacious. 
If it is suddenly exposed to the cold while in this 
condition, the outer layer contracts and tears apart, 
in some places making cracks, which often extend 
down to the derma, and give rise to considerable 
suffering. Then fatty matter (grease, vaseline, etc.) 
has to be supplied to take the place of the natural 
secretion that has been so unthinkingly removed. 
To keep the skin of the face and hands smooth and 
pliable, therefore, soap should be used sparingly,* 
and they should be thoroughly dried after wash- 
ing. 
292. Care of the Scalp.—The scalp should also be 
kept clean. The epidermis is shed constantly in 
this region, as well as in other parts of the body, 
and, together with the dried sebaceous secretion, 
causes what is known as “ dandruff.” f The hair 
should be dressed with a brush that is not stiff 
enough to scratch the scalp, and the comb should 
be used only to part the hair and disentangle it, 
never to relieve itching. Constant scratching of 
the scalp increases the trouble it is designed to re- 
lieve, and makes it rough and inflamed, just as the 
same treatment will affect the back of the hand or 
the cheeks. It is well to wash the scalp thoroughly 
with cold water at least once a week, drying the 
* The highly-scented toilet-soaps are often made of rancid fat, and 
injure the skin. The best soap for ordinary use is the white Castile 
soap, of Spanish or Italian manufacture, which is made of sweet olive- 
oil and not perfumed. 
f Extreme degrees of dandruff are the result of a disease of the 
scalp, and are often difficult to cure. FUNCTIONS OF THE SKIN.—HYGIENE. 
235 
hair before going- out-of-doors. The hair of girls 
should never be cut, if it is possible to avoid it, as 
it is the universal testimony that it never grows as 
long after cutting as if it is left alone. 
293. Care of the Nails.—The finger-nails should 
be carefully trimmed,* but never cut close to the 
flesh. If they are cut too short, not only is the deli- 
cacy of touch affected, but the ends of the fingers 
will become club-shaped and ugly. The flesh about 
the roots and sides of the nails should not be allowed 
to adhere to them, as it is pulled along and stretched 
as the nail grows, and produces “ hang-nails.” The 
white spots which often appear on the nails are 
caused by slight blows on the root of the nail dur- 
ing its formation, and therefore are most common 
in children and in persons whose occupation exposes 
their hands to such violence. They are of no spe- 
cial importance. 
294. Clothing.—The object of clothing is to main- 
tain an equable temperature at the surface of the 
body. For this purpose the best material to be 
worn next the skin is a poor conductor of heat. 
Woolen material, from its porous texture, conducts 
heat very poorly, and flannel should therefore al- 
ways be worn next the body, summer and winter. 
No other material can be compared with it for pro- 
tecting the surface against sudden changes of tem- 
perature. Linen, on the other hand, is such a good 
conductor of heat, that its use next the skin is 
absolutely dangerous. Cotton is intermediate be- 
tween the two. As for the outside clothing, that 
* It is better to soften the nails slightly in warm water before cut- 
ting ; otherwise they will often split or break at the edge, especially 
in cold weather. 236 
ORGANS OF PROTECTION. 
may be safely left to be decided by the comfort 
and taste of every individual. 
The clothing that has been worn during the day 
should be entirely removed at night on going to 
bed. The under-clothing, which has been for so 
many hours in contact with the surface of the skin, 
is more or less loaded with the matters cast off by 
it, and, if it is not changed daily, should at least 
be thoroughly aired during the night. 
A shoe that can not be worn continuously dur- 
ing the waking hours from the time it is first put 
on, should not be worn at all. The habit of “ break- 
ing-in” new shoes inevitablv results in distortion 
of the feet and the development of corns. High 
heels are also bad, because the weight of the body 
drives the toes down into the narrow end of the 
shoe, and causes the painful and unnecessary affec- 
tion known as “ in-growing ” nails. 
Always wear, therefore, a good non-conductor of heat 
next the skin. 
Never wear any article of dress that pinches, for 
it will inevitably result in distortion or disease, or 
both, especially in the young, whose bones are yield- 
ing and whose organs are not fully formed, and need 
perfect freedom for their healthy development. PART VI. 
ORGANS OF PERCEPTION 
CHAPTER I. 
TOUCH—TASTE—SMELL. 
295. Structure of the Papillae. — The sense of 
touch has its seat in the papillae of the skin. The 
nerves, on entering the papillae, end in certain oval- 
shaped bulbs, which are very small, and are com- 
posed of connective tissue, quite firm in texture, but 
containing a soft material at the center. The nerve, 
on entering this bulb, loses its medullary substance 
(or myelin), and only the axis-cylinder is continued 
into the center. The papillae do not all contain 
such bulbs or corpuscles, but, as they are found 
in the greatest numbers in places where the sensi- 
bility is most acute, it is reasonable to suppose that 
their function is intimately connected with the sense 
of touch. 
296. The Sense of Touch.—By this sense we 
gain our knowledge of hardness and softness, heat 
and cold, roughness and smoothness. The sensi- 
tiveness of the skin, as every one knows, varies very 
much in different parts of the body, and attempts 
have been made to invent some means of measuring 
accurately the perfection of this sense. The most 238 
ORGANS OF PERCEPTION. 
usual method is to apply the points of a pair of 
compasses to various spots on the surface of the 
body, and see at what distance apart the two points 
can be perfectly perceived to be two and not one. 
At the tips of the fingers they can be separately 
distinguished when only one eighteenth of an inch 
apart, while at the small of the back they must be 
separated to a distance of nearly two inches before 
they will cease to seem one point. Between these 
extremes there are many intermediate grades of 
sensation.* 
297. Deception by the Senses.—It is a remark- 
able fact that the extremes of any kind of sensation 
can not readily be distinguished from each other. 
A piece of iron at a white-heat and a frozen solu- 
tion at 70° below zero will produce much the same 
sensation in the part touching them. But it is not 
so familiar a fact that, after all, the conscious sense 
really lies, not in the termination of the nerve, but 
in the nerve-center which receives the impulse from 
it, and that, if this be out of order, the sense may be 
deceptive. This fact of our liability to be deceived 
by our senses applies to all of them—the sense of 
touch as well as to others. A single illustration 
will suffice. It might seem as if any person would 
be able to determine by his feelings whether he 
were hot or cold, and yet it is well known to physi- 
cians that, in the chill of fever and ague, when the 
sufferer, with blue lips and chattering teeth, wants 
* The most delicately sensitive part is the tip of the tongue, where 
the two points are distinguished when only one thirtieth of an inch 
apart. As every one knows, a fine hair, which can not be felt by the 
finger, or only with the greatest difficulty and uncertainty, is clearly 
perceived by the tongue. TO UCH- TASTE—SMELL. 
239 
to be covered deep with blankets, his temperature 
by the thermometer is much higher than in health, 
often running up to io6° Fahr.'* 
298. The Special Senses.—The special senses are 
all modifications of the sense of touch, and were 
probably developed out of it. They differ, how- 
ever, from it, and from one another, in the fact that 
in each a special kind of sensation is roused in re- 
sponse to whatever form of stimulus. Any stimu- 
lus to the retina of the eye, for example, produces 
only the sensation of light—no matter whether it be 
light, or a blow, or an electric current—and so with 
the other special senses (excepting that of taste, as 
hereafter mentioned). In the eye and the ear, the 
apparatus for the special appreciation of stimuli 
forms a highly complicated and delicate mechan- 
ism. In the description of these special senses, we 
shall begin with the one which is least removed 
from the sense of touch, and end with the one in 
which sense-perception is the most highly devel- 
oped. 
299. The Tongue. — The sense of taste differs 
less from ordinary sensibility than any of the other 
senses. It is located chiefly in the tongue, but it 
has been found, by careful experiments, that we 
can perceive the flavor of substances also with the 
soft palate and a small portion of the throat. The 
tongue is a muscular organ of great mobility, and is 
supplied with three nerves from the brain. One of 
* An easy way to satisfy one’s self of the deceptive nature of our 
sensations, and of the fact that they must often be corrected by the 
judgment, is this : Put one hand into cold water, and the other into 
warm ; take them out quickly, and plunge them both into water a little 
cooler than the warm water just used ; it will be found that this water 
will seem cold to one hand and warm to the other. 240 
ORGANS OF PERCEPTION. 
these nerves presides over its motions, while the 
other two are sensitive nerves, one of which is dis- 
tributed to the anterior two thirds of the surface of 
the organ, and the other to the posterior portion 
(Fig. 65). The exact method in which these nerves 
terminate is not known, but the surface of the tongue 
Fig. 65.—Diagram showing the distribution of the nerves of taste in the 
tongue. 
is covered with small papillse, which can be easily 
seen with the naked eye, and the delicate extremi- 
ties of the nerves are known to terminate in these 
papillae. It is well known that no substance can be 
perceived by the taste unless it is soluble, and this 
renders it almost certain that the matter tasted 
comes into actual contact with the end of the 
nerve. 
300. The Sense of Taste.—The nerves of taste, 
in distinction from most nerves of special sense, 
also convey sensation like the nerves of general 
sensibility. This fact makes it a little difficult to 
distinguish between things felt by the tongue and 
things tasted. It is considered by many that there 
are in all only four modifications of the sense of taste, 
viz., sweetness; sourness, saltness, and bitterness. To TO UCH— TASTE—SMELL. 
241 
these qualities, or savors, others add such savors 
as alkaline, styptic, etc., which are compound sen- 
sations, and it is, to say the least, very doubtful 
whether they should be classed as distinct savors. 
Qualities which are really the result of feeling, and 
not of taste, although perceived by the tongue and 
palate, are pungency, starchiness, piquancy, oiliness, etc. 
Another source of error in estimating savors lies in 
the fact that there is a communication between the 
nose and mouth through the throat. It is some- 
times very hard to distinguish between what we 
perceive by the sense of smell and what we taste. 
This is in some degree the case with liquids which 
have an aroma or bouquet, but it may be shown that 
the aroma is perceived entirely by the sense of smell, 
by closing the nostrils while tasting the aromatic 
substance. It will then be found that the aroma 
disappears, although the communication between 
the nose and throat still remains open. The reason 
for this will be explained under the section describ- 
ing the sense of smell. 
301. Peculiarities of the Sense of Taste.—It has 
been stated that the front and back part of the 
tongue are supplied by different nerves. This state 
of things gives rise to a curious phenomenon, viz., 
that certain substances have a decidedly different 
taste when placed on one part of the tongue from 
what they have on the other. A few examples of 
this will suffice : 
If potassium chloride be put upon the anterior por- 
tion of the tongue, it tastes saltish, but on the poste- 
rior, szveetish. Sodium sulphate, on the anterior portion, 
is salt, on the posterior, bitter. Alum, on the anterior 
surface, tastes acid and styptic, while on the posterior, ORGANS OF PERCEPTION. 
242 
it has a decidedly sweetish taste, with no acid qual- 
ity whatever. 
The sense of taste persists for a short time after 
the substance tasted is removed. This is probably 
because the portion of the substance which pene- 
trated the mucous membrane and affected the nerve 
has not all been taken up and carried away by the 
circulation. For this reason, it is impossible to ap- 
preciate the true savor of different substances by 
tasting them in rapid succession. The impression 
made by the first should be allowed to disappear, 
and only remain in the memory, before the sec- 
ond is tasted. This only applies to delicate flavors. 
Where the flavors are coarse and pronounced, the 
slight masking of one by the other often inter- 
feres very little with a correct judgment of their 
character. 
The flavor of any substance is perceived in ex- 
act proportion to the amount of surface affected by 
it. So we see connoisseurs in wine smacking their 
lips and pressing their tongues against the roof of 
the mouth, the better to appreciate the flavor, by 
spreading the liquid over a larger surface. The 
use of this sense in the detection of impure and un- 
wholesome food has already been referred to. In 
addition to this function, it affords us great physical 
pleasure, although it is generally thought to be of 
a low order. 
The sense of taste, like that of touch, requires 
actual contact with the substances tasted, and can 
give us no knowledge respecting substances at a 
distance from our bodies. We now come to a sense 
which is a step higher in the scale, for it gives us 
knowledge of substances at a distance, and it does TO UCH— TASTE—SMELL. 
243 
this by means of material emanations which often 
can not be detected in any other way. 
302. The Sense of Smell.—The sense of smell 
resides in the mucous membrane lining the upper 
portion of the cavity of the nose. This portion of 
membrane is supplied by the olfactory nerve, which 
does not convey ordinary sensation, as do the nerves 
of taste, but carries to the brain only the special 
sensation of smell. The nerve is distributed to the 
upper third of the nasal passages, and the rest of 
the interior of the nose is supplied by nerves of 
ordinary sensation (Fig. 66). 
The amount of any substance required to affect 
the sense of smell is inconceivably minute. There 
Fig. 66.—The interior of the left nasal passage. The fan-like expansion of 
nervous fibers is the olfactory nerve. The other nerves shown are nerves 
of ordinary sensation. 
is no chemical or physical means known by which 
it can be detected in many cases. A grain of musk 
will perfume a room for months, and lose nothing 
apparently in weight ORGANS OF PERCEPTION. 
244 
In order to affect the sense of smell, the odorous 
air must be drawn through the nose. If the air 
in the nasal passages remains stationary, we smell 
nothing. This is the reason why closing the nostrils 
prevents our appreciating aromatic substances in the 
mouth. For this reason, also, we sniff at whatever 
has a delicate or faint odor, and, by increasing the 
rapidity of the air-current through the nose, we add 
to our appreciation of the odor.* This is very no- 
ticeable in the lower animals. 
It is necessary to distinguish between substances 
which really affect the sense of smell and those 
which merely irritate the mucous membrane. Many 
substances affect both senses—that of smell and that 
of general sensibility. Pepper, for instance, has a 
clearly distinguishable and peculiar odor of its own, 
which is appreciated by the olfactory nerve, and it 
also irritates the nerves of general sensibility. Am- 
monia, if pure, is merely an irritant, and has no 
proper odor of its own. 
303. Relative Acuteness of the Sense of Smell.— 
The sense of smell among civilized persons is not 
educated, and is rather defective. Among savages 
it is much more acute. Humboldt states that cer- 
tain South American Indians can detect the ap- 
proach of a stranger, in a dark night, by the sense 
of smell, and will also tell whether he is a white 
man, an Indian, or a negro. But the lower animals 
far surpass man in this as well as in most other 
senses. The keenness of the dog’s scent is pro- 
* The distribution of the olfactory nerve in the upper part of the 
nose also makes it necessary to sniff at faint odors, for otherwise the 
air containing them might pass through the lower passages of the nose 
into the throat, without reaching the nerve of smell. TOUCH— TASTE—SMELL. 
245 
verbial, and he depends much more upon his sense 
of smell, for recognition of his master, than on his 
sense of sight. 
The sense of smell, like the sense of taste, acts 
as a sentinel to guard against the introduction of 
improper food into our stomachs. It also warns 
us of impurities in the air. After long exposure, 
however, to a particular odor, the sense appears to 
become blunted, and that even when the odor is a 
peculiarly disagreeable one. It seems as if, when 
its warnings came to be disregarded, it ceased to 
give any more. 
The sense of smell appreciates a great number 
of distinct odors., and from delicate and fragrant 
ones we receive a great deal of pleasure. This 
sense, undoubtedly, occupies a higher plane than 
the sense of taste, and a delight in pleasant per- 
fumes marks a higher sense of aesthetic gratification 
than a devotion to the pleasures of the table. CHAPTER II. 
HEARING. 
304. The Sense of Hearing.—As we ascend in 
the scale, we come to a sense which does not in- 
form us of what is taking place in the world out- 
side of us, by actual contact with matter, like the 
senses of touch and taste; nor by contact with 
emanations from matter, like the sense of smell; 
but impressions are produced upon it by means of 
motion in the atmosphere which surrounds us. 
This is the sense of hearing. Every movement of 
every form of matter gives rise to waves or vibra- 
tions in the air, which lies in contact with the mov- 
ing substance. These atmospheric waves are re- 
ceived, and the impression made by them is trans- 
mitted to the brain by a special apparatus. 
305. The External Ear.—The ear (Fig. 67) is 
usually described by anatomists as consisting of 
three divisions—the external ear, the middle ear, and 
the internal ear. The appearance of the external 
ear is familiar to all. It has a somewhat shell-like 
form, has numerous ridges and hollows, and is com- 
posed principally of cartilage covered with skin. 
This external ear serves to collect the waves of 
sound, and direct them toward the internal parts. 
In animals this organ is very movable, and, during HEARING. 
247 
their waking hours, is generally in motion, to catch 
sound from various directions. In the human be- 
Fig. 67.—Section of the ear, showing the relative positions of the external, 
middle, and internal ear. 
ing there are three small muscles attached to the 
external ear—one behind, one above, and one in 
front These muscles, however, are practically use- 
less, and very few persons have any voluntary con- 
trol over them. Those who do, can cause the mus- 
cle in the rear to contract, and move the ear slightly 
backward, but the motion is limited, and answers 
no purpose. 
306. The Middle Ear.—From the external ear a 
canal passes directly inward, toward the interior of 
the skull* for a distance of about an inch and a 
quarter. At its inner extremity it is closed by a 
thin membrane, called the membrane of the tympa- 
num, or the drum of the ear; and on the other side 
of this membrane is a small cavity in the bone, about 248 
ORGANS OF PERCEPTION. 
a third of an inch long, a quarter of an inch in height, 
and a sixth of an inch wide, called the tympanum,* or 
middle ear. The membrane of the tympanum is 
stretched like the head of a drum, and answers some- 
what the same purpose. Upon this membrane the 
waves of air strike, causing it to vibrate ; and this 
vibration of the membrane is the first step toward 
bringing the air-waves, or the impulse given by them, 
into contact with the nerve of hearing. And here 
we remark that, in order for the vibration of a mem- 
brane to be perfect, the air on both sides of it must 
be of the same degree of density during the vibra- 
tion. In the common drum this is provided for by 
having a hole in the side, to allow free passage for 
the air in and out. In the cavity of the middle ear 
it is provided for by a short tube, called the Eusta- 
chian f tube, leading into the throat. This tube is 
about an inch and a half or two inches long, and, 
for perfect hearing, it is necessary that the air 
should pass in and out through it with freedom. 
307. The Bones of the Ear.—In the cavity of the 
middle ear is a chain of minute bones, three in number, 
which altogether only weigh a few grains. One of 
them is attached to the membrane of the tympanum, 
another is attached to another membrane stretched 
in drum-like form across a small hole on the oppo- 
site side of the middle ear, and the third unites the 
other two. These small bores have very minute 
muscles attached to them in such a way that by their 
contraction or relaxation the bones are made to as- 
sume slightly different positions, and the membranes 
* Tyiripanum, a Latin word meaning drum. 
f Eusta'chian, from Bartolomeo Eustachi, a celebrated Italian anat- 
omist (died 1574), who first described it. HEARING. 
249 
to which they are attached are made more or less 
tense, and therefore more or less sensitive to sounds. 
It is probable that these muscles are somewhat un- 
der the control of the will, and that some of the 
effort of which we are conscious when we strain our 
attention to detect a faint sound, is due to their 
active contraction. 
308. The Internal Ear.—The second membrane 
above spoken of, which is smaller than the mem- 
brane of the tympanum, closes the passage between 
the middle and internal ears. The internal ear or 
labyrinth is exceedingly complicated, and the func- 
tions of its parts are not yet well understood. The 
difficulties of investigation are immense, partly on 
account of the minuteness of the organs and partly 
because they are situated so deeply in the bones of 
the skull and are so near the brain. It is sufficient 
to say that the internal ear is made up of many 
winding channels and spiral tubes, which go by the 
names of the cochlea, the semicircular canals, and a 
cavity called the vestibule, with which the others 
communicate. All these passages are filled with a 
watery fluid, and on their walls and through their 
interiors are distributed the filaments* of the nerve 
of hearing, the auditory nerve. As has been said, the 
cavity of the vestibule is separated from that of the 
middle ear by a thin membrane, to which one of 
the bones of the middle ear is attached. Thus, any 
vibration or impulse imparted to this membrane 
produces a corresponding pressure on the nerve of 
hearing, through the medium of the watery fluid 
which fills all parts of the internal ear. 
309. Recapitulation.—Thus the air-waves enter- 
* Filaments, small, delicate, thread-like fibers. ORGANS OF PERCEPTION. 
2 50 
mg the external ear strike upon the membrane of 
the tympanum and put it in vibration. These vi- 
brations are communicated through the chain of 
bones to the inner membrane, which is also made 
to vibrate. These vibrations, again, are communi- 
cated to the watery contents of the internal ear, 
and they in turn press directly upon the extremities 
of the auditory nerve, which conveys the impulse 
to the brain. And in this way we hear sounds. 
310. Different Qualities of Sound.—When we 
hear sounds, we distinguish many different quali- 
ties in them, such as pitch, quality, titnbre, degree, 
etc. These differences mainly depend upon the 
different length, rapidity, height, and character of 
the air-waves. They are perceived, in a greater or 
less degree, by every person, but the ease and ac- 
curacy with which they are appreciated may be in- 
creased by education. The appreciation of musical 
sounds, for instance, may be immensely increased 
by practice and proper training. 
311. Determination of the Source of Sound.— 
Besides the perception of the foregoing differences 
in sounds, which is partly the result of natural en- 
dowment and partly that of training, there is an- 
other fact with regard to sound which has given 
rise to considerable discussion. It is the power we 
have of determining with more or less accuracy the 
locality from which a sound comes. Some physi- 
ologists have supposed that, as the semicircular ca- 
nals, three in number, are always placed at different 
angles, they serve in some way, not easily explained, 
to indicate to us the direction from which the air- 
waves come.* This view has been supported by 
* It has been lately suggested that the semicircular canals have HEARING. 
251 
arguments of some plausibility, but it is now the 
accepted view that our knowledge of the direction 
and distance of the source of any sound is the re- 
sult of past experience. We judge partly by the 
loudness of a familiar noise, partly by the greater 
impression on one ear than on the other, partly by 
the difference in the sound when we turn the head 
a little one way or the other, the direction of the 
wind, and a hundred other influences, which have 
become a part of our experience. If we can not, 
for any reason, use enough of these methods, we 
find ourselves unable to locate even a loud and dis- 
tinct sound ; e. g., it is very difficult to tell in what 
part of a closed room to look for a chirping cricket. 
312. Ventriloquism.—The art of ventriloquism de- 
pends upon an adroit use of these methods in such 
a way as to deceive. The ventriloquist slyly robs 
us of all the means which generally serve us to 
detect the origin of a sound. He speaks without 
moving his lips ; he modulates his voice so that it 
appears to come from a distance, on account of its 
faintness; he calls the attention of the spectator, 
either by word or by gesture, to the point from 
which he wishes him to expect the sound, and 
makes clever use of the slight shades in timbre and 
pitch, which all of us can distinguish, but which it 
requires great skill and practice to reproduce as 
something to do with the sense of direction, and with the preservation 
of the bodily equilibrium. It has been found that, when they are cut in 
a pigeon, the bird sprawls about and seems incapable of co-ordinating 
its movements. There is a disease of these organs, called Meniere’s 
disease, from the man who first described it, in which giddiness, as well 
as deafness, is a prominent symptom. It is probable that the frequent 
attacks of vertigo, with increasing deafness, from which Dean Swift 
suffered, were caused by this disease. ORGANS OF PERCEPTION. 
252 
professors of this art are able to. The common 
idea that a man’s voice can actually be projected 
or thrown into a spot twenty feet from his larynx 
is the idea of pure ignorance, and, as soon as one 
understands the mechanism of the voice, is seen to 
be as impossible as for any one to see through a 
solid stone wall, a thick envelope, a book-cover, or 
anything else through which no light can pass. 
313. Care of the Ear.—The ear is, in almost ail 
its parts, a very delicate organ, but, excepting the 
external ear, it is so deeply set in bone that it is 
not very liable to injury ; and yet neglect of the 
organ or ignorant tampering with it may result in 
permanent and irreparable harm. The tube leading 
inward from the external ear, called the external 
auditory canal, is sometimes entered by insects. Its 
walls are moistened by a peculiar secretion, called 
“ wax,” produced by small glands just beneath the 
skin which lines it. This wax is somewhat sticky, 
and is intensely bitter, and, together with certain 
short hairs near the outlet of the canal, serves to 
protect the membrane of the tympanum from the 
inroads of insects.* The wax has sometimes a 
tendency to accumulate and interfere with the 
hearing; and some persons are in the habit of 
cleaning their ears with ear-scoops. This is an 
exceedingly dangerous practice, and can not be 
too severely condemned. The ear is a delicate or- 
gan, and must be treated delicately by a person 
who thoroughly understands its anatomy. 
314. Danger of Colds in the Head.—The dan- 
* Insects can sometimes be coaxed out of the ear by holding a light 
in front of, and quite near, the external opening. They are attracted 
by the light, as moths are, and turn round and crawl toward it. HEARING. 
253 
ger of injury to the hearing apparatus through the 
Eustachian tube is principally from inflammation. 
Colds in the head almost always affect the hearing 
in some degree, on account of the swelling of the 
membrane around the mouth of the tube. But the 
inflammation may not stop at this point. It some- 
times travels along the tube to the middle ear, and 
when the exceedingly delicate mucous membrane of 
the middle ear becomes affected, there is usually 
more or less permanent impairment of the sense of 
hearing. The little chain of bones becomes stiffened 
by the disease, just as an elbow or knee does after 
an attack of rheumatism, and so they conduct the 
vibrations of the membrane of the tympanum with 
less force and accuracy. On the slightest indication, 
therefore, of inflammation of the Eustachian tube, 
as indicated by unusual dullness of hearing, during 
an acute catarrh of the nose or throat, a physician 
should be consulted. The process just described 
gives rise, in the climate of New York, to about 
two thirds of all the cases of deafness. CHAPTER III. 
SIGHT. 
315. The Sense of Sight.—We now come to the 
highest and most perfect of all the senses, that of sight. 
The four senses previously considered all depend 
on material contact, in a greater or less degree, for 
their appreciation of the external world. Even the 
last sense considered, that of hearing, depends on 
contact with waves in the air, which is a form of 
matter, although attenuated. But we now have to 
do with an organ which perceives external objects 
through the intervention of light, and light is some- 
thing which can not be felt or weighed, or detected 
in any other way than by sight. There have been 
many theories regarding the nature of light, but 
the one most in favor at the present day is the wave 
theory, or undulatory theory, so called. 
316. The Nature of Light.—According to this 
theory, the universe is pervaded by an exceedingly 
subtile form of matter called the ether, and light 
consists of waves propagated through this ether 
with tremendous rapidity. The average number 
of vibrations in a second is estimated to be over 
500,000,000,000,000, and they travel at the rate of 
about 187,000 miles per second. The wave theory 
of light is only a theory, and the existence of the SIGHT. 
255 
extremely attenuated form of matter called ether, 
which can neither be weighed, seen, heard, nor felt, 
but only postulated from certain phenomena sup- 
posed to depend upon it, is only inferred ; but still 
this theory explains almost all the phenomena of 
light, and, until some better one is suggested, must 
be retained as a working hypothesis. 
From these facts, we can judge of the extraor- 
dinary delicacy of the eye as an organ of sense. 
Here is a stimulus, of unknown origin, which can 
traverse the widest regions of space, which enables 
us to appreciate the existence and form and even 
the structure of bodies which are billions of miles 
away from us, and gives us more knowledge of the 
external world, perhaps, than we obtain through all 
our other senses together, and yet its real nature is 
as hidden and mysterious and impalpable as the na- 
ture of our consciousness. Let us now examine the 
structure of the organ which perceives this strange 
stimulus and enables it to affect our brain. 
317. Situation of the Eye.—The eye is situated 
in a cavity called the orbit, surrounded by bone ex- 
cepting in front, and padded all about with fatty 
and muscular tissues, so that, although it is pro- 
tected from injury by an unyielding bony case, it 
still reposes on a soft and elastic bed. 
318. Structure of the Eyeball. — The eyeball 
(Fig. 68) is nearly spherical, and about an inch in 
diameter. It is formed of three membranes, ar- 
ranged concentrically one within the other, and the 
interior is filled with certain structures necessary to 
vision. The outer membrane is called the sclerotic* 
* Sclerot'ic, from the Greek crK\rip6s, hard, because it is the hardest 
and toughest coat of the eye. 256 
ORGANS OF PERCEPTION. 
coat, and in front, where it is visible, constitutes 
what is commonly known as the white of the eye. 
Fig. 68.—Horizontal section of the right eye, showing the relative position 
of its parts. 
It is composed of white, fibrous tissue, and is ex- 
ceedingly strong, tough, and elastic. It surrounds 
the whole eyeball, excepting in front, where a trans- 
parent membrane, about of an inch thick, is set 
into it like a watch-glass in the case. The front of 
the eye must of course be transparent for the ad- 
mission of light. This portion of the eye is called 
the cornea.* 
* Cor'nea, from the Latin cor'till, a horn, because of its resemblance 
to transparent horn. SIGHT. 
257 
Just inside the sclerotic coat is another coat, 
called the choroid,* which covers the whole interior 
of the eye, excepting that portion bounded by the 
cornea. This coat is very plentifully supplied with 
blood-vessels, and with immense numbers of minute 
cells, filled with coloring-matter, so that it appears1 
of a dark-brown or chocolate color, and in some 
persons almost black. Inside this choroid coat, 
again, is the retina,f which is an exceedingly deli- 
cate and complicated membrane made up of nerv- 
ous tissue, and upon which the impressions of light 
are received. The retina is spread over about two 
thirds of the inner surface of the eyeball, not reach- 
ing quite as far forward as the sclerotic and choroid 
coats. 
319. The Internal Parts of the Eye.—The mem- 
branes above mentioned form, so to speak, the in- 
casement or shell of the eyeball. The bulk of the 
interior of the eye is formed by the vitreous humor\ 
This is a soft, semi-fluid, transparent, jelly-like body,* 
* Choroid, from the Greek x<V‘0,'> father, because, being dark-col- 
ored, it resembles leather in appearance. 
f Ret'ina, a Latin word, meaning in that language just what it 
means in English. It is derived from re te, a net, on account of its 
mesh-like appearance. 
\ Vit'reous, from the Latin vit 'reus, glassy. 
# The vitreous humor contains, even in healthy eyes, minute bodies, 
which can not be detected from the outside, but which can be seen, 
greatly magnified, by the person himself. They are called “ musciz 
volitantes" (literally, flitting flies), and look like small strings of bright 
beads, or little transparent spheres or fibers, which move when the eye 
is moved, and, when the eye is held perfectly still, seem to sink slowly. 
They really float up toward the top, but appear to go down, their di- 
rection being reversed by the optical apparatus of the eye. These little 
objects are seen most vividly against a bright surface, like the sky, or a 
white wall, and when perceived for the first time are apt to frighten ORGANS OF PERCEPTION. 
258 
which fills the ball of the eye, with the exception 
of a small part, about one sixth of the mass, in front, 
which contains the crystalline lens and the parts be- 
tween the lens and the cornea. This vitreous hu- 
mor is surrounded by a very delicate membrane, 
also transparent, which lies in immediate contact 
with the whole extent of the retina. Just where 
this membrane passes in front of the vitreous hu- 
mor, and just behind the cornea, it splits in two 
layers, and between these layers is suspended and 
held in place the crystalline lens. This lens is a 
double-convex one, with the posterior curvature a 
little greater than the anterior, is about one third of 
an inch in diameter from side to side and a quarter 
of an inch thick at its middle. It is, of course, per- 
fectly transparent, and acts precisely as a double- 
convex lens acts in any optical instrument. Just in 
front of the lens is a curtain, with a hole in its cen- 
ter, which serves to regulate the admission of light 
to the interior of the eye. This curtain is called 
the i'ris* and it contains muscular fibers, to which 
it owes its power of contraction, and pigment-cells, 
to which it owes its color, varying in different per- 
sons. The hollow space between the cornea in 
front and the crystalline lens behind is filled by a 
fluid called the aqueous humor,\ composed almost 
entirely of water, with a little salt. 
320. Uses of the Two Outer Coats of the Eye. 
—The sclerotic coat serves, by its toughness and 
people. They exist, however, in every eye, and are perfectly harm- 
less. 
*'*Ipis, a Greek word, meaning the rainbow, so called on account of 
the variety of colors it presents in different eyes. 
-j- A'queous, from the Latin a'queus, watery, because it consists al- 
most entirely of water. SIGHT. 
259 
elasticity, to give shape to the organ, and protect 
the parts within. The cornea in front answers the 
same purpose, and is transparent, in order to allow 
the passage of light. The 
choroid coat serves as a 
nest for the blood-ves- 
sels which nourish the 
retina, and also, by its 
dark color, prevents the 
rays of light, which have 
once passed through the 
retina, from passing back 
again, and so confusing 
the sight. When the nght 
which enters the eye is 
so intense that it can not 
be absorbed by the cho- 
roid, it is thus reflected 
through the retina, and 
our sight is not clear, as 
we have a double im- 
pression, coming from 
two directions, and the 
rays conflict with each 
other. We call this “ be- 
ing dazzled.” In albinos, 
the coloring-matter of 
the choroid is absent, 
and such persons always 
are troubled with dimness and confusion of sight.* 
Fig. 69.—Vertical section of the ret- 
ina, highly magnified. At the 
upper part of the cut are the rods 
and cones, while below are several 
distinct layers of nerve-cells. 
* Albinos not only can not, see well, because they are dazzled by 
the light, but their eyes have a constant vibratory motion from side to 
side, like the pendulum of a clock. This peculiar affection is known 
to physicians as nystagmus. 260 
ORGANS OF PERCEPTION. 
321. The Retina.—The retina is formed by the 
expansion of the optic nerve, which enters the eye 
behind and spreads out over the interior. It is ex- 
ceedingly complicated in its structure (Fig. 69), no 
less than eight distinct layers being found in its 
thickness, although the whole taken together is very 
thin and delicate. The outermost layer is made 
of innumerable minute cylinders of nervous matter 
of different shapes and sizes, packed together side 
by side like the seeds of a sunflower. These are 
called the rods and cones of the retina. Inside of these 
are other layers of tubes, fibers, cells, and granular 
matter, all of which, doubtless, have their part to 
play, but the particular function of which is not yet 
known. This arrangement of the nerve substance is 
necessary to the sense of sight, for, singularly enough, 
the spot where the optic nerve enters the eyeball is 
entirely blind. This nerve can convey the impres- 
sion of sight to the brain as it receives it from the 
special sense-organ the retina ; but, if light falls di- 
rectly upon the optic nerve itself, no sensation is 
produced. This curious and interesting fact can be 
easily demonstrated. 
Make a round black spot and a black cross upon 
a white card, three inches apart (Fig. 70). Now 
Fig. 70.—Diagram to demonstrate the existence of the blind spot. 
hold the card in front, at a distance of about a foot 
from the eyes, close the left eye, and look at the 
cross with the right one. Both the cross and the SIGHT\ 
261 
black spot will be seen distinctly. Now move the 
card slowly toward you, still keeping the right eye 
fixed upon the cross. At a certain point the round 
spot will disappear, but, as the card continues to 
approach the eye, it will reappear within the field 
of vision. At the point of disappearance, its image 
falls upon the optic nerve just where it enters the 
eye (Fig. 71). Now, if this blind spot were just in 
the axis of the eye, we should be badly off, for it is 
Circular image inside the 
nerve (blind spot). 
Image on the nerve 
(blind spot). 
Image outside the 
nerve (blind spot). 
Fig. 71.—Diagram illustrating the blind spot. It represents a horizontal 
section of the right eye, the axis of the eye in every case being turned to- 
ward the cross. 
evident that we should be unable to see anything 
we looked directly at. But the point of entrance 
of the optic nerve is toward the inner side of the 
eyeball, and consequently we are not incommoded 
at all by this small spot, which is insensible to light. 
322. Use of the Crystalline Lens.—The interior 
of the eyeball is, therefore, like the interior of a 
camera obscura. It forms a dark chamber, lined with 
a dark membrane, to absorb superfluous light, and 
with a small opening in front to admit light. Just 
behind this opening is the lens. 
If light came directly into the eye, and fell upon 
the retina, without being brought to a focus, our 
brains would appreciate the existence of the light, 
but would not get clear ideas of the appearance of 
objects. Everything would be dim and confused. ORGANS OF PERCEPTION. 
Something of this may be seen in a camera obscura, 
if the lens be removed. The rays of light, as they 
enter the camera, still form an image of outside ob- 
jects, but it is a dull, indistinct, and obscure one. 
With the lens, however, the picture is bright and 
distinct in all its details. The reasons for this are 
too long to be stated here, and will be found in any 
treatise on optics. Suffice it to say that the func- 
tion of the crystalline lens is to concentrate the rays 
of light as they enter the eye, and bring them to a 
focus on the retina. 
323. The Function of Accommodation. — The 
rays of light being affected by this lens precisely as 
they would be by a glass one, there must be some 
provision made for the varying distance of objects 
from the eye. In the camera, as objects are nearer 
or more distant, we draw out or push in the lens, 
so as to bring it farther from or nearer to the sur- 
face which receives the image. Now, we find that, 
within certain limits, a healthy eye sees objects a 
moderate distance away with just as much distinct- 
ness as those near at hand. Moreover, we are con- 
scious, as we change rapidly from looking at a dis- 
tant object to one close by, of a kind of effort in the 
eye itself. There must be a change of some kind 
there, corresponding to the pulling out or pushing 
in of the lens of the camera. What is the change ? 
There is a short, delicate muscle, called the cili- 
ary muscle, one extremity of which is attached to 
the stout membrane of the sclerotic and cornea at 
their junction, and the other extremity to the cho- 
roid. The muscle is a circular one, reaching all 
around the eyeball, and is only about an eighth of 
an inch broad. Now, the crystalline lens is very SIGHT. 
263 
elastic, and, as has been stated, it lies between two 
layers of a membrane which passes backward and 
surrounds the vitreous humor. Under ordinary 
circumstances, these two layers of membrane, one 
of which is in front of the lens and the other be- 
hind it, are supposed to exercise some pressure on 
it, and render it a little flatter than it would be, if it 
were left to take its own shape, in accordance with 
its elasticity. Now, suppose that we wish to look 
at an object close at hand. . The ciliary muscle con- 
tracts and the membranes surrounding the vitreous 
humor are drawn forward slightly. As a conse- 
quence of this the two layers of membrane, between 
which the lens lies, are somewhat relaxed, and exert 
less pressure on the front and back of the lens. The 
pressure being removed from it, the 
elasticity of the lens makes it assume 
a more convex shape (Fig. 72), and 
consequently brings the rays of light 
to their proper focus. This is sup- 
posed to be the method by which 
the eye accommodates itself to differ- 
ent distances, and its operation is so 
perfect and exact that, within certain 
limits, we can see whatever we wish 
to. Beyond a certain distance, and 
within a certain distance, this accom- 
modation no longer occurs. These 
distances vary with different per- 
sons, and the inner limit is called the limit of dis- 
tinct vision. 
324. The Limit of Distinct Vision.—The limit of 
distinct vision depends on the accommodation of 
the lens above described. As any object is brought 
Fig. 72.—Diagram 
showing how the 
lens changes its 
form for near and 
far sight. 264 
ORGANS OF PERCEPTION\ 
nearer and nearer to the eye, the effort required to 
see it distinctly, or, in other words, the effort at ac- 
commodation, is greater and greater, until at length 
it begins to be accompanied by pain and a peculiar 
sense of fatigue in the eyes. Within this point dis- 
tinct vision is not possible, for the ciliary muscle 
can contract no further. In healthy eyes, this limit 
is usually about six inches from the cornea. 
As objects recede, the rays from them come to 
the eye at a smaller and smaller angle, until, at 
the distance of fifty feet, they are almost parallel; 
that is, they are practically so, as far as the percep- 
tion of the retina is concerned. Beyond this point, 
vision is distinct enough, and no accommodation of 
the lens is required ; but a new difficulty comes in 
to hamper us in our perception of objects. We 
have seen that, however delicate the sense of touch 
may be, it is possible to press two points of a com- 
pass on the skin so near together that we are not 
able by the sense of touch to say whether they are 
two points or one. A similar condition is found to 
exist in the retina. It has been shown by experi- 
ment that, if two objects or two points of any ob- 
ject are so near together that both combined sub- 
tend an angle of less than one minute at the lens, 
the retina can not distinguish them apart. Beyond 
the distance of fifty feet, then, without artificial as- 
sistance, the eye is unable to distinguish objects 
perfectly in their minute details. 
325. The Function of the Iris.—The color of 
the iris is due partly to the blood-vessels which run 
through it, and partly to small pigment-cells. In 
new-born children the iris is always blue, and does 
not take on the color which is to last through life SIGHT. 
265 
for several weeks after birth. The iris performs 
two functions. In the first place, in every lens, the 
whole of which is made of the same substance and 
of the same density throughout, the rays of light 
which pass through and near the center are not 
brought to a focus as soon as those which pass 
through near the circumference. This fact causes 
a blurring of the image (spherical aberration) and 
also a partial decomposition of the light (chromatic 
aberration), so that the image appears colored at 
its edges. In optical instruments these difficulties 
are remedied, partly by constructing the lens of two 
different substances, which counteract each other’s 
defects, and partly by covering the edge of the lens 
and only allowing the light to come through the 
center and the immediately adjacent parts. The 
latter method is the one carried out by the iris. It 
is pierced in the center, forming the pupil of the 
eye, and this pupil is situated immediately in front 
of the center of the lens, so that in this way the 
faults above mentioned are corrected. The iris 
also regulates the admission of light to the eye. 
Too much light irritates the retina, and by reflex 
action the iris contracts. If there be too little light 
the iris is relaxed, and the pupil becomes larger so 
as to admit more. This process has already been 
mentioned at length. 
326. The Retina and Optic Nerve sensitive only 
to Light.—The retina is sensitive to other impulses 
than that of light, but, whatever these impulses 
may be, the sensation of light is the only one con- 
veyed to the brain. If the eyeball be struck or 
pressed, or an electrical current be passed through 
it, we see sparks or flashes of light, and this even 266 
ORGANS OF PERCEPTION. 
when we are in a perfectly dark room. This is due 
to the shock to the retina, from which every stimu- 
lus of whatever kind is transmitted by the optic 
nerve to the brain under the form of light. 
327. Persistence of Impressions on the Retina. 
—When an image is formed on the retina, espe- 
cially if it is a very bright one, the impression re- 
mains a little while after the object that caused it 
has passed by. The consequence of this is that, if 
several objects follow each other in very rapid suc- 
cession, new images are continually formed on the 
retina before those that immediately preceded them 
have had time to fade, and so the eye does not de- 
tect any interval between them. Thus, when we 
look at a swiftly-revolving wheel, we do not see the 
separate spokes, but a continuous, hazy blur; and 
when a live coal is whirled around fast enough be- 
fore the eyes, we do not see the coal in its proper 
shape, but only a luminous circle. In this tempo- 
rary persistence of impressions on the sense of 
sight, it is like all the other senses. 
328. Color-Blindness.—The power of discrimi- 
nating between different colors varies very much in 
different individuals. While some can not only dis- 
tinguish the colors with ease, but can pick out the 
most delicate shades of any particular color with 
unfailing accuracy, others are unable to discrimi- 
nate, for example, between red and green. Such 
persons are called color-blind, and can not see any 
difference between the fruit and the leaves of a 
cherry-tree, excepting by the shape. 
329. Near-Sight and Far-Sight.—In the natural 
and healthy eye the rays of light are brought to 
a focus on the retina, but in some eyes they are SIGHT. 
267 
not. In near-sighted persons the eyeball is usually 
a little too long, and the rays of light, being brought 
to a focus before they reach the retina, cross each 
other, and the image is blurred. In far-sighted 
eyes the eyeball is too short, or the lens is too flat, 
and the rays are not brought to a focus at all, so 
that the effect upon vision is to make everything 
look blurred, as in the former case (Fig. 73). Both 
of these defects can and should be corrected by 
proper glasses, for the constant straining to see, of 
Fig. 73.—Diagram showing the point at which the rays of light are brought 
to a focus in different eyes. 
short-sighted and far-sighted persons who try to get 
along without glasses, eventually injures the sight. 
330. Muscles of the Eyeball.—To the outside of 
the eyeball are attached six muscles, by means of 
which it can be moved in any direction. Four of 
them pass from the four sides of the eyeball straight 
backward to the bone at the rear of the orbit, and 
move the eye up or down, and to the right or left. 
The other muscles are attached, one to the upper 
and the other to the lower surface of the eye-ball, 
their other ends being attached to the bones on the 
inner side of the orbit in such a way that, by their 
contraction, the eyeball is rolled in one direction or 
another. 268 
ORGANS OF PERCEPTION. 
331. The Eyelids and Eyebrows.—This delicate 
organ—the eye—is protected from injury in front 
by a number of accessory parts, viz., the eyelids, eye- 
lashes, and eyebrows. 
The eyelids are composed of thin pieces of car- 
tilage, covered with skin on the outer and lined 
with mucous membrane on the inner side. They 
are movable, and, when open, expose nearly all the 
iris; when shut, they completely cover the eyeball. 
At their margins are several short, stiff hairs—the 
eyelashes—which project outward and downward, 
and serve as an additional protection against the 
entrance of dust and insects. Above the eyes are 
ridges of thick skin, also covered with hairs, and 
called the eyebrows, which turn aside the perspira- 
tion or other fluids which run down the forehead 
toward the eyes. 
332. The Tears.—In order to keep the cornea 
perfectly smooth and transparent, and to preserve 
the softness of the mucous membrane lining the in- 
terior of the lids, which continually sweep over the 
cornea, and if rough would irritate and ruin it, a 
special fluid is provided, called the tears, which are 
continually secreted, and keep those parts constant- 
ly moist. The gland which provides the tears, 
called the lach'rymal gland (Fig. 74), is situated inside 
the orbit, just above and outside of the eyeball, and 
its secretion is poured out on the eye by several 
little openings at the upper part of the upper lid, 
on its inner surface. By the winking of the lids, 
which occurs frequently and is usually involuntary, 
it is spread over the surface of the eye. On the 
edge of the lids, near the inner angle of the eye, 
may be seen two minute openings, one in each lid. SIGHT. 
269 
These are the mouths of two little canals, which 
pass from these points toward the nose, soon unit- 
Fig. 74.—Left eyelids from behind. Above and at the left is the lachrymal 
gland. On the lids are seen what look like strings of beads. They are 
glands that secrete the fatty matter that coats the edges of the lids, and 
ing in one larger canal, which runs downward into 
the nasal cavity. Through these minute canals, the 
superfluous tears run off into the nose. These 
canals are lined with mucous membrane, and, dur- 
ing a cold in the head, the inflammation often closes 
them, and the tears, not finding free passage through 
them, overflow. upon the cheeks. This overflow 
also occurs when from pain or any powerful emo- 
tion the tears are increased in amount so that the 
canals are unable to dispose of the extra supply. 
This phenomenon we call crying or weeping. An 
overflow of tears is guarded against under ordinary 
circumstances by an oily secretion of certain glands 
in the lids, which is discharged just along their 
edges. This secretion keeps the lids from sticking 
together when closed, and also retains the tears, un- 
less their quantity is greater than common. ORGANS OF PERCEPTION. 
333- Care of the Eyes.—It is exceedingly impor- 
tant that proper care should be taken of the eyes. 
They are very delicate, and yet there is hardly an 
organ in the whole body, not even excepting the 
stomach, that is more frequently abused. If any- 
thing be the matter with the eyes—if they' smart, or 
tingle, or itch, or the sight is dim, or blurred, or in- 
distinct—a good oculist should immediately be con- 
sulted. More is known about the eye, probably, 
than about any other organ in the body. The most 
eminent scientists in the world have spent their best 
years in the study of it in health and disease, and 
it can be examined inside and outside thoroughly. 
As a consequence, operators who devote their spe- 
cial attention to this organ generally know what 
they are about, and their advice should be carefully 
and minutely heeded. It will not do for individuals 
to treat their own eyes, and therefore it is unneces- 
sary to say anything about its disorders. With re- 
gard to proper care of the eye, it is almost enough 
to say, Do not do anything to produce a feeling of 
“strain” in the organ. This sensation, as already 
explained, is produced by the effort of accommoda- 
tion, and, as the muscular contraction accompany- 
ing this act compresses the interior of the eye some- 
what, it causes a congestion of the blood-vessels, 
which is usually only temporary, and passes away 
when the cause is removed. If a strain like this, 
however, be often repeated or long continued, it is 
apt to result in permanent injury to the sight, just 
as long-continued congestion of the blood-vessels in 
any other part of the body will impair the working 
of the organ in which it occurs. The same effect is 
produced by reading or using the eyes for fine SIGHT. 
271 
work while stooping or lying, or during the inces- 
sant jarring of a vehicle, especially a railroad-car. 
The eyes should not be rubbed, or pressed, or 
squeezed, or used by a bad light, or in any other 
way treated as if they could bear rough usage.* 
They can not, and, if they are abused, the sight is 
apt to fail in a sudden and alarming manner. 
* It is supposed by many that the eyes are strengthened by being 
opened in cold water when the face is washed. This is not so. On 
the contrary, it is an exceedingly injurious practice, and frequently 
produces little ulcers on the surface of the eye, which, although per- 
haps not dangerous, are very painful, and may prevent the use of the 
affected eye for several days. The eyeball is washed sufficiently by 
the tears. PART VII. 
ORGAN OF SPEECH. 
334- Structure of the Larynx.—In the upper part 
of the neck, in front, is a hard, projecting mass, 
which, in the throats of thin persons, is plainly vis- 
ible, and in every one can be easily felt. This is 
commonly called Adam's apple, and consists of the 
projecting cartilages which form the sides of the 
larynx. This organ is situated at the upper end of 
the trachea, and a cross-section of it is nearly trian- 
gular in shape. It is composed mainly of cartilage, 
and forms a stiff, open, box-like organ, covered on 
the outside with muscles, and on the inside with 
mucous membrane. 
335. The Vocal Chords.—The upper end of the 
larynx is nearly closed by muscular and membra- 
nous tissues, which divide it at this point from the 
throat. But it has a chink-like opening, the glottis, 
previously described, situated at the base of the 
tongue, just behind the epiglottis. This is the es- 
sential organ of voice. All the air which passes 
into or out of the lungs must go through the glot- 
tis. Now, in front, the vocal chords, which form the ORGAN OF SPEECH. 
273 
sides of the glottis, are nearly or quite in contact, 
while the posterior extremities can be separated to 
quite a distance from each other. These posterior 
ends are attached to two small cartilages, which can 
be rotated by certain muscles, so as to separate the 
vocal chords. When certain other muscles contract, 
which*act in an opposite direction, the cartilages are 
rotated inward, and the vocal chords are brought 
nearer together.* Other muscles render the chords 
tighter or looser, according to circumstances (Fig. 
75)- 
336. How the Voice is produced.—Now, when 
High note. 
Medium note. 
Low note. 
Fig. 75.—The vocal chords in different positions. The opening between the 
chords is the glottis. 
the air is forced through the glottis in expiration 
with sufficient rapidity, the vocal chords are thrown 
into vibration, and, vibrations being thus caused in 
the column of air in contact with them, sound is 
produced. The quality of this sound, as well as its 
pitch and tone, depends upon well-known physical 
laws. The farther apart and the more relaxed the 
vocal chords are, the lower will be the sound ; the 
* These cartilages are triangular in shape, and act very much like 
the triangular pieces of metal to which bell-wires are fastened. The 
vocal chord being attached to one corner, and the muscle to another, 
while it rotates about the third angle, it is evident that when one muscle 
contracts the vocal chord will be moved outward, and when another op- 
posing muscle contracts the end of the chord will be moved inward. ORGAN OF SPEECH. 
274 
nearer together and tighter drawn they are, the 
more acute will be the sound. Differences also de- 
pend upon the size of the larynx and trachea, the 
length of the vocal chords, their thickness and 
smoothness, the condition of the throat and parts 
adjacent, etc. 
In this way the sound is made which we call 
voice, and it is modulated into articulate speech 
by the action, separate or combined, of the throat, 
nose, palate, tongue, teeth, and lips. To consider 
how these variations are produced would require 
great space, and be foreign to the purpose of this 
book. It is sufficient to say that the voice is pro- 
duced in the larynx, and articulation performed by 
the parts above that organ. 
337. Abuse of the Larynx.—Abuse of the larynx 
produces bad results, as does abuse of any other or- 
gan of the body. Perhaps the most common form 
of this is the use of the voice, when the vocal chords 
are in an inflamed or congested condition. Over- 
use of the larynx in speaking is apt in many persons 
to bring on congestion of the chords. This causes 
them to swell a little, and the voice loses some of 
its clearness. If rest be not given the organ at 
such a time, the congestion continues, and becomes 
chronic. Then the voice is permanently altered, 
becoming rough and harsh as compared with its 
original quality. Very often a sore-throat extends 
to the glottis, and the mucous membrane which 
covers the vocal chords becomes inflamed. Then 
the usual results of inflammation of a mucous mem- 
brane follow. The chords swell and are covered 
with a thick secretion, like that which is coughed 
up during such an attack. This thickening of the ORGAN OF SPEECH. 
275 
chords affects the voice, and makes it not only- 
harsh but of a lower note than usual, just as in a 
violin the large strings give forth the low notes 
and the smaller ones the high notes. The secretion 
also hinders the vibration of the chords, and some- 
times the voice is reduced to a whisper or even ex- 
tinguished, because the chords are so disabled as 
not to be able to vibrate at all. A curious phenom- 
enon sometimes occurs in such cases, called the 
“ breaking of the voice.” If the mucous secretion 
be very viscid, as it often is, the chords may stick 
together at some point during the act of speaking, 
and the part that vibrates is instantly reduced in 
length to perhaps three quarters of what it was a 
moment before. This has the same effect as the 
shortening of a string of a violin by pressing it 
with the finger. It makes the voice suddenly take 
on a higher note. In the next instant the chords 
become entirely separated, and the former note re- 
turns, and so the speech consists of a singular series 
of growls and squeaks. 
338. Care of the Larynx.—When the chords are 
in this condition they ought to be used as little as 
possible, or permanent injury to the voice will be 
apt to result. It must be remembered that the mu- 
cous membrane of the larynx in such cases is dis- 
eased and sore, and ought not to be rasped by a 
forcible current of air, or it will not readily recover. 
If one has a sore spot on his hand, he does not rub 
it violently several times a day ; he lets it rest until 
it is well again. In such a case, the pain which re- 
sults from rough treatment is a sufficient indication 
of its harmfulness, but inflamed or congested vocal 
chords are not usually painful, and the use of the 276 
ORGAN OF SPEECH. 
voice is so necessary a part of our daily life that 
every one is too apt to neglect warnings regarding 
it. But Nature is inexorable, and shows no favor. 
Her penalties are severe and unerring. PART VIII. 
STIMULANTS AND NARCOTICS. 
339. Origin of Alcohol.—Alcohol is always the 
product of fermentation. It is produced by the 
growth of the yeast-fungus in matters containing 
sugar, which undergoes decomposition into alcohol 
and carbon dioxide. Whenever a liquid containing 
sugar ferments, alcohol is always produced, so that 
the statement frequently made that small beer, cider, 
weiss-bier, etc., do not contain alcohol, is not true.* 
340. Properties and Composition of Alcohol.— 
Alcohol is a colorless, transparent fluid, of light 
specific gravity (0.7938), is very inflammable, burn- 
ing with a smokeless blue flame, and has never yet 
been frozen, although at exceedingly low tempera- 
* The proportion of alcohol in various liquids may be roughly given 
as follows : 
Whisky, brandy, rum, and gin 50 to 60 per cent. 
Port, madeira, and sherry wines 16 “ 25 “ “ 
Claret wines 7 “ 13 “ “ 
Rhine wines 7 “ 16 “ “ 
Cider 5 “ xo “ “ 
Ale and porter 3 “ 10 “ “ 
Lager-bier 2 “ 5 “ “ 278 
STIMULANTS AND NARCOTICS. 
tures (—1660 Fahr.) it becomes thick and oily. Pure 
alcohol is very difficult to obtain, on account of its 
strong affinity for water. 
It is composed of carbon, hydrogen, and oxygen, 
and therefore, if called a food, would be classed as 
carbonaceous (or as a carbohydrate), and would 
not help to build up tissues largely composed of 
nitrogen, like the muscles and nerves. 
341. Effect of Alcohol on Living Cells.—The 
cells, which compose the mass of the body, being 
very delicate in their structure, are easily acted 
upon and changed in their properties by whatever 
comes in contact with them. The natural fluids of 
the body, in which they are constantly bathed, fur- 
nish them nourishment, and carry away waste mat- 
ters. If other substances besides those contained 
in our natural food and drink are introduced into 
the body and conveyed throughout it by the cir- 
culating fluids, the cells are apt to be injuriously 
affected; and this is especially true of the various 
substances called stimulants and narcotics, of which 
alcohol is the most universally used. Alcohol 
blunts their sensitiveness to external stimuli, re- 
tarding the changes in their interior, hindering 
their appropriation of food and elimination of waste 
matters, and therefore preventing their proper de- 
velopment and growth. The more recently formed 
such cells are, the more marked and persistent is 
this noxious influence; so that in young persons 
who are growing, and in whom all the tissues are 
soft and peculiarly sensitive to all kinds of stimuli, 
the influence of alcohol in any form is especially 
potent and harmful. 
342. Alcohol sometimes a Food.—The question STIMULANTS AND NARCOTICS. 
279 
whether alcohol is a food has been hotly debated, 
but may now be considered settled in the affirma- 
tive, with some qualifications. It is conceded by 
all that pure alcohol, in any quantity and under all 
circumstances, is a poison,* but this is partly on ac- 
count of its irritant effect. Its great affinity for 
water, and its power of coagulating albumen, render 
it destructive of living tissues with which it is 
brought in contact. 
343. Alcohol disappears in the Body.—When 
largely diluted, however, as it is in the various 
alcoholic drinks, alcohol, up to a certain amount, is 
disposed of in the body. When a small quantity 
is taken into the stomach, only a minute trace can 
be detected afterward in the excretions. Most of 
it disappears, and can never be recovered. Exactly 
what change it may undergo is not known, but it 
is believed to be oxidized and converted into carbon 
dioxide and water. This oxidation is really a burn- 
ing of the alcohol, and gives forth heat just as if it 
took place outside of the body, although it is not 
accompanied by flame. 
Alcohol is so easily oxidized that, when it is 
taken into the body in quantities which can be 
physiologically disposed of, a portion at least of 
the other carbohydrates taken with the food are 
not needed to keep up the animal heat, and so they 
are often deposited in the various tissues under the 
Alcohol is not the only substance habitually used as food or drink 
that is poisonous when taken in a concentrated form. Theine and caf- 
feine, the active principles of tea and coffee respectively, are poisons, 
and even common salt, which forms part of the body, and a certain 
amount of which is necessary for health, irritates the stomach and 
causes vomiting when taken in half-ounce doses. 280 
STIMULANTS AND NARCOTICS. 
form of fat. If too much alcohol is taken habitually, 
fat may accumulate in situations where it is not 
only of no use, but of positive harm, interfering 
with the proper functions of organs, and seriously 
impairing the vital resources of the individual. 
344. Alcohol not a Nutritive Food.— In stating 
that alcohol is a food, a distinction must be made. 
It can not be considered a food in the sense of nutri- 
ment. It does not go to build up wasting tissues, 
like the meats, vegetables, and fruits, but it keeps 
up the animal heat, and in some degree prevents 
the waste of tissue. It might thus be called a sup- 
plementary food, or an indirect food, for the follow- 
ing reasons: 
1. Small amounts disappear in the body and are 
not excreted under the form of alcohol. 
2. When no other food is to be had, or can be 
taken (as by sick persons), life may be supported 
for a considerable time on alcoholic liquors, which 
would not be possible if they acted merely as stimu- 
lants. 
3. When alcoholic liquors are taken with meals, 
less food is required to maintain the normal physical 
condition than if no alcohol is taken. 
345. Beverages containing Alcohol.—The ques- 
tion whether alcohol is a food is complicated some- 
what by the fact that it is not usually taken by 
itself or merely mingled with water, but in the va- 
rious wines, beers, and distilled liquors. The latter 
contain so much alcohol and so little of anything 
else except water (if pure), that drinking them is 
very much like drinking diluted alcohol; but the 
wines and beers contain albuminous matters, sugars, 
vegetable acids and salts, which furnish some nu- STIMULANTS AND NARCOTICS. 
281 
triment independent of the alcohol itself. It has 
been found, too, that the moderate use of wine or 
beer does not give rise to the various alterations of 
the structure of organs which render the habitual 
use of distilled liquors (brandy, whisky, rum, gin) 
so dangerous. 
346. What is a Moderate Use of Alcohol ?—The 
question now suggests itself, What is to be consid- 
ered a moderate use of beverages containing alco- 
hol? This is supposed to be determined by finding 
out how much alcohol will be disposed of in the 
body before it can be detected in the excretions. 
Careful experiments have shown that an amount 
of alcohol equal to the one-thousandth part of the 
body-weight is as much as can be assimilated daily 
without injury by a healthy man. 
347. General Effects of the Excessive Use of 
Alcohol.—When more than this is taken the excess 
of alcohol circulates in the blood, and, coming di- 
rectly in contact with the different organs, irritates 
the delicate structures of which they are composed, 
and gradually produces changes in them which can 
mostly be brought under two heads, viz., an in- 
crease of connective tissue, or a deposit of fat. Both 
of these tissues in the healthy body are chiefly use- 
ful on account of their physical properties, the con- 
nective tissue serving as a close-woven web or 
framework to support the softer structures (cells, 
etc.) and retain them in position, while the fat makes 
up the padding of the body, and also is a reserve 
fund upon which the working tissues draw for sus- 
tenance when the amount of food taken is insuffi- 
cient. When these tissues are deposited in abnor- 
mal quantities, however, they become great agents 282 
STIMULANTS AND NARCOTICS. 
of harm. They encroach upon the neighboring 
cells, squeeze them out of shape, interfere with 
their nutrition and the proper performance of their 
functions, and so diminish secretion and excretion, 
press upon and obstruct, or even obliterate, blood- 
vessels, irritate nerves, and in many other ways 
throw the delicate mechanism of the body out of 
gear. These alterations in the structure of organs 
will be more particularly mentioned under the ap- 
propriate headings. 
348. Irritant Effect of Pure Alcohol.—If pure 
alcohol is introduced into the stomach in small 
quantity it acts as an irritant. The mucous mem- 
brane lining the interior of the organ becomes red 
and congested, and there is an increased secretion 
of mucus. If a large quantity be introduced at 
once, the irritation of the nerves of the stomach is 
so great that important nervous centers are affected, 
and extreme depression immediately follows, soon 
ending in death. 
349. Effect of Diluted Alcohol on the Stomach. 
—The effects of diluted alcohol, as in the various 
alcoholic beverages, are different. A moderate 
amount of alcohol, introduced into the stomach in 
this way, produces slight congestion and reddening 
of the mucous membrane and an increased flow of 
mucus, and stimulates the secretion of gastric juice. 
In this way it promotes digestion, and in some per- 
sons of weakly constitutions, with feeble digestive 
powers, a little wine or beer with dinner is found 
to have a beneficial effect, and so far as known no 
injurious one. 
As alcohol coagulates albumen, and when added 
to gastric juice outside of the body precipitates it STIMULANTS AND NARCOTICS. 
283 
and takes away its property of digesting food, it 
might be inferred that it would hinder digestion 
under all circumstances. In small quantity, how- 
ever, it does not, and here experience and observa- 
tion must take precedence of theory. In larger 
amount, however, alcoholic drinks do interfere with 
digestion, often stopping it entirely until the alco- 
hol has been absorbed. 
Alcohol is rapidly taken up by the mucous mem- 
brane of the stomach, and any oxidation or other 
change which may occur takes place in the blood, 
after it has entered the circulation. 
350. Effect of an Excess of Alcohol on the 
Stomach.—If alcohol be taken to the point of in- 
toxication, the reaction, after it has passed out of 
the body, is very marked in the digestive organs. 
The pit of the stomach is tender to pressure, there 
are nausea and retching, with perhaps vomiting of 
mucus and bile. The tongue is heavily coated with 
fur, there is intense thirst, and entire loss of appe- 
tite. These symptoms indicate an acute catarrh of 
the stomach, and may not disappear for several 
hours. 
351. Chronic Disease of the Stomach caused by 
Excess of Alcohol.—When alcoholic drinks are 
habitually taken in excess, the continued irritation 
of the stomach produces serious changes. The 
mucous membrane is permanently congested and 
covered with a thick, unhealthy, tenacious mucus, 
which sets up fermentation in the food, giving rise 
to what is called a sour stomach, heart-burn, and 
nausea, and sometimes vomiting of bile on rising in 
the morning. If the excessive use of such drinks 
is continued, the connective tissue of the mucous 284 
STIMULANTS AND NARCOTICS. 
membrane becom.es greatly developed, the walls of 
the stomach are thickened, the glands that secrete 
the gastric juice are pressed upon and many of 
them starved out of existence, so that the normal 
secretions that are necessary to digestion are scanty, 
and chronic and incurable dyspepsia results. When 
this point has been reached, as in old topers, alco- 
hol is sometimes almost the only food that can be 
taken. 
352. Effect of Alcohol on the Liver.—Alcohol, 
being absorbed by the blood-vessels of the stomach, 
is borne away in the blood to the liver. It reaches 
this organ before there has been time for oxida- 
tion, and is brought directly in contact with the 
structures of which it is composed. At first it 
stimulates the secretion of bile, but if it is used ha- 
bitually in excess the liver becomes the seat of seri- 
ous changes. There may be a great increase of fat 
deposited in the cells, producing what is called by 
physicians the “ fatty liver,” or it may lead to a 
great increase of connective tissue between the cells 
and surrounding the blood-vessels. This newly de- 
veloped connective tissue gradually contracts, and 
in so doing crushes the cells and obstructs the 
blood-vessels, making the organ much smaller than 
natural, and causing the surface to be covered with 
little projecting knobs. A liver thus affected is 
often called a “ hobnailed liver,” from its appear- 
ance, or the “gin-drinker’s liver,” from its supposed 
cause. The pressure upon the liver-cells, and the 
destruction of many of them, prevent the proper 
formation of bile and liver-sugar. The substances 
composing the bile, not being separated by the liver 
with sufficient rapidity, remain in the blood and STIMULANTS AND NARCOTICS. 
285 
give rise to jaundice. • The contraction of the new- 
ly developed connective tissue, by obstructing the 
blood-vessels, interferes with the circulation. The 
blood is dammed back, so to speak, the blood-ves- 
sels of the digestive organs are greatly distended, 
and the watery part of the blood oozes through the 
walls of the vessels into the cavity of the abdomen, 
causing dropsy. The distention of the blood-vessels 
of the stomach is often so great that some of the 
more delicate ones burst and blood escapes into that 
organ. It is turned deep brown or black by the 
gastric juice, and produces nausea and vomiting of 
matters looking like coffee-grounds. This disease 
of the liver, called cirrhosis, is invariably fatal. 
353. Effect of Alcohol on the Blood.—Alcohol 
increases the amount of fat in the blood; exactly 
how, is not known. It also lessens the capacity of 
the blood to absorb oxygen, and in this way inter- 
feres with the nutrition of the body. 
354. Effect of Alcohol on the Nose and Throat. 
—The habitual use of alcoholic drinks in excess re- 
sults in a chronic catarrh of the throat and nose. 
This is especially the case with distilled liquors. 
Probably the direct irritation of the mucous mem- 
brane by the fiery liquid has something to do with 
this. The membrane becomes red, swollen, streaked 
with enlarged veins, and covered with stringy mu- 
cus, which the drinker is constantly trying to get 
rid of by hawking and spitting. This chronic in- 
flamed condition of the throat produces almost con- 
stant thirst, generally gratified by more alcohol, 
which keeps up the irritation it is meant to soothe. 
This inflammation often involves the larynx, giving 
rise to the well-known husky voice of the old toper. 286 
STIMULANTS AND NARCOTICS. 
355- Effect of Alcohol on the Lungs.—Although 
the evidence is conflicting, it is now generally con- 
ceded that alcohol diminishes the excretion of car- 
bon dioxide and watery vapor from the lungsA 
This is probably the result of diminished activity 
of the cells, due directly to the paralyzing effect of 
the alcohol. 
The effect of alcohol upon the lungs of habitual 
drinkers is very marked. The mucous membrane 
becomes congested, and the secretion of mucus 
more plentiful. Colds are easily contracted, and a 
chronic bronchitis results. This finally affects the 
elasticity of the lung-tissue, and the air-vesicles be- 
come in spots permanently distended like little 
bladders. The function of respiration is thus inter- 
fered with, and the sufferer becomes short of breath, 
often asthmatic, is troubled with a constant cough 
and hawking of mucus, so that life is a burden both 
to him and to others. 
356. Effect of Alcohol upon the Heart.—Alco- 
hol stimulates the heart, increasing both the force 
and frequency of the beats. It becomes, therefore, 
a useful medicine when the power of this organ fails 
in disease, or under the influence of sudden and 
powerful emotion. Hardly any stimulant or re- 
storative can be compared with brandy, for a faint- 
ing person, or for one who is in a feeble and pre- 
carious condition from exposure and exhaustion. 
In healthy persons, on the other hand, if the heart 
is constantly stimulated to more rapid contraction 
* According to Binz, pure alcohol (ethylic or common alcohol) does 
not taint the breath. The odor commonly supposed to be that of al- 
cohol is due to the fusel-oils and ethers which impart to the various 
liquors their peculiar flavor. STIMULANTS AND NARCOTICS. 
287 
than is natural, it has less time to rest. Although 
this organ seems to be constantly at work, it really 
rests more than half the time, the time occupied by 
a contraction being to the time between the con- 
tractions about as two to three, so that, although the 
periods of relaxation are very short, they are so 
numerous (seventy or more a, minute) that the ag- 
gregate amount of rest in a day is very great. Now, 
if the rapidity and force of the contractions are in- 
creased materially and continuously, although the 
aggregate amount of time for rest may be the same 
as before, yet the waste caused by the contractions 
is greater (they being more forcible), while the time 
for rest after each one is shorter. This lack of rest 
produces exhaustion of the heart-muscle, ending in 
partial change of the muscular tissue into fat. The 
heart then becomes flabby and weak and its walls 
become thinner, a condition known to physicians as 
a “ fatty heart,” often resulting in sudden death. 
357. Effect of Alcohol on the Blood-Vessels.— 
Alcohol, even in a moderate dose, produces dilata- 
tion of the superficial blood-vessels, probably by 
paralyzing the vaso-motor nerves. This accounts 
for the flushing of the face which follows so soon 
after the drinking of any alcoholic stimulant. This 
dilatation of the small vessels, which produces such 
visible effects on the external surface of the body, 
also takes place in parts hidden from sight. The 
brain, lungs, heart, liver, kidneys, and stomach are 
all congested, and the secretions increased in 
amount. 
358. Diseases of Blood-Vessels caused by Alco- 
hol.—If alcoholic drinks are used habitually, this 
dilatation becomes permanent, partly from their ef- STIMULANTS AND NARCOTICS. 
288 
feet on the vaso-motor nerves, and partly from a loss 
of elasticity in the walls of the vessels themselves, 
owing to a deposit of a fatty nature, which occurs in 
spots between the middle and internal coats, mak- 
ing the walls of the vessels weaker at such points. 
The pressure of the blood produces a gradual 
stretching and thinning of the wall of the vessel at 
these weak spots, resulting in the formation of a 
hollow tumor, like a bladder, on the side of the ves- 
sel, in which the blood eddies round like the water 
in a whirlpool. This disease is called aneurism, and 
is a very distressing and dangerous one. The tu- 
mor presses upon neighboring nerves, causing ob- 
stinate neuralgias and sometimes paralysis, and, 
when the outside coat has become so thin that it 
can resist the pressure of the blood no longer, it 
bursts, and a fatal haemorrhage is the result. 
359. Features of the Habitual Excessive Drink- 
er.—The permanent dilatation of the surface blood- 
vessels produces a permanent flushing of the face in 
drinking men, and often some of the veins are so 
enlarged that they show as red streaks upon the 
features, generally upon the cheeks and nose. The 
white of the eye, for the same reason, becomes red. 
The circulation of the blood in these dilated vessels 
being sluggish, the nutrition of the skin is interfered 
with, and it may be covered with red blotches, or 
disfigured by pimples, especially on the nose. The 
circulation in the latter organ being naturally more 
feeble than elsewhere on the face, it shows these 
effects earlier and more plainly, and sometimes 
becomes almost purple in color and knobbed and 
swollen at the end. 
360. Effect of a Moderate Amount of Alcohol STIMULANTS AND NARCOTICS. 
289 
upon the Nervous System.—The effects of alcohol 
are nowhere more striking- than in the nervous 
system. Immediately upon the introduction of an 
alcoholic drink into the stomach, a sensation of 
warmth is perceived, followed by slight exhilara- 
tion. This is probably due to the irritation of the 
nerves of the stomach, even before the alcohol is 
absorbed. When the alcohol has been taken into 
the blood and reaches all parts of the body, its 
peculiar effects upon the nervous system become 
apparent. There is at first a stage of excitement, 
when the brain seems to be more active, ideas flow 
freely, there is an indescribable feeling of cheerful- 
ness or gayety, a disposition to laugh at trifles, and 
speech is less circumspect than natural. It is this 
property of alcohol that has brought it into use the 
world over, from time immemorial, as a promoter 
of social festivity. Even in this stage of intoxica- 
tion, however, when the activity of the brain seems 
to be increased, when bright people seem more 
brilliant, and witty ones surpass themselves, when 
words and ideas flow most freely, a close and sober 
observer can detect a loss of control, a slight diminu- 
tion of will-power, a slight, very slight lack of cohe- 
rence in trains of thought, and, on the other hand, 
an increased tendency to laugh, to declaim, to joke, 
to banter, which shows a diminution of intellectual 
power and an increased sensitiveness of the emo- 
tional nature, the latter being, however, not an act- 
ual increase, but a relative one, the balance of the 
mind being disturbed, and the dominance of the 
intellect over the emotions being partially sus- 
pended. 
361. Effect of Larger Doses of Alcohol.—If more STIMULANTS AND NARCOTICS. 
290 
alcohol is taken, this diminution of the regulative 
force of the intellect becomes more marked. The 
emotions have free sway. The person becomes 
maudlin, he laughs or cries with equal readiness, 
becomes ludicrously affectionate or causelessly sus- 
picious, he is obsequious in his politeness or obsti- 
nate to rudeness, and his intellect is so far in abey- 
ance that his judgment is lost, he can no longer 
weigh consequences, or reason upon occurrences, 
and is the prey of every suggestion. The move- 
ments of the voluntary muscles are no longer un- 
der control. The currents of force sent along the 
nerves are irregular and inco-ordinate. The tongue 
seems thick and unmanageable, and speech is mum- 
bling and indistinct; the lower limbs are moved 
awkwardly and with a staggering gait; the mus- 
cles of the eyeballs no longer act in unison, but the 
axes of the eyes are guided in different directions, 
and double vision is the result. All of the senses 
are dulled, and the person often suffers injury of 
which at the time he is unconscious. 
362. Effects of a Very Large Dose of Alcohol.— 
If still more alcohol is taken, this condition rapidly 
merges into one of complete insensibility, and the 
drunken man lies like a log, with muscles relaxed, 
with puffing or snoring respiration, with glassy 
eyes, and in extreme cases abolition of all functions, 
excepting those of vegetative life. Such a condi- 
tion may lapse into death, but more frequently the 
alcohol is gradually eliminated from the body by 
the lungs, kidneys, and skin, and recovery takes 
place. 
Such a debauch is followed by extreme nervous 
prostration, with great lassitude, dull headache, STIMULANTS AND NARCOTICS. 
291 
giddiness, and sometimes dimness and yellowness 
of vision on stooping and suddenly rising again, ac- 
companied by the disturbances of the digestive or- 
gans already described. These symptoms clearly 
indicate the action of a poison. 
363. How these Effects of Alcohol are produced. 
—It is believed that alcohol enters into actual combi- 
nation with nervous tissue, and produces the effects 
just described by preventing the normal nutritive 
changes. 
364. Chronic Alcoholism.—When alcohol is ha- 
bitually taken in excess, what is called chronic alco- 
holism is the result. The symptoms of this condi- 
tion are mainly due to the effect of alcohol upon the 
nervous system. The first indication is generally 
muscular tremor, especially on rising in the morn- 
ing. At first this tremor may be stopped by a spe- 
cial effort of the will, but it soon becomes uncon- 
trollable. A glass of spirits, however, will steady 
the muscles, and old topers must always have this 
early in the morning. Soon the sleep begins to be 
disturbed. The person, even if drowsy when he goes 
to bed, tosses restlessly from side to side, unable to 
remain long in one position, not from any pain or 
discomfort, but simply from an indescribable feel- 
ing of disquietude. If he obtains broken snatches 
of sleep, he has frightful dreams. He rises unre- 
freshed, and, even if he attends to his daily occupa- 
tion, is harassed by a constant feeling of dread and 
anxiety for which he can assign no cause. He is 
troubled with noises in the ears and headache. The 
mind becomes seriously impaired ; the will is weak; 
and great uncertainty of purpose is noticed by 
friends, and perhaps by the sufferer himself. When STIMULANTS AND NARCOTICS. 
292 
the chronic poisoning has reached this stage, the 
drunkard is on the verge of delirium tremens. 
365. Delirium Tremens.—This frightful disease 
may be the result of a single prolonged debauch, 
but more commonly supervenes upon a long course 
of drunkenness, or upon a greater indulgence than 
common in persons who call themselves moderate 
drinkers, i. e., persons who daily drink a consider- 
able amount of alcoholic liquor, but who never be- 
come drunk. It may come on during a debauch or 
after its close. The first symptom is absolute sleep- 
lessness. The sufferer is restless and troubled with 
terrifying visions, usually of disgusting or horrible 
objects, black and crawling. He sees insects, rep- 
tiles, or vermin on the floor or creeping over the 
bed. These delusions persist in the daytime, and 
he is constantly occupied with trying to escape, 
pushing them away or resisting them with violence. 
He often hears voices close to his ear, mocking or 
threatening him. He is unable to take food, and 
the muscular tremors above spoken of are incessant 
and distressing. In this pitiable condition he may 
remain for several days, a sight of horror, until 
sleep or death comes to his relief. In the one case 
he generally wakes convalescent, though greatly 
prostrated. In the other he often dies in the midst 
of the most frightful visions, expending the feeble 
remnant of his strength fighting his imaginary foes. 
Chronic alcoholism sometimes produces attacks 
of insanity, in which the unhappy man tries to kill 
himself or others. 
366. Moral Deterioration due to Alcohol.—A 
striking effect of long-continued excessive drinking 
is the moral deterioration it produces. The drunk- STIMULANTS AND NARCO 7 ICS. 
293 
ard loses all the finer and nobler traits of character. 
He becomes untruthful, dishonest, and lazy; he 
loses his relf-respect, and becomes so shameless and 
regardless of the laws of society and the state, that 
he has often to be cast off and disowned by his 
dearest friends for their own protection. Many 
paupers owe their degradation to this alone. 
367. Effects of Alcohol on Nervous Tissue.—It 
has been found that the nervous system of drunkards 
undergoes marked changes which can be detected 
by the microscope. They are of a similar nature 
to those occurring in other parts of the body, viz., 
an increase of connective tissue and of fatty mat- 
ters. The nerve cells and fibers become shrunken 
and wasted ; there may be softening of the brain, 
or small haemorrhages here and there upon its sur- 
face ; the enveloping membranes of the brain are 
thickened, and the whole amount of the brain-sub- 
stance is lessened, the cavity of the skull being kept 
full by the transudation of serum from the blood. 
368. Alcohol diminishes the Power of Endur- 
ance.—It was formerly believed that the use of 
alcoholic liquors enabled men to endure extremes of 
heat and cold better than they could without such 
assistance; but the testimony of travelers, explor- 
ers, and army officers is now overwhelmingly 
against any such proposition. The action of alco- 
hol in paralyzing temporarily the vaso-motor nerves 
results in the overfilling of the capillary vessels and 
a great flow of blood to the surface of the body. 
This gives rise to a feeling of warmth. Every one 
knows that, in blushing, the face is not only red 
but hot. But this very flow of blood to the sur- 
face results in an increased radiation of heat, and STIMULANTS AND NARCOTICS. 
294 
the temperature of the blood becomes lowered. 
Thus the feeling of warmth and comfort produced 
by a dose of alcohol is a deceptive one, for it really 
lowers the temperature of the body,* and thus ren- 
ders it less able to resist external cold. The officers 
of Arctic expeditions are unanimous in their opinion 
that the use of alcohol in cold climates is injurious. 
In hot climates, on the other hand, there is less 
radiation from the body, and less food is required 
to keep up the animal heat. The tissue-changes 
are less active than they should be for perfect 
health, and, as alcohol tends to prevent such 
changes, it increases the pernicious effects of the 
high temperature. In army marches in tropical 
climates it has been found that the drinkers of alco- 
hol do not bear the heat so well as the abstinent, 
and that they are more liable to sunstroke. It has 
also been shown that hard labor, either physical or 
mental, is better done without alcohol than with it. 
This fact is recognized and acted upon in the train- 
ing of athletes and prize-fighters, who are allowed, 
in any case, only a small quantity of such drinks, 
and more frequently none at all. 
369. Other Poisonous Substances in Alcoholic 
Drinks.—The bad effects which have been described 
as due to the excessive use of drinks containing al- 
cohol are increased by the fusel-oil and ethers con- 
tained in them. All liquors distilled from grain, 
potatoes, or other starchy substances, contain fusel- 
oil (or, as it is also called, amylic alcohol). This is 
especially injurious, and delirium tremens and other 
* This is only true of large doses. The smaller amounts, which are 
oxidized in the body, do not lower the temperature, the overfilling of 
the superficial blood-vessels being a symptom of commencing narcotism. STIMULANTS AND NARCOTICS. 
295 
serious derangements of the nervous system occur 
much more frequently in persons who drink liquors 
containing it—such as new whisky and gins, bran- 
dies or wines, which have been manufactured out of 
potato-spirit, or to which it has been added. The 
oil of wormwood, which is found in absinthe, is ex- 
ceedingly dangerous, and rapidly produces in those 
who use it a peculiar form of insanity with muscular 
tremors, giddiness, and epileptic convulsions. These 
oils also develop the various degenerations of or- 
gans much more rapidly than ethylic or common 
alcohol. 
370. Why is Alcohol so generally used as a 
Beverage ?—If alcohol, as has now been shown, is 
not a tissue-building food, if it interferes with the 
normal physiological processes in the body, if it 
does not protect against cold, heat, or disease, but, 
on the other hand, tends to produce almost uni- 
versal degeneration of the organs, to cripple the 
mind and destroy the moral sense; if it produces, 
when used in excess, nervous disorders of the most 
frightful character—why is it so generally used as 
a beverage? Why are men so fond of it? 
Its wide-spread temperate use is undoubtedly to 
be accounted for by its exhilarating effect in small 
doses, and the kindly and generous spirit of mutual 
toleration which it fosters on festive occasions. In 
the promotion of a delightful sociability, no t>ther 
food or drink can be for one moment compared 
with the beverages containing alcohol. Even this, 
its first effect, is due to a partial benumbing of the 
brain. Under its influence all drop for a time the 
mask of conventionality, and enjoy a freedom of 
manner and of conversation which is to most people 296 
STIMULANTS AND NARCOTICS. 
a delicious occasional experience. But this does 
not explain the craving of the drunkard. He does 
not drink for sociability; on the contrary, the con- 
firmed sot often prefers to drink alone, and he 
passes as rapidly as possible through the stage of 
exhilaration into the stage of narcotism, when he is 
dazed, stupid, benumbed, only sensible of the thrill 
that pervades the body as the fiery alcohol bathes 
the shrinking cells. (See Sect. 383.) 
371. Opium not a Food.—Although opium * can 
not be regarded as a food in any sense of the word, 
it is habitually eaten by many people, and in the 
East by whole nations, as the Chinese and Javanese. 
It never acts, however, as a food, but, by its prop- 
erty of blunting the sensitiveness of the nerves and 
nervous centers, it renders the sensations of hunger 
and fatigue less imperious, and so enables persons 
to go longer wdthout food or rest than they other- 
wise could. The lack of food and rest, however, is 
attended with great waste of unreplenished tissue, 
and consequent weakening of the vital forces. 
372. Effect of Opium on the Young.—The great 
difference in the power of resistance between the 
tissues of the young and growing person and the 
adult is strikingly shown by the effect of opium 
upon them respectively. Although this is one of 
the most valuable drugs used by the physician, the 
* Opium is a brownish or blackish gummy substance, obtained by 
evaporating the milky juice of the poppy. Its composition is very com- 
plex, one of the principal substances which it contains being morphia 
(or morphine), usually forming about ten per cent of its weight. Lauda- 
num is an alcoholic tincture of opium, twenty-five drops being about 
the equivalent of one grain of the drag. Paregoric is a compound tinct- 
ure, sweetened with honey and flavored with anise, containing about 
one grain of opium in each tablespoonful. STIMULANTS AND NARCOTICS. 
297 
danger of giving it to children is so great that 
medical books are full of cautions against it, and 
while one grain is an ordinary medicinal dose for 
an adult, and four grains are the smallest quantity 
known to have been fatal to one, infants have been 
killed by one twentieth of a grain. 
373. Effect of Opium on the Stomach.—Opium, 
when taken into the stomach, deadens the gastric 
nerves, and diminishes or entirely suspends the se- 
cretion of the gastric juice. It therefore interferes 
greatly with digestion. By deadening the nerves 
it satisfies hunger. It also in the same way pre- 
vents proper intestinal digestion, produces obsti- 
nate constipation, and thus seriously impairs the 
nutrition of the body. In many people the intro- 
duction of opium into the stomach is followed, after 
the narcotic effects have passed away, by nausea 
and vomiting and great prostration. The same 
symptoms may follow the similar use of morphia. 
If the latter drug is administered by injection un- 
der the skin, so that it is immediately absorbed into 
the blood, the stomach symptoms may be entirely 
absent, and the digestive powers undisturbed.* 
In old opium-eaters, this constant interference 
with the digestion and appropriation of food results 
in extreme emaciation, so that they may look al- 
most like skeletons covered with parchment tightly 
drawn over the bones. In some cases, however, 
even confirmed opium-eaters will recover a certain 
* The injection of morphia under the skin is sometimes followed 
by considerable irritation, and even by a small abscess. If time is not 
allowed for the part to recover its natural condition before a second 
injection, inflammation is almost sure to follow. Hence the trunk and 
limbs of those who take morphia habitually in this way are generally 
covered with abscesses and the scars of those that have healed. 298 
STIMULANTS AND NARCOTICS. 
degree of appetite and digestive power, and the 
constipation be replaced by a diarrhoeal condition. 
374. Effect of Opium on the Lungs.—Opium 
lessens the frequency of respiration and the excre- 
tion of carbon dioxide and water from the lungs. 
It renders the throat and mouth dry by diminish- 
ing the secretion of mucus. In fact, it diminishes 
all the secretions of the body, excepting the perspi- 
ration, which is increased by it. 
375. Difference in Certain Effects of Alcohol and 
Opium.—Opium produces its greatest effect upon 
the nervous system. Unlike alcohol, its use is not 
followed by extensive degeneration of organs and 
tissues, so far as can be discerned by examination 
after death. It must, however, produce a lasting 
alteration of the nerve-cells, or it would not give 
rise to the great psychical changes which invariably 
attend its habitual use. 
376. Effect of a Small Dose of Opium.—A small 
dose of opium, one grain, for instance, is followed in 
a short time by slight exhilaration, soon merging in 
a sense of blissful comfort totally unlike any other 
human experience. There is a feeling of perfect 
rest and composure, absolute freedom from every 
annoyance, while ideas chase each other in rapid 
sequence through the brain, often without apparent 
connection. At first these mental images are of 
an agreeable character, and the individual passes 
through a most delightful, even delicious experi- 
ence. In forty or fifty minutes he grows sleepy, 
and if it be night probably has a good night’s rest, 
though in the daytime he will wake, perhaps, in 
two or three hours. After waking there is some 
depression and disturbance of the digestive organs. STIMULANTS AND NARCOTICS. 
299 
377- Effect of a Larger Dose of Opium.—If the 
dose is larger, two or three grains, it is followed by 
great excitement, with noises in the ears, and the 
ideas are confused and extravagant. The head soon 
feels heavy and dull, the senses are blunted, and 
deep sleep follows, attended by dreams of a dis- 
agreeable nature. The reaction after narcotism has 
passed off is proportionately greater. 
378. Effect of a Dangerously Large Dose.—Aft- 
er a poisonous dose—i. e., a dose which involves 
danger of death—the stage of excitement is very 
brief, there is a sense of giddiness and oppression, 
soon followed by profound sleep. The pulse, which 
at first was full and strong, becomes small and 
feeble. The pupils are strongly contracted, often 
like a pin-point in size. The face is pale, the res- 
piration slow and labored, and the muscles are in 
a state of complete relaxation. Such a condition 
soon passes into death, sometimes preceded by con- 
vulsions. 
379. The Opium-Habit.—The charming visions, 
the sense of ineffable comfort, and the easy flow of 
fantastic ideas produced by a small dose of opium 
in some persons, tempt them strongly to take it 
again. It is at first a luxury, a mere matter of sen- 
sual gratification, but, before the individual is aware 
of the fact, he is the slave of the opium-habit. He 
finds that the agreeable reveries induced by the 
opium he has been taking begin to be replaced by 
others of a horrible or disgusting character. After 
the effects of a dose have passed away, he is gloomy, 
depressed, and wretched, and feels a ravenous gnaw- 
ing of the stomach, which can only be appeased by 
more opium. Then he begins to struggle against 300 
STIMULANTS AND NARCOTICS. 
his chains, and the more hopeless he finds the strug- 
gle the deeper become his despair and gloom. The 
drug no longer affords him pleasure, it merely re- 
lieves his suffering. He takes it now not for enjoy- 
ment, but to escape unspeakable misery, and to his 
horror finds that he must constantly increase the 
dose. 
380. Mental, Moral, and Physical Deterioration 
produced by Opium.—The moral deterioration re- 
sulting from the habitual excessive use of opium is 
fully equal to that caused by alcohol. The opium- 
eater becomes untruthful, slothful, unambitious, and 
careless, wrapped up in the gratification of his un- 
natural appetite, and regardless of the means he 
adopts to satisfy it. 
The memory fails, the temper becomes fanciful 
and capricious, the will is broken, energy disap- 
pears, giddiness, neuralgias, and sleeplessness su- 
pervene, and partial paralysis of the muscles of the 
back and limbs is common, so that the sufferer 
shuffles along bent, shriveled, and weak, like a de- 
crepit old man. 
Death often results from marasmus, or a gradual 
wasting away due to the general failure of nutri- 
tion, the effect of the drug upon the digestive appa- 
ratus. 
381. Effects of the Chloroform-Habit.—Chloro- 
form is eliminated so rapidly by the lungs, that it 
can not be used as a stimulant, like alcohol or opi- 
um, and its habitual use as an intoxicant is for its 
narcotic effect. For some persons the gradual 
lapse into insensibility is attended by such pleasur- 
able sensations that they acquire the habit of inhal- 
ing chloroform to produce it. Its long-continued STIMULANTS AND NARCOTICS. 
301 
use is followed by sleeplessness, tremulousness of 
the muscles, and marked inability to fix the atten- 
tion upon any subject. If its use is persisted in after 
these preliminary symptoms have appeared, it re- 
tards the tissue-changes in the blood and produces 
marasmus and a melancholic form of insanity. The 
drug is a very dangerous one, tending to produce 
sudden death by paralyzing the nervous ganglia of 
the heart. 
382. Effects of the Chloral-Habit.—Chloral in 
moderate doses, fifteen or twenty grains, brings on 
a sleep very much like the natural sleep. The per- 
son can be easily aroused from it, and it is followed 
after waking by no depression or nausea. It thus 
becomes a valuable drug in the hands of physicians. 
If it is habitually used, however, it is followed by 
various disagreeable effects. The blood becomes 
thin and watery, and eruptions or blotches occur on 
the skin ; there is some irritation of the eyes and 
throat, shortness of breath, and pains in the limbs. 
There may be even partial paralysis of the lower 
limbs, and there is great deterioration of the mental 
and moral nature. Death may result from gradual 
failure of the heart, or more commonly from the 
effect of a poisonous dose inadvertently taken. 
383. Cause of the Craving for Narcotics.—The 
unnatural craving, which the drunkard feels, is 
shared by all who become slaves to a narcotic. It 
is to be remembered that all narcotics are stimulant 
at first; that is, they appear to be so on account of 
the benumbing of the higher faculties of the mind. 
Alcohol in large doses is a narcotic, and opium in 
small doses is a stimulant. For our present pur- 
pose, alcohol, opium, morphine, ether, chloroform, 302 
STIMULANTS AND NARCOTICS. 
and chloral are all to be classed together as narcot- 
ics. A striking peculiarity of them all is their tend- 
ency to enslave those who use them to excess, pro- 
ducing a dreadful craving in the sufferer, which 
can only be allayed by a fresh supply and a gradu- 
ally increased amount of the drug. 
This craving is probably due to the fact that 
these poisons enter into loose combination with the 
nerve-substance. This has been shown to be true 
of alcohol, and although the changes produced by 
the other narcotics are not known, the similarity of 
their effect upon the nervous system suggests that 
they may act in the same way. A combination be- 
tween the alcohol and the nerve-matter of cells and 
fibers renders the composition of the nervous sub- 
stance different from normal, but the body accus- 
toms itself, after a while, to the new order of things. 
When the alcohol has been all passed out of the 
body, or disposed of by oxidation in it, the nerve- 
cells are left in a state of disorganization. Disor- 
ganization of cell-structure means the beginning of 
death, and the whole body sends up a cry for re- 
lief. And the relief must be immediate and easily 
attained in order to abate suffering. If the drunk- 
ard, whose nervous system has fallen into this state, 
in which the cells are not in working order unless 
combined with alcohol, can be prevented from ob- 
taining it for a considerable time, the cells will 
gradually appropriate material from other sources, 
and, after a time, resume their normal condition. 
Then the craving ceases. 
The craving, therefore, is a compound feeling. 
It results partly from habit (and the alcohol-habit is 
tyrannous, as many other habits are), and partly STIMULANTS AND NARCOTICS. 
303 
from the fact that the effect of alcohol is so imme- 
diate and pronounced, so perceptible to the indi- 
vidual himself, whereas ordinary wholesome food 
and drink, after they have entered a healthy stom- 
ach, have practically disappeared forever, so far 
as any special physical delight is concerned. The 
eating of food appeases hunger and at the same 
time gratifies the palate, but when the hunger is ap- 
peased the pleasure of the meal is ended. Not only, 
however, is the drunkard’s hunger appeased by alco- 
hol, but the effect of what he has taken into his 
stomach continues to be perceived, in a pleasurable 
degree, until unconsciousness supervenes. 
This craving for narcotics is the most terrible 
fact connected with their use. It constitutes a slav- 
ery of the most dreadful kind. It is more hope- 
less in some cases than in others. The chains of 
the alcohol slavery may be broken. Many a drunk- 
ard is reclaimed. But that of opium is pitifully 
lasting. Few ever escape from the toils. It is 
even doubtful if any do, when the net is once 
fairly cast about them. 
384. Present Teachings of Science regarding 
Stimulants and Narcotics.—The following may be 
regarded as the present teachings of science with 
regard to the use of stimulants and narcotics: 
1. That alcohol, in small doses, is oxidized and 
destroyed in the human body. 
2. That alcohol does not build up wasting tis- 
sues, and is not to be looked upon as a directly 
nutritive substance. 
3. That alcohol, by its oxidation, supplies heat 
to the body, and enables it to utilize the carbohy- 
drate elements of the food in other ways, so that 304 
STIMULANTS AND NARCOTICS. 
it may be considered a supplementary or indirect 
food. 
4. That in certain cases of illness, and in some 
delicate and weakly persons, alcohol constitutes a 
valuable addition to the diet, on account of the 
rapidity and ease with which it can be utilized. 
5. That the amount of alcohol which can be 
taken by a healthy person daily and disposed of 
without injurious consequences is about one-thou- 
sandth of the body-weight, this being the extreme 
limit, and two thirds of this amount are considered 
by Dr. Parkes to be the limit of safety ; i. e., for a 
man weighing one hundred and fifty pounds, about 
one and one half ounce of absolute alcohol, equiva- 
lent to one pint of wine (ten per cent alcohol), or 
two pints of beer (five per cent alcohol). 
6. That alcohol in excess of this amount is not 
assimilated, but circulates in the blood, and is final- 
ly ejected lrom the body by the skin, kidneys, and 
lungs. 
7. That such excess of alcohol acts as a narcotic 
and an irritant to the tissues, and produces serious 
degenerative changes in the organs, tending to 
shorten life. 
8. That these degenerative changes are more 
common and more serious in those who use dis- 
tilled liquors than in those wTho only drink wine or 
beer, and are least in those w<ho drink wine alone ; 
that they are particularly liable to follow the use 
of alcoholic beverages containing fusel-oil, such as 
new whiskies and rums, brandies, gins, or wines 
manufactured from or fortified with potato-spirit. 
9. That alcohol diminishes the power of endur- 
ing cold and heat and fatiguing labor; that it does STIMULANTS AND NARCOTICS. 
305 
not protect against malaria, or against epidemic dis- 
eases. 
10. That, excepting in the cases mentioned above 
(4), alcohol is not to be regarded as a food, but as 
a luxury, and, in view of the danger attending its 
habitual use, healthy people are much better off 
without it. 
11. That opium, chloroform, chloral, ether, and 
alcohol in narcotic doses, are always to be looked 
upon as drugs, and never to be taken excepting by 
the advice of a physician, and then with a full ap- 
preciation of the danger involved in their use. QUESTIONS. 
PART I. 
Chapter I.—1. What is anatomy? Physiology? Hygiene ? What 
is an anatomical element? A tissue? An organ? A system? An 
apparatus ? Give examples of each. What is the function of an or- 
gan? 
Chapter II.—2. What is the minute structure of the body? Which 
is the original element ? What causes the different consistency of dif- 
ferent organs? 3. What is a fiber? Where found? 4. Why is the 
cell so important ? What is a cell? Nucleus? Nucleolus? 5. What 
is protoplasm ? How large are cells ? 6. What other kind of matter 
exists in the body ? 7. What is the difference between living and dead 
cells? Illustration? 8. How do cells increase in number? 9. What 
other powers do cells possess? How are wounds healed? What is 
said of “ proud flesh ” (foot-note) ? Does one cell ever perform the 
duty of another ? Give example (foot-note). 
PART II. 
Chapter I.—10. Why are bones necessary? 11. How does living 
bone differ from dead bone ? 12. What is the composition of bone r 
What experiments will show this? 13. How are bones affected by 
age? What is a “ green-stick ” fracture ? 14. How many kinds of 
bones are there ? What is the structure of the shaft ? Of the extrem- 
ities? Why the difference? What is the marrow? 15. What is the 
periosteum? What is the minute structure of bone? 16. What is the 
use of the periosteum ? Illustrate. 
Chapter II.—17. How many bones in the body ? What is ossifi- 
cation ? When complete ? 18. What is the spine ? What is a vertebra ? 
How are the vertebrae arranged in the spine ? What separates them ? 
How is the spinal canal formed, and what does it contain ? 19. How QUESTIONS. 
movable is the spine ? How is it held together ? What is the use of 
the pads between the vertebrae ? Is a man taller in the morning or at 
night? Why? 20. What is the skull ? How are its bones peculiar? 
What is the advantage of its arched shape ? What movable bone in 
the skull ? 21. What are the sutures of the skull ? What is thei. 
use? 22. What are the frontal sinuses? How may they cause head- 
ache ? 23. Describe the ribs. How many are there ? How are they 
attached to the breastbone? What are the floating ribs? How does 
the motion of the ribs alter the form of the chest ? 24. How do the 
cartilages of the ribs change with age ? How does pressure affect 
them? What is the natural shape of the chest? 25. How many bones 
are there in the limbs ? What is meant by homologous bones ? 26. 
How are joints formed ? What is cartilage ? Synovial membrane ? 
Ligaments? Uses of these parts. 
Chapter III.—27. What is a fracture? A dislocation ? How can 
they be told apart ? 28. How are bones generally broken, and why 
does the limb generally become shorter after a fracture? Why is a 
fracture near a joint so serious ? 29. Why is a dislocation so painful i 
In what joints are dislocations most common ? How are they generally- 
caused? What is a sprain (foot-note) ? 30. How long does it take a 
broken bone to unite? 31. How should a broken limb be cared for 
before the doctor comes ? How can the patient be carried ? 
Chapter IV.—32. How are the bones moved? What two kinds 
of muscle are there ? 33. What is a voluntary muscle ? What is con- 
nective tissue (foot-note)? Use of muscle. How does voluntary mus- 
cular fiber look under the microscope ? What is striation ? 34. What 
is the minute structure of involuntary muscular fiber? 35. How do 
voluntary and involuntary muscles differ in their action ? Peculiarity 
of the heart-muscle. Where are involuntary muscles found ? 36. Do 
muscles vary much in size ? Illustrate. 37. How are the muscles con- 
nected with the bones ? What is a tendon ? Describe the peculiar 
arrangement of tendons at the wrist and ankle. 38. Describe the dis- 
advantages under which a muscle exerts its force during contraction. 
39. What is the irritability of muscle ? Give illustrations. 40. What 
is meant by the muscular sense ? Of what use is this sense ? 41. Illus- 
trate the use of this sense in standing. 42. What is the effect of con- 
traction on the muscle itself? 43. What is the effect of muscular over- 
work ? 44. What is the result of muscular inactivity ? Give illustra- 
tions. How is curvature of the spine produced (foot-note)? 45. What 
is the best exercise ? What is said of gymnastic training ? 46. Why is 
exhaustion dangerous ? 47. Why is rest necessary ? What simple rules 
for exercise are given ? QUESTIONS. 
309 
PART III. 
Chapter I.—48. Why do we need food ? 49. Can people live 
without eating ? Why ? 50. What are the two great divisions of foods ? 
51. What proportion of the body is water ? How much water is need- 
ed daily ? 52. Illustrate the importance of salt (foot-note). 53. What 
other inorganic substances are taken in food ? Why is lime so impor- 
tant? 54. What are the non-nitrogenous foods ? 55. In what foods is 
starch found ? What peculiarity has starch ? 56. In what foods is 
sugar found? Name some of the varieties of sugar. What is said of 
glucose (foot-note)? 57. What is the use of fat in the body? Is the 
fat all taken into the body with the food ? What articles of food tend 
to produce fat ? Illustrate. Describe Mr. Banting’s case (foot-note). 
58. What are nitrogenous foods? What other name are they known 
by to physiologists ? In what foods are the nitrogenous substances 
found? Are similar substances found in vegetable foods? 59. Why 
do we need variety in our food ? 60. Which is the most essential of all 
articles of food or drink? Illustrate. 61. How much of each kind of 
food is needed daily ? 62. What is the effect of cooking on food ? 
Chapter II.—63. What is the use of the digestive apparatus ? 
64. What are the five stages in the preparation of food for the needs of 
the body? 65. Which of these stages is under control of the will? 
Why must all the stages be properly carried through? 66. Use of the 
senses of taste and smell. 67. Use of the teeth. Of the cheeks and 
tongue. What is the masseter muscle? What is said of the sound 
accompanying muscular contraction ? 68. What is the saliva ? What 
are the parotid glands ? How does their secretion differ from that of 
the other salivary glands ? Does the secretion of saliva vaiy in amount 
at different times ? Illustrate (foot-note). 69. What are the properties 
of the saliva ? Its effect upon starch ? Its use in the preparation of 
food. Illustrate. How much saliva is secreted daily ? What is said 
of the care of the teeth (note) ? 
Chapter III.—70. What is the alimentary canal? 71. What is 
mucous membrane? Its minute structure? What are epithelial and 
epidermal cells (foot-note) ? 72. Describe the character and arrange- 
ment of the muscles in the alimentary canal. What is the result of 
their contraction ? 73. What is serous membrane ? Its use ? 74. 
What are the pharynx and oesophagus? How do we swallow ? 75. 
How large is the stomach ? What is its shape ? Where are its two 
openings, and what are they called ? What is the great pouch of the 
stomach? In what direction do substances pass through the stomach, 
and how is this regulated? 76. What portions of the food are digested 310 
QUESTIONS. 
in the stomach ? 77. Describe the accident to St. Martin, and its re- 
sult. 78. What is the appearance of the interior of a healthy stomach ? 
79. How does the gastric juice appear during secretion ? When is it 
secreted? 80. What two necessary ingredients has the gastric juice? 
Can food be digested outside of the body? How much gastric juice is 
secreted daily ? 81. What part do the muscles of the stomach perform 
during digestion? 82. What is the appearance of the interior of the 
stomach during indigestion? Is the gastric juice secreted at such 
times ? How is the tongue affected ? 83. How long a time is re- 
quired for stomach-digestion ? 84. How does thorough mastication 
assist digestion, and why ? 85. What is said of eating too little ? 86. 
Why is it harmful to eat too much ? 87. Why should we not eat be- 
tween meals? 88. What is hunger? Why is plain food the best? 
89. How are we to know when we have eaten enough? How far 
apart should our meals be? 90. How are we to judge of what to eat ? 
91. What is said of pepper and mustard? What is the golden rule 
about eating? 92. What is the natural drink ? 93. What are the im- 
mediate effects of drinks containing alcohol ? 94. What is the pecul- 
iarity of narcotic poisons ? 95. What is the earliest symptom of nar- 
cotic poisoning ? 96. What is the effect of alcohol on growing persons ? 
97. What are the effects of habitual excess in the use of alcoholic 
drinks ? 98. What effect has alcohol upon the powers of endurance ? 
Does it enable men to bear heat and cold better? Why does it seem 
to ? Does it ward off disease ? 99. What effects have tea and coffee 
on growing persons ? Also tobacco (foot-note) ? 100. How is candy 
adulterated? What kinds are to be avoided? Why? 101. What is 
the trichina spiralis ? The cysticercus cellulosre ? How can they be 
killed ? What are the general rules about eating ? 
Chapter IV.—102. What becomes of the fats, sugars, and starches 
in the stomach? What is the chyme? 103. What is the structure of 
the small intestine ? How does it join the large intestine ? What is 
the course of the latter ? What is the appendix vermiformis (foot-note) ? 
104. How do the muscular fibers of the intestine contract ? What is 
the result? 105. What is the duodenum? 106. What is the pan- 
creas? What is its use? 107. What is the liver? Its secretion? 
108. What other function has the liver? 109. What is the bile ? 
Where is it discharged into the intestine ? What reason is there for 
supposing that it is an excrementitious fluid? What is jaundice? 
What is the result if the bile is prevented from entering the intestine ? 
Illustrate. Does the bile leave the body ? What is the inference from 
these facts? no. What are the intestinal juices ? How are they use- 
ful? in. How is it shown that food is absorbed from the intestine ? QUESTIONS. 
311 
What vessels absorb it ? Origin of the name lacteal (foot-note) ? 112. 
What is the peritonaeum? Its use? How do the blood-vessels and 
lacteals get to the intestine ? Where do they terminate ? 113. What 
are the villi? Their size, number, and structure ? 114. What are the 
lymphatics? The lymph? The lymphatic glands? What is the 
function of the lymphatics? What are the lacteals? The thoracic 
duct? 115. Where is the blood from the intestines carried? 116. 
What is the function of the villi ? What is the chyle ? How is it 
absorbed (foot-note)? 117. Describe the changes in the blood during 
digestion. 118. What is the spleen? Why would it seem to be an 
important organ ? What is the result of its removal ? What is prob- 
ably its function (foot-note) ? 
Chapter V.—119. What is the blood? Its physical properties? 
120. What are the red blood-corpuscles ? Their appearance and size ? 
How do they differ in different animals? 121. What are the white 
blood-corpuscles ? How numerous are they ? What is their appear- 
ance and size ? How much of the blood is made up of corpuscles ? 
122. What is the plasma? Its composition? 123. What is coagula- 
tion ? What is the clot ? The serum ? Why is the clot red ? How 
does serum differ from plasma ? 124. What conditions affect the 
rapidity of coagulation ? Will blood coagulate inside of the body ? 
Illustrate. 125. What is the total amount of blood in the human 
body? 126. What gas is absorbed by the blood from the air? How 
important is it to life? Illustrate. 127. What process causes the blood 
to change color? 
Chapter VI.—128. Is respiration a simple process? 129. What 
is the structure of the interior of the nose ? Why is it better to breathe 
through the nose than through the mouth ? 130. What is the trachea ? 
What are the bronchi ? How are these tubes kept open ? Do the 
rings of the trachea entirely surround it ? Why not ? What is the 
larynx? What is the glottis ? Where is it situated ? 131. What are 
the vocal chords ? What is the epiglottis ? Its use ? 132. What are 
the lungs, their situation, appearance, and weight ? 133. What is the 
minute structure of the lungs ? What is a pulmonary lobule ? A pul- 
monary vesicle ? Their size ? 134. What peculiarity has the lining 
membrane of the lungs? What is the function of the cilia? 135. 
What is asthma? 136. Where are the blood-vessels of the lungs 
situated? 137. What is the pleura? Its use? What is pleurisy? 
138. How is inspiration effected? What are the situation and use of 
the diaphragm ? What is hiccough (foot-note) ? 139. How is expira- 
tion effected ? 140. Which is the more powerful action, inspiration or 
expiration ? 141. How much air is taken into the lungs with each in- 312 
QUESTIONS. 
spiration ? What is the entire capacity of the lungs ? How much air 
can be expelled with a forcible expiration ? 142. What is meant by 
the diffusion of gases? What is the function of the cilia? How is 
the air in the lungs changed otherwise than by respiration ? 143. How 
much air is respired daily? How would you calculate the amount? 
144. What is the composition of air as it enters the lungs ? How is it 
changed there? How much water is expired daily ? 145. How much 
oxygen disappears in the body? How was the carbon dioxide for- 
merly supposed to be formed ? How can this theory be disproved ? 146. 
What gives the breath its peculiar odor? 147. How is the blood changed 
in the lungs ? What is the cause of the change in color (foot-note) ? 
148. Where is the carbon dioxide found ? How much is expired daily ? 
149. How is the air changed by respiration? Importance of moisture 
in the air (foot-note). 150. Effect of plants on the composition of the 
air. 151. How does the air of houses become unfit to breathe? What 
is the effect of combustion? What is the most dangerous impurity 
added to the air by the breath? 152. What is ventilation ? How can 
it be effected ? What becomes of the organic matter of the breath in 
the open air? 153. What are contagious diseases? How are they 
communicated from one person to another? Malarial fevers, sewer- 
air (foot-notes). 154. How are these diseases prevented from spread- 
ing? What precautions are to be taken in the sick-room? And why? 
Chapter VII.—155. What is asphyxia? How produced? How 
is the color of the surface of the body affected by it? 156. How long 
may a person remain under water without dying? 157. What should 
be done to resuscitate a person who has been under water until he is 
unconscious? And why? 158. What is the object of artificial respi- 
ration? Describe the method of performing it. What is the first sign 
of recovery? 159. What precautions are necessary with regard to the 
throat and tongue ? What should be done when the person begins to 
breathe ? Importance of fresh air (foot-note). 
Chapter VIII.—160. How is the circulation of the blood effected ? 
161. What is the heart? Its situation? What is the pericardium? 
162. Describe the double circulation. 163. Describe the course of the 
blood in the two sides of the heart. Why does the blood always go 
forward and never backward ? 164. How is each side of the heart 
divided? How many cavities are there altogether? What are they 
called? What is the course of the blood through them? 165. How 
many sets of valves has the heart ? Where are they situated ? What 
is their use? 166. What large blood-vessels are connected with the 
heart? 167. Describe the circulation of the blood more fully. 168. 
What peculiarity in the arrangement of certain valves in the heart ? QUESTIONS. 
313 
And what is the effect of this peculiarity ? 169. How does the heart 
contract and relax? 170. What are the sounds of the heart? How 
are they produced? 171. How frequently does the heart contract? 
How may the rapidity of contraction vary, and what conditions affect 
it ? Can its contractions ever be controlled by the will ? Give illus- 
tration. 
Chapter IX.—172. How is the work of the heart assisted? 173. 
What is the structure of the arteries ? How many layers ? What is 
the use of the elastic fibers? 174. How is the pulse produced? Where 
can it be felt ? 175. How do the arteries divide into branches, and how 
do their walls change as they become smaller ? 176. What are the 
capillaries? How large are they? How numerous? Illustrate. 177. 
What is the structure of the veins ? What is the result of their struct- 
ure ? What are the venae cavae? 178. What effect has respiration on 
the flow of blood in the veins ? And how ? 179. What effect has mus- 
cular contraction? And how? 180. What is the use of the valves in 
the veins? How can this be illustrated? 181. How do the capillaries 
assist the venous flow? 182. What is said of communicating blood- 
vessels? 183. Give a brief review of the course of the circulation. 
How rapidly does the blood flow in the arteries? How rapidly in the 
capillaries ? Describe the circulation as seen in the frog’s foot. 184. 
What artery carries black blood, and what vein scarlet blood ? And 
why? 185. How rapidly does the blood flow in the veins? Why is 
not the rapidity of the blood-current the same in arteries and veins? 
186. How rapid is the general circulation ? What experiment has 
been made to determine this? How long does it take for all of the 
blood to pass through the heart ? How is this calculated ? 187. What 
are the vaso-motor nerves ? How do they affect the circulation ? 188. 
What is the aorta ? What is its course ? 189. What are the femoral 
arteries? Their course ? 190. What are the brachial arteries ? Their 
course ? The radial and ulnar arteries ? 191. What arteries supply 
the head and face ? What is the course of the carotid arteries ? 192. 
Where are the veins usually situated? What are the jugular veins? 
What other large and important veins are there ? How many pulmo- 
nary arteries? How many pulmonary veins? 
Chapter X.—193. What happens when the circulation of blood in 
any part of the body is obstructed ? Illustrate. How is the swelling 
caused? What is dropsy? What happens when the obstruction is re- 
moved? 194. What is the result of disease of the valves of the heart ? 
How is shortness of breath produced ? How is general dropsy pro- 
duced by such disease ? What is the result of disease of the aortic 
valves? What may result from inflammation of the edges of*the 314 
QUESTIONS. 
valves? How may gangrene be caused? 195. How do physicians 
detect heart-disease ? 196. Effect of coagulation on bleeding. 197. 
What are some of the conditions of coagulation ? Illustrate. 198. 
How can the bleeding from an artery be distinguished from that from 
a vein ? 199. How does Nature stop haemorrhage? 200. How docs 
cold arrest bleeding ? 201. What are styptics ? Name some of them. 
What is their effect on the blood ? What is the objection to their use ? 
202. How is compression applied to a wound ? Where should an ar- 
tery be compressed? And a vein? 203. How does Nature arrest 
bleeding permanently? How do surgeons assist the process? What 
is the use of ligatures? 204. State briefly the means of arresting 
haemorrhage. 205. How is bleeding from wounds of the limbs to be 
stopped? How is the knotted handkerchief to be used ? 206. What 
is the cause of fainting, and what is to be done for it ? 207. What 
does shortness of breath always indicate ? Why does exercise cause it ? 
PART IV. 
Chapter L—208. What is said of the difficulty of investigating 
the nervous system? 209. What are the two great divisions of the 
nervous system ? What are they called ? What are their functions ? 
210. What are the two forms of nervous tissue? 211. What is the 
structure of the white substance? How large are nerve-fibers ? What 
is the myelin ? The axis-cylinder ? What are supposed to be the func- 
tions of these different parts of the nerve-fiber? 212. What does the 
gray substance consist of? How large are nerve-cells? What is their 
structure ? What relation is supposed to exist between the cells and 
the fibers ? What is the function of the fibers ? What of the cells ? 
213. What is the structure of a nerve? How do its constituent parts 
vary in different situations? What kind of nervous substance is most 
abundant? 214. What are nervous ganglia? 215. Illustrate the func- 
tions of sensation and motion as exhibited by nerves. What is reflex 
action? Why so called? 216. What is said of the rapidity of the 
nervous force? Give an illustration. 217. Do nerves become ex- 
hausted? How? 218. How can it be shown that nerves are mere 
conductors of force? 219. What are the reasons for believing that the 
gray substance originates force ? How does the nerve-force differ from 
electricity ? 220. What part of the nervous system supplies the volun- 
tary muscles with nerves? And what part the involuntary ones ? What 
part is under our own control ? 
Chapter II.—221. What is the structure of the sympathetic sys- 
tem? How large are the ganglia? Where are they situated? What QUESTIONS. 
315 
is said about the solar plexus (foot-note) ? 222. What is said of the 
rapidity of action of the sympathetic system ? How is it illustrated in 
disease ? 223. How is it illustrated by the pupil of the eye ? 224. 
What is the effect of dividing a sympathetic nerve ? How may it be 
shown on the ear of a rabbit? What do these facts indicate? 225. If 
the sympathetic nerve supplying a gland is divided, what effect is pro- 
duced? How is “watering of the mouth” caused? 226. How is 
blushing produced? Why is it more evident in the cheeks? What 
facts show that it is regulated by the sympathetic nerves ? How can 
the blush be prevented? 227. What are the vaso-motor nerves? Why 
so called ? Are the cerebro-spinal and sympathetic systems entirely 
distinct from each other ? 228. What system regulates the process of 
digestion ? How may this process be affected by the emotions? 229. 
What effect has cold on the sympathetic nerves ? How may serious 
disease be brought on by exposure? How do persons catch cold, and 
how may colds be prevented (foot-note)? 230. What are the signs of 
exhaustion of the sympathetic system ? How is it to be relieved ? 
Chapter III.—231. Describe the spinal cord. How are the gray 
substance and the white substance arranged respectively? What are 
the fissures of the cord? 232. How many pairs of spinal nerves are 
there? What parts of the body do they supply ? 233. What are the 
properties of the spinal nerves ? 234. What two kinds of sensibility 
exist in these nerves? How is this shown? 235. What is the effect of 
dividing a spinal nerve ? How can sensation and motion both be con- 
veyed by the same nerve ? 236. How many roots has a spinal nerve ? 
How does the posterior root differ in appearance from the anterior ? 
How are the spinal nerves formed, and how do they divide ? 237. What 
effect is produced by dividing the anterior roof of a spinal nerve ? What 
does this experiment prove? 238. What effect is produced by dividing 
the posterior root of a spinal nerve ? What does this experiment prove ? 
239. What do these experiments show with regard to the structure of 
spinal nerves? 240. How is the spinal cord connected with the brain? 
What is said of the crossing of fibers from one side to the other? 241. 
Why are sensations always referred to the extremity of the nerve ? 
Give illustrations. 242. What is the use of the gray matter in the 
center of the spinal cord? Describe the experiment with the frog. 
What does it show ? 243. How does Nature perform similar experi- 
ments for us upon men? Illustrate. 244. What are automatic ac- 
tions? Illustrate.- 
Chapter IV.—245. What is the distinction between the brain and 
the cerebrnm ? What is said of the removal of the cerebrum ? 246. 
What is the structure of the cerebrum ? What are the convolutions ? 316 
QUESTIONS. 
How is the gray matter distributed ? Is the cerebrum sensitive to in- 
jury ? 247. What is the function of the cerebrum ? 248. Does intel- 
ligence seem to increase with the size of the brain ? Illustrate. What 
is the weight of the human brain ? 249. How much do human brains 
differ in weight? Illustrate. How would you account for a small 
brain in a clever man ?. 250. What effect do injuries of the brain have 
upon the mind ? 251. What is the effect of removal of the cerebrum 
of a pigeon ? 252. What is the effect of softening of the cerebrum in 
man? 253. State briefly the evidence that the cerebrum is the seat of 
intelligence. 254. What is the structure of the cerebellum ? Its size ? 
255. What is the effect of removal of the cerebellum of a pigeon? 
What does this experiment seem to show? What is the effect of dis- 
ease of this organ in man ? What is inferred from these facts as to 
the function of the cerebellum ? 256. What is the function of the 
tubercula quadrigemina ? How can this be proved ? Where do the 
powers of sensation and motion reside? How is this shown? 257. 
Describe the situation and relations of the medulla oblongata. What 
is the vital knot ? 258. How are the movements of respiration regu- 
lated by the medulla oblongata ? 259. Illustrate the automatic action 
of this ganglion. What is the result of its destruction ? 
Chapter V.—260. How do the nerves of the brain differ from the 
spinal nerves ? Which are the most important ones ? What parts does 
the trigeminal nerve supply ? What is its function ? What parts are 
supplied by the facial nerve ? What is its function ? How may it be 
affected by exposure to cold ? 261. What is the course of the sciatic 
nerve? What is the cause of the foot “being asleep”? 262. What 
is the importance of reflex action? Give illustrations (foot-note). 
263. Why is education so important ? Why are habits easily formed 
in the young? Why do they need the guidance of older persons? 
264. Why is it important that the brain should have sufficient exercise ? 
265. What is the effect of over-exercise? 266. Why is sleep necessary? 
What takes place during sleep ? Why do we wake up ? What is the 
best time for sleep? Why? How much sleep is necessary ? 267. What 
is said of abuse of the nervous system, and its danger? 
PART V. 
Chapter I.—268. In what points do the skin and mucous mem- 
brane resemble each other ? What are the functions of the skin ? 269. 
What is the structure of the skin ? The epidermis ? The derma ? 
How thick is the skin ? 270. How is the skin connected with the tis- 
sues beneath it? What are the papillae? Their situation, size, and QUESTIONS. 
317 
arrangement? 271. What causes the difference of complexion in dif- 
ferent persons? What is an albino ? What seems to be the use of the 
pigment-cells ? 272. What are the nails ? How do they grow ? What 
is the use of them? 273. What are the hairs? How do they grow ? 
What causes the difference in color of the hair in different persons ? 
How much of the body is covered with hair? 274. What are the seba- 
ceous glands ? What is their structure ? Where are they situated ? 
What is their function ? What is the result when their openings are 
obstructed? 275. What are the sweat-glands? Where are they situ- 
ated ? What is their structure? How large are they, and how nu- 
merous ? 
Chapter II.—276. What is the effect of pressure on the skin ? 
What diseases may be produced by it ? 277. What was Lavoisier’s theory 
of the cause of animal heat? How overthrown? Liebig’s theory? 
What objection is there to it? What is believed to be the true theory ? 
278. What is the normal temperature of the human body ? How much 
may it vary ? 279. What is the effect of a great fall or a great rise in 
the temperature of the body ? What external temperatures are we 
often exposed to ? 280. What is the effect of a low external tempera- 
ture on the body? How is the appetite affected? How does the body 
accommodate itself to such a temperature ? 281. What is the effect 
upon the body of a high external temperature ? 282. How is the tem- 
perature of the body regulated by the perspiratory glands ? 283. Whr.t 
is the insensible perspiration? What is its daily amount? How may 
it be immensely increased ? 284. What is the effect of exposure to dry 
heat? 285. What is the effect of exposure to moist heat? 286. What 
is said of respiration through the skin ? How much carbon dioxide 
is thrown off by it (foot-note) ? What is said of absorption through the 
skin (foot-note) ? 287. How does the skin become covered with im- 
purities ? Why should these be removed ? 288. What is the effect of 
a cold bath ? How long should the bath last ? 289. What is the effect 
of a warm bath ? Why should exposure to cold be avoided after it ? 
290. State the rules for bathing and the reasons for them? 291. How 
should the face and hands be cleaned? What is the objection to soap? 
How is “ chapping” produced? How may it be prevented ? What is 
the best soap ? 292. What causes dandruff? How should the scalp 
be cleaned ? What is said about cleaning and cutting the hair? 293. 
How should the nails be cut? Why should they not be cut close to 
the flesh ? What causes “hangnails”? How may they be prevent- 
ed ? What causes the white spots on nails? 294. What is the object 
of clothing ? What is the best material to wear next the skin ? Why ? 
Why is linen bad for this purpose ? Why should the under-clothing be 318 
QUESTIONS. 
changed at night? What is said of tight and high-heeled shoes? 
What are the general rules for the selection of clothing ? 
PART VI. 
CitAPTER I.—295. Where does the sense of touch have its seat? 
How do the nerves end in the papillae of the skin ? 296. What do we 
learn by the sense of touch ? How does the sensitiveness of the skin 
vary in different parts of the body ? How is this shown? What is the 
most sensitive part (foot-note) ? 297. Can the extremes of sensation 
be easily distinguished from each other? What is said of deception 
through the senses? Give illustrations (foot-note). 298. What rela- 
tion do the special senses bear to the sense of touch ? What pecul- 
iarity is common to them? 299. Where is the sense of taste located? 
How are the nerves of taste distributed to the tongue ? How do they 
terminate ? How do we taste ? 300. How many modifications of the 
sense of taste are there? What qualities are perceived in the mouth 
by the sense of feeling? Is the aroma of a substance tasted or smelt? 
How may this be determined ? 301. Why do substances have a dif- 
ferent taste on the front and back of the tongue ? Give illustrations. 
Why does the sensation of taste persist for a time after the substance has 
been removed ? How does this affect the detection of delicate flavors ? 
Why do we smack our lips when tasting? What is the use of this 
sense? 302. Where does the sense of smell reside? What is the 
olfactory nerve ? Its situation ? How much of any substance is re- 
quired to affect the sense of smell? Why do we sniff at odors in order 
to appreciate them (foot-note)? Illustrate the occasional difficulty 
of distinguishing between the sense of smell and that of feeling? 
303. Illustrate the acuteness of this sense in some men and lower ani- 
mals. What is the use of this sense ? 
Chapter II.—304. What kind of impressions are perceived by the 
sense of hearing? 305. What are the three divisions of the ear? What 
is the use of the external ear ? Is it movable ? 306. What is the tym- 
panum ? How do the air-waves reach it ? What is the middle ear ? 
Its situation and size ? What is the Eustachian tube ? Its use ? 307. 
Where are the bones of the ear? How many are there, and how large? 
What are they attached to, and how are they moved ? 308. What is 
the structure of the internal ear? What are its chief parts, and what 
is it filled with? How is the nerve of hearing distributed? 309. How 
is hearing affected? 310. Upon what do the different qualities of 
found depend? 311. How do we determine the direction from which 
sound comes ? What is said of the function of the semi-circular canals 
(foot-note)? 312. What is ventriloquism? How are its effects pro- QUESTIONS. 
319 
duced? 313. How is the ear protected from insects? How can they 
be removed when they have entered the ear? What is said of the use 
of ear-scoops ? 314. How may colds in the head affect the hearing ? 
How may permanent deafness be caused ? 
Chapter III.—315. How does the sense of sight differ greatly 
from the other senses ? 316. What is light believed to be ? How rap- 
idly does it travel? Describe the wave theory of light. 3I7. How is 
the eye protected? 318. What is the shape of the eyeball? Its size? 
The three membranes ? Their situation and structure ? 319. What is 
the vitreous humor? What are miiscce volitantes (foot-note)? The 
crystalline lens ? The iris ? The aqueous humor ? 320. What is the 
use of the sclerotic coat ? Of the cornea ? Of the choroid ? What 
is the cause of “ dazzling ” ? What peculiarity have the eyes of albi- 
nos (foot-note)? 321. What is the structure of the retina? What is 
the blind-spot ? How may its existence be demonstrated ? Why does 
it not interfere with sight? 322. What is the use of the lens? 323. 
What change takes place in the eye to enable us to see either near or 
far objects at will ? How is this change produced ? What is the ciliary 
muscle ? Its function ? 324. What is the inner limit of distinct vision ? 
The farther limit? (In healthy eyes it is practically infinitely distant.) 
325. What causes the color of the iris? What are the functions of the 
iris? What are spherical and chromatic aberration? How are they 
prevented by the iris ? 326. How is it shown that the optic nerve con- 
veys only the sensation of light? 327. Illustrate the persistence of im- 
pressions on the retina. 328. What is meant by “color-blindness”? 
329. Explain near-sightedness and far-sightedness. 330. How is the 
eyeball moved? 331. What are the uses of the eyelids, eyebrows, and 
eyelashes? 332. What are the tears? Where do they come from, 
what is their use, and what becomes of them ? How is weeping ex- 
plained ? How are the tears prevented from overflowing on to the 
cheeks ? 333. What is said of the care of the eyes ? Of their deli- 
cacy ? Why is it bad to strain them ? Why should they not be opened 
under cold water (foot-note) ? What abuses of the eye should especial- 
ly be avoided ? 
PART VII. 
334- What is the larynx? Its structure, situation, and shape? 
335. What are the vocal chords? How are they moved (foot-note)? 
336. How is the voice produced? How is it modulated? 337. How 
is the larynx commonly abused ? What effect has inflammation of the 
vocal chords upon the voice ? How is “ breaking ” of the voice pro- 
duced ? 338. Why is rest necessary when the vocal chords are in- 
flamed ? 320 
QUESTIONS. 
PART VIII. 
339- How is alcohol produced? What is the percentage of alco- 
hol in distilled liquors ? In wines? In cider? In ales? In lager- 
bier? (foot-note). 340. What are the properties of alcohol? Its 
composition? How would it be classed as a food? 341. How does 
alcohol affect growing cells? 342. Is alcohol ever a food? Is it ever 
a poison ? Are any other poisonous substances used for food ? (foot- 
note). 343. Does all of the alcohol taken into the body pass out of it 
unchanged? What is supposed to become of it? How does it affect 
nutrition ? 344. Is alcohol a tissue-building food ? Why may it be 
called a supplementary food ? 345. What other matters besides alco- 
hol and water are contained in wine and beer? 346. How much alco- 
hol can be used daily without injury ? How is this ascertained ? 347. 
What general effects are produced by the excessive use of alcohol? 
348. What are the effects of pure alcohol upon the stomach ? 349. Of 
diluted alcohol ? Does it interfere with digestion ? 350. Effect of an 
intoxicating dose of alcohol upon the stomach? 351. Of the habitual 
excessive use? 352. Effect of alcohol upon the liver? How is cirrho- 
sis produced? 353. Effect of alcohol on the blood? 354. On the 
throat? 355. On the function of the lungs ? On the lungs themselves? 
Does pure alcohol taint the breath? (foot-note). 356. Effect of 
alcohol upon the heart ? How may this effect be utilized ? How is a 
fatty heart produced by it? 357. Effect of alcohol upon the blood- 
vessels? 358. What diseases of the vessels are produced by it? What 
is aneurism? 359. What permanent change in the features may be 
produced by alcohol? 360. Effect of a moderate dose of alcohol upon 
the nervous system? 361. Of a larger dose? How is double vision 
produced? 362. Effect of very large doses? After-effects? 363. How 
is alcohol supposed to cause these results? 364. What is chronic alco- 
holism? Its symptoms? 365. How is delirium tremens caused ? Its 
symptoms ? How may it end ? 366. Effect of alcohol upon the moral 
nature? 367. Effect of alcohol on nervous tissue? 368. Does alcohol 
increase or diminish the power of endurance ? Explain its effect in 
extreme cold and heat. 369. What poisonous substances besides alco- 
hol are found in alcoholic drinks ? Their effect upon the body ? 370. 
Why is alcohol used as a beverage? 371. What is opium? Morphia? 
Laudanum? Paregoric? (foot-note). How does opium sometimes 
seem to act as a food? Is it ever a food? 372. How does opium 
differ in its effects on the old and young? 373. Effect of opium on the 
stomach? Of morphia? What bad effect may follow the injection of 
morphia under the skin ? (foot-note), 374. Effect of opium on the QUESTIONS. 
321 
function of the lungs? On the bodily secretions ? 375. What marked 
difference in the effects of alcohol and opium? 376. Effect of a small 
dose of opium ? 377. Of a larger dose ? 378. Of a poisonous dose ? 
379. How is the opium-habit formed? 380. Effect of opium on the 
mental, moral, and physical nature? 381. Effect of the chloroform- 
habit? 382. Of the chloral-habit? 383. Explain the cause of the 
craving due to the habitual use of narcotics. 384. W'hat are the pres- 
ent teachings of science regarding stimulants and narcotics? GLOSSARY. 
Abdo'men. That portion of the trunk of the body which is situated 
between the diaphragm and the pelvis. The tissues surrounding 
and inclosing it, the muscles, skin, bones, etc., are called the ab- 
dominal walls. 
Accommodation. The adjustment of the internal parts of the eye in 
correspondence with the varying distance of external objects, so 
that their images always fall upon the retina. 
Albino. (Portuguese, from Latin, albas, white.) An animal in which 
pigment-cells are lacking, so that the hair and skin are white, and 
the pupil of the eye red. 
Albu'men. (A Latin word, signifying the white of an egg, which is 
almost pure albumen.) A very nutritious substance of very complex 
chemical composition, constituting a large part of meats and some 
vegetables, and classed with the nitrogenous foods or proteids (q. v.). 
Alcohol. (From the Arabic.) The common name of what chemists 
call ethyl-alcohol. Produced, together with carbon dioxide, by the 
fermentation of liquids containing sugar. Is present in all fer- 
mented fluids, the distilled liquors containing from 50 to 60 per 
centheavy wines, port, sherry, etc., 16 to 25 per cent; clarets 
and hocks, 7 to 16 per cent; and malt liquors, 2 to 10 per cent. 
Alimentary Canal. The long tube extending from the mouth down- 
ward through the body, by which food is received, digested, ab- 
sorbed, and the residue expelled. It includes the mouth, pharynx, 
oesophagus, stomach, small intestine, and large intestine. 
Anatomical Element. A portion of a living body so small that it can 
not be further divided without the destruction of its organization. 
Anatomy. (Greek, a cutting up.) The science that describes 
the appearance, structure, and situation of the different parts of the 
body. 
Aor'ta. (Greek, aoprr].) The large artery which first receives the 
blood from the left ventricle of the heart. 324 
GLOSSARY. 
Apoplexy. (Greek, cnron\r)tfa, a sudden stroke.) The escape of blood 
from a broken blood-vessel into the substance of the brain. 
Apparatus. A number of organs, differing in size and structure, which 
work together for the accomplishment of a particular object, e. g., 
the digestive apparatus, comprising the stomach, liver, pancreas, 
intestines, etc. 
Appen dix Vermifor'mis. (Latin, meaning the •worm-likeappendage?) 
A small projection from the caecum (q. v.), about six inches long 
and half an inch wide, of the same general structure as the intes- 
tine, situated in the right groin, and of no apparent use. Small ob- 
jects, such as cherry-pits, grape-seeds, etc., sometimes lodge in it, 
and give rise to a fatal inflammation. 
A'queous Hu'mor. (Latin, aqua, water.) A fluid in the eye lying 
between the crystalline lens and the cornea, consisting almost en- 
tirely of water, with a little salt. 
Ar'tery. (Greek, apTripia, from arjp, air, and rr)pciv, to contain, because, 
being always found empty after death, they were supposed to contain 
air during life.) A blood-vessel carrying blood away from the heart. 
Asphyx'ia. (Greek, curtpvtla, pulselessness.) Suffocation. 
Asth'ma. (Greek, aadpa, a gasping or panting.) A spasmodic affec- 
tion of the lungs, in which the caliber of the small bronchial tubes 
is diminished so much as to interfere with free respiration. 
Au'ditory Nerve. The nerve of hearing. 
Au ricles. (Latin, auris, the ear ; called auricles from their fancied 
resemblance to ears.) Two cavities of the heart into which the 
blood first enters as it returns from the rest of the body. 
Axis-Cylinder. A transparent or finely granular thread running in 
the center of every nerve-fiber, and believed to be the part along 
which the nerve-current passes. 
Bacte ria. (Greek, \BcucTripiov, a staff.) Small organisms, only visible 
under the microscope, shaped like rods, and believed to be the 
cause of many diseases. 
Bi ceps. (Latin, biceps, two-headed.) The large muscle extending on 
the front of the arm from the shoulder to the elbow. So called be- 
cause it is attached to two different points of the shoulder, i. e , by 
two heads. 
Blood-Corpuscles. The microscopic bodies which float in vast num- 
bers in the blood, and are the most essential constituent of it. 
Brach'ial. (Latin, brachium, the arm.) Pertaining to the upper arm, 
as the brachial artery. 
Bron chi. (Latin.) The tubes into which the trachea or windpipe 
is divided, and which convey air to the interior of the lungs. GLOSSAR V. 
325 
Bronchi'tis. Inflammation of the mucous membrane lining the 
bronchi. 
Cae'cum. (Latin, ccecus, blind.) The beginning of the large intestine. 
So called because it bulges downward from the point where the small 
intestine enters it, and forms a sort of cul-de-sac, or blind pouch. 
Cap illaries. (Latin, capillus, a hair.) The microscopic blood-ves- 
sels through which the blood passes from the arteries to the veins. 
Carbon Dioxide. Often called carbonic acid. A gas containing one 
part of carbon to two of oxygen. When inhaled it produces insen- 
sibility, followed by death if the inhalation is continued. 
Carbona'ceous Foods. Foods containing a large proportion of car- 
bon but no nitrogen. They also contain hydrogen and oxygen ; 
and, if the latter constituents are in the same proportion as in water, 
e. g., in starches and sugars, the foods are called carbohydrates; 
otherwise, hydrocarbons, e. g., the oils and other fats. 
Car'diac Orifice. (Greek, KapSia, the heart.) That opening of the 
stomach by which food enters. So called because it is nearest the 
heart. 
Carot'id Arteries. (Greek, Kapur'iSes, same meaning.) The large 
arteries supplying the front of the head and face. 
Cartilage. (Latin, cartilago, same meaning.) A bluish-white, elastic 
substance, found in various situations in the body, but especially 
covering the ends of bones which form joints. 
Ca'sein. (Latin, caseus, a cheese.) A nitrogenous substance or pro- 
teid (q. v.), forming the chief part of the curd of milk, often pressed 
into cheese. 
Catarrh. (Greek, Kardppoos, a morbid discharge.) An acute or 
chronic inflammation of a mucous membrane, usually attended by 
an increased secretion of mucus. 
Cau'da Equi'na. (Latin, meaning a horse's tail) The lower end of 
the spinal cord, so called because it is split up into strings of nerves 
resembling somewhat a tassel or a horse’s tail. 
Cerebellum. (Latin, signifying a little brain) A portion of the 
brain, constituting a distinct ganglion, situated under the posterior 
part of the cerebrum. 
Cer'ebro-spinal System. The brain and spinal cord, with the nerves 
arising from them. 
Cer'ebrum. (Latin, meaning the brain) The larger and upper part 
of the nervous mass lying within the skull, and conceded to be the 
seat of the intellect. 
Chlo'ral. A narcotic poison, formed from chlorine and alcohol. Used 
internally to produce sleep. 326 
GLOSSARY. 
Chloroform. A narcotic poison produced by the distillation of chloride 
of lime and alcohol, and generally used by inhalation. It produces 
anaesthesia, with complete unconsciousness, and is therefore useful 
in surgical operations. 
Cho'roid Coat. (Greek, x°P^0l/> leather, because of its dark, leather- 
like color.) The middle coat of the eye, containing numerous pig- 
ment-cells and blood-vessels. 
Chromat'ic Aberration. (Greek, xp»jua, color.) The splitting up of 
white light into colored light as it passes through a lens, in conse- 
quence of the difference in the refrangibility of its components. 
The image produced in the focus of such a lens will be fringed 
with color. The violet rays, being the most rapid in their undula- 
tions, are brought to a focus first, and the red rays, being the slow- 
est, last, so that if a screen be placed in the focus of the violet rays, 
when a lens is not achromatic, the image will be fringed by red rays, 
which have not yet converged to a focus ; and if the screen be put 
in the focus of the red rays, the image will be fringed by violet i-ays, 
which have passed their focus, and begun to diverge. 
Chyle. (Greek, gi/Axfc, same meaning.) The whitish fluid that is ab- 
sorbed from the intestine into the lacteals. 
Chyme. (Greek, xuM<k> juice.) The grayish, pulpy fluid into which 
food is converted in the stomach. 
Cil ia. (Latin, cilium, an eyelash.) Hair-like projections on the free 
extremity of certain epithelial cells. 
Cil'iary Muscle. A small, circular muscle in the interior of the eye- 
ball, which assists in the function of accommodation. 
Ciliated Epithelium. Epithelium having cilia on the free extremi- 
ties of the cells. 
Coch'lea. (Greek, a spiral shell.) A portion of the internal 
ear, shaped like the intex-ior of a snail-shell. 
Com'press. A pad or bandage applied directly to a wound, in order 
to compress it. 
Connective Tissue. A delicate lace-work of fibrous threads which 
extends through all organs of the body, binding their elements to- 
gether. 
Convolutions of the Brain. The projections on the surface of the 
brain, which look somewhat like those of a walnut-meat. 
Co-ordination. The bringing of several different things into such 
relations with one another that they perform their functions in har- 
mony. 
Cor nea. (Latin, cor nu, a horn.) The transparent portion of the ex- 
ternal coat of the eye. GLOSSARY. 
327 
Crystalline Lens. The lens of the eye, by which light is brought to 
a focus on the retina. 
Cutis. (Latin, meaning the skin!) The true skin, containing the hair- 
bulbs, blood-vessels, nerves, etc. The hard, insensitive layer out- 
side of the cutis is called the cuticle, i. e., the little skin. 
Cysticer'cus Cellulo'sae. (Part Latin and part Greek, kvcttis, a blad- 
der, KepKos, a tail, and cellula, meaning the bladder-tailed animal of 
the cellular [or connective] tissue.) A parasite, found in measly 
pork. When eaten by a human being, it is developed into a tape- 
worm in the intestine. 
Der ma. (Greek, Seppa, the skin.) Same as cutis (q. v.). 
Diaphragm. (Greek, Stacppaypa, a partition.) The muscular partition 
which separates the thorax, or chest, above, from the abdomen below. 
Disinfectants. Drugs which destroy the germs or particles of living 
matter that are believed to be the causes of various diseases. 
Dislocation. The displacement of the end of a bone. 
Drum of Ear. The membrane which separates the middle ear from 
the external ear, and on which the air-waves (sound-waves) first 
strike. 
Duode num. (Latin, duodeni, twelve each.) The first eight or ten 
inches of the small intestine nearest the stomach. So called be- 
cause its length is about twelve fingers’ breadth. It differs some- 
what in structure from the remainder of the intestines, and is a little 
larger. 
Epider'mal Cells. The cells composing the epidermis. 
Epider'mis. (Greek, inl, upon, and Sepua, the skin.) The same as 
cuticle (q. v.). 
Epiglot'tis. (Greek, iiri, upon, and y\a>Trls, the glottis.) A leaf- 
shaped cartilage, covered with mucous membrane, situated at the 
base of the tongue, just above the glottis. 
Epithelium. (Greek, M, upon, and 6r\\rj, a nipple.) A general term 
applied to various kinds of cells which cover all the free surfaces of 
the body, and are called epithelial cells. 
Ether. (Greek, alO'fip, the pure upper air.) A narcotic poison, made 
by distilling sulphuric acid with alcohol, and used as an anaesthetic 
in surgical operations. 
Ether, The. A very subtile form of matter, which is supposed to 
fill all space, permeating all bodies, to the vibrations of which the 
phenomena of light and heat, electricity and magnetism, are believed 
to be due. 
Eusta'chian Tube. (From Eustachi, its discoverer.) The tube or 
canal leading from the middle ear to the throat. 328 
GLOSSAR V. 
External Auditory Canal. The canal or tube leading from the ex- 
ternal ear inward to the drum. 
Facial Nerve. The motor nerve of the face. 
Fem'oral Artery. (Latin, femur, the thigh.) The main artery of the 
thigh. 
Fiber. A slender, microscopic thread of nitrogenous matter, very 
strong, tough, and elastic. When these threads are delicate, and 
loosely woven, they form connective tissue. When larger and more 
closely woven, and with a tendency to a longitudinal arrangement, 
they make fibrous tissue. There are other differences between 
these tissues, but they are too technical for insertion here. 
Fi brin. A nitrogenous material contained in the flesh of animals, and 
classed among the proteids. It is also produced by the coagulation 
of blood, constituting the greater portion of the clot. 
Fol'licles. (Latin, folliculus, a little sack or pouch.) A name applied 
to little pits or depressions in the skin or mucous membrane, out 
of which is poured a secretion, differing in different situations. 
Frontal Si nuses. Cavities in the bones of the skull, just over the 
eyebrows, the front wall causing the projection noticeable there. 
Function. (Latin, functio, from fungor, to perform.) The work per- 
formed by any organ of the body is called its function. 
Ganglion. (Greek, yayyXiov, a tumor.) A name applied to certain 
masses of gray nerve-matter, which have independent functions, 
and are separated from other masses of gray matter by intervening 
white matter. 
Gangrene. (Greek, yayypMva, gangrene.) Death of a portion of the 
soft -parts of the body, while still attached to the living tissues. 
Generally caused by deprivation of blood. 
Gastric. (Greek, yaar-fip, the belly.) Pertaining to the stomach. 
Gland. (Latin, glans, an acorn.) An organ which separates some- 
thing from or adds something to the blood that passes through it, 
by its own activity. 
Giot'tis. (Greek, yKurrls, the glottis.) The upper opening of the 
larynx. 
Glucose. (Greek, y\vKvs, sweet.) A kind of sugar, also called grape- 
sugar, found in fruits in considerable quantity. Produced artifi- 
cially by the action of a mineral acid on starch. Cane-sugar is con- 
verted into glucose in the stomach. 
Graduated Compress. Several pads of soft material, of different 
sizes, placed upon each other with the smallest underneath and the 
largest on top. U sed for compression of wounds. 
Granular Matter. Microscopic particles of matter, generally of a GLOSSAR Y. 
329 
nitrogenous nature, found in great quantity in certain tissues in 
the form of fine granules, whose precise character and function are 
not yet determined. 
Gray matter. The ash-colored portion of the nervous system, con- 
sisting mainly of nerve-cells, and believed to originate nerve-force. 
Great Pouch of the Stomach. The enlargement of the stomach 
toward the left of the cardiac orifice. 
Haemoglobin. (Greek, aT/xa, blood, and Latin, globus, a sphere.) The 
coloring-matter of the blood, consisting of a proteid snbstance in 
combination with iron, and making up the greater part of the blood- 
corpuscles. 
Homol ogous Bones. Those bearing similar relations to adjacent 
parts, and having similar special functions. 
Hygiene. (Greek, vyieivbs, healthy.) The science which describes 
what is healthful and what is injurious to the body, and how health 
may be maintained. 
Insensible Perspiration. Perspiration which is too small in quantity 
to collect in drops, and is therefore not ordinarily perceived. 
Internal Ear. That part of the ear which lies imbedded in bone, 
and in which the branches of the nerve of hearing are dis- 
tributed. 
Involuntary Muscles. Those that are not under the control of the 
will. 
Iris. (Greek, Tpis, a rainbow.) The colored muscular curtain in the 
front of the eyeball which surrounds the pupil; so called on ac- 
count of its variety of color. 
Jaundice. A disease, in which the coloring-matter of the bile is found 
in the blood and stains all the tissues yellow. 
Jug'ular Veins. (Latin, jugulum, the neck.) The large veins in 
the neck which return the blood from the head and face. 
Labyrinth. A portion of the internal ear, so called from its winding 
passages. 
Lach'rymal. (Latin, lachryma, a tear.) Pertaining to the tears, as 
the lachrymal gland, which secretes them. 
Lac'teals. (Latin, lac, lactis, milk.) Those vessels of the lymphatic 
system which absorb the chyle from the small intestine and appear 
like white threads and cords during digestion. 
Lar ynx. (Greek, \dpuy{, the larynx.) The organ of voice, situated at 
the top of the windpipe, producing the protuberance in the neck 
commonly known as Adam’s apple. 
Latis simus Dor’si. (Latin, meaning the broadest of the back.) A 
large, triangular muscle, attached throughout one side to the spine, 330 
GLOSSAR Y. 
and at the opposite angle to the arm near the shoulder, the fibers 
running from the spine to the arm. 
Lens. (Latin, lens, a lentil.) A transparent substance bounded by 
curved surfaces, so that light passing through it is refracted, i. e., 
bent out of its course. So called from its shape. 
Lig ament. (Latin, ligamentum, a band.) A closely knit mass of 
fibrous tissue, white, glistening, tough, and inelastic, which binds 
bones together at the joints. 
Lig'ature. (Latin, ligatura, a band.) A cord, used in surgery for 
tying blood-vessels, so as to prevent or stop bleeding. 
Lymph. (Latin,' lympha, water. IJfletic.) A yellowish, transparent, 
saltish fluid, found in the lymphatic vessels. 
Lymphat'ic Vessels. A system of tubes, varying in size, found in all 
parts of the body, like the blood-vessels, possessing great absorbent 
powers, containing always the lymph, which they collect and pour 
into the large veins near the heart. 
Lymphat'ic Glands. Small bodies, varying in size from a hemp-seed 
to an almond, scattered at intervals along the lymphatic vessels, 
which enter them and emerge again. Their functions are imper- 
fectly known. 
Marrow. The reddish, pulpy, fatty substance contained in the shaft 
of the long bones. 
Mas'seter Muscle. (Greek, a chewer.) A square muscle, 
attached to the skull and to the horizontal part of the lower jaw. 
Used in bringing the jaws together. 
Medul'la Oblonga ta. (Latin, meaning the pith or marrow lengthened 
out.) An enlargement at the upper extremity of the spinal cord, 
just as it enters the skull, but before its fibers diverge to the differ- 
ent parts of the brain. One of its chief functions is the control of 
respiration. 
Middle Ear. A small cavity, containing the minute bones which 
serve to conduct the sound-waves from the drum of the ear to the 
internal ear. 
Molec'ular. Pertaining to molecules, i. e., the smallest particles of 
matter into which any substance can be divided without becoming 
something else. 
Motor. Producing or giving rise to motion. A motor nerve is one 
whose function is to excite motion, instead of conveying sensation. 
Mucous Membrane. The soft, velvety membrane which lines all 
those cavities of the body which communicate with the external air. 
It is continuous with the skin, and secretes a glairy fluid, which 
keeps its surface constantly moist. GLOSS A R Y. 
331 
Mus'cae Volitan'tes. (Latin, meaning flitting flies.') Little strings or 
fibers, which float in the interior of the eye, and which can be 
readily seen by looking at a white wall, appearing like strings of 
beads, or transparent spheres clustered together, and moving when 
the eye moves. Found in healthy eyes. Spots which remain fixed 
imply disease. 
Myelin. (Greek, pve\6s, marrow.) The white nerve-matter which sur- 
rounds the axis-cylinder (q. v.), and forms the bulk of the nerve-fiber. 
Narcot ic Poisons. (Greek, vapKiu, to benumb.) Poisons such as 
opium, alcohol, ether, and chloroform, which produce at first, or in 
small quantity, a feeling of exhilaration, followed, if more be taken, 
by insensibility and death, or, if the person gets well, by a period 
of depression, from which the system is slow to recover. 
Nasal. (Latin, nasus, the nose.) Pertaining to the nose. 
Nerve-Center. A mass of gray nerve-substance, believed to originate 
the nerve-force. 
Nitrogenous Foods. Substances, chiefly of animal origin, which con- 
tain nitrogen, in addition to carbon, hydrogen, and oxygen. Many 
of them also contain a little sulphur. 
Non-nitrogenous. (See Carbonaceous.) 
Nucle'olus. Diminutive of nucleus. A small, bright particle of mat- 
ter inside of a nucleus, and forming a part of it. 
Nu'cleus. (Latin, nux, nucis, a nut.) A small body contained in the 
interior of a cell, and forming a part of it. 
Nystag'mus. (Greek, vucrraynds, a nodding.) An affection of the 
eye, in which the eyeball oscillates constantly from side to side. 
CEsoph'agus. (Greek, ohrotpayos, the gullet.) The tube, about nine 
inches long, that conveys substances from the throat to the stomach. 
Olfact'ory. (Latin, olfacio, to smell.) Pertaining to the sense of smell, 
as the olfactory nerve. 
Opium. A narcotic drug, obtained from the juice of the poppy. 
Optic. (Greek, otttikSs, belonging to sight.) Pertaining to the sense 
of sight, as the optic nerve. 
Orbit. The bony hollow in which the eyeball rests. 
Osmo sis. (Greek, uapis, a thrusting or pushing.) The passage of 
substances through animal membranes, and some other media, in 
consequence of an obscurely understood power of selection in the 
medium by which matters in solution and fluids are enabled to go 
through in one direction rather than another, and some substances 
to pass rather than others. By a skillful direction of this pro- 
cess, matters in solution may be separated from each other. Osmosis 
is constantly going on in the living body, and by its aid the nutri- GLOSSARY. 
332 
tive processes are carried on. The passage of matter through a mem- 
braneinto a vessel is called endosmosis, and the passage out,exosmosis. 
Ossification. (Latin, ossijicatio, from os, a bone, and facio, I make.) 
The change of any substance into bone. 
Oxida tion. The chemical union of oxygen with any substance, 
forming an oxide ; e. g., combustion is a rapid union of carbon and 
oxygen, forming carbon dioxide. 
Oxyhaemoglo'bin. (First part of the word oxygen, and haemoglobin, 
q. v.) Haemoglobin loosely combined with oxygen. 
Pan creas. (Greek, irayxpeas, the sweet-bread, from irav, all, and xpeas, 
flesh.) The organ whose secretion, called the pancreatic juice, di- 
gests fatty matters. Known to butchers as the sweet-bread. 
Papil'la. (Latin, papilla, a nipple.) A minute projection from the 
outer surface of the derma, containing the terminations of nerves 
and blood-vessels. 
Paraple gia. (Greek, irapair\-riyla, paralysis.) Paralysis of the lower 
part of the body on both sides. 
Par asite. (Greek, irapitriTos, a table-companion.) Any living thing, 
animal or vegetable, whose nature it is to attach itself to some other 
living thing, and derive its nourishment from it. 
Parot'id Glands. (Greek, irapwrldes, the parotid glands, from irapd, 
beside, and ovs, the ear.) The large salivary glands situated just 
in front of the ears. 
Pepsin. (Greek, ire-rruo, to cook.) The organic constituent of the 
. gastric juice, one of the main agents in digestion. 
Pericar'dium. (Greek, irepl, around, and xapSla, the heart.) The 
serous envelope of the heart. 
Perios'teum. (Greek, irepl, around, and oarreov, a bone.) The mem- 
brane, tough and fibrous, which envelops and clings closely to bone. 
Peritonae'um. (Greek, trepirivaiov, the peritonaeum, from irepl, around, 
and reiVw, to stretch.) The serous membrane which lines the ab- 
dominal walls and envelops the organs contained in the cavity of 
the abdomen. 
Phantom Limbs. A term applied by medical men to the sensory 
images produced by certain changes in the stumps of amputated 
limbs, which are of such a nature that the persons appear to them- 
selves to feel pain, tingling, or other sensations in that part of the 
limb which has been separated from the body. 
Phar ynx. (Greek, <papvy£, the throat.) That part of the throat which 
can be seen through the open mouth, without the aid of instruments. 
Physiol'ogy. The science that describes the functions of the differ- 
ent parts of living beings. GLOSSARY. 
333 
Pigment-Cells. (Latin, pigmentum, paint.) Cells naturally contain- 
ing coloring matter. 
Plas'ma. (Greek, -n-Xatr/xa, formed matter.) The fluid portion of the 
blood before coagulation. 
Pleu'ra. (Greek, irAevpa, the pleura.) The serous membrane which 
lines the chest and envelops the lungs. 
Por'tal Vein. (Latin, porta, a gate.) The large vein which carries 
the blood from the digestive organs to the liver. 
Pro'teids. (Greek, irpuros, first.) A class of substances, e. g., albu- 
men, fibrin, casein, etc., which contain carbon, hydrogen, oxygen, 
nitrogen, and sulphur, whose molecules are very complex, and 
which coagulate under proper conditions. So called because they 
form the basis and the greater part of animal bodies. 
Pro toplasm. (Greek, irpcoros, first, and wA.dafia, formed matter.) An 
albuminous, somewhat jelly-like substance, which forms the princi- 
pal part of living beings. It is very complex in structure, combin- 
ing several of the proteids, probably with carbohydrates and fats. It 
is the only matter in the world that presents the phenomena of life. 
Pul'monary. (Latin,piilmo, a lung.) Pertaining to a lung. 
Pulmonary Artery. The blood-vessel that conveys blood from the 
heart to the lungs. 
Pulmonary Lobules. The smallest independent divisions of the 
lungs, situated at the ends of the smallest bronchial tubes. 
Pulmonary Veins. The blood-vessels that convey blood from the 
lungs to the heart. 
Pulmonary Vesicles. The minute subdivisions of the pulmonary 
lobules. 
Pulse. The blow given by an artery when suddenly distended. 
Generally felt with the finger on the radial side of the wrist. 
Pupil. The circular hole in the iris through which light enters the eye. 
Pylo'rus. (Greek, irvAoopis, a gate-keeper.) The opening by which 
food passes from the stomach into the intestine. Also called the 
pylor ic orifice. 
Ra'dial Artery. The artery lying on the radial or thumb side of the 
fore-arm. 
Reflex Action. Motor action of a nerve-center in response to a stim- 
ulus without the co-operation of consciousness. 
Ret'ina. (Latin, retina, the retina, from rete, a net, from the net-like 
or mesh-like expansion of the optic nerve.) The internal nervous 
coat of the eye, on which images of external objects must be formed 
in order to make sight possible. 
Rods and Cones. A term applied, on account of their shape, to cer- 334 
GLOSSAR Y. 
tain nervous structures in the outer layer of the retina farthest from 
the light. They are packed side by side, like the seeds of a sun- 
flower, and are believed to be the structures by which the ether- 
waves are converted into a nerve-current, which, on reaching the 
brain, gives us the sensation of light. 
Sali'va. (Latin.) The spit or spittle, composed of fluids secreted by 
the mouth. 
Sal'ivary Glands. The glands that secrete the saliva. 
Sarto rius. (Latin, sartor, a tailor.) A long, ribbon-like muscle ex- 
tending from the outer and upper part of the hip-bone to the leg, 
just below and on the inner side of the knee. When it contracts it 
raises the leg and turns it inward, as in crossing the legs. 
Sciat'ic Nerve. (Contracted from ischiatic, Greek, l<rx‘ds, pain in 
the leg.) The largest nerve of the lower limb, extending from the 
pelvis to the foot at the back of the leg. 
Sclerot ic Coat. (Greek, OK\rip6s, hard.) The outer coat of the eye, 
consisting of white fibrous tissue. The white of the eye. 
Seba'ceous Glands. (Latin, sebaceus, from sebum, tallow.) Certain 
glands in the skin, generally situated near the roots of hairs, secret- 
ing a whitish, fatty, tallow-like substance, which tends to keep the 
skin and hairs soft and pliable. 
Semicircular Canals. A part of the internal ear filled with fluid, 
and containing filaments of the auditory nerve. So called from 
their shape. 
Serous Membrane. A delicate kind of membrane secreting a small 
amount of fluid, and lining all cavities in the body which do not 
communicate with the external air, excepting the joints. 
Serum. That fluid which remains after the clot has been separated 
from coagulated blood. 
Sewer-Air. A mixture of gases formed by the decomposition of 
organic matters in sewers. Its most dangerous constituents are the 
particles of solid matter and the living microscopic organisms that 
float in it. 
Spher'ical Aberration. The unequal refraction of light by a lens, 
at different distances from its center, in consequence of which the 
rays are not brought to the same focus, and the image is blurred 
and indistinct. 
Spinal Canal. The long cavity inside the backbone, in which the 
spinal cord lies. 
Spinal Cord. The long mass of nerve-substance that lies inside the 
spine. 
Spinal Nerves. The nerves that take their origin from the spinal cord. GLOSSAR Y. 
335 
Spine. The backbone. 
Sprain. Rupture of a ligament, or of fibers thereof, by the sudden 
twisting of a joint. 
Stape'dius. (Latin, stapes, a stirrup.) A small muscle of the middle 
ear. So called because it is connected with the stapes, one of the 
bones of the ear. 
Stria'tion. (Latin, stria, lines or markings.) The parallel marking 
of voluntary muscular fibers at right angles to their length, only to 
be seen with the microscope. 
Styp'tics. (Greek, <ttvtttik6s, astringent.) Substances that produce 
shrinking or contraction of living tissues. Astringents. 
Su'tures. (Latin, sutura, a seam.) The joints between the jagged 
edges of the bones of the skull, which appear as if dove-tailed. 
Sympathetic System. That portion of the nervous system that con- 
trols the functions of organic life, i. e., the functions that are or 
should be performed unconsciously. 
Syno'vial Membrane. (Greek, aw, with, and Latin, ovutn, an egg.) 
The membrane which lines the joints. So called because its 
secretion, the synovial fluid, resembles the white of an egg. 
System. Several different organs, of similar structure, spread through- 
out the body, and performing similar functions. 
Tape-worm. A worm whose larvae are introduced with the food, and 
developed in the intestine. It is composed of many segments at- 
tached to each other, and may grow to an enormous length, twenty 
or thirty feet. 
Tendons. The fibrous cords by which the muscles are united with 
the bones. 
Thorac'ic Duct. The tube which collects the lymph from the lacteals 
and most of the other lymphatic vessels, and discharges it into the 
veins near the heart. 
Tho rax. (Greek, 0c£pa£, the chest.) The part of the trunk situated 
above the diaphragm. The chest. 
Tissue. Two or more anatomical elements united so as to form one 
structure. 
Tra'chea. (Greek, rpaxeta, rough.) The windpipe. 
Trichi'na Spira'lis. (Greek, rplxwos, made of hair, and Latin, 
spiralis, spiral.) A parasitic worm often found in the flesh of the 
hog, and sometimes introduced with raw ham or pork into the 
human body, where it produces serious and even fatal disease. So 
called because it is slender in form, and is usually seen coiled up 
in a spiral. 
Trigem'inal Nerve. (Latin, trigemini, three of a kind.) The nerve 336 
GLOSSARY. 
of sensation of the face. So called because there are three large 
branches of it. 
Tuber'cular Quadrigem'ina. (Latin, tubercula, small swellings, and 
quadngemina, four of a kind.) Certain protuberances, four in 
number, near the base of the brain—the nerve-centers of vision. 
Tym'panum. (Greek, rv/xiravor, a drum, or Latin, tympanum.) The 
cavity of the middle ear. 
Ulnar Artery. The artery lying on the inner or little-finger side of 
the fore-arm. 
U rea. An excrementitious substance expelled from the body through 
the kidneys. 
Vaso-motor Nerves. (Latin, vasa, vessels.) Nerves which control 
the movements of the muscles lying in the walls of the blood- 
vessels. 
Veins. Blood-vessels which convey blood toward the heart. 
Ven'ae Ca'vae. (Latin, meaning the holloxv veins.) The large veins 
which collect blood from the smaller ones and discharge it into the 
heart. 
Ven'tricles. (Latin, ventriculus, a little stomach.) The two largest 
cavities of the heart, from which the blood is sent out into the 
arteries. 
Ver tebra. (Latin, vertebra, a vertebra,'from verto, I turn.) One of 
the smaller bones of which the spine is composed. 
Ver'tebral Arteries. Arteries which pass up into the head through 
the vertebrae of the neck. 
Vestibule. A part of the internal ear. 
Vil li. (Latin, meaning closely-set hairs.) Minute projections from 
the internal surface of the small intestine, containing blood-vessels 
and lacteals, by which the nutritious portions of the food are ab- 
sorbed. 
Vital Knot. A portion of the medulla oblongata (q. v.), the destruc- 
tion of which kills instantly. 
Vit reous Humor. (Latin, vitreus, glassy.) A transparent, jelly-like 
mass filling the space in the eyeball between the lens and the retina. 
Vocal Chords. Two pearly-white, glistening, fibrous bands at the 
upper part of the larynx, whose vibration causes the voice. The 
opening between them is the glottis (q. v.). 
Voluntary Muscles. Muscles that are under control of the will. 
White Matter. A kind of nervous tissue composed mainly of fibers, 
and serving to conduct nerve-force, but not to originate it. INDEX. 
Abercrombie, 198. 
Aberration, chromatic, 265. 
spherical, 265, 
Absinthe, 295. 
Abuse of nervous system, 216. 
Accommodation, function of, 262. 
Adam’s apple, 272. 
Air, amount respired with each 
breath, 107. 
amount respired daily, 109. 
changed by respiration, no. 
composition of, no, 113. 
contamination of, 114, 115. 
impure, in houses, 115. 
purification of, by plants, 114. 
watery vapor in, 113. 
Albinos, eyes of, 259. 
Albumen of blood, 95. 
of food, 17. 
Alcohol, diseases due to, 76, 283- 
288, 290-293. 
as a food, 279, 280. 
composition of, 278. 
effects of, 74, 278-289. 
effect of, on youth, 76, 278. 
endurance diminished by, 76, 
293. 294. 
Alcoholic beverages, 277, 280, 294, 
295. . 
moderate use of, 281. 
origin and properties of, 277. 
oxidation of, 279. 
Alimentary canal, 57. 
muscles of, 59. 
Anatomical element defined, I. 
Anatomy defined, 1. 
Aneurism, 288. 
Animal heat, 223. 
cause of, 225. 
theories of, 224. 
Anterior nerve-root, division of, 
187. 
Aorta, 130, 145. 
Apoplexy, igo. 
Apparatus defined, 2. 
Appendix vermiformis, 80. 
Aqueous humor, 258. 
Aroma, 241. 
Arteries, 120. 
compression of large, 161. 
rapidity of current in, 142. 
structure of, 136. 
behavior of, when cut, 155. 
Artery, brachial, 147. 
carotid, 147. 
femoral, 146. 
formation of clot in, 158. 
pulmonary, 130, 149. 
radial, I.; 7. 
ulnar, 147. 
venous blood in, 143. 
vertebral, 147. 
Artificial respiration, 122. 
Asphyxia, 120. 
Asthma, 104. 
Auditory nerve, 249. 
Auricles, 128. 
Automatic actions, 193. 
Axis-cylinder, 167. 
Bacteria, 118. 
Banting system, 47, 338 
INDEX. 
Bath, effect of cold, 231. 
warm, 232. 
Bathing, rules for, 232. 
Beaumont, 64. 
Bell, Sir Charles, 1S6. 
Bernard, Claude, 55, 
Biceps, disadvantageous action of, 
34- 
Bile, 83. 
function of, 84, 85. 
Black-heads, 222. 
Bleeding. (See Haemorrhage.) 
Blind spot of eye, 260. 
Blood, 93. 
albumen of, 95. 
total amount of, 97. 
changes of, during digestion, 91. 
changes of, during respiration, 
nr. 
coagulation of, 96, 97, 154. 
distribution of, 145. 
fibrin of, 95 
oxygen in, 97. 
plasma of, 95. 
rapidity of, 142. 
serum of, 96. 
varying color of, 98, 112. 
Blood-corpuscles, function of, 112. 
red, 93. 
white, 95. 
Blood-vessels, 136 
communicating, 141 
Blushing, 178. 
Body, effect of cold on, 226. 
effect of heat on, 227. 
minute structure of, 3. 
temperature of, 225. 
temperature of, how regulated, 
22S. 
Bone at different ages, 10. 
composition of, 9. 
minute structure of, 12. 
living and dead, 9. 
renewal of, 14. 
extremities and shaft of, 11. 
Bones, injuries of, 25. 
number of, 15. 
of ear, 248. 
ossification of, 15. 
uses of, 9. 
varieties of, 11. 
Brachial artery, 147. 
Brain, 194. 
convolutions of, 196. 
disease of, 200. 
hemispheres of, 196. 
importance of exercising, 2x3. 
injuries of, 199, 201. 
over-exercise of, 2x4. 
size of, 198. 
smaller ganglia of, 204. 
softening of, 200. 
Breath, organic matter of, ill, 
115- 
shortness of, 152, if'3, 206. 
Bronchi, too. 
Caecum, 80. 
Caffeine, 279; 
Callous skin, 223. 
Calvin Edson, 89. 
Capillaries, 137. 
pressure in, 141. 
rapidity of current in, 142. 
size of, 138. 
Carbon dioxide, theories about, 
no. 
where formed, 1x2. 
Carbonaceous foods, 45. 
Cardiac orifice of stomach, 62. 
Care of injured persons, 27. 
Carotid artery, 147. 
Cartilage, 23. 
Cartilages of trachea, 100. 
Casein, 47. 
Cauda equina, 183. 
Cell, 4- 4 
Cells, division of, 6. 
epidermal, 59. 
epithelial, 59. 
growth of, 6. 
living and dead, 5. 
nerve, 167. 
selection by, 5. 
size of, 5. 
vicarious action of, 8. 
Cerebellum, diseases of, 203. 
function of, 202. 
removal of pigeon’s, 202. 
size of, 202. 
structure of, 201. 
Cerebro-spinal system, 166. 
Cerebrum, 195. 
function of, 197, 201. INDEX. 
339 
Cerebrum, removal of pigeon’s, 199. 
size of, 198. 
structure of, 196. 
Chabert, 229. 
Chapped hands, 233. 
Chest, natural shape of, 21. 
Chloral, 75, 301. 
Chloroform, 75, 300. 
Choroid coat, 257. 
function of, 259. 
Chromatic aberration, 265. 
Chronic alcoholism, 291. 
Chyle, 90. 
Chyme, 79. 
Cilia, 103. 
action of, 108. 
Ciliary muscle, 262. 
Ciliated epithelium, 103. 
Circulation, 125, 130. 
disorders of, 150. 
general, 127. 
obstruction of, 150. 
pulmonary, 127. 
rapidity of, 144. 
Cirrhosis, 285. 
Clot, 96. 
Clothing, 235. 
Coagulation of blood, 96. 
conditions of, 154. 
Cochlea, 249. 
Coffee, 77. 
Cold arrests bleeding, 156. 
bath, effect of, 231. 
effect of, on body, 226. 
Colds, cause of, 181. 
in the head, danger of, 252. 
Color-blindness, 266. 
Combustion, pollution of air by, 
II5\ 
Complexion, 219. 
Compress, graduated, 162. 
Compression of wounds, 157. 
Condiments, 72. 
Confectionery, 77. 
Connective tissue, 29. 
Contagious diseases, 117. 
Convolutions of brain, 196. 
Cooking, 49. 
Co-ordination, organs of, 164. 
Cornea, function of, 259. 
structure of, 256. 
Corns, 223. 
Crying, 269. 
Crystalline lens, 258. 
function of, 261. 
Curvature of spine, 38. 
Cuticle, cutis, 217. 
Cuvier, 198. 
Cysticercus cellulosse, 78. 
Dandruff, 234. 
Deafness, frequent cause of, 253, 
Deception by the senses, 238. 
Delirium tremens, 292. 
Derma, 218. 
Diaphragm, 105. 
Diffusion of gases, 108. 
Digestion, blood during, 91. 
intestinal, 79. 
nervous control of, 180. 
stomach, 57, 63. 
time required for, 72, 
Digestive apparatus, 50. 
Disinfectants, 118. 
Dislocations, 26, 27. 
Dissipation, 216. 
Draughts, 116, 176, 180. 
Drink, 73. 
Dropsy, 151, 152. 
Drowned, resuscitation of the, 121. 
Drowning, 121. 
Drum of ear, 247. 
Duodenum, 81. 
Dupuytren, 198. 
Ear, bones of, 248. 
care of, 252. 
drum of, 247. 
external, 246. 
insects in, 252. 
internal, 249. 
middle, 247. 
muscles of, 247. 
-scoops, 252. 
Ear-wax, 252. 
Eating, rules for, 69-71, 78. 
Education, 211. 
Element, anatomical, 1. 
Emotion, effects of, 178. 
Epidermal cells, 59. 
Epidermis, 59,217, 219. 
Epiglottis, 102, 
Epithelium, 59. 
ciliated, 103. 340 
INDEX. 
Ether, 75. 
the, 254. 
Eustachian tube, 248. 
inflammation of, 253. 
Exercise, 39. 
of nervous system, 213, 214. 
rules for, 41. 
Exhaustion, danger of, 40. 
Expiration, force of, 107. 
mechanism of, 106. 
External auditory canal, 252. 
External ear, 246. 
Extremities, wounds of, 160. 
Eye, blind spot of, 260. 
situation of, 255. 
Eyeball, muscles of, 267. 
structure of, 255. 
Eyebrows, lashes, lids, 268. 
Eyes, care of, 270. 
opening of, under water, 271. 
straining of, 270. 
Face, washing of, 233. 
Facial nerve, 209. 
Fainting, 162. 
Far-sight, 267. 
Fat, 46. 
craving for, in winter, 226. 
Fatigue, 37. 
Femoral artery, 146. 
Fiber, 3. 
Fibrin of blood, 95. 
of food, 47. 
Fibrous tissue, 3. 
Fire-king, 299. 
Fireplace as ventilator, 116. 
Fluid, synovial, 24. 
Follicles, hair, 221. 
Food, absorption of, 86. 
carbonaceous, 45. 
choice of, 72. 
classification of, 43. 
daily amount of, 49. 
inorganic elements of, 45. 
necessity of, 43. 
nitrogenous, 47. 
non-nitrogenous, 45. 
parasites in, 78. 
variety of, 48. 
Fracture, green-sticli, II. 
results of, 26. 
Fractures, 25. 
Fractures, healing of, 27. 
Freezing, 225. 
Frog’s foot, circulation in, 142. 
Frontal sinuses, 20. 
Function defined, 2. 
Fusel-oil, 294. 
Ganglia, nervous, 168. 
sympathetic, 175. 
Gangrene, 154. 
Garotte, 207. 
Gases, diffusion of, 108. 
Gastric juice, amount of, 66. 
composition of, 66. 
secretion of, 65. 
General circulation, 127. 
Glands, lachrymal, 268. 
lymphatic, 88. 
nervous supply of, 178. 
salivary, 54. 
sebaceous, 221. 
sweat, 222. 
Glottis, 101, 272. 
Glucose, 46. 
Graduated compress, 162. 
Granular matter, 5. 
Gray matter, function of, 171. 
structure of, 167. 
Great pouch of stomach, 62. 
Green-stick fracture, 11. 
Gymnastics, 39. 
Habits, formation of, 212. 
Haemoglobin, 112. 
Haemorrhage, 155. 
artificial arrest of, 156. 
compression for, 157. 
natural arrest of, 155. 
permanent arrest of, 158. 
Hair, 220. 
cutting of, 225. 
Handkerchief, knotted, 161. 
Hands, chapping of, 233. 
washing of, 233. 
Hang-nails, 235. 
Hausmann, 198. 
Hearing, sense of, 246. 
Heart, 126. 
blood-vessels connected with, 
130. 
cavities of, 127. 
contraction of, 133. INDEX. 
341 
Heart, disease of, 151. 
rapidity of contraction of, 134. 
sounds of, 134. 
two sides of, 127. 
valves of, 128. 
voluntary arrest of, 135. 
Heart-disease, detection of, 154. 
Heat, effect of, on body, 227. 
exposure to dry, 229. 
exposure to moist, 229. 
Hemispheres of brain, 196. 
Hiccough, 106. 
Homologous bones, 23. 
Humor, aqueous, 258. 
vitreous, 257. 
Hunger, 70. 
Hygiene defined, 1. 
Impure air, 115. 
Inactivity, muscular, 38. 
Indigestion, 67. 
Injured persons, care of, 27. 
Injuries of bones and joints, 25. 
Inorganic elements of food, 45. 
Insects in the ear, 252. 
Insensible perspiration, 228. 
Inspiration, force of, 107. 
mechanism of, 105. 
Internal ear, 249. 
Intestinal digestion, 79. 
juices, 85. 
villi, 87. 
Intestine, large, 80. 
muscles of, 80. 
small, 79. 
Intoxication, 74, 289 
Involuntary muscles, 31. 
Iris, 258. 
color of, 264. 
function of, 265. 
nervous supply of, 177. 
Irritability, muscular, 35. 
Jaundice, 84. 
Joints, 23. 
injuries of, 26. 
Jugular veins, 148. 
juice, gastric, 65. 
intestinal, 85. 
pancreatic, 82. 
Knotted handkerchief, use of, 161 
Labyrinth, 249. 
Lachrymal gland, 268. 
Lacteals, 86, 88, 90. 
Large intestine, 80. 
Larynx, 100, 272. 
abuse of, 274. 
care of, 275. 
movable cartilages of, 273. 
Latissimus dorsi, 33. 
Laudanum, 296. 
Lavoisier, 224. 
Lead in candy, 78. 
Lens, 258. 
function of, 261. 
varying shape of, 263. 
Liebig, 224. 
Ligaments, 24. 
Ligatures, use of, 158. 
Light, 254. 
Limbs, number of bones in, 22. 
Limit of distinct vision, 263. 
Liver, 82. 
Liver-sugar, 82. 
Living skeleton, 89. 
Lungs, 102. 
blood-vessels of, 104. 
change of air in, 108. 
minute structure of, 103. 
serous membrane of, 104. 
Lymph, 88. 
Lymphatic glands, 88. 
Magendie, 186. 
Malarial fevers, 117. 
Marrow, 12. 
Masseter muscle, 53. 
Mastication, 50, 69. 
Medulla oblongata, 205. 
automatic action of, 206. 
Membrane, mucous, 57. 
serous, 60. 
synovial, 24. 
Microscopic organisms, 117, 118. 
Middle ear, 247. 
Minute structure of body, 3. 
Morphia, 296, 297. 
Mouth, watering of the, 55, 178. 
Mucous membrane, 57. 
Mumps, 54. 
Muscae volitantes, 257 
Muscle, ciliary, 262. 
minute structure of, 31. 342 
INDEX. 
Muscles, 29. 
contraction of, 32. 
of eyeball, 267. 
function of, 31. 
involuntary, 31. 
size of, 33. 
voluntary, 29. 
Muscular contraction, force of, 34, 
contraction, sound of, 53. 
contraction, waste during, 37. 
inactivity, 38. 
irritability, 35. 
overwork, 37. 
sense, 35, 36. 
strength, feats of, 40. 
Mustard, 73. 
Myelin, 167. 
Nails, 220. 
care of, 235. 
Narcotic poisons, 75, 301-305. 
Narcotism, symptoms of, 75. 
Nasal passages, 99. 
Near-sight, 267. 
Nerve, auditory, 249. 
division of anterior root of, 187. 
division of posterior root of, 188. 
effect of dividing, 185. 
facial, 209. 
olfactory, 243. 
optic, 260. 
sciatic, 210. 
trigeminal, 208. 
Nerve-cells, 167. 
Nerve-centers, 168. 
Nerve-current, nature of, 169, 172. 
rapidity of, 170. 
Nerve-fibers, 166. 
function of, 168, 169. 
Nerves, electrical current in, 169, 
172. _ 
exhaustion of, 171. 
sensations referred to extremity 
of, 190. 
structure of, 168. 
vaso-motor, 145, 179. 
Nervous system, abuse of, 216. 
divisions of, 164. 
education of, 211. 
Nervous tissue, 166. 
Nitrogenous foods, 47. 
Non-nitrogenous foods, 45. 
Nose, structure of, 99. 
Nucleolus, 5. 
Nucleus, 5. 
Nystagmus, 259. 
(Esophagus, 57, 60. 
Olfactory nerve, 243. 
Opium, 75, 296. 
effects of, 296-300. 
Optic nerve, 260. 
Optic nerves, origin of, 201. 
Orbit of eye, 255. 
Organ of speech, 272. 
Organic matter of breath, in, 115. 
Organisms, microscopic, 117, 118. 
Organs of co-ordination, 164. 
of motion, 9. 
of perception, 237. 
of protection, 217. 
! of repair, 42. 
Ossification of bones, 15. 
Out-door sports, 39. 
Overeating, 69. 
Over-exercisc of brain, 214. 
Overwork, muscular, 37. 
Oxygen, necessity of, 97. 
Cxyhcemoglobin, 112. * 
Pancreas, 81. 
functions of, 82. 
Pancreatic juice, 82. 
Papillae of skin, 219. 
structure of, 237. 
Paraplegia, 192. 
Parasites in food. 78. 
Paregoric, 296. 
Parotid glands, 54. 
Pepper, 72. 
Pepsin, 76. 
Perception, organs of, 237. 
Pericardium, 126. 
Periosteum, 12. 
uses of, 13. 
Peritonaeum, 86. 
Perspiration, amount of, 228. 
Perspiratory glands, 222. 
Phantom limbs, 191. 
Pharynx, 60. 
Physiology defined, 1. 
Pigeon, removal of cerebellum of, 
202. 
removal of cerebrum of, 199. INDEX. 
343 
Pigment-cells, 219. 
Plain food, advantages of, 71. 
Plants, respiration of, 114. 
Plasma, 95. 
Pleura, 105. 
Pleurisy, 105. 
Portal vein, 89, 148. 
Posterior nerve-root, division of, 
188. 
Protection, organs of, 217. 
Proteids, 47. 
Protoplasm, 4, 5. 
Proud flesh, 7. 
Pulmonary artery, 130, 149. 
circulation, 127. 
lobule, 103. 
veins, 130, 149. 
vesicle, 103. 
Pulse, cause of, 136. 
rapidity of, 135. 
situation of, 137. 
voluntary control of, 135. 
Pupil, contraction of, 176. 
Pylorus, 62. 
Radial artery, 147. 
Red blood-corpuscles, 93. 
Reflex action, 170, 191, 210. 
Respiration, 99. 
artificial, 122. 
Rest for muscles, 40. 
Resuscitation of the drowned, 121. 
Retina, 257. 
effect of shocks on, 265. 
persistence of impressions on, 
266. 
structure of, 260. 
Ribs, 20. 
cartilages of, 21. 
motion of, 21. 
Rods and cones of retina, 260. 
Roots of spinal nerves, 1S6. 
Rules for bathing, 232. 
for dress, 236. 
for eating, 78. 
for exercise, 41. 
for entering sick-room, 119. 
St. Martin, 64. 
Saliva, 54. 
amount of, 56. 
use of, 55. 
Salivary glands, 54. 
Salt, 44. 
Sartorius, 33. 
Savages, acute senses of, 244. 
Scalp, care of, 234. 
Schwann, white substance of, 167. 
Sciatic nerve, 210. 
Sclerotic coat, 255. 
function of, 259. 
Sebaceous glands, 221. 
Semicircular canals, 249-251. 
Sensation, 170. 
divisions of, 184. 
Sense, muscular 35. 
of hearing, 246. 
of sight, 254. 
of smell, 243. 
of taste, 240. 
of touch, 237. 
Senses, deception by, 238. 
Serous membrane, 60. 
Serum of blood, 96. 
Sewer-air, 119. 
Shoes, 236. 
Shortness of breath, 103, 152, 
206. 
Sick - room, rules on entering, 
119. 
Sight, sense of, 254. 
Sinuses, frontal, 20. 
Skin, absorption through, 230. 
effects of pressure on, 223. 
impurities on, 231. 
respiration through, 230. 
structure of, 217. 
Skull, 18, 19. 
Sleep, 214. 
Small intestine, 79. 
Smell, sense of, 243. 
use of, 52, 245. 
Sniffing, 244. 
Soap, 233, 234. 
Solar plexus, 175. 
Sound, determination of source of, 
250. 
qualities of, 250. 
Sounds of heart, 134. 
Special senses, 239. 
Speech, organ of, 272. 
Spherical aberration, 265. 
Spinal canal, 17. 
Spinal cord, 183. INDEX. 
344 
Spinal cord, crossing of fibers in, 
189. 
diseases of, 192. 
reflex action of, 191. 
Spinal nerves, 184. 
roots of, 186. 
two kinds of fibers of, 189. 
Spine, 15. 
cartilages of, 15, 18. 
curvature of, 38. 
mobility of, 17. 
Spleen, 91. 
function of, 92. 
Splints, 28. 
Sprains, 27. 
Stapedius, 33. 
Starch, 45. 
Stomach, appearance of, during di- 
gestion, 67. 
foods digested in, 63. 
interior of, 65. 
movements of, 66. 
structure of, 60. 
Stomach-digestion, 57, 63. 
time of, 68. 
Strength, muscular, 40. 
Striation, 31. 
Styptics, 156. 
Suffocation, 120. 
Sugar, 46. 
Sunstroke, 226. 
Sutures, 19. 
Swallowing, 50, 60. 
Sweat-glands, 222. 
Sweet-bread, 81. 
Sympathetic ganglia, 175. 
Sympathetic nerves, division of, 
177. 
peculiarity of, 172. 
sluggish action of, 175. 
Sympathetic system, 166, 174. 
effect of cold on, 1S0. 
exhaustion of, 181. 
Synovial fluid, 24. 
membrane, 24. 
System defined, 2. 
Tape-worm, 78. 
Taste, modifications of, 240. 
peculiarities of, 241. 
sense of, 239, 240. 
use of, in eating, 52. 
Tea, 77. 
Tears, 268. 
Teeth, 52. 
care of, 56. 
Temperature of body, 225. 
how regulated, 228. 
Tendons, 33. 
Theine, 279. 
Thoracic duct, 89. 
Tight lacing, effect of, 21. 
Tissue, connective, 29. 
defined, I. 
fibrous, 3. 
Tobacco, 77. 
Toilet-soaps, 234. 
Tongue, nerves of, 240. 
Touch, delicacy of, 238. 
sense of, 237. 
Townsend, Colonel, 135. 
Trachea, 100. 
Trichina spiralis, 78. 
Trigeminal nerve, 208. 
Tubercula quadrigemina, 204. 
Tympanum, 248. 
Ulnar artery, 147. 
nerve, 190. 
Urea, 42. 
Valves of heart, 128. 
of heart, peculiar, 131. 
of veins, 140. 
Vaso-motor nerves, 145, 179. 
Vein, arterial blood in, 143. 
behavior of, when cut, 155. 
portal, 89, 148. 
Veins, 120. 
circulation in, 139. 
jugular, 148. 
pulmonary, 130, 149. 
rapidity of current in, 143. 
structure of, 138. 
valves of, 140. 
Venae cavae, 130, 138, 148. 
Ventilation, 115. 
Ventricles, 128. 
Ventriloquism, 251. 
Vertebra, 15. 
Vertebral artery, 147. 
Vestibule, 249. 
Villi, 87. 
pumping action of, 90. INDEX. 
345 
Vision, limit of distinct, 263. 
Vital knot, 205, 207. 
Vitreous humor, 257. 
Vocal chords, 102, 272. 
congestion of, 274. 
Voice, breaking of, 275. 
modulation of, 274. 
production of, 273. 
Voluntary muscles, 29. 
Warm bath, effect of, 232. 
Waits, 223. 
Washing hands and face, 233. 
Waste during muscular contrac- 
tion, 37. 
Water, 44. 
paramount necessity of, 48. 
Wave theory of light, 254. 
Weeping, 269. 
White blood-corpuscles, 95. 
White matter, 1O6. 
function of, 169. 
Windpipe, 100. 
Wounds, compression of, 157. 
of extremities, 1C0. 
healing of, 7. 
THE END. APPLETONS’ 
SCIENCE TEXT-BOOKS. 
D. Appleton & Co. have the pleasure of announcing that in response to the 
growing interest in the study of the Natural Sciences, and a demand for improved 
text-books representing the more accurate phases of scientific knowledge, and 
the present active and widening field of investigation, they have made arrange- 
ments for the publication of a series of text-books to cover the whole field of 
science-study in High Schools, Academies, and all schools of similar grade. 
No abridgment of labor or expense has been permitted in the effort to make 
this series worthy to stand at I lie head of all educational publications of this kind. 
Although the various books have been projected with a view to a comprehensive 
and harmonious series, each volume will be wholly independent of the others, 
and complete in itself. 
NOW READY. 
THE ELEMENTS 07 CHEMISTRY. By Professor P. W. Clakke, 
Chemist of the United States Geological Survey. 12mo. Cloth, $1.40. 
THE ESSENTIALS OE ANATOMY, PHYSIOLOGY, AND HY- 
GIENE. By Roger S. Tract, M. D., Healih Inspector of the New York 
Board of Health ; author of “ Hand-Book of Sanitary Information for House- 
holders,” etc. 12mo. Cloth, $1.11 
A COMPEND OE GEOLOGY. By Joseph Le Conte, Professor of Geol- 
ogy and Natural History in the University of California; author of “Ele- 
ments of Geology,” etc. Cloth, $1.40. 
ELEMENTS OF ZOOLOGY. By C. P. Holder, Pellow of the New York 
Academy of Science, Corresponding Member Linnaean Society, etc.; and J. 
B. Holder, M. D., Curator of Zoology of American Museum of Natural 
History, Central Park, New York. Cloth, $1.40. 
DESCRIPTIVE BOTANY. A Practical Guide to the Classification of Plants, 
with a Popular Flora. By Eliza A. Youmans, author of “ The First Book 
of Botany,” editor of “Henslow’s Botanical Charts.” 12:uo. Cloth, $1.40. 
APPLIED GEOLOGY. A Treatise on the Industrial Re’ations of Geological 
Structure; and on the Nature, Occurrence, and Uses of Substances derived 
from Geological Sources. By Samuel G. Williams, Professor of General 
aDd Economic Geology in Cornell University. 12mo. Cloth, $1 40. 
Ollier volumes to follow as rapidly as they can he prepared. 
New York: D. APPLETON & CO., 1, 8, & 5 Bond Street SCIENCE. 
Huxley and Youmans’s Physiology and Hygiene. By 
Thomas H. Huxley, LL. D., F. R. S., and William J. Youmans, 
M. D. New and revised edition. With numerous Illustrations. 
12mo. 420 pages. 
Coming’s Class-Book of Physiology. With 24 Plates, and nu. 
merous Engravings on Wood. 12mo. 324 pages. 
Youmans’s Hand-Book of Household Science. A Popular 
Account of Heat, Light, Air, Aliment, and Cleansing, in their Sci- 
entific Principles and Domestic Applications. With numerous illus- 
trative Diagrams. 12mo. 470 pages. 
Physiography : An Introduction to the Study of Nature. By Thomas 
H. Huxley. With Illustrations and Colored Plates. 12mo. 
Nicholson’s Biology. Illustrated. 12mo. 163 pages. 
Nicholson’s Ancient Life-History of the Earth. A Compre- 
hensive Outline of the Principles and Leading Facts of Paleonto- 
logical Science. 12mo. 407 pages. 
Anthropology : An Introduction to the Study of Man and Civilization. 
By Edward B. Tylor, D. C. L., F. R. S. With 78 Illustrations. 
12mo. 448 pages. 
Science Primers. Edited by Professors Huxley, Roscoe, and Dal- 
four Stewart. 
Chemistry II. E, Roscoe. 
Physics Balfour Stewart. 
Physical Geography A. Geikie. 
Geology A. Geikie. 
Physiology M. Foster. 
Astronomy J. N. Lockter. 
Botany J. D. Hooker. 
Logic W. S. Jevons. 
Inventional Geometry W. G. Spencer. 
Pianoforte Franklin Taylor. 
Political Economy W. S. Jevons. 
Natural Resources of the United States J. Harris PattOn. 
Scientific Agriculture N. T. Lupton1. 
D. APPLETON & 00., Publishers, 
NEW YORK, BOSTON, CHICAGO, SAN FRANCISCO.