LESSONS IN PHYSIOLOGY 
FOR USE IN SCHOOLS 
INCLUDING 
ANATOMY, PHYSIOLOGY, AND HYGIENE 
AND 
THE EFFECTS OF ALCOHOL AND OTHER STIMULANTS ON 
THE HUMAN BODY AND MIND 
BY 
GEORGE D. LIND, M.D. 
Member of St. Louis Academy of Science; Author of “Man,” etc. 
DANVILLE, INDIANA 
INDIANA PUBLISHING COMPANY 
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g 
Copyright, 1891, 
By JONATHAN RIUDON. 
Typography by J. S. Cushing & Co., Boston. 
Presswork by Berwick & Ssiith, Boston. AUTHOR’S PREFACE. 
The writer of this volume has endeavored to present the leading 
facts and principles of Anatomy, Physiology, and Hygiene in the 
simplest and briefest manner consistent with the great scope of 
these subjects. While the book may contain more Anatomy than 
books of its kind usually do, the writer justifies it on the ground 
that no thorough knowledge of Physiology and Hygiene can be had 
without a considerable amount of detail in Anatomy, which is the 
fundamental science. The main physiological facts and principles 
and good working rules of Hygiene, however, are also given, and in 
such a manner that the teacher can enlarge upon them if necessary. 
Technical language as far as possible has been avoided. Nearly 
all words which may be new to the pupil are either defined in the 
text or in the glossary which is combined with the alphabetical in- 
dex at the close of the book. 
The “ Practical Illustrations ” at close of many of the Lessons 
suggest the experimental method of study. Any considerable 
amount of experimenting in this subject is, however, impracticable. 
Experiments on living animals and the dissection of animals before 
the class should be avoided. The teacher should prepare carefully 
beforehand all specimens he may exhibit, and everything not needed 
in demonstrating a subject should be kept out of sight. 
Where skeletons, manikins, and charts are not provided in the 
schoolroom, the teacher may make excellent substitutes for them 
by enlarging diagrams and pictures found in larger works on the 
subject. 
The statements in regard to the effects of alcoholic and other 
stimulants are drawn from reliable authorities, and may be regarded 
as nearly correct as the existing condition of our knowledge of these 
subjects will permit. 
iii TABLE OF CONTENTS. 
[For ready reference to any particular subject, see Alphabetical Index at 
close of volume.] 
PAGE 
INTRODUCTION 1 
Part I. 
HOW THE MOVEMENTS OF THE BODY ARE PRODUCED, 
OR THE MO TORY APPARATUS. 
CHAPTER I. — The Solid Framework, or The Osseous System 7 
CHAPTER II.— The Framework Clothed with Flesh, or The 
Muscular System 35 
Part II. 
HOW THE BODY IS NOURISHED, OR THE NUTRITIVE 
APPARATUS. 
CHAPTER I. — How the Food is Prepared, or The Digestive 
System 51 
CHAPTER II. — How the Nourishment is Carried through the 
Body, or The Circulatory System 87 
CHAPTER III. — How Gases are Exchanged in the Body, or The 
Respiratory System 114 
CHAPTER IY. — Waste and Repair of the Body, or The Secre- 
tory System 131 
V vi 
TABLE OF CONTENTS. 
Part III. 
HOW THE BODY IS GOVERNED, OR THE SENSORY 
APPARATUS. 
PAGE 
CHAPTER I. — How All Parts Communicate with One Another, 
or The Nervous System 149 
CHAPTER II. — How the Body Communicates with the External 
World, or The Special Sense-Organs . . 177 
Part IV. 
GENERAL INFORM A TION ON FOODS AND STIMULANTS. 
CHAPTER I. — How to Select Proper Foods and Drinks . . . .211 
CHAPTER II. — The Dangers of Stimulants and Narcotics . . . 230 Fig. 1. — The Skeleton. 
Note. — Point out: 1. Frontal. 2. Parietal. 3. Temporal. 4. Nasal. 5. Malar. 6. Su- 
perior Maxillary. 7. Inferior Maxillary.. 8. Cervical Vertebrae. 9. Clavicle- 
10. Scapula. 11. Sternum. 12. Ribs. 13. Humerus. 14. Radius. 15. Ulna. 
16. Carpus. 17. Metacarpus. 18. Phalanges of Hand. 19. Lumbar Vertebrae. 
20. Ilium. 21. Ischium. 22. Pubes. 23. Femur. 24. Patella. 25. Fibula. 
26. Tibia. 27. Tarsus. 28. Metatarsus. 29. Phalanges of Foot. 
viii LESSONS IN PHYSIOLOGY. 
INTRODUCTION. 
1. At a time when great advancement had already been made 
in mathematics, astronomy, architecture, sculpture, painting, and 
rhetoric, very little was yet known of the structure and uses of 
the parts of the human body. Hippocrates, a Greek philosopher 
who was born 460 years before the time of Christ, and was 
called the “Father of Medicine,” had some general knowledge 
of the human body, more especially of the bones; but, upon 
the whole, his knowledge was very limited, and much that he 
taught was very inaccurate. He taught, for example, that the 
use of the brain was to secrete the mucus of the nose, and 
that the heart and arteries contained air. He had no knowl- 
edge of the nervous system, and supposed that the nerves and 
tendons, or sinews, were the same. 
Erasistratus, about 300 b.c., was the first to make a dissection 
of the human body after death. In ancient times it was a 
violation of law to dissect a human body, and all investigations 
were carried on in secret. Some knowledge of Anatomy was 
obtained by the dissection of monkeys and other animals whose 
organs were supposed to resemble those of man. 
Since the year 1619, when William Harvey made the impor- 
tant discovery that the blood passed from the veins to the 
heart, and from there into the arteries, through the body, and 
back again into the veins, progress in the knowledge of the 
human body has been quite rapid. From that date to the pres- 
ent the science of medicine, which depends upon a knowledge 
of the human body, has made wonderful progress. Great pesti- 
1 2 
LESSONS IN PHYSIOLOGY. 
lences, which formerly swept away people by the thousand and 
ten thousand, are now comparatively rare. Nearly every dan- 
gerous disease is under control, and the prospects for future 
conquests are very encouraging. All this is due to the fact 
that many men have devoted years of study to the structure 
and uses and care of the human body. 
2. The science which treats of the structure, or make-up, of 
the body is called Anatomy, from two Greek words meaning 
to cut apart or dissect. Thus, when we learn what the parts 
of the body are, how they look, and how they are connected 
together, we are learning Anatomy. 
3. The science which treats of the actions and uses of the 
various parts is called Physiology, which means “ a discourse on 
nature.” Thus, when we learn how the blood circulates, how 
the muscles contract, the uses of the various fluids, and how the 
body grows, we are learning Physiology. 
4. The rules which should govern us in taking care of the 
body and preserving it in a state of health are discussed under 
the name Hygiene, a word derived from the name of the Greek 
goddess, Hygeia, who was supposed to watch over the health of 
the people. 
These three subjects, the sciences of Anatomy and Physiol- 
ogy and the art of Hygiene, are usually discussed together in 
schoolbooks under the common term, “ Physiology.” In order 
to a thorough understanding of the lessons in this book, it is 
necessary to know the meaning of a few terms which will 
frequently occur. 
5. All animal and vegetable bodies, or, in other words, all 
living things, are made up of and originate from cells. A cell 
is generally a minute body, requiring a microscope to enable 
us to distinguish it. There are, however, some comparatively 
large cells in the animal and vegetable worlds. The egg of a 
bird, for example, is a cell; and in some fruits, as the orange, 
the cells may easily be seen with the unaided eye. 
A living cell is generally in the form of a tiny bag, and is 
filled with a fluid called protoplasm (first form). In this fluid 
usually is to be seen a still smaller bag called the nucleus 3 
INTRODUCTION'. 
(kernel), and sometimes a dark spot is seen yet within this, 
called the nucleolus (little nucleus). 
Cells vary much in shape: some are globular, some cylindri- 
cal, some flat, some like threads or fibers. They are short-lived 
and are constantly changing their form. New cells are pro- 
duced from old ones, and old ones disappear or become inactive 
and changed in shape. In the blood, millions are born and 
millions die every minute. By their birth, growth, and death, 
the body lives, and all the work of the body is performed in 
and by them. All growth is by the multiplication of cells, and 
death is the cessation of life in all the cells. As far as human 
wisdom and skill can find out, they are the very seat of that 
mysterious something we call life. 
6. The term tissue is frequently used in works on Physiology. 
Let us have a clear idea of what is meant. Generally speaking, 
tissue is a name applied to any part of the substance of the 
body. For example, a portion of the lungs would be called 
lung tissue; a portion of the brain would be spoken of as brain 
tissue, and so on. More strictly speaking, a tissue is any por- 
tion in which the cells and cell arrangement is distinct, forming 
a mass which has peculiar appearance and physical properties. 
Thus, parts made up of cells in the form of fibers are called 
fibrous tissue, as in the tendons and ligaments; parts made up 
of grains or minute masses are called granular tissue, as in the 
liver and other glands; the muscles and nerves, being composed 
of minute tubes, are often called tubular tissue ; parts made up 
of a net-work or meshes of fibers are called connective, or areo- 
lar, tissue. The special study of tissues is really a science by 
itself, and is called Histology. A full discussion is not necessary 
in a work of this kind. 
The tissues are appropriately compared to the materials, as 
wood, stone, brick, glass, etc., which enter into the building of a 
house. 
7. An organ is any part of the body; that is, any collection 
of tissues that does special work, as the brain, the organ of mind; 
the lungs, the main organ of breathing; the stomach, the prin- 
cipal organ of digestion ; the heart, the organ of circulation, 4 
LESSONS IN PHYSIOLOGY. 
and so on. The organs may be appropriately compared to the 
doors, windows, roof, walls, and foundation of a house. 
8. A number of organs working together to perform a com- 
mon work, are called a system. Thus the organs which prepare 
the food are called the Digestive System; those which circulate 
the fluids are called the Circulatory System. Several systems 
working for the same general purpose are called, sometimes, an 
Apparatus. Thus, the Digestive, Circulatory, Respiratory, and 
Secretory Systems are all concerned in the nourishment of the 
body, and taken together are called the Nutritive Apparatus. 
Read carefully the Table of Contents, which may be taken as 
the basis of a complete classification or outline of the parts of 
the body. 
9. Some knowledge of Chemistry is necessary to a thorough 
understanding of all the subjects discussed in Physiology, but 
anything like lengthy explanations cannot be given here. The 
student must be content with a partial understanding, until he 
has studied Chemistry. A few points, however, ought to be 
noticed. 
Of the seventy or more simple elements which are known to 
chemists, the human body contains only fourteen. Of these only 
three — carbon, hydrogen, and oxygen — make up by far the 
greater part of the substance of the body. Oxygen and hydro- 
gen, chemically combined, form water. If a human body weigh- 
ing one hundred and forty pounds be placed in an oven and 
thoroughly dried, it would then weigh but twelve pounds. 
This shows what proportion of the body is water. If the solid 
portion left were put into a very hot furnace for several hours, 
only a handful or two of white ashes would be left; the 
remainder would disappear in the form of an invisible gas, 
which on analysis could be shown to be composed of carbon and 
oxygen. The oxygen of the air has united with the carbon of 
the body. The ashes would be found to consist mainly of salts 
of lime, potash, and soda. Some one has facetiously remarked 
that a man is composed of a few pounds of charcoal (carbon) 
and several pails of water, and he was not far from the truth. 
These few elements are combined in various ways so as to form INTRODUCTION. 
5 
a score or more of distinct substances, as albumen, gelatine, fat, 
sugar, several kinds of salts and acids. 
In the ordinary decay of the body after death, a great many 
chemical substances are formed by the breaking up of com- 
pounds, and the forming of new ones. Many of these new 
substances are very poisonous; therefore a dead body should be 
removed in the most effectual manner, so that the health of the 
living may not suffer from these substances getting into the air 
we breathe or into the water we drink. Bones of the Head. 
Note. — Point out: 1. Frontal. 2. Parietal. 3. Temporal. 4. Occipital. 5. Sphenoid. 
6. Ethmoid. Also: 7. Nasal. 8. Lachrymal. 9. Vomer. 10. Inferior Turbinated. 
11. Palate. 12. Malar. 13. Superior Maxillary. 14. Inferior Maxillary. 
6 Part T. 
ROW THE MOVEMENTS OF THE BODY ARE PRO- 
DUCED, OR THE MO TORY APPARATUS. 
CHAPTER I. 
THE SOLID FRAMEWORK, OR THE OSSEOUS SYSTEM. 
LESSON 1. 
Bones of the Head. 
1. There are 200 bones in the human body, not including the 
teeth nor the minute bones, or ossicles, of the internal ear. Of 
these 200 bones, 34 are in the central line of the body, and are 
single. The remaining 166 are in pairs, one on each side of the 
central line. It is convenient to divide them into three groups: 
bones of the head, bones of the trunk, and bones of the limbs. 
These groups may be again divided into smaller groups. We 
may thus the more easily become familiar with them. By fre- 
quently consulting this and the two following lessons in con- 
nection with a chart or skeleton, you may soon learn to know 
and name all the bones in the body. It is, however, more 
important that you should know the nature and uses of bones, 
and how to care for them, than to know their individual names. 
2. The twenty-two bones of the head, taken together, form 
what is commonly known as the skull. That part of the skull 
which encloses the brain as in a box is called the cranium. There 
are eight bones in the cranium, firmly joined together in the adult, 
and in some cases part of them are found completely grown to- 
gether. You may ask, why the necessity of so many pieces in the 8 
LESSONS IN PHYSIOLOGY. 
cranium ? Why is it not all in one piece, since the bones are so 
closely joined ? If a window contained but one large pane of 
glass, when your ball struck it the whole window would be 
broken. But if it contained a number of small panes, you 
would break only a small part of the window. So with th£ 
bony box which holds the brain. But there are other reasons. 
The bones are solid and firm, as they must be for protection. 
The brain must increase in size as the body grows. The bones 
are at first a little distance apart, and as the brain enlarges they 
have room to enlarge also. (See lesson on Joints.) 
3. The frontal, or front-bone, forms the forehead and a 
portion of the roof of the eye cavities. Exactly opposite the 
frontal is the occipital (back of head). It rests on the spinal 
column, and joins the head to the trunk. In the portion which 
curves under to form a part of the base of the skull is a large 
round opening through which the spinal cord joins the brain. 
The parietal (a wall) bones join each other in the middle line 
of the top of the head like the two sides of the roof of a house. 
They form mainly the sides and top of the cranium. They are 
the most nearly regular in shape of any of the bones of the 
body, being almost rectangular. The temporal bones (from 
tempus, time, because a man begins to get gray hair first on 
that part of the head) form that part of the skull which lies 
mainly between the ears. This bone has three rather distinct 
portions. One which projects as a ridge into the center of the 
floor of the brain cavity is called the petrous portion (from 
petrus, a stone, because this part is one of the first to ossify in 
early life). It contains the delicate parts of the internal ear. 
That part which forms the “ bump ” you can feel just behind 
the ear is called the mastoid portion. It is filled with cavities 
containing air, and which communicate with the cavity of the 
middle ear. That part which spreads out to form the side of 
the cranium is called the squamous (scale-like) portion. 
The sphenoid (wedge-like) is a very irregular bone forming 
a part of the base of the skull. It is joined to all the other 
bones of the cranium, and to nearly all of those of the face. It 
is like the “ keystone ” of an arch, locking the other bones firmly BONES OE THE HEAD. 
9 
together. It has many holes through which nerves and blood- 
vessels of the brain pass. In its center are some large cavities 
containing air, and communicating with the cavity of the nose. 
The ethmoid (sieve-like) bone is irregular and full of cavities, 
also connected with the cavities of the nose. The nerve of 
smell passes through it from the brain to the nose. It lies in 
front of the sphenoid, and mainly between the eye cavities. 
Now write down the names of the bones of the cranium, 
arranging them thus: — 
Bones in Pairs. 
Temporal. 
Parietal. 
Single Bones. 
Ethmoid. 
Sphenoid. 
Occipital. 
Frontal. 
4. The remaining fourteen bones of the head are grouped as 
bones of the face : Nasal, small flat bones forming the “ bridge ” 
of the nose ; the malar, or cheek-bones ; the lachrymal (Greek, 
meaning “ a tear ”), very small bones at the inner, lower corner 
of the eye cavities. The duct which carries the tears down to 
the nose passes through it; the palate bones forming the back 
part of the roof of the mouth ; inferior turbinated (scroll-like), 
one in each nasal cavity; superior maxillary, upper jaw-bones ; 
inferior maxillary, lower jaw; vomer (plowshare), forming the 
bony partition between the nasal cavities. 
The superior maxillary bones contain a large cavity filled 
with air and communicating with the nasal passages. The 
teeth which are not properly classed as bones are set in cavities 
(called alveoli) of the superior and inferior maxillary bones. 
The inferior maxillary is the largest bone of the face, and the 
only bone of the head which is freely movable on the others. 
It has a slight side motion as well as an upward and downward, 
thus making it capable of grinding the food. 10 
LESSONS IN PHYSIOLOGY. 
You should now write down the names of the bones of the 
face, arranging them as directed for the bones of the cranium, 
remembering that only two, the vomer and the inferior maxil- 
lary, are single ; the others are in pairs. 
LESSON 2. 
Bones of the Trunk. 
1. The trunk, or- body proper, contains fifty-eight bones, 
grouped for convenience of description, into: bones of the 
thorax, of the spinal column, and of the pelvis. 
2. The thorax consists of the ribs, the sternum, or breast-bone, 
the clavicle, or collar-bone, and the scapula, or shoulder-blade. 
There are twelve pairs of ribs (occasionally thirteen pairs, and 
sometimes only eleven). The upper, or first seven pairs, are 
joined by separate short pieces of cartilage to the sternum, and 
are called true ribs. The other five pairs are called false ribs. 
Of these, the first or upper three pairs, are joined, but not by 
separate cartilages, to the sternum. The last two pairs are not 
united at all to the sternum, and are called floating ribs. All 
of the ribs are articulated to the spinal column, and have con- 
siderable freedom of motion, rising and falling in breathing. 
As they rise they increase the cavity in the chest by being 
brought more nearly at right angles to the spinal column. 
Tight lacing makes the ribs more curved and shorter, thus 
lessening the size of the thoracic cavity. 
The sternum, so called from its hardness, is somewhat in the 
shape of an ancient short sword. In the adult it is usually in 
three pieces, — the upper, called the manubrium (handle); the 
middle, the gladiolus (little sword); and the lower extremity is 
called the ensiform, or xiphoid appendage. In early life there 
are eight pieces in the sternum, and in old age all the pieces 
are frequently united solidly into one. Sitting too much in a BONES OF THE TRUNK. 
11 
stooping posture, or bending long over one’s work, will cause 
the sternum to sink in by the bending of the cartilages which 
attach it to the ribs, thus making the person flat-breasted, and 
diminishing the space for the organs of the chest. 
The clavicle (key, from its resemblance to an ancient form of 
that article) acts as a brace to keep the shoulder in position. 
When it is broken, the shoulder falls 
downward and forward. It is some- 
what different in the sexes, being a 
little more curved and much heavier 
in men. This is due, doubtless, to 
the fact that men as a rule are ac- 
customed to using' their arms for 
heavier work. Every one has ob- 
served that a woman cannot wield 
an ax or throw a stone with the same 
dexterity that a man can. The shape 
of the clavicle offers the explanation. 
This bone is more frequently broken 
than any other bone in the body, and 
usually by a fall on the shoulder. 
The scapula is somewhat in the 
shape of a mason’s trowel. It con- 
nects the arm to the body by giving 
attachment to several powerful mus- 
cles. The scapula and clavicle are 
sometimes grouped with the bones of 
the upper limbs. 
3. The spinal column proper con- 
sists of twenty-four irregular bones 
called vertebrce (singular, vertebra, 
that which turns). A typical verte- 
bra has: (1) a body or solid portion, 
rounded in front and nearly flat behind; (2) an arch, which is 
made up of (a) two portions next to the body, called pedicles 
(little feet), (A) two laminae (plates), and (c) seven processes 
(projections). Two of these projections are for articulation with 
Fig. 2.—The Spinal Column. 12 
LESSONS IN PHYSIOLOGY. 
the vertebra above and two for the vertebra below; two project 
laterally, one on each side, and are called transverse processes. 
The laminae meet to form a projection backward, which in 
some of the vertebrae is quite long. It is called the spinous 
process, and from this we get the name spinal column (literally, 
a column of spines). The transverse and spinous processes are 
for the attachment of muscles, which are numerous and large 
in this region. The arch forms an opening, which, when all 
the vertebrae are together, makes a continuous channel called 
the spinal canal. In it the spinal cord lies, and is well pro- 
tected from injury by the peculiar shape of the vertebrae. 
The first vertebra is called the atlas, from the name of the 
god of heathen mythology who was supposed to support the 
earth on his shoulders. The second is called the axis, because 
it is the pivot on which the head rotates. It has a peg-like pro- 
jection which fits into the atlas and turns as a pivot when the 
head is moved from side to side. This pivot is held in place by 
a strong ligament, and when a criminal is hung this ligament is 
usually broken, and the pivot presses on the spinal cord at its 
junction with the brain and death results instantly. The head 
rocks backward and forward upon the atlas very much as a 
rocking-chair moves on the floor, except that the rockers of the 
occipital bone fit in grooves of the atlas so that no side motion 
is permitted. 
The mechanical arrangement of the occipital bone, atlas, and 
axis, whereby the two motions of the head, from side to side 
and back and forth, are made, is a wonderful example of adap- 
tation of means to an end. When you nod an affirmative an- 
swer, the occipital bone rocks on the atlas, and the axis and atlas 
are fixed. When you shake your head in denial of a proposi- 
tion, the atlas rotates on the axis, and the occipital bone and 
atlas are fixed on each other. So you see it is a double-acting 
hinge. The atlas is prevented from rotating too far by strong 
ligaments which permit it to go just so far and no farther. 
(See lesson on Joints.) 
The first seven vertebrae, including the atlas and axis, are 
called cervical (of the neck); the next twelve form attach- BONES OF THE TKUNK. 
13 
ments for the ribs, and are called dorsal (of the back) ; the last 
five are called lumbar (of the loins). The lumbar vertebrae 
are the largest; the dorsal have the longest spines. 
The spinal column taken together is admirably adapted for 
the double purpose of a support or axis of the body and a pro- 
tection for a principal portion of the nervous system, the spinal 
cord. Being made up of separate bones it is flexible to a suffi- 
cient degree, yet these bones are so well locked together that 
sufficient rigidity is secured. It is easily deformed, especially 
in young people, by constantly sitting or standing in a bent 
position. You should sit upright and stand straight. Do not 
form habits of stooping, or leaning, or bending over a desk. 
4. The pelvis (a basin) consists of the sacrum, the coccyx, 
and the two innominata bones. The sacrum (sacred, because 
this part of an animal was once used in sacrifices) consists of 
five solidly united and modified vertebrae. The coccyx (cuckoo, 
because it has a fancied resemblance to the bill of that bird) is 
similar to the sacrum in form, being made up of four united 
vertebrae. These two bones are a modified continuation of the 
spinal column. The innominata (nameless, because they do not 
resemble anything) are in early life composed of three pieces, 
the lower, called the ischium, or seat-bone, the front portion, 
called the pubes, or share-bone, and the upper, broad, expanded 
part, the ilium, or hip-bone. The place where the three pieces 
unite is in the form of a deep cup which makes a socket for the 
head of the femur. 
5. There is one bone which has no immediate connection with 
any other bone in the body. It is called the os hyoides, or hyoid- 
bone. The name is from the Greek and means “U-shaped.” 
You can readily find what is called “ Adam’s apple ” in the 
front of the neck. Place your finger just above this and press 
firmly. You feel something solid. It is this bone. Make an 
attempt to swallow while your finger is on the spot. You feel 
the bone rising and moving from under your finger. It gives a 
solid attachment to thirteen pairs of muscles which move the 
tongue, and aid in swallowing and in speech. 14 
LESSONS TN PHYSIOLOGY. 
LESSON 3. 
Bones of the Limbs. 
1. The sixty bones of the upper limbs are: (1) The humerus, 
the long bone of the arm; (2) the ulna, and (3) radius, the 
two bones of the forearm. The upper end of the ulna forms 
the tip of the elbow. The ulna and radius are to some extent 
the reverse of each other. While the ulna forms the main 
part of the joint at the elbow the radius forms the joint at the 
wrist. The ulna is the more stationary, the radius the more 
movable. 
The radius is larger at the lower end, and the ulna larger at 
the upper end. Place your hand on the table with the palm 
down. Now turn the hand over with the back down. Observe 
that the radius, which is on the side next the thumb, seems to 
revolve around the ulna. For this reason it is named the radius, 
or spoke. The ulnar nerve passes near the tip of the elbow, 
and when it receives a sudden jar a peculiar tingling sensation 
is felt in the forearm and hand; we then say we have struck our 
“ funny-bone,” or “ crazy-bone.” (4) The carpus, or wrist, has 
eight bones arranged in two rows. You need not memorize 
their names, but it may be interesting to refer to them. Begin- 
ning with the side next the thumb the first bone in the upper 
row is the scaphoid (boat-shaped) ; the second is the semi-lunar 
(half-moon) ; the third, the cuneiform (wedge-shaped); the 
fourth and smallest of all is the pisiform (pea-shaped). Begin- 
ning next the thumb in the second or lower row, we have first, 
the trapezium; second, the trapezoid; third, the os magnum 
(large bone), the largest of all; and fourth, the unciform 
(hooked). The bones of the wrist are small and rounded, 
firmly bound together with ligaments. This arrangement se- 
cures great strength, combined with freedom of motion in all 
directions. (5) The metacarpus (beyond the carpus), or hand, 
consists of five long bones enlarged at the ends. The bones of 
the fingers are called (6) phalanges (rows of soldiers). There 
are fourteen of them, three to each finger and two to the thumb. BONES OF THE LIMBS. 
15 
2. The sixty bones of the lower limbs are: (1) The femur, 
or thigh-bone, the longest and heaviest bone in the body. The 
height of the person depends more on the length of this bone 
than on any other; that is, a tall person is so because this bone 
is much longer; not because all the bones are longer. (2) The 
tibia (a flute, because used as such in ancient times) is com- 
monly known as the shin-bone. It is the principal bone of the 
lower leg. It has a sharp ridge in front, which comes just be- 
neath the skin, and blows on this part are apt to be painful, and 
wounds are made which are sometimes difficult to heal. (3) The 
fibula (a brace) is a slender bone fixed to the tibia at each end, 
but standing at some distance from it in the middle. It 
strengthens the leg, helps to brace the ankle, and serves to 
attach several powerful muscles. (4) The patella, or knee-cap, 
is in the shape of a chestnut, and lies over the heads of the 
femur and tibia, and glides upon them as the knee is bent. Its 
use is to lessen friction and protect the joint. (5) The tarsus, 
or ankle, consists of seven bones. The largest is the os calcis, 
or heel-bone. It projects backward and downward, and gives 
attachment to the powerful tendon of the large muscles of the 
calf of the leg. The astragalus is that bone which joins the 
ankle with the leg. The cuboid, the scaphoid, and the internal, 
middle, and external cuneiform, are smaller, and are placed in 
front of the astragalus. (6) The metatarsus (beyond the tar- 
sus) consists of five long bones forming the instep of the foot. 
(7) The phalanges, fourteen in number, are the bones of the toes. 
3. A glance at the skeleton will reveal many resemblances 
between the bones of the upper and those of the lower limbs. 
The number of bones is the same in each. The patella has 
apparently no corresponding bone in the upper limbs, but the 
olecranon process (tip of the elbow) occupies a corresponding 
position, and in early life is a separate piece. 
Point out as many resemblances and differences as you can in 
the bones of the upper and those of the lower limbs. What bone 
corresponds to the femur ? What to the tibia ? to the fibula ? to 
the metatarsus ? 16 
LESSONS IN PHYSIOLOGY. 
LESSON 4. 
The Joints, or Articulations. 
1. The human body is a wonderful piece of mechanism. This 
is shown very forcibly by the manner in which the bones are 
joined together to form the skeleton, or framework. Every joint 
is a perfect machine of its kind. Before we can understand this 
part of the human mechanism, we must know something of the 
parts which go to make up a joint. 
The parts of a movable joint are: the edges or extremities 
of two bones, ligament, cartilage, synovial membrane, and 
synovia. 
2. Ligaments are bundles or bands of fibrous tissue, pliable, 
elastic, and very strong, which connect the bones at the joints 
in a manner similar to leather or strap hinges on a door. Some 
are quite thin and ribbon-like; others are thick, heavy bands; 
others are like cords. Some simply pass from one bone to the 
other, across the joint; others completely surround the joint as 
with a cap. Such are called capsular ligaments, and are found 
in all joints which have much movement. In the knee-joint, 
strong, cord-like ligaments cross each other between the ends of 
the bones like the letter X- If all the ligaments be cut through, 
the joint generally falls apart. This is not always easy to do, 
as the ends of the bones are frequently irregular, and sometimes, 
as in the knee and elbow, lock into each other; besides, the 
ligaments are very tough, and it requires a very sharp knife to 
sever their fibers. 
When a bone is dislocated (put out of place), the ligaments 
are usually torn, or very much strained, and a long time is re- 
quired for them to recover fully their original condition. There 
are some very rare instances, however, where the ligaments, 
being unusually long and elastic, the person is able to dislocate 
and put back certain joints, as the hip and shoulder, at will. 
Such persons cannot, of course, perform all kinds of work. 
The ligaments are so tough that the bone may be even broken 
near the joint without tearing them. THE JOINTS, OR ARTICULATIONS. 
17 
3. Cartilage, or gristle, is that bluish pearly white substance 
seen on the ends of the bone when a fresh joint is cut open. All 
bones are at an early stage cartilage, as will be seen in a future 
lesson; but the kind of cartilage found in the joints and some 
other parts of the body never changes to bone, and is called 
permanent cartilage. A thin layer of this kind covers the ex- 
tremities, or edges, of all bones in the joints. It is much softer 
than bone, although quite firm, and acts as a cushion to lessen 
shocks, as in walking, running, and leaping. In some joints, 
as in the lower jaw with the temporal bone, and in the spinal 
column, a separate piece of fibro-cartilage (a variety containing 
fibrous tissue) lies between the bones. The weight of the body 
in an upright position causes considerable compression of these 
cartilaginous discs of the spinal column, but they return slowly 
to their original condition when the weight is removed. Hence 
a man is actually about half an inch shorter in the evening 
than in the morning. These fibro-cartilages in the spinal 
column, by yielding when the body is bent, permit a consider- 
able bending of the axis of the body. 
4. In machinery, parts which have a “ bearing ” on each 
other, as it is called, must be oiled to lessen the friction. The 
movable joints of the body are exactly like the bearings in 
machinery — they need lubricating. Nature has provided an 
arrangement by which they are self-oiling. A thin membrane 
inside of the ligaments encloses the joints, and is attached by its 
edges to the bones near their ends. In very early life it is a 
complete bag attached by its outer wall to the ends of the 
bones ; but later, the part within the joint disappears, leaving 
it like a short, wide tube, with the bones for plugs at the ends. 
The inner surface of this membrane secretes a slippery, trans- 
parent fluid, resembling the white of an egg, and called synovia, 
or “ joint-water.” If this bag is punctured, the synovia runs 
out, and temporary stiffness of the joints will follow. How- 
ever, in healthy persons the wound will close up, and a new 
supply of synovia will be secreted. Disease of this membrane 
may result in permanent stiffness of the joint. 
5. Joints Classified. — Anatomists have described joints as 18 
LESSONS IN PHYSIOLOGY. 
belonging to three principal classes, which are again divided 
and subdivided. A full description of all the kinds will be 
found in Gray’s “Anatomy,” and other large works on the subject. 
These general classes are movable, immovable, and mixed. 
The term immovable must not be taken in a literal sense, as 
all joints are capable of some movement when great force is 
applied. The nearest to a perfectly immovable joint are some 
of those between the bones of the skull; but in early life all are 
capable of some movement. 
The so-called movable joints are found mostly in the limbs, 
where great freedom of motion is needed. The most completely 
movable joint is the ball-and-socket joint, such as the hip 
and shoulder. The hemispherical extremity of one bone fits 
into a cup-like cavity of another. So perfect is this fitting in 
the hip-joint that even when all the ligaments are cut the bone 
will be held in place by the pressure of the atmosphere, just as 
when you moisten a smooth coin and make it adhere to the 
window-pane by pressing it slightly. In the shoulder the 
cavity is shallower than in the hip-joint, but this allows still 
greater freedom of motion, although making the joint more 
liable to be dislocated. In fact, surgical records show that the 
shoulder is more frequently put out of place than any other 
joint. The knee, ankle, and elbow are examples of hinge-joints, 
the motion allowed being only in two directions, — back and 
forth. The rotary or pivot-joint, as already described, is found 
in the atlas and axis. The immovable joints are capable of 
motion only under extreme circumstances. Those between 
the bones of the cranium are called sutures (seams), and are 
somewhat like the dovetailing of cabinet-work — projections 
from one bone fitting into indentations in another. In the 
mixed articulations the motion is produced, not by the gliding 
or turning of one bone on another, but by both bones being 
fastened to a fibro-cartilage, which, by its yielding, permits 
motion. FORMS, NATURE, PROPERTIES, AND USES OF BONES. 
19 
PRACTICAL ILLUSTRATIONS. 
At the butcher’s stall procure a fresh, whole joint from the leg of an ox or 
sheep. Trim off the fat and lean meat, if any. Work the joint to show how 
the bones move inside of the ligaments. Cut through the ligaments with a 
sharp knife, and thus expose the cartilaginous ends of the bones. Observe 
the synovia, which will run out the instant you penetrate the ligaments. The 
synovial membrane is simply the delicate, transparent lining of the inside of 
the capsular ligament; and you may not be able to separate it, but you can 
observe how smooth and moist it is. 
Notice the smooth, bluish white ends of the bones. Observe how firm, yet 
how soft, they are. Try your knife on them. You cannot cut deep. That which 
you can cut with the knife is the cartilage. The bone will resist the knife, 
unless it be from a very young animal. 
When you have cut nearly all the ligaments through, try to tear the joint 
apart. You will find it not easy to do, so strong are the uncut portions of the 
ligament. 
LESSON 5. 
Forms, Nature, Properties, and Uses of Bones. 
1. Bones are of many different shapes, the form of each par- 
ticular bone being that which adapts it to a particular use. 
Where a cavity is enclosed, as in the head, most of the bones 
are flat, or rather like parts of the shell of a nut, concave on 
one side and convex on the other. The ribs are flat and curved 
so that taken together they form a cage for the lungs and 
heart, but by their movements it becomes an extensible cage 
which can enlarge itself and permit air to enter the cells of the 
lungs. The bones of the limbs are mostly cylindrical with en- 
larged extremities. The cylindrical form is the strongest in 
proportion to the weight and size. The greater size at the 
ends gives more room for attachment of muscles and surface 
for the bearing of the joints. Those which have enlarged ends 
are called long bones by the anatomists, although some of them, 
as the phalanges, are comparatively short. The small bones of 
the wrist and ankle are called short bones. They are peculiarly 
well adapted, when bound together by ligaments, to form joints 20 
LESSONS IN PHYSIOLOGY. 
where great variety and quickness of motion is necessary. The 
rapid and varied motions of the hand on the wrist, required in 
many kinds of handicraft, could not be produced by any other 
kind of mechanical contrivance. The vertebrae, some of the 
bones of the head, and the bones of the pelvis are classed as 
irregular bones. The irregularity in the shapes of bones is not 
an accidental occurrence. Every curve and projection, every 
ridge and hollow, are for a purpose, either for the attachment 
of certain muscles, to take part in the formation of a cavity for 
enclosing delicate organs, or for the passage of blood-vessels 
and nerves. The long bones are levers for the muscles in 
producing the various motions of the body. 
2. All bones are covered except at their articular extremities 
and edges with a thin, tough membrane called the periosteum 
(around the bone). It is'closely connected with the bone sub- 
stance, and appears to be a part of it, yet by care it may be 
separated. It is almost completely made up of a fine net-work 
of blood-vessels. From it the bones derive their blood-supply, 
the minute vessels dipping from it down into the bone sub- 
stance. When it is peeled from a fresh, young bone, minute 
red points may be observed on the surface of the bone. They 
are the places where blood-vessels which enter the bone have 
been broken. In old age the periosteum grows thin and more 
adherent to the bone. In a young and vigorous person this 
membrane may be dissected away and a portion, or even the 
entire bone, be cut out, and in a short time a new growth of 
bone from the periosteum will have taken place. This is one 
of the wonderful feats of modern surgery. Skillful surgeons 
have saved many a limb from amputation by this operation. 
The cavities of long bones are lined with a similar membrane, 
called the endosteum (within the bone). This membrane is 
supplied with blood by a few main blood-vessels which enter 
the bone through openings about as large as a pin, in the 
body of the bone. 
3. Bone substance appears to the unaided eye to be made up 
of two rather distinct kinds of tissue, which are usually described 
as compact and cancellous tissue. There is, however, no real FORMS, NATURE, PROPERTIES, AND USES OF BONES. 
21 
difference of tissue, the compact being simply an apparently 
solid mass of bone with no openings, or spaces, while the cancel- 
lous (lattice-like) tissue is the same bony substance containing 
many spaces filled during life with marrow and blood-vessels, 
mid in dead bone with air. In the flat, irregular, and short 
bones the compact tissue is mainly on the surface, and the 
cancellous in the interior. In long bones the compact tissue 
forms nearly the entire shaft, or cylindrical portion, and the 
cancellous tissue makes up nearly all of the extremities except 
a thin layer on the surface. Thus, where strength is required 
with little bulk, the compact tissue is found, and where bulk 
with little weight is needed cancellous tissue is found. 
4. In the dry bone of the leg of an ox or sheep, you will 
observe a large cavity running through the entire shaft. In 
the living animal this cavity is filled with a soft, oily substance 
called marrow. In adult bones it is of a yellow color, and con- 
sists mainly of fat, throughout which some blood-vessels and 
nerves are distributed. In young and growing bones, and 
largely in the ends of all bones, it is of a red color, and consists 
mainly of blood-vessels. The use of the marrow is mainly to 
furnish protection for, and a means of distribution of, the numer- 
ous blood-vessels which are needed to nourish the bone. In 
early life, it is supposed to perform an important office in the 
manufacture of blood-corpuscles. The student is referred to 
recent large works on Physiology for a discussion of this subject. 
5. The flat bones of the skull are made up of two plates, or 
tables, of compact tissue, with a layer of cancellous tissue be- 
tween, called the diploe. There is an obvious advantage in this, 
as the shock of a blow on the head is lessened. Sometimes a 
blow on the head causes no external fracture, yet the person 
continues to have some brain trouble — perhaps remains uncon- 
scious. The skillful surgeon, by means of an instrument called 
a trephine, cuts out a circular piece of bone, and through this 
opening explores the under surface of the bone. Frequently it 
is found that the inner table is broken, and a portion of bone 
presses upon the brain. This being adjusted, rapid recovery 
results. It also happens sometimes that a blow upon the top of 22 
LESSONS IN PHYSIOLOGY. 
the head causes fracture of the ethmoid bone, without injury to 
the other bones. The force is transmitted through the arch of 
the skull, and the parts of the ethmoid, being delicate, are 
broken. Rarely is there serious trouble, however, the only 
evidence that the ethmoid is broken being shown by examina- 
tion after death, which may occur from other causes years after- 
ward. This shows how well protected the brain is in its bony 
box. When the blow is direct, the force is distributed through 
the bones, and when indirect, the roundness of the skull causes 
the missile to glance off. Injuries to the brain, although they 
do occur, are comparatively rare. 
6. Minute Structure of Bone. — Although to the unaided eye a 
piece of bone seems to be a solid mass like a rock, yet if it be 
ground down very thin and examined under a high power of 
the microscope, with a good light, it appears to be full of holes, 
which contain as much space as the bone matter itself. By 
examining both cross and longitudinal sections, it can be shown 
to contain numerous little channels running in various direc- 
tions. These are called Haversian canals, from the anatomist, 
Havers, who first discovered them. The bone substance is 
arranged around these channels in many thin layers, not unlike 
the coats of an onion, and some investigators have described 
little fibers running through these layers, as it were, pinning 
them together. In the midst of these layers are seen what 
appears to be oval, dark spots, with dark lines radiating from 
them, and joining the Haversian canals. These dark spots are 
called lacunce (little lakes), and the lines canaliculi (little canals). 
The lacunce are really bone-cells, and the canaliculi are processes 
or branches of the cells. Through all these, in the living bone, 
the plasma, or thin part of the blood, filters as through a sponge, 
and brings the material which builds up and keeps the bony 
tissue in repair. 
7. Composition of Bone. — Two simple experiments will prove 
that bone is composed of two distinct kinds of matter. (1) If a 
long bone be immersed in a weak acid for a day or two, it will 
become soft and flexible so that it may be tied in a knot; yet it 
retains the same bulk and shape, and microscopic views of sec- FORMS, NATURE, PROPERTIES, AND USES OF BONES. 
23 
tions of it show the same structure as it had before. It will, 
however, have lost in weight, and the acid can be shown to 
have united with earthy, or mineral salts. 
(2) Again, if a bone be put into a hot fire, 
and left until it has burned perfectly white, 
it will be found to have lost in weight, and 
be very brittle and fragile, yet retaining 
the original form and structure. It is 
evident that the acid removed the part 
which gives the bone solidity, and the fire 
removed the part which gives it toughness 
and elasticity; also that the parts were inti- 
mately blended. The part removed by the 
acid is called mineral, or earthy matter, 
and forms about two-thirds by weight of 
the entire bone. It consists mainly of phosphate of lime and 
carbonate of lime, the former weighing about one-half, and 
the latter about one-tenth, of the entire bone. The part re- 
moved by the fire is mainly gelatine, usually spoken of as 
organic, or animal matter, because not produced in the mineral 
kingdom, but a product peculiar to living beings. A portion 
of the gelatine is dissolved out of bones when they are boiled 
for soup. It is the jelly we see when pigs’ or calves’ feet have 
been boiled and allowed to cool. Gelatine forms a large part 
of the skins of animals. When united with tannic acid it 
forms leather. The glue used by cabinet-makers and others is 
hardened gelatine made from the waste portions of skins of 
animals used in making leather. 
In young persons the proportion of organic matter is greater 
than in adults, and the bones are consequently softer and more 
flexible. In old age the proportion of inorganic, or mineral 
matter, is greater, and the bones are harder and more brittle. 
In the disease called “ rickets ” there is a deficiency of mineral 
matter, and the bones become bent and deformed by the mere 
weight of the body. There are some rare cases of a disease in 
which there is a great deficiency of the organic matter, and 
bones become so fragile that the mere contraction of the muscles 
Fig. 3. — Structure of 
Bone Enlarged. 24 
LESSONS IN PHYSIOLOGY. 
in moving the limbs may break the bones. Works on surgery 
record cases where men broke their bones by simply turning 
over in bed, or by throwing a club, or catching a toe in the 
carpet. 
8. Properties of Bones. — Bones possess certain properties 
which make them peculiarly adapted to their uses in the body. 
They are flexible and elastic to a certain degree; were they 
much more so, they could not support the weight of the body. 
They are more flexible in youth, when the weight of the body 
is less, and the activity greater. The bones of a child will bend 
before they will break. They have a certain degree of hardness 
which fits them for protecting delicate organs within, and gives 
them the required stiffness for levers for the muscles, and for 
supporting the weight of the body. 
Although of no value in a physiological sense, it is interesting 
to know that bones are exceedingly durable. Fossil bones have 
been found which bear evidence of having belonged to animals 
which existed before man came upon the earth. One case is 
recorded where the bones of a mastodon were found in such an 
excellent state of preservation that the workmen who dug them 
up greased their boots with the marrow. Some of these fossil 
bones contained gelatine enough to make a nutritious soup. 
Bones, when used as levers, are about twice as strong as oak 
wood, more than three times as strong as lead, and twenty-two 
times as strong as sandstone. 
9. Uses of Bones. — From what has been said in the foregoing 
lessons, the pupil may infer many of the uses of the bones in 
the human body. They may be summed up under three heads : 
{1) For support: They form the framework around and within 
which the soft parts are arranged and kept in position. Without 
the bones the body would be a shapeless mass. (2) For protec- 
tion : The delicate brain, the yielding lungs, the massive liver, 
the stomach and intestines, the principal blood-vessels and nerves, 
the sensitive eye, and the delicate mechanism of the internal 
ear, are all guarded and protected by the bony framework. (3) 
As aids to motion and locomotion: The muscles, which are the 
prime movers of the body, would be of little use were it not for FORMS, NATURE, PROPERTIES, AND USES OF BONES. 
25 
the bones to form solid points of attachment, and to be used as 
levers in producing the great variety and complexity of motions 
of which a trained human being is capable. What a wonderful 
machine is the human hand! The numerous small bones, with 
their muscles acted upon by nerves, are capable of executing an 
almost infinite variety of movements, which may follow each 
other in such rapid succession that the eye cannot follow and 
keep trace of them. 
The bones of animals are useful to man in various ways. 
Many useful and ornamental articles can be cut from them. 
Ground to powder, they make the best fertilizer known. They 
are a source of phosphorus, phosphate of soda, and superphos- 
phate of lime, which are valuable chemicals used in the arts 
and in medicine; also of animal charcoal, or bone-black, used 
for making shoe-polish, for painting, and in the purification of 
sugar. 
PRACTICAL ILLUSTRATIONS. 
1. Get the long bone of a turkey’s or chicken’s leg. Find a wide-mouthed 
bottle, long enough to receive it. Pill the bottle about five-sixths full of water; 
then fill up with muriatic acid, and shake or stir until water and acid are mixed. 
Let the bone remain in this diluted acid for two days. If then the bone is not 
soft enough to be tied in a knot, add a few drops more acid, and let stand 
another day. If you get too much acid, it will dissolve the gelatine also. 
2. Get from the butcher a large piece of the bone from the leg of an ox. 
See that it is the end and part of the shaft of a long bone. Saw it through length- 
wise with a meat-saw. Observe the compact and cancellous tissues and the 
marrow. 
3. Procure, if possible, a piece of fresh bone from the leg of a calf or lamb. 
Try to separate the periosteum with a knife. Observe the red points where the 
blood-vessels are broken when the membrane is torn off. 
4. Get a large piece of beef-bone, and, after cleaning off all ligaments and fat, 
weigh it carefully and note the weight. Place it in a hot fire in the stove or 
fireplace, and let it remain about three hours, or until it turns perfectly white. 
When cool, observe that it has not lost in bulk, and that the shape is not 
changed. Now weigh it carefully again, and note the loss of weight. Strike it 
with a hammer, and observe how easily it is broken. When broken, notice the 
structure within, and compare it with the unburned specimen of No. 2. 26 
LESSONS IN PHYSIOLOGY. 
LESSON 6. 
Development, Growth, and Hygiene of Bones. 
1. Development of Bone. — In man, and in all of the higher 
vertebrate animals, the skeleton, or framework, is, in the embryo 
state, composed of cartilage and membrane. As it develops, bony 
tissue appears gradually, taking the place of the cartilage or 
membrane. In the lowest forms of vertebrate animals, as in 
some of the fishes, the skeleton remains cartilaginous through 
life. This is another illustration of the great law in nature that 
the very young of higher animals resemble the adults of the 
lower forms. Except in the case of some of the flat bones of 
the head, all the bones in the human body are said to be devel- 
oped from cartilage; that is, the cartilage cells gradually dis- 
appear and are replaced by bone cells, and bony matter is 
deposited within and between the cells. This process is called 
ossification (bone-making). The process of ossification begins 
before birth, and is not entirely completed in all the bones 
until old age. At birth a part of nearly every bone is ossified, 
and some are almost completely so. 
The development of bony matter begins at certain points, 
called centers of ossification, within the bone, and proceeds in all 
directions from these centers. In short bones there is usually 
but one center of ossification; in long bones, usually three. In 
some irregular bones there are several; in the sacrum, as many 
as thirty-five. 
2. The shaft of a long bone is developed first as a separate 
piece from one center; the heads, or articular extremities, from 
separate centers. In the skeleton of a human being less than 
twenty years of age, a plainly marked line may be seen be- 
tween the head and shaft of each long bone. A smart blow 
may cause a separation of the head from the shaft. This 
takes place sometimes during life, by accident; that is, a 
bone may break at this point more easily than at any other. 
The epiphysis (growing upon), as the head of the bone is 
called in this early stage, does not become completely united DEVELOPMENT, GROWTH, AND HYGIENE OF BONES. 
27 
to the diaphysis (growing through), or shaft, until about the 
age of twenty. Observations on animals show that they live 
about five times as long as the time required to complete the 
union of these parts. Thus, in the dog, it takes place at four 
years, and its lifetime is about twenty years; in the horse at 
six, and its lifetime is thirty years. Unless man is an excep- 
tion to the rule, he ought, then, to live to the age of one hundred 
years, and we need not hope to see the term prolonged much 
beyond this period. There are no authentic records of men in 
modern times, at least, who have lived beyond one hundred 
and six years. 
3. At birth the flat bones of the skull are separated from each 
other by spaces which are filled by a soft membrane. At several 
points where corners of bones meet, these spaces are of consider- 
able size. One just back of the forehead is diamond-shaped, 
and sometimes an inch in diameter. This usually remains open 
until the second year, and rarely through life. The others are 
smaller, and are situated at the back and sides of the head. 
These spaces are called fontanelles (little fountains), because the 
large arteries at the base of the skull may be felt lifting the 
brain at each pulsation. Sometimes new centers of ossification 
start in the membrane of a fontanelle, or between the edges of 
the different bones, and the results are separate small bones, 
called Wormian bones, from Wormius, who first described them. 
4. In the development of the bones of the head certain open 
spaces, or cavities, are left. Some of these have already been 
mentioned. The one in the frontal bone just over the eyes is 
called the frontal sinus. It is caused by a separation of the 
outer and inner plates of the bone. This cavity varies much in 
size, sometimes not over an eighth of an inch, and again over 
an inch in diameter. For this reason it is impossible to judge 
of the exact size of the brain by measuring the outside of the 
skull. The thickness of the bones of the skull also varies much, 
— from an eighth of an inch to one inch or more. 
These cavities all communicate with the air-passages of the 
nose, and are lined with mucous membrane. The troublesome 
disease called nasal catarrh is an inflammation of the mucous 28 
LESSONS'IN PHYSIOLOGY. 
membrane of the nasal passages, and sometimes extends to these 
cavities in the different bones of the head. In a common cold 
in the head they are sometimes inflamed and painful. Exposure 
to very cold air may affect this membrane, and serious results 
follow. The well-known senator, Roscoe Conkling, died from 
inflammation of the brain, caused by an inflammation of the 
mucous membrane lining the cavities of the mastoid process, 
the direct cause of which was exposure to cold in the severe 
“blizzard” which occurred in New York a few years ago. 
5. Small bones, about the size of a grain of corn, are found in 
some very muscular men, growing in the tendons of certain 
muscles of the hands and feet, where such tendojis glide over a 
joint. Such bones are called sesamoid bones, from their resem- 
blance to a certain seed (sesame). The patella is really a sesa- 
moid bone in the tendon of the large muscle which extends the 
leg. It is the only sesamoid bone which is present in all indi- 
viduals. The use of these bones is to lessen friction. They act 
in a manner similar to pulleys. 
In one or two cases on record a bone has been found extend- 
ing from the hyoid bone to the temporal. It is called the epi- 
hyal bone. 
6. Growth and Repair of Bone. — Like other parts of the body, 
bone is constantly renewing itself, old material being removed 
and new taking its place. The change is not so rapid as in the 
softer tissues, and not so rapid in old bones as in young, yet it 
is going on, as certain experiments on animals prove. If a sheep 
be fed with madder, a vegetable red coloring-matter, in a day or 
two the bones will be tinged with red. If the madder be dis- 
continued the original color will return. In young animals a 
single day is sufficient to show the reddish tinge. In older 
animals it requires a longer time. 
When a bone is broken nature immediately sets to work to 
repair the injury. At first a thin fluid is poured out on the 
broken surfaces, and in a few days this becomes thick like jelly. 
New bony matter develops within this provisional callous, as it 
is called, and the bone is welded, as it were, together. There is 
always more of the new material than what would be merely DEVELOPMENT, GROWTH, AND HYGIENE OP BONES. 
29 
necessary to unite the parts. This causes a knot, or lump, in the 
bone at the broken place. In young and vigorous persons this 
extra amount of material is in time almost or entirely absorbed 
and removed. In old persons it usually remains through life. 
A broken bone should be “set”; that is, the ends brought as 
nearly evenly together as possible; otherwise more or less de- 
formity of the limb will follow. This adjustment is not always 
easy to accomplish, as the muscles by contracting tend to pull 
the fragments, and cause them to lap over each other. Fre- 
quently when the surgeon has taken all possible care to set a 
bone and keep it in place, carelessness on the part of the patient 
or his attendant, may cause displacement and subsequent de- 
formity. Then the surgeon may be blamed, and even prosecuted 
at law, for what was not his fault at all. It usually requires 
five or six weeks for a broken bone to become united, and then 
it should be used with care for some time longer. 
7. Hygienic Summary. — Hints on the proper care of the 
bones have been given incidentally in the foregoing pages. The 
following is a summary of hygienic advice based upon the anat- 
omy and physiology of bone : — 
(1) Do not try to hasten the process of learning to walk, 
especially if the child be “ fleshy.” Its weight may cause bend- 
ing of the long bones of the legs, producing “ bow-legs ” or 
“ knock-knees.” Let the child make efforts to stand on its feet. 
Do not place it upon its feet, nor allow it to remain long stand- 
ing even when it has arisen by its own efforts. Deformities of the 
lower limbs may be produced by the child getting into a habit 
of placing the soles of its feet together as it lies in the cradle. 
(2) Care should be taken that the child does not sleep always 
upon one side, as this may cause one side of the head to grow 
larger than the other or produce deformity in the shoulder. 
(3) Pupils in school should not lean over their desks too 
much. Desks should not be too high, as this will throw one 
shoulder higher than the other; nor too low, as this will produce 
“ stoop-shoulders.” 
(4) Ladies should not be so foolish as to try to produce a 
small waist by tight lacing. A prominent physician once re- 30 
LESSONS IN PHYSIOLOGY. 
marked that tight lacing was a good thing, as it killed all the 
foolish girls, and permitted the wise ones to grow to woman- 
hood. This was stating it rather strong, but certainly it is a 
foolish custom, for not only does it produce actual deformity of 
the bones of the thorax and injure the internal organs, but it 
destroys the natural shape of the body, and thus violates a law 
of taste in art. Really sensible and refined people do not 
admire an unnaturally small waist. The Greek statues of beau- 
tiful women, which have been admired by artists the world 
over, do not show small waists. There is nothing objectionable 
in wearing a corset if it fit the body and be not tightly drawn 
by lacing. A corset should be laced comfortably close with 
elastic cords, so that all movements of the body may be made 
with perfect freedom. 
(5) Young people should avoid sitting or standing long at 
a time in one particular position, as undue pressure on any 
particular part may impede the proper circulation of the blood, 
and it must be remembered that bones demand a supply of 
blood as well as other parts of the body. Moreover, when the 
bones are flexible, long-continued pressure upon them will cause 
a gradual but sure bending. 
(6) An erect posture should be maintained when sitting or 
standing; the shoulders should not be permitted to fall forward. 
Youth is the time when good or bad habits are formed. Try to 
form habits of carrying the body with ease and grace. If you 
do not think occasionally about the necessity of proper habits of 
sitting and standing, you will easily fall into habits of stooping, 
or lounging, or leaning, which will surely tell, when you have 
grown to manhood or womanhood, in rounded shoulders, con- 
tracted chest, and perhaps crooked spine. 
(7) Old persons should be particularly careful to avoid falls, as 
a fall which would not injure a young person in the least may 
produce serious fractures of bones, — fractures that may never 
completely unite. 
(8) The bone is a living, growing part of the body, and 
needs proper nourishment; hence, good food, fresh air, proper 
exercise, avoidance of excesses of all kinds ; or, in other words, DEVELOPMENT, GROWTH, AND HYGIENE OF BONES. 
31 
whatever tends to the making of pure blood, is essential to 
the healthy condition of bones as well as of other parts of 
the human body. Does the use of alcoholic stimulants affect the 
bones? Perhaps not directly, but certainly it does indirectly, 
as will be inferred from what has already been said. Alcohol 
interferes with the proper nourishment of the body, and the 
bones will inevitably suffer in time as a natural consequence. 
An illustration of this is found in some cases of professional 
beggars in cities, who give their children gin or whiskey when 
they are babies, for the purpose of arresting development, and 
keeping them small and puny, that they may excite compassion 
in those from whom they beg. 
PRACTICAL ILLUSTRATIONS. 
1. Get a pig’s foot from the butcher. Boil it until the meat separates readily 
from the bones. Select one of the long bones, and, having cleaned it thoroughly, 
see if you can find the line of union of the articular head (epiphysis) with the 
shaft. Strike it a smart blow with a stick. A separation will take place at this 
point. This experiment will be successful nearly every time, because animals 
that are slaughtered for food are usually those which have not yet reached the 
age when the bones have become completely ossified. 
2. If you can find the skull of any small animal, as a cat or dog, break it and 
find the air-cavities in the bones. The dry skulls of oxen or hogs may frequently 
be procured for this purpose. In the cat a very large cavity may be observed in 
the mastoid process. 
EXERCISES FOR REVIEW OF THE OSSEOUS SYSTEM. 
[These questions are purposely arranged promiscuously, with no references 
to any particular lesson or section, that the pupil may exercise his skill in 
finding answers to them. He should first try to answer the question without 
referring to the book ; if he cannot do this, let him search for the answer in the 
foregoing pages, using the index at the end of the volume, if necessary, in find- 
ing that part of the text which treats of the subject.] 
1. What is the advantage, if any, of so many bones in the cranium ? 
2. Name three general uses of hones. 
3. What are the parts of a joint ? 
4. What are the uses of ligaments ? 
5. Why is a man taller in the morning than he is in the evening ? 
6. What bones glide upon each other when you nod an affirmative answer ? 
7. What is ossification ? When does it begin ? When is it completed ? 
8. What is the skeleton in the earliest stage of its existence ? 
9. What lubricates the joints ? What is the most movable joint in the body ? LESSONS IN PHYSIOLOGY. 
10. Wliat is the cause of “bow-legs” and “ knock-knees ” ? What causes 
round shoulders ? 
11. What part of a bone is removed by burning ? 
12. At what period of life would you find yellow marrow in the bones ? 
What is the composition of yellow marrow ? of red marrow ? 
13. What bone has a pivot on which the head is rotated ? 
14. What part of a bone is dissolved by an acid ? 
15. Where would you find fibro-cartilage ? 
16. How do alcoholic stimulants affect the bones ? 
17. Can you state one argument in favor of tight lacing ? 
18. What are Haversian canals ? What is their use ? 
19. Where and what is the frontal sinus ? 
20. What is the periosteum and its use ? 
21. What is the synovia H What is its use ? 
22. Name the first and second vertebrae ? What vertebrae are the largest ? 
23. What part of a bone is partially dissolved when it is boiled for soup ? 
24. What is a suture ?■ 
[The above and many more similar questions may be assigned for review 
lessons after the class has completed the study of the osseous system. The 
teacher may, as an occasional exercise, demand written answers to questions 
requiring the pupil to use his own language, and not that of the text-book.] DEVELOPMENT, GROWTH, AND HYGIENE OF BONES. 
33 
Fig. 4. —Right Hand and Forearm. 
A, Palmar, or front view; B, Dorsal, or back view. 
Fig. 5. — Front and Side Views oe Knee-Joint. 
A, Femur; B, Patella; C, Tibia; D, d, Fibula. 1, Occipito-frontalis; 2, Orbicularis palpebrarum; 9, Platysma myoides; 10, Deltoid, 
14, Biceps; 11, Pectoralis major; 23, Sartorius; 33, Gastrocnemius. 
Fig. 6. — Muscles. Front View. 
Note. — Advanced students may name tlie muscles referred to by the other figures. 
34 CHAPTER II. 
THE FEAMEWOEK CLOTHED WITH FLESH, OE THE MUSCULAK 
SYSTEM. 
LESSON 7. 
General Description of Muscles. 
1. With some slight exceptions, which will be mentioned, in 
another place, all motions of the body are produced by contrac- 
tions of bundles of fibers, called muscles. They are the lean 
meat of an animal, and give general form to the body and make 
up the greater part of its weight. The angular space where 
two or more large muscles lie side by side is usually filled with 
fat, which does not interfere with their action, but gives the 
body a more even outline. 
The skin contains numerous very small muscles, which con- 
tract when exposed to cold and raise little lumps, producing 
what is called “ goose-flesh.” Similar action of the muscles in 
the skin of a dog’s back causes the hair to stand on end. Mus- 
cular fibers are found in the walls of the stomach and intestines, 
and in the coatings of the blood-vessels, and their contraction is 
a part of the machinery of digestion and circulation. The act 
of swallowing is performed by muscular contraction in the gul- 
let. Minute muscles in the middle ear act when we give atten- 
tion to sounds. The modulations of the voice are produced by 
the contraction and relaxation of numerous small muscles. The 
eyeballs are moved by six sets of muscles. Minute muscles reg- 
ulate the amount of light admitted into the eye, and others 
adjust the parts of the eye to the different distances of objects. 
The heart is a muscle of peculiar construction, and the tongue is 
made up of several muscles covered with mucous membrane. 36 
LESSONS IN PHYSIOLOGY. 
2. Sizes and Shapes of Muscles. — While the longest muscle 
in the body is about two feet, the shortest is but a small 
fraction of an inch in length. In weight they vary from a few 
grains to several pounds. The most common form is spindle- 
shaped (fusiform) ; that is, large in the middle and tapering to 
each end. Some are fan-shaped (radiating), some like a feather 
consisting of fibers converging to one side of an axis (penniform), 
or to both sides of an axis (bipenniform). A few muscles are 
like circular bands, and when they contract diminish the size of 
the opening they surround; such are called sphincter muscles. 
3. How Muscles are named. — There are about five hundred 
distinct muscles in the human body, each having a special use, 
and all have been named and minutely described by anatomists. 
The names are usually derived from the Latin. These names 
were given to them when Latin was the language of the learned. 
Latin is to-day a common language among scientific men in all 
civilized countries. So you will find in English, French, and 
German works on Anatomy the same words used for names of 
most of the parts of the body. 
Muscles are named from: (1) their shape, as deltoid (like 
the Greek letter delta) ; (2) their location, as tibialis (near 
the tibia); (3) points of attachment, as sterno-cleido-mastoid, 
(sternum, clavicle and mastoid process); (4) their action, as 
flexors (bending), extensors (extending); (5) their divisions, 
as biceps (two-headed), triceps (three-headed). 
A few of the more important muscles are here mentioned. 
The occipito frontalis passes over the top of the head, and 
raises the skin over the eyes and moves the scalp. The tem- 
poral and the masseter raise the lower jaw, and are capable of 
closing the teeth very forcibly. Some wonderful feats are per- 
formed, lifting weights, holding out chairs, etc., by persons with 
strong jaws. The temporal muscle may be felt moving if you 
place your finger on the temple and work your jaws. In the 
same manner you may feel the contraction of the masseter by 
placing the fingers just below the cheek-bone. The sterno- 
cleido-mastoid has a long name, but it is an important muscle. 
It can be felt as a thick cord in the side of the neck. When GENERAL DESCRIPTION OF MUSCLES. 
37 
the head is turned to one side, it stands out as a ridge. When 
one acts alone it turns the head to one side. When both act 
together they bow the head. The pectoralis major on the breast 
pulls the arm forward. It is the principal muscle used in moving 
the wing of the bird, and is very large in the rapid-flying birds. 
The intercostals are small muscles between the ribs. They 
move the ribs in the act of breathing. The deltoid on the 
shoulder raises the arm. The biceps can be seen and felt con- 
tracting on the front of the arm when it is bent at the elbow. 
The triceps is on the opposite side, and straightens or extends 
the arm. The sartorius (tailor) is the longest muscle of the 
body, and passes from the outer side of the hip-bone to the 
inner side of the upper end of the tibia, and is used in crossing 
the leg, whence the name “ tailor’s muscle.” The gastrocnemius, 
one of the bulkiest muscles, forms mainly the calf of the leg. 
It raises the heel, and is one of the principal muscles used in 
walking and leaping. 
4. Attachments of Muscles. — They are usually attached to 
bones, or, rather, to the periosteum of the bone; but some- 
times to cartilage, to ligaments, to the skin, and to other mus- 
cles. In some cases they are attached directly by the muscular 
fibers, but usually by means of fibrous cords, or bands, called 
tendons. In some of the muscles of the limbs, the tendons are 
much longer than the muscles themselves. If you close your 
fist very tightly, you may observe cords standing out under the 
skin of the wrist. These are the tendons of the muscles which 
move the fingers. Here, for convenience, the power is placed 
at some distance from the part to be moved, the muscles which 
move the fingers lying in the forearm. Their tendons all pass 
under strong ligaments which encircle the wrist. If they were 
not thus held down, when the hand is bent and the fingers 
moved the tendons would be drawn away from the wrist. Sim- 
ilar ligaments hold the tendons down on the inner side of the 
fingers. In this respect the tendons are like ropes passing over 
pulleys. The direction of the force is changed. 
The rounded tendons we observe standing out under the 
skin in the arms and legs are called, in common language, 38 
LESSONS IN PHYSIOLOGY. 
leaders. In an animal they are generally called sinews. The 
ancient Greeks had but one word, neuron, for both tendons 
and nerves. They did not know that they were entirely dis- 
tinct and for widely different uses. Some people, even to-day, 
imagine that a man’s strength lies in his nerves, for they some- 
times speak of a muscular man as a “nervy man.” Tendons 
are not elastic, or at least very slightly so, but they are very 
flexible and tough. An animal when being dressed by the 
butcher is hung up by the tendons (“ ham-strings ”) of the 
legs. 
Tendons may be distinguished from nerves by their pearly 
and glistening appearance and by their greater strength. 
One tendon at least deserves special 
mention. It is called the Tendon of 
Achilles, is attached to the heel-bone, and 
is the combined tendon of the muscles of 
the calf of the leg. It is the thick cord 
you can feel behind the ankle. It is so 
named from the fabulous story of Achilles, 
the Greek hero, whose mother dipped him 
when a child in the river Styx and thus 
made him invulnerable, except in the part 
which she held in her hand and which did 
not get dipped. When he grew to be a 
man he was wounded in battle in this part 
of his body, and the wound caused his 
death. This tendon is sometimes too short 
and the heel is drawn up, the deformity 
being known as “club-foot.” In many 
cases it may be cured by cutting the ten- 
don beneath the skin with a peculiar instrument, in which case 
new fibrous material grows in to fill the gap, and the ten- 
don thus becomes longer. Children born with deformed limbs 
should as early as possible be examined by a competent sur- 
geon, as in many cases if taken in time the deformity can be 
removed. 
Fig. 7. — Lower Portion 
of the Leg, showing 
Tendon of Achilles. NATURE AND ACTIONS OF MUSCLES. 
39 
PRACTICAL ILLUSTRATIONS. 
1. Get the “hock-joint” of an ox, calf, or sheep from the butcher. This 
joint corresponds to the ankle-joint in man. These animals have a very long 
metatarsal hone, which raises the ankle a considerable distance from the ground. 
Imagine a man with one metatarsal hone, and it as long as the tibia, and that 
he walked on his toes instead of the sole of the foot, and you will have an 
arrangement similar to the hind-leg of a horse, ox, or sheep. The object in 
procuring this particular joint is that you may get a good idea of a tendon. The 
Tendon of Achilles, or a portion of it, may be shown attached to the heel-bone. 
Cut it across to show the structure and density. Observe how flexible, yet how 
strong. 
2. The tendons, with their attachments to muscles, may be best shown in 
the leg and foot of a rabbit. These animals are easily obtained in the winter 
from farmers’ boys in the country, and are usually found in the markets of the 
cities and towns. When the skin is removed, by pulling it from above down- 
ward, as you would take off a glove, an excellent view of the tendons and the 
ends of separate muscles is had. Note the glistening, pearly appearance. By 
separating a single tendon and pulling upon it, you may observe how the toe is 
drawn back. This can be shown, perhaps, better in the foot of a cat or dog. 
LESSON 8. 
Nature and Actions of Muscles. 
1. Structure. — If a piece of raw, lean meat (muscle) be 
examined with the unaided eye, it will appear to consist of 
layers of fibers which are not very distinct. If cut “ across the 
grain,” the surface appears in irregular masses, looking like the 
ends of bundles of fibers. Boiling separates the fibers some- 
what, so that we can easily split it into finer and still finer 
threads, until at last we arrive at a thread finer than the finest 
hair, which we cannot further divide. Before the microscope 
revealed the real structure of this thread, it was called the 
ultimate fiber, and in many books this term is still used, 
although, as we shall see, it is not the ultimate, or last division. 
If one of these fibers be placed under the microscope, and ex- 
amined by a high power, fine lines, ten thousand to the inch, 
running both across and lengthwise, may be seen, as it were, 40 
LESSONS IN PHYSIOLOGY. 
dividing it up into little squares, or blocks. Treated with cer- 
tain chemicals, it splits crosswise into discs, or plates, and with 
different treatment into rows of little blocks, like strings of 
beads. A transparent membrane covers the fiber, enclosing it 
as a sheath, or tube. These little blocks have been called mus- 
cle-cells, or sarcous elements; a row of them a fibril (little 
fiber). The tubular sheath is called the sarcolemma (flesh- 
rind), or myolemma (muscle-rind).1 The fibers are glued to- 
gether in small bundles, and these again into larger bundles, by 
a very fine cobweb-like tissue called perimysium (around the 
muscle). This tissue also forms a sheath for the entire muscle, 
blending at the ends into the tendon. 
All the muscles of the body which are under the control of 
the will, are constructed in this manner, and, from the appear- 
ance of the fibers under the microscope, are called striated, or 
striped muscles. The involuntary muscles are simpler in their 
structure, being made up of cells in the form of flat, tapering 
bands interlacing in all directions. The heart is not under the 
control of the will, yet it has the structure of a voluntary 
muscle. 
2. Composition. — The exact chemical composition of muscle 
is yet an unsolved problem. All that can be said is that it con- 
tains an albuminous substance called myosin, which seems to 
be peculiar to muscle. It is very probable that living muscle 
is chemically different from dead muscle ; in other words, the 
death of the muscle is a chemical change in its composition. It 
is known to all that soon after the death of an animal the mus- 
cles become stiff. This stiffness in a little while passes off and 
the muscles become relaxed as before. This stiffness must be 
due to a chemical change which is not well understood. 
3. How Muscles act. — Muscles produce motion by contrac- 
1 “It can be shown that a muscle-fiber, when recently taken from a living 
animal, must, in reality, be of a fluid, or, at least, of a semi-fluid nature. So 
that it is impossible to affirm that either the discoid or the fibrilloid structure 
actually exists in the muscle-fiber itself ; it must rather be assumed that both 
forms of structure are really the result of the application of reagents (chemicals), 
which solidify the originally fluid mass, and split it up in a longitudinal or trans- 
verse direction.” — Rosenthal, NATURE AND ACTIONS OF MUSCLES. 
41 
tion and relaxation. Contraction is a change of form in the 
muscle. It grows shorter and thicker, and thus pulls upon the 
part which is attached to it. There is a very slight change in 
bulk also; the contracted muscle is a very little smaller than 
before. Relaxation is the return to its original condition. 
Nearly every muscle has its antagonist; that is, one muscle by 
its contraction draws a part in one direction, another by its con- 
traction pulls it in an opposite direction. Thus the biceps and 
triceps of the arm are antagonists, the former bending the arm, 
the latter drawing it straight again. 
Muscles have no power to contract of themselves. They 
must be stimulated in some way. Ordinarily our muscles con- 
tract in obedience to our will, but this is only another way of 
saying that a stimulus passes from a nerve center in the brain 
through a nerve to the muscle. Separate a muscle from the 
nerve center and it will not contract unless stimulated in some 
manner. Mere currents in the air may be the stimulant; thus 
the muscles of a beef continue to twitch for some time after it 
is dressed. A sharp blow with a stick on a muscle, recently 
separated from a living animal, will cause contraction. Electric- 
ity and application of strong acids will cause contraction. In 
man and the higher animals this power to contract ceases in a 
few minutes after death, except in some cases of death by cer- 
tain diseases it may continue for an hour, or if powerful cur- 
rents of electricity be applied, contractions may be produced for 
an hour or longer. In the frog or snake it lasts much longer, 
and in the turtle contractions may be produced four days after 
death, or even longer. 
The stimulus need not be applied directly to a muscle. If 
we dissect out a portion of a nerve leading to a muscle, and 
apply the stimulus to that, contraction will take place in the 
muscle. This raises the question, Is the irritability in the mus- 
cle substance, or is it due to the nerves acting upon the muscle ? 
This is as yet an unsettled question among physiologists. It 
will be a difficult point to settle because every part of a muscle 
is supplied with filaments of nerves, and when we apply a stimu- 
lus to one we apply it also to the other. 42 
LESSONS IN PHYSIOLOGY. 
4. Voluntary and Involuntary Muscles. — Most of the striated 
muscles contract usually only in obedience to the will, and they 
are said to be voluntary muscles. All voluntary muscles, how- 
ever, act at times involuntarily. For example, we accident- 
ally touch a hot stove, the muscles contract and move the hand 
before we have time to exercise the will, or simultaneously with 
the consciousness of the pain. When we tickle the limbs of a 
sleeping person they move, although he is unconscious. The 
muscles of the eye-lids are partially under the control of the 
will; we wink unconsciously, yet for a time we can keep from 
winking. This involuntary action of voluntary muscles is a 
wise provision to keep us out of danger. (See Reflex Action 
in lessons on the Nervous System.) The non-striated muscles 
are without exception involuntary. Thus motions of the walls 
of the stomach and intestines go on, and the food is moved 
along in the digestive canal while we are all unconscious of any 
action. 
5. Relation of Muscles to Bones. — Muscles would be useless in 
the higher animals without bones, and bones would be useless 
in any animal without muscles. Taken together they are the 
locomotive and food-obtaining machinery of the body, as well as 
its means of defense. 
The long bones act as levers, and all the bones act as ful- 
crums for the muscles. A lever is an inflexible bar, or rod, 
which moves about a fixed point called a fulcrum. The force 
used to move a weight, or exert another force, is called the 
power. The load moved, or force produced, is called the weight. 
The power multiplied by the distance through which it 
moves, is equal to the weight multiplied by the distance it 
moves. This is the law of the lever. By this law what is 
gained in power is lost in time (or distance), and what is gained 
in time (or distance) is lost in power. Now the muscles fre- 
quently so act upon the bones that they gain in time (or dis- 
tance), but lose in power. To illustrate, place a five-pound 
weight in the hand, straighten the arm, and hold it out horizon- 
tally. To do this requires a muscular effort or power equal to 
about one hundred pounds. Now bend the arm at the elbow, NATURE AND ACTIONS OF MUSCLES. 
43 
and bring the weight over on your shoulder, at the same time 
placing your other hand on the biceps muscle. You observe 
that the muscle has only shortened itself a little, while the 
weight in your hand has moved through the fourth part of a 
very large circle. 
6. Strength of Muscles. — The strength of a muscle and the 
power it is capable of exerting are not the same. A muscle in 
itself is a soft, yielding mass which can be torn asunder without 
much force, yet the same muscle contracting in obedience to a 
stimulus from the nerves is capable of exerting very great 
power. By the hands alone, David L. Dowd of Springfield, 
Mass., in 1883, lifted 1442i pounds. W. B. Curtis of New York 
City, in 1868, by means of harness attached to his body, lifted 
the enormous weight of 3239 pounds. Insane persons, and 
patients in delirium, sometimes exert great power with their 
muscles. It seems that under an stimulus they have 
greater power than when called into action by the mere exercise 
of the will. Patients in convulsions have been known to tear 
some of the muscles of the limbs completely asunder by their 
rapid and forcible contraction. 
The power capable of being exerted by muscles is not in 
proportion to the size of the animal. A man can drag on a 
level surface nearly his own weight, while a horse cannot, under 
the same circumstances, drag more than two-thirds of his weight. 
Insects are, in proportion to their weight, the strongest of ani- 
mals. Some beetles have been known to drag forty times their 
own weight. 
The ability to lift heavy weights is no true test of a healthy 
person. Training and inherited peculiarities have much to do 
with it. A man may be healthy and long lived and yet have 
but comparatively little muscular power. The ability to pro- 
duce rapid motions is characteristic of some persons, and to lift 
or drag heavy weights is characteristic of others. The power 
in both cases may be greatly enhanced by proper training and 
practice. 44 
LESSONS IN PHYSIOLOGY. 
LESSON 9. 
Hygiene of Muscles. 
1. Exercise and Rest. — A healthy condition of the muscles, as 
well as of all other organs of the body, depends upon a proper 
alternation of exercise and rest. There is no absolute rest; that 
is, some part of the body is always in motion. When all motion 
ceases, life is at an end. But no particular set of muscles works 
constantly. The heart contracts seventy times in a minute, yet 
between the contractions there is a brief period of rest, and the 
total of these periods of rest is equal to about nine hours a day. 
In the act of respiration, which is continually going on, one set 
of muscles rests while another set works. Whenever, from de- 
rangement of the nervous system, which controls all muscular 
action, the heart beats more rapidly than usual, a corresponding 
lessening of activity follows. If the motion is excessive, exhaus- 
tion of its power and entire cessation of its motion take place. 
The same is true of the muscles of respiration. Undue activity 
is followed by undue inactivity. Thus, in a general sense, 
ceaseless activity is the law of our being, yet each particular 
organ, or set of muscles, must have their periods of inactivity. 
2. Exercise a Necessity. — As stated in our Introduction, 
physical life seems to consist of the constant birth, growth, 
and destruction of cells. The birth or creation of a cell im- 
plies the need of material to build it. The destruction of a 
cell implies the removal of the material which composed it. 
This importation of new material to build cells, and exporta- 
tion of old material, is favored by activity of the muscles; this 
activity causing an increased flow of blood to the muscle, the 
blood bringing the new material and removing the old. Action, 
then, is the law of animal life, action not only in the minute 
parts but in parts taken as a mass. The power of contraction 
is due to the life of a muscle; this life we have seen is the 
activity of the cells. There is thus a mutual necessity for 
action; the mass-motion producing activity in the cells, and 
the activity in the cells renders the mass-motion possible. HYGIENE OF MUSCLES. 
45 
The foregoing paragraph must not be construed as an argu- 
ment for materialism. When we say life consists of activity 
of the cells, we are simply stating the limitations of science. 
The power which causes this birth, growth, and destruction of 
cells is beyond our comprehension. It must be a power out- 
side of matter, and science cannot deal with it. This is in 
reality an argument for the existence of a God. 
3. Rest a Necessity. — While motion may be continual in the 
cells, it cannot be in the mass. We know that continual motion 
of a part exhausts it, and death is the result. This exhaustion 
seems to be simply the loss of power to create and destroy cells. 
Rest, then, is as absolutely necessary as exercise. 
4. Frequent Alternation of Exercise and Rest.—Long-continued 
exercise of any one part is not only disagreeable, but injurious. 
Try to hold a book at arm’s length for five minutes. Easy 
enough for the first quarter of a minute, it becomes really pain- 
ful at the end of a minute, and to hold it five minutes would 
be absolute torture. The muscles used in extending the arm 
are in a state of contraction the whole time, and they become 
wearied by the exertion. Contraction is not the normal state 
of a muscle. It has a certain tonicity, as it is called, or state 
of readiness to contract, but is soon exhausted by continued 
contraction. It is much easier to push the book out and draw 
it back rapidly for five minutes than to keep it out that long, 
because half of the time one set of muscles is working and 
another set is resting. For the same reason, walking is not so 
fatiguing as standing still. In walking, different sets of muscles 
are alternately brought into action; but in standing still, cer- 
tain muscles are required to be kept in a state of constant 
contraction to keep the body in an upright position. When a 
man is shot through the head, he falls instantly, because the 
bullet paralyzes a nerve center which controls the muscles, 
and those muscles which maintain the body upright immediately 
relax. 
Long-continued action of one set of muscles should be avoided. 
Persons whose occupation requires a sitting posture should im- 
prove every opportunity to stand upright, if it is but for a 46 
LESSONS IN PHYSIOLOGY. 
minute at a time. Where writing is to be done, it should not 
be done altogether in a sitting position. A high desk, where 
one can stand and write for a change, is a valuable hygienic aid 
to bookkeepers and others who write a great deal. On the 
other hand, persons whose occupation requires a standing posi- 
tion, should avail themselves of all opportunities of sitting 
down. Women, in their housekeeping duties, should contrive 
to do a part of their work sitting, as there is usually enough to 
do which must be done standing. When sitting or standing, a 
mere change in the position of the limbs, so as to bring the 
weight of the body upon a different place and sustain it by 
different muscles, will give relief and be beneficial. 
5. Kinds of Exercise. — In many cases a man’s occupation gives 
him the proper amount and variety of exercise. The farmer, 
for example, needs little or no exercise beyond that which his 
occupation compels him to take. He need only guard against 
straining and over-working his muscles. But persons of seden- 
tary occupations, or those whose occupations call for exercise of 
certain muscles to the exclusion of others, should take care that 
the muscles unused in their work should have exercise in some 
other way. 
Walking is one of the best forms of exercise for the majority 
of people, as it brings into action almost all of the muscles of 
the body. Persons, however, who have narrow and flat chests, 
and inherit consumption, should take such exercise as will bring 
into action the muscles of the arms, shoulders, back, and chest, 
and thus develop greater lung capacity. 
Horse-back riding is beneficial in many cases where the physi- 
cal strength is not great. It is largely a passive form of exer- 
cise, and benefits other organs than muscles by the shaking it 
gives them. If the horse does not have an easy gait, this shak- 
ing may be too violent. A great many muscles are, however, 
brought into action in the constant effort to maintain one’s 
equilibrium. It is a very suitable form of exercise for women 
under all ordinary circumstances. Carriage riding is more 
particularly suitable for invalids and very delicate persons. 
Boat rowing, sivimming, and skating, when not overdone, are HYGIENE OF MUSCLES. 
47 
valuable forms of outdoor exercise for those who can indulge 
in them. G-ymnastic exercises, such as the use of clubs, dumb- 
bells, ropes, poles, etc., have a proper place, but frequently are 
abused by those who are not trained to a proper gradation and 
moderation of the exercises. Outdoor games, such as croquet 
and lawn tennis are very beneficial, as there is scarcely any 
danger of over-indulgence. 
Running, leaping, boat racing, base-ball and foot-ball playing 
are apt to be injurious to many by being violent and prolonged. 
Running and leaping are more appropriate for children, since 
their bodies are light and dangers from falls and shocks cannot 
be so great. 
6. Violent Exercise should always be avoided. Straining the 
muscles is injurious, Lifting heavy weights is apt to overtax 
the muscles. Leaping may not injure a child, but in a heavy 
man the violent effort to raise the body and the sudden jar of 
lighting may prove serious, occasioning rupture of abdominal 
muscles or of some internal part. There is also danger of rup- 
tures in running, throwing and lifting weights. Long-continued 
exercise may prove serious by over-stimulating the action of the 
heart. Take, for example, the case of the girl who tried to 
excel her companions in jumping the rope the greatest number 
of times. Failure of the heart caused sudden death. 
If one would like to attempt feats of lifting, he should begin 
by lifting light weights, and very gradually increase them from 
day to day. The story is told of Milo, an ancient Greek, that 
he carried a calf every day until it grew to be an ox, and then 
killed it with a blow of his fist, and ate the whole of it in one 
day. The latter part of the story we cannot believe, but the 
first part is not incredible. 
7. Effects of Muscular Exercise on Other Organs. — One of the 
immediate effects of exercise of the muscles is an increased 
action of the heart, sending a greater amount of blood to the 
surface as well as an increased flow of blood through the partic- 
ular muscles exercised. “ The glow of exercise ” on the face 
is familiar to all. When not unduly prolonged this is benefi- 
cial to all the organs of the body. Respiration is increased, and 48 
LESSONS IN PHYSIOLOGY. 
more oxygen is taken in, and more carbonic acid gas thrown 
out; digestion is aided if the exercise be not severe and does 
not follow too soon after a full meal; the action of the liver, 
kidneys, and all the glands of the body is increased, and the 
brain and nervous system is beneficially stimulated. 
8. Best Time for Exercise. — One should not indulge except 
in the mildest form of exercise immediately after eating a hearty 
meal, as all the energies of the system are needed in digesting 
the food; neither is it good to exercise much just before eating. 
The morning is generally the best time for sedentary persons to 
take physical exercise, although gentle exercise before retiring 
will often insure sound sleep which might not otherwise be pos- 
sible. 
9. Other Favorable Conditions. — Exercise should be taken in 
pure air, out of doors always if the weather is good. Since, as 
we have seen, exercise increases respiration, it is the more essen- 
tial that the air we breathe should be fresh and pure. 
Exercise taken when the mind is cheerful is more beneficial 
than when the opposite is the case. It is not best to take exer- 
cise simply for the sake of the exercise. The mind should not 
dwell on the fact that we are exercising for our health. Some 
other motive should actuate us. Take a walk to enjoy the 
sunshine and fresh air, to hear the birds sing, or to see the 
sights of a city, to see a friend, to gather flowers, or to collect 
insects, minerals, or shells. It would be well if all business and 
professional men had an avocation as well as a vocation ; that is, 
that they had some side issue, some favorite study of nature 
which would take them out of doors in search of specimens, or 
for making observations of natural phenomena. A passion for 
hunting or fishing in professional and business men is often a 
means of prolonging their lives and insuring more effective 
work, as it sends them to the woods and fields, and compels 
them to take in a pleasant way the exercise and air which they 
greatly need. Even some mechanical avocation, as using tools 
in making trinkets, or in trying to invent some machine or 
mechanical device, followed in leisure hours, is beneficial in 
taking the mind from the routine of daily work, and bringing 
unused muscles into action. HYGIENE OF MUSCLES. 
49 
Hard work seldom kills people. It is worrying and fretting 
added to their work that takes men off in the prime of life or 
makes them old before their time. This point will be more 
fully discussed in the lesson on the Hygiene of the Nervous 
System. 
10. Effects of Alcohol on the Muscles. — The general nature and 
effects of alcohol and alcoholic drinks will be treated in a sepa- 
rate chapter, but it will be appropriate in this connection to note 
the special effect on the muscular system. All alcoholic drinks, 
as wine, beer, ale, whiskey, gin, rum, brandy, hard cider, etc., 
have a bad effect on the muscles when used for any considerable 
length of time, even when moderately indulged in. It was for- 
merly believed that alcohol increased a man’s strength, and it 
was the custom among farmers to serve out whiskey, or some 
other strong drink, to “harvest hands,” and during slavery- 
times many planters gave their slaves a daily ration of rum. 
Governments also issued rations of whiskey to soldiers and sail- 
ors, especially during active service. Even in these days many 
laboring-men in towns and cities think it absolutely necessary 
to have beer as regularly as their meals. Alcohol, indeed, 
apparently increases the strength, for it stimulates to greater 
exertion. It is like the spur and whip to the horse, making him 
put forth all his strength, but does not increase his strength. 
There may be rare occasions when a stimulant is needed to cause 
a man to use all his strength of body or mind for a brief period, 
that he may accomplish a certain task with the design of resting 
afterwards to make up the loss. Such occasions, however, do 
not occur to one in ten thousand persons; besides, in such cases, 
a milder and safer stimulant, as strong coffee, tea, or chocolate, 
will answer just as well, or better. 
Alcohol has its proper place among medicines, and may be 
employed to advantage in treating certain diseases, and even he 
the means of saving life in the hands of a skillful physician ; 
but as a beverage, or for every little ailment, its use brings more 
harm than good. 
A drunken man staggers, and speaks incoherently. Sometimes 
he sees double, and he imagines other persons are intoxicated. 50 
LESSONS IN PHYSIOLOGY. 
These peculiarities are explained by the fact that alcohol so 
affects the nerves that they lose control of the muscles. The 
muscles do not co-ordinate; that is, one set of muscles does not 
work in the proper alternation with another set, hence the man 
cannot walk straight, and cannot use tools with precision. The 
muscles of the tongue do not act in accordance with the will, 
and articulation is imperfect. The muscles that move the eye- 
balls do not work in harmony, and he sees separate images with 
the two eyes. The eyeballs roll unsteadily, hence the images 
he sees appear to stagger and have the effect of being drunk. 
But suppose a man uses alcohol moderately so that he is 
never visibly affected. Then the effect on the muscles is not so 
immediate, but in time will tell in loss of physical strength and 
power of endurance, because the digestive system is affected, 
and through it the nourishment of the muscles. Muscles which 
do not receive their proper nourishment degenerate and lose 
their natural tone and elasticity. This point will appear more 
apparent when we come to study the Digestive System. 
The statements in this work concerning the effects of alcohol 
are not the imagining of a fanatical reformer, but are based upon 
the experiments and observations of leading physicians and men 
of science. 
EXERCISES FOR REVIEW. 
1. Name the kinds of muscles as to volition. As to structure. 
2. Why are muscles sometimes called tubular tissues ? 
3. What is the use of tendons ? How distinguish tendons from nerves ? 
4. Write the names of six important muscles and locate them. 
5. Why should we take exercise ? When should we take exercise ? 
6. Why the need of rest ? 
7. Why are alcoholic beverages injurious to the muscular system ? Part IT. 
HOW THE BODY IS NOURISHED, OR THE NUTRI- 
TIVE APPARATUS. 
CHAPTER I. 
HOW THE FOOD IS PREPARED, OR THE DIGESTIVE SYSTEM. 
LESSON 10. 
From the Hand to the Stomach. 
1. The Mouth. — In most of the lower animals the mouth is 
used for the purpose of seizing the food, and in many for seizing 
and receiving only, as their food is swallowed whole. In the 
higher animals, including man, the food is masticated and mixed 
with saliva as a preliminary preparation for further digestion in 
the stomach and intestines. Man is more highly favored, being 
provided with two wonderful machines called hands, for seizing 
and conveying food to the mouth. In ancient times the hands, 
or simply the thumb and finger, were used alone for conveying 
all solid food to the mouth. Forks are a modern invention, and 
even now they are not used by the Chinese, who make use of 
two round sticks for this purpose. 
The mouth is the beginning of a canal, or tube, of varying 
size, called the alimentary canal, the entire length of which is 
over thirty feet, and includes the pharynx, esophagus, stomach 
and small and large intestines. These, with the teeth, salivary 
glands, liver, pancreas, and spleen, are usually described as organs 
of digestion. 52 
LESSONS IN PHYSIOLOGY. 
The tongue when at rest forms the principal part of the floor 
of the mouth; the hard palate, which is composed of parts of 
the superior maxillary and palate bones and is covered with 
mucous membrane, forms the roof. The back part of the mouth 
is called the fauces. It has an opening into the pharynx; and 
from the top of this opening, like a curtain, hangs the uvula, or 
hanging palate, and on either side, beneath the mucous mem- 
brane, lie the tonsils. These are peculiar glands whose use is 
not certainly known. They sometimes become troublesome by 
growing unnaturally large, and may be cut out by the surgeon 
without serious results. Inflammation of this part is known as 
quinsy or tonsilitis. 
The lips form the front boundary, and the cheeks the sides of 
the mouth. The cheeks are composed mainly of a large, flat 
muscle called the buccinator (trumpeter, because used in blow- 
ing a trumpet). The contraction of this muscle, with the aid 
of the tongue, keeps the food between the teeth in the act of 
mastication. 
2. The Teeth Classified. — As to duration, teetli are of two 
kinds: (1) temporary, deciduous, or milk teeth, twenty in num- 
ber, appearing between the seventh month and close of the 
second year; (2) the permanent teeth, thirty-two in number, 
appearing usually between the fifth and twenty-first years. As 
to form and use, there are four kinds of teeth: (1) incisors, 
four in front part of each jaw, thin, broad, and sharp, with one 
root, and adapted for cutting; (2) canines (upper usually called 
“ eye-teeth,” lower “ stomach teeth ”), two in each jaw, one on 
each side of the incisors, sharp, conical, with single, long roots, 
and adapted for tearing; (3) bicuspids, or premolars, four in 
each jaw, two behind each canine, having two cusps or points, 
with usually a single root; (4) molars, six in each jaw, back of 
the bicuspids, the largest of the teeth, have several cusps, and 
from two to five roots (generally three in the upper teeth, and 
two in the lower), and adapted for crushing and grinding. The 
third molar is called the wisdom tooth, because it usually does not 
appear until near the age of maturity. The canine teeth (named 
from canis, a dog) are much elongated in the dog and cat and FROM THE HAND TO THE STOMACH. 
53 
some other animals, and are called tusks, or “ tushes.” They are 
useful in these animals in seizing their prey. 
Of the temporary teeth there are four incisors, two canines, 
and four molars in each jaw. 
V, A, N, Veins, Arteries, and Nerves of the Teeth. The root of one tooth in each jaw 
is cut vertically to show the cavity and the blood-vessels, etc., within it. 1 to 8, 
Permanent Teeth. 
Fig. 8. — Section of the Jaws. Right Side. 
3. Structure of the Teeth. — Each tooth consists of a crown, 
that part above the gums ; a root, or fang, that part within 
the bone; and a slightly constricted portion between root and 
crown, and covered by the gums, called the necJc. 
The entire tooth contains a cavity which during life is filled 54 
LESSONS IN PHYSIOLOGY. 
with a soft substance called dental pulp. Each tooth has a 
vein, an artery, and a nerve which enter at the point of the root 
and branch out through the dental pulp. The body of the 
tooth, both crown and root, consists of a dense, white substance 
harder than bone, called dentine. Under the microscope it is 
seen to consist of many minute, branching tubes (dental tubuli) 
radiating from the pulp cavity outward, with a substance 
between, called intertubular tissue. The dentine is similar to 
bone in composition, but has a greater proportion of earthy 
matter. The crown of the tooth is covered with a very hard 
substance, called enamel. It is thickest at the top of the crown 
and gets thinner towards the neck, where it disappears. It is 
shown by the microscope to consist of minute, hexagonal rods 
lying parallel to each other and pointing towards the dentine. 
It is the hardest substance in the organic world and one of the 
most durable. It is harder than iron and most metals. It is 
composed of 96.5 per cent earthy matter. The root of the tooth 
is covered with a substance closely resembling bone in compo- 
sition and structure. It is called cement, crusta petrosa, or 
cortical substance. 
4. Development of the Teeth. — The time of eruption of the 
teeth varies considerably, but by comparing a great many cases 
the following average time has been made out: — 
For the temporary set: The seventh month, two middle 
incisors; ninth month, two lateral incisors; twelfth month, first 
molars; eighteenth month, canines; twenty-fourth month, last 
molars. For the permanent set: Between sixth and seventh 
year, first molars; seventh year, two middle incisors; eighth 
year, two lateral incisors; ninth year, first bicuspids; tenth year, 
second bicuspids; eleventh to twelfth year, canines; twelfth 
to thirteenth year, second molars; seventeenth to twenty-first 
year, wisdom teeth. 
The permanent teeth are formed beneath the temporary ones, 
and in their growth push against them, causing the roots of the 
latter to be absorbed. Sometimes, however, the temporary teeth 
do not become absorbed fast enough, and the permanent teeth 
grow out to one side, producing an unsightly irregularity. The FROM THE HAND TO THE STOMACH. 
55 
temporary teeth should be watched and, if necessary, removed 
by the dentist before the permanent teeth are too far along. 
5. Peculiarities of the Teeth. — Some persons have teeth natu- 
rally so good that they never decay, while the teeth of others 
decay even before they have reached their growth. Many theo- 
ries have been advanced to explain this early decay of the teeth, 
but none are satisfactory. Decayed teeth are found among all 
races and nations of people, but perhaps more frequently among 
the highly civilized. One of the most reasonable theories for 
the early decay of teeth among civilized people is that they do 
not use the teeth enough, the arts of cooking and preparing the 
food dispensing with the necessity of much mastication. But 
whatever the cause of their decay, experience shows that proper 
care of teeth will make them last longer. 
Teeth may be extracted and placed back in the jaw so that 
they will grow tight again, and may even be transferred from 
one person’s jaw to that of another. Modern dentists have 
achieved great perfection in the art of preserving and replac- 
ing teeth that have begun to decay. For the special care of 
the teeth, see Hygiene of Digestion. 
6. Uses of the Teeth. — Every child knows that the teeth are 
for the purpose of dividing the food and preparing it for swal- 
lowing. But they have other uses. In many animals they are 
for defence and for securing food. In man they serve a nobler 
purpose. They aid greatly in articulating and forming the 
sounds of our language. Certain consonant sounds are called 
dentals because made by the help of the teeth. They also add 
to the beauty of the face. 
7. The Salivary Glands.— These are small bodies which secrete 
— that is, manufacture from the materials brought by the blood 
— the saliva, which bears such an important part in digestion. 
There are three of these glands. The largest, called the parotid 
(near the ear), is beneath the skin, just in front of the ear, 
around the lower jaw. Its secretion is poured into the mouth 
through a small tube called Stensoris duct, which opens oppo- 
site the second molar tooth of the upper jaw. The next largest 
is the submaxillary, lying below the angle of the lower jaw. 56 
LESSONS IN PHYSIOLOGY. 
Its duct opens in the floor of the mouth, and is called Wharton's 
duct. The sublingual, the smallest, lies beneath the tongue, and 
opens by a number of ducts (from eight to twenty), called ducts 
of Rivinianus. 
These glands consist of many small lobules, like bunches of 
grapes, each of which is made up of numerous small vesicles 
(little bags), each with a tube which joins others, and finally 
unites in the main tube or duct. Can you imagine a great 
number of little rooms, each with very thin walls, through 
which material which has passed through the walls of the 
blood-vessels also, passes and there undergoes a chemical change, 
forming a new substance, which passes out of these rooms 
through narrow passage-ways, and finally into one larger pas- 
sage, and from thence into a chamber many times as large. If 
you can, you have a picture of what takes place in the salivary 
glands. The fluid manufactured by these glands becomes mixed 
with the mucus from the mucous membrane of the mouth, and 
is then called saliva. It is a clear liquid, slightly sticky, readily 
frothing, that is, gathering bubbles of air, and is composed 
mainly of water, but contains a peculiar substance which is found 
nowhere else in the body, and is called ptyalin. This is one 
of the organic “ferments,” a name given to certain substances 
which act chemically upon other substances and change their 
nature, that is, actually decompose them and recombine their 
elements to form a new substance. The use of ptyalin is 
to convert the starch of the food into sugar. We shall learn 
of other “ferments ” before we get through the book. 
8. Other Uses of Saliva. — Besides th‘e principal function of 
changing starch to sugar, the saliva has other and important uses. 
(1) It moistens the food, rendering it: (a) softer and thus more 
easily masticated; (5) more easily swallowed; (c) so it may be 
tasted. (2) It moistens the mouth, pharynx, and esophagus: 
(a~) protecting them from injury by the food; (b) making 
articulation easier. (3) It entangles hubbies of air and carries 
them to the stomach, a certain amount of oxygen being neces- 
sary for digestion. 
9. Digestion in the Mouth. — The food does not remain long FROM THE HAND TO THE STOMACH. 
57 
enough in the mouth to undergo more than a slight change. It 
is reduced to a finer state and mixed with the saliva which acts 
further when it has reached the stomach and intestines, but a 
slight amount of starch is changed to sugar even in the mouth. 
Absorption, or the passage of fluids into the blood-vessels, is 
an important part of the digestive process. A certain amount 
of the food is absorbed in the mouth. A little of the Avater 
containing sugar and salts in solution is absorbed directly into 
the blood-vessels. Poisonous substances may be absorbed from 
the mouth, and in quantity sufficient in some cases to produce 
death. If a drop or two of prussic acid he placed on the tongue, 
or on the mucous membrane lining the mouth, death occurs in 
a few minutes, although not a particle of it reaches the stomach. 
Boys who take their first chew of tobacco learn in a disagree- 
able manner that the entire system may be affected by simply 
placing certain substances in the mouth. 
10. The Pharynx is a short, wide portion of the alimentary 
canal which receives the food from the mouth and passes it into 
the esophagus. It is composed of muscles, some of which run 
with the fibers up and down, and some with the fibers circularly. 
T j is lined with a mucous membrane, continuous with that of 
the mouth and esophagus. There are seven openings from the 
pharynx; one to the mouth, one to the esophagus, one to the 
larynx, or beginning of the windpipe, two to the nose cavities, 
and two to the Eustachian tubes, which lead to the middle ear. 
We have no longer control of the food when it has passed 
into the pharynx, as all the muscles of the alimentary canal, 
except those of the mouth, are involuntary. The length of the 
pharynx is about four inches. 
11. The Esophagus, or gullet, is the name of the tube which 
extends from the pharynx to the stomach. It is about nine 
inches in length, and lies behind the windpipe, the heart, and 
the lungs, and passes through the diaphragm or muscular parti- 
tion dividing the cavity of the thorax from the abdomen. Its 
walls are elastic and lie collapsed when no food or drink is 
passing. The outer coat or wall is made up of two layers of 
muscular fibers, the outer of which run up and down, the 58 
LESSONS IN PHYSIOLOGY. 
inner, circularly. The middle coat is a layer of loose tissue, 
called the cellular or submucous coat. The inner coat is a 
mucous membrane, continuous with that which lines the entire 
alimentary canal. 
When a portion of food enters the esophagus, the muscles, 
one ring after another, contract behind it and thus force it along 
to the stomach. These muscles act with considerable force. 
Some one tried a singular experiment. He tied a ball to a 
string which passed over a pulley and had a weight fastened to 
the other end. Forcing the ball down the throat of a dog, he 
found that the esophagus could pull the ball with sufficient 
force to lift nearly half a pound. 
12. (1) In this lesson we have described the organs which 
perform three important acts in the process of digestion: (a) 
Mastication, or the grinding of the food; (b) Insalivation, or the 
mingling of the food with saliva ; and (c) Deglutition, or the act 
of swallowing. (2) We have learned that one of the important 
chemical changes which food must undergo before it can enter 
the system has been commenced: The conversion of starch to 
sugar. (3) We have learned that absorption commences even 
in the mouth. 
PRACTICAL ILLUSTRATIONS. 
1. Procure a human tooth from a dentist. Fasten it in a clamp, or into a 
hole in a piece of wood, and grind it down on the side nearly half way to the 
center on a coarse grindstone. Then rub it on a fine whetstone until the surface 
is smooth. Then brush it clean in water. The cut surface will show in a general 
way the structure of the tooth. The dentine, enamel, and cement will have a 
slightly different appearance, and the relative proportions of each can he seen. 
To show the minute structure would not be practicable, as an exceedingly thin 
section and a good microscope would he necessary. 
2. Grate or scrape a potato. Rub with water on a piece of muslin stretched 
over a vessel of any kind. The milky looking fluid that passes through the 
cloth is water mixed with undissolved starch. Pour the contents of the vessel 
into a glass tumbler, and let stand for an hour. You will observe that the starch 
settles to the bottom ; and you can by care pour off the water, leaving the starch 
in the bottom. Turn out the wet starch on a piece of blotting paper. In a little 
while the starch will he dry and appear as a fine, white powder. 
3. Put a little of the dry starch in a bottle, and add a quantity of saliva, 
which you must obtain from your mouth after thoroughly rinsing it out with THE STOMACH. 
59 
water. By working your jaws and the muscles of your face vigorously for a 
minute the flow of saliva will be increased. Let the mixture of starch and saliva 
stand in a warm place for two hours. Test it for grape sugar as follows : — 
Procure a small lump of sulphate of copper (blue vitriol, or blue stone). Any 
druggist will give you enough for the purpose. Dissolve it in clear water. Por 
a few cents the druggist will make for you an ounce of solution of potassium 
hydrate (caustic potash). Now place a little of the saliva and starch mixture in 
a large iron (or tinware) spoon, add to it about ten drops of the caustic potash 
solution, and then two or three drops of the sulphate of copper solution. Then 
hold the spoon over the chimney of a large lamp until the mixture boils, which 
it ought to do in a few minutes. The liquid, which was at first a bluish white, 
should, if grape sugar be present, turn to a brick-red color. This is a chemical 
test for grape sugar, and demonstrates that the starch has been converted into 
sugar by the action of the saliva. This is an interesting experiment, and can be 
made successful if proper care be taken. 
4. As preliminary to the succeeding lesson, and partly applicable to the 
foregoing, perform the following experiment to illustrate absorption through 
membranes. 
Procure a fresh egg with an unbroken shell. By careful tapping on the table 
crack the shell at the small end, pick off the broken pieces, taking care not to 
break the thin membrane just within the shell. If you break or tear this mem- 
brane, you must try again on another egg. After removing about a square inch 
of shell make a small hole through shell and membrane in the opposite end of 
the egg, taking care to keep the egg with this hole up so that the contents of the 
egg cannot escape. Now fix the egg on a support, so that the part exposing the 
membrane will be immersed in water. This can be done either by using a bottle 
with a mouth just wide enough to allow the egg to stand upright in the neck 
without falling into the bottle, or, if this is not convenient, you can use a tumbler 
even full of water with a pasteboard cover, and a hole cut in the latter just large 
enough to hold the egg and allow the end to dip in the water. In the course of 
an hour or less you will see the contents of the egg rising through the hole in 
the upper end. A sufficient quantity of water has been absorbed through the 
membrane to force the contents out at the hole. 
LESSON 11. 
The Stomach. 
1. It is a common notion that digestion is carried on alto- 
gether in the stomach. But as we shall see, only a part of the 
digestive process takes place in this part of the alimentary 
canal. 60 
LESSONS IN PHYSIOLOGY. 
The stomach is a pear-shaped bag or enlargement of the 
alimentary canal, lying in the upper and mainly in the left part 
of the abdominal cavity. Its position is more nearly vertical 
when the body is in an upright position than is usually repre- 
sented in pictures. It varies much in size in different indi- 
viduals, and also according to the amount of its contents. 
When moderately full, its average is twelve inches in length, 
four inches in breadth, and two inches in thickness, and holds 
about three pints. The left end projects beyond the entrance 
of the esophagus, and is called the f undus. The opposite or 
smaller end is called the pyloric extremity. The place where 
the esophagus ends is called the cardiac, or heart orifice; and 
the entrance to the intestine below is called the pyloric orifice. 
This opening is guarded by a kind of valve formed by a fold of 
the mucous lining, called the pylorus, or gate-keeper. 
The walls of the stomach consist of four coats: (1) The 
outer, or serous coat, is a portion of the peritoneum, which lines 
the abdominal cavity, and covers all the organs within it, and 
which will be more fully described under the Secretory System. 
(2) Beneath this is a muscular coat, some of the fibers of 
which run lengthwise, and some circularly, and some diagonally. 
(3) Next is a cellular, or submucous coat, like that which is 
found beneath the mucous membrane throughout the alimentary 
canal. (4) The inner coat is the mucous membrane continuous 
with that of the esophagus and intestines. This mucous mem- 
brane lies in many folds or wrinkles, which greatly increases its 
surface. It contains many small depressions called alveoli, at 
the bottom of which appear orifices of short tubes called gastric 
follicles. From some of these comes mucous; from others, 
gastric juice, which is the peculiar product of the lining of the 
stomach, as saliva is of the salivary glands. 
2. The Gastric Juice is a clear liquid consisting mainly of 
water with a small proportion of an acid and a peculiar ferment 
called pepsin. This ferment possesses the power of changing 
albuminous substances into albuminose, or as it is sometimes put, 
converting proteids into peptones. To make this statement clear 
it is necessary to know that albuminous substances, or proteids, THE STOMACH. 
61 
are those which contain nitrogen (hence called also nitrogenous) 
and are chemically similar to albumen. The white of an egg is 
almost pure albumen. This class of substances exists in eggs, 
lean meat, milk, grains, and in many vegetable seeds and nuts. 
Different varieties are produced from different articles, as casein 
from milk, fibrin from meat, gluten from grains, and legumin 
from beans and peas. Albuminous substances, or as they are 
sometimes called “ albuminoids,” are not soluble in water, and 
hence cannot be absorbed. Albummose, or peptone, is soluble and 
is readily absorbed. 
Grastric juice has no effect on starch, sugar, nor fats. Its sole 
office is to convert the albuminous portions of the food into a 
soluble form. Fat meat, or the unrendered fat of animals, is 
properly adipose tissue. It consists of a net-work of fibers en- 
closing the fat proper. While the gastric juice does not act 
upon the fat, it does dissolve this fibrous net-work, as it is of an 
albuminous nature, and releases the fat. 
3. Digestion in the Stomach. — The process which the food un- 
dergoes in the stomach is called chymification ; that is, the making 
of chyme. This is a word derived from the Greek and meaning 
“ juice.” It is applied to the food in the stomach after it has 
been thoroughly mixed and dissolved, or reduced to a semi-fluid 
mass. This is accomplished by two different agencies, mechani- 
cal and chemical: (1) The contraction of the muscular walls 
keeps the contents continually rolling about, passing from one 
end to the other and back again many times. This motion is 
called peristaltic (wrapping up) or vermicular (worm-like), as 
it has the appearance of a worm crawling. The food is thus 
“ churned,” and thoroughly mixed and broken up. The pylorus 
permits only a portion of the fluid contents to pass through 
unless the substance be some indigestible body, as a button or 
coin, which may have been swallowed. This may force its way 
through the gate into the intestines. (2) The contents of the 
stomach are by the churning action thoroughly mixed with two 
fluids which are capable of exerting chemical action on certain 
parts of the food. These fluids are gastric juice and saliva, but 
as the former is an acid fluid and the latter an alkaline fluid, 62 
LESSONS IN PHYSIOLOGY. 
they cannot act in each other’s presence unless one be greater 
in quantity or stronger than the other. The gastric juice is the 
stronger in this case, and prevents the saliva acting unless in 
the central part of a bolus, or mass of food, where it has not yet 
penetrated. The action of the saliva although mainly suspended 
in the stomach is renewed in the intestine. 
Chymification, or stomach digestion, requires from one to five 
hours or more, varying according to the nature and quantity 
of the food. Thus, according to Dr. Beaumont’s observations, 
boiled rice was digested in one hour, while boiled cabbage 
required four hours, and roast pork five and one-fourth hours. 
4. Why does not the Stomach digest itself since it is composed 
of albuminous matter, and gastric juice dissolves such readily ? 
This is a question often asked, and it is one difficult to answer. 
The probability is that the stomach does digest itself to some 
extent, and is renewed by the rapid growth of new cells. This 
view is favored by the fact that in some cases of sudden death 
the walls of the stomach are found, on post mortem examina- 
tion, to be partially digested. Besides, gastric juice is not pro- 
duced in any quantity except when food is in the stomach, and 
then it is rapidly absorbed by the food. The mucus, which is 
at the same time poured out in abundance, also, doubtless, pre- 
vents the action of the gastric juice on the walls of the stomach. 
5. Absorption from the Stomach. — During the process of chymi- 
fication, a considerable part of the fluid contents of the stomach 
passes directly into the blood, through the mucous membrane 
and the walls of the blood-vessels. Much of the water, some 
of the sugar, and albuminose are absorbed as they come in con- 
tact with the mucous membrane. Fats and albuminous matter 
and starch are not absorbed, but pass on to the intestine to be 
acted upon there. Poisons and medicines are absorbed, should 
they be taken with the food, but more rapidly if taken when 
the stomach is empty. 
6. Alexis St. Martin.—In the year 1822 a young soldier named 
Alexis St. Martin, a Canadian by birth, but serving in the 
United States army, was wounded by the accidental discharge 
of a gun. Dr. Beaumont, the army surgeon who attended him, THE STOMACH. 
63 
found the food which the man had eaten an hour before, issuing 
in a half-digested state from the wound in his side. In time 
the wound healed, but it was found that the injured part of the 
walls of the stomach, instead of reuniting, grew fast to the 
edges of the wound in the abdominal wall, leaving an opening 
two and a half inches in circumference, through which the 
interior of the stomach could be seen, and the contents taken 
out for examination at any time. 
Dr. Beaumont wished to improve this rare opportunity to 
study the processes of digestion, and so kept the patient a long 
time and tried many experiments upon him. He learned much 
that was interesting and valuable concerning stomach digestion. 
Since that time many observations have been made upon living 
animals by cutting through to the interior of the stomach, and 
sewing its wails to the abdominal walls until they united, thus 
forming by intention what was accidental in the case of St. 
Martin. 
There have been cases, also, where surgeons have been com- 
pelled to make similar openings in the human stomach for the 
purpose of introducing food in case of closure of the esophagus. 
In such cases digestion was not perfect because the patient was 
deprived of the saliva. A medical journal not long ago gave 
an account of a German physician who constructed an artificial 
esophagus which worked admirably. A boy had swallowed 
some caustic poison which destroyed the lining of the esophagus, 
and when it healed its walls had grown together, and the boy 
would have starved, had not an opening been made in the 
stomach. In order that the boy might get the benefit of the 
saliva, and enjoy the taste of his food, the surgeon fixed a 
rubber tube with a funnel shaped extremity long enough to 
reach from the stomach to the mouth. Fastening one end into 
the opening in the stomach, the boy could chew his food, trans- 
fer it from his mouth to the rubber tube, and allow it to pass 
to the stomach. This seems like a marvelous tale, but it is no 
more wonderful than many other feats of modern surgeons. 
7. Circumstance's affecting Stomach Digestion. — The stomach 
appears to act better upon a large than upon a small quantity 64 
LESSONS IN PHYSIOLOGY. 
of food; hence food that is somewhat bulky is better than food 
highly concentrated, and two or three good meals in twenty-four 
hours are better than many small ones. The stomach seems 
to have a tendency to act periodically. If one is accustomed to 
meals at the same hour every day, and then changes the time, 
digestion is not so perfect. The stomach, like every other 
organ, needs rest; hence, eating at short intervals, so as to keep 
food all the time in the stomach, is very unfavorable to diges- 
tion. 
Strong emotions, as anger, fright, grief, excessive joy, and 
anxiety, check digestion. A cheerful and contented state of 
mind favors digestion. Digestion proceeds most rapidly when 
the temperature of the stomach is about a hundred degrees 
Fahrenheit. Large quantities of ice-water or very cold food 
will lower the temperature, and arrest digestion. The normal 
temperature of the stomach is, however, soon regained after 
cold fluids enter it. Ice-water and ice-cream are frequently 
denounced as very bad for the stomach; but if one becomes 
accustomed to the former, and indulges moderately in the latter, 
no harm results in the majority of cases. When the body is 
heated by exercise, a quantity of an ice-cold drink may prove 
injurious or even fatal, by the sudden shock to the nervous 
system. 
Digestion is not quite so rapid during sleep, because the cir- 
culation of the blood is not so complete, and the nerve force of 
the system is less active. A hearty meal just before retiring 
usually causes disagreeable dreams. Healthy children and ani- 
mals, however, generally go to sleep after eating, and their 
digestion appears to be perfect. It is probably true, that while 
digestion may proceed more slowly during sleep, it is none the 
less perfect, and beneficial to the system. A small quantity of 
food eaten before retiring frequently favors sound sleep. 
Exercise, if severe, immediately after eating is unfavorable; 
but gentle exercise, by increasing the flow of the blood from 
the heart to the extremities of the blood-vessels, is favorable to 
digestion. THE STOMACH. 
65 
PRACTICAL ILLUSTRATIONS. 
1. Get a piece of the stomach of an ox. Wash it thoroughly, and boil it for 
an hour or more. The inner coat will show the elevations and depressions which 
increase its absorbing surface. The mucous coat can be separated from the 
muscular. 
2. The stomach of a pig resembles, in shape and size, the human stomach 
very closely. If one can be procured, it will be interesting to have it prepared 
for exhibiting to a class. Cut a slit in the side sufficiently large to enable you 
to turn it inside out. Then wash it thoroughly to remove the mucus and food, 
and turn it right side out again. Keep in water until ready to exhibit. Show 
the mucous lining by turning it partly inside out. Note the thickness of its walls, 
and how easily they may be distended. 
[It must be borne in mind always that many points cannot be demonstrated 
without a great deal of careful preparation. For example: if one should dissect 
out the main arteries that supply the stomach with blood, and inject into these 
a mixture of plaster of Paris and red lead, a beautiful illustration of the general 
blood supply of the stomach would appear. The fluid would fill and distend all 
except the most minute of the arteries, and solidifying there would show their 
number and positions very plainly. Further, if certain finer coloring fluids were 
injected into the blood-vessels, then a small portion of the stomach be hardened 
by soaking in certain liquids, then cut into exceedingly thin sections by a micro- 
tome (machine for cutting thin sections), and placed under the microscope, a 
beautiful exhibit of the capillary net-work of the blood-vessels in the mucous and 
cellular coat would appear. But these experiments require skill and patience and 
the use of material beyond the reach of the ordinary strident and teacher. They 
are mentioned here that the pupil may know how the anatomist and physiologist 
obtain the knowledge given in works on the subject.] 
LESSON 12. 
The Intestines. 
1. The Small Intestine. — When the chyme leaves the stomach 
through the pyloric orifice, it enters the small intestine, which 
is a tube about twenty feet in length lying coiled in the central 
part of the abdominal cavity. The first part of it, about ten 
inches in length, is called the duodenum. It extends from the 
stomach first upward, then backward and toward the right, then 66 
LESSONS IN PHYSIOLOGY, 
to the left in front of 
the spinal column, and 
ends at a point opposite 
the second lumbar verte- 
bra. 
The next division is 
called the jejunum (empty, 
because found so after 
death). This portion is 
about seven feet in length, 
and a little smaller than 
the duodenum. The third 
division is called the 
ileum (to twist). It is 
about twelve feet in 
length. These divisions 
are of little importance, 
as the structure and size 
are similar throughout the 
small intestine. 
2. The Large Intestine. 
— This portion of the 
alimentary canal, about 
five feet in length, is a 
continuation of the small 
intestine, but much larger 
in diameter. It does not 
begin simply by an en- 
largement of the small 
intestine, but is like a 
separate tube with the 
upper end closed, and 
the small intestine, like 
a smaller tube, entering 
at a point about two and 
a half inches from the 
end. This closed end, or 
Fig. 9. — Alimentary Canal. 
10, Uvula; 9, Fauces; 8, Tonsils; 14, Esopha- 
gus ; 21, Cardiac orifice; 16, Stomach; 
22, Pyloric orifice; 23, Duodenum; 27, Gall 
bladder; 29, 30, Hepatic duct; 26, Cystic 
duct; 3i, Common duct of the bile; 33, Pan- 
creatic duct; 41, Coecum; 43, Ascending 
colon; 45, Transverse colon; 47, Descending 
colon; 47,48,49, Sigmoid flexure of the colon; 
50, Rectum; 36, Ileum; 25, Jejunum; 40, Ileo- 
ccecal valve; 42, Vermiform appendix. The 
advanced student of anatomy may name the 
parts opposite the numbers not mentioned 
here. THE INTESTINES. 
67 
part above the entrance of the small intestine, is called the 
ccecum (blind). At the closed end of the ccecum is a small tube 
about as thick as a goose quill, and from three to six inches 
long. No use is known for this vermiform (worm-like) appendix, 
as it is called. Sometimes cherry stones, or other indigestible 
objects which may be swallowed with the food, find lodgement 
in this tube, and result in serious inflammation of the intestine. 
Swallowing cherry stones and other hard seeds of fruits is a bad 
practice. 
The colon is the next portion of the large intestine. It nearly 
surrounds the small intestine, the different portions taking 
different names from their positions. There is thus (1) the 
ascending colon, on the right side; (2) the hepatic flexure, or 
bend near the liver; (3) the transverse colon; (4) the splenic 
flexure, or bend near the spleen; (5) the descending colon, on 
the left side; and (6) the sigmoid (S-shaped) flexure, where it 
joins the rectum (straight), which is the last portion of the large 
intestine. 
3. Structure of the Intestines. — Like the stomach, the intes- 
tines throughout consist of four coats, — serous, muscular, cellular, 
and mucous. The mucous and cellular coats in the small intes- 
tine are wrinkled by numerous folds, called valvulce eonniventes. 
These are covered with minute projections, as thickly placed as 
the fibers in a piece of velvet. These projections are called 
villi (singular, villus, a tuft of hair). The surface for absorp- 
tion is thus enormously increased. Each villus contains the 
termination of a vein, an artery, and a lacteal. The latter 
will be more fully described under the Circulatory System. The 
mucous coat contains also various small glands, which secrete 
the intestinal juice. 
4. Before we discuss Digestion in the Intestines, we must first 
describe certain organs which lie outside of the alimentary canal, 
since they furnish fluids which play an important part in this 
digestion. 68 
LESSONS IN PHYSIOLOGY. 
LESSON 13. 
The Liver, Pancreas, and Spleen. 
1. General Description of the Liver. — A gland is an organ 
which either separates materials from the blood, or manufactures 
certain fluids from the elements furnished by the blood, or 
modifies fluids which pass through it. The liver is the largest 
gland in the body. It lies mainly in the right and upper por- 
tion of the abdominal cavity. Its length from side to side is 
from ten to twelve inches, its breadth from before backward is 
from six to seven inches, and its thickness from above down- 
ward is about three inches. It weighs in an adult three or four 
pounds. The number 5 prevails in the parts and appendages of 
the liver. It has five ligaments, or folds of the peritoneum, 
which hold it in place; five lobes, or divisions; five fissures, or 
furrows, on its under surface; and five different vessels, or sets 
of tubes, carrying material to and from it. 
2. Structure of the Liver. — The surface is covered with a 
thin membrane, being a continuation of the peritoneum, which 
lines the abdominal cavity, and covers all the organs within it. 
To the unaided eye its substance, when cut through, appears as 
a soft, semi-solid mass, with tubes of varying sizes scattered here 
and there. A careful examination with the microscope reveals 
the fact that all of these tubes continue to divide and subdivide, 
until they finally terminate in a fine net-work of minute vessels. 
The terminations of these vessels is in and between little masses 
of cells called lobules, the cells and vessels being held together 
by areolar (fibrous) tissue. Branches of the nerves also pene- 
trate to every part. In these lobules, or collections of cells and 
tubes, important work is carried on, as the liver is one of the 
greatest of the laboratories in this wonderful house of ours. 
3. The Vessels of the Liver are important, and deserve a 
partial description: (1) The portal vein is made up of branches 
from the stomach, spleen, and intestines. It enters the liver, 
and divides and subdivides until it terminates in the net-work 
above described. It carries during digestion materials absorbed THE LIVER, PANCREAS, AND SPLEEN. 
69 
from the stomach and intestines, some of which undergo impor- 
tant changes in the liver. (2) The hepatic artery supplies the 
liver with pure blood, just as every other organ is supplied. 
(3) The hepatic veins, of which there are several, carry out of 
the liver the blood which is carried in by the portal vein and 
hepatic artery, and empty it into the main channel of the venous 
circulation. (4) The hepatic duct begins in the lobules as a fine 
net-work of tubes, which unite to form larger and larger tubes, 
and finally terminates in one large one. This duct conveys the 
bile which is manufactured in the liver to the intestine. (5) The 
lymphatics are a part of a system of vessels which permeate the 
whole body, and will be described in another lesson. 
4. Bile. — This secretion of the liver is a clear, yellowish, or 
greenish yellow fluid, with a peculiar odor and bitter taste. It 
is composed mainly of water, but contains certain salts and a 
coloring matter which gives it a peculiar character. In some 
animals, the horse for example, the bile passes from the liver 
through the hepatic duct to the intestine, but in man it passes 
directly into the intestine only during digestion. At other 
times it “ backs up,” as it were, into a bag, called the gall cyst, 
or gall bladder. This bag lies on the under surface of the liver, 
and is attached to it by fibrous tissue, but is in no manner a part 
of it. The bile reaches the gall bladder through a tube called 
the cystic duct, which joins the hepatic duct to form the common 
bile duct (ductus communis choledoelms'), which enters the duo- 
denum just below the stomach. Thus, during digestion, the 
bile formed in the liver passes down the hepatic duct into the 
common bile duct, and from thence into the intestine; but 
when there is no digestible material in the intestine, the orifice 
of the common bile duct closes, and the bile backs up, and as it 
cannot return to the liver, because the hepatic duct is already 
full, it passes up the cystic duct into the gall bladder, and is 
there retained until needed in the intestine. The gall bladder, 
then, is a reservoir to hold the bile during the intervals of 
digestion. 
5. The Functions of the Liver. — It was formerly thought that 
the function of the liver was merely to secrete the bile. It is 70 
LESSONS IN PHYSIOLOGY. 
now known that it has other and important uses, one of which 
is the conversion of grape sugar to glycogen for the purpose of 
storage, and converting it back again into sugar as the latter is 
needed by the system. 
The following facts will explain the nature of this “ glycogenic 
function ” of the liver: (1) Grape sugar, or glucose, is one of 
the heat-producing elements of food, which is in constant demand 
in the system, and is found but sparingly in nature. (2) Starch 
is an abundant substance, but from its insoluble nature it cannot 
be absorbed into the blood. (3) The saliva and pancreatic juice 
are capable of converting starch and also cane sugar into 
glucose. (4) The demand for sugar in the system is constant, 
but digestion is periodical and not constant. (5) Glucose, being 
soluble, is readily absorbed. (6) Glucose, being soluble, cannot 
easily be stored in the system ready for constant use. (7) Gly- 
cogen resembles starch in not being soluble, and can be easily 
stored in the cells of the liver, and converted into sugar as 
needed by the system. 
The word glycogen means “ glucose generator,” so called from 
its readiness to change to sugar. It can be separated from the 
liver of a recently killed animal, and resembles starch someAvhat 
in appearance, hence is sometimes called animal starch. Starch 
is found mainly in the vegetable kingdom, and only sparingly in 
some of the lowest forms of animal life; and glycogen is found 
mainly in the animal kingdom, and only sparingly in the lower 
forms of vegetable life. 
6. The Pancreas. — This gland (called “ SAveetbread ” in 
animals) plays an important part in the digestive processes. 
It has been named by the Germans, “the abdominal salivary 
gland,” as its secretion, the pancreatic juice, resembles saliva in 
its action. The word pancreas means “ all flesh,” and was given 
to this gland before its real nature was known. It lies behind 
the stomach, is from six to eight inches long, one and a half 
inches broad, and from a half to one inch thick, weighing about 
three ounces. It is the shape of a dog’s tongue. In structure 
it resembles the salivary glands. The fluid it secretes passes 
into the duodenum through the pancreatic duct, THE LIVER, PANCREAS, AND SPLEEN. 
71 
The pancreatic fluid contains three peculiar ferments, one 
called amylopsin, which converts starch to sugar; another 
called trypsin, which converts albuminous foods into albu- 
minose; and a third called steapsin, which renders fats and oils 
capable of being absorbed. 
7. The Spleen. — This is a peculiar organ, located at the left 
extremity of the stomach. Its use is not clearly determined, 
although it is commonly described along with the organs of 
digestion. It is called a ductless, or blood, gland, because it 
secretes no special fluid, and has no duct. It is oblong and 
flattened in shape, and varies much in size, but is usually about 
five inches long, three to four inches broad, and about one and 
a half inches thick, and weighs about seven ounces. It is well 
supplied with blood-vessels and lymphatics. In malarial fevers 
it is frequently much enlarged, and the person is said to have an 
“ ague cake.” In some cases it has been known to attain the 
weight of twenty pounds. In appearance it resembles the liver, 
but is darker in color. 
As to structure, it consists of numerous blood-vessels, and a 
substance called spleen pulp, the whole traversed with fibrous 
bands. Since the spleen is slightly larger after a meal, it is 
supposed to act as a reservoir for the extra amount of blood 
manufactured in the digestive process. Broken red blood-cells 
are found in it, hence it has been said to be for the destruction 
of these blood-cells, or, as it is sometimes put, “ it is the grave 
of the red corpuscles.” It is supposed also to be one of the 
places where blood-corpuscles are produced. 
It has been removed many times from living animals without 
serious results, but in some cases several small spleens have 
developed in its place, and in others certain lymphatic glands 
have increased in size. The ancients supposed it was the seat of 
melancholy and anger, hence the expression, “he vents his 
spleen ” applied to one who expresses his angry feelings. 72 
LESSONS IN PHYSIOLOGY. 
LESSON 14. 
Intestinal Digestion and Absorption. 
1. Chyle. — As soon as the chyme passes into the small intes- 
tines from the stomach, it is subjected to the action of three 
different fluids, which have already been described, viz.: the 
bile, the pancreatic juice, and the intestinal juice. The result of 
the action of all these fluids upon the chyme is a milky white 
fluid, which has received the name of chyle, and the process of 
producing it is called chylification. The food, however, is not 
all converted into chyle, as much of it is indigestible, and the 
undigested portions remain mixed with the chyle, until the 
latter is absorbed. 
The white appearance of the chyle is due to the minute 
globules of fat which it contains. If a little oil be mixed with 
water in a bottle, the oil will rise to the top, and both liquids 
will appear transparent, or nearly so. Now if the bottle be 
vigorously shaken, the oil and water will mix, and the whole 
have a white appearance like milk. A close examination shows 
it to be composed of many very small globules of oil floating in 
the water. The globules will soon come to the top again if 
allowed to rest. If a gummy, or mucilaginous, substance be 
mixed with the oil and water, and the whole shaken, a per- 
manent mixture will be formed. It is then called an emulsion. 
The white color is caused by the many minute globules reflect- 
ing the light in all directions. 
The Chyle is an Emulsion. — The sugar and peptones in solu- 
tion correspond to the water and mucilage in the experiment, 
and the oil globules come from the fat or oily food that is eaten. 
The breaking up of the fat into minute globules is caused by the 
bile, pancreatic juice, and intestinal juice. Some authors state 
that these digestive fluids convert part of the fats into a kind of 
soap. 
2. Action of the Saliva. — As we learned in a previous lesson, 
the action of the saliva was mainly arrested in the stomach by INTESTINAL DIGESTION AND ABSORPTION. 
73 
the presence of the gastric juice, which is an acid fluid. When 
it arrives in the intestine, the bile and pancreatic juice, being 
alkaline, neutralize the gastric juice, and thus permit the saliva 
to resume its work of converting starch to sugar. 
3. Action of the Bile. — Certain constituents of the bile are 
believed to be waste material which the liver separates from the 
blood, and which, if allowed to remain, would poison the entire 
system. Certain other of its constituents are believed to be 
formed in the liver, and are doubtless concerned in the emulsify- 
ing of the fats to prepare them for absorption. 
4. The Action of the Pancreatic Juice. — This fluid, as we have 
learned, contains three distinct ferments, which act respectively 
upon the starch, the albuminoids, and upon the fats. It is, 
therefore, an assistant to the saliva, the gastric juice, and the 
bile. 
5. The Intestinal Juice is believed to exert an action upon the 
three classes of food, viz.: fats, albuminoids, and starch, and 
thus resembles the pancreatic juice in function. 
6. Absorption from the Intestine. — In the stomach, absorption 
is by veins alone. Fats cannot be absorbed in this manner, and 
in the intestine another method of absorption is provided. It is 
by the lacteals. These are minute, thread-like tubes, which take 
their beginning in the villi of the small intestine, and uniting 
into larger vessels, finally empty into one large tube called the 
thoracic duct. This is about the thickness of a goose quill, and 
from eighteen to twenty inches in length, extending along the 
front of the spinal column, and emptying its contents into the 
left subclavian vein, near the top of the sternum. 
Thus there are two methods of absorption in the intestines: 
by the veins and by the lacteals. The veins absorb water, holding 
in solution sugar and albuminose, and the lacteals absorb mainly 
emulsified fats, but also some of the albuminose and sugar. 
PRACTICAL ILLUSTRATIONS. 
Pour about a tablespoonful of clear water into a bottle. Add the same 
quantity of castor oil. Observe that the liquids do not mix, the oil remaining at 
the top, and that both liquids are nearly transparent. Now shake the bottle 74 
LESSONS IN PHYSIOLOGY. 
vigorously for a minute or two. Observe the change — a white fluid resembling 
milk. Close examination will show the minute globules of oil floating in the 
water. This is an emulsion. The oil and water will in time separate, the 
globules of oil coming to the top, and running together will become clear as 
before. To make a permanent emulsion some mucilaginous or gummy substance 
must be mixed with the oil and water, and agitated. 
Milk is a good example of a natural emulsion. The water holds in suspen- 
sion minute globules of oil (butter), surrounded by the casein, which is of an 
adhesive or gummy nature. 
LESSON 15. 
Uses and Kinds of Food. 
1. Assimilation. — What becomes of the absorbed material? 
It passes, as we have seen, either directly into the blood-vessels, 
or indirectly by means of the lacteals, and becomes a part of 
the blood. Thus the blood is constantly being renewed by 
additions from the digestive tract. But what is the final dis- 
position of the absorbed material ? It is used in building up the 
system, supplying the waste, and furnishing material for new 
growth. This process is called assimilation. Thus what existed 
yesterday as a part of an ox, an egg, or a head of cabbage, may 
to-day be a part of the tissues of your brain, muscles, or bone. 
2. Summary of Digestive Processes. — We may state the various 
processes which the food undergoes from the time it appears on 
the table until it becomes a part of our bodies, as follows: 
Prehension, or the seizing of the food ; mastication, or the grinding 
and crushing of the food; insalivation, or the mixing of the food 
with saliva; deglutition, or swallowing; chymification, or stom- 
ach preparation; chylification, or intestinal preparation; absorp- 
tion, or the passage of the prepared material from the alimentary 
canal into the blood-vessels; circulation, or the conveying of the 
material to the various tissues of the body; secretion, or the 
separation of certain materials from the blood, and combining 
them in the glands to form the various fluids of the body; 
assimilation, or the incorporation of the food material with the USES AND KINDS OF FOOD. 
75 
material of the body. These various processes may all be carried 
on at one and the same time. The processes of circulation and 
secretion will be discussed in succeeding chapters. The others 
have been explained. 
3. Classification of Foods. — I. As to composition, foods are 
divided into two great classes: (1) Carbonaceous, or non-nitrog- 
enons, including all those which do not contain nitrogen. These 
are again divided into two classes: (a) Carbo-hydrates, or those 
in which carbon predominates. These are mainly starch and 
sugar. Nearly every vegetable substance contains either one or 
both of these valuable food elements. (b) Hydro-carbons, or 
those in which hydrogen predominates. These are fats and oils, 
the former being solid, and the latter liquid, at the temperature 
of the body. A great many vegetable foods contain oils; the 
fats are derived mainly from the animal kingdom. (2) Nitrog- 
enous, or albuminous, including all those which contain nitrogen, 
as well as carbon, oxygen, and hydrogen. They are: albumen, 
found nearly pure in the white, also in the yolk, of the egg; 
fibrin and gelatine, the principal parts of the flesh of animals; 
legumen, in beans, peas, and some other vegetables; gluten, 
found in all grains, especially in the outer part of the wheat 
grain ; and casein, in milk. 
II. As to nutrition, foods are divided into two great classes. 
(1) Calorifacient, or heat-making, and (2) histogenetic, or tissue- 
making. The heat-making foods are mainly the carbonaceous, 
and the tissue-making mainly the nitrogenous. It has been 
demonstrated that man cannot live on one of these classes of 
food to the entire exclusion of the other. All food articles, 
however, contain both of these elements, but in varying propor- 
tions. A few articles only contain them in the proper propor- 
tion, and life may be sustained by their exclusive use. Thus 
milk contains butter (carbonaceous) and casein (nitrogenous); 
eggs contain oil and albumen; wheat, rice, and other grains 
contain starch and gluten ; beans contain starch and legumen ; 
and any one of these articles could be used to the exclusion of 
all other articles of food. 
4. Animal Heat. — The temperature of the interior of the 76 
LESSONS IN PHYSIOLOGY. 
human body in health remains nearly the same under all cir- 
cumstances. Thus a man may remain for a few minutes without 
danger in an oven heated to 350° Fahrenheit, yet the tempera- 
ture of his body will be but slightly affected. On the other 
hand, a man may endure a temperature of 40° below zero, Fah- 
renheit, without greatly lowering his body temperature. In the 
first instance, the evaporation of the perspiration will keep the 
temperature from rising, and in the second instance, the heat 
that is abstracted by the atmosphere is resupplied by combustion 
of fuel in the shape of carbonaceous food in the body. 
Therefore in winter, and in cold climates, men must have food 
to keep up the body temperature, as well as to supply the waste 
and produce growth of new tissues. The heat-making food is 
needed to some extent in all climates, and at all seasons of the 
year, as the temperature of the body is in most cases a little 
higher than that of the surrounding atmosphere. 
In cases of starvation, the fat of the body is absorbed and 
carried into the general circulation, to be burned up as fuel to 
keep up the animal heat. When it is exhausted, the muscles 
and other soft parts are drawn upon, until finally death follows 
from lack of fuel to keep up the temperature essential to life. 
A starving animal becomes lean from this consumption of 
reserve material. Clothing answers to a certain degree the 
place of food by keeping in the animal heat. 
5. Recapitulation. — Thus we have learned that there are two 
great classes of foods, those which contain nitrogen, and those 
which do not; and that the first of these is for building and 
keeping the body in repair, and the second for keeping it warm. 
Also, that nature provides in reserve a storehouse of fuel in 
the shape of the fat of the body for use in emergencies. How 
the fuel is consumed will be discussed under the Respiratory 
System, and the process of absorption, whereby the reserve store 
of material is carried into the blood to be consumed or used 
again, will be described under the Secretory System. HYGIENE OF DIGESTION. 
77 
LESSON 16. 
Hygiene of Digestion. 
1. There is a tendency among certain writers on Hygiene 
to overrate the relative importance of this part of the subject. 
If the laws of health in regard to fresh air, exercise, sleep, 
cleanliness, temperature, and use of stimulants be strictly 
observed, our appetite will in a great measure be a suffi- 
cient guide in the matter of diet. There are, however, cer- 
tain principles which ought to be kept in mind in choosing our 
food and in the manner of preparing and eating it. 
2. Quantity of Food. — It is impossible to lay down rules 
regarding the amount of food necessary to maintain the body 
in the best possible condition. The proper amount depends 
upon a variety of conditions, some of which are here given: 
(1) During the growing period, when the system needs food 
to produce increase in size as well as to supply waste and 
create warmth, it is evident that more food is needed in pro- 
portion to the weight of the body than at other times. (2) More 
food is required in cold climates and in winter than in sum- 
mer unless particular care is taken to select foods rich in carbo- 
naceous material. (3) Persons whose occupations demand much 
bodily exertion need more food, other things being equal, than 
those whose occupations are sedentary. A lady who had kept a 
boarding-house for railroad laborers and afterwards one for col- 
lege students declared that she made as much money boarding 
the students at half the price paid by the laborers, for they ate 
only half as much. (4) Some persons eat less than others under 
the same circumstances of age, temperature, occupation, etc., 
and we can account for it only by the supposition that they have 
either formed a habit of eating less, or that there is a difference 
in temperament whereby the waste and repair in the cells goes 
on more slowly. (5) Persons in a depressed state of mind, or 
engaged in work calling for exercise of the emotions, should 
eat less, as the digestive organs under such circumstances do 78 
LESSONS IN PHYSIOLOGY. 
not act so readily. (6) An increase in the amount of pure 
air inhaled seems to increase the appetite and the need for food 
in the body, as there is more rapid consumption of fuel caused 
by the increased amount of oxygen taken into the system. 
We have all observed the increased appetite of those who are 
hunting and fishing or rambling in the woods and fields. 
To sum up, the appetite if not perverted is a good guide as 
to the proper quantity of food. A healthy appetite must not 
be confounded with mere pleasure of the taste of food or an 
unnatural craving for certain articles. Plain, substantial food 
will not pervert the appetite, and can do no harm to a healthful 
person if eaten until there is actually no desire for more. 
3. Quality of Food. — Man is an omnivorous creature. Tak- 
ing the world over, all imaginable things that are digestible, 
and even some which are not digestible, are eaten by human 
beings. In Eastern Asia, Island of Java, in Northern Europe, 
and along the Amazon River, the natives eat clay, which affords 
no nourishment, but is said to allay hunger; probably by di- 
luting the real food, causing it to spread over a greater surface 
and be more readily absorbed. There is no bird or beast, no 
insect or reptile, that the Bushmen of Africa will not eat. 
What is eagerly sought after and relished by some nations is 
disgusting to others. Hunger has probably driven men to eat 
certain articles in the first place, and habit, which finally 
became inherited, kept it up in the tribe or nation. 
Neither mere taste nor habit should be the sole guide in 
choosing food. Two important facts should always be borne in 
mind: (1) The food should be wholesome; that is, free from 
any poisonous elements. Food is unwholesome which is taken 
from vegetables or animals not in a healthy condition. Germs 
of disease are in this way introduced into the system. Food is 
frequently unwholesome when it has commenced to decay. 
In the decay of many animal and vegetable substances poison- 
ous compounds are produced. Stale vegetables and “high” 
meats should be avoided. (2) The food should contain a due 
proportion of heat-making and tissue-making elements. Since 
the former is more in demand in the winter, foods containing HYGIENE OF DIGESTION. 
79 
starch, sugar, and fats or oils should predominate. During 
the hot season, lean meats, soups without fat, and watery vege- 
tables and acid fruits are not only more agreeable, but more in 
accordance with the needs of the system. 
Food should not be too highly concentrated, nor too easy 
of digestion, nor yet too bulky and difficult of digestion; for 
in the first case, the stomach will have but little exercise, 
and in the second case it may be overworked and become un- 
duly enlarged, and either extreme will tend to produce dys- 
pepsia. 
There has been much controversy as to whether a purely 
vegetable or a mixed diet of animal and vegetable food is pref- 
erable. Man may live and be healthy on purely vegetable food, 
as has been demonstrated by the experience of thousands, yet 
this does not prove that a mixed diet is unwholesome. The 
majority of scientific men who have expressed an opinion are 
in favor of a mixed diet. Dr. Carpenter, an eminent authority 
in physiology, is of the opinion that a well-selected vegetable 
diet conduces to the highest physical development, while a 
moderate proportion of animal food seems to favor the highest 
mental development. 
4. Cooking. — The object in cooking food with most people 
is to render it more palatable. The flavor seems to be devel- 
oped or changed by the process of heating. But with many 
kinds of foods cooking makes them also more easily digested, 
by softening or rendering them more capable of being absorbed. 
Cooking also destroys certain parasites which may infest meats. 
Pork, as is well known, sometimes contains trichina, a minute 
parasitic animal which multiplies and develops rapidly in the 
human stomach, and then finds its way to the muscles to enter 
a dormant state or become encysted, the irritation thus pro- 
duced causing a painful and frequently fatal disease. Beef 
and mutton and pork may contain the germs of tapeworms, 
which will develop in the human alimentary canal and cause an 
annoying, if not serious, disease. Heating meats to the boil- 
ing point of water destroys these animals, and renders the 
meats containing them harmless. 80 
LESSONS IN PHYSIOLOGY. 
There are many methods of cooking meats and vegetables, 
but perhaps the only one that is objectionable is frying, as 
it is ordinarily practiced. If, however, the fat be made very 
hot before the meat is put in, the surface is seared and made 
crisp, and the fat does not penetrate the meat. While the fat 
is not injurious in itself, if permitted to penetrate the meat, 
it prevents the action of the gastric juice on the albuminous 
matter, and digestion is thus retarded. Fried meats should 
be eaten at once, as the fat will penetrate the fibers if the meat 
be allowed to remain long after being cooked. Foods eaten 
while warm are usually more easily digested, as the tempera- 
ture of the stomach is not lowered. 
5. Variety in Diet. — Our appetites seem to demand a variety 
of food. One soon tires of the same article prepared precisely 
in the same manner every day. To eat one roast quail each day 
for thirty days in succession was until recently considered an 
impossible feat, but stimulated by heavy wagers several have 
succeeded by great effort in accomplishing it. There are some 
articles, however, which we never seem to tire of, when a few 
other articles are eaten with them. Bread with milk or eggs 
may be relished for a very long time. Either of these foods con- 
tain all the elements necessary to sustain life. We occasion- 
ally find a person who has lived from childhood to old age 
almost exclusively on a diet of bread and milk. Many Eastern 
people, as the Hindoos and Chinese, live almost exclusively 
upon rice. It is not best to have a great variety at each meal, 
as then we are tempted by the taste of the viands to eat more 
than the appetite really demands. 
6. Regularity in Eating. — In view of what was said in a pre- 
vious lesson concerning the tendency of the digestive organs to 
act periodically, you will infer that meals should be at regu - 
lar hours. If we become accustomed to having meals regularly, 
shortly before the time comes we feel hungry. This sensation 
will pass away if the meal is delayed, and probably Avill not 
return again until the time of the next regular meal. Now, if 
we eat after the hunger sensation has left us, our appetites 
cannot be a true guide to the proper amount of food. The HYGIENE OF DIGESTION. 
81 
digestive system then becomes like a musical instrument out 
of tune. 
7. Frequency of Meals. — The custom of eating three times 
in twenty-four hours is perhaps the best one, yet with seden- 
tary persons a habit of eating but twice in twenty-four hours 
may be formed with excellent results. Some eat four and even 
five times a day without apparent ill effects. Young children 
should eat oftener than adults, but a habit of eating between 
meals at irregular hours is a bad one. 
8. Manner of Eating. — Plenty of time should be taken for 
meals. Eat slowly, that you may have time to masticate 
thoroughly, and that the saliva and gastric juice may have 
time for secretion. The glands require time to respond to 
the nervous stimulus excited by the smell and taste of the 
food and its presence in the mouth and stomach. We are less 
liable to eat too much when we eat slowly. Lively conversa- 
tion at meals favors digestion, as a cheerful state of mind 
favors the action of the glands. 
9. Temperature of Food. — It would appear reasonable that 
warm foods would be more easily digested, since they do not 
change the temperature of the stomach, yet some persons seem 
to suffer no ill effects whatever from the use of ice water or 
iced tea at meals, and can eat with impunity quantities of ice 
cream. Others cannot tolerate cold drinks and foods. As a 
rule it behooves all to be cautious concerning ice cold foods 
and drinks, as many a case of dyspepsia may be traced to their 
use. 
10. The Use of Condiments. — Salt seems to be a necessary addi- 
tion to food, yet there are some who claim that all food contains 
a sufficient amount naturally and that none should be added. 
This is an extreme view, and is doubtless an erroneous one. 
There are, it is said by travellers, tribes in Africa who use no 
salt with their food; but they also state that the water of that 
country contains salt, and that Europeans while travelling in 
that country do not feel the want of it. Salt gives relish to 
many kinds of food which otherwise are almost tasteless. It 
seems to develop or bring out their flavor. An excessive 82 
LESSONS IN PHYSIOLOGY. 
use of salt is no doubt injurious, as it creates thirst, the 
gratification of which may be the cause of overworking the 
absorbent vessels and excretory glands in getting rid of the 
superfluous water. 
The spices, as pepper, cloves, nutmeg, cinnamon, etc., are 
relished by most persons, and a moderate use of them seems 
to do no harm. An excessive use of them blunts the sense of 
taste. Habit has much to do with their toleration by the sys- 
tem. Children generally dislike pepper, while adults generally 
like it. The Mexicans, as is well known, are accustomed to 
eating red peppers as we would eat cabbage or potatoes. 
11. Water. — It is an almost universal custom to take either 
water or some fluid consisting mainly of water along with the 
food. Some have contended that this retards digestion, but 
unless excessive quantities be used this cannot be true, as the 
water dissolves certain portions of the food, and is rapidly ab- 
sorbed from the stomach, carrying along with it products of 
digestion. Excessive quantities overtax- the absorbent vessels 
and dilute the fluids of digestion to an undue degree. The 
amount to be taken should vary with the nature of the food. 
Some kinds of food, being largely composed of water, require 
less, and others, being dry, require more. The natural desire 
or sensation of thirst is usually a good guide. Highly seasoned 
food creates an unusual desire for water, and for this reason 
should be sparingly eaten. 
The use of ivarm or hot water at meals is highly recommended. 
The beneficial effects of tea, coffee, and chocolate are fre- 
quently due to the fact of their being warm drinks. Persons 
with weak digestive powers are doubtless benefited by drink- 
ing warm fluids at meals. 
Water should be wholesome; that is, free from injurious 
ingredients. We cannot say water should he pure, for pure 
water does not exist in nature. Water so readily dissolves 
solids and absorbs gases that all water contains more or less 
foreign substances. Perfectly pure water is not agreeable to 
the taste. A certain amount of mineral salts and absorbed 
gases give water its sparkle and life and make it palatable. HYGIENE OF DIGESTION. 
83 
But decaying organic matter, and an excess of mineral salts, 
and the presence of germs of disease in water make it unwhole- 
some. The selections of wholesome waters will be discussed 
in another chapter. 
12. Effects of Tea, Coffee, and Chocolate on Digestion.—■ These 
drinks have little, if any, direct effect on the digestive organs. 
They doubtless aid digestion from the fact that they are taken 
as warm drinks, thus keeping up the natural temperature of 
the stomach. Indirectly they affect digestion by retarding waste 
in the system. In this sense they may he regarded as nega- 
tive foods. It has been observed that persons who use these 
drinks habitually require less food. When used in excess they 
injuriously affect the nervous system in some persons, and 
more especially in the young, and thus indirectly affect the 
digestive organs, which, like all other organs, are controlled 
by the nerves. 
13. Effects of Alcohol on the Digestive Organs.— Alcohol is a food 
only in the negative sense that it retards waste in the system. It 
affords no nourishment, and while small quantities thoroughly 
diluted may increase the appetite, and for a short time stimulate 
the digestive powers of the stomach, any continued use of it, 
even in a diluted form, will result in serious injury to all of 
the digestive organs. Its first effect is to increase the flow 
of blood to the capillaries. This causes engorgement of the 
blood-vessels of the stomach. They become distended and 
weakened. The man who takes alcoholic stimulants to improve 
his appetite and digestion soon gets into a condition where he 
will have no appetite, and digestion will be improperly per- 
formed unless he gets his accustomed stimulant. But every 
time it requires a little more to produce the effect, until a habit 
of taking considerable quantities is formed, and this increased 
quantity tends to pervert and destroy the functions of the 
parts; for all powerful stimulation or activity is followed by 
a corresponding depression or inactivity. 
The liver is affected by a habitual use of alcoholic drinks. 
It becomes hardened, and sometimes covered with little lumps, 
producing what is known among physicians as “hobnail liver.” 84 
LESSONS IN PHYSIOLOGY. 
Sometimes there is “fatty degeneration,” the liver substance 
partly disappearing and fat being deposited throughout its 
mass. 
It is no longer a question of opinion among physicians as to 
whether an excessive use of alcoholic liquors injures the 
digestive organs. It is an established fact. The records of 
every hospital in the country will show hundreds of proofs 
of the injury done by alcohol upon these organs. As to the 
question whether the milder alcoholic drinks, as beer, ale, 
porter, and the weaker wines and hard cider, when used in 
moderation, have an evil effect, there are many different opin- 
ions among physicians; but this much is true, and almost all 
admit it, that a moderate use of the milder forms of drink 
inevitably leads to deeper indulgence, and excess is thus soon 
reached, and the final result is the same. Physicians almost 
universally agree as to the evil effects upon the young. During 
the period of growth all stimulants and narcotics have the effect, 
in a greater or less degree, of retarding natural development. 
14. Tobacco and Digestion. — In many cases the smoking or 
chewing of tobacco leads to dyspepsia of the worst form. In 
chewing tobacco the salivary glands are excited when no food 
is present to use the saliva. This valuable fluid is therefore 
wasted, and the constant stimulation of the glands tends to 
weaken them, and the quality of the saliva is deteriorated and 
less effective in converting starch to sugar. Through the ner- 
vous system the smoking of tobacco frequently produces inju- 
rious effects upon the heart and circulation of the blood, and 
thus indirectly affects digestion. 
It is a common belief that the use of tobacco leads to the use 
of alcoholic liquors; but there is no good ground for such a 
belief. Some physicians are of the opinion that it is in a cer- 
tain sense a substitute for ardent spirits, and in many cases 
prevents men from forming habits of drinking. Physicians 
and men of science are almost unanimous in the belief that 
tobacco is very injurious during the growing period of life, 
and we all know that if the habit is not formed in youth 
there is little danger of its being formed late in life. HYGIENE OF DIGESTION. 
85 
15. Care of the Teeth. — As formerly stated, there are cases 
in which the teeth decay early in spite of all precautions, and 
again other cases in which without care they remain sound 
until old age; yet experience shows that it pays to take care 
of the teeth, as frequently their early decay is directly tracea- 
ble to neglect. Particles of food left in the mouth ferment 
and form acids which destroy the teeth. The enamel may 
be cracked and broken by biting threads, cracking nuts, and 
in similar ways. Very cold and very hot foods and drinks 
tend to crack the enamel. When once the enamel is broken 
and foreign substances come in contact with the dentine the 
decay is usually rapid. The moral is: Keep the teeth clean; 
avoid extremely hot and extremely cold foods and drinks, and 
use the teeth for masticating food only. 
Use a soft tooth brush and a little mild soap and water after 
each meal. Occasionally a little powdered charcoal used on 
the brush will keep the teeth white, but if used frequently it 
will wear the enamel. Never use a metal toothpick. 
EXERCISES FOR REVIEW. 
1. Name the classes of teeth as to duration. As to form and use. 
2. What is the hardest substance in the animal kingdom? What is its 
use ? 
3. What is the use of the salivary glands ? What is the “ abdominal salivary 
gland”? 
4. Name the openings of the pharynx. Of the stomach. 
5. The uses of saliva. What is ptyalin ? What is its action ? 
6. What propels the food from the mouth to the stomach ? Could a man 
swallow while standing on his head ? 
7. What part of the digestive process takes place in the mouth? In the 
stomach ? In the intestines ? 
8. What is the gastric juice ? Why does the stomach not digest itself ? 
9. Name some of the circumstances affecting stomach digestion. 
10. What vessels carry material into the liver ? What vessels carry material 
out of the liver ? 
11. What are the functions of the liver ? What is glycogen ? 
12. Name the ferments of the pancreatic juice. State the uses of each. 
13. How does the bile get into the gall bladder ? How does it get out ? What 
is the use of the gall bladder ? 
14. Why is chyle white ? What is an emulsion ? 86 
LESSONS IN PHYSIOLOGY. 
15. What materials are absorbed from the stomach ? What are the agents 
of absorption in the stomach ? What is absorbed from the intestine that is not 
absorbed in the stomach ? 
16. What are villi ? Their use ? 
17. Name the kinds of food as to composition. As to nutritive value. 
18. Name all the processes of digestion. 
19. How does alcohol affect the mucous coat of the stomach ? In what 
manner may tobacco be injurious to the digestive organs ? 
20. What part does water play in the digestive processes ? 
21. Is alcohol a food? 
22. Give directions for caring for the teeth. 
23. Write an essay on “The Liver,” using the following outline of points: 
location, size, weight, color, covering, ligaments, vessels, lobes, minute structure, 
secretion, glycogenic function, effects of alcohol upon. CHAPTER II. 
HOW THE NOURISHMENT IS CARRIED THROUGH THE BODY, OR 
THE CIRCULATORY SYSTEM. 
LE1SSON 17. 
The Heart. 
1. Definition and Location. — The heart is the main organ of 
circulation in all higher animals. It is a muscular pump which 
receives the blood from certain pipes (veins), and by its contrac- 
tions forces it through other pipes (arteries) to every part of the 
body. It lies between the lungs, its greater portion being on 
the left of the middle line of the thorax. Its broadest part, or 
base, points upward, backward, and to the right; its smaller end, 
or apex, points downward, forward, and toward the left. A line 
drawn at right angles to the long axis of the body and touching 
the upper border of the cartilage of the third rib will mark its 
upper portion. Its apex lies behind the space between the car- 
tilages of the fifth and sixth ribs, a little to the left of the ster- 
num, where it can be felt beating. 
2. Size and Shape. — The human heart is about the size of the 
fist of its possessor, or usually in a grown person, five inches in 
length, inches in breadth, and 2£ inches in thickness, and 
weighs from eight to twelve ounces. The heart of a full-grown 
sheep or hog is about the same size and shape as the human 
heart. Its shape is that of a cone, somewhat flattened. 
3. Cavities. — The heart is divided by a partition running 
lengthwise into two distinct portions, called the right and left 
sides. It is really a double organ, one side pumping venous 
blood, the other side pumping arterial blood. Each side has 
two cavities, the upper called auricles, into which the blood is 88 
LESSONS IN PHYSIOLOGY. 
received, the lower called ventricles, from which the blood is 
discharged. 
4. The Eight Auricle is a little larger than the left, with thinner 
walls and shows when cut open the following parts: — 
1. Openings. 
(a) Mouth of the superior vena cava, the large vein which 
brings the blood from the upper part of the body. 
(5) Mouth of the inferior vena cava, the large vein which 
brings the blood from the lower part of the body. 
(c) The mouth of the coronary vein, which returns the blood 
from the substance of the heart itself. 
(c7) The mouths of many little veins, which also return blood 
from the walls of the heart. 
(e) The opening into the right ventricle. 
2. Valves. 
(a) The Eustachian valve, which is scarcely perceptible in the 
adult, but previous to birth, when the circulation takes a differ- 
ent course, it is a fold of the lining of the heart and serves to 
direct the blood from the left auricle through an opening in the 
right auricle. This opening closes at, or shortly after, birth. 
(J) The coronary valve is a fold of the lining which prevents 
the blood from going back into the coronary vein. 
5. The Eight Ventricle is the same size as the left, but the walls 
are much thinner. When laid open it shows : — 
1. Openings. 
(<*) From the auricle. 
(b) From the pulmonary artery which carries the blood to 
the lungs. 
2. Valves. 
(a) The Tricuspid (three-pointed). It consists of three tri- 
angular flaps of tough membrane hanging from the opening and 
connected by fibrous cords to fleshy columns in the walls of the 
ventricle. When the heart contracts to throw the blood out, THE HEART. 
89 
these flaps are pulled together and close the opening so that the 
blood cannot pass back into the auricle. 
(b) Semilunar (half-moon) valves. These are like little pockets 
in the walls of the mouth of the pulmonary artery. The pock- 
ets open towards the artery, and when the ventricle contracts 
and forces the blood into the pulmonary artery, they offer no 
resistance, but the blood is prevented from returning, by the 
pockets filling up and bulging out so as to close the opening. 
6. The Left Auricle is more simple than the right, showing 
only (u) the openings of the four pulmonary veins which return 
the blood from the lungs, and (b) the opening into the ventricle 
below. 
7. The Left Ventricle is similar to the right, showing: — 
1. Openings. 
(a) From the left auricle. 
(b) From the aorta, or great arterial trunk, which sends blood 
to all parts of the body. 
2. Valves. 
(a) The Mitral (from the resemblance to a bishop’s cap, or 
miter'); similar in construction and action to the tricuspid 
valves, except that there are but two instead of three triangular 
flaps of membrane. It prevents the blood from returning to the 
auricle. 
(b) Semilunar valves in the mouth of the aorta. They are ex- 
actly similar in structure and use to the semilunar valves in the 
pulmonary artery. 
8. The Pericardium. — The heart is well protected from injury, 
yet has perfect freedom for the necessary motion. It hangs by 
the large blood-vessels which are connected with it, and is sur- 
rounded by a fibrous membrane, the pericardium (around the 
heart), which encloses it like a bag. This membrane blends 
with the coats of the large blood-vessels, and is attached at one 
point to the diaphragm, so that it helps to hold the heart in 
position. It is lined with a serous membrane which turns and 
covers the heart also. This serous membrane secretes a fluid 90 
LESSONS IN PHYSIOLOGY. 
which keeps the surfaces moist, so that the heart may move 
without friction. When the membrane is diseased, the fluid 
sometimes is greatly increased in quantity, producing what is 
known as “ dropsy of the heart.” 
9. Structure. — The cavities of the heart are lined with a se- 
rous membrane which is continuous with the inner coat of the 
blood-vessels. It is sometimes called the endocardium (within 
the heart). The heart itself consists mainly of muscular fibers 
intricately interlaced and attached to fibrous rings surrounding 
the openings between the auricles and ventricles and around 
the mouths of the blood-vessels. The contractions of these 
muscular fibers lessens the cavities and forces the blood on- 
ward. 
10. The Motions of the Heart consist of alternate contraction 
(systole) and relaxation (diastole) of its muscular walls. The 
two auricles contract at the same instant, sending the blood into 
the ventricles, which are at that instant relaxed. Then the two 
ventricles contract, forcing the blood into the arteries, and at this 
instant the auricles are relaxed. These contractions and relaxa- 
tions follow each other so rapidly that the whole appears like a 
wave motion passing from the base to the apex of the heart. 
When the ventricles contract, the heart is tilted so that the apex 
strikes the wall of the chest. The heart pulsates, or contracts 
and relaxes, on an average, in the adult, seventy times per min- 
ute. In infancy motion is more rapid, becoming less in youth 
and manhood up to middle and old age. At birth it is from 
130 to 140 per minute. The pulsations are more frequent in 
women than in men, more frequent during exercise and just 
after eating, and less frequent during sleep. The rate varies 
much in diseased conditions. It has been known to be as low 
as twenty and as high as 160 per minute. 
11. The Sounds of the Heart. — During the pulsation two dis- 
tinct sounds are heard. The first is dull, and caused by the con- 
traction of the ventricles, the opening of the semilunar valves, 
and the rush of blood into the aorta. The second sound is sharp, 
and caused by the shutting of the semilunar valves. Between 
the second and first sounds there is an interval of silence, THE HEART. 
91 
These sounds are valuable aids to physicians in discovering' 
disease of the heart; for when there is a change in the natural 
condition of the heart, the sounds vary in character. 
12. The Work of the Heart. — Dr. B. W. Richardson has found 
that the amount of work done by the heart of a healthy adult 
man is equal to raising 10,400 pounds to the height of one foot 
in one hour; or, from another point of view, it is equal to send- 
ing the blood 207 yards in a minute, or seven miles in an hour, or 
5,150,880 miles in a lifetime of eighty-four years. The number 
of pulsations in that time would aggregate 2,869,776,000. 
PRACTICAL ILLUSTRATIONS. 
1. Get from the butcher the heart of a sheep or pig. If possible, get it with 
the lungs attached ; and tell the man who cuts it out of the animal to be careful 
not to destroy the bag containing the heart. Place the whole in a vessel of cold 
water, and let it stand for an hour to remove the blood. Remove carefully the 
fat from around the blood-vessels at the base, but be careful to preserve the 
pericardium. 
2. Cut a slit in the pericardium just large enough to push the heart out 
through it. Observe the smooth, shining surface of the heart and of the inside 
of the pericardial sac. 
3. Cut a small piece from the apex of the heart. Observe the solid, muscular 
mass at the cut surface. Cut several thin slices until you come to the cavities 
of the ventricles. Note the difference in the thickness of the walls of the right 
and left sides. By carefully cutting away the lower end you can look into the 
ventricles and see all the cords and membranes of the mitral and tricuspid 
valves. Observe the muscular columns on the walls of the ventricles. 
4. If the heart has not been separated from the lungs, only a part of the 
blood-vessels attached to the heart will have been cut off. Find the cut end of 
the aorta and push a piece of rubber tubing into it. If this be not at hand, you 
can use a flexible twig of willow, or something similar. In the same manner 
find the cut ends of the superior vena cava and the inferior vena cava, and 
trace them into the heart. If the pulmonary artery and veins have not been 
severed, you may find them, and, by cutting slits in them, insert twigs or tubes. 
You may have some difficulty in finding veins, as they are soft tubes, and col- 
lapse when empty, but arteries stand out like rubber pipes and are more easily 
found. 
5. Now push your finger up through one of the ventricles and try to reach 
the cavity of the auricle. Then cut down carefully from above against your 
finger. Enlarge the opening until you can observe the valves from the auricle 
side. Notice the points where the sticks which you had thrust into the blood- 
vessels have come out. 
6. Show the semilunar valves by slitting down the aorta and pulmonary artery. 92 
LESSONS IN PHYSIOLOGY. 
7. By the aid of these directions and the description of the heart given in the 
lesson you will have no difficulty in making this dissection, and it will amply 
pay for the time and trouble. No clear idea can be had from descriptions alone, 
no matter how complete they may be. 
LESSON 18. 
The Blood-Vessels. 
1. The blood-vessels are a system of elastic pipes which con- 
vey the blood or nourishing material to all parts of the body. 
They are of three kinds,— arteries, veins, and capillaries. The 
arteries are those vessels which 
carry blood from the ventricles 
of the heart and distribute it 
to all parts of the body. The 
veins are the vessels which 
return the blood from all parts 
of the body to the auricles of 
the heart. The capillaries are 
the fine tubes which connect 
the veins with the arteries 
throughout the tissues of the 
body. 
2. The Aorta. — This is the 
main trunk of the arterial sys- 
tem, which divides and sub- 
divides until all parts of the 
body are reached with branches. 
It is about one inch in diam- 
eter, and commences at the up- 
per part of the left ventricle, 
ascends behind the sternum, 
then curves over from left to 
right, and backward to the 
third dorsal vertebra, then descends along the left side of the 
spinal column to the lower border of the fourth dorsal verte- 
Fig. 10. — View of the Heart with 
the Great Vessels of the Neck. 
5, Arch of aorta; 7, Sup. vena cava; 10, 
innominate artery ; 11, Right inno- 
minate vein ; 12, Left innominate 
vein; 14, Subclavian veins; 15, Right 
common carotid artery; 16, Jugular 
veins. THE BLOOD-VESSELS. 
93 
bra, where it takes the name of the thoracic aorta. The part 
above this point is called the arch. The thoracic aorta passes 
through an opening in the diaphragm in front of the last dorsal 
vertebra, and then takes the name of the abdominal aorta, which 
terminates on the left side of the fourth lumbar vertebra, where 
it divides to form the right and left common iliac arteries. 
3. The Principal Arteries. — The aorta gives off from its arch, 
generally, five branches: (1) 
the right and left coronary, 
which supply the heart-sub- 
stance with blood ; (2) the 
innominate artery, which as- 
cends, and opposite the top 
of the sternum divides into 
the right carotid and right sub- 
clavian arteries; (3) the left 
carotid; and (4) the left sub- 
clavian. The two carotid ar- 
teries each divide opposite the 
larynx into the internal and 
external carotids. The former 
enters the cranium, and 
branches to different parts of 
the brain. The latter sup- 
plies the face and scalp by 
numerous branches. The sub- 
clavian arteries supply the 
arms and part of the chest. One branch, the vertebral, 
passes along the spinal column through openings in the trans- 
verse processes of the cervical vertebrae, and entering the skull, 
the two join to form the basilar artery, which again divides and 
each branch sends branches to the carotid arteries, which are 
also joined by an anastomosing branch. Thus a complete circle 
(called the Circle of Willis') is formed at the base of the brain; 
and if the blood is from any cause checked in one set of vessels, 
the other set ensures a supply. 
The subclavian arteries take the name of axillary under the 
Fig. 11. — Side View of the Super- 
ficial Arteries and Veins of the 
Neck. 94 
LESSONS IN PHYSIOLOGY. 
arm, and brachial in the upper arm, dividing at the elbow into 
the ulnar and radial arteries. Branches from the ulnar and 
radial join in the palm of the hand and form the palmar arch, 
from which small arteries are given off to the fingers. 
Returning to the aorta, the principal branches below the arch, 
are: (1) The coeliac axis, a short, thick artery which divides into 
the gastric, supplying the stomach, the hepatic, supplying the 
liver, and the splenic, entering the spleen; (2) the superior 
mesenteric; and (3) the inferior mesenteric, supplying the intes- 
tines. 
The terminal branches of the aorta are the right and left com- 
mon iliacs, which, are about two inches in length, and divide to 
form the internal and external iliacs. The former supplies the 
organs within the pelvis, and sends branches to its walls. The 
latter extends to the thigh, taking the name of femoral after it 
leaves the trunk. As it passes behind the knee it is called 
the popliteal artery. Below the knee it divides into the anterior 
and posterior tibial arteries. An arch is formed by their union 
in the foot called the plantar arch, from which branches pass to 
the toes. 
4. Structure of the Arteries. — These tubes are composed of 
three distinct coats: (1) The outer, of connective tissue, with 
elastic fibers; (2) the middle, of elastic and muscular fibers, the 
latter being more numerous in the smaller arteries; (3) the 
inner, a serous membrane resembling that which lines all cavi- 
ties of the body not accessible to air. If a string be tied tightly 
around an artery the middle and* inner coats will be severed, 
but the outer will remain uninjured. The outer coat gives 
strength, the middle elasticity and contractility, and the inner 
coat affords a smooth surface for the flow of the blood. 
When an artery divides, each branch is smaller than the 
main artery, but the combined area of the two is greater than 
the area of the main one. Thus, if all the arteries could be 
fused into one, we would have a funnel-shaped tube, with the 
smaller end at the heart. The arteries in many places send 
branches which join each other. This is called anastomosing. 
This is of great advantage to the surgeon, for should he be THE BLOOD-VESSELS. 
95 
obliged to tie a main artery, the blood can flow around through 
these anastomosing branches and re-establish the circulation. 
5. The Principal Veins. — These vessels are more numerous- 
than the arteries. They are divided into three sets: (1) The 
Fig. 12.— A Front View of the Relative Positions of the Veins and 
Arteries of the Face and Neck. 
On the right side the superficial vessels are seen, and the deep-seated ones on the left. 
superficial, found near the surface of the body, generally small 
and very numerous; (2) the deep, found accompanying the 
arteries, usually enclosed in the same sheath with them, and 96 
LESSONS IN PHYSIOLOGY. 
generally two to each artery; (3) the sinuses, venous channels 
found only in the interior of the cranium, and formed by a sep- 
aration of the dura mater, or membrane covering the brain. 
Fig. 13. — Veins of Extremities. 
The great vein which receives the blood from the upper part 
of the body is the superior vena cava, and that which receives 
the blood from the lower part of the body is called the inferior 
vena cava. The principal branches of these take the same names THE BLOOD-VESSELS. 
97 
as the arteries which they accompany. The sinuses of the dura 
mater have special names. The word sinus used in this connec- 
tion must not be confused with the word which describes air- 
cavities in the bones of the skull, as the frontal sinus. The 
superficial veins may be seen in many places, as on the back of 
the hand, standing out like cords beneath the skin. They join 
the deep viens, and the larger ones have special names. 
6. The Structure of Veins. — Like arteries they have three coats, 
which differ mainly in the comparative weakness of the middle 
coat and the scarcity of muscular and elastic fibers. For this 
reason a vein collapses when empty, while an artery remains an 
open tube. Most of the veins are provided with valves. These 
are simply folds of the inner and middle coats, which permit 
the blood to pass freely towards the heart, but prevent its flow 
in the opposite directions. The veins freely anastomose with 
each other, in the same manner as the arteries. 
7. The Capillaries. — The blood-vessels which connect the 
arteries and veins were called capillaries, from the Latin word 
for hair, because of their extreme smallness. Their usual 
diameter is not more than -juVo" °f an inch. But they make 
up in numbers what they lack in size, for they are so thickly 
distributed that there is scarcely a point on the body where a 
fine needle could be inserted without puncturing one or more 
of them. They are found in every tissue of the body except 
in the nails, hair, epidermis, and cornea of the eye. Their 
walls are a thin, transparent membrane, through which liquids 
and gases may freely pass. They are thus important agents in 
absorption. (See Digestive System.) 
The blood which passes into the capillaries throughout the 
tissues of the body from the systemic arteries is of a bright red 
color, but after it has gone through and reached the veins it is 
darker and has lost certain elements and gained others. * The 
capillaries which terminate the pulmonary artery, however, re- 
ceive dark blood and deliver it in a bright red condition to the 
pulmonary veins. These changes of material will be explained 
under other headings. Suffice it to say here, that through the 
capillary walls all the important changes of material take place. 98 
LESSONS IN PHYSIOLOGY. 
8. The walls of the larger veins and arteries are supplied 
with small arteries and veins. These are called vasa vasorum 
(vessels of the vessels). The walls of the small blood-vessels 
are supplied from the blood in the vessels themselves. 
PRACTICAL ILLUSTRATIONS. 
1. Cut off two or three inches from the aorta of an ox, sheep, or pig. Remove 
all fat, and place it in a cup of water for several days. You may then separate 
by carefully working with a dull knife the three coats of the vessel. The outer 
coat can he turned back on the others as you would turn up the sleeve of your 
coat. Then the middle coat may he turned hack on the inner coat in a similar 
manner. 
2. Test the elasticity and strength of arteries by pulling and stretching a 
piece of the aorta. Compare a piece of the aorta with a section of the vena 
cava. Both vessels may be obtained from the heart and lung specimen (or a 
similar one), mentioned in a former lesson. 
3. Instruct pupils to find the following arteries on their own persons by 
feeling the pulsation with the finger: The radial artery at the wrist near the 
base of the thumb ; the ulnar on the inner, or little finger, side of the wrist; the 
carotid artery at the side of the neck just below the angle of the jaw; the tem- 
poral on the temple just in front of the top of the ear ; the facial on the lower 
jaw exactly half-way between the chin and the angle of the jaw; a branch of 
the facial by holding the lower lip at the corner of the mouth between thumb 
and finger; another branch by holding the upper lip in the same manner; the 
supra-orbital on the edge of the frontal bone just above the centre of the eye ; 
the infra-orbital on the malar bone at a point just below the centre of the eye. 
There are many other places where arteries may be felt pulsating, but these are 
sufficient to illustrate the fact that arteries, although mainly lying deep in the 
tissues, at certain points appear near the surface. 
4. The presence of valves in the veins may be proven on the back of the 
hand in some persons. Find a place where the vein stands out prominently; 
wet the finger and rub along the course of the vein in a direction opposite to that 
in which the blood flows, or away from the heart, and keep the finger firmly 
pressed on the vein. The finger will push the blood out of that part of the vein 
over which it passes, and if there be a valve in its course, the blood will be seen 
coming back up to that point but no further. This shows that blood may flow 
backward; that is, away from the heart, but only to a point where a valve 
occurs. THE BLOOD AND ITS CIRCULATION. 
99 
LESSON 19. 
The Blood and its Circulation. 
1. The blood in the human body amounts to about one-eightli 
of the weight of the body, or in a person of average size, to 
about 2\ gallons. 
2. Physical Properties. — Blood is a little heavier than water, 
and is of a bright scarlet color in the systemic arteries, and a 
very little darker in the systemic veins. It is salty to the taste, 
and has an odor peculiar to itself. Shortly after being drawn 
from the body it coagulates, or clots, and becomes thick like 
jelly. 
3. Composition of Fresh Blood. — To the unaided eye, or in 
quantity, the blood appears to be a simple liquid of a red color, 
but if a little be spread very thinly on a glass slide, and ex- 
amined with high power of the microscope, it is seen to consist 
of a clear liquid in which numbers of little roundish bodies are 
floating. These are usually called blood corpuscles (little 
bodies). The greater proportion of the corpuscles appear 
faintly red or yellowish when seen singly, but when many are 
together the mass appears red. A few of the corpuscles are 
whitish, or nearly culorless. 
The colorless liquid in which the red and white corpuscles 
float is called plasma, or liquor sanguinis. It is the nourishing 
part of the blood, but also contains waste matter of the body. 
It is composed of proteid, or albuminous matter, mineral salts, 
and water. Also a small proportion of certain gases. The red 
corpuscles contain a substance which gives them their charac- 
teristic color. It is called hemaglobin. It is a complex chem- 
ical substance, containing iron in combination. The white 
corpuscles are supposed to be simply masses of protoplasm. 
(See Introduction.) 
4. The Corpuscles. — These are interesting little bodies, and 
deserve further notice in this connection. The red ones when 
lying flat appear as circular discs, but when seen in profile are 
slightly concave on both sides, bearing no little resemblance to 100 
LESSONS IN PHYSIOLOGY. 
a biscuit or cracker. They are about of an inch in diam- 
eter in man, but many times larger in some of the lower ani- 
mals. In the proteus, a species of salamander resembling a 
lizard, they are large enough to be seen by a common pocket 
magnifying glass, being more than sixty times as large as in 
man. In a few animals they are smaller than in man. In the 
reptiles and frogs they are oval in shape and have a distinct 
nucleus. Some notion of the minute size of the corpuscles in 
Fig. 14. — The Circulation in the Capillaries of the Web of a Frog’s Foot, 
AS SEEN UNDER THE MICROSCOPE. 
1, Blood corpuscles; 2, Pigment matter. 
man may be had when we say that were they laid closely side 
by side, it would take twelve millions of them to cover a square 
inch of surface. When spread upon the glass they often col- 
lect in rows appearing like so many coins leaning against each 
other. 
The white corpuscles vary in proportion to the red. Some- 
times there are only as many white as red ones, and again 
there are as many. The white corpuscles, unlike the red, 
have no definite shape; in fact, they may be seen to change THE BLOOD AND ITS CIRCULATION. 
101 
their shape apparently at will. In their motions they resemble 
one of the lowest forms of animals, called the amoeba. This 
animal is a mere shapeless mass of living matter (protoplasm). 
When it wants to move it merely pushes out a part of itself, 
and the remainder of the body slowly draws up to it. It may 
push out parts of itself in several directions at the same time, 
and assume a great variety of irregular forms. Exactly similar 
actions have been observed in the white corpuscle, and its 
movements are therefore called amoeboid movements. Under 
certain conditions they actually pass through the capillary 
walls, although no openings discernible by the highest powers 
of the microscope exist. A minute, thread-like portion appears 
on the opposite side, and this enlarges while that on the other 
side diminishes, until the entire mass has passed through. 
This is called diapedesis, or migration of the white corpuscles. 
5. The Origin, Destiny, and Use of Corpuscles. — We know noth- 
ing definite as to the origin of the corpuscles. That they are 
formed in the spleen, lymphatic glands, and in the red marrow 
of the bones is an opinion which has not been proven a fact. 
It is thought that the white are simply an earlier stage in the 
formation of the red ones, but this is not settled. As to their 
destiny we are also in the dark. From fragments having been 
found in the spleen, it was thought that they were destroyed 
in that organ, and the spleen has been designated “ the grave of 
the red corpuscles.” 
As to their use, we have more definite knowledge, especially 
of the red ones. The hemaglobin of the red corpuscles unites 
with oxygen in the lungs, and again gives it up throughout the 
tissues of the body. They are therefore carriers of oxygen gas 
which is necessary in the vital processes. The white corpuscles 
are always found to be more abundant near a wound which is 
in the process of healing, and they are identical in appearance 
and actions with the corpuscles found in chyle and lymph. It 
is a reasonable supposition that they are early stages of living 
cells, and are closely connected with the processes of growth 
and repair of the tissues. 
6. Coagulation. — If blood be drawn from the living body and 102 
LESSONS IN PHYSIOLOGY. 
allowed to stand in a vessel, in about ten minutes it begins to 
separate into two distinct parts, one a clear, watery liquid, the 
other a thick, jelly-like, dark red mass. The watery liquid is 
called the serum. It must not be confounded with the plasma. 
It is plasma minus corpuscles and a substance called fibrin. 
The coagulum, or clot, is the name applied to the jelly-like por- 
tion. It consists of fibrin, which has entangled in its meshes 
the corpuscles. By repeated washing in clean water the cor- 
puscles may be dissolved out, leaving the fibrin a white, stringy 
substance. Blood may be kept from coagulating for a time by 
the addition of certain chemical substances, or by a certain de- 
gree of cold. In this case the corpuscles prove themselves to 
be slightly heavier than the plasma by slowly settling to the 
bottom of the vessel. If fresh blood be beaten with twigs in 
the same manner as one would beat an egg, the fibrin will col- 
lect on the twigs as a stringy substance. If a portion of a large 
blood-vessel be tied in two places, while full of blood, and then 
separated from the animal, the blood will remain for an indefi- 
nite time in this tube, uncoagulated. If needles be thrust into 
a living blood-vessel, the fibrin will form and gather on them. 
These and other experiments have been tried on animals to dis- 
cover the cause of coagulation, but as yet nothing very satisfac- 
tory is known. It has been proven that the blood contains three 
elements, all of which are necessary for its coagulation. 
But whatever the cause of coagulation may he, its importance 
to the animal being is undoubted, for it is nature’s method of 
arresting hemorrhage. When blood-vessels are cut or torn so 
that blood begins to escape, coagulation soon closes the open- 
ings in the vessels, unless the vessel be a very large one, in 
which case, unless artificial means are applied to stop the flow 
of blood, the animal will die of hemorrhage. In some of the 
lower animals coagulation takes place much more quickly than 
in man, and bleeding is seldom fatal among them. In birds 
the blood coagulates almost instantly after leaving the vessels. 
7. The General Course of the Blood. — Starting with the capilla- 
ries throughout the body, let us trace the blood in the round of 
the circulation. From the capillaries it passes into the veins, THE BLOOD AND ITS CIBCULATION. 
103 
which grow larger and fewer until the heart is reached by two 
main trunks, already described. These empty the blood into 
the right auricle. From here it passes into the right ventricle. 
By the contraction of its walls it is forced into the pulmonary 
artery, which, by its numerous branches, conveys it to the 
capillaries of the lungs. Thus far it is dark colored, or venous 
blood. In the capillaries of the lungs it receives oxygen and 
parts with carbon dioxide, and appears in the branches of the 
pulmonary veins of a brighter red color. It is now arterial 
blood, although the vessels containing it are called veins. The 
pulmonary veins convey the blood to the left auricle, from 
whence it descends into the left ventricle. By the contrac- 
tions of the powerful muscular walls of the left ventricle, it is 
sent with great force into the aorta, and through it into its 
branches, until it reaches again the capillaries of the body, the 
place from which we started. In the capillaries it becomes 
dark again by the loss of oxygen and the gain of carbon dioxide. 
It must be remembered that the veins are those vessels which 
carry blood to the heart, and the arteries are those vessels which 
carry blood from the heart. The veins, with the exception of the 
pulmonary, carry dark, or venous blood; the arteries, with the 
exception of the pulmonary, carry bright red, or arterial, blood. 
8. Special Circulations. — The course of the blood, from the left 
ventricle through the body and back to the right ventricle, is 
called the systemic circulation. The flow from the right ven- 
tricle to the lungs and back to the left ventricle is called the 
pulmonary circulation. The passage of the blood through the 
capillaries is sometimes distinguished as the capillary circula- 
tion. The blood which is distributed to the stomach, spleen, 
and intestines, is carried by the portal vein to the liver and 
spread through its tissues, to be gathered up again by the 
hepatic veins and returned to the vena cava. This is called the 
portal circulation. 
9. Causes of Circulation. — The primary cause of circulation is 
the muscular contraction of the heart. When the heart stops 
beating the blood soon ceases to move in the vessels. The heart 
acts like an engine or force-pump, sending a constant supply of 104 
LESSONS IN PHYSIOLOGY. 
blood into the vessels and keeping it there under pressure. 
That the heart exerts an influence beyond that of merely 
throwing the blood into the aorta, is shown by the fact that the 
arteries, down to the smallest, can be felt and seen to throb and 
pulsate with every beat of the heart. "This “pulse,” as it is 
called, may be felt under certain circumstances, even in the 
veins. With every contraction of the heart, a wave-like motion 
is started in the blood and becomes less and less perceptible, 
the farther away and the smaller the artery. It is somewhat 
like the ripple produced upon a pond by dropping a stone in the 
water. Thus by feeling the pulse at the wrist, or on the tem- 
ples, the physician can tell how rapidly and how strong the 
heart is contracting. If the heart is beating feebly and slow, 
Fig. 15. — Sphygmograph tracing of Pulse. 
the pulse will feel weak against the finger, and the number of 
beats per minute will correspond exactly to the number of heart- 
beats in the same time. 
There are other circumstances which modify and aid in the 
circulation. Among these may be mentioned: (1) the elastic- 
ity of the arteries; (2) the muscular contractions in the coats of 
the arteries; (3) the pressure caused by the movements of the 
muscles upon the veins, aided by their valves; and (4) possibly 
capillary attraction in the smallest vessels, and osmose, or the 
force which causes the flow of fluids and gases through the Avails 
of the capillaries, both into and out of the vessels. 
10. The Sphygmograph. — This is a strange looking word, but 
it means simply the “ pnlse-writer. ” It consists of a lever so 
arranged that the pulse in the wrist can move it up and down THE BLOOD AND ITS CIRCULATION. 
105 
freely, and at the same time its point is made to press upon a 
piece of smoked paper, made to move at a regular rate by clock- 
work. When applied to the wrist and set in motion, the lever 
writes a wavy line as shown in the cut, which is an accurate 
copy of the writing made by the pulse of the author of this book. 
This instrument shows the condition of the Circulatory System, 
for marked differences exist between the pulse of health and 
that of disease. It is therefore a valuable aid to the physician. 
The highest part of the line represents the contraction of the 
ventricles, and the wavy slope shows their dilation and the re- 
sistance to the flow in the arteries. The variations in these 
curves show the variations in force, frequency, and regularity of 
the heart-beats and the degree of arterial resistance, points of 
great value in determining disease and its treatment. 
11. Rate of Circulation. — A given portion of the blood may- 
make the complete circuit of the body; that is, from the veins to 
the right side of the heart, thence to the lungs, back to the left 
side of the heart, thence to the arteries, and through the capil- 
laries to the veins again, in the short space of twenty-four sec- 
onds. Experiments on various animals have been made to ascer- 
tain this. Certain chemicals which can be easily detected by a 
test are introduced into a vein on one side of the neck, then 
blood is drawn at different intervals of time from a vein on the 
other side of the neck, and tested for the chemical. It is esti- 
mated that the entire amount of blood in a man makes a com- 
plete circuit of the body every two minutes. 
PRACTICAL ILLUSTRATIONS. 
1. Procure from a slaughter-house a small quantity of the fresh blood of an 
animal. It will very probably have coagulated before you reach the school- 
room. Place a little of the clot in a clear glass bottle, and add water. Shake 
vigorously, and observe that the water becomes intensely red. Then pour out 
the water and add more. Shake again and pour off the reddened water. Repeat 
this process many times. Observe that the clot becomes smaller and the edges 
become white. This white substance is fibrin. By repeated washings a small 
quantity of pure fibrin may be obtained. The water has been made red by the 
corpuscles which have separated themselves from the clot. 106 
LESSONS IN PHYSIOLOGY. 
2. The principle of the sphygmograph may be shown by laying the hand and 
arm palm upward on the table and balancing a pencil on the radial artery in 
the wrist. Observe that the pencil moves up and down with every pulsation. 
This motion may be magnified so that it can be seen by a large audience. Fasten 
a bit of looking-glass to one end of the pencil and balance it on the pulse, hold- 
ing the hand in the sunlight in such a position that the mirror will reflect a spot 
of light on the wall or ceiling. The spot will vibrate back and forth through a 
considerable space with every beat of the heart. It may not be possible to per- 
form this experiment with every person, as in some the artery lies too deep to 
move the pencil. 
3. To show the corpuscles of the blood requires a microscope such as the 
majority of teachers or schools are not likely to be provided with. To those 
teachers who are fortunate enough to possess or have access to a good micro- 
scope, the following hints may be of value: — 
Tie a string tightly around the finger. In a moment the finger swells and 
becomes red. Prick with a needle slightly. Touch the drop of blood which 
appears lightly with the surface of a glass slide. Blow off or shake off the super- 
fluous blood so as to leave only a stain on the glass. Place at once under the 
microscope, turning on a good light. The red corpuscles will be seen in great 
numbers, and probably a few white corpuscles may be seen. They will be 
known by the white appearance and generally irregular form. If possible pro- 
cure a live frog, turtle, or salamander, and place a drop of its blood under the 
microscope. Note the oval shape, the great size, and the nucleus. 
The circulation of the blood in the web of a frog’s foot is a very interesting 
and instructive sight. The frog may be placed in a box along with a cloth 
saturated in chloroform. As soon as he shows signs of unconsciousness he 
should be removed and placed on a thin board with a small hole cut in one 
corner. Fasten the board to the stage of the microscope so that the hole comes 
under the lens. Spread out the web of the frog’s foot over the hole, and fasten 
by pins placed against, not through, the toes. Keep the body of the frog covered 
with a wet cloth. 
An instructive and beautiful object is the egg of a carp just about to hatch. 
They may be procured frequently from artificial fish ponds, adhering to weeds 
and sticks in May. If procured at the proper time, the young fish may be seen 
curled up in the egg, the whole being so nearly transparent that the blood may 
be seen flowing from the heart to all parts of the body and back again to the 
heart. 
LESSON 20. 
The Lymphatic System. 
1. The Lymphatic System, sometimes called the Absorptive 
System, is accessory to the Circulatory System, and consists of: THE LYMPHATIC SYSTEM. 
107 
(1) lymphatic vessels with their contents, lymph, and chyle 
and (2) lymphatic glands. 
2. Lymphatic Vessels. — These are a series of minute, delicate, 
transparent tubes of nearly uniform thickness, but having a 
knotted appearance, due to valves in their interior. They are 
found in nearly every part of the body, except the brain, spinal 
cord, eyeballs, tendons, cartilages, nails, epidermis, and hair. 
They are divided into: (1) superficial, lying just beneath the 
skin and near the surfaces of the great cavities of the body; 
(2) deep, accompanying the deep blood-vessels. They are 
more numerous than the veins and anastomose more fre- 
quently. 
3. Thoracic Duct and Right Lymphatic Duct. — All the lym- 
phatic vessels except those of the right side of the head, neck, 
and chest, right arm, lung, and upper surface of the liver, empty 
into one common trunk, called the thoracic duct. It is from 
eighteen to twenty inches long, one-quarter of an inch thick, 
and extends from the second lumbar vertebra to .the seventh 
cervical, where it empties into the left subclavian vein. At its 
lower extremity is a bag-like enlargement, called the receptac- 
ulum chyli (receptacle of the chyle). Those lymphatic vessels 
which do not empty into the thoracic duct, empty into a short 
trunk, one inch in length and about one line in thickness, 
called the right lymphatic duct. It empties into the right sub- 
clavian vein. 
4. The Lacteals. — Although described with the digestive 
organs, they should be mentioned here as a part of the Lym- 
phatic System. They consist of those lymphatics which are 
distributed to the small intestine, and end in the villi already 
described. They differ from the other lymphatics only in that 
they carry chyle instead of lymph. 
5. Lymphatic Glands. — These are small bodies, varying from 
the size of a grain of wheat to the size of an almond, and are 
pinkish gray in color. They are found in the course of the 
lymphatic vessels, in various parts of the body, but more nu- 
merous in the neck, armpits, space behind the knee, groins, and 
in the folds of peritoneum which hold the intestines in place. 108 
LESSONS IN PHYSIOLOGY. 
We are often made aware of their existence by their becoming 
swollen and enlarged. The lymphatic vessels pass into the 
glands, divide into branches, and unite again as they pass out. 
Their function is not certainly known. They have been sup- 
posed to be concerned in the production of blood corpuscles. 
6. Lymph, Chyle, Blood, Plasma, Serum. — Five fluids of impor- 
tance which the pupil should understand. The lymph is the 
clear fluid found in all the lymphatics (except the lacteals, dur- 
ing digestion). It is poured into and becomes a part of the 
blood in the manner already described. It contains some white 
corpuscles, but rarely, if ever, red ones. The chyle differs in 
no way from lymph except that it contains fat globules, which 
give it a milky white appearance. It is found in the lacteals 
and thoracic duct, during and after the digestion of a meal. 
When emptied into the blood-vessels it loses its identity and 
becomes a part of the blood. The blood in the living vessels 
consists of plasma and corpuscles. Plasma and lymph are 
scarcely distinguishable. Plasma will coagulate, producing 
fibrin and serum. Serum in any considerable quantity is not 
found as a normal constituent of the body. It is a result of 
coagulation of the blood, or some morbid change. It is the 
fluid of dropsy. When a blister is raised on the skin by heat or 
pressure or medicine, the clear fluid beneath the epidermis, or 
in the blister, is serum. It bathes the surfaces of all serous 
membranes. The term serum is used by some authors synony- 
mous with plasma, but a distinction should be made. The 
following formulated statements will assist the memory: — 
Lymph equals chyle minus fat. 
Chyle equals lymph plus fat. 
Plasma equals blood minus corpuscles. 
Fresh blood equals plasma plus corpuscles. 
Coagulated blood equals serum plus fibrin and corpuscles. 
Serum equals blood minus fibrin and corpuscles. 
7. Function of the Lymphatic System. — Tlie tissues, as we 
have learned, are constantly being torn down and rebuilt, and 
while the body is increasing in size, new tissues are forming THE LYMPHATIC SYSTEM. 
109 
in addition to those which replace the old. The material for 
this building and rebuilding is the plasma of the blood. It 
passes by the process known as osmosis through the capillary 
walls. The material of the old tissue, or a part of it at least, 
passes back through the capillary walls by the same process, 
and produces the change from arterial, or red blood, to venous, 
or dark blood. But in this flow of plasma through the capil- 
lary wall there is a surplus which the tissues cannot use. 
This, with possibly a part of the waste material which is not 
returned to the blood in the capillaries, passes into the lym- 
phatic vessels and constitutes the fluid known as lymph, which, 
as we have seen, is returned again to the blood through the 
two main channels, the thoracic and right lymphatic ducts. 
The lymphatics proper, therefore, are for the collection of the 
overflow of the blood-vessels, and possibly, to a certain degree, 
for the return of waste material to the veins. The function 
of the lacteals has been given under the Digestive System. 
The function of the lymphatic glands is not certainly known. 
As the lymph all passes through them, we suppose that they 
produce some change in it which prepares it for nourishing 
the system. 
8. The Thymus and Thyroid Glands. — In this connection we 
may mention two peculiar bodies which have received the name 
of glands, although their use is not known. They are regarded 
as appendages of the Lymphatic System. The thymus gland is 
a small body found just above the heart. It reaches its greatest 
size at about the age of two years, and then becomes smaller 
and almost disappears in the adult. The thyroid gland lies 
in front of the neck just beneath the skin, in front of the 
windpipe. It becomes greatly enlarged in the disease known 
as big neck, Derbyshire neck, or goitre. This disease is 
occasionally seen in this country, but in certain mountainous 
portions of Europe it is exceedingly common. The gland 
becomes sometimes as large as one’s head, and may interfere 
with breathing. 110 
LESSONS IN PHYSIOLOGY. 
LESSON 21. 
Hygiene of the Circulation. 
1. Wounds and Bleeding. — A very slight wound may bleed 
profusely and appear to be very serious, and again, a wound 
may be deep and severe and appear to be but slight. Examine 
a wound carefully. Observe if the blood flows steadily and 
is dark in color. If so, only veins are injured, and the 
danger is not so great from hemorrhage. Should the blood 
flow very rapidly try to stop it by tying a bandage (a handker- 
chief will do) loosely around the limb, pass a stick through the 
loop and twist the bandage until it is drawn tightly to the part. 
It must be remembered that the blood in the veins flows 
toward the heart, and the bandage must be put on the side of 
the wound furthest from the heart. Should the blood flow in 
spurts or jets, and be bright red in color, an artery is injured, 
and no time should be lost in placing a bandage on the side 
nearest to the heart. If the flow of blood is considerable, 
send at once for a physician, but keep trying to stop the flow 
of blood by the bandage and stick. In some cases, as in the 
palm of the hand, it will be best to place a piece of wood, a 
cork, or a wad of cotton or rags in the wound, then pass the 
bandage directly over this and apply the pressure by twisting. 
Where many small 
blood-vessels are in- 
jured, some astrin- 
gent substance, as 
powdered alum, may 
be applied to the 
wound, or cotton, 
lint scraped from a towel, cobwebs, or some similar substance, 
may be applied to the wound. Many a soldier on the battle- 
field has saved his life, or at least prevented serious loss 
of blood, by applying dry earth to the wound. Bleeding from 
slight wounds may often be arrested by plunging the part in 
cold water or bv tving- a bandage tieditlv over it. 
Fig. 16. — Handkerchief and Stick Bandage. HYGIENE OF THE CIRCULATION. 
When a person spits or vomits blood, it is important to 
know if it come from the lungs or from the stomach. If from 
the latter it will be dark and probably mingled with food. If 
from the former it will be lighter in color and frothy. In 
either case, give some vinegar or lemon juice, and consult a 
physician. Bleeding from the nose is often quite serious with 
some persons, and it is difficult to check it. Bathing the face 
and neck in cold water and holding the arms high above the 
head for a few minutes will often succeed. If these do not, 
pour a solution of alum into the nostrils. If not stopped soon 
send for the physician. 
2. Effects of Nervous Shocks on Circulation. — The circulation 
of the blood is controlled entirely by the Nervous System, and 
as a general rule the action is automatic; that is, an uncon- 
scious stimulus passes from the brain, causing the heart to beat 
with a certain degree of regularity and force; but strong emo- 
tions, as of fear, anger, etc., cause special stimuli to pass along 
the nerves to the heart, and induce irregularities in its action. 
Certain mental states affect also the small arteries and the 
capillaries. Blushing and pallor are due to relaxations and 
contractions in the muscular fibers of the blood-vessels, caused 
by mental conditions. 
Frequent disturbances of the regularity of the circulation 
cannot occur without injury to the system. Causes of shocks 
and nervous excitements should be avoided. 
3. Effects of Cold and Heat on the Circulation. — Cold tempo- 
rarily increases the circulation, but if continued tends to check 
it unless counteracted by exercise and stimulants, which may 
keep it up for a time. Heat also increases the circulation 
within certain limits only. Coldness of the feet and hands is 
generally due to insufficient circulation of blood through them, 
and this deficiency of circulation is often brought on by exter- 
nal cold in the first place. Hence the importance of keeping 
the extremities properly clothed in cold weather. 
4. Exercise and the Circulation. — Count your pulse when at 
rest; then exercise vigorously for a few minutes and count it 
again. You will observe a perceptible increase in the number 112 
LESSONS IN PHYSIOLOGY. 
of beats per minute. Every jiart of the body should have 
exercise, that the blood may flow more freely to all parts. 
When the feet begin to get cold a vigorous and constant work- 
ing of the toes will soon make them warm, because the exercise 
increases the flow of blood to the parts. 
5. Alcohol and Tobacco and the Circulation. — The first effect 
of alcohol upon the circulation is to increase it generally. The 
heart beats more rapidly and with greater force, the arteries 
expand, and more blood is sent to the capillaries. A sensation 
of warmth and an increase apparently of strength throughout 
the system is the result. There is, however, no actual gain 
of strength, but rather a loss. It has caused strength to be 
expended, and like a fever is followed by corresponding de- 
pression and weakness. Frequent stimulations of this kind 
cause permanent dilation of the arteries and capillaries. It is 
this enlargement of the capillaries of the face that cause the 
red nose and face of the habitual drinker. It is true that under 
some circumstances of disease an artificial stimulus of the 
circulatory organs is a good thing, and the wise physician often 
makes use of alcohol to the great advantage of the patient, but 
in a state of health this undue excitement is injurious. Long- 
continued use of alcoholic drinks may cause fatty degeneration 
of the heart. Many men who are supposed to be temperate 
users of alcoholic drinks appear to be healthy until about the 
age of fifty, when they suddenly decline, the cause being a 
weakness of the Circulatory System in many cases. The heart 
has reached the limit of the unnatural strain put upon it. This 
weakness of the Circulatory System, due to alcohol, explains in 
the main why drinking men generally succumb to the attacks 
of epidemic diseases like cholera. The circulatory forces are 
not sufficient to expel the poisons from the blood. 
Excessive use of tobacco is apt to produce a form of palpita- 
tion of the heart. This condition is often spoken of by doctors 
as the “tobacco heart” or the “smoker’s heart.” HYGIENE OF THE CIRCULATION. 
113 
EXERCISES FOR REVIEW. 
1. What is the probable amount of blood in your body ? 
2. How does fresh blood differ from blood which has been drawn from the 
vessels for some time ? 
3. What is the use of the red corpuscles ? What gives color to the blood ? 
4. Name and classify the cavities of the heart. Name and locate the valves 
of the heart. 
5. What are the motions of the heart ? 
6. In what is the heart enclosed ? 
7. What holds the heart in its position ? 
8. If you were to tie a string very tightly around an artery, what coats would 
be severed ? 
9. What is the sphygmograph ? What is its value ? 
10. Trace a particle of blood from the little finger of the right hand until it 
reaches the capillaries of the lungs, naming the principal parts through which it 
must pass. Trace in a similar manner a particle of blood from the capillaries 
of the lungs to the great toe of the left foot. [The teacher may assign other 
routes for the pupils to trace out.] 
11. Name some points of resemblance and some of difference between arteries 
and veins. 
12. What is the use of the pericardium ? Of the mitral valve ? Of the semi- 
lunar valves ? Of the tricuspid valves ? Of the valves in the veins ? 
13. What are vasa vasorum ? 
14. Describe the portal circulation. Compare with Functions of the Liver. 
15. How do chyle and lymph differ from each other ? Compare plasma and 
serum. 
16. What advantage does the animal derive from coagulation of the blood ? 
17. Where place the bandage in case you wish to stop the flow of blood from 
a wounded artery ? In case of a wounded vein ? 
18. Explain the red nose of the drunkard. 
19. How do the muscles aid in the circulation ? 
20. What is meant by anastomosing of the blood-vessels ? What advantage 
is there in it to the individual ? 
21. How is the Circulatory System related to the Digestive System ? 
22. Can human blood be distinguished from the blood of an animal ? It 
can by the microscope be distinguished from the blood of reptiles, fishes, birds, 
and some mammals by the difference in size and shape of the corpuscles, but it 
cannot be distinguished from that of the dog, pig, and some other mammals. 
This is an interesting medico-legal question. CHAPTER III. 
HOW GASES ARE EXCHANGED IN THE BODY, OR THE RESPIRA- 
TORY SYSTEM. 
LESSON 22. 
Organs of Voice and Respiration. 
1. Oxygen is necessary to tlie existence of all animals. As 
this gas exists free in the air there must be some mechanism 
whereby air can be taken into the body. In the lower forms of 
animal life very little oxygen is needed, and the quantity found 
dissolved in water is sufficient for many species. In some eases 
it passes through the skin directly into the blood, in others it 
goes in with the water which circulates through the animal or 
mingles with its blood. In others again, little openings in vari- 
ous parts of the body admit air to tubes which ramify through 
the body. In fishes and some others the oxygen is absorbed 
from the air contained in the water by means of gills which are 
similar to lungs. All higher animals have lungs more or less 
perfect. Yet a variable quantity of oxygen is taken in through 
the skin in all animals, even in man. Those animals which 
make sounds by means of a modification of the respiratory 
organs are said to have voice. The organs of voice and respira- 
tion are therefore necessarily closely connected. 
2. The Larynx. — The air is received from the nasal passages 
or mouth into the pharynx, which has already been described. 
From this chamber it passes into the larynx, a short tube or 
box composed of cartilage and membrane. It forms the lump 
in the neck so prominent in lean persons, called “ Adam’s 
Apple.” The cartilaginous portion is in nine pieces. The 
largest is called the thyroid (shield-like) cartilage. It may be ORGANS OF VOICE AND RESPIRATION. 
115 
felt in the neck as the prominent point of the Adam’s Apple. 
It forms the main part of the larynx. It is largest above and 
unites below with the cricoid (ring-like) cartilage. This is 
somewhat like a seal ring, having the broad portion behind. 
The arytenoid cartilages, two in number, are small, triangular 
pieces placed upon the broad part of the cricoid. To each of 
the arytenoid cartilages is attached a very small cartilage called 
cornicula laryngis. The cuneiform are two small cartilages, 
one on each side of the arytenoid. The epiglottis is a single 
cartilage just behind the tongue, attached to the thyroid some- 
what like a trap-door. When the air is passing through the 
larynx, the epiglottis stands vertically, its free extremity curv- 
ing forward toward the base of the tongue. During the act of 
swallowing it is carried downward and backward so as to com- 
pletely close the glottis, or upper opening of the larynx. 
The vocal cords are two ligaments covered with mucous mem- 
brane passing from the fixed thyroid cartilage in front to the 
movable arytenoids behind, across the sides of the cavity of the 
larynx, leaving a space of varying size between them, called 
the rima glottidis. A little above the vocal cords are two ridges 
or elevations, which have received the name of the false or supe- 
rior vocal cords. Little muscles passing from the thyroid and 
cricoid cartilages to the arytenoid are capable of separating and 
approximating the points to which the cords are attached, 
and thus altering the size of the rima glottidis and changing the 
tension of the cords. 
3. The Trachea, or wind-pipe, extends from the larynx down- 
ward about four inches and divides to form the bronchial tubes, 
or bronchi. The trachea is a peculiar tube, so constructed as to 
combine the proper amount of flexibility with sufficient rigidity 
to remain an open tube under all circumstances. It is composed 
of incomplete rings of cartilage, from sixteen to twenty in num- 
ber, and held together by fibrous membrane. The rings surround 
about two-thirds of the tube, leaving a space at the back com- 
posed entirely of fibrous tissue with a few muscular fibers. Its 
diameter is about three-fourths of an inch. 
4. The Bronchi. — The right bronchus, or branch of the tra- 116 
LESSONS IN PHYSIOLOGY. 
chea, is a little shorter and wider and is placed more horizon- 
tal than the left bronchus. Each bronchus divides and subdi- 
vides many times, exactly like the branches of a tree, and thus 
penetrates every portion of the lungs. In structure the bronchi 
are somewhat similar to the trachea, being made up of fibrous 
membrane and cartilaginous imperfect rings. 
5. A continuous layer of mucous membrane lines the larynx, 
trachea, and bronchial tubes. The mucous membrane of the 
trachea and bronchial tubes is thickly set with what the anato- 
mist calls ciliated epithelium; that is, a layer of cells, each of 
Fig. 17. — Main Organs or Circulation and Respiration. 
1. The Larynx, Trachea, and Bronchi, deprived of their fibrous covering, and with 
the outline of the lungs. 2. A view of the Bronchi and Blood-vessels of the 
Lungs, as shown by dissection, as well as the relative position of the lungs to the 
heart. 
which has several exceedingly fine, hair-like projections. These 
projections are called cilia. They have the peculiar power of 
moving all at the same time and in one direction, so that if 
small particles be placed on them they are carried along like a 
boat in the current. This motion is always toward the mouth. 
In this way foreign particles, as dust, taken in with the air, are 
expelled. This motion is distinct from muscular movement. 
In many of the lower animals cilia play an important part in 
their life history. The oyster, and many other species of marine ORGANS OF VOICE AND RESPIRATION. 
117 
animals, swim about in the water by means of cilia when in a 
very young state, and when fixed for life in the adult stage 
currents, created by cilia, bring them their food. 
It must be remembered that mucous membrane lines all cavi- 
ties in the human body accessible to air. The mucus secreted 
acts as a protection from the irritating influences of the air. 
6. The Lungs.— The entire cavity of the chest, with the ex- 
ception of the comparatively small space occupied by the heart 
and its blood-vessels, and the esophagus, is filled by the two 
lungs. They even extend a little way into the neck. When 
the cavity of the chest is increased by the elevation of the ribs 
and lowering of the diaphragm, the lung-tissue expands and fills 
the enlarged space. They are in the shape of irregular cones 
with the apices above. The right lung has three lobes or divi- 
sions below, and the left two lobes. 
The lungs are a rose color, or light pink, in early life, but get 
darker as age advances. This dark color is more marked in 
persons who dwell in large cities or near factories, where the 
atmosphere contains much coal smoke. The color is due to par- 
ticles of carbon inhaled during life. 
The lungs are very light in weight by reason of the air in 
the cells. When once air has entered the air-cells a certain 
portion always remains, so that the lungs of an animal which 
has once breathed will always float in water. 
7. Structure of the Lungs. — Following out the bronchial tubes, 
which are really a part of the lungs, we come to the smallest 
branches which are from yIt 1° ts an inch in diameter. These 
branches open into a collection of oblong vesicles, or tiny bags of 
membrane, called air-cells. These collections of air-cells are called 
lobules (little lobes). Hales estimated the combined surface of 
the air-cells at 289 square feet, and Lieberkuhn at 1500 square 
feet. Professor Flint thinks we cannot tell how near the truth 
these estimates are, but it is simply evident that the extent of 
surface is very great. Around each lobule is a fine net-work of 
capillaries, the terminations of the branches of the pulmonary 
artery, the beginnings of the pulmonary veins. A fine con- 
nective tissue holds all these vessels and air-cells and tubes 118 
LESSONS IN PHYSIOLOGY. 
together, and among them ramify arteries which supply the 
lung-tissue with blood, and lymphatic vessels permeate every 
part. 
8. The Pleura. — The cavity of the chest is lined, and the 
lungs are covered with a continuous, delicate, serous membrane 
called the pleura. It thus forms a complete sac, and its inner 
surfaces secrete a fluid which lubricates them and prevents 
chafing when the lungs move in the chest. When this mem- 
brane is inflamed, the disease is known as pleurisy. This dis- 
ease is liable to be brought on by exposure to cold and damp- 
ness. 
PRACTICAL ILLUSTRATIONS. 
1. Get a live mussel shell from a stream or lake. Place it in clear water in a 
shallow dish with a little sand in the bottom. Leave it undisturbed for an hour, 
then drop a little powdered indigo into the water close to the shell. You will 
soon observe two openings at one end of the shell, and a current of water, as 
shown by the particles of indigo, going into one and out of the other. With a 
small magnifying glass you may he able to see the cilia, which surround the 
openings and produce the currents. 
2. Get the lungs of any animal from a butcher. The trachea and larynx will 
usually be attached. The larynx differs so much in size and shape in different 
animals that only a general idea of the human larynx can be obtained. Its gen- 
eral construction of pieces of cartilage and membrane may be shown, and the 
epiglottis and vocal cords may be seen, but they differ considerably in different 
animals. The trachea differs mainly in size from that in man, and a good idea 
may be formed. Cut it through lengthwise and show the cartilaginous rings. 
3. Place a tube in the trachea and blow into the lungs. Observe their increase 
in bulk as the air passes into the cells. Cut off a portion of lung-tissue and 
throw it into water to show its extreme lightness. Cut through the mass of a 
lung to observe the cut ends of the bronchial tubes and arteries of different sizes. 
With a narrow knife-blade slit open a bronchial tube, folfowing it as far as 
possible into the minute branches. 
4. Make an artificial larynx to illustrate the action of the vocal cords thus : 
Over the end of a short tube about an inch in diameter tie two pieces of sheet 
rubber or gutta-percha so as to leave a narrow slit between them. By properly 
adjusting these bands and blowing in the other end of the tube, you will be able 
to produce a sound, which will be caused by the vibration of the bands and the 
column of air passing through the narrow slit. RESPIRATORY PROCESSES. 
119 
LESSON 23. 
Respiratory Processes. 
1. Respiration. — Breathing, or respiration, is the process of 
taking air into the lungs (inspiration) and. expelling it again 
(expiration). Respiration is mainly an involuntary or auto- 
matic process. We can voluntarily hold our breath for a time, 
but in a few seconds an uncomfortable feeling compels us to 
take in and expel air. An animal cannot live long after respi- 
ration has ceased. In cases of suspended animation, where the 
person is supposed to be dead, respiration seems to have entirely 
ceased, but a small amount of air is exchanged and breathing 
really goes on, although unperceived. 
2. The Mechanism of Inspiration is as follows: The air enters 
the lungs through the nose or mouth (or through an artificial 
opening in the trachea) by atmospheric pressure caused by en- 
largement of the cavity of the chest. When you lift one board 
of a pair of bellows you enlarge the cavity and the air is forced 
in at the opening by its pressure, just as water enters a bottle 
when it is thrust into the water. The chest is a piece of 
mechanism very similar to a pair of bellows. There are two 
chief means of enlarging the chest cavity: (1) By the descent of 
the diaphragm. This is a muscular partition across the cavity 
of the body, dividing it into two principal cavities, the thorax and 
abdomen. When at rest the diaphragm is convex on the upper 
side. It has a tendon in the central portion, and the fibers 
radiate from it to the walls of the chest. When these fibers 
contract they cause the diaphragm to become much flatter by 
pulling the central portion down. This has the effect of lower- 
ing the general level of the floor of the chest cavity. (2) By 
the elevation of the ribs. In the cuts of the skeleton you will 
observe that the ribs at rest have a general slope downward 
from the spinal column. In inspiration all of the ribs are raised 
a little, and the general effect is to throw them forward and 
spread them out, and thus the cavity of the chest is enlarged 120 
LESSONS IN PHYSIOLOGY. 
both from before, backward, and from side to side. The ribs 
are raised by the contraction of the external intercostal muscles, 
assisted by certain muscles of the back, neck, and shoulders. 
In forced, or labored, inspiration still other muscles come into 
action, but all have a tendency to elevate the ribs. 
3. Mechanism of Expiration. — In ordinary breathing expira- 
tion is mainly the elastic reaction of tissues. The diaphragm 
returns to its state of rest in a convex position by the reaction 
of the abdominal organs which have been compressed and 
pushed against the abdominal walls. The ribs are returned to 
their position by the elasticity of the sternum and costal carti- 
lages which they have bulged out. Likewise the tissues of the 
lungs, which have been stretched by the inrushing air, resume 
their original condition and aid in expelling the air. In forced 
and labored expiration the abdominal muscles come into play 
by forcing the contents of the abdomen up against the dia- 
phragm, and the internal i'ntercostals tend to pull the ribs 
down. 
4. Rate of Respiration. — A healthy adult breathes on an 
average eighteen times per minute. The rate of respiration is 
increased by food, exercise, moderate cold, stimulating medi- 
cines, and in certain conditions of disease; and is diminished 
by moderate heat, inactivity, depressing medicines, starvation, 
and in certain diseased conditions. The respirations are more 
frequent in children than in adults, and more frequent in women 
than in men. The rate rarely exceeds twenty-five per minute 
or falls below fourteen. A man breathes about nine million 
times in a year. 
5. Lung Capacity. — The lungs are capable of holding from 
300 to 320 cubic inches of air. There is always a portion of 
air which cannot be expelled by the most forcible expiration. 
This is called residual air. There is a large quantity which 
can be expelled by a forced expiration. This is called reserve 
air. A like quantity can also be taken in by a forced inspira- 
tion. This is called complemental air. The quantity actually 
moved in ordinary respiration is comparatively small and is 
called tidal air. The following table shows the relations of 
these various quantities: — RESPIRATORY PROCESSES. 
121 
Total Lung Capacity . . . . 
Residual Air 
u u 
Reserve Air 
u u 
Complemental Air 
... 90 “ 100 
u u 
Tidal Air 
u u 
The residual air slowly diffuses with the reserve air, and while 
it remains the same in quantity its quality does not deteriorate. 
The presence of the residual air prevents sudden variations in 
the temperature, kind, and amount of air inhaled. About every 
fifth respiration is more forcible than the others. 
6. Exchange of Gases. — Atmospheric air contains about four 
parts nitrogen to one part oxygen. The nitrogen is almost, if 
not completely inert, and serves only to dilute the oxygen, which 
is the great life-sustaining element in nature. The expired air 
contains about four or five per cent less oxygen than the in- 
spired air, and about four per cent more carbon dioxide (car- 
bonic acid gas), or to be more exact: — 
Oxygen. Nitrogen. Carbon dioxide. 
Inspired Air = 20.81 parts. 79.15 parts. .04 parts. 
Expired Air = 16.033 “ 79.557 “ 4.38 “ 
Thus we see that the lungs have taken oxygen from the air 
and given back carbon dioxide. Now this latter gas is pro- 
duced by the union of carbon and oxygen. This takes place in 
all ordinary combustion of fuel, since nearly all fuel is mainly 
carbon. We must not conclude, however, that the process of 
combustion in the body is exactly the same as in ordinary burn- 
ing of fuel. We know that outside of a living body it requires 
a temperature of more than 200 degrees to cause oxygen and 
carbon to unite, and that the temperature of the animal body 
seldom goes above 100 degrees. The carbon dioxide must be 
produced not by direct union of oxygen with carbon but by the 
breaking up of tissues of the body which contain carbon and 
oxygen. The oxygen which is taken in is probably used with 
the carbon and nitrogen of the food to form new tissues. 
7. Effects of Respiration on the Air. — We have observed else- 
where that the blood after passing through the capillaries of the 
lungs, and coming in contact with the air-cells, is returned to 122 
LESSONS IN PHYSIOLOGY. 
the heart much brighter in color. This is due to the oxygen 
which it has absorbed. A similar effect may be produced on 
venous blood by shaking it in a vessel containing pure oxygen 
gas. 
Besides carbon dioxide, the expired air contains various other 
ingredients which it did not before possess. Ammonia gas, 
which exists in ordinary atmosphere in only minute quantities, 
is found to be present in a greater proportion in air that has 
been breathed. Also various organic matters, which are be- 
lieved to be highly poisonous, when again inhaled in considera- 
ble quantities, are given off at each breath. It is not the carbon 
dioxide thrown off in breathing that is poisonous, but these 
organic matters, as is shown by the experiment of breathing an 
atmosphere containing one per cent of carbon dioxide with a 
corresponding diminution of oxygen, as compared to breathing 
atmosphere in which the carbon dioxide has been raised to one 
per cent by breathing. In the first case no perceptible effect is 
produced, but in the second much depression and uneasiness 
follows. 
8. Modified Respiratory Movements. — There are several com- 
mon phenomena connected with breathing which should be ex- 
plained in this connection. These are as follows : — 
Sighing, a long, deep inspiration, chiefly through the nose, 
followed by a shorter expiration. 
Yawning, similar to sighing, but longer continued, and the air 
drawn through the widely opened mouth. 
Hiccough, or liickup, a sudden inspiration caused by spasmodic 
contraction of the diaphragm and sudden closure of the glottis, 
the well-known sound being caused by the column of air strik- 
ing the closed glottis. It is sometimes difficult to control and 
becomes an alarming symptom, requiring medical skill. 
Sobbing, a series of short, convulsive inspirations with closure 
of the glottis. 
Coughing, a deep and long-drawn inspiration, followed by a 
closure of the glottis, and then by its sudden and forcible open- 
ing, allowing a blast of air to be driven through the mouth. It 
is sometimes an effort to expel some irritating foreign substance RESPIRATORY PROCESSES. 
123 
in the air-passages, sometimes caused by an accumulation of 
mucus, and again by an irritation in some remote part of the 
body, being an example of pure reflex action, which will be ex- 
plained in the chapter on the Nervous System. It is sometimes 
partly contagious, as in schoolrooms and assemblies the cough- 
ing of a few persons will be followed by that of a large number. 
To a certain degree only it is under control of the will. 
Sneezing, the same as coughing, except that the air is driven 
through the nasal passages instead of through the mouth. It 
is generally caused by some irritation in the nose, but it may be 
produced through the nerves of the eye by strong light. 
Laughing, an inspiration followed by a series of short expira- 
tions which set the vocal cords in vibration. 
Crying, similar to laughing, but with different facial expres- 
sions, and generally caused by opposite emotions. 
Hawking, a voluntary forced expiration directed towards the 
larynx and pharynx to clear them of some obstruction. 
Grunting, a short, voluntary expiration causing vibration of 
the vocal cords. Groaning is similar, but more or less involun- 
tary. 
9. The Vocal Sounds are made by expiratory efforts modified 
by the tongue, teeth, lips, larynx, and palate. 
PRACTICAL ILLUSTRATIONS. 
1. To illustrate how raising the ribs enlarges the chest cavity, get a flexible 
twig or piece of whalebone and form a hoop which will just encircle the chest 
closely, when placed somewhat diagonally, that is, with the front part lower 
than the back part. Then let some one hold the hoop against the body at the 
back, while you raise the front part so as to bring it on a level with the back 
part. Observe the increase of space between the front part of the hoop and the 
body. 
2. Procure a large pail nearly full of water, a common glass fruit-jar, a piece 
of rubber tube about two feet long, a bit of candle, and some lime-water. (The 
lime-water must be made by immersing a lump of quick or unslaked lime in 
water and allowing it to remain until it has settled. Then pour off the clear 
solution into a separate bottle.) With this material the following interesting 
experiments may be made: — 
a. Fill a glass fruit-jar with water by immersing it in a pail of water, and 
without taking it out invert it, and hold it so that only the mouth will be under 
water. The atmospheric pressure will sustain the water in the jar above the 124 
LESSONS IN PHYSIOLOGY. 
level of that in the pail. Now put one end of the rubber tube beneath the mouth 
of the jar, and the other end in your mouth, and slowly expel the air from your 
lungs until you have caught a jar full of expired air. In this way you get the 
expired air free from any mixture with the atmospheric air. Now place the palm 
of your hand under the jar and, holding it tightly (keeping the palm flat), place 
the jar right end up on the table, and keep the hand firmly pressed on the mouth 
until an assistant can hand you a piece of lighted candle fixed on a piece of wire. 
Then quickly remove the hand and slowly lower the candle into the jar. The 
candle will cease to burn in the expired air, since it has been deprived of much 
of its oxygen. 
To make this experiment a success you must take in a good breath and hold 
it for several seconds, and then exhale slowly through the rubber tube; other- 
wise the air will not have been sufficiently deoxygenated. 
b. Fill the jar with expired air as in a. On removing the hand pour in a little 
lime-water. Then replacing the hand shake vigorously for a minute. Observe 
that the clear lime-water becomes milky white. This is due to the carbon dioxide 
of the breath uniting with the lime to form carbonate of lime, which gives the 
milky precipitate. (Lime-water is thus a test for carbon dioxide.) 
c. Allow a bit of candle to burn for a minute or two in the bottom of a clean 
jar. Then remove it and pour in a little lime-water and shake as in experiment 
b. The clear lime-water becomes milky, showing that the product of combus- 
tion is the same (carbon dioxide) as the product of breathing. 
d. Modify experiment b by placing one end of the rubber tube in a bottle of 
clear lime-water, and breathing slowly through the other end. Result, a white 
precipitate of carbonate of lime same as in the other experiments. 
LESSON 24. 
Hygiene of Respiratory System. 
1. Necessity for Pure Air. — The blood needs oxygen. Pure air 
contains a sufficient quantity and the blood absorbs it in the 
lungs. If the air be mixed with other gases the amount of oxy- 
gen will be to that extent lessened. But unless these other 
gases be considerable in quantity the effect will not be percepti- 
ble. The greater danger lies not in the displacing of a small 
amount of oxygen, but in the substitution of gases injurious in 
themselves. Carbon dioxide, which is given off in the breath- 
ing of animals and in combustion and decay of organic matter, 
seems not to be injurious in itself, but displaces a certain amount 
of oxygen, yet the amount ordinarily displaced would hardly do HYGIENE OF RESPIRATORY SYSTEM. 
125 
any harm. Ammonia sometimes exists in considerable quantity 
in the air. It is irritating and injurious. So are some of the 
gases thrown into the air from factories of various kinds. Car- 
bon monoxide is a poisonous gas, sometimes produced in badly 
constructed cast-iron stoves, and when thrown into the atmos- 
phere of improperly ventilated rooms produces headache and 
dizziness. 
Air which has once been breathed is unfit for immediate res- 
piration because it contains certain organic substances which 
are poisonous. This exhaled air becomes purified by mingling 
with the mass of the atmosphere in various ways. Water and 
other liquids absorb some of the impurities. Plants take up a 
certain amount of the carbon dioxide, and all becomes so diluted 
by the atmosphere that only infinitely small quantities can be 
again inhaled where ventilation is perfect. 
By pure air, then, we mean air containing the average amount 
of oxygen, nitrogen, carbon dioxide, and watery vapor, and the 
absence of injurious gases and solids in the form of dust. 
2. Moisture in the Air. — All air contains more or less water 
in a state of invisible vapor. This can be shown by the simple 
experiment of filling a dry glass tumbler with ice-cold water 
and allowing it to stand for a few minutes in a warm atmos- 
phere. Moisture soon collects in drops on the outside* of the 
vessel, being condensed from the atmosphere. When air con- 
tains a very large amount of watery vapor it contains corre- 
spondingly less oxygen, hence the air seems heavy (although it 
is really lighter), because the respiratory apparatus must make 
greater effort to get the proper amount of oxygen for the blood. 
On the other hand, air which is too dry irritates the delicate 
structures of the lungs and air-passages. The air of rooms be- 
comes frequently too dry when heated by stoves. A vessel of 
water placed where it will evaporate rather rapidly will improve 
the quality of the air in such cases, but care must be taken to 
see that the water and the vessel containing it are clean. 
3. Dust and Disease. — Although we cannot see it always, the 
air contains at all times solid matter in the form of fine particles. 
When the sun shines through a small opening into a room we 126 
LESSONS IN PHYSIOLOGY. 
can see this dust, which is illuminated and appears as a bright 
band. Tyndall showed by illuminating the air by electric light 
that no air is free from dust. The dust consists of sand, clay, 
particles of carbon from smoke, fibers from clothing, hairs and 
epidermal scales from animals, particles of dried expectorated 
matter, and other objects. But the worst matter held in sus- 
pension is the minute germs or seeds of low orders of plants. 
These germs (generally called bacteria) are now shown to be 
the causes of most of the diseases which affect mankind. They 
find their way into the blood, and if they be numerous enough 
and the system in a proper condition for them, they grow and 
multiply, and this constitutes the disease, the different diseases 
being produced by different species of germs. The coarse par- 
ticles, when numerous, are also injurious, as they irritate the 
delicate membranes of the air-passages. Wherever air is known 
to be unusually full of dust and where disease germs are sus- 
pected, a filter of cotton wool placed over the mouth should be 
used. This will almost completely arrest particles and germs. 
This arrangement is particularly useful in the sick-room where 
contagious disease exists.1 
4. Danger of Draughts. — While it is important to secure fresh 
and pure air, in our efforts to do so we frequently subject our- 
selves to greater dangers. When the body is heated by exercise 
and weakened by fatigue, and we remain quiet in a place where 
a strong current of cold or cool air exists, we take great risk of 
“ catching cold.” A “ cold ” is a condition of the mucous mem- 
branes caused by a sudden or great lowering of the temperature 
1 Modern physicians and surgeons have gained great control over diseases by 
what is known as antiseptic treatment. In all operations of the surgeon every 
precaution is now taken to prevent germs entering the system through wounds 
and openings, and to destroy those which may already have come in contact 
with a denuded surface. The hands of the surgeon and assistants, all the instru- 
ments, bandages, and appliances are treated with certain chemicals which are 
known to destroy bacteria. In typhoid fever, consumption, diphtheria, scarlet 
fever, and other diseases due to germs the physician takes every precaution to 
destroy and prevent the spreading of these germs, and the result is that these 
diseases have lost much of their fearful nature. Babies fed upon artificial food, 
under the skillful physician’s care, now have their food sterilized, that is, sub- 
jected to a certain degree of heat for a certain time until all germs are destroyed. HYGIENE OF RESPIRATORY SYSTEM. 
of the body. It usually affects the mucous membrane of the 
respiratory passages, but it may in many cases affect the alimen- 
tary canal, so that various disturbances of the digestive function 
will result. Diarrhea and dysentery are frequently brought on 
by being exposed to draughts. One is scarcely liable to take cold 
when exercising in a draught, because the exercise keeps up the 
body temperature, but when at rest there is danger, more espe- 
cially if the person be of delicate organization and accustomed 
to an indoor life. Long exposure to severe cold and to cold 
winds frequently causes severe colds and internal inflammations. 
We do not always take cold even under the same external cir- 
cumstances, because the system has greater power of resistance 
at some times than at others. It is not well to take risks of 
this kind. Rooms should be so ventilated that while a constant 
supply of fresh air is secured, no draughts will strike the 
inmates. 
5. Proper and Improper Ventilation. — The common method of 
ventilating a room is by opening windows at top or bottom, or 
at both places. This in many cases exposes one or more of the 
inmates to dangerous draughts. In very warm weather it 
matters little, as a draught is not liable to be dangerous ; but 
when the temperature is higher inside than outside of the room, 
it is risking too much to sit still near an open window or door. 
Air that has just been breathed, and air of a room sustaining a 
fire, is warmer and consequently lighter than the air outside, 
and when a window is opened at only one place, a double cur- 
rent is established — one of cold air coming in, and one of warm 
air going out; the colder one always being below. If a window 
is opened at both top and bottom the cold current flows in at 
the lower opening, and the warm one out at the upper opening. 
Where there is no other way to ventilate than by opening 
windows, a good plan is to fix a board to the upper sash so 
inclined that the air-current is directed against the ceiling, and 
thus spread out through the room. Another good plan is to fix 
a strip of board to the window-sill so that the lower sash will 
not come quite all the way down. Then a space will be left 
between the upper and lower sash opening upwards and not 
directly towards the inmates. 128 
LESSONS IN PHYSIOLOGY. 
In a properly ventilated room there should always be an 
opening for fresh air near the stove or other source of heat, and 
another opening for the exit of foul air at a point farthest from 
the source of heat. Then the cold air enters, becomes warmed, 
and circulates through the room, while the foul air is by it 
forced out. 
This is an important subject. Statistics show that fully one- 
fourtli of all the deaths in the United States are from consump- 
tion, and a very large per cent of the rest from pneumonia and 
other diseases of the respiratory passages. These diseases are 
generally due, it is true, to specific germs, which in most cases 
cannot be prevented from entering the system; but those with 
vigorous constitutions are able to resist the encroaches of the 
germs, while those whose organs have been weakened by colds 
and other troubles brought on by draughts and foul air, are the 
ones who succumb to the deadly germs. 
6. Air of Sick-rooms. — Nowhere is proper ventilation more 
important than where persons are lying sick. Every effort 
should be made to secure a constant change of air without 
exposure to draughts. Much may be done in the way of re- 
moving gaseous impurities in the air of sick-rooms by keeping 
vessels of water standing open. The water absorbs the gases to 
a considerable extent. The water should be changed every few 
hours. 
7. Exercise and Respiration. — Judicious exercise, especially of 
the muscles of the chest and arms, is greatly beneficial to the 
respiratory organs. Young persons should take frequent drills 
in arm movements, raising and lowering the shoulders, at the 
same time standing erect with the shoulders well drawn back. 
Those occupations which bring into use the muscles of the 
chest, without overworking them, are conducive to a healthy 
respiratory system. Many a man hastens to his death from 
consumption by an indoor life and want of judicious exercise. 
Walking is a good exercise for the digestive system and the 
circulation ; but for the better development of the respiratory 
organs, more exercise of the muscles of the upper part of the 
body is needed. HYGIENE OF RESPIRATORY SYSTEM. 
129 
Breathing exercises, if carefully carried on, are excellent. 
Stand erect, throw the shoulders well back, and slowly inhale ; 
then slowly exhale. Repeat this several times in succession. 
Do this every day in the open air. Always inhale through the 
nose ; never through the mouth. Observe this at all times. The 
nasal passages modify the temperature of the air and catch a 
great deal of the dust which otherwise would pass into the 
trachea and lungs. Keep the mouth closed except when eating 
or talking. 
8. Effects of Alcohol on Respiration. — Alcohol causes at first 
an increased warmth on the surface of the body, because the 
capillaries are dilated and more blood flows to the surface. 
This is true of the lungs also. In fact the lungs and mucous 
membranes are simply arrangements to secure a vast amount of 
internal surface accessible to air. Inspiration is at first in- 
creased also. But soon a reaction occurs. The surfaces lose 
heat by radiation and evaporation, and the respiratory apparatus 
fails to keep up its usual work, and general depression follows. 
Frequent repetition of this causes in time permanent enlarge- 
ment of the capillaries of skin and lungs. Respiration cannot 
be perfect when the capillaries of the lungs are engorged, as the 
air-space is correspondingly diminished. 
Inebriates frequently succumb to lung diseases, but it is often 
indirectly due to their carelessness in protecting themselves 
from cold and dampness, the alcohol blunting their sensitive 
nerves. 
9. Effects of Tobacco on Respiration. — Tobacco exerts no direct 
effect on the respiratory organs, except in some cases it produces 
much irritation of the mucous membranes. But by its effect on 
the nervous system, digestion, and circulation, it indirectly af- 
fects the respiration and is especially injurious to young and 
nervous persons. 
EXERCISES FOR REVIEW. 
1. What is oxygen? State the composition of pure air. What effect has 
nitrogen in respiration? Carbon dioxide? Ammonia? 
2. If a solid body were dropped into the trachea, which one of the bronchi 
would it enter? 130 
LESSONS IN PHYSIOLOGY. 
3. What is the use of the cartilaginous rings of the trachea? 
4. What is the use of the epiglottis? Describe the vocal cords. What change 
in tone would be produced by increasing the tension of the vocal cords? What 
would be the effect of enlarging the rima glottidis? 
5. What is the pleura? What organ or part of the circulatory system is 
similar in structure and function to the pleura? 
6. Comparing the respiratory apparatus to a pair of bellows, what is analo- 
gous to the valve of the bellows? What causes the air to enter the lungs? 
7. What has the air lost by respiration? What gained? 
8. How many times do you breathe in a minute? What is reserve air? 
9. What relation have bacteria to the respiratory system? 
10. Why is a draught injurious? What is meant by “ taking cold ”? 
11. What are cilia? 
12. Where do we find mucous membranes? 
13. Why should we not breathe through the mouth? 
14. How may we strengthen and deepen the voice ? By forming the habit 
of full and deep breathing. 
15. How may we acquire flexibility, grace, and melody in utterance ? By 
constant practice upon suitable exercises under the criticism of a master of vocal 
expression. CHAPTER IV. 
WASTE AND REPAIR OF THE BODY, OR THE SECRETORY 
SYSTEM. 
LESSON 25. 
The Skin. 
1. The skin is that layer of tissue which covers all parts of 
the body exposed to the air, except that which is covered with 
mucous membrane. It is a very important part of the body in 
many ways. It not only protects the deeper parts and gives 
beauty to the individual, but with its appendages it is an im- 
portant secreting and excreting organ. It is like an elastic and 
tight-fitting garment which is easily kept clean and renews itself 
as fast as it wears out. It consists of two principal layers: 
(a) the epidermis, cuticle, or scarf skin; (&) and the cutis vera, 
or true skin. 
2. The Epidermis. — This is the external layer, and is composed 
of what is called horny tissue, entirely destitute of blood-vessels 
and nerves. It consists of two layers, the outer, of hard, flat- 
tened, nearly transparent cells which are continually coming off 
in the form of minute scales. These scales on the scalp consti- 
tute the so-called “ dandruffThe deep layer consists of cells 
more or less rounded and softer than those of the outer layer. 
They contain a pigment, or coloring matter, which gives the dif- 
ferent races of men their peculiar color and complexion. These 
cells become flattened and elevated and replace those of the 
outer layer, which are constantly coming off. 
The epidermis is an important part of the skin, as it affords 
protection from irritating objects, prevents the too rapid escape LESSONS IN PHYSIOLOGY. 
of heat, and limits the amount of evaporation of water. Were 
it removed from the entire body we would suffer acutely from 
the irritating effects of the air, from the cold, and from contact 
with objects. Indeed, the irritation produced by the air alone, 
if the entire epidermis were removed, would probably be so 
great as to cause nervous collapse and death. A blister is sim- 
ply a portion of the epidermis raised by the accumulation of serum 
under it. This outpouring of serum may be produced by heat, 
by pressure, and by certain chemicals. 
Fig. 18. — Vertical Section of the Skin. 
3. The Derma, or True Skin. — This is also composed of two 
layers: (a) the superficial, or papillary; and (6) the deep layer, 
or corium. The papillary layer is composed of numerous coni- 
cal projections which in the palm of the hand appear in rows, 
forming those peculiar little ridges we see. These projections, 
or papillae, are extremely sensitive and vascular, containing ter- 
minations of nerves and capillaries. The corium, or deep layer, 
is dense, tough, and elastic, and consists mainly of bundles of 
white fibrous tissue and some yellow elastic fibers and muscular 
fibers, so arranged as to form spaces called areolce. These THE SKIN. 
133 
spaces contain fat, hair-follicles, and the glands of the skin. 
The corium of the skin of animals, when thickened and hardened 
by chemicals, constitutes leather. 
4. Muscles of the Skin. — If the surface of the body be sud- 
denly exposed to cold air the skin raises in little lumps, produc- 
ing what is familiarly known as “ gooseflesh.” This is caused by 
the contraction of tiny muscles which run in a slanting direction 
through the corium. They cause, to a slight extent in man, 
the hair to “ stand on end.” In the skin of the back of a dog 
and the tail of a cat, they are capable of making the hairs 
to stand almost at right angles with the surface. These 
muscles also aid probably in throwing out the oil from the 
sebaceous glands. 
5. Peculiarities of the Skin. — The skin varies in thickness in 
different parts of the body, and slightly in different individuals. 
On the nose and some other parts it is not much more than one- 
sixteenth of an inch, while on the sole of the foot it is fre- 
quently a half inch or more. The increased thickness on parts 
that receive pressure and friction is mainly due to a thickening 
of the epidermis. The pigment, or coloring matter, of the skin, 
hair, and eyes is entirely absent in some rare cases. Such indi- 
viduals are called albinos. This peculiarity is more frequent 
among the dark races and in hot climates. The Caucasian race 
is called the white race, but they are really the red or ruddy 
race, as the small amount of pigment in the epidermis permits 
the color of the blood to show through the nearly transparent 
epidermis and walls of the capillaries. Freckles are collections of 
pigment matter in spots or masses. 
The skin is connected to the rest of the body by thin layers 
of fibrous tissue, between which lie the superficial veins and 
nerves and a variable amount of adipose (fatty) tissue. 
6. Uses of the Skin, — 1.* The insensible epidermis mechani- 
cally protects the true skin from the air and external objects, 
yet does not prevent the necessary escape of waste material. 
2. The cutis vera furnishes a bed for the numerous glands 
which will be described in a succeeding lesson, and affords a 
support to the numerous capillaries which are necessary to sup- 134 
LESSONS IN PHYSIOLOGY. 
ply blood to these glands. It also serves in a great measure to 
protect the superficial veins and nerves and the muscles beneath 
it. 3. The skin as a whole prevents the rapid radiation of heat 
from the body. This is aided by the adipose tissue beneath, 
which always exists in greater or less abundance. With its 
special glands it is one of the most important secreting and ex- 
creting organs. (See the following lessons in this chapter.) 
LESSON 26. 
The Appendages of the Skin. 
1. The hair and nails, and the sweat and oil-glands of the 
skin, may be conveniently described as appendages, although in 
a certain sense they are really parts of the skin. 
2. The Nails. — The ordinary observer would not think of 
classifying the nails with the skin, for at a glance they seem 
totally different. But microscopic and chemical investigations 
show that they are composed of modified epidermal cells. A 
nail has a root, body, and free edge. The root is covered by a fold 
of the skin, and the body is firmly attached to the matrix, as the 
tissue beneath is called. The nail has two layers, a hard, horny, 
insensible layer above, and a softer, or mucous layer beneath. 
The nail grows by a continual accession of new cells beneath 
and at the extremity of the root. The horny layer is thus 
pushed upward and forward, and worn off or cut off. Nails will 
grow several inches in length if not cut and care is taken to 
prevent undue wear and breakage. If a nail is pulled out it 
will be renewed if the root and matrix be not injured. The 
entire nail is removed by wear and cutting, and renewed by 
growth about every four or five months. 
The uses of the nails are obvious enough. The ends of the 
fingers are protected, and we are enabled to pick up small ob- 
jects with greater facility and to grasp more firmly. 
3. The Hair, — The hair, like the nails, consists of modified THE APPENDAGES OF THE SKIN. 
135 
epidermal tissu®. Each hair has a shaft, or stem, a root, and a 
point. The point of a hair which has not been cut is tapering 
and ragged. The shaft is a slightly flattened cylinder. The 
outer portion, or cortex, is composed of cells overlapping each 
other like shingles on a roof, the free ends towards the point of 
the hair. Beneath the cortex is the fibrous portion consisting 
of long cells containing the pigment, which gives hair its charac- 
teristic color. When the hair turns gray, the pigment disap- 
pears and air takes its place. In the centre is the medulla, or 
pith, consisting of irregular cells and air-spaces. The root of 
the hair is slightly enlarged, and is enclosed in a little bag 
called the hair-follicle. In the bottom of this follicle is a point 
or germ from which a new hair grows when one is pulled out. 
The hair-follicle is usually in the corium, but in large hairs it 
extends beneath it. To stop the growth of hair, the germ at 
the bottom of the follicle must be destroyed. This is no easy 
matter. 
4. Peculiarities of the Hair. — The hair grows by additions to 
the root end. When not cut, hair reaches a certain length 
(varying in individuals and races), and then grows no faster 
than will make up for the wear at the point. There are some 
cases of extremely longhair, especially on the heads of women. 
One woman’s hair measured six feet two inches. Men’s beards 
attain great length in some cases. Almost every square inch 
of surface of the skin is covered with short, thin hair. This 
has been known in a few cases to attain a remarkable length 
over almost the entire body. 
The immediate cause of hair turning gray is the absorption of 
the pigment matter and its replacement by air. Why this 
should take place in some at an early age, and in others not 
until old age, is not easily explained. Neither can we explain 
baldness, nor those rare cases where the hair turns gray from 
great grief or sudden fright in a few hours. 
Hair is very durable. That found on Egyptian mummies has 
remained unchanged through thousands of years. It is elastic, 
and may be stretched one-third of its length without breaking. 
It absorbs moisture readily, and is thereby lengthened consider- 
ably. 136 
LESSONS IN PHYSIOLOGY. 
5. Uses of the Hair. — The principal use of the hair is for 
protection from heat and cold. Being a non-conductor of heat, 
it keeps in the heat of the body, and keeps out external heat. 
It also serves as a protection to some degree from blows and 
pressure. On the body the hair helps to drain off the sweat. 
A heavy beard protects the throat and face from cold winds, 
and a thick mustache serves to arrest dust that might be inhaled 
and modifies slightly the cold of the air before it enters the air- 
passages. 
6. The Sweat-glands. — The sudoriparous, or sweat-glands, 
consist of very fine tubes beginning with a coil in the tissue 
just beneath the corium, passing in a spiral or wavy course 
through the skin, and terminate on the surface in the pores. 
They are found in nearly every part of the skin, their total 
number being estimated at 2,400,000. They are abundantly 
supplied with blood-vessels and nerves, and are important ex- 
cretory organs, being the main outlets for the superfluous water 
of the system, the water carrying in solution certain waste 
materials. (See Lesson 28.) 
7. The Oil-glands. — The sebaceous, or oil-glands, are found 
over nearly the whole body, but are most abundant on the scalp 
and face. They are absent on the palms of the hands and soles 
of the feet. They consist of clusters of little rounded sacs 
situated in the corium, or just beneath it, with a duct which 
opens either on the surface or into the upper part of a hair-follicle. 
They secrete an oily substance which keeps the skin soft and 
pliable, and protects it from the irritating effects of the perspi- 
ration. It is also the natural “ hair-oil,” keeping the hair from 
becoming dry and brittle. The oil is carried by capillary at- 
traction along the entire length of the longest hairs. It also 
flows to the palmer surface of the fingers, so that if you rub 
your finger on a piece of white paper you will make a grease 
spot more or less distinct. The sebaceous glands on the nose 
and cheeks sometimes are quite large, and opening on the sur- 
face they gather dust and smoke, and have the appearance of 
little black dots. By pressure a mass of sebaceous matter may 
be squeezed out. This mass is supposed by some to be a worm MUCOUS AND SEROUS MEMBRANES. 
with a black head. There are, however, sometimes parasites, 
visible only by the aid of a microscope, found in these glands. 
(See Lesson 28.) 
LESSON 27. 
Mucous and Serous Membranes. 
1. Extent of Mucous Membrane. — All free surfaces, directly or 
indirectly exposed to the air and not covered with the skin, are 
covered with mucous membrane. This membrane is much more 
extensive than one might suppose. It lines the air-passages, 
which include the nasal cavity, certain cavities in the bones of 
the face and cranium, the mouth, the pharynx, the Eustachian 
tube, the larynx, trachea, and bronchial tubes, and the air-cells 
of the lungs. It lines the entire alimentary canal, which is 
about thirty feet in length, and the ducts of all glands which 
pour their secretions into it, as the salivary ducts, the ducts of 
the liver and pancreas. Also the kidneys and their ducts and 
the bladder. To sum up, it lines all cav- 
ities and passages which have external 
openings direct or indirect. 
2. Structure. — Mucous membrane con- 
sists of one or more layers of cells, some- 
times called epithelium, arranged on a 
fibrous tissue. The cells of the different 
layers differ in shape and size. The 
cells of the outer layer show a tendency 
to come off, and their places are taken 
by cells from the layers beneath, these cells becoming changed 
in form as they approach the surface. The cells of the outer 
layer differ in different parts of the body; some are like col- 
umns, some rounded, some flattened. Columnar epithelial 
cells, with fine, hair-like projections called cilia, exist in the 
respiratory passages. The uses of these cilia were explained in 
the chapter on Respiratory System. 
Fig. 19. — Ciliated Epithe- 
lium from Trachea. 138 
LESSONS IN PHYSIOLOGY. 
The epithelium has no blood-vessels and, with some excep< 
tions, no nerves. The fibrous tissue beneath is abundantly sup- 
plied with blood-vessels and nerves. In this fibrous tissue are 
found in many places mucous glands and special glands, as 
those of the stomach and intestines. 
3. Uses of the Mucous Membrane. — The mucous membrane 
serves to protect all internal surfaces exposed to air, which is 
always an irritant to the delicate tissues of the organs of the 
body. It is continually kept moist by the secretion of mucus. 
This acts as the protective agency not only against the air, but 
against gases and solids which exist in the air as impurities. The 
membrane is easily injured by sharp or rough bodies, but heals 
again with remarkable rapidity. 
4. Extent of Serous Membranes.— All surfaces not exposed to 
the air are lined with serous membrane. Such surfaces are not 
quite so extensive as those lined with mucous membrane, but 
they are equally necessary and important. In the brain and 
spinal cord are found certain cavities. These are lined with 
serous membrane. All the organs of the thoracic cavity are 
covered with a serous membrane, which is reflected and lines 
the walls of the cavity also. That which covers the lungs and 
lines the chest walls is called the pleura. A serous membrane 
covers the heart and lines the pericardium. That which lines 
the abdominal cavity and covers all the organs within it is called 
the peritoneum. It has many divisions, which take different 
names. A serous membrane lines the blood-vessels and lym- 
phatics and the cavities of the heart. It is also found in the 
internal ear. The synovial membranes of the joints are modified 
serous membranes. 
5. Structure. — Serous membrane resembles mucous mem- 
brane somewhat in structure, consisting of layers of cells on a 
fibrous tissue. These layers of cells are sometimes called endo- 
thelium. The cells are usually flattened, and form a very 
smooth and shining surface, which is constantly moistened with 
a serous fluid. The endothelial cells contain no blood-vessels 
nor nerves, but the tissue beneath is abundantly supplied with 
them. SECRETION, EXCRETION, AND ABSORPTION. 
6. Uses of Serous Membranes. — They are mainly for the pur- 
pose of preventing friction of one part on another. The organs 
being covered with this smooth, moist membrane, and the cavi- 
ties in which they lie being lined with it, they may move freely 
without injury. This membrane when exposed to the air or to 
foreign substances is easily irritated, and dangerous inflamma- 
tions frequently follow such exposure. This explains why a 
wound through the abdominal cavity so frequently proves fatal. 
Blood, the contents of the alimentary canal, and the air, con- 
taining poisonous germs, are apt to cause peritonitis, or inflam- 
mation of the peritoneum, which is usually fatal. Surgical 
operations where it is necessary to expose this membrane were 
once attended with much risk of life, but modern surgeons take 
such precautions to preclude the entrance of germs, and to 
secure absolute cleanliness, that the risks are greatly lessened. 
7. The Real Inside of the Body. — When food or a foreign 
body passes into the stomach we are accustomed to say that it 
is in the body, but anatomically and physiologically this is not 
correct. It is on the outside anatomically because the mucous 
membrane is continuous with the skin, which is the external 
covering. It is on the outside physiologically because the food 
must pass through the mucous membrane before it can be assim- 
ilated with the tissues of the body. There are some animals 
low in the scale which are in the form of a bag or flexible cylin- 
der. They may be turned completely inside out and apparently 
suffer no inconvenience; the external covering becomes a digest- 
ing and absorbing surface, as the internal was before. This 
shows the close relation between the skin and the mucous 
membrane. 
LESSON 28. 
Secretion, Excretion, and. Absorption. 
1. Secretion and Excretion defined. — These terms are some- 
times confusing to the student. The following, adapted from 140 
LESSONS IN PHYSIOLOGY. 
Foster, explains their proper use: “ The protoplasm (see Intro- 
duction) is continually undergoing chemical change (metabo- 
lism), room being made for the new protoplasm by the breaking 
up of the old protoplasm into products which are cast out of 
the body and got rid of. These products of metabolic action 
have, in many cases at all events, subsidiary uses. Some of 
them, for instance, we have reason to think, are of value for the 
purpose of dissolving and effecting other preliminary changes 
in the food introduced into the body; and hence are retained 
within the body for some little time. Such products are gen- 
erally spoken of as secretions. Others, which pass more rapidly 
away, are generally called excretions. The distinction between 
the two is an unimportant and frequently an accidental one.” 
Some of these secretions, as saliva, gastric juice, bile, etc., 
have been discussed with the Digestive System. 
2. Perspiration. — A large amount of the superfluous water 
of the system is disposed of through the skin in the form of 
perspiration. We are constantly perspiring, but so long as the 
perspiration evaporates as fast as it is produced we do not per- 
ceive it and call it insensible perspiration. Whenever it be- 
comes so abundant as to collect in drops and appear as moisture 
we speak of it as sensible perspiration. The proportion of sen- 
sible and insensible perspiration varies Avith the amount of 
secretion and with the dryness and motion of the atmosphere. 
When the air is dry and in motion the evaporation is much 
more rapid and less appears as sensible perspiration. As the 
evaporation of the perspiration cools the body, this explains 
why our sensations are not a true index of the temperature of 
the atmosphere. When the air is dry and in motion we can 
endure a very high temperature, because evaporation is rapid 
and the body is parting Avith its heat at a corresponding rate. 
On the other hand, Avhen the air is saturated Avith moisture and 
no breeze is blowing, we feel very Avarm, because the heat is 
retained in the body. 
The total amount of perspiration varies with the fluids taken, 
nature of the food, temperature, amount of exercise, mental 
condition, and with the amount of secretion by other organs, SECRETION, EXCRETION, AND ABSORPTION. 
141 
especially the kidneys. The amount of perspiration is greatly 
increased in certain diseased conditions, and is affected by cer- 
tain medicines. 
3. Uses of Perspiration. — Besides carrying out a large amount 
of waste material, the perspiration is the main heat-regulating 
agency of the body. As stated in another place, the tempera- 
ture of the body varies but little under all circumstances. The 
heat is constantly being produced by the combustion of the 
tissues, and the surplus is constantly being expended largely in 
evaporation of the perspiration. Some heat is lost by direct 
radiation, and some by warming the other excretions, and a con- 
siderable amount by warming the expired air. A cup of hot 
tea in warm weather, paradoxical as it may seem, is a cooling 
agent, since it induces copious perspiration, which cools the 
body by its evaporation. 
4. The Kidneys. — The kidneys are two excreting glands sit- 
uated in the “ small of the back,” behind the intestines. They 
are about four inches long, two inches wide, and one inch thick, 
and of the shape of a bean. They consist mainly of a series of 
minute tubes intermingled with blood-vessels. The secretion 
is carried to the bladder by two tubes, or ducts, called ureters. 
The use of the kidneys is to remove from the blood certain 
salts, and a poisonous, organic waste substance called urea. If 
in any way their action is interrupted, the blood becomes 
poisoned b}r the accumulation of urea and other waste matter, 
and serious or fatal results follow. 
5. Absorption from Surfaces. — It is a well-known experience 
that bathing quenches thirst, and the body will gain in weight 
after immersion for some time in water. Medicines, such as 
liniments, are absorbed when rubbed on the skin. A quantity 
of mercury sufficient to produce salivation may be introduced 
into the system by simply rubbing it on the surface. A drop of 
prussic acid, if placed on the tongue of an animal, will produce 
death in a few minutes. The poison is evidently absorbed from 
the mucous membrane. If the epidermis be removed, absorp- 
tion from the surface is very rapid. The digested food enters 
the system through the mucous membrane of the alimentary 142 
LESSONS IN PHYSIOLOGY. 
canal by absorption, passing directly into the blood-vessels, or 
indirectly by way of the lacteals. 
6. Internal Absorption. — If a frog be taken in the latter part 
of the “ tadpole ” stage and kept in water, in a few days its 
comparatively large tail will gradually disappear, the body 
increase in size, and legs appear, although not a particle of 
food be given it. What has furnished material for the growth 
of body and legs ? Evidently the material of the tail has been 
absorbed and carried by the circulatory system, and built up 
into the tissues of the body and limbs. The agents of absorp- 
tion here are probably the lymphatics. In like manner young 
snakes increase in length for some days after leaving the egg, 
the nourishing material being a portion of the yelk retained in 
the body of the young snake. Tumors and abnormal growths 
often disappear of themselves, the material being absorbed and 
carried out doubtless as waste matter. 
7. Waste and Repair. — All the secreting and excreting glands 
and surfaces of the body are connected more or less directly 
with the processes of waste and repair which are constantly 
going on, and really constitute the life of the body. A dead 
animal does not secrete nor excrete. In other words, there is 
no vital activity in the cells of a dead body. The only activity 
is that of chemical change, which sooner or later results in the 
complete destruction of the body. The secretory system is 
intimately blended with all other systems engaged in the nour- 
ishment of the body, that is, in nutrition. Various glands fur- 
nish fluids which dissolve and prepare the food for absorption 
and assimilation. Other glands separate from the blood certain 
material thrown into it by the tearing down of old tissue, thus 
getting rid of material which has served its purpose. The res- 
piratory organs take in oxygen, which is intimately connected 
with the manufacture of various secretions and the destruction 
of old tissues. 
PRACTICAL ILLUSTRATIONS. 
1. With a sharp knife scrape the skin of the arm or hack of the hand. A 
white powder appears. Under the microscope this is seen to consist of flattened 
epidermal cells. The ordinary contact with clothes and objects keeps the loose 
cells rubbed off. HYGIENE OF THE SECIiETOKY SYSTEM. 
143 
2. Take a hair from your head and roll it between thumb and finger, back 
and forth. Observe that it tends to move at the same time lengthwise, and 
always in the direction of the root of the hair. The reason of this may be seen 
if a hair is highly magnified. The cells of the outer part overlap and project 
like shingles. 
3. The experiment (mentioned in the text) of keeping a tadpole until it 
becomes a frog may be tried. Select the largest specimen you can find. Keep 
it in a dish of water in the schoolroom and permit the pupils to watch the changes 
from day to day. 
4. The experiment with the egg to illustrate absorption, given in the chapter 
on Digestive System, may be repeated at this stage, or at least attention should 
be called to it. 
LESSON 29. 
Hygiene of the Secretory System. 
1. Cleanliness. — The excretions of the body act as poisons if 
again introduced into the system. The skin may absorb any 
soluble substance which remains for any length of time in con- 
tact with its surface. Thus the excretions may prove a source 
of danger. Again, if excreted material is permitted to remain 
long on the skin, it, together with the dust and dirt, partially 
closes the pores and retards the necessary excretion which 
should be kept up at all times. A dirty skin is also frequently 
the breeding-place for germs of skin diseases. It is a fact, at 
least, that the greatest variety and most numerous cases of trou- 
blesome skin diseases are found among those who are habitually 
filthy in their persons. These are sufficient reasons for keeping 
the surface of the body clean. 
2. Value of Bathing. — We should bathe the entire body at 
least as often as once a week for cleanliness’ sake. No matter 
what the occupation and surroundings may be, the skin in that 
time will have accumulated an amount of excreted matter and 
foreign dirt which will be injurious if allowed to remain. In 
warm weather, when the perspiration is more abundant, it is 
necessary to bathe oftener. Occupations which expose the body 
to dust and dirt necessitate frequent bathing. Bathing, when 144 
LESSONS IN PHYSIOLOGY. 
properly done, has often beneficial results, even when not neces- 
sary for cleanliness. It is a means of getting rid of surplus heat, 
and by exciting the skin to increased action often relieves con- 
gestion of internal organs. A bad cold may often be cured by 
taking a warm bath on going to bed. However, if one does not 
keep warm during the night, or is exposed the following day, a 
more severe cold may be taken. 
3. Methods of Bathing. — It is not necessary to immerse the 
body in water in order to get the full benefit of a bath. A gal- 
lon of water in a basin, a sponge or soft cloth, a piece of soap, 
and a towel are all that are essential. A bath tub, a bathing 
tank, or a body of water is a luxury rather than a necessity. A 
thorough drying of the skin by vigorous rubbing with a towel 
is important in cold weather, as the dampness imparted to the 
clothes may cause chilliness afterward. Besides, the friction 
arouses the activity of the blood-vessels, and a thorough circula- 
tion near the surface is thus secured and the body fortified 
against external cold. 
4. Kinds of Baths. — We read of warm, hot, cold, and luke- 
warm baths; of salt water baths, of vapor baths, and even of 
sun and air baths, and all have their particular value in certain 
cases. For the purpose of cleanliness for which baths should be 
most frequently taken, the water should be at a temperature 
agreeable to the sensations. A hot water bath is stimulating 
to the skin, as also is a vapor bath. They are always followed 
by a feeling of lassitude or depression, and a good rest should 
follow such a bath. A cold bath is frequently dangerous, es- 
pecially to the young and delicate, and to the aged. It gives a 
shock to the nervous system and drives the blood from the sur- 
face to the internal organs, and unless the skin be quickly dried 
and thoroughly rubbed to get up a reaction, the results are 
more injurious than beneficial. A cold bath is said to be tonic, 
or strengthening to the system, and persons in vigorous health 
soon get used to cold water and quickly recover from the tem- 
porary shock. But why should healthy and vigorous persons 
need a tonic ? In our opinion, a cold bath is rarely, if ever, a 
necessity, and since it is so frequently attended with risks, we HYGIENE OF THE SECRETORY SYSTEM. 
145 
cannot advise it as a hygienic measure. A luke-warm bath in 
hot weather is cooling and refreshing, the evaporation of the 
moisture being attended with abstraction of heat. As to salt 
water baths and medicated baths generally, they are best taken 
under the advice of a physician. 
5. Too much bathing may be injurious. The skin is over- 
excited, and consequently overworked. Boils and other erup- 
tions often result from excessive use of the bath. Two or three 
times a week is generally often enough to bathe the entire body 
under any circumstances. One should not remain too long in 
water during a bath. Ten or fifteen minutes should be the 
limit. 
6. Clothing. — The warmest clothing is that which is the 
poorest conductor of heat, for then the heat of the body is kept 
in. Fur, wool, and feathers are the poorest conductors of heat; 
silk is next, and cotton next, linen being the best conductor. 
Clothes tend to keep an even temperature about the surface of 
the body. They keep in the body heat, and keep out the heat 
of the sun when we are in its direct rays. Clothing should be 
adapted to the season of the year and the climate. It is not 
wise in our changeable climate to leave off our winter under- 
clothing too early in the spring. It is better to endure the 
increased heat for a few days, than to take the risk of getting 
chilled, and thus taking a cold when a sudden change occurs. 
Wet or damp clothes should never be worn for a minute, when 
it is possible to change them for dry ones. If compelled to 
wear damp clothes for a time, one should keep exercising. 
Rheumatism, neuralgia, throat and lung diseases, and even 
diseases of the digestive organs, are frequently caused by 
neglect in the matter of clothing. For the sake of cleanliness, 
the underclothing should be frequently changed. It is wise to 
wear one garment at night and another in the daytime. The 
one that is not worn should be hung up to air. Bed-clothes 
should be aired during the day. 
7. Use of Cosmetics. — If a person has not naturally a beautiful 
complexion, all the cosmetics in the world cannot make it 
beautiful. The lady who keeps her complexion on her toilet- 146 
LESSONS IN PHYSIOLOGY. 
table, and puts it on when she goes out into society, may deceive 
those at a distance, like the actress on the stage; but she must 
be skillful indeed who can imitate the bloom and beauty of a 
healthy skin. But no objection could be made to the use of 
cosmetics if they were not injurious. They generally contain 
poisonous substances which may be absorbed. Besides a con- 
stant use of the mildest face powders and paints destroys the 
beauty of the skin by clogging up the pores and interfering 
with its normal action. A free use of soft water and a mild 
soap, with attention to the general rules of health, Avill produce 
a beautiful complexion if such be possible. 
8. Care of Hair and Hails. — It adds much to the comfort and 
health of the body to keep the hair well combed and brushed. 
An occasional “ shampoo ” with warm, soft water and some 
mild soap is good. Do not use oil on the hair unless it be 
unnaturally dry and harsh. All hair-dyes tend to destroy the 
natural softness and flexibility of the hair. The upper surface 
of the nails should be cleaned with a brush and not scraped 
with a knife, if you would preserve the natural polish. 
9. Handling Poisons. — As we have learned elsewhere, absorp- 
tion from the surface is very rapid where the epidermis has 
been broken or removed. Physicians and medical students 
have been seriously poisoned in dissecting human bodies; a 
peculiar poison, developed by the chemical changes in the decay 
of a body, being absorbed through abrasions on the hands or 
where a slight wound was made by the dissecting knife. Cer- 
tain diseases are communicated in a similar manner. Great 
care should be exercised in handling poisonous substances, as a 
quantity sufficient to prove serious, if not fatal, may be ab- 
sorbed. 
10. Chafing- and Chapping of the Skin. — Where the skin is fre- 
quently exposed to cold winds, or to water and other liquids, it is 
apt to crack, and where there is friction and moisture it is apt to 
chafe and become very irritable. The proper remedy is a sub- 
stance which will not irritate in itself, but will form an air-tight 
covering, as the air is the great irritant to a denuded surface. 
Linseed oil is such a remedy. It may be used in a liquid form, HYGIENE OF THE SECRETORY SYSTEM. 
147 
or mixed with melted paraffine, or spermaceti, and made into an 
ointment. This is excellent for burned and scalded surfaces 
also. 
11. Effects of Alcohol on the Secretory System. — Alcohol has a 
marked effect on all glands. We have already mentioned its 
effects on the liver. The kidneys are especially stimulated by 
alcohol, and in time become diseased in consequence of the 
overwork. Many men die at about the age of fifty from kidney 
disease, and in a large percentage of cases these men have been 
habitual drinkers. The perspiratory glands are overworked, 
and the body loses heat more rapidly than is natural. The 
effect of alcohol on the skin is apparently contradictory. A 
man feels a glow of warmth as the result of a dram or two, 
and it is a common notion that it warms the body; yet the expe- 
rience of those who have tried to brave an Arctic climate is, 
that only those who abstain from alcoholic drinks can endure 
the intense cold. This is easily explained when we consider 
the philosophy of its action. Alcohol increases the force and 
frequency of the heart and dilates the small blood-vessels; 
hence the warm blood of the interior is rapidly sent to the sur- 
face, and there the heat is lost by radiation and by evaporation 
of the perspiration, which is also increased by the flow of blood to 
the sudoriparous glands. The general temperature of the body 
is thus lowered, while the heat on the surface is temporarily 
increased. Thus if a man is expected to remain in a very cold 
atmosphere for a very short time, the alcohol would help him 
endure the cold, but after a few hours his condition would be 
worse than if he had abstained. 
12. Corns and Bunions are peculiar thickened indurations of 
the epidermis, caused by pressure from shoes that are too tight, 
or rubbing of shoes that are too loose. The only sure remedy is to 
cut them out with a sharp knife, and avoid pressure on the parts 
until the normal condition is restored. Even then it is some- 
times difficult to get rid of them. The better way is to wear 
shoes that fit perfectly, and thus avoid the cause. 148 
LESSONS IN PHYSIOLOGY. 
EXERCISES FOR REVIEW. 
1. What are the relations of the skin and mucous membrane? What is the 
true interior of the body? 
2. Uses of serous membrane? of mucous membrane? 
3. Epithelium? Endothelium? Cilia? 
4. Define secretion and excretion. 
5. Uses of perspiration? When is perspiration most copious? Sensible and 
insensible perspiration? 
6. Compare section 3, Lesson 28, with section 4, Lesson 24. 
7. Of what use are the muscles of the skin? What is the cause of “goose- 
flesh ”? 
8. Use of the oil-glands? Where most numerous? 
9. Why bathe? Why keep the body clean? 
10. When is the proper time to bathe? If for cleanliness, any time that is 
convenient; if for any other purpose, advise with a reliable physician. 
11. When should we use cosmetics for the complexion? 
12. What is the physiological reason for wearing clothes? 
13. The temperature being the same, why do we feel warmer in a moist than 
in a dry atmosphere? 
14. Compare section 2, Lesson 27, with section 5, Lesson 22. 
15. What is an albino? 
16. What causes the “ hair to stand on end ”? 
17. Explain the disappearance of the tadpole’s tail. 
18. How is the heat of the body regulated? 
19. From which end does a hair grow? Part III. 
HOW THE BODY IS UOVERNED, OR THE SENSORY 
APPARATUS. 
CHAPTER I. 
HOW ALL PARTS COMMUNICATE WITH ONE ANOTHER, OR THE 
NERVOUS SYSTEM. 
LESSON 30. 
The Brain and Spinal Cord. 
1. The nervous system may be conveniently divided into 
(«) the encephalo-spinal system and (6) the sympathetic, or 
ganglionic system. The encephalo-spinal system consists of 
the brain, spinal cord, and nerves branching from them. The 
sympathetic system consists of a double chain of nerve-knots, 
or ganglia, which are connected with each other and with the 
nerves of the encephalo-spinal system by a net-work of nerves. 
2. Size of the Brain. — The brain is a large mass of nerve- 
matter completely filling the cranial cavity. In the Caucasian 
race, the brain averages about ninety cubic inches in bulk. 
Daniel Webster’s brain measured 122 cubic inches. The 
average weight in males is 49i oz.; in females, 44 oz. The 
prevailing weights in males are 46 to 53 oz.; in females, 41 to 
47 oz. The greatest weight out of 278 cases of males was 65 oz., 
and the smallest, 34 oz. In females out of 191 cases the great- 
est weight was 56 oz. and the smallest, 31 oz. The brain of 
Cuvier, the great French naturalist, weighed 64 oz. Dr. Aber- 150 
LESSONS IN PHYSIOLOGY. 
crombie’s brain weighed 63 oz. The brains of idiots seldom 
weigh over 23 oz. One specimen weighed only oz., the small- 
est on record. The human brain is absolutely heavier than 
that of any animal except the elephant and the whale, and 
relatively to the weight of the body it is heavier than that of 
most animals. 
3. Coverings of the Brain. — The brain has three distinct, 
membranous coverings or envelopes: (1) the dura mater (hard 
mother), or outer covering, is a dense, inelastic, fibrous mem- 
brane which answers also as an internal periosteum to the 
bones of the cranium. It dips into the large fissures which 
separate the different parts of the brain, and is continued on 
the cranial nerves to the outside of the cranium. (2) The 
arachnoid (spider-web like) is the middle covering. It is a thin, 
delicate, transparent serous membrane. There is a space be- 
tween it and the dura mater filled with a serous fluid, also a 
space between it and the pia mater, which also contains a serous 
fluid. (3) The pia mater (soft mother) consists of a net-work 
of minute blood-vessels held together by fibrous tissue. It dips 
into all the furrows on the surface of the brain, and lies per- 
fectly close to the brain substance. These membranes are for 
the threefold purpose of nourishing the bones of the cranium, 
protecting the brain from injury, and nourishing the substance 
of the brain. The dura mater furnishes blood to the bones and 
the pia mater to the brain, while the arachnoid, with its fluids, 
acts as a cushion to prevent shocks. 
4. Divisions of the Brain. — The brain consists of four quite 
distinct parts, very unequal in size,—the cerebrum, the cere- 
bellum, the pons Yarolii, and the medulla oblongata. Each of 
these is double, having two distinct, lateral, nearly symmetrical 
portions, united in a central line from before backward. 
5. The Cerebrum. — This is the largest part of the brain, being 
about seven times as large as the other parts taken together. 
It fills the whole of the cranial cavity above the level of the 
eyes and ears. Looking at it from above, we see a deep fissure 
running from before backward and extending entirely through 
it at the front and back, but only part way through in the THE BRAIN AND SPINAL CORD. 
151 
center, leaving a mass of matter called the corpus callosum, 
which unites the two hemispheres. The surface of each hemi- 
sphere is divided, by winding, irregular furrows about an inch 
in depth, into folds called convolutions. This greatly increases 
the amount of surface. This is significant when we learn that 
the surface of the cerebrum is gray nerve-matter and that the 
center, or source of nerve- 
power, lies in the gray 
matter. In the lower ani- 
mals these convolutions 
become less and less as we 
descend in the mental scale 
until we reach those with 
perfectly smooth cere- 
brums. A considerable dif- 
ference may be noted in 
the brains of men of intel- 
lect, as compared with 
idiots and men of the 
lower races. 
Looking at the cere- 
brum from below, as many 
as thirteen different parts 
may be seen. These have 
all been minutely de- 
scribed and named by anat- 
omists, although the special uses of all of them are not known. 
Anatomists also describe five distinct lobes or divisions of each 
hemisphere, marked off by fissures more or less prominent. 
6. The Cerebellum. — The cerebellum, sometimes called “ the 
little brain,” is about one-eighth of the size of the cerebrum, and 
lies in the lower and back part of the cranium. The surface of 
its hemispheres is marked by many curved furrows. 
7. The Pons Varolii. — This term means, “ the bridge of 
Varoli,” so named from an Italian anatomist. It seems to con- 
nect all of the other parts of the brain together, the cerebrum 
above, the cerebellum behind, and the medulla oblongata below. 
fIG- 20. — Upper Surface OF the Cerebrum 
n, Longitudinal fissure; B, The hemispheres. 152 
LESSONS IN PHYSIOLOGY. 
8. The Medulla Oblongata is a pyramidal-shaped mass connect- 
ing the spinal cord below with the pons Yarolii above. It lies 
in the lowest part of the cranium, its lowest portion on a level 
with the outer edge of the foramen magnnm, or great opening 
in the occipital hone. It is the connecting link between the 
spinal cord and the brain proper. 
9. Structure of the Brain. — The intimate structure of nerve- 
tissue will be given in Lesson 32, but it will be necessary here 
Fig. 21. — The Base of the Brain. 
to describe in a general way the interior of the mass of nerve- 
matter composing the brain. A section made horizontally 
about an inch from the top shows the upper part of the corpus 
callosum, and the interior of the hemispheres of the cerebrum. 
The gray matter is seen to form a layer about a quarter of an 
inch thick on the outside, and following the convolutions. In- 
side of the gray matter is a mass of white matter. The whole 
substance of the brain is very soft, and to make a section it is 
necessary to harden it by soaking it in alcohol or chromic acid 
for some days. A section a little lower through the corpus THE BRAIN AND SPINAL CORD. 
153 
callosum shows two large, curiously shaped cavities, the lateral 
ventricles, one in each hemisphere. They are lined with se- 
rous membrane and contain a fluid. In the septum which sepa- 
rates them is a similar small cavity called the fifth ventricle. 
A section still lower shows the third ventricle beneath the fifth. 
The fourth ventricle lies between the cerebrum, the cerebellum, 
and the pons Varolii.1 
A section of the cere- 
bellum shows white 
matter in the center 
and gray on the out- 
side, but the gray mat- 
ter dips in so deep and 
in so many places that 
the whole on section 
appears like a tree with 
many branches. This 
appearance is called 
the arbor vitce, or “ tree 
of life.” The pons 
Varolii consists of al- 
ternate layers of trans- 
verse and longitudinal 
white fibers mingled 
with gray matter. The 
upper part of the me- 
dulla is a mixture of 
white and gray matter, and the lower part is like the spinal 
cord, having gray matter in the center and white on the surface. 
10. The Spinal Cord is a continuation of the brain downward 
through the spinal canal, which is composed, as we learned in 
Fig. 22.— Horizontal Section oe Cerebrum. 
Showing the lateral ventricle and part of the corpus 
callosum, also the arrangement of gray and white 
matter. 
1 In the very center of each hemisphere of the cerebrum lie two masses of 
gray matter, the optic thalamus and the corpus striatum. Fibers of the 
white matter diverge from them to the gray matter of the cortex, or surface 
layer. These masses of gray matter, with their connection by means of fibers 
with the gray cortex, are believed to be of great importance, although their com- 
plete functions have not yet been made clear by physiologists. 154 
LESSONS IN PHYSIOLOGY. 
an earlier chapter, of a succession of openings in the vertebra. 
It extends from the foramen magnum of the occipital bone to 
the lower border of the first lumbar vertebra, about sixteen 
inches in length. It is about one-half inch in diameter, and 
weighs about one and one-half ounces. In shape it is nearly 
cylindrical, terminating in a slender filament. It is partly 
divided into two lateral portions by two fissures, and each half 
contains two bundles of fibers, called the anterior and posterior 
columns. It is covered by a continuation of the membranes 
covering the brain. The dura mater differs from that of the 
brain, in that it does not form a periosteum for the bone, but 
lies at a little distance from it, attached by fibrous bands, does 
not dip into the fissures, and contains no sinuses, or venous 
channels. The gray and white matter occupy reverse positions 
from that in the brain. The gray matter forms a mass in the 
center, which on cross-section appears somewhat in the shape of 
the letter H. At each vertebra a pair of nerves are given off. 
PRACTICAL ILLUSTRATIONS. 
1. Procure the head of some small animal, as a cat, dog, rabbit, squirrel, or 
rat. By means of a chisel and strong knife break and cut away the bones and 
take out the brain. Care and patience are necessary to get out a brain without 
injury, as it is so soft and yielding. The dura mater is easily recognized. The 
other membranes are so delicate that special preparation and care are necessary to 
demonstrate them. Put the specimen in clear water in a dish and exhibit it to 
the class. The shape, will differ somewhat from the human brain, but the gen- 
eral arrangement of parts is similar. Before attempting to make a dissection of 
the specimen, place it in alcohol and let it remain a week or longer. Then with 
a very sharp, thin knife cut sections as described in the section on ‘ ‘ Structure of 
the Brain.” It may be possible to procure a good specimen of the brain of a 
pig, sheep, or ox from the butcher, but usually the mode of slaughtering the 
animals results in destroying the structure of the brain. 
2. A section of the spinal cord may be shown in its position by sawing through 
several vertebrae. A good specimen may be obtained from the butcher. Observe 
the roots of the spinal nerves and the ganglia, to be mentioned in the following 
lesson. THE NERVES AND GANGLIA. 
155 
LESSON 31. 
The Nerves and Ganglia. 
1. The nerves proper are those white, cord-like extensions of 
the nervous system which branch to every part of the body. So 
numerous are the small branches that there is no spot on the 
surface of the body where a fine needle would not puncture one 
or more, if inserted to the depth of a quarter of an inch. There 
are no nerves in the epidermis or hair, and they are more 
numerous near the surface of the body. 
The nerves of the encephalo-spinal system may be divided 
into : (1) the cranial, or those which branch off from the brain ; 
and (2) the spinal, or those which branch from the spinal cord. 
2. The Cranial Nerves. — Some authors describe nine pairs of 
cranial nerves, others twelve pairs. The reason of this is that 
several of the nerves are common as to their origin, but separate 
as to distribution. In the subjoined table, giving the names 
origin, distribution, uses, etc., they are numbered by both sys- 
tems. They are all connected with some portion of the surface 
of the brain, and this is called their superficial origin. All have 
been traced much deeper into the brain, and the part to which 
they may be followed is called the deep origin. In the table we 
have given only the superficial origin. The exact deep origin 
of all the nerves is not yet a settled question. 
3. The Spinal Nerves. — In the region of the cervical verte- 
brae are given off from the spinal cord eight pairs of nerves, 
which are distributed to the neck and arms. They are called 
cervical nerves. In the back, passing out between the dorsal 
vertebrae, are twelve pairs called dorsal nerves. They are dis- 
tributed to the trunk. There are five lumbar nerves, five sacral 
and one coccygeal. They supply the pelvis and lower limbs. 
4. Plexuses. — The spinal nerves unite in groups and then 
branch again, forming what are called plexuses. The four 
upper cervical nerves form the cervical plexus in the neck; the 
four lower cervical and the first dorsal form the brachial plexus 156 
LESSONS IN PHYSIOLOGY. 
NUMBERS. 
NAMES. 
ORIGIN. 
EXIT FROM CRANIUM. 
DISTRIBUTION. 
FUNCTION. 
1. 
1. . 
Olfactory. 
Olfactory bulb,front- 
al lobe of cerebrum. 
Through ethmoid 
bone. 
To lining membrane of 
nose. 
Nerve of smell. 
2. 
2. 
Optic. 
Optic commissure, 
anterior part of 
cerebrum. 
Optic foramen in sphe- 
noid bone. 
To the eye, its expan- 
sion the retina. 
Nerve of sight. 
3. 
3. 
Motor oculi. 
Front of ponsVarolii. 
Through sphenoidal 
fissure. 
To all the muscles of 
the eyeball except 
two. 
Nerve of motion to 
eyeball. 
4. 
4. 
Pathethic, or troch- 
lear. 
Base of brain, front 
of pons Varolii. 
Sphenoidal fissure. 
To superior oblique 
muscle of eyeball. 
Nerve of motion to 
eyeball. 
5. 
5. 
Trifacial, or trigem- 
inus. 
By two roots, side of 
pons Varolii. 
Through sphenoidal 
bone. 
To eye, upper and 
lower jaws, face, 
and tongue. 
Nerve of taste, of 
sensation and mo- 
tion. 
6. 
6. 
Abducens. 
Near pons Varolii.. 
Sphenoidal fissure. 
To external rectus 
muscle of eyeball. 
Nerve of motion to 
eyeball. 
7.- 
' 7. 
Facial, or portio 
dura. 
Side of medulla. 
Enters with auditory 
nerve to petrous por- 
tion of temporal 
bone, leaves at stylo- 
mastoid foramen. 
To muscles of side of 
face. 
Nerve of motion to 
muscles of expres- 
sion in face. 
8. 
Auditory, or portio 
mollis. 
Side of medulla. 
Does not leave cra- 
nium. 
To internal ear. 
Nerve of hearing. 
f 0. 
Glosso-pharyngeal. 
Medulla. 
Jugular foramen. 
Tongue and pharynx. 
Sensation, motion, 
and taste. 
8.- 
10. 
Pneumogastric, or 
par vaguin. 
Medulla. 
Jugular foramen. 
Lungs, heart, and 
stomach. 
Motion and sensa- 
tion. 
11. 
Spinal accessory. 
Spinal cord. 
Enters cranium along 
with cord, and 
emerges at jugular 
foramen. 
Muscles of neck. 
Motion and sensa- 
tion. 
9. 
12. 
Hypoglossal 
Medulla. 
Anterior condyloid fo- 
ramen of occipital 
bone. 
To tongue. 
Nerve of motion to 
tongue. 
TABLE OF CRANIAL NERVES. STRUCTURE AND COMPOSITION OF NERVE-TISSUE. 
157 
near the armpit. The four upper lumbar nerves form the lumbar 
plexus in the small of the back and the last lumbar, and three 
upper sacral nerves form the sacral plexus, lying on the inner 
surface of the sacrum. 
5. Roots of the Spinal Nerves. — Each spinal nerve has two 
roots, a posterior and anterior, arising respectively from the pos- 
terior and anterior columns of the cord. The two roots unite 
in the foramen, which permits their exit from the spinal canal. 
If the anterior root be severed all power of motion is lost in that 
part to which the nerve is distributed, while sensation is not 
affected. If the posterior root only be severed, the power of 
sensation is lost, while the power of motion is not affected. 
Cutting both roots has the same effect as cutting the nerve. 
On each posterior root is a ganglion, or knot of nerve-matter. 
6. The Sympathetic System. — Two chains of ganglia, one on 
either side of the spinal column, with numerous branches and 
plexuses, constitute the sympathetic system of nerves. It seems 
to be analogous to the entire nervous system in the invertebrate 
animals which have no brain or spinal cord. The branches 
from the ganglia are of three kinds: (1) of communication be- 
tween ganglia; (2) of communication with cranial and spinal 
nerves; (3) of distribution to the various internal organs. 
There are also three great plexuses, the most important of 
which is the solar plexus in the neighborhood of the stomach 
and intestines. If a person receive a severe blow on the abdo- 
men, even though no tissue be torn or broken, death may follow 
from the shock received by these sympathetic nerves and trans- 
mitted to the brain. The solar plexus has been called the “ ab- 
dominal brains 
LESSON 32. 
Structure and Composition of Nerve-Tissue. 
1. Nerve tissue is of two general kinds, gray or vesicular 
matter, and white or fibrous matter. 158 
LESSONS IN PHYSIOLOGY. 
2. Gray Matter. — The gray matter is found in the outside or 
cortex of the brain, in certain large masses in the base of the 
brain, in the center of the spinal cord, and in the ganglia. As 
its name implies it is of a grayish or ashy color tinged with red, 
darker in negroes than in the white races. In consistence it is 
soft and pulpy, easily broken down by pressure of the finger. 
In minute structure it is seen to consist of a collection of cells 
or vesicles embedded in a fine net-work of filaments called neu- 
roglia (nerve-glue), with some white fibers intermingled. The 
nerve-cells, or corpuscles, are of various shapes, generally sphe- 
roidal or ovoid, with one or more tail-like processes, and a nucleus 
and nucleolus, as shown in the cut. 
Fig. 2.3. — Various Forms of Nerve-Cells. 
3. White Matter. — The white or fibrous nerve-substance is 
found in the central part of the brain, in the outer part of the 
spinal cord, and composes the entire substance of the nerves. It 
is, with some exceptions, of a dead-white color. It consists of 
numerous small fibers united by neuroglia similar to that which 
unites the cells of the gray matter. 
4. Structure of Nerve-Fibers. — Nerve-fibers are of two kinds, 
medullated or white, and non-medullated or gelatinous. The 
latter are found in the nerves of the sympathetic system, the 
olfactory nerve, and to some extent mingled with medullated 
fibers in the spinal nerves. A medullated nerve-fiber consists STRUCTURE AND COMPOSITION OF NERVE-TISSUE. 
159 
of three distinct parts : a sheath, or tube of delicate, transparent 
membrane, (1) the neurilemma; within this a soft, white substance 
known as (2) the white substance of Schwann; in the center of 
this is a gray, thread-like filament, (8) the axis cylinder. At 
intervals constrictions are seen appearing to be due to thicken- 
ing of the neurilemma. The non-medullated fibers have no con- 
strictions, are smaller in size, grayish in color, and consist of a 
sheath containing fine granular filaments. 
5. An entire nerve is composed 
of bundles (funiculi) of fibers held 
together by neuroglia, and the 
whole surrounded by a strong fi- 
brous sheath, the perineurium 
(around the nerve), which sends in 
prolongations of itself between the 
funiculi, thus giving strength to the 
nerve and effectually protecting the 
delicate fibers. The great sciatic 
nerve in the thigh is the largest 
nerve in the body, is about half an 
inch in diameter, and is strong 
enough to support the entire weight 
of the body. 
6. Terminations of Nerves. — Some nerve-fibers convey power 
of motion, others of general sensation, others special sensations, 
as sight, hearing, etc., and still others, which go to the glands, 
have the power of causing secretion; but with all this differ- 
ence of function, neither the microscope nor the chemist’s 
tests can detect any difference of structure or composition 
of these fibers. Hence physiologists have sought to find differ- 
ences in the distant extremities or terminations of the nerves 
and certain “ end organs,” as they have been called, have been 
described as characteristic of nerves performing different func- 
tions. In the voluntary muscles they terminate in small ex- 
pansions on the muscle fiber, or “ end plates,” as they have 
been termed. In the involuntary muscles they form plexuses, 
and terminate in the nuclei of the cells. In the glands the 
Fig. 24. — Structure of Medul- 
lated Nerve-Fiber. 
1, Neurilemma; 2, White substance 
of Schwann; 3, Axis cylinder. 160 
LESSONS IN PHYSIOLOGY. 
axis cylinder is, according to Pfliiger, continued into the gland- 
cell. The terminations of the nerves of smell, sight, hearing, 
taste, and feeling will be noticed in the description of the 
special sense organs. 
7. Chemical Composition of Nerve-Tissue.—About eighty per 
cent of nerve-matter is water. The solid constitutents are 
albumen, fat, and mineral salts. Of the ultimate elements, 
phosphorus is a characteristic constituent. An increase in 
mental activity is always accompanied by an increase in the 
phosphates (salts containing phosphorus) in the excretions 
of the body, showing that the production of nerve-force is 
attended with the destruction of nerve-tissue. 
1. A portion of the sympathetic system may be easily shown in a frog. Make 
an incision the whole length of the abdomen, and remove the viscera. The two 
chains of ganglion with their connecting filaments may be seen lying in front of 
the spinal column. 
2. It is a very easy matter to dissect the thigh of a frog and show the great 
sciatic nerve. If the animal shall have been recently killed, violent contractions 
of the muscles of the leg will take place when the cut end of this nerve is irritated. 
3. It is a very difficult matter to demonstrate the minute structure of nerve- 
tissue. Patient work, with proper chemical preparation of the material, and high 
powers of the microscope, are necessary. 
PRACTICAL ILLUSTRATIONS. 
LESSON 33. 
Functions of the Nervous System. 
1. The Governing Power of the Body. — Imagine a large fac- 
tory in which each laborer worked independently of the others, 
and on such parts of the work as pleased him, with no rules 
or plans, no system or division of labor, and the workers had 
no communication with each other: nothing satisfactory could 
he accomplished. There must be a plan and a governing head, 
and all must work in harmony. In the body one organ works 
in harmony with another. Saliva is secreted in the mouth FUNCTIONS OF THE NERVOUS SYSTEM. 
161 
when the demand for it exists in the stomach. The heart 
pumps the blood to every organ of the body, and is itself con- 
trolled and regulated by the nerve-centers. When we stop 
breathing the heart stops beating, and vice versa. Touch the 
foot with a hot iron and the muscles of the leg contract and 
pull it away. Strike at the eye and the lid is quickly drawn 
down to protect it. When the perspiration is checked by ex- 
ternal cold, the kidneys secrete more abundantly. Thus one 
organ helps another, and all are governed and controlled by the 
great nerve-centers. 
The functions of the nervous system may be stated in gen- 
eral to be : (1) Originating a peculiar activity we call nerve- 
force. This power lies in the cells of the gray matter of the 
brain, spinal cord, and ganglia. If these cells be destroyed 
all nervous phenomena cease. (2) Transmitting nerve-force. 
This is the peculiar function of the white, or fibrous tissue. 
Sever a nerve and the part to which it is distributed is no 
longer capable of action. (3) Receiving impressions from ex- 
ternal sources. This power lies mainly in the terminations of 
the nerves, or “ end organs.” Thus without the retina of the 
eye we could get no impressions of the form and color of ob- 
jects ; without the organ of Corti in the internal ear we could 
not distinguish sounds; and so on through the five special sense 
organs. We get an impression of temperature through the 
terminations of the nerves of common sensation in the skin. 
However, if the optic nerve be severed and the end touched 
a sensation of light is experienced, and in the same way a 
noise is heard if the cut end of the auditory nerve be irritated, 
but there is no perception of objects nor distinguishing of 
sounds. 
The activity of the nervous system, then, consists in receiving 
from without impressions which are transmitted to certain cen- 
ters within, where other impressions originate, prompted by the 
impressions sent in at the time, or originating from former 
impressions (memory), and giving rise to certain motions and 
feelings or sensations. 
2. Functions of Special Parts. — The nervous system is a com- 162 
LESSONS IN PHYSIOLOGY. 
plex apparatus, and we cannot say that all of its details are yet 
thoroughly understood. Experiments on animals, and observa- 
tions on insane people and those with wounded and diseased 
parts, have determined the particular functions of many of the 
special parts in a more or less satisfactory manner. 
3. Function of the Cerebrum. — In general it may be said that 
the cerebrum is the organ of mind. It is the highest organ of 
the body, not only in position but in function. Two funda- 
mental characters of mind are the intellect, or that which knows 
or acquires knowledge, and the will, or that which determines, 
decides, and chooses between alternatives. Consciousness, or the 
knowledge the mind has of its own acts, is inseparable from 
the intellect and the will. The cerebrum is the seat of the 
intellect, the will, and consciousness. If it be removed from a 
frog, the animal sits stupid and apparently lifeless wherever it 
is placed, but if irritated in any way it leaps or crawls. If 
placed on a board which is made to turn slowly so that it would 
fall off, it climbs to the upper side. If thrown into water it 
swims until a support is accidentally touched, and then it 
climbs upon it and remains at rest. But unless some stimulus 
is applied it will not move, although respiration and circulation 
goes on, and if food be introduced into its stomach digestion 
takes place. It is to all intents and purposes a machine, acting 
only as it is acted upon by some external force. It has no 
power of will, or sense to act by itself. When the cerebrum is 
removed from birds they sit stupidly and only move when stim- 
uli are applied, and act generally like the frog under like circum- 
stances. When a man is asleep, the cerebrum appears to be 
inactive. He is not conscious of what takes place around him, 
but may execute all of the acts of a waking individual. A 
patient under the influence of narcotics acts in a similar 
manner. 
Dr. Courmont, a French investigator, has recently announced 
his opinion, based on a series of experiments and observations, 
that the cerebrum is the seat of the higher mental faculties, as 
thought, judgment, comparison, etc., while the cerebellum is 
that of the unreasoning mental processes, as love, hatred, joy, FUNCTIONS OF THE NERVOUS SYSTEM. 
sorrow, etc. The cerebrum, he says, is the organ of sense, the 
cerebellum of sentiment. 
4. Functions of the Cerebellum. — When the cerebellum has 
been removed from a pigeon its gait becomes unsteady, as 
though the muscles of one side did not act in harmony with 
those of the other. It will try to eat, but in pecking at the food 
misses its aim. Similar results have followed when the cere- 
bellum was removed from other animals. Disease of this part 
in the human being has been accompanied by unsteadiness of 
gait, yet the evidence here is contradictory, for in some cases 
extensive disease of the cerebellum was not followed by any 
disturbance of the harmony of muscular action. Foster says: 
“ Still the experimental evidence is so strong that we must con- 
sider the cerebellum as an important organ of co-ordination, 
though we are unable at present to define its functions more 
exactly.” 
5. Functions of the Pons Varolii. — Nothing very definite is 
known of the special functions of this part of the brain, other 
than its evident anatomical use in connecting, by means of its 
fibers, the other parts. It contains a considerable amount of 
gray matter and is probably an aid to the cerebellum in the 
function of co-ordinating muscular movements. 
6. Functions of the Medulla Oblongata This is the great 
center of centers of the nervous system, a kind of vital tele- 
graphic headquarters. Most of the organic functions of the 
body are controlled by nerve-centers located in the medulla. 
Here is found the “ respiratory center,” or a point which, if 
destroyed, respiration immediately ceases, or if irritated breath- 
ing is modified and interrupted. It has been called the “ center 
of life ” and the “ vital knot,” for when respiration ceases all 
other functions quickly cease and death is the result. The 
method of executing criminals once in vogue in Spain consisted 
in forcing a sharp-pointed instrument into this part, through the 
articulation of the atlas and occipital bone. In ordinary hang- 
ing the odontoid process of the axis is forcibly pressed upon this 
part, and death is instantaneous. Closely connected with the 
respiratory center is the “ convulsive center.” In the medulla is 164 
LESSONS IN PHYSIOLOGY. 
also found the “ vaso-motor center,” which controls the calibre of 
the arteries. The phenomena of blushing and turning pale is 
due to variations in this center, whereby a greater or less amount 
of blood is permitted to flow to the small vessels. Here also 
is the “ cardio-inhibitory center,” which controls the force and 
frequency of the heart’s action. The center for deglutition or 
swallowing is located in the medulla. The entire brain except 
the medulla may be removed from an animal, and still swallow- 
ing will take place if the object be pushed into the pharynx. 
The center for peristaltic movements of the stomach are found 
here, and closely related to it the “ vomiting center.” The center 
for the secretion of saliva, and possibly for all other digestive 
fluids, lies here also. 
It will thus be seen that the medulla oblongata is a very im- 
portant part of the nervous system, the headquarters as it were 
of most of the organic or animal functions. 
7. Reflex Action. — This term, so frequently used in all works 
on the nervous system, should be clearly understood by the 
pupil. When we tickle the foot of a. sleeping person, he jerks 
it away without being awakened. If your hand accidentally 
touches a hot surface or a sharp point, you involuntarily with- 
draw it at the same instant you feel the pain. Your eyelids 
involuntarily close when some object suddenly comes near. 
The pupil of the eye contracts in a strong light. Dust drawn 
with the air into the nasal passages causes sneezing. A foreign 
body of any kind in the windpipe produces coughing. The 
sight and smell, or even the suggestion or recollection of some 
disgusting object, may cause vomiting. A word or action or a 
view may cause blushing or pallor. An irritation in the stomach 
may cause irregular and rapid action of the heart. A foreign 
body in the ear has been known to cause a troublesome cough. 
A laceration of the foot may cause rigidity of the muscles of 
the jaw, or “lock-jaw,” as it is called. A crushed finger or toe 
may cause intense nausea and sickness of the stomach. A 
chicken jumps about after its head is severed from its body. 
The snake's tail moves for hours after the body has been cut to 
pieces. All of these and many others that might be mentioned 
are examples of reflex action. FUNCTIONS OF THE NERVOUS SYSTEM. 
165 
Three things are necessary for reflex action: (1) a nerve- 
center; (2) a nerve-termination; (3) nerve-fibers connecting 
the two. Reflex action may be defined as an impulse received 
by a nerve-termination, conveyed to a nerve-center from which 
another and different kind of impulse is conveyed to a nerve- 
termination along a nerve-fiber, resulting in motion in the part 
in which the nerve-fiber terminates. The impulse passing from 
the nerve-termination to the nerve-center is called an afferent 
impulse and the nerve-fiber conveying it is called a sensory 
nerve-fiber. The impulse passing from the nerve-center to the 
part moved is called an efferent impulse, and the nerve-fiber a 
motor nerve-fiber. The spinal nerves contain both motor and 
sensory fibers. Some of the cranial nerves contain all motor 
fibers, others all sensory, and some are mixed like the spinal 
nerves. (See Table of Cranial Nerves in Lesson 31.) 
8. Functions of the Spinal Cord. — From the fact that the 
spinal cord contains both white and gray matter, one would 
infer that it acts both as a conductor and a center of nerve- 
force. Experiments on animals and observations in cases of 
disease show that it is a great center of reflex action. Many 
impulses never reach the brain, but are, as it were, reflected by 
the cord. Thus the brain is relieved of part of its work. When 
we gently tickle or touch the limbs of a sleeping person the 
impulse received is conveyed no farther than to the cord, and 
from there may come back a motor impulse which causes the 
limb to move. Thus a sleeping person brushes away the flies 
while the mind is all unconscious of their presence. If, how- 
ever, the tickling or irritation be more severe or long-continued, 
the impression goes into the brain and consciousness is aroused, 
or in other words, the person is awakened. 
Pfliiger made some experiments on frogs which would seem to 
prove that to a certain degree the spinal cord possessed intelli- 
gence if not consciousness. He removed the brain of the frog 
and touched the thigh with acetic acid. The animal rubbed the 
place with the foot of the same side. He then cut off this foot, 
and after an ineffectual attempt to reach the place with the 
stump, it rubbed the place with the other foot. These experi- 166 
LESSONS IN PHYSIOLOGY. 
ments have been repeated by others with the same results. 
Rattlesnakes in the act of striking have had their heads instantly 
cut off. The headless trunk would sometimes repeat the stroke. 
This, however, would appear to be the force of habit, making an 
otherwise voluntary act a reflex act. 
The white matter of the cord acts as a conveyer of impulses 
to and from the brain. If we will to move a foot, or if some- 
thing touches the foot, efferent and afferent impulses evidently 
pass along the whole length of the spinal cord to and from the 
brain. The anatomical fact that the sum of all the nerve-fibers 
in the cord is less than the sum of all the fibers of the spinal 
nerves, would preclude the idea that the impulse is conveyed by 
one continuous fiber. It is more probable that the gray cells in 
the cord act as relays which, as it were, strengthen the impulse 
and pass it on to other cells in succession, and thus the impulse 
reaches the brain. In this respect it resembles an ordinary tele- 
graphic system, where batteries (called relays) along the route 
renew the electric current. 
9. Automatic Reflex Action. — There are many acts performed 
by men and animals which cannot be attributed to the will, 
nor to simple reflex action. Thus respiration is a rhythmic 
action kept up apparently by nerve-cells in the medulla oblon- 
gata, without external stimulus and only partially capable of 
being modified by the will. The beating of the heart is another 
rhythmic action not due to external stimuli, and entirely inde- 
pendent of the will. The heart will beat a few times after it is 
severed from the body in higher animals, and in turtles it will 
beat for two hours, even after all blood is washed out of it and 
it becomes dry on the surface. Here the action must be due to 
the ganglia, which are found in the heart-substance. In this 
class of actions we may place secretion of the glands, although 
in some cases external influences doubtless provoke them to 
action. The salivary glands are caused to secrete more abun- 
dantly by the presence of food in the mouth, and even by the 
taste and smell of food. The peristaltic action of the stomach 
and intestines is also automatic, although modified by the pres- 
ence of the food. FUNCTIONS OF THE NERVOUS SYSTEM. 
167 
10. Higher Automatic Action. — A higher form of nerve-activ- 
ity is that proceeding from the cerebrum. Place an animal on 
the floor in its natural position when at rest. If its breathing 
and circulation go on, and it otherwise remains motionless, there 
is no activity of its cerebrum manifest to the observer. If 
touched or irritated and it moves, we cannot say it is activity 
of the cerebrum, for headless animals may do that. But if all 
causes of irritation be absent and the animal moves, we can say 
it is from a force proceeding from the cerebrum, and call it voli- 
tion, or purely automatic; that is, self-action. If a loud noise be 
made, or some object be presented to its view, and it then 
move, it may be from reflex action or from volition, we cannot 
tell which. The noise or the view may make an impression of 
fear on the auditory or optic nerve, and this sent to the spinal 
cord through the brain incite involuntary motion. Examples 
of this are seen in persons involuntarily jumping from a sudden 
sound, or when they unexpectedly come upon a strange object. 
The movements are purely involuntary and therefore reflex. 
But, on the other hand, in the case of the animal, we do not 
know but the sound or the view may simply excite the appre- 
hension of the mind of the animal, and its movements be purely 
voluntary and made for the purpose of getting away from the 
danger. 
Volition, then, seems to come from within and be independent 
of external stimuli, yet we do not know but that it is a result 
of impressions previously received through the sensory nerves 
and stored up in the cells of the brain, to be given out later in 
the form of voluntary motion. Would a being without the 
senses of smell, touch, taste, hearing, sight, temperature, and 
common or general sensation (pain) exhibit will power or con- 
sciousness ? This is a question yet to be answered. Going to 
sleep is the shutting out of all external impressions, and sound 
sleep is perfect quiescence of the cerebrum. 
This higher automatism to a great extent governs and con- 
trols all other forms of nerve-activity. We can by exercise of 
the will check, or resist, the tendency to motion caused by 
tickling the extremities. Persons with strong wills resist to a 168 
LESSONS IN PHYSIOLOGY. 
certain degree the encroachment of disease and are enabled to 
endure great bodily injuries without showing signs of pain. 
11. Force of Habit. — Reflex action is of great value to the 
individual, for it enables him to perform various kinds of move- 
ments and carry out different trains of thought at the same 
time. We walk and work and eat to a great degree automati- 
cally. When we are learning to do a certain kind of work, it 
requires our whole attention, but after we become accustomed 
to doing it, the work goes on while the mind may be occupied 
with something else. If the child in learning to walk does not 
give it the entire attention of its mind, it will lose its balance 
and fall, but after a while it is enabled to balance itself and 
move easily without taking a thought. The same is true in 
learning to read and to write. We must at first give them our 
entire attention, but after a while it becomes automatic and the 
words are repeated and the hand forms the letters unconsciously. 
It is fortunate for us also that breathing and the beating of the 
heart and other so-called organic movements are independent 
of our wills, for if they were not we would neglect them when 
some new activity was demanded. A few moments’ neglect 
of these essential motions would be fatal. 
12. Sleep and Dreaming. — Sleep is the cessation more or less 
complete of cerebral activity. During this period repair of the 
entire system goes on, and the excess of waste over repair 
during the waking moments is counterbalanced. Dreams are 
the result of partial and unco-ordinated activity of the cerebrum. 
It is believed from some experiments and observations which 
have been made, that dreaming takes place the very instant of 
waking. It is strange how in a moment one may dream of 
occurrences which would occupy days, even years, in their 
fulfillment. Dreams to a great extent depend upon the nature 
of the actions and thoughts of the previous waking moments. 
Different times, places, and individuals are mingled in the 
strangest confusion in dreams. It is curious to note how ex- 
ternal causes may determine the nature of a dream. Thus the 
firing of a gun, or a clap of thunder may cause one to dream 
of a battle. Dr. Reid had a blister on his head and dreamed FUNCTIONS OF THE NERVOUS SYSTEM. 
169 
of being scalped by Indians. Complicated mental operations 
are sometimes performed in sleep, such as the solving of mathe- 
matical problems, inventing machines, etc. Coleridge com- 
posed a poem while asleep, and on awaking seemed to have 
a distinct recollection of the whole of it. He instantly began 
to write it down, but when he had written fifty-four lines he 
was called away on business, and when he returned he had 
forgotten the remainder and could never recall it to mind with 
sufficient distinctness to complete the poem. 
Nightmare is an intensified form of dreaming in which the 
person imagines himself in a distressing situation and unable 
to help himself. It is a result of imperfect circulation of the 
blood. Somnambulism is a condition in which the person per- 
forms, during sleep, the actions naturally belonging to the wak- 
ing state, as walking, climbing, etc. It is peculiar to certain 
persons, and it is difficult to trace it to any special cause. 
13. Functions of the Sympathetic System. — The sympathetic 
nerves are distributed mainly to the organs in the thorax, abdo- 
men, and pelvis, and are intimately connected with the functions 
of digestion, respiration, circulation, secretion and excretion, and 
nutrition. These are called organic functions because they 
distinguish a living organism, that is, a plant or animal from 
inorganic or mineral matter. These nerves are therefore 
called the nerves of organic life as distinguished from the 
encephalo-spinal nerves, which are the nerves proper of animal 
life. It frequently happens that when one organ is diseased 
or irritated a disturbance in the functions of another organ 
occurs. Thus an irritation of the stomach may cause labored 
respiration or palpitation of the heart. One organ is thus said 
to sympathize with another. The sympathetic nerves were sup- 
posed to be the media of these peculiar reflex actions, hence 
the name sympathetic system. 
NOTE. 
There are a number of experiments which might he performed on living ani- 
mals, which would illustrate functions of the nervous system, but they are not of 
a nature to he practicable in an ordinary school. The teacher should call special 
attention to the experiments alluded to in the text. All pupils will have observed LESSONS IN PHYSIOLOGY. 
the motions of decapitated fowls, and many will have noticed the movements of 
frogs, turtles, and snakes when killed. Also the actions of sleeping persons have 
been observed. By proper questioning the teacher may bring the combined expe- 
rience of the class on these subjects, and this exercise will be a very good substi- 
tute for actual laboratory experiments. 
LESSON 34. 
Hygiene of the Nervous System. 
1. Healthy Condition of Other Organs. — The parts of the body 
are mutually dependent. When one suffers, all must suffer 
more or less. Good digestion, depending mainly on good food, 
properly prepared, in proper quantity and taken under proper 
conditions, tends to produce good blood, and this favors healthy 
secretions, proper excretion, and proper nourishment of all the 
tissues. The condition of the nervous system depends largely 
upon the nourishment of nerve-tissue. But muscular exercise 
and rest in proper proportion are also necessary for good diges- 
tion and perfect circulation and excretion. Proper action of 
the respiratory system, so that the blood gets the proper amount 
of oxygen free from injurious admixtures, and proper attention 
to cleanliness and evacuation of excretions, are also necessary 
for the general health. Hence, the hygiene of the nervous 
system demands attention to all other hygienic laws. 
2. Excitement and Emotion. — The mind and body have a re- 
ciprocal action. Anything that disturbs the mind, as paroxysms 
of anger, excessive fear and grief, even excessive joy, disturbs 
the functions of digestion, secretion, respiration, and circulation, 
through the nervous system. The nutrition of the tissues in 
general is thus impaired, and the nerve-tissue suffers with the 
others. The nerve-tissue thus changed cannot act in a normal 
manner, and the mind is disturbed through the body. Insanity 
is generally the result of unrestrained passions and emotions. 
Many persons give way to passions and emotions which an 
educated will would have checked and held in abeyance. Yet HYGIENE OF THE NERVOUS SYSTEM. 
171 
there is often danger in sudden and complete suppression of the 
expression of emotion. Tears and words are often the safety- 
valves which relieve the tension of the nervous system. But 
brooding over misfortunes and stirring up resentment are plain 
violations of a natural hygienic law. 
3. Work and Worry. — Some persons can endure without 
injury much more mental labor than others. Agassiz defined 
genius as a capacity for an infinite amount of work, and it is 
generally true that those who have distinguished themselves in 
any particular field have done it by a vast amount of mental 
labor. Sometimes it has been at the expense of a broken-down 
constitution and a shortened life, but we have plenty of instances 
of men and women living to old age and having labored from 
youth up almost every minute of their waking existence. It is 
not mental work simply that kills. It is misdirected mental 
work, and mental worry. The mind needs a diversity of em- 
ployment, so that different nerve-cells are called into activity 
in proper alternation. He who is content to do what he can, 
properly varying his work, and does not worry over the results, 
will accomplish the most with the least expenditure of nerve- 
force. Dr. George M. Beard says: “Worry is the converse of 
work; the one develops force, the other checks its development 
and wastes what already exists ; work is growth; worry is inter- 
ference with growth. Worry is to work what the chafing of a 
plant against the walls of a green-house is to the limitless 
expansion in the free air. In the successful brain-workers 
worry is transferred into work.” 
4. Rest. — What has been said in the lesson on Hygiene of 
Muscles in regard to exercise and rest applies also to the ner- 
vous system. It is probably true, however, that nerve-activity 
can be kept up longer without injury than muscular activity. 
Except when asleep the mind is ever active. We are always 
thinking of something, however important or trivial that some- 
thing may be. It is the constant attention of the mind to one 
train of thought that tires it. Change is rest. A change of 
work is frequently a recreation, and the best possible kind of 
rest. Pure recreation or sport is, however, necessary especially 172 
LESSONS IN PHYSIOLOGY. 
to some persons. Some of the greatest thinkers and brain- 
workers have made a habit of resting their brains by indulging 
in some trivial amusement or occupation. Darwin, one of the 
most industrious of naturalists, whose labors have revolution- 
ized the study of science, indulged, as a habit, in reading very 
light fiction. Milton, whose “Paradise Lost” was the greatest 
intellectual achievement of his age, was accustomed to practic- 
ing the sword exercise. 
“ Rest,” says Judge Tourg6e, “is that change of occupation; 
rest is that relaxation of attention; rest is that putting of the 
mind in a new channel, or in a new course, that gives to the 
overstrained nerves — that gives to the worn body — that gives 
to the weary heart, relaxation. A man may rest and work like 
a horse all the time ; a man may do more resting than most 
people ever dream of, and yet do more work than most of us 
ever know of.” 
5. Sleep. — “Sleep,” says Shakespeare, “knits up the raveled 
sleeve of care.” Young defines it as “ Tired nature’s sweet 
restorer.”. Truth and poetry are here happily commingled. 
One can scarcely get too much natural sleep. A man gains 
nothing by robbing himself of sleep. He simply robs himself 
of vitality. During sleep a man’s physiological bank account 
is increasing, and during waking it is being drawn upon. 
Physiological bankruptcy will soon follow a continued encroach- 
ment of labor or amusement upon the amount of time that 
should be devoted to sleep. The hours of darkness are the 
most favorable to sleep. The best time to rise is just at day- 
light, and the best time to retire is at such an hour as will give 
a proper amount of sleep before daylight. The proper amount 
varies with the individual. In adults from six to nine hours is 
usually enough. Children and very old people require more. 
The young babe sleeps most of its time and grows and gains 
strength rapidly. 
Persons are often kept from sleep by their minds dwelling 
upon their business or social affairs. It is not always possible 
to avoid this, but the best way is to make an effort to fix the 
mind momentarily on some subject entirely outside of the regu- 173 
HYGIENE OF THE NERVOUS SYSTEM. 
lar channel of thought, changing from one subject to another 
as frequently as possible; in other words, make an effort to 
cause the mind to wander. Try to recall the pleasant incidents 
of the past, or build air-castles for the future, but do not think 
about your daily affairs. 
6. Effects of Alcohol on the Nervous System.—As alcohol acts 
on all organs through its action on the nervous system, it would 
naturally be supposed that the nervous matter itself would be 
injured, and such is the case. One of the first effects of alcohol 
is a flushing of the face and a feeling of warmth on the surface 
of the body. This is due to the quickened action of the heart 
and the dilation of the small blood-vessels from the effects of 
alcohol on the nerve-centers controlling these organs. The 
mind is at first more active, because the little vessels of the 
brain are dilated and blood is sent more freely to that part. A 
little later the alcohol begins to disturb the reflex and co-ordi- 
nating powers of the nervous system, and ordinary muscular 
inovements are performed imperfectly and with difficulty. Still 
later, the will power and judgment becomes paralyzed and only 
the emotional and impulsive instincts of human nature are left, 
and these being no longer under control of the higher faculties 
of reason and judgment, are liable to cause the individual to act 
in an irrational manner. In the last stages consciousness and 
volition are lost, and only that part of the nervous system 
which governs circulation and respiration remains. In other 
words, the man is “ dead drunk.” A large quantity may pro- 
duce death by paralyzing all nerve-centers, and thus putting an 
end to all organic functions. This over-action and irregular 
action of the nerves, when repeatedly occurring, has the effect 
finally of weakening the nerve-tissue. 
Says Dr. George M. Beard: “ There is scarcely a nervous 
disease known to science that excess in the use of alcoholic 
liquors may not bring on or aggravate. General debility, neu- 
ralgia, insomnia, epilepsy, paralysis of every form and type, 
insanity in all its grades, as well as delirium tremens, may find 
in alcohol their exciting and predisposing cause.” But the 
worst of all is the moral effect of long-continued excess. The 174 
LESSONS IN PHYSIOLOGY. 
brain degenerates and the mind loses control over the appetite 
for spirits. “ Pledges of total abstinence, fear of disgrace, loss 
of social position, loss of friends and family, apprehensions for 
this world or the next, all these considerations have no more 
weight against this disease [chronic alcoholism] than they 
would have against smallpox or typhoid fever.” 
7. Effects of Tobacco on the Nervous System. — While there are 
many persons, especially among those in adult life, whom 
tobacco does not apparently injure, there- are some who are 
particularly affected by even a moderate use of the weed. 
There are persons who have a nervous diathesis, that is, a ten- 
dency to nervous diseases. This condition is more prevalent 
in this country than in Europe, probably an effect of our drier 
climate. Tobacco is especially injurious to such persons. They 
become “ nervous,” suffer from sleeplessness, melancholy 
spirits, trembling, headaches, and sometimes disturbance of 
vision. 
8. Tea, Coffee, and Chocolate. — These beverages have usually 
a peculiar soothing and sustaining effect on the nervous system 
when taken in moderate quantities by adults. Their beneficial 
effects are more particularly noticeable in persons past the 
middle age. But there are some organizations which cannot 
tolerate them in even moderate quantities, and when used to 
excess they are frequently very injurious. Children should not 
use them, and adults should observe their effect on themselves 
and deny themselves if evil results appear to be due to their 
use. They are inclined to produce wakefulness in some persons, 
and in others tremblings. 
In such cases they should not be used. If a warm drink is 
needed a harmless substitute for these beverages is found in 
“ Cambric tea,” which is simply hot water and milk sweetened 
to taste. It is a great mistake to drink tea or coffee for the 
purpose of keeping awake in order to prolong the hours of 
labor. Their power for evil is thus trebled, for there is com- 
bined with the effect of over-stimulation of the nerves the loss 
of the necessary sleep and excessive labor. 
9. Opium and Morphine. — These drugs are valuable agents HYGIENE OF THE NERVOUS SYSTEM. 
175 
in the hands of a skillful physician, but anything like an habit- 
ual use of them or even a frequent use of them in cases of 
sickness is exceedingly dangerous. They rapidly gain a power- 
ful hold on the individual, blunting his moral sense and de- 
stroying his will power so that he becomes an abject slave to 
the appetite for them. Those who suffer frequently from 
neuralgia and other painful affections should be very careful 
in using these drugs lest a habit of taking them be acquired, 
a habit which will grow with the indulgence until finally all 
power to quit their use is lost, and the patient is a helpless 
victim of a drug which in a few years will make him a mental 
and physical wreck. 
10. The Use and Abuse of Quinine. — This is one of the most 
valuable of medicines, good in a great variety of cases, and in 
the hands of a skillful physician one of the greatest of bless- 
ings. But of late years many persons are in the habit of 
prescribing it for themselves in every slight ailment, and many 
have become slaves to it, taking it as regularly as they would 
alcoholic liquor or opium, and although the result is not so 
serious as in case of the latter drugs, it is bad enough. 
11. The Effect of Medicines in General on the Nervous System. 
— The human system is so constituted that- it seems to acquire 
gradually the power of tolerating even very poisonous medi- 
cines, the nervous system constantly requiring more and more 
to produce the same effect, until finally it breaks down under 
the load, and a general collapse of the whole organization fol- 
lows. Thus one may begin with the ordinary dose and by 
gradually increasing it an amount may be taken without im- 
mediate danger which would under other circumstances cause 
death. But the end comes finally in a broken-down constitu- 
tion. The lesson taught by the victims to the habitual use 
of narcotic drugs should not be lost on those who are yet free 
from the bondage of habit. Drug medicines are but necessary 
evils. He is wise who uses them only in cases of actual neces- 
sity. 176 
LESSONS IN PHYSIOLOGY. 
EXERCISES FOR REVIEW. 
1. Is the size of the brain a measure of mental power ? What relation has 
the relatively greater quantity of gray matter to intellect ? 
2. What are the uses of the membranes covering the brain ? 
3. Name the divisions of the nervous system ; of the brain. 
4. What part of the cerebrum is gray matter? of the cerebellum? of the 
spinal cord ? 
5. What are the ventricles of the brain ? What lines them ? Their contents ? 
6. How does the dura mater of the spinal cord differ from that of the brain ? 
7. What is the “ arbor vitse ”? 
8. Where are nerves most numerous ? 
9. Name the cranial nerves in order, giving the origin, distribution, and func- 
tion of each. 
10. What is the effect of cutting the anterior root of a spinal nerve ? the pos- 
terior root ? both roots ? the nerve itself ? 
11. What is the “abdominal brain”? Explain why a severe blow on the 
abdomen may cause death without breaking the tissues. 
12. What is the structure of gray matter ? of white matter ? How do they 
differ in function ? 
13. Neurilemma? Perineurium? Neuroglia? 
14. How do nerves terminate ? 
15. What is a characteristic chemical element of nerve-substance ? 
16. State the functions of the nervous system in general terms. 
17. Where is the seat of the intellect ? of will ? of consciousness ? 
18. Where is the “vital knot”? Why is death by hanging instantaneous 
and painless ? 
19. Locate the following centers: the respiratory, vaso-motor, cardio-inhibi- 
tory, vomiting center. 
20. Define reflex action. What are the functions of the spinal cord? 
21. Automatic action. 
22. Define sleep and dreaming. 
23. What is meant by the “ nerves of organic life ”? 
24. Define rest. Why do so many men succumb to “ overwork ”? 
25. What is the proper amount of sleep for an adult ? 
26. When is alcohol injurious to the nervous system ? Why ? 
27. Do not permit yourself to become a slave to habits of eating, drinking, or 
taking medicines. Why is this good advice ? CHAPTER II. 
HOW THE BODY COMMUNICATES WITH THE EXTERNAL WORLD, 
OR THE SPECIAL SENSE-ORGANS. 
LESSON 35. 
The Structure of the Eye. 
1. The Orbits. — The human eye is peculiarly well protected 
in its bony socket. Nothing but a well-aimed thrust of a com- 
paratively sharp instrument can injure it. Ordinary blows are 
sure to be received by the prominent cheek-bone below or the 
edge of the frontal above. It is also protected from shocks by 
a cushion of soft material. The cavity of the orbit is conical 
in shape, and the space not occupied by the eye and its appen- 
dages is filled with loose areolar tissue containing fat. 
2. The Eyeball. — The eyeball is in the shape of a sphere, with 
the segment of a smaller sphere grafted upon it, making the 
diameter from before backward a little greater than the lateral 
diameter, which is about one inch. The eye is apparently set 
in a slit in the skin of the face, but really this is not the case, 
for the skin of the eyelids turns over their edge and becomes 
here a thin, transparent, smooth, and exceedingly sensitive 
mucous membrane, the conjunctiva, which lines the lids and is 
reflected over the front part of the eyeball itself, so that the 
eye is really behind the skin. 
The eyeball is capable of being turned in all directions by six 
little muscles which have their origin in the back part of the 
orbit. The superior rectus turns the eye upward, the inferior 
rectus turns it downward, the external rectus turns it outward, 178 
LESSONS IN PHYSIOLOGY. 
and the internal rectus turns it inward. The superior oblique 
muscle passes forward through a loop near the upper, inner 
front part of the orbit, then turns and passes over the eyeball 
and is attached to it at its outer side. Contracting, it turns the 
eye outward and downward and rotates inward. The inferior 
oblique acts as an antagonist of the superior, and turns the eye 
inward and upward and rotates it outward. “ Cross eyes ” and 
“ wall eyes ” are caused by too great contraction, the former of 
the internal rectus, and the latter of the external rectus. The 
defects may be remedied by cutting the proper muscle with a 
suitable instrument and permitting it to become attached to a 
new point. 
Fig. 25.—Muscles of the Eyeball. 
3. The Sclerotic Coat. — The eye is a globular receptacle filled 
with transparent fluids. The walls of the receptacle are three in 
number, closely attached to each other, and called respectively, the 
outer or first, the middle or second, and the inner or third tunic. 
The outer tunic is in two parts, one opaque, the other trans- 
parent. That part which covers about five-sixths of the eye and 
is of a pearly white color is called the sclerotic coat. The part 
of it which we can see is called the “white of the eye.” It THE STRUCTURE OF THE EYE. 
179 
is a very tough, dense membrane, rigid enough to give shape 
to the eyeball, yet elastic and yielding to pressure. The muscles 
of the eye are inserted into it, and it is perforated at the back 
part for the entrance of the optic nerve. It consists of white 
fibrous tissue mingled with fine elastic fibers and fusiform nucle- 
ated cells. The existence of nerves in it is doubtful, and the 
blood-vessels are few in number. The veins we see in the white 
of the eye when it is “ blood-shot ” are in the conjunctiva, which 
is so transparent that we do not see it except when its vessels 
are engorged. 
4. The Cornea. — The anterior sixth of the first tunic is called 
the cornea. It is perfectly transparent and fits into the sclerotic 
coat like the crystal of a watch in its case. In outline it is 
almost circular. Is is composed of three layers, not including 
the conjunctiva, which covers it in front. The outer layer is 
composed of transparent fibers, continuous with those of the 
sclerotic coat. The middle layer is an elastic membrane which 
maintains the curvature of the cornea. The inner is a layer of 
epithelial cells. It contains numerous nerves, but no blood-vessels 
nor lymphatics. The cornea is the window through which light 
enters the interior of the eye. 
5. The Choroid Membrane. — That part of the second tunic 
which lines the sclerotic coat is called the choroid membrane. 
It is connected to the sclerotic by fine cellular tissue. It con- 
sists mainly of a dense net-work of capillary vessels interspersed 
with pigment cells, which give it a dark brown appearance. In 
albinos the pigment, or coloring matter, is absent and the choroid 
is red from the blood showing through the translucent vessels. 
Like the sclerotic it is pierced behind for the entrance of the 
optic nerve. 
6. The Ciliary Processes. — At the junction of the sclerotic with 
the cornea the choroid membrane is gathered into a circular, 
plaited curtain, or series of converging folds from sixty to eighty 
in number, surrounding the crystalline lens. These folds are 
called the ciliary processes. Beneath this and attached all 
around to the sclerotic coat is a muscular ring with radiating 
fibers called the ciliary muscle. 180 
LESSONS IN PHYSIOLOGY. 
7. The Iris. — We speak of a person’s eyes as blue, brown, 
black, or gray, but all this “ color of the eyes ” is simply the 
color of a peculiar circular adjustable curtain with a round hole 
in its center. This curtain is called the iris, and the hole the 
pupil of the eye. The pupil always appears black because we 
look through it at the black choroid membrane in the back part 
of the eye. In the albino it appears red because the choroid 
membrane is red. The iris lies behind the cornea and in front 
of the crystalline lens, and is attached to the choroid membrane 
by its circumference and by the ciliary ligament to the sclerotic 
coat and cornea. It forms, 
together with the choroid 
and ciliary processes, the 
second, or middle tunic. 
It consists of a layer of 
many sided cells, contain- 
ing a pigment matter in 
front, behind which is a 
framework of fibers and 
cells, and back of this are 
two sets of involuntary 
muscular fibers, one run- 
ning in a circular man- 
ner, the other radiating. 
When the circular fibers 
contract the diameter of the pupil is lessened ; when these fibers 
are relaxed the diameter of the pupil is increased by the elas- 
ticity of the radiating fibers. 
8. The Retina. — This is the expansion of the optic nerve and 
constitutes the whole of the inner or third tunic. It is a semi- 
transparent membrane lying close to the choroid and extending 
nearly to the ciliary processes in front. It consists of ten layers 
of variously shaped cells and fibers. The ninth layer, counting 
from within outward, is called Jacob’s membrane, and consists of 
rod-like and cone-like bodies which appear to be the real termi- 
nation of the optic nerve. The point where the optic nerve 
enters is about one-tenth of an inch to the inner or nasal side of 
A, Cornea; B, Aqueous humor; C, Pupil; D, Iris; 
E, Crystalline lens ; K, Vitreous humor; 
L, Optic nerve; F, Sclerotic; G, Choroid; 
H, Retina. 
Fig. 26. — A Section of the Human Eye. THE STRUCTURE OF THE EYE. 
181 
the center. Here there are no rods and cones, and experiments 
have demonstrated this spot to be blind. In the exact center of 
the retina is a slight elevation with a central depression at its 
center. As we approach this central spot (the macula lutea, or 
“ yellow spot,” as it is called) the cones become more numerous 
and much smaller. Le Conte says they are only of an 
inch in diameter, and there are probably a million in a square 
of an inch. It is at this point that vision is most perfect. 
9. The Aqueous Humor. — The cavity of the eye is filled by 
three transparent bodies, called humors. That occupying mainly 
the space behind the cornea and in front of the iris is called the 
aqueous humor. A very little of it lies in the space behind the 
iris, communicating with that in front through the pupil. It is 
a clear liquid, consisting mostly of water with alkaline salts in 
solution. If the cornea be punctured the aqueous humor escapes, 
the protuberant part of the eye collapses, and the sight is tempo- 
rarily lost. The wound will, however, heal in a short time and 
a new supply of liquid will be secreted and sight restored. 
10. The Vitreous Humor. — The large cavity enclosed mainly 
by the retina contains a thick, jelly-like transparent albuminous 
substance, called the vitreous humor. It is contained in a 
transparent membrane, called the hyaloid membrane. Meshes 
of transparent fibers divide the mass into compartments. 
11. The Crystalline Lens. — This name is misleading, for al- 
though it is really a lens in itself, it forms in the eye only a 
part of a lens, the other parts being the vitreous and aqueous hu- 
mors and the cornea. It is described as one of the humors of the 
eye although it is not a liquid but a solid body, easily compres- 
sible and elastic. It is in the shape of a double convex lens, 
about one-third of an inch in diameter and one-sixth of an inch 
in thickness in the center. It is enclosed in a transparent bag, 
called the capsule of the lens. This capsule is attached to the 
sclerotic coat near the junction of the cornea. 
12. The Protectors of the Eye. — Not only is the eye well pro- 
tected by its location, but it has in addition certain guards and 
defenders. The eyebrows shield it from excessive light and direct 
the perspiration to one side and possibly catch some particles of 182 
LESSONS IN PHYSIOLOGY. 
dust that otherwise would get into the eye. The eyelids, com- 
posed of a piece of cartilage covered with skin and lined with 
the mucous membrane, act both reflexively and voluntarily, clos- 
ing instantly when danger approaches. Their edges contain 
small glands (Meibomian glands) which secrete an oily fluid 
which prevents the tears from overflowing on the face and keeps 
the lids from growing together. The cilia, or eyelashes, act as 
shades to the eye and as feelers to warn of danger in the dark. 
The conjunctiva has already been described. It being highly 
sensitive, warns us of the danger of permitting particles to 
remain in contact with the eye. 
13. The Lachrymal Apparatus. — This is an additional means 
of protection to the eye, and consists of the lachrymal gland, 
with excretory ducts, the lachrymal canals, the lachrymal sac, 
and nasal duct. The lachrymal gland is located in the upper, 
outer part of the orbit, and pours its secretion through several 
ducts upon the eyeball. The constant winking keeps it dis- 
tributed over the eye. It is prevented from flowing off upon 
the face, unless in excessive quantity, by the oil from the Meibo- 
mian glands. The orifices of the two lachrymal canals open at 
the inner corner of the eye and receive the fluid. They empty 
it into the lachrymal sac, and this discharges it into the nasal 
duct which opens in the nasal cavity. Here it evaporates as 
fast as discharged. When the secretion is excessive it flows 
over the lids on the face in the form of tears. The tears con- 
sist mostly of water containing salts in solution, common salt, 
or chloride of sodium, being most abundant. The use of the 
lachrymal fluid is obvious. It maintains the clearness of the 
eye by keeping it moist, and washes dust and foreign particles 
away and protects the delicate mucous membrane from the 
irritating effect of the air. 
PRACTICAL ILLUSTRATIONS. 
1. Secure from the butcher the eyes from an ox, pig, or sheep. If possible 
get several specimens to use in case one is spoiled in dissection, and also that 
you may try different methods of preparing them for illustration. Place in 
water until ready for use. PHENOMENA OF VISION. 
2. After removing the fatty tissue, observe the shape of the eyeball, the 
firmness and toughness of the sclerotic coat, the size and point of entrance of 
the optic nerve. Portions of the muscles of the eye will also be seen. With a 
sharp knife cut through the tissues at the junction of the cornea with the 
sclerotic coat. A slight squeeze when the opening is made large enough will 
cause the crystalline lens to come out. The aqueous humor and part or all of 
the vitreous will also escape, and the eyeball will partially or wholly collapse. 
3. Examine the crystalline lens. Observe its form and transparency. Lay it 
over a letter or word of fine print and observe that it magnifies like a micro- 
scopic lens. Put it in water and boil it. Observe that it at once turns white 
and opaque, and after it has boiled several minutes it will split open in three 
triangular pieces, and the surface may be peeled off like the coats of an onion. 
4. Observe the vitreous humor which will flatten out and resemble very much 
the fresh white of an egg. 
5. Now cut through the tissue further and turn the eye inside out as you 
would a ball cover. Observe the blackness of the choroid membrane. The 
ciliary processes will have been partially destroyed perhaps by the rude handling 
necessary in cutting the tough sclerotic coat, but a partial idea of them can be 
had. The iris will not show very well, as it is difficult to isolate it. 
6. Take another eye and boil it for a quarter of an hour. Then cut it 
through from before backward. The general relation of the parts may be 
seen. Try also, if convenient, the method of freezing an eye, and then make 
sections as before. 
LESSON 36. 
Phenomena of Vision. 
1. The Eye as an Optical Instrument. — If you make a pin hole 
in the end of a box, and throw a dark cloth over your head as 
you look down into the box so as to exclude all light except that 
which comes through the pin hole, you will observe an inverted 
picture of any strongly illuminated object which may be in front 
of the hole. A box so arranged is a camera obscura (“ dark 
room ”). A smaller and more distinct image may be made by 
enlarging the hole and placing in it a convex lens which has 
the power of converging the rays of light to a point called the 
focus. In this case the surface on which the picture is to be 
received must be placed in the focus of the converging rays; 
hence it will be necessary to put in a movable screen which can 184 
LESSONS IN PHYSIOLOGY. 
be adjusted to the proper distance. The distance of the focus 
from the lens depends upon the convexity of the latter, the more 
convex the closer the focus, and vice versa. To get the best 
results the sides of the box should be painted black so that all 
rays which strike the sides may be absorbed, otherwise they 
would be reflected upon the picture and obscure it. Such a box, 
with either an adjustable lens or adjustable screen, is the ordinary 
camera obscura. 
Now let us see how nearly the eye corresponds to a camera 
obscura. The cornea is the window which first admits the light 
coming from objects. The pupil is the small hole which admits 
Fig. 27. — The Retinal Image. 
it to the dark chamber. The retina is the screen on which the 
picture falls. The choroid membrane answers to the dark 
colored walls and absorbs the indirect rays. The transparent 
parts of the eye all combine to form the lens which con- 
verges the light. We thus see that the eye is a perfect camera 
obscura. 
2. The Picture on the Retina. — As we have seen, the camera 
obscura produces a miniature picture or image of the objects in 
front of it, and that the eye is constructed in all essential par- 
ticulars exactly like such an instrument; hence there must be 
an image formed on the retina very much reduced in size, but 
perfect in distinctness. This image is in some way, difficult for 
us to understand, translated to the mind through the optic nerve 
and brain, and this translation constitutes the sense of sight. It 
may be asked, since the image is inverted on the retina, how is PHENOMENA OF VISION. 
185 
it that we see objects in their upright position. It is true it 
appears inverted to another eye looking at it as a picture, but it 
does not follow that it is thus translated to the mind. We are 
not conscious of an image in our own eyes, in fact, we are not 
conscious of having eyes at all unless we see them in a mirror 
or have some pain or uneasiness in them, or our attention is 
called to the fact in some way. The mind refers all sensations 
to the direction from which they come. All images are, as it 
were, projected into space outside of ourselves. When you see 
a horse ten feet away you think of it as a horse at that distance, 
and not as an image in the eye. The image is inverted on the 
retina because the rays from the top of the object strike the 
lower part of the retina, and vice versa, but the mind refers 
them to the place from which they came; hence they appear 
upright, as they really are. 
3. Accommodation. — In the camera obscura, in order to get 
a distinct picture the distance between lens and screen must 
change when the distance between object and lens changes. 
The same result could be produced without changing the dis- 
tances if a lens of different degree of convexity, or of different 
refractive power, could be substituted. The eye has not the 
power of changing the relative positions of lens and retina, but 
it has the power of changing the convexity of its principal lens, 
the crystalline lens. When a near object is observed, the lens 
becomes more convex than when a distant object is viewed. 
The mechanical arrangement for this adjustment is a perfect one 
as to results, but one difficult to understand. Helmholtz explains 
it as follows: The capsule of the lens is naturally drawn tight 
by the elastic rigidity of the sclerotic coat and presses on the 
lens, slightly flattening it. This is the passive condition, as when 
looking at very distant objects or when the eyes are closed. 
When the fibers of the ciliary muscle contract they pull the 
outer part of the capsule of the lens in toward its center. 
This relaxes the tension in the central part and permits the 
lens to swell out and become more convex. The normal eye 
when passive is adjusted to objects at an infinite distance. By 
increasing the convexity of the lens the eye becomes adjustable 186 
LESSONS IN PHYSIOLOGY. 
to all distances up to within five inches, which is the limit. It 
is at comparatively short distances only that the change is 
great. Beyond twenty feet the change is exceedingly slight. 
Thus by this beautiful mechanical contrivance we are enabled 
to see distinctly in a space varying from five inches to millions 
of miles. 
4. Regulating the Light. — The eye has been termed the 
“ window of the soul.” This window has a beautiful curtain 
which is delicately adjustable so as to admit more or less light as 
needed to form the picture on the retina. Hang a mirror by 
the side of a door. Darken the room and as you look in the 
mirror open the door to admit light. You may see the pupil of 
the eye at first quite large, then as the light becomes stronger 
it becomes smaller, and if the light be very bright it gets very 
much smaller. In some animals, as the cat and owl, the range 
of contraction and expansion of the pupil is much greater than 
in man, enabling these animals to see after night when the 
amount of light is very small. 
The iris is contracted and the pupil lessened : 
1. When the light is increased. 
2. When accommodation is made for near objects. 
3. When the eyeball is turned inward. 
4. When the aqueous humor is deficient in quantity. 
5. Under the influence of certain poisons, as opium, and in 
the early stages of alcohol and chloroform poisoning. 
The iris is relaxed and the pupil enlarged: 
1. When the light is diminished. 
2. When accommodation is made for distant objects. 
3. When there is an excess of aqueous humor. 
4. During difficult breathing, violent muscular exertion, and 
strong emotions. 
5. Under the influence of poisons, as Atropa belladonna, and 
in later stages of poisoning by chloroform. (See Lesson 35, 
Sec. 7.) 
5. Correction of Chromatism. — In images by an ordinary lens 
the outlines are edged with rainbow hues. This detracts from 
the picture. The cause lies in the fact that a ray of light com PHENOMENA OF VISION. 
187 
sists of many colors combined, the mixture producing the im- 
pression of white light, but the lens acts partially as a prism 
and refracts some colors more than others, and thus separates 
them. The optician corrects this by making his lens of two 
pieces of glass of different refractive power, one in the form of 
a convex lens, the other in the form of a plano-concave lens, 
so that the convexity predominates over the concavity and the 
compound lens is convex. In this way one part of the lens 
separates the colors and the other corrects it, and the whole 
lens is achromatic, that is, produces no color. Now the lens of 
the eye consists of three parts of different shapes and different 
refractive powers and is perfectly achromatic, or in other words, 
chromatism is corrected by a mechanical arrangement. 
6. Correction of Aberration. — Another defect in ordinary 
lenses is aberration or imperfect convergence of the rays of light, 
producing a blurred picture. It is due 
to the fact that the outer part of the lens 
refracts more than the central portion. 
This is partially overcome by using a 
diaphragm, that is, a plate with a hole in 
it, to shut off the rays coming through 
the outer part of the lens. In the eye 
the iris acts as this diaphragm. But a 
more effectual way is to make the central 
position of the lens more refractive. 
This can be done in two ways, by in- 
creasing its curvature, or by increasing 
its density. Art has not succeeded by 
the latter method, but nature does, for in the eye the crystalline 
lens is more dense in the central than in the outer portions, and 
the picture made by it is perfectly clear and distinct. 
7. Single and Double Vision. — If we press the eye to one side 
by the finger we see objects as double when both eyes are open, 
but if the eye not pressed upon be closed we see the objects as 
single. If we hold up a finger of each hand, one about a foot 
in front of the other, and direct our attention to the near one, 
the far one appears double; then, if we direct attention to the 
Fig. 28. — Compound Lens 
for Correction of 
Chromatism. 188 
LESSONS IN PHYSIOLOGY. 
far one, the near one appears double. Also if we hold up a 
finger and look at the wall beyond it, we see two images of the 
finger. If we shut the right eye the left-hand image disappears, 
and if we shut the left eye the right-hand image disappears. 
Each eye forms its own image, and when these images fall on 
corresponding places on the retina they are translated to the 
mind as one image. When one eyeball is pushed to a side the 
places of the images do not correspond, and the appearance of 
two images is the result. When our attention is directed to 
one point the two eyes are turned so that the two images are 
projected into space to the same spot and are superimposed and 
coincide with each other, hut images of other objects nearer or 
farther away are projected to different spots and their images 
do not coincide. Usually we do not give any attention to these 
secondary images. With some persons the experiments here 
given are a failure, they not being able to see the double image. 
A man frequently sees double under the influence of alcohol, 
because he cannot control the muscles which direct the line of 
vision. 
8. Irradiation. — A white spot on a dark ground appears larger 
than it really is, and a dark spot on a white ground appears 
smaller than it really is. For the same reason a person dressed 
in white appears larger than when dressed in black. This is 
because the stronger light reflected from the white objects pro- 
duces an effect on the retina beyond the outlines of its image, 
that is, the image seems to be spread out on the retina from the 
greater stimulus of the strong light. 
9. After-images. — If we look at the sun and then shut the 
eyes we can see the image of the sun for several seconds. Look- 
ing intently at a window from within a room we can shut our 
eyes and see an outline picture of the window sash and panes. 
A stick with fire on the end appears as a ring of light when 
rapidly moved in a circle. A wheel with spokes appears as a 
solid wheel when rapidly revolving. A spinning top painted in 
bands with complementary colors appears white from the min- 
gling of the colors. All of these phenomena are due to the 
foct that the impression on the retina continues for a little PHENOMENA OF VISION. 
189 
time, that is, the sensation lasts longer than the stimulus that 
caused it. 
After looking steadily at a white patch on a black ground for 
some time, if the eye be turned to a white ground a gray patch 
will be seen. After looking at a black patch on a white ground, 
if the eye be turned to a gray ground a white patch will be 
seen. This is the result of exhaustion of the retina; the part 
which received the stimulus becomes tired and ceases to respond 
for some little time to the stimulus. These are called negative 
after-images. 
10. The Yellow Spot and the Blind Spot. — We can see with per- 
fect distinctness onty one point of an object at a time. The line 
of vision must move along the printed line as we read, being 
fixed successively upon each letter of each word. By practice 
we are enabled to recognize whole words, and even lines of a 
dozen words at one glance, but to get an exact and distinct pic- 
ture of each letter the eye must be fixed upon each in succession. 
This fixing the eye on one point at a time is simply bringing it 
in such a position that the image of that point falls on the yel- 
low spot, the only point where vision is completely perfect. 
By a simple experiment we can prove the existence of a blind 
spot on the retina. (See Lesson 35, Sec. 8.) Hold this book 
on a level with the eye at the distance of a foot. Close the left 
eye and fix the right steadily on the left hand letter A. Then 
A 
A 
gradually move the book toward your face. When at a certain 
distance — about six inches — the right hand A will disappear, 
to reappear when the book is brought still closer to the face. 
Similarly the left A will disappear if the gaze be directed to the 
right A. The letter disappears because its image is thus made 
to fall on a spot incapable of receiving an impression, that is, 
the blind spot, or the place where the optic nerve enters. The 
image of an object does not fall on the blind spots of both eyes 
at the same time, hence it cuts no figure in ordinary vision. 
11. Phosphenes. — If the optic nerve be irritated in any way 190 
LESSONS IN PHYSIOLOGY. 
no pain is felt, but a sensation of light is experienced. Thus a 
blow on the head produces sometimes by the jarring this sensa- 
tion, and we call it “ seeing stars.” It is not real light, as no 
one else can see it, hut simply a sensation the same as would be 
provoked by light. If we press with the finger upon the inner 
side of the closed eye a ring of light the size of the end of the 
finger will he seen. In this case the retina is irritated by the 
pressure transmitted through the eyelid and sclerotic coat. 
These rings of light have been called phosphenes. 
12. Muscae Yolitantes. — We sometimes observe indistinct 
motes or threads floating about apparently in the sky or on the 
wall. They are due to specks of opaque matter in the trans- 
parent vitreous humor. The mind projects the images of these 
specks out into space. They are called muscse volitantes 
(“ flying flies ”). 
13. Myopy, or Near-sightedness. — The normal eye can adjust 
itself perfectly for all distances beyond five inches. In those 
persons whom we call near-sighted the refractive power of the 
lens in a passive condition is too great and the focus for distant 
objects is not on the retina, but in front of it. Such eyes have a 
very small range — from two to six inches, or from four inches 
to three feet, according to the degree of myopy. The results of 
this defect are easily overcome by wearing concave glasses which 
throw the focus back to the retina in the passive state, and then 
adjustment for near objects becomes possible. 
14. Hypermetropy, or Ear-sightedness. — This is the opposite of 
myopy. The lens in this case has not sufficient refractive 
power, and the focus lies behind the retina in the passive state. 
When young the hypermetropic eye usually sees well at a dis- 
tance, but not near at hand, because a very slight adjustment 
only is necessary to adapt the eye to long distances, but as the 
eye grows older it loses the power of adjustment, and even dis- 
tant objects cannot be seen distinctly. Such persons should 
wear convex glasses. When they grow older they need an 
extra pair with less convexity for distant objects. 
15. Presbyopy, or Old-sightedness. — This is usually regarded as 
the reverse of myopy, but, according to Le Conte, it is not. PHENOMENA OF VISION. 
191 
The presbyopic eye is perfectly normal for distant objects, that 
is, in a passive state, but it has not the power to adjust itself 
for near objects, probably from the loss of elasticity of the crys- 
talline lens. Such eyes are corrected by the use of convex 
glasses, not to be worn habitually, but for near objects, as in 
reading. Presbyopy is a functional defect, a loss of power to 
use the instrument. Myopy is a structural defect, a defect of 
the instrument itself. Myopic persons should use glasses habit- 
ually. They may continue to wear glasses of the same curva- 
ture until advanced age. Presbyopic persons usually do not 
become so before middle age. 
16. Astigmatism. — A perfect eye has its horizontal and verti- 
cal diameters equal. But some eyes have one or the other of 
these diameters greater, and the rays of light instead of being 
brought to a focus in a point are focused in a line. Such eyes 
cannot distinguish horizontal and vertical lines with the same 
readiness. Most persons have a slight degree of astigmatism, 
without themselves being aware of it. 
17. Color Blindness. — Persons vary much in their power of 
distinguishing colors. Some regard as the same, colors which 
to others are very distinct. Such persons are said to be color 
blind, or are afflicted with “ Daltonism,” so named because 
Dalton, the distinguished chemist, was so afflicted. It was 
said that Dalton could not distinguish a red gown lying on 
the green grass, or red cherries among the green leaves, except 
by their form. The inability to distinguish between red and 
green is the most usual form of it, but there are cases which 
cannot distinguish between blue, brown, and other colors. 
18. Cataract. — This is a not uncommon disease of the eye, 
producing partial or total blindness, which can be cured by a 
surgical operation. It consists of an opacity of the crystalline 
lens. The operation is nothing more nor less than removing 
the lens by cutting through the coats of the eye. The aqueous 
humor is thus lost, but will be restored. The loss in refractive 
power of the eye is compensated for by wearing convex glasses. 
In some cases the glasses are not needed, as the humors of the 
eye become more dense and sight is restored. 192 
LESSONS IN PHYSIOLOGY. 
PRACTICAL ILLUSTRATIONS. 
1. The pinhole camera described in the foregoing lesson may be made in 
another way which is very simple. Make a pinhole in the crown of a stiff hat 
and fix a piece of greased paper over the mouth of the hat. Now throw a shawl 
or cloth over your head and shoulders so as to shut out all light except what can 
come through the pinhole, and direct the crown of the hat toward some strongly 
illuminated object, as a tree, house or church spire in the sunshine. You will 
see a picture of the object on the greased paper. 
2. The principle of the camera with a lens may be shown with any pocket 
magnifying lens or burning glass, or even with a pair of ordinary spectacles. 
Hold the glass between a white wall or piece of paper and a lamp, or a window. 
By moving the lens back and forth you will find the proper place where it will 
throw an inverted image of the flame of the lamp or of the window on the screen. 
By using a piece of white paper for a screen, and a lamp for the object, you will 
have the three essentials of a camera all movable, and by changing the positions 
of each you will discover that it is only at certain relative distances that you can 
get a distinct image. By substituting a lens of greater or less magnifying power 
you can show the necessity of changing the position of the screen, of the object, 
or of the lens, that is, that a change in the convexity of the lens is the same as 
a change in the relative distance of object, lens, and screen. By having some 
person to stand in front of the window you can make the picture more striking, 
as you will see the outlines of his figure inverted. The brightness of the picture 
will be heightened if the room be darkened. 
3. Try the experiment mentioned in Section 4 of the preceding lesson. Ob- 
serve the eyes of cats and owls in the bright light, then throw a shadow on 
them and observe the change. 
4. Look through a common magnifying glass at some object as you hold it 
against the sky. You will observe a border of colors. Chromatism is not cor- 
rected in an ordinary lens. When you look into a good compound microscope 
you see no color on the image not belonging to the object. The best instru- 
ments have achromatic lenses. 
5. Try all the experiments mentioned in Section 7 of the lesso... They are 
simple but instructive. 
6. Cut out a square or circular piece of white paper and another of black 
paper exactly the same size. Paste the white one on a piece of black paper and 
the black one on a piece of white paper, and ask a friend to tell you which is 
the larger. He will invariably say the white piece is the larger. Prove him 
wrong by measuring with a rule. 
7. Try the experiments described in Section 9. Modify the spinning top 
experiment as follows. Cut out a word or phrase printed in large plain letters 
from an advertisement. Cut it in two equal parts lengthwise with the line, that 
is, so that one piece will contain the upper half of each letter and the other 
piece will contain the lower half. Paste these pieces on opposite sides of a 
card, so that the top of one half will come even with the bottom of the other 
half, letter for letter. Now fasten a string in each end of the card and give it THE STRUCTURE OF THE EAR. 
193 
a rapid rotary motion on its long axis by twisting the string. The whole word 
will plainly appear as the card revolves, the impression of one half of the letters 
remaining on the retina until the other half comes into view. The picture of a 
man, dog, horse, etc., may be cut in two and the halves arranged in a similar 
manner. An amusing form of the experiment is to draw on one side of the 
card the picture of a horse, and on the other the picture of a man in the position 
of one on horseback. The revolving card will show the picture of a man on 
horseback. 
8. Every member of the class should try the “blind spot” experiment. See 
Section 10. Also the after-images and phosplienes should be demonstrated by 
each individual. 
LESSON 37. 
The Structure of the Ear. 
1. The External Ear. — The ear is usually described as con- 
sisting of three parts: the external, middle, and internal ear. 
The external ear consists of the pinna and the auditory canal. 
The pinna is that portion which projects from the head and is 
commonly called “ the ear,” but which is not an essential part, 
as a man can hear quite well if it be cut off. It is composed of 
cartilage covered with a thin skin. The outer projecting 
rim is the helix. In front of this is a second ridge, called the 
antihelix. The depression in the center is the concha. Between 
the helix and antihelix is a furrow, the fossa of the helix. The 
antihelix divides in its upper part, and the furrow thus formed 
is called the fossa of the antihelix. Projecting backward over 
the concha is the tragus, and opposite to it is the antitragus. 
The pendulous portion of the ear is called the lobule. 
2. The Auditory Canal, or meatus auditorius externus, is a tube 
leading to the middle ear. The outer portion is membrano- 
cartilaginous, the inner portion is osseous, formed by the mas- 
toid portion of the temporal bone. It is lined with a thin 
skin continuous with that of the external ear. In the inner 
portion are the ceruminous glands which secrete the ear wax. 
The outer portion contains sebaceous glands and hairs. 194 
LESSONS IN PHYSIOLOGY. 
3. The Muscles of the Ear. — In man there are three muscles 
on the side of the head and attached to the ear. They are 
functionless, except in some rare cases, and said to be rudi- 
Fig. 29. — Sectional View of the Ear. 
a, Pinna; b, Semicircular canals; c, Auditory canal; e, Bones of the ear; f, Cochlea; 
g, Tympanic membrane; i, Eustachian tube; k, Tympanum. 
mentary, that is, in an undeveloped condition. In lower ani- 
mals these muscles are particularly active. 
4. The Middle Ear, or Tympanum. — This is an irregular 
cavity in the petrous portion of the temporal bone, and lined 
with mucous membrane continuous with that of the pharynx, 
through the Eustachian tube which joins the two cavities. Its 
outer wall is formed by the tympanic membrane, a thin, semi- 
transparent, oval partition which completely separates the mid- 
dle from the external ear. Some animals have no external ear, 
and this membrane is on a level with the surface of the body, 
or nearly so. On the posterior wall of the tympanum are 
several orifices which open into small cavities in the bone, 
called the mastoid cells. In the internal wall are two small 
openings in the bone, but covered by the mucous membrane, 
the fenestra ovalis (oval window) and fenestra rotunda (round 
window). They communicate with the labyrinth, or internal 
ear. THE STRUCTURE OF THE EAR. 
195 
5. The Bones of the Ear. — Extending from the tympanic 
membrane to the fenestra ovalis, across the cavity of the tym- 
panum, is a chain of minute bones (ossicles'), three in number. 
The malleus (hammer) is attached by its long projection (han- 
dle) to the tympanic membrane and 
by its large part, or head, to the roof 
of the tympanum and to the incus. 
Two tiny muscles are fastened to 
projections of the malleus ; one 
renders the membrane tense, the 
other relaxes it. The incus (anvil) 
has a body and two projections, one 
of which is attached to the back 
wall of the tympanum, the other 
to the stapes. The stapes (stirrup) 
extends from the incus to the fenes- 
tra ovalis, into which it fits. These 
bones are exceedingly small, yet each one is articulated to the 
others by ligaments, cartilage, and synovial membrane the same 
as other bones in the body, and all are covered with a con- 
tinuation of the mucous membrane which lines the tympanum. 
They are so attached to each other and to the walls of the 
tympanum as to form a series of levers easily moved and 
communicating motion from the external to the internal ear. 
6. The Labyrinth. — The internal 
ear, or labyrinth, consists (1) of a 
cavity in the bone of very irregular 
shape, called the bony labyrinth, 
and (2) a membraneous sac filled 
with fluid and floating in a fluid 
within it. The bony labyrinth con- 
sists of three parts, the vestibule, 
the semicircular canals, and the cochlea. 
7. The Vestibule. — This chamber serves as a means of com- 
munication between the tympanum and the semicircular canals 
and the cochlea. On the internal wall are minute openings, 
through which branches of the auditory nerve pass. In the 
Fig. 30. — Bones of the Ear. 
M, Malleus; I, Incus ; S, Stapes. 
Enlarged. 
Fig. 31. — The Labyrinth. 196 
LESSONS IN PHYSIOLOGY. 
back wall are five openings leading to the semicircular canals. 
The fenestra ovalis in the bony vestibule opens into the tym- 
panum. In the front wall is an aperture leading to the cochlea. 
8. The Semicircular Canals. — These are peculiar channels, 
three in number, in the form of loops which branch off from the 
vestibule. The superior and posterior canals stand in a vertical 
position and at right angles to each other. The third is placed 
horizontally and at right angles to the other two. 
9. The Cochlea, so named from its resemblance to a snail-shell, 
consists of a central axis, or modiolus, around which is a spiral 
canal, making two and a half turns and terminating at the apex 
in an expansion called the infundibulum. The spiral canal is 
divided into two portions by a partition partly bony and partly 
membraneous. The auditory nerve filaments pass along the 
modiolus and spread upon the partition, finally terminating in 
the organ of Corti, which consists of rows of cells in the form of 
rods or pillars, called the rods of Corti. There are about 2000 
of these minute bodies. 
10. The Membraneous Labyrinth. — The bony labyrinth already 
described is lined throughout with a serous membrane which 
secretes a fluid, the perilymph. Floating in this is a completely 
closed sac of membrane containing a fluid, the endolymph. This 
sac fills the semicircular canals, and is of the same form. The 
portion which is contained in the vestibule consists of an expan- 
sion called the utricle, and a smaller expansion called the saccule. 
In the walls of the vestibular portion of the sac are two calcare- 
ous bodies called otoliths (ear-stones). The membraneous laby- 
rinth fills only the duct or entrance to the cochlea. Portions of 
the auditory nerve ramify on the membraneous sac in the vesti- 
bule and semicircular canals. 
PRACTICAL ILLUSTRATIONS. 
1. Some idea of the tympanum and its membrane may be formed by a rough 
dissection of the ear of a cat or dog. The bone may be sawn or broken with a 
chisel sufficiently to expose the cavity of the tympanum. The little bones of 
the ear may be seen, and it is possible to get some idea of the cochlea or semi- 
circular canals by breaking open the portion of bone nearer the center of the PHENOMENA OF HEAPING. 
197 
head. The parts are all so small and so well protected by strong bone that any- 
thing like a perfect idea is difficult to get by dissection. 
2. From the interior of the skull the foramen which admits the auditory 
nerve to the internal ear may he seen near the apex of the petrous portion of 
the temporal hone. 
LESSON 38. 
Phenomena of Hearing. 
1. Sound is a vibration, or wave-motion of matter, which is 
capable of producing a special sensation through the auditory 
nerve. Usually the vibration is conveyed from objects to the 
ear through the air, but air is not essential to sound. Lay a 
watch on the forehead and you can hear the ticking distinctly. 
Move it an inch away from the head and although it be nearer 
the ear than before the ticking is scarcely audible. The sound- 
waves are conveyed to the internal ear through the bones of the 
head. But as sound-vibrations pass with difficulty from air to 
solids and liquids, a special apparatus is needed to transfer the 
vibrations to the fluid of the internal ear, where it may influence 
the terminations of the auditory nerve. This special apparatus 
is the external and middle ear. 
2. Functions of the External Ear. — The concha serves to catch 
and concentrate the waves of sound and transmit them to the 
auditory canal, which conveys them to the tympanic membrane. 
In man the concha serves but little purpose, but in many of the 
lower animals it is very important. 
3. The Use of the Tympanic Membrane. — It is a property of 
stretched membranes to vibrate easily by atmospheric waves. 
The tympanic membrane readily responds to very slight vibra- 
tions in the atmosphere. These vibrations it transmits to the 
chain of bones attached to its inner surface. The tenser tym- 
pani muscle serves to regulate the tension of the membrane 
and prevents it being pushed too far out. Some persons can 
at will produce a peculiar cracking noise in their ears. This is 198 
LESSONS IN PHYSIOLOGY. 
supposed to be due to the contraction of this muscle. The tym- 
panic membrane is exactly analogous to the diaphragm in an 
acoustic telephone, which vibrates by impulses of air and com- 
municates these impulses to the wire or string attached to it. 
4. The Eustachian Tube serves an important purpose. It is 
well known that if the air be removed from a cavity the pressure 
on the outside of its walls will be great. The air at sea level 
presses with a force of fifteen pounds to the square inch of sur- 
face. As we ascend above sea level it becomes less and increases 
as we go below sea level. The cavity of the tympanum contains 
air. If there were no means of communication with the outside 
air there would be a variation in its comparative density every 
time we changed our level and a consequent pressure either in 
or out upon the tympanic membrane. The Eustachian tube 
permits air to pass from the pharynx to the tympanum, and thus 
keeps the air on both sides of the membrane in equilibrium. 
When loud sounds are produced the violent impulse of air 
against the tympanic membrane is somewhat relieved by the 
Eustachian tube acting as a valve to permit some of the air to 
pass out of the tympanum. In this respect it acts like the hole 
in the side of a drum. When cannon are fired, if a person 
stands on tiptoe, so that the body will be swayed by the air- 
wave, and holds the mouth open so that air will escape through 
the Eustachian tube, the danger of rupture of the tympanic 
membrane is very much lessened. 
5. The Function of the Ossicles. — The bones of the ear are so 
placed as to act as a series of levers multiplying the force of 
the vibration of the tympanic membrane, and every movement 
of this membrane is by them transmitted with increased power 
to the perilymph through the fenestra ovalis. 
6. The Functions of the Vestibule. — It is believed that the 
branches of the auditory nerve, which spread in the mem- 
braneous labyrinth in the vestibule, are capable of transmitting 
the sensation of noise simply, and cannot translate musical 
sounds or distinguish pitch and quality of sounds. The oto- 
liths are supposed by some to intensify the vibrations, by others 
to act as dampers of the sound. PHENOMENA OF HEARING. 
199 
7. The Semicircular Canals have, it is believed, a function some- 
what aside from hearing. When the vertical canal was destroyed 
in a pigeon the bird continued to move its head up and down, 
and when the horizontal canal was destroyed it moved its head 
from side to side. When a person is made to rotate rapidly 
dizziness and inability to stand erect is the result. These facts 
seem to point to the conclusion that in some way the semicir- 
cular canals are concerned in maintaining the upright position 
of the body, probably by sending impulses to the brain which 
inform it of the body’s relation to surrounding objects. This 
question is involved in much obscurity. 
8. The Cochlea is the most important part of the internal ear. 
Here, doubtless, the distinction between sounds of different 
pitch, quality, and intensity is made by sympathetic vibrations 
of the rods of Corti, communicated to them by the perilymph. 
We may say that the cochlea hears music and differentiates 
sounds, and the vestibule simply conveys the sensation of sound 
in general. 
9. Auditory Sensations. — Sound, as before stated, is a vibration 
capable of affecting the auditory nerve. This vibration usually 
starts by the setting in motion of some object, this motion being 
communicated to the air as a wave which passes into the audi- 
tory canal, shakes the tympanic membrane, which in turn shakes 
the chain of bones, the last one of which, as it pushes the mem- 
brane across the fenestra ovalis, produces a wave-motion in the 
perilymph, part of which is conveyed to the endolymph of the 
vestibule and semicircular canals, and part passes to the cochlea 
and affects the organ of Corti. The effect of the vibration on 
the nerve endings in the cochlea and vestibule is to produce 
nervous impulses, which pass along the auditory nerve to the 
brain, where they give rise to the auditory sensation. These 
sensations may be classed as noises and musical sounds. A noise 
is an irregular sound, or one without periodicity. A musical 
sound is one which occurs and recurs at regular intervals. There 
are, however, all grades between these two. 
In both musical sound and noise we recognize loudness or 
intensity. This is determined by the amplitude of the vibration, 200 
LESSONS IN PHYSIOLOGY. 
in other words, by the amount of matter set in vibration. In 
musical sounds we recognize: (1) pitch, which is determined by 
the rapidity of the vibrations. The more rapid they follow in 
succession, the higher the pitch. (2) Quality, or timbre. This 
is due to the sounds being not simple, but compound vibrations. 
A body vibrates as a whole, also in parts. The vibrations of the 
parts are either slightly higher or slightly lower in pitch, and 
these “over-tones” and “under-tones,” mingling in varying 
proportion with the “ fundamental tone,” produces the different 
qualities of different sounds. 
In order to produce a sensation of sound, the vibrations of a 
body must have a certain degree of rapidity. If less than about 
sixteen vibrations per second no sound is heard. If over 38,000 
vibrations per second no ear can hear a sound. These limits 
vary, however, in different individuals. It has been conjectured 
that there are sounds in nature, which are heard by insects and 
not by the human ear, that these animals may be able to commu- 
nicate with each other by sounds inaudible to the human being. 
10. Auditory Judgments. — The auditory sensation is always 
referred to the external world, that is, projected into space, just 
as visual sensations are. The judgment of distance of sounds 
is very imperfect. A loud sound with high pitch seems far 
away, and a faint sound with low pitch seems near. This is 
the secret of the ventriloquist, who, by adroitly varying his 
tones and calling attention by words or gestures to distant, or 
near objects, succeeds in making his hearers believe that the 
words come from different persons in different places. 
11. The Audiphone. — Defects in hearing are sometimes reme- 
died by using an instrument by which advantage is taken of the 
fact that the bones of the head will convey vibrations. The 
instrument is placed in contact with the teeth, and is so arranged 
as to vibrate by receiving the wave-motion from the air. In 
case of injury or destruction of the tympanic membrane this 
instrument is useful. 
12. In ordinary subjects there is no direct communication 
between the auditory canal and the tympanum, but we occa- 
sionally see a person who can take tobacco smoke into his PHENOMENA OF HEAliING. 
201 
mouth and cause it to come out at his ears. Such persons have 
a perforated tympanic membrane. A slight perforation may 
not materially interfere with hearing. 
13. The Ear-wax. — This is a peculiar, sticky, and very bitter 
substance, which is for the purpose of keeping out dust and 
insects. The dust is caught and adheres to the outer layer of 
the wax, which on exposure to the air hardens and falls off in 
scales, and thus the ear is self-cleaning. The insects are repelled 
by the bitter and adhesive nature of the wax. 
PRACTICAL ILLUSTRATIONS. 
]. Lay a watch on the table. Hold a stick or a ruler a foot or more in length 
with one end on the watch and the other between the teeth. The ticking of the 
watch will be distinctly heard although it may not he otherwise when at the 
same distance. This illustrates the fact that the air is not necessary to the pro- 
duction of sound. 
2. Make an acoustic telephone thus: Take two old tin cans. Melt or cut out 
the bottoms. Tie over the end of each a piece of strong paper tightly stretched. 
Pass a string through this paper diaphragm on one can, securing it on the inside 
by a knot. This string may he forty of fifty feet long, and the other end passed 
through the paper of the other can and secured in the same manner. In using 
the string should not come in contact with anything solid. Let one person hold 
the open end of one can to his mouth and speak into it while another holds the 
other can to his ear. A conversation may thus be carried on at a distance. In 
a rough way we may liken the paper diaphragm of one can to the tympanic 
membrane, the string to the chain of hones, and the other diaphragm to the 
perilymph of the internal ear, and the person hearing the words to the nerve- 
terminations. The vibration of one diaphragm is communicated to the string 
and thus to the other diaphragm, and this again to the air, causing waves exactly 
similar to the waves started by the voice of the person at the other end. 
3. Shout or sing a syllable loudly into an open piano. A sound of the same 
pitch will be heard coming from the strings. The vibrations of air of your voice 
has set a string vibrating, and its vibration is given to the air again. It will be 
found that the only string of the piano which vibrated is that one which is 
capable of producing a sound of the same pitch as your voice. Such vibrations 
are called sympathetic vibrations. The rods of Corti have been supposed to 
vibrate in sympathy with the different sounds and thus the different notes are 
distinguished by the brain. 
4. The Eustachian tube opens when an effort is made to swallow and a little 
air passes up into the tympanum. This may be proven by closing the nostrils 
and making an effort to swallow. A peculiar sensation is felt in the ear, caused 
by the air entering the tympanum. 
6. Take a walking-stick in both hands, place one end on the floor, and turn 202 
LESSONS IN PHYSIOLOGY. 
round rapidly four or five times ; then quickly aim with the point of the stick at 
a point on the wall three or four feet distant. The whirling motion will have so 
disturbed the brain, probably through the semicircular canals, that it will be 
next to impossible to touch the point aimed at. 
LESSON 39. 
Smell, Taste, and Touch 
1. The Nasal Fossae.— These are two irregular cavities in 
the nose. The openings in front are called anterior nares, or 
nostrils, and the openings into the pharynx behind, the posterior 
nares. The interior contains a great deal of surface caused 
by the irregular nature of the inferior turbinated bone and 
the superior maxillary. The septum between the fossae is 
formed mainly by the vomer and a triangular piece of cartilage. 
The interior is lined with a continuation of the mucous mem- 
brane of the pharynx and here called the Schneiderian membrane. 
That portion of it in which is distributed the filaments of the 
olfactory nerve is much thicker, contains more blood-vessels, 
and many brown pigment cells. The remaining portion con- 
tains ciliated epithelium. Numerous mucous glands are dis- 
tributed throughout the membrane. 
2. The Olfactory Nerve arises from three roots in the cere- 
brum which unite in a cord ending in a bulb-like expansion, 
called the olfactory ganglion. This bulb lies on the upper 
surface of the ethmoid bone and from it branch off about 
twenty nerve-filaments which pass through holes in this bone 
and thus reach the Schneiderian membrane. The nerve-fila- 
ments terminate in long, delicate threads with a number of 
expansions in their course; these threads are called the olfac- 
tory cells. 
3. The Sensation of Smell. — Odorous particles of matter in 
the inspired air passing through the nasal fossae affect the ter- 
minations of the olfactory nerve and give rise to the sensation 
of smell. The odorous particles must be in a gaseous medium, SMELL, TASTE, AND TOUCH. 
203 
as is shown by the experiment of filling the nasal fossae with 
rosewater or other perfumed liquid, when no odor is perceived. 
As with sight and hearing we project the sensation into the 
external world. The smell does not seem to be in the nose 
but somewhere in the air outside of it. 
4. The Organs of Taste. — The mucous membrane covering 
the upper surface of the tongue, the back part of the mouth, 
the soft palate and uvula, and possibly a portion of the upper 
part of the pharynx, contains the nerve-endings which give rise 
to the sense of taste. 
5. The tongue is the principal part concerned in taste. It is 
composed of several sets of muscular fibers, the whole covered 
with mucous membrane. On the upper surface are a number 
of little elevations called papillae, which give the tongue its 
characteristic roughened appearance. These papillae are of two 
kinds, simple and compound. The simple papillae are similar 
to those of the skin. The compound papillae are of three kinds : 
(1) The circumvallate are the largest, about eight or ten in 
number, forming a Y-shaped row at back of the tongue. (2) 
The fungiform papillae are mostly on the tip and edges of the 
tongue. They are smaller and ovoid in shape. (3) The fili- 
form papillae are the most numerous, covering the whole sur- 
face of the front and middle parts of the tongue. They are 
small, and conical in shape. The epidermis covering them is 
in the form of hair-like processes having a general inclination 
backward. In many animals these processes are large and 
horny and serve as hooks to help securing food. In animals of the 
cat kind they form a rasp which is used in removing the flesh, 
which forms their food, from the bones. The filiform papillae 
are supposed to act as organs of touch rather than taste. 
6. The “Taste Buds.” — According to some authorities the 
nerves of taste terminate in flask-shaped organs which are called 
“taste buds,” or “gustatory bulbs.” They are found principally 
in the circumvallate papillae, and less numerous in the fungi 
form. (See Lesson 31, Sec. 2, Table of Cranial Nerves.) 
7. We recognize several distinct tastes as sweet, sour, bitter, 
salty, and pungent or peppery. The latter is probably not a 204 
LESSONS IN PHYSIOLOGY. 
real taste-sensation, but an effect on the nerves of general sen- 
sation similar to that produced by heat. Bitter substances pro- 
duce the greatest sensation when placed on the back part of the 
tongue, and sweet substances on the tip of the tongue. Sour 
substances are said to be most effectual on the edges of the 
tongue. No substance can be tasted unless it is in a liquid form 
or capable of solution in the saliva. Syrup of sugar tastes 
sweeter than the crystalline sugar, because more readily soluble 
in the secretions of the mouth. 
8. The Sense of Touch. — If you place the palm or surface of 
your fingers on a substance of any kind at the ordinary temper- 
ature, you can tell by the contact of the fingers alone whether 
it be solid or liquid, hard or soft, smooth or rough, and can gain 
a fairly good conception of its shape. This knowledge can be 
obtained, but in a much smaller degree, by contact with any 
other part of the skin and even by the tongue and mucous mem- 
brane of the mouth. 
9. The Sensation of Temperature. — The skin is capable within 
certain limits of giving sensations which vary with the tempera- 
ture, and we recognize them as warm or hot, cool or cold. 
Intense heat and intense cold produce the sensation of pain 
only. A good conductor of heat, when colder than the skin, 
feels colder than a poor conductor of the same temperature 
because it rapidly abstracts the heat from the skin. A good 
conductor, when warmer than the skin, feels warmer than a poor 
one of the same temperature, because it imparts its own heat to 
the skin. Thus a piece of silver, unless it be of the same tem- 
perature as the body, always feels either warmer or cooler than 
a piece of wood of the same temperature. 
10. The Muscular Sense. — When we press our hands on an 
object we are sensible of the amount of pressure we exert, but 
when we hold an object in our hand and lift it up and down we 
are conscious, not only of the pressure of the object on the hand, 
but also of the amount of muscular exertion required to hold it 
up. We are thus enabled to form a judgment of the weight of 
the object. This is called the muscular sense, and by some lias 
been regarded as a sixth sense, co-ordinate with sight, hearing, 
taste, smell, and touch. SMELL, TASTE, AND TOUCH. 
205 
11. The Sensations of Hunger and Thirst, and of Fatigue. — These 
are distinct sensations, but are difficult to locate. In extreme 
hunger there is a painful sensation in the stomach, and in great 
thirst the mouth and throat are the seats of disagreeable sensa- 
tions. Fatigue may be of the mind or of the body, or of some 
particular part of the body. 
12. General Sensation. — The sensations of temperature, of 
weight and pressure, of hunger and thirst, of fatigue and pain, 
and some others that we can scarcely designate with a name, 
may all be grouped together as general sensations produced by 
stimulation of the terminations of the nerves of common sensa- 
tion, which are distributed throughout the whole body, but are 
most numerous in the skin. There are but few sensory nerve- 
fibers in the body of large muscles, as is shown by the compara- 
tive absence of pain when they are cut. Boys sometimes drive 
a pin its entire length into the thigh. After passing through 
the skin there is scarcely any pain. In the days before anaes- 
thetics were used, those who submitted to amputations of limbs 
said they suffered very little or no pain when the knife was 
passing through the muscles. 
The stimulation of the trunk of a nerve of general sensation 
gives rise to a sensation of pain at the extremity of the nerve. 
Thus if we press on the ulnar nerve where it lies near the skin 
at the point of the elbow, we feel a painful sensation in the third 
and little fingers where this nerve is distributed. Sensations 
started in the stump of an amputated limb are referred to the 
absent member. (See Lesson 3, Sec. 1.) 
13. The Special Sense of Touch seems to reside mainly in the 
palmar surface of the fingers. In the papillary layer of the 
corium certain bodies have been described as the terminations 
of the nerves. These are called tactile corpuscles and are sup- 
posed to be the special organs of touch. 
PRACTICAL ILLUSTRATIONS. 
1. The sense of taste and of smell are sometimes confused. To test this tell 
some person to shut his eyes, open his mouth, and close his nostrils, and having 
previously, and unknown to the person, procured a small piece of onion, place 
it in his mouth and ask him to eat it and tell you what it is. The probability 206 
LESSONS IN PHYSIOLOGY. 
is that he will be unable to tell until his nose is relieved and he gets the odor. 
We smell an onion and imagine we taste it. 
2. Judgments formed by the sense of touch alone may be misleading, as is 
shown by an experiment familiar to many and said to be as old as Aristotle. 
It is this: Shut the eyes and cross the fore and middle fingers, and place between 
them a small round object, as a pea or a bullet, so that it will come in contact 
with the radial side of the forefinger and the ulnar side of the middle finger. 
We will seem to be touching two objects instead of one. 
LESSON 40. 
Hygiene of the Special Sense-Organs. 
1. The Eye is a very delicate and sensitive organ, easily ir- 
ritated by any foreign body or substance, as dust, smoke, or 
irritating gases. The delicately adjusted parts are easily strained 
and wearied by improper use. Hence an avoidance of all irri- 
tating substances and excessive and improper use of them is of 
great importance. 
2. When a foreign object gets into the eye do not rub it, for 
this only causes greater irritation. By a strong effort of the 
will you may keep from winking for several seconds, during 
which time the tears will accumulate in quantity sufficient often 
to wash out the offending body. If this fails, close the nostril 
on the opposite side and blow the nose forcibly. This may 
create a suction in the nasal duct which will draw the object to 
the inner corner of the eye. If these means fail, let some one 
roll the eyelid over a pencil and look for the object. If found, 
remove by touching with the twisted corner of a handkerchief. 
3. Use no medicine or salve for the eyes without the advice 
of a physician. You may do more harm than good. Bathing 
the eye in cool or tepid water can do no harm, and is often bet- 
ter than any medicine to allay irritation from any cause. 
4. The light in reading, sewing, or other work requiring 
special exercise of the eye, should not fall on the eye, but 
on the work. Do not sit facing the light, but so that it will 
come over the left shoulder; then it will not shine in the eyes, HYGIENE OF THE SPECIAL SENSE-ORGANS. 
207 
but on the work, and no shadows will interfere. Artificial light 
is hard on the eyes unless it be bright and steady. It may be 
too bright, as the electric arc light. A very bright lamp mel- 
lowed by a porcelain shade is perhaps the best. 
5. Small type, poor printing, and paper of an ashen gray or 
dirty tint are frequent causes of diseased eyes. So is reading or 
sewing in the twilight, or by a poor artificial light. Reading in 
a jolting car or carriage is also injurious if indulged in to any 
great extent. Reading in a recumbent position is not advisable. 
In all these cases the eyes are put on a strain, and they soon 
become tired and finally weak from exhaustion. 
6. Perhaps the most frequent cause of weak eyes is the con- 
stant use of them upon objects at the same distance. Every two 
or three minutes the eyes should be rested by looking for a few 
seconds at some distant object. This gives rest to the muscle 
concerned in accommodation. Remember that when looking at 
a distant object the eye is in a passive condition, or at rest, and 
that it is put on a strain when looking at near objects. 
7. The eyes are often weak when recovering from a spell of 
sickness. This is especially the case in convalescence from 
eruptive diseases, as measles, small-pox, and scarlet fever. The 
utmost care should be then taken or the eyes may be permanently 
injured. 
8. Never purchase spectacles from a pedlar or ordinary dealer 
in them. Go to an oculist and let him examine your eyes and 
select the proper glasses for you, and don’t postpone it too long. 
9. Cigarette smoking is said to be injurious to the eyes. To- 
bacco smoke can certainly do the eyes no good, and the bad effect 
of tobacco on the nervous system of some persons may be mani- 
fested in the form of weak eyes. 
10. The eyes of the drunkard are bloodshot and bleared from 
the excessive blood pressure in the capillaries, caused by the 
alcohol affecting the circulatory system. 
11. The Ear is perhaps not so easily injured as the eye, but 
it is important to observe certain rules of hygiene bearing on 
this organ. 
12. Very loud sounds, as the firing of cannon, may cause rup- 208 
LESSONS IN PHYSIOLOGY. 
ture of the tympanic membrane. The danger is lessened, as 
has been elsewhere noted, by standing on tiptoe and keeping 
the mouth open. 
13. The ear-wax should not be removed with an ear spoon or 
other instrument unless unnatural in quantity or nature. The 
finger will penetrate the auditory canal far enough for ordinary 
cleansing purposes. A wet cloth over the finger’s end is usually 
sufficient to keep the ear clean. Never pick the ear with a pin, 
knitting needle, or anything of the kind. You may let go of the 
pin, or some one may accidentally jostle your arm and cause the 
instrument to penetrate the tympanum. 
14. The ear should be protected from cold winds, but not by 
compact material, such as ear-muffs are made of. Ear-muffs keep 
the ear too warm, and make it more sensitive to the cold when 
they happen to be left off on going out. A very little cotton 
placed in the ear is a good thing when riding in the cold wind, 
or a shawl thrown loosely over the head to break the force of 
the wind. 
15. If a child gets a small object, as a pea, bean, or cherry 
stone, into the ear, do not make frantic efforts to extract it. 
The auditory canal is wider at the inner end, and an object 
pushed far in is very difficult to extract. First, turn the ear 
down and tap gently on the other side of the head. If this 
does not dislodge it, use a syringe and a little warm water, 
keeping that side of the head down. If this fail, send for a 
physician and do not permit any one to touch the object until 
he arrives. Cherry stones have been known to remain in the ear 
for years without serious results, so do not become alarmed. 
16. If an insect gets into the ear, pour in a little oil of any 
kind. This will kill the insect and not injure the ear. A 
syringe and warm water will then generally remove the dead 
insect. 
17. Throwing snowballs is dangerous sport. Permanent 
deafness has been caused by snow being forcibly driven into 
the ear. 
18. In ascending or descending a mountain it is necessary to 
make frequent efforts to swallow, as this permits air to pass up HYGIENE OF THE SPECIAL SENSE-ORGANS. 
209 
the Eustachian tube and maintains the equal pressure on both 
sides of the tympanic membrane. 
19. Very highly seasoned and very hot foods and drink tem- 
porarily blunt the sense of taste, and possibly have a permanent 
injurious effect on the nerves of taste. 
EXERCISES FOR REVIEW. 
1. What bones form mainly the orbits of the eye ? 
2. What is the conjunctiva ? Can you see it ? 
3. What are the parts of the outer tunic of the eye ? 
4. Are there any nerves in the sclerotic coat ? In the cornea ? 
5. What is the condition know as a “ blood shot ” eye ? 
6. What gives the choroid membrane its dark color ? What is its color in 
albinos ? 
7. Where is the “ color of the eyes ” ? 
8. What relation does the pupil of the eye bear to light ? 
9. What are the terminations of the optic nerve called ? Where are optical 
elements the most numerous ? 
10. Which is the thinnest of the humors of the eye ? 
11. What is the use of the lachrymal fluid ? When is it called “ tears ” ? 
12. What kind of an optical instrument is the eye ? 
13. Explain accommodations. When is the eye at rest ? 
14. What use is the iris besides regulating the amount of light ? 
15. Explain why the eye is a perfect optical instrument. 
16. When do we see double ? 
17. Why do persons look larger dressed in white than when they are dressed 
in dark clothes ? 
18. What is the blind spot ? Phosphenes ? 
19. What kind of glasses should a myopic person use ? A presbyopic ? A 
hypermetropic ? 
20. Why does a plus sign look like a minus sign to some persons ? See Sec- 
tion 16, Lesson 36. 
21. What is the matter with a person who cannot tell green from red ? 
22. How may cataract be cured ? 
23. The use of the bones of the ear. 
24. What are the semicircular canals ? Their use ? 
25. What separates the endolymph from the perilymph ? 
26. Otoliths ? Organ of Corti ? 
27. What is sound ? Is air necessary for the producing of sound ? 
28. What is the use of the Eustachian tube ? 
29. Classify sounds. Name the properties of sound. 
30. Explain the “throwing the voice” by the ventriloquist. 
31. The audiphone. What does it prove ? 210 
LESSONS IN PHYSIOLOGY. 
32. How does the olfactory nerve reach the nasal cavity ? What is the 
Schneiderian membrane ? 
33. What is taste ? Where is it located ? 
34. What is the muscular sense ? 
35. Do you taste or smell an onion ? 
36. What should be the position of the light in reading or writing ? 
37. How should one take care of the ear ? 
HINTS TO TEACHERS. 
The different parts of the human body are so closely related that the anatomy 
and physiology of no one part can be clearly understood until the other parts 
have been studied. In this respect this study differs from some others in which 
the different branches are more or less independent. From this fact it is evident 
that frequent reference from one part of the work to another is necessary, and 
frequent reviews, in which the relations the different systems sustain to each 
other are discussed, should be given. 
The pupil should constantly be urged to make frequent use of the index of 
the book, and to compare one part with another. Occasional lessons, consisting 
of a given number of questions, to answer which the pupil will be obliged to 
search the entire book, should be assigned. He will then be compelled to use 
the index, and thus become accustomed to the true method of study in general, 
which is to use books- as means of acquiring knowledge, not as so many pages to 
be “gone over.” Part IV. 
GENERAL INFORMATION ON FOODS AND STIM- 
ULANTS. 
CHAPTER I. 
HOW TO SELECT PROPER FOODS AND DRINKS. 
■H 
LESSON 41. 
Heat-making Foods. 
1. In Lesson 15 we gave a classification of foods as to com- 
position and nutritive value. We would advise the pupil before 
beginning the study of this lesson to read that lesson again. 
2. Wheat. — This is the most important vegetable production 
of temperate climates. It is an almost perfect food, as it con- 
tains a large per cent of tissue-making material, although the 
greater part of its weight and bulk is starch, which is a heat- 
making food. The outer layer of a grain of wheat is largely 
silica, a substance destitute of nutriment. This is separated 
with the coarsest bran. Next to this is a layer of aleurone 
grains, so called by the botanist, but usually called gluten from 
its adhesive properties. This is highly nitrogenous and there- 
fore tissue-making. The main part of the kernel is almost pure 
starch. In ordinary white flour a large part of the gluten goes 
with the starch. It is what makes the bread spongy when 
raised by the escape of gases in baking. A great deal has been 
written about the value of graham flour, or whole wheat flour; 
but most writers overlook the fact that the stimulating effect of 212 
LESSONS IN PHYSIOLOGY. 
the coarse bran causes the food to pass on too rapidly in the 
stomach and intestines, and a considerable portion of the nutri- 
ment is not absorbed; so that while it contains more tissue- 
making ingredients than white flour, the system does not appro- 
priate as much of it. Graham bread and cracked wheat are 
valuable for the variety they afford rather than for their in- 
trinsic merits. 
Macaroni, which forms the chief food of the people of South- 
ern Italy, and is used to a considerable extent in this country, 
is made from the finest wheat flour, formed into a paste and 
dried. Vermicelli, much used in soups, is similarly made. They 
are richer in nitrogenous material than our white bread, as the 
wheat of Italy and Southern Russia, from which these articles 
are made, contains more gluten than our wheat. 
3. Corn, or maize, contains eleven per cent nitrogenous matter, 
sixty-four of starch, eight of fat, and a little sugar. It is, taken 
altogether, a valuable heat-making food. It is liable to be irri- 
tating to the intestines of some persons. It should be used 
more in winter than in summer. Green ears of corn, or “ roast- 
ing ears,” are palatable and wholesome if well cooked. Corn- 
starch, used frequently in puddings and other dishes, is almost 
pure starch. 
4. Oatmeal contains about fifty-eight per cent of starch, twelve 
of nitrogenous matter, five of sugar, five of fat, and is a valu- 
able food material. It should be thoroughly cooked. 
5. Barley. — This is a valuable food, but not used to any 
great extent in this country for bread. It contains sixty-nine 
per cent of starch, four or five of sugar, and about six per cent of 
nitrogenous matter. Pearl barley is simply the grain with the 
husk removed. It is a palatable and nutritious food when well 
cooked. 
6. Bye. — This grain is not much used in this country for 
bread, although in nourishing qualities it is not much inferior to 
wheat. It contains sixty-nine per cent of starch, and eight per 
cent of nitrogenous matter, with some sugar and fat. Rye flour 
mixed with wheat flour and made into bread is palatable and 
affords a good variety. HEAT-MAKING FOODS. 
213 
7. Rice. — This grain is rich in carbonaceous, or heat-forming 
material, being about seventy-nine per cent starch, and but six 
of albuminous matter, and a small proportion of fat and sugar. 
It is easily digested, and forms a valuable addition to our food- 
stuffs. It forms almost the entire food of millions of people in 
eastern countries. 
8. Arrow-root. — Obtained from the root of a tropical plant. 
It is almost pure starch. A great many preparations are sold 
under the name of arrow-root which are simply starch prepared 
from different plants. English arrow-root, it is said, is made 
chiefly from potatoes. It is often recommended as a food for 
the sick, but as it is not palatable unless sweetened, it would be 
better to use some other substance rich in starch, and which is 
palatable in itself. 
9. Tapioca. — This substance is also nearly pure starch, and 
is prepared from the root of a tropical plant. It is often used 
in puddings and is useful in its place. 
10. Sago. — This is another form of starch produced from 
various species of palm trees. It is very similar to arrow- 
root. 
11. Potatoes. — Irish potatoes contain eighteen per cent of 
starch, two per cent of albuminous matter, three per cent of 
sugar, the remainder being mostly water. The sweet potato 
contains more sugar, but in other respects is similar. Potatoes 
should be thoroughly cooked. When boiled they should be 
put in boiling water and kept at that temperature until soft. 
Then they should be exposed to dry heat until they appear 
mealy. If roasted, the oven should be hot when put in. If 
fried, the fat should be very hot when they are put in. Other- 
wise potatoes become soggy, unpalatable, and unwholesome. 
They should not be eaten when very young nor when diseased. 
12. Buckwheat contains about eighty per cent of starch, 
and about two and a half of albuminous matter. Buckwheat 
cakes have been known to produce an eruption on the skin 
when eaten frequently. 
13. Beans and Peas. — These vegetables contain so much 
albuminous, or tissue-making material, that they might be placed 214 
LESSONS IN PHYSIOLOGY. 
in that class, blit the starch predominates, being about fifty 
per cent of the latter to twenty per cent of the former. When 
ripe and hard they should be boiled at least five hours. Beans 
are among the most economical articles of diet in use in this 
country, as they contain much nourishment (both heat-making 
and tissue-making material) in proportion to the price. 
14. Sugar. — The principal ingredient in the foods we have 
mentioned is starch. Another form of carbonaceous or heat- 
making food is sugar. It is found in most all vegetables 
and fruits to a greater or less extent. Beets contain about 
ten per cent, and are largely used in France and Germany as 
a source of sugar of commerce. Bananas contain twenty per 
cent of sugar. Cabbage, turnips, carrots, and potatoes contain a 
small per cent of sugar. Dates are nearly half sugar. All fruits 
contain some sugar. Honey is almost pure sugar. 
There are two varieties of sugar commonly used for food, 
cane sugar, or saccharose, and grape sugar, or glucose. The 
former is obtained mostly from the sugar cane, but also from 
sorghum, beets, corn stalks, maple trees, and some other 
vegetable substances. Grape sugar is found in many kinds 
of fruits, and exists along with cane sugar in maple trees, and 
in many plants it is found in small quantities. It is usually 
produced, however, by boiling starch for a long time with weak 
sulphuric acid. This process converts the starch to sugar. 
Grape sugar is largely employed as an adulterant of cane 
sugar and in the manufacture of candy and syrups. It is 
less soluble than cane sugar, and not nearly so sweet to the 
taste, but is equally valuable and wholesome as a food. 
15. Eats and Oils. — The only difference between fat and oil 
is that the former is solid and the latter liquid at ordinary 
temperatures. They are carbonaceous and mainly heat-making. 
All animal food contains more or less fat. The ordinary grains 
contain a small per cent of oil. Nuts are rich in oil. Cocoa- 
nuts form the principal food of many people in tropical coun- 
tries. The ill effects that are often ascribed to eating nuts are 
mainly because they are eaten between meals and as an addi- 
tion to, rather than a part of, the regular food. Butter is the TISSUE-MAKING FOODS. 
215 
fat of milk, and is generally regarded as more palatable than 
other forms of fat. The substitute for butter known as oleo- 
margarine is one of the triumphs of the chemist’s art. It is 
prepared from beef tallow, and that of the best grade is a 
perfect imitation in flavor of real butter, and is pronounced 
equally wholesome by good authorities. Eggs contain about 
eleven per cent of oil. 
PRACTICAL ILLUSTRATIONS. 
1. The presence of starch in any article is very easily shown even when it 
exists in minute quantities. Heat a little of the substance supposed to contain 
starch in clear water, and when cool add a few drops of tincture of iodine. The 
mixture immediately turns blue if starch be present. If in considerable quan- 
tity the color will be black. As the test is delicate, to get a beautiful blue color 
use but very little of the material to be tested in a large amount of water. 
2. If a microscope is accessible, the teacher may show the starch grains in 
potatoes, beans, or grain, by making a very thin section with a razor, or by 
scraping a minute portion from the mass, placing it on a glass slide, and adding 
a drop of water. By adding a little tincture of iodine much diluted with water, 
the grains take on a beautiful blue color. The starch grains vary much in size, 
and are of different shapes in different vegetables. 
3. If starch, flour, or corn meal be used as an adulterant of any article of food 
or condiment, its presence is easily detected by the methods above given. 
LESSON 42. 
Tissue-making Foods. 
1. The tissue-making foods are nitrogenous, or albuminous. 
Many of the articles mentioned in Lesson 41 contain a large 
per cent of tissue-making material, but the following are mainly 
of this nature. 
2. Beef. — There is no better nitrogenous food than beef. The 
lean meat contains about twenty per cent of albuminous matter, 
the remainder being water and a small amount of salts. When 
of good quality and properly cooked it is easily digested. It is 216 
LESSONS IN PHYSIOLOGY. 
usually most wholesome and palatable when fresh. It should 
never be eaten raw, as there is a possibility that it may contain 
germs which will produce tape worms or trichina. When fried 
the fat should be very hot when it is put in, as otherwise the 
meat will absorb the fat and become tough and indigestible. 
3. Pork. — Not quite so nutritious as beef and not so easily 
digested. The fibers are firmer and require a longer time to 
dissolve in the gastric juice. There is a great deal of prejudice 
against the use of pork, much of which is unfounded. If the 
animals be in a healthy condition and the meat well cooked no 
harm can result from the use of pork. It should under no cir- 
cumstances be eaten raw. Thorough cooking and thorough 
mastication are required. Ham is best when thoroughly boiled 
and eaten cold. Bacon is regarded as a luxury by the rich and 
as a necessity by the poor. Such food should be eaten in the 
morning when the digestive powers are at their highest. 
4. Mutton. — “ Although an agreeable and valuable food for all 
classes, it is not so well fitted as beef to sustain great exertion, 
but is rather a food for those of sedentary and quiet habits, 
including women and the sick.” — Dr. Edivard Smith. 
5. Poultry. — The flesh of chickens, turkeys, geese, and ducks 
is generally regarded as lighter food than beef, mutton, and 
pork. This is not because of inferior nourishing qualities, but 
rather because they have a more delicate flavor and are more 
easily digested. They contain nearly as much nutriment as 
beef. 
6. Game. — This includes all wild quadrupeds and birds used 
for food. As a rule only those animals that live on purely 
vegetable food are fit to eat. The flesh of wild animals is gen- 
erally easy of digestion and almost as nutritious as beef. 
7. Eggs. — Contain all the elements required by the body 
and in about the proper proportion, hence are a perfect food. 
When raw or soft boiled they are more easily digested than when 
boiled hard. However, when long boiled they become again 
easily digested. The proper way to cook an egg in the shell is 
to put it in boiling water and set it off of the fire, allowing it to 
remain a few minutes in the hot water. In this way the heat TISSUE-MAKING FOODS. 
217 
penetrates to the center of the yolk and the white is merely 
turned to a milky condition, which makes them more palatable 
and easy of digestion. A pound of eggs contains more nourish- 
ment than a pound of meat, hence at average prices they are 
cheaper than meat. 
8. Fish. — Fish contain much less nutriment than meat. 
Fresh fish are easily digested, and for a variety form a palatable 
addition to the list of nitrogenous foods. Fish with red meat, 
as the salmon, are more nutritious than those with white meat. 
Fish contain a larger per cent of phosphorus than the flesh 
of higher animals, and are said on that account to he good food 
for brain-workers. It must be remembered, however, that the 
human system appropriates only a certain amount of material 
in building up the tissues, and that there is probably more phos- 
phorus in ordinary meat and in the nitrogenous parts of vege- 
tables than is needed by the system. A fish diet increases the 
amount of phosphates (salts containing phosphorus) in the 
excretions, showing that only a part of the phosphorus is 
appropriated. 
9. Cheese. — This is the albuminous part of milk, the remain- 
der being water, sugar, and fat. It is strong food and does not 
agree with many persons. Fresh milk from healthy cows is a 
wholesome article, and like eggs a perfect food, as it contains the 
nitrogenous, or tissue-making elements in the caseine (cheese), 
and the carbonaceous, or heat-making, in the butter (fat) and 
sugar. 
10. Oysters and Clams. — These, and other mollusks which are 
sometimes eaten, contain a large per cent of water, hence are 
not of high nutritive value. Raw oysters are, perhaps, the most 
easily digested of all articles. This is especially true of the 
greenish or dark part (the liver) of the animal. For sick per- 
sons, or those who have weak digestive powers, they are a valu- 
able food. 
11. The quantity of heat-making food should be in excess of 
the tissue-making. The body is constantly losing heat which 
must be supplied by the consumption of fuel. This fuel comes 
indirectly as carbonaceous food. It has been computed from 218 
LESSONS IN PHYSIOLOGY. 
many careful experiments and observations, that a man doing 
ordinary work requires daily 4.59 ounces of nitrogenous and 
17.22 ounces of carbonaceous food. This means solid food. 
In addition he requires from seventy to ninety ounces of water, 
partly in the form of drink and partly as a constituent of the 
food. It will be observed that we find in nature a larger per 
cent of carbonaceous food. The supply of starch, sugar, and fat 
far exceeds that of albuminous substances. 
LESSON 43. 
Relishes and Condiments. 
1. There are many articles in our daily dietary which are 
usually classed as foods, but their nutritive value is so small that 
they may be regarded more as relishes, and as aids to digestion, 
serving to dilute the more highly nutritious foods. Many 
fruits and vegetables belong to this class, some of which will be 
noticed in this lesson. 
2. Apples. — Contain over eighty per cent water, some sugar, 
starch, and acid. They form a valuable addition to more nutri- 
tious foods. They should be well cooked or thoroughly ripe, 
and not eaten in large quantities at one time. The skin and 
seeds with their horny coverings are indigestible and should not 
be eaten. 
3. Peaches, Plums, and Apricots. — Very, wholesome, but not 
more nutritious than apples. The seeds are poisonous if eaten 
in any considerable quantity. 
4. Pears. — More nutritious than apples, but more difficult of 
digestion. 
5. Cherries. — Very wholesome and agreeable acid fruit. They 
contain from eight to thirteen per cent of sugar and a small 
amount of albuminous matter. The seeds have been known to 
lodge in the vermiform appendix and cause serious trouble. RELISHES AND CONDIMENTS. 
219 
6. Blackberries, Raspberries, and Strawberries. — Similar in com- 
position, contain sugar and acid, wholesome and agreeable to 
most persons. The seeds are indigestible, but so small that they 
do no injury. 
7. Grapes. — Contain from nine to fifteen per cent of sugar, 
about one per cent of albuminous matter, and over eighty per 
cent water, with some tartaric acid. The skins and seeds are 
indigestible. The latter have been known to lodge in the ver- 
miform appendix. They should not be eaten. When grapes 
are perfectly ripe there is no fruit more agreeable to the system. 
8. Oranges and Lemons. — Contain a large amount of citric 
acid, especially lemons. Wholesome fruits. Lemonade is one 
of the most agreeable of drinks and the least harmful. 
9. Cabbage. — Consists of ninety-four per cent water, a small 
amount of sugar and albuminous matter. Could never be used 
alone for food, as the amount of nourishment is too small. If 
not well cooked is difficult of digestion. Cauliflower and kale 
are very similar. 
10. Turnips. — Contain ninety-one per cent water, some sugar, 
and a very little nitrogenous matter. Afford a good variety as 
a relish and addition to more substantial foods. 
11. Carrots, Parsnips, and Celery. — More nutritious than cab- 
bage or turnips. Disliked by many persons. Wild parsnips 
are said to be poisonous, but it is probable that in the cases 
reported another plant was mistaken for the parsnip. 
12. Melons. — The pulp of watermelons is almost entirely 
composed of water and a little sugar. Muskmelons contain a 
little more solid matter. Melons are valuable for their cooling 
and refreshing properties. They should be perfectly ripe and 
fresh to be wholesome. 
13. Cucumbers. — Are regarded by some as very indigestible, 
but when eaten in moderate quantities do not appear to be 
injurious to healthy stomachs. 
14. Pumpkins and Squashes. — Wholesome and moderately 
nutritious. 
15. Rhubarb. — Contains much acid and cannot be used in 
great quantity. 220 
LESSONS IN PHYSIOLOGY. 
16. Gooseberries, Currants, and Cranberries. — These very 
strongly acid fruits afford a good relish, especially when eaten 
with meats. They should be used in moderation. 
17. Tomatoes. — An agreeable acid vegetable, formerly not 
supposed to be eatable, but becoming more popular every year. 
18. Onions. — Contain a stimulating oil which gives them their 
pungency and peculiar odor. In cooking this oil is largely 
evaporated. They are moderately nutritious, containing more 
nitrogenous matter than the potato but only one-fourth as 
much carbonaceous matter. 
19. “ Greens.” — This includes a great number of succulent 
vegetables which are eaten when young. Persons are often poi- 
soned by eating plants for “ greens ” which they suppose are 
harmless. Young rhubarb leaves and poke leaves are said to 
be poisonous. “ Greens ” afford but little nourishment, water 
being the principal constituent. 
20. Gelatine. — The skins of animals, the tendons and bones 
when boiled yield a substance called gelatine. When dry it forms 
glue. It is a much disputed question as to whether gelatine is 
nutritious. Dr. Whittaker says, “ Though the gastric juice will 
attack and dissolve gelatine it has very little if any nutritive prop- 
erties, and should never in any of its forms (jellies, isinglass, Ice- 
land moss) be relied upon as an article of food.” Professor Flint 
arrives at about the same conclusion. But Dr. Edward Smith 
says, “ My experiments, and those of others, have proved that 
it is a valuable food, since it increases vital action in the same 
direction, if not in the same degree, as albumen.” The “ jelly ” 
of fruits is called pectin. It is very similar to the gelatine of 
animal bodies. Much that is put on the market as fruit jelly 
is simply the gelatine of animals flavored and sweetened in 
imitation of the jelly of various fruits. Whether nutritious or 
not jellies and soups are very agreeable additions to, our dietary, 
and seem to be harmless. 
21. Mushrooms. — There are many species of fungi which may 
be eaten, but few persons are able to distinguish the wholesome 
from the poisonous kinds. Two well-known edible species 
grow quite abundantly in this country, one generally appearing RELISHES AND CONDIMENTS. 
221 
in early spring, the other late in the summer. We cannot 
enter into a description of these species here, hut will say that 
those who are not able to recognize them and do not relish 
their taste miss one of the luxuries of life. Mushrooms con- 
tain about ninety per cent water, and are therefore more to be 
regarded as a relish than as a food, although of the solid con- 
stituents nitrogenous matter forms a considerable part. 
22. Condiments. — This term includes certain substances which 
do not supply material for the growth or warmth of the body, 
but in some way not well understood render food more palatable, 
stimulate our appetite, and in some cases supply certain neces- 
sary elements to the fluids of the body. The condiments may 
be grouped as salt, vinegar, and spices. 
23. Salt. — Common salt, or chloride of sodium, has been in 
use from the earliest times. Enough, perhaps, exists naturally 
in ordinary foods for the purposes of the system, and the principal 
reason for putting an additional quantity in our food is to give 
it taste and to stimulate the salivary glands to action. Where 
there is a continued use of salted meats and the absence of fresh 
fruits and vegetables, as is sometimes the case on board vessels, 
or in armies, a disease known as scurvy appears. This disease 
is not due to the use of salt, or salty food, as some may suppose, 
but fo a deficiency of certain acids and their chemical salts, 
such acids being found in fresh vegetables and fruits. 
24. Vinegar. — This is acetic acid diluted with water and 
mixed with flavoring extracts of whatever it be made from. 
Acetic acid is a product of fermentation. By a certain kind of 
fermentative process starch is changed to sugar; by another 
fermentation sugar is changed to alcohol; and by still another 
kind of fermentation alcohol is changed to acetic acid. The 
first is called the saccharine, the second, vinous, the third, acetic 
fermentation. Any substance, then, containing starch, sugar, or 
alcohol can be used as a source of vinegar. The best vinegar is 
that made by the fermentation of fruits, as it is agreeably 
flavored by certain extracts from the fruits. Apple, or cider 
vinegar is the most commonly made in this country. A writer 
in the Popular Science Monthly says: “ The value of vinegar as 222 
LESSONS IN PHYSIOLOGY. 
a condiment depends on the fact that acetic acid dissolves gel- 
atine, fibrine, and albumen; hence it aids in digesting young 
meats, fish, lobsters, and hard-boiled eggs. The acid assists 
also in the conversion of cellulose (woody fiber) into sugar, 
which is the first stage in the digestion of green leaves used in 
salads. It is a mistake to use vinegar on beans, for it renders 
insoluble the legumen, which is their chief nutritive constit- 
uent.” 
Vinegar will cure scurvy, hence it is inferred that some acid 
of vegetable origin is lacking in the dietary which produces 
scurvy. 
25. Spices. — Spices have been held in high esteem from the 
earliest times. They are frequently mentioned in the Bible. 
It is recorded that “Neither was there any such spice as the 
Queen of Sheba gave Solomon.” One of the most commonly 
used spices is black pepper. It imparts a flavor to certain foods, 
and used in moderation is not injurious, except to sensitive 
stomachs. Red, or Cayenne pepper is from an entirely different 
species of plant, but differs but little in its effect on the system. 
Mustard is another spice in common use. It is not objection- 
able unless used in excessive quantities. Cloves, cinnamon, nut- 
megs, and allspice are aromatic spices, and milder in their action 
than the peppers and mustard. They impart delicate flavors to 
fruits. Ginger is a strong spice, more useful perhaps as a medi- 
cine than as a condiment. In its native country it is made 
when young and fresh into a delicious preserve, which is gently 
stimulating. 
LESSON 44. 
Water and Non-alcoholic Beverages. 
1. The Use of Water in the Body. — Without water there could 
be no life. Water is the transporting agent in nature. Mate- 
rial must be conveyed from one place to another in all building 
processes. Organic growth is a building process. The parts of WATER AND NON-ALCOHOLIC BEVERAGES. 
223 
a vegetable or animal body which are the most active contain 
the most water. The bones and teeth when fully grown are 
comparatively inactive and contain less water in their composi- 
tion. The muscles and nerves are active parts and are largely 
composed of water. As we learned in the introduction, fully 
three-fourths of the body is water. Dr. Edward Smith thus 
sums up the uses of water in the body: “ First, to soften and 
dissolve solid foods so as to facilitate their mastication and 
digestion; second, to maintain a due bulk of blood and the 
structures of the body; third, to keep substances in solution or 
suspension whilst moving in the body; fourth, to supply ele- 
ments in the chemical changes of the body; fifth, to enable the 
waste material to be carried away from the body; sixth, to dis- 
charge superfluous heat by transpiration through the skin, and 
by emission through other outlets; and seventh, to supply in 
convenient form heat to, or to abstract heat from, the body. 
Some of these functions are performed by water in its liquid 
state, and others in a state of vapor.” 
2. Water in the Food. — The amount of water existing natur- 
ally in food varies from five to ninty-five per cent or more. 
Sugar contains the least, only five per cent, while milk, eggs, 
lean meats of all kinds, fish, potatoes, turnips, cabbage, and 
parsnips all contain over seventy per cent. Wheat flour 
contains fifteen, and rice thirteen per cent of water. On an 
average each adult takes from twenty to thirty ounces of water 
daily in his food, and requires from seventy to one hundred 
ounces in all for the purposes of nutrition. There are wide 
ranges, however, from this average. In a warm atmosphere 
and while exercising much more water is required. Women 
drink less water than men, and children more than adults in 
proportion to their size. 
3. Composition of Water. — Pure water, that is, water simply, 
consists of two gases, hydrogen and oxygen, chemically com- 
bined in the proportion of two parts by volume of the former to 
one of the latter, or by weight two parts hydrogen to sixteen 
parts oxygen. But pure water in this sense does not exist 
except in the chemist’s laboratory. Water so readily absorbs 224 
LESSONS IN PHYSIOLOGY. 
gases and dissolves solids that as soon as exposed to the air it 
begins to acquire impurities. The question for the hygienist 
is what of these impurities are injurious and what harmless. 
The water of one section of country differs from that of 
another on account of differences of soil and rock, and differ- 
ences in the gases existing in the atmosphere. In limestone 
regions the water contains a large amount of carbonate of lime 
in solution, and we say the water is hard because it does not 
mix with soap readily and dissolve and remove dirt so easily 
as soft water, that is, water comparatively free from salts 
of lime. In sandstone regions, or where there is but little 
calcareous matter in the soil, the water is soft, but it may 
contain other minerals than carbonate of lime. Just how 
much of these inorganic salts water should have to give it 
flavor and not be injurious is a difficult question to deter- 
mine. 
4. Dangers from Unwholesome Water. — (1) Diseases of the 
alimentary canal from the irritation produced by water contain- 
ing an excess of mineral matter are recorded. These mineral sub- 
stances are sometimes dissolved in the water and again partly dis- 
solved and partly suspended. When dissolved the water is per- 
fectly clear, but will have a peculiar taste. Persons may become 
accustomed to such water when it will no longer influence 
them injuriously. When the matter is suspended, the water 
is muddy or discolored. This matter may be removed by fil- 
tering or by settling with alum and other chemicals. Dis- 
solved and suspended vegetable and animal matter may also 
produce diseases of the digestive tract. Boiling the water 
before using will remedy this. Water which has stood in lead, 
zinc, or copper vessels or pipes becomes poisoned, and injuri- 
ously affects the digestive organs. In this case the only rem- 
edy is to avoid the use of such water. 
(2) Malarial fever is supposed to be caused in some in- 
stances by use of water which has stood in contact with decay- 
ing vegetable matter, a specific poison being developed in the 
water. (3) Typhoid fever is readily communicated from one 
person to another through the excretions of the body getting WATER AND NON-ALCOHOLIC BEVERAGES. 
225 
into the drinking water. Other contagious diseases, as yellow 
fever and Asiatic cholera, are said to be propagated by means 
of contaminated water. Boiling or filtering the water does not 
destroy or remove the germs of these diseases. (4) The eggs 
and embryos of human internal parasites, as tape worms and 
other intestinal worms, are believed to be introduced into the 
body by means of water. Boiling the water will destroy these 
germs. 
5. How to Test Water. — Wholesome drinking water should 
have no decided taste nor odor, and be at least moderately 
clear. The water generally used in large cities comes from 
rivers or lakes and is frequently quite muddy looking, so much 
so that the person drinking it for the first time is inclined to 
think it very unwholesome, but the color is due to suspended 
clay and sand in a very fine state of division and is rarely inju- 
rious. But clearness is no test of wholesomeness. Water may 
be perfectly wholesome, especially to those accustomed to its 
use, when it is almost black with sediment, and on the other 
hand may be as clear and sparkling as a drop of dew and yet be 
loaded with deadly germs and wholly unfit for use. The senses, 
then, are not to be trusted in selecting wholesome water. There 
is no easy way to test for the presence of germs of contagious 
diseases, but we can always know whether the excretions from 
persons diseased can possibly contaminate the water we use. 
Water from wells near vaults or open sewers or graveyards, is 
liable to be contaminated and should be avoided. The percola- 
tion of the water through the earth does not remove all impuri- 
ties, as is sometimes supposed. 
Water containing a large amount of dissolved animal or vege- 
table matter is injurious. This cannot be detected by the senses, 
as it may be clear and have no disagreeable taste. But if let 
stand in a vessel for a day or two in a warm place it will acquire 
a decided foul odor. This is a rough test. A more delicate one 
is as follows: Get the druggist to dissolve a few grains of per- 
manganate of potassium in an ounce of distilled water. Add 
enough of this solution to a tumblerful of the water to give it 
a decided pink tinge. A few drops will be sufficient. If 226 
LESSONS IN PHYSIOLOGY. 
organic matter be present this pink color will fade out in a few 
hours. If the water be free from organic matter the color will 
remain. 
6. Non-alcoholic Drinks. — There are a number of drinks which 
are harmless in any reasonable quantities that may be substi- 
tuted for water. In hot weather such drinks are usually bene- 
ficial and for occasional use to be preferred to water. There is 
no drink, however, which may not be used in excessive quanti- 
ties and prove injurious to the digestive organs. 
7. Buttermilk. — This is peculiarly grateful to many persons 
in hot weather. It is slightly nutritious and rarely does harm. 
8. Lemonade. — There is no drink, perhaps, less liable to be 
injurious than this. It should, however, be drunk slowly and 
be made only moderately cold. If the ice be grated or pounded 
fine it may be made exceedingly cold and thus prove injurious 
by rapidly lowering the temperature of the body. 
9. Unfermented Cider. — The juice of apples contains no alco- 
hol until it has begun to taste “sharp,” and shows numerous 
minute bubbles when held to the light. Then fermentation 
has begun and alcohol is being manufactured from the sugar 
which it contains. Cider may be kept from fermenting by boil- 
ing a certain time, or by the addition of ground mustard. Boil- 
ing changes its flavor and makes it disagreeable to many persons. 
Sweet or unfermented cider is a wholesome drink when used in 
moderation. 
10. “ Soda Water.” — This is a very inappropriate name, as it 
contains no soda nor any compound of sodium, nor is soda used 
in its manufacture. It consists of water in which a large 
amount of carbonic acid gas has been forced under pressure. 
When it is drawn from the fountain it mixes with the syrup 
previously placed in the glass. This syrup is a solution of 
sugar containing certain flavoring extracts. Sometimes these 
flavoring extracts are made from fruits, again they are made 
from a class of substances called “ ethers,” which are obtained 
from coal tar. In any case they are not injurious and the only 
harm that may usually come from drinking soda water is from 
the excessive coldness of the mixture. The carbonic acid gas WATER AND NON-ALCOHOLIC BEVERAGES. 
227 
rapidly escapes as you drink, and gives a peculiarly agreeable 
sensation in the stomach and mouth. 
11. “ Ginger Ale.” — This is not strictly a non-alcoholic drink, 
as it contains, usually at least, a very small per cent of alcohol, 
so small, however, that ft can scarcely be said to produce any 
physiological effect. The drink is gently stimulating from the 
ginger and sometimes peculiarly grateful to the stomach in hot 
weather. “ Sarsaparilla,” “ phos-ferrone,” “ orange phosphate,” 
and many other special drinks are prepared and sold alongside 
of soda water and lemonade. They ma}1- all be classed with 
ginger ale as comparatively harmless beverages. 
12. Warm and Hot Drinks. — The use of some kind of warm 
or hot drink is almost universal, some races and nations prefer- 
ring one kind and some another exclusively, others using a 
variety of them. The United States contains more persons 
who are exclusive cold water drinkers than any other country 
in the world. In Europe and Asia many people would sooner 
think of going without food than without their accustomed 
beverage. The substances most commonly used in the form of 
warm or hot drinks are Chinese tea, Paraguay tea, Abyssinian 
tea, coffee, cocoa (chocolate), and chicory. 
13. Chinese Tea. — The tea plant is a small shrub and is 
chiefly cultivated in China and Japan. It has probably been in 
use in China for 1200 years. It was introduced into England 
in the seventeenth century. In 1678 a book on tea was pub- 
lished in England which described it as “ the infallible cause of 
health,” and recommended it as a cure for every disease. The 
writer thought that 200 cups a day would not be excess. At 
present more than 600,000,000 people use tea. Green tea 
differs from black only in the mode of preparation, both kinds 
being made from the same plant. More tea is consumed in 
northern than in southern countries. The Russians are great 
tea drinkers. The active ingredients of tea are a volatile oil, 
theine, and tannic acid. The combination of these three pro- 
duce the peculiar effects of tea on the system. Tea is turned 
black by the addition of any substance containing iron in a 
soluble state. This explains why brown sugar and molasses 228 
LESSONS IN PHYSIOLOGY. 
blacken the tea. The iron forms ink by combining with the 
tannic acid. Tea should be steeped, not boiled, as the volatile 
oil is driven off in boiling. 
Paraguay tea is the leaves of a species of holly growing in 
South America. It is much more powerful than Chinese tea 
and is in use in South America by 10,000,000 people. Abyssin- 
ian tea is a substitute for Chinese tea and is used to a great 
extent in Asia. When the leaves are fresh it is very intoxicat- 
ing. 
14. Coffee. — Coffee is the seed of a tree growing in tropical 
countries. Although it does not resemble tea in taste, its 
chemical composition and physiological effects are very similar. 
Coffee is in use in almost every country in the world, but is 
more extensively used in southern countries. Coffee should be 
both boiled and steeped, or what is better, although not always 
practicable, made by raising it to a temperature above the boil- 
ing point in a closed vessel without permitting it to boil. 
15. Cocoa. — This is the seed of a tropical or semi-tropical 
tree. Chocolate is prepared from the cocoa beans by grinding 
and mixing it with sugar, and forming into cakes. Chocolate 
is one of the safest of the mild drinks. It seems to have peculiar 
sustaining properties whose effects are not followed by depres- 
sion. It is in use by at least 200,000,000 people. The reason 
many persons do not like it is because they make it too strong, 
the peculiar oil which it contains making it disagreeable to 
those not accustomed to it. It contains an appreciable amount 
of nutriment in the form of oil and gluten. 
16. Chicory, or Succory. — This is a substitute for coffee which 
is largely used by poor people in many parts of the world. It is 
the root of a plant found growing wild in the United States, from 
New England to Iowa. It is cultivated extensively in Europe 
for the sake of the root. It has a bitterish taste, but none of 
the pleasant aroma of coffee. It contains an oil which has 
similar properties to tea and coffee. It is often used to adul- 
terate coffee. It may be detected by putting the ground mix- 
ture in cold water. The chicory gives color to the water while 
the coffee does not. WATER AND NON-ALCOHOLIC BEVERAGES. 
229 
17. As we have stated in former lessons, a moderate use of 
these mild drinks, as tea, coffee, and chocolate, is not injurious 
to the majority of adults, and in old age are in many cases 
positively beneficial. One should not become a slave to them. 
A proper exercise of reason and judgment in their use and a use 
of our will power in abstaining from them when we are convinced 
that they are doing us injury, is possible with all persons who 
have arrived at mature age. Children should not be permitted 
to use them. Milk and water are proper drinks for the grow- 
ing period of life. It should be a part of school instruction and 
training that all drinks of the nature of tea, coffee, and choco- 
late, and all alcoholic drinks, and tobacco, are dangerous arti- 
cles during the period of growth. 
EXERCISES FOR REVIEW. 
1. Read carefully Lesson 15 and compare it with Lessons 41 and 42. 
2. Why is wheat a valuable food ? 
3. What part of the wheat kernel contains heat-making food ? 
4. On what does the food value of macaroni depend ? 
5. Why should potatoes be cooked rapidly ? Because the walls of the cells 
which contain the starch burst and the potatoes are made dry, mealy, and the 
saliva and gastric juice can more readily penetrate and act upon the nutritious 
portions. When put in cold water or slowly cooked, the cell walls absorb water 
and are stretched without bursting. 
6. Why are beans economical as food ? In what respect do they resemble 
animal food ? 
7. Glucose ? What kind of sugar is found in beets ? In maple trees ? 
8. To what class of foods do fats and oils belong ? 
9. What is the test for starch ? 
10. Compare beef and pork as to nutritive value ; as to digestibility. 
11. Why are eggs perfect food ? 
12. What element is characteristic of the flesh of fishes ? 
13. Caseine ? Its value as a nutriment ? 
14. What class of foods is required in greatest quantity ? 
15. Why are fruits valuable additions to more substantial food ? 
16. What is gelatine ? Its food value ? 
17. What are condiments ? Compare Lesson 43, sec. 22, with Lesson 16, 
sec. 10. CHAPTER II. 
DANGERS OF STIMULANTS AND NARCOTICS. 
LESSON 45. 
Alcohol. 
1. Origin and Composition. — Alcohol does not exist in nature, 
except in very minute quantities in some natural waters, where 
it is doubtless formed from fermentation of the sugar of vege- 
table matter. It is a result of a destructive process we call 
fermentation. Common alcohol comes from sugar, and all 
sugar from starch, which is a special product of growing plants. 
The vinous fermentation, or that chemical change whereby 
sugar is split up into alcohol and carbon dioxide, is the result 
of a growing plant of a low order, generally known as the 
yeast plant. Under the proper conditions of temperature and 
moisture, the germs of the yeast plant grow and reproduce 
themselves, and in some way are the cause of the decomposition 
of the sugar. Sugar consists of a certain proportion of carbon, 
hydrogen, and and alcohol consists of another propor- 
tion of the same elements. There are several varieties of alco- 
hol known to the chemist, but only one, ethyl alcohol, is used 
as a beverage. Any substance containing sugar may be a 
source of alcohol; also any substance containing starch, since 
starch can be converted into sugar. 
2. Uses in the Arts and Medicine. — Alcohol is a most useful 
substance in a great many arts. It burns without smoke, 
making a very hot flame, and is used by artisans in a variety of 
ways. It is a solvent for resins and other substances which are 
insoluble in water, thus making it useful in varnishes and paints. 
It hardens and preserves tissues, and is indispensable in the ALCOHOL. 
231 
study of the minute structure of plants and animals. In medi- 
cine its uses are numerous. The properties of many plants 
could never be extracted without the use of alcohol. It is used 
in dissolving out and separating the medicinal properties of 
plants in many cases where the alcohol itself forms no part of 
the finished product. To sum up, the researches of the scientist 
and the work of the artisan would be set back hundreds of years 
were the world to be deprived of alcohol. 
3. Action on Vegetable and Animal Substances. — Alcohol 
hardens and preserves all animal and vegetable tissues. It pre- 
serves by abstracting the water and destroying the germs of 
putrefaction. It hardens by abstracting water and coagulating 
albumen. Add a little alcohol to the white of an egg and 
observe that it turns it white and solidifies it at once. 
4. Summary of its Physiological Effects. — In the foregoing 
pages we have had much to say of the physiological effects of 
alcohol. It is proper here to make a summary of these effects. 
1. On the Osseous System. — No direct effect, only through the 
digestive and circulatory systems, whereby the nutrition of bone 
is affected. This is shown in stunting and checking growth 
when given to children. 
2. On the Muscular System. — Impairs the functions of the 
muscles, destroying their power of co-ordination. Of course, 
this is brought about by its action on the nerve-centers which 
control muscular action. This is shown in the unsteady gait, 
the want of precision of touch, the double vision and “ thick 
tongue ” of the inebriate. 
3. On the Digestive System. — Abstracts water from the mu- 
cous membrane, inflames and thickens it, lessening its sensibility, 
thus diminishing power of absorption; weakens the blood-ves- 
sels of the stomach by distending them; hardens the liver and 
causes disease of this and other glandular organs. 
4. On the Circulatory System. — Weakens the circulatory 
organs by overworking them and distending them. 
5. On the Respiratory System. — Engorges the capillaries of 
the lungs and mucous membrane of respiratory tract, thus dimin- 
ishing the power of oxygenating the blood and increasing the 
tendency to disease of these parts. 232 
LESSONS IN PHYSIOLOGY. 
6. On the Secretory System. — Affects all glands, overworking 
them at first, hardening them afterward. By sending the blood 
to the surface causes rapid loss of the heat of the body. 
7. On the Nervous System. — Impairs the power of all nerve- 
centers properly to control the various organs. Hardens the 
albuminous constituents of nerve-tissue and leads to insanity. 
8. On the Special Sense- Organs. — By its effects on the nervous 
system it must necessarily affect injuriously all special sense- 
functions. 
Dr. N. S. Davis, in a paper read before the International Con- 
gress, July 14, 1891, thus sums up the effects of alcohol: — 
By all chemists, and other scientific men, it is classed as an active poison capa- 
ble of speedily destroying life when taken in sufficient doses ; and if taken pure 
or undiluted, it destroys the vitality of the tissues with which it comes in con- 
tact as readily as creosote or pure carbolic acid. When largely diluted with 
water, as it is in all the varieties of fermented and distilled liquids, and taken 
into the stomach, it is rapidly imbibed or taken up by the capillary vessels and 
carried into the venous blood, without having undergone any digestion or change 
in the stomach. With the blood it is carried to every part, and made to pene- 
trate every tissue of the living body, where it has been detected by proper chemi- 
cal tests as unchanged alcohol, until it has been removed through the natural 
process of elimination, or lost its identity by molecular combination with the 
albuminous elements of the blood and tissues for which it has a strong affinity. 
The most varied and painstaking experiments of chemists and physiologists, 
both in this country and Europe, have shown conclusively that the presence 
of alcohol in the blood diminishes the amount of oxygen taken up through the 
air-cells of the lungs, retards the molecular or metabolic changes of both nutri- 
tion and waste throughout the whole system, and diminishes the sensibility and 
action of nervous structures, in direct proportion to the quantity of the alcohol 
present. By its strong affinity for water and albumen, with which it readily 
unites in all proportions, it so alters the hemaglobin of the blood as to lessen 
its power to take the oxygen from the air-cells of the lungs, and carry it as 
oxyhemaglobin to all the tissues of the body; and by the same affinity it 
retards all atomic or molecular changes in the muscular, secretory, and nervous 
structures ; and in the same ratio it diminishes the elimination of carbon- 
dioxide, urea, phosphates, heat, and nerve-force. In other words, its presence 
diminishes all the physical phenomena of life. 
5. Social and Moral Effects. — In a community where the drink- 
ing habits have full sway, the social and moral condition of the 
people is of a low grade. Drunken men are generally quarrel- 
some, and fights and murders are common where there is no ALCOHOL. 
233 
check upon this vice. A love of drink, and its attendant sports 
and amusements, excludes higher and more intellectual amuse- 
ments and occupations. It is true we occasionally see a man 
of genius who at the same time is a “hale fellow well met,” 
and who frequently succumbs to the effects of alcoholic bever- 
ages, but such cases are to be pitied and not admired. Robert 
Burns and Edgar A. Poe will always be pitied in the same 
breath that expresses admiration of their works. 
Alcohol, moreover, actually blunts the moral sense, by its 
effects on the brain-tissue. Many a man has committed crime 
under the influence of alcohol who would have been under 
other circumstances only moderately immoral. We may all 
recall instances in our own experience of fathers and husbands 
who, when sober, are kind and affectionate to their families, 
but under the influence of liquor are transformed into demons 
whose very presence is dreaded. It is curious to note that 
there are some cases where a man is more generous and affec- 
tionate when drunk than when sober. Very few confirmed 
drunkards really reform. They may sign a pledge of total 
abstinence, exhort and lecture others to reform, and then in 
spite of all efforts of friends and relatives resort again to their 
cups, having no moral strength to control their appetite for 
drink. This should be a lesson to those who are yet on the 
safe side, a warning to reform before they have gone too far, 
and an argument for total abstinence to those who have never 
begun. 
6. Temperance Reform. — This is not the proper place to dis- 
cuss methods of temperance reform. Men honestly differ as 
to the means of checking the horrid vice of intemperance, but 
a word as to the prospects of the temperance cause, and a 
hint regarding the part the teachers and pupils of our public 
schools may play in the work of reform will not be out of 
place. 
We are safe in saying that more has been done in the United 
States towards checking intemperance than in any other country 
in the world. This does not mean that our people are more 
temperate than other nations. It seems to be an universal rule 234 
LESSONS IN PHYSIOLOGY. 
that the people of cold and dry climates are, other things being 
equal, more inclined to intemperance in the use of alcohol than 
those of warm and moist climates. There is more drunkenness 
in Russia than in any other country in the world. Sweden, 
Norway, and Scotland are also notorious for the drinking habits 
of the people. On the other hand, in Italy and Greece there 
is very little drunkenness, although almost every individual, 
from the child in the cradle to the tottering gray-beard, drinks 
mild wines which contain very little alcohol. The people of 
the United States have a strong natural tendency to drink 
alcoholic liquors to excess, but this tendency is held in check 
by the moral and intellectual force of the people. There are 
more total abstainers from all kinds of intoxicants in this 
country than anywhere else, and this is due largely to the 
work of temperance societies, temperance lecturers, and the 
influences of teachers, ministers, and the public press. We 
have made intemperance unfashionable to a great degree, and 
confined it to the lower strata of society. This is not so much 
the case in other countries. 
Whatever may be done in other ways, one thing is certain, 
that a more general diffusion of a knowledge of physiology and 
the effects of alcohol on the system, and a knowledge of its real 
nature, will do much towards temperance reform. Every school 
boy and girl who studies physiology can contribute something 
towards this reform. A love of knowledge in general will also 
contribute much towards the desired end; for the young person 
who loves to read and takes delight in acquiring knowledge, 
whether of science, history, language, or literature, will care 
little for the so-called pleasures of indulging the appetite. 
LESSON 46. 
Alcoholic Beverages. 
1. Fermented Liquors. — In a proper sense all alcoholic liquors 
are fermented liquors, that is, the alcohol which they contain ALCOHOLIC BEVERAGES. 
235 
is produced by fermentation; but what is here meant by fer- 
mented liquors are those which at first consist of water, sugar 
(or starch), and flavoring substances, and subject to conditions 
under which the sugar is converted to alcohol (or the starch to 
sugar and this sugar to alcohol), and the whole used as a drink 
without further change, except it may be the addition of other 
flavoring substances or narcotic drugs. Fermented liquors may 
be again divided into two classes, the beers and the wines. 
2. The Beers. — Beers differ from wines chiefly in containing 
a small amount of nutritious material; contain a bitter or nar- 
cotic substance, usually hops ; are fermented by the addition of 
yeast, and do not contain acids except sometimes, as in the case 
of sour beer, acetic acid. Ordinary beer is prepared from barley 
somewhat as follows: the barley is first moistened with water 
and placed where it is warm enough to cause it to germinate. 
At a certain stage the germination is stopped by heat. This 
substance is called malt. The germination of the seed pro- 
duces a substance called diastase, which has the power of convert- 
ing starch to sugar; the malt is then bruised, or ground, and 
mixed with water. The water dissolves the sugar already 
formed by the action of the diastase, and the latter goes on to 
convert the balance of the starch to sugar. The liquid thus 
formed is called the wort. The wort is then boiled, which kills 
the diastase and stops its action. Yeast is next added to the 
liquid, and the vinous fermentation begins, and the sugar is 
changed to alcohol. Before all of the sugar is converted into 
alcohol the liquid is put into strong kegs and kept from the air 
and in a cool place, otherwise the beer would sour, or the vinous 
fermentation would be completed and followed by the acetous 
fermentation. The sparkle and foam of beer is due to the car- 
bonic acid gas, which is always produced in vinous fermentation. 
The bitter taste of the beer is given by the addition of hops, 
which contain a narcotic principle and add to the intoxicating 
properties of the liquor. Beers contain from three to eight per 
cent of alcohol, and are among the mild alcoholic beverages. 
Other grains are used for making beer, but barley is the prin- 
cipal one in this country. In South America chica, or maize 236 
LESSONS IN PHYSIOLOGY. 
beer, is made from Indian corn, and is a common drink among 
the natives. In the valleys of the Sierra it is made in a pecu- 
liar way. A description of the process is given here because of 
its bearing on a physiological fact. The natives gather around 
a large vessel and each one chews corn and throws the pulp into 
the vessel. The mass thus obtained is mixed with water and 
allowed to ferment. Can the student of physiology guess what 
converts the starch to sugar in this case ? It is the ferment, 
ptyalin, of the saliva. 
Quass, or rye beer, is a favorite drink in Russia, and Bouza, 
or millet beer, in Tartary. Koumiss, or milk beer, made from 
mare’s milk which is peculiarly rich in sugar, is also largely 
used in Tartary. Saki, or rice beer, is used largely in Japan 
and other eastern countries. Ale and porter are modified beers. 
3. The Danger in Beer. — Immense quantities of beer are 
consumed in the United States. It does more harm here than 
in European countries, first, because of the more sensitive 
nature of the nervous systems of Americans it produces more 
effect, and second, because our customs of drinking are differ- 
ent. In Europe men and women will sit down at a table and 
sip their beer slowly while they chat, and it is largely used with 
their food also. Here it is the custom for two or more persons 
to “treat” each other, and each one drinks in rapid succes- 
sion one glass after another, and excess is thus much sooner 
reached. Besides, the beer made in this country usually con- 
tains more alcohol and hops than that of other countries. 
Is beer nourishing ? The amount of nutriment in it is so 
small that it is not worth considering. Liebig, the great Ger- 
man chemist, said, “ If a man drinks daily eight or ten quarts of 
the best Bavarian beer, in the course of twelve months he will 
have taken into his system the nutritive constituents contained 
in a five-pound loaf of bread.” Think of a man drinking over 
twenty barrels of beer in order to get as much nourishment 
as he would from five ordinary loaves of bread. 
The use of beer leads to stronger alcoholic drinks. Many a 
drunkard began as a boy to drink an occasional glass of beer 
which he was told would not hurt him. ALCOHOLIC BEVERAGES. 
237 
4. The Wines. — Wines differ from beers chiefly in their con- 
taining less nutritious matter, in being free from narcotic in- 
gredients other than alcohol, in being fermented without the 
addition of yeast, and in containing various acids belonging to 
the fruits from which they are usually made. The general 
method of making wine is to expose the juice of fruits or vege- 
tables to air in a warm place until it has reached a proper 
degree of fermentation, when it is barrelled or bottled. The 
alcohol comes from the fermentation of the sugar contained in 
the juice. Sometimes sugar is added, there not being enough 
in the fruit juice. The fermentation is said to be spontaneous, 
because no yeast or other substance is added. But the germs 
of yeast are everywhere present in the air, and falling into the 
must, as the liquid before fermentation is called, it grows and 
multiplies and converts the sugar to alcohol. If air be excluded 
from sugar solutions and no yeast is added, fermentation will 
never take place. If the juice of fruits be first heated to destroy 
all yeast germs which may be in it, and then excluded from air 
to prevent their entrance, it will keep for an indefinite time 
without change. This explains why canning preserves fruits. 
If the exclusion of air be not perfect the canned article spoils, 
that is, ferments. 
Wine is made from a great variety of substances. Fermented 
or “ hard ” cider is wine of apples. The so-called wines in the 
market contain from three to twenty-five per cent of alcohol. 
They are frequently vile adulterations, or imitation mixtures, 
being made from raisins, with the addition of alcohol, flavoring 
extracts of coal-tar, sugar, and coloring matter, and sold under 
fictitious names. More wine is sold in civilized countries than 
could be made from all the grapes in the world. 
Palm wine, or toddy, is made from the sap of palm trees and 
is largely used in tropical countries. Pate wine, or secliar, was 
known to the Hebrews and is referred to as “ strong drink ” in 
the Old Testament. (See Lev. x. 9 and Deut. xiv. 26.) 
Gruarapo, or sugar-cane wine, is largely used also in tropical 
countries. In Mexico the national drink is pulque, a wine 
made from the juice of the maguey, a species of agave (century 
plant). 238 
LESSONS IN PHYSIOLOGY. 
5. The Danger in Wine.—If it were possible for all persons 
to control their appetites, and if wines were simply fermented 
juice of the grape with not more than five per cent of alcohol, 
an occasional moderate use of them could do but little harm. 
But much of the wine that is in use is strong in alcohol and 
contains other injurious ingredients, and the number who can 
use moderation in this respect is exceedingly small. The wise 
man who said, “ Wine is a mocker, strong drink is raging, and 
whosoever is deceived thereby is not wise,” understood the 
danger of tampering with such dangerous substances. A little 
creates a desire for more, and this still more, and the senses 
become blunted, the man’s judgment concerning the degree of 
its effect is impaired, and thus he is deceived by the mocker and 
is not wise. It must be borne in mind always that there is a 
great difference between the people of Italy and Greece in their 
non-stimulating climate, drinking, as a part of their daily food, 
wines made from the pure blood of the grape and containing 
but three or four per cent of alcohol, and the active, nervous 
American in our irritable atmosphere, drinking vile mixtures 
containing from twenty to twenty-five per cent alcohol. 
There may be poetry in the allusions made by literary men 
in all ages to wine and its influence upon humanity, but the 
ancient sage stated a pure scientific fact when he said, “ Wine 
is a mocker.” Modern physiologists and chemists confirm the 
statement, and all experience bears it out. 
6. Distilled Liquors. — These are the “ strong drinks ” of 
modern times. The ancients knew nothing of the process of 
distilling and the weaker wines, those made from fruits with a 
moderate amount of sugar, were called wines, and those from 
fruits containing much sugar, and therefore richer in alcohol, 
they called “ strong drink.” 
Alcohol is more volatile than water, that is, it is converted 
into vapor at a lower temperature. Herein lies the principle of 
distillation. A liquid containing alcohol is subjected to heat in 
a close vessel. A pipe connected with the vessel is carried by 
many coils or turns through cold water. The vapor passing 
through the pipe is condensed by the cold into liquid. This ALCOHOLIC BEVERAGES. 
239 
vapor contains more alcohol in proportion than water, and the 
condensed liquid discharged is stronger in alcohol than the 
original liquid. By repeated distillations almost pure alcohol 
is obtained. To get rid of the last portions of water is a diffi- 
cult process. It must be redistilled with certain salts which 
absorb the water. Alcohol thus freed from water is called abso- 
lute alcohol. The alcohol usually used in the arts and for mak- 
ing medicine is ninety-five per cent alcohol and five per cent 
water. 
The common distilled liquors are brandy, whiskey, rum, and 
gin. 
7. Brandy. — This is the product of the distillation of wine 
and contains from fifty to sixty per cent of alcohol. It has a 
peculiar flavor derived from certain oils that distil over with the 
alcohol. It is a strong and fiery drink, and very little of it pro- 
duces intoxication. 
8. Whiskey. — One of the most common forms of strong 
drink. It is usually made from Indian corn. Malted barley is 
added to the ground grain and a suitable amount of water. The 
malt changes the starch of the grain to sugar, which then takes 
on the vinous fermentation, after which the liquid is distilled. 
Whiskey is frequently made from wheat, rye, potatoes, and other 
vegetable substances containing starch. Its peculiar flavor is 
due to fusel oil, which is formed in the process and distils over 
with the alcohol. Whiskey contains from forty-five to sixty 
per cent or more of alcohol. The fusel oil gives it the peculiar 
burning effect when taken in the mouth. 
9. Gin and Rum. — Gin is produced in the same manner as 
whiskey, except that juniper berries are distilled with the grain. 
This gives its characteristic flavor. Rum is distilled from fer- 
mented molasses. 
10. Influence of Distilled Liquors. — All that has been said con- 
cerning the dangers of alcohol, applies to these strong liquors. 
They are the form in which alcohol is generally used when 
intoxication is desired. Alcohol alone cannot be used as a 
drink. It is too strong and the flavor is not pleasant to the 
majority of persons. Even when diluted with water it is seldom 240 
LESSONS IN PHYSIOLOGY. 
used, because not palatable, but when combined with the flavors 
of whiskey, brandy, gin, and rum or other distilled liquors, or in 
the form of wines and beers, it produces its evil effects. The 
confirmed drunkard, when he can get no other liquor, will drink 
alcohol, or, in fact, any mixture which which will intoxicate, for 
it is the intoxication that he desirds. In fact, the inebriate has 
very little sense of taste, his nerves having been blunted by the 
use of alcohol. Men drink for two reasons, because they love 
the taste and because they love the effect of the drinks. Were 
there no liquids but alcohol and water there would be fewer 
drunkards, because there would then be but one inducement 
instead of two. 
11. Adulteration of Liquors. — All kinds of beverages are 
largely adulterated in this country. Were the adulterations in 
use always harmless substances, as sugar, caramel, and water, 
the final effect would be for the better; but this is not the case. 
Some very poisonous substances are used in adulterating alco- 
holic drinks. Among the most common is cocculus indicus, a 
very poisonous vegetable substance which produces a kind of 
intoxication which is more injurious than that produced by 
alcohol. 
LESSON 47. 
Narcotic Drugs. 
1. Stimulants and Narcotics. — Stimulants are those agents 
which increase or intensify the forces of the system. Narcotics 
are those agents which paralyze or depress the forces of the sys- 
tem. These opposite effects are produced by the same agents, 
modified by the quantity, the age, the sex, the temperament, 
and the condition of health, the general law being that small 
quantities stimulate and large quantities depress, other things 
being equal, and that large quantities at first stimulate then 
depress. Large and small are relative terms, and what would 
be a large quantity for one person may he a small quantity for NARCOTIC DRUGS. 
241 
another. An stimulants, then, are narcotics when pushed to an 
extreme in quantity or continued in time. All narcotics are 
stimulants in small quantities and when first taken. This may 
be illustrated by a simple mechanical action. Gentle rubbing 
or tapping of the skin causes an increased flow of blood to the 
part and an agreeable sensation. This is stimulation. Let 
the pressure be very strong and the nerves are paralyzed and 
the blood driven away from the part. Or let the gentle action 
be kept up continuously for a long time, and there is a shock 
or paralysis of the nerves. This is narcotism. Some drugs are 
so powerful that but minute quantities produce the stimulating 
effect. Others are mild, and it requires a large quantity to pro- 
duce the narcotic effect. 
2. Opium.—One of the most seductive and dangerous of 
drugs, yet when properly used one of the most valuable. It is 
in the form of a gum, being the dried and thickened juice or 
milk of a species of poppy. The pods of the plant are cut in 
several places with a knife, which allows the milk to flow. 
In twenty-four hours it has dried and thickened on the pod and 
is scraped off and formed into balls. It is grown chiefly in Per- 
sia, Turkey, and India. It is bitter and disagreeable to the taste, 
and it is only for its effects that people use it. It is usually 
either eaten or smoked in a pipe. It is soluble in alcohol, the 
solution being known as laudanum. Sometimes it is taken in 
this form. 
The first effect of a dose of opium is an exhilaration of mind 
and a pleasurable or comfortable condition of the entire system, 
thus somewhat resembling the first effects of alcohol. Then a 
period of stupor and depression follows. A desire to sleep comes 
on, a sleep in which sometimes most extravagant dreams occur. 
On recovering from the stupor the body is weak, the head aches, 
and a miserable feeling makes the victim pay dearly for the 
pleasurable sensations experienced at first. When the habit of 
taking it is formed the person is the most abject slave imaginable. 
It is almost impossible for him to break off the habit. When 
deprived of the stimulant he is in a terrible torment and has no 
rest until he indulges again. Every time it requires a little 242 
LESSONS IN PHYSIOLOGY. 
more to produce the intoxication effect. After awhile he 
becomes subject to pains which opium will not relieve, digestion 
is impaired, the skin becomes yellow, the eyes sunken and glassy, 
there is a bending of the spinal column and emaciation of the 
body, and the victim is a hopeless wreck of humanity, both men- 
tally and physically. More so than alcohol it seems to destroy 
the moral sense. The confirmed opium-user, if he desires to be 
cured of the habit, must put himself under the closest kind of 
restraint, for while he may have been a conscientious man in 
other respects he will not hesitate to lie and steal to get the 
drug. 
There have been two remarkable cases of opium eating among 
men of genius, Thomas De Quincey and Samuel T. Coleridge. 
The former was an eminent English writer who had acquired 
the habit and after a long struggle succeeded in freeing himself. 
His “ Confessions of an Opium-Eater ” is interesting reading. 
Coleridge was one of England’s greatest poets, who in like man- 
ner became a victim and succeeded in breaking off the habit. 
These men are remarkable exceptions to the rule that whoever 
forms the habit is hopelessly lost. 
The people of Turkey, India, China, and other eastern coun- 
tries are much addicted to this habit. It is a worse evil 
among them than the alcohol habit is in our country. The 
habit is on the increase in the United States. It is believed 
by good authorities that the checking of the alcohol habit has 
led to an increase in the use of opium. If this be true it shows 
that we must strike deeper than prohibiting the manufacture 
and sale of alcoholic drinks. We must educate the people to see 
the evils of stimulants and narcotics of all kinds. 
Johnston’s “ Chemistry of Common Life ” thus sums up the 
effects of opium: — 
1. It is certain that opium, like spirituous liquors, produces most melancholy 
body-and-soul-destroying effects upon those who give themselves up to its use 
as a narcotic indulgence. If day brings them the bliss of heaven, night brings 
with it the torments of hell. 
2. It is certain, also, that some can continue for years to use it in small doses 
as a narcotic indulgence, without becoming slaves to it, or without appearing 
to be sensibly affected by it in their general health. NARCOTIC DRUGS. 
243 
3. But it Is of all indulgences the most wonderfully seductive, and is therefore 
a most dangerous substance to become familiar with. The infatuation some- 
times reaches such a point that the certainty of death, and all of the fearful in- 
firmities which in this case precede death, have no influence on the victim. 
4. To give up the indulgence produces tortures of mind and body, which 
makes cowards and recreants of the most resolute. To this fact, the testimony 
of Coleridge and De Quincey has been already quoted. 
3. Morphine. — This is simply an extract of opium, a con- 
centrated principle of the gum, having all its active narcotic 
properties in a much smaller bulk. It is a more convenient 
form for use in medicine, and many in our civilized countries 
are using it instead of opium for the intoxicating effect. It 
acts much more quickly and powerfully when dissolved and 
injected beneath the skin by an instrument called the hypo- 
dermic syringe. Not a few are using it in this manner as a 
constant habit. 
4. Indian Hemp. — Our common hemp plant, which is culti- 
vated in parts of this country for its fiber, contains a resinous 
substance which is strongly narcotic. In India this plant 
develops this resin in much greater quantities, and it is there 
gathered and used as a substitute for opium. The Arabians 
prepare from it a substance they call hasheesh. Immense 
quantities of this hemp resin are consumed, in Turkey, Arabia, 
and India. It is estimated that 300,000,000 people use it 
habitually. Its intoxicating effects differ considerably from 
opium, both in kind and degree. It induces a peculiar kind of 
temporary insanity, but does not affect the circulation and 
digestion as opium does. 
5. Coca. — This must not be confounded with the cocoa from 
which chocolate is made. It is an entirely different plant and 
possesses narcotic properties in the highest degree. It is the 
leaves of a bush six or eight feet high which grows in South 
America. The leaves are chewed or a tea is made from them 
and drank. Most extraordinary virtues are assigned to it by 
the natives who use it. They claim that by chewing the leaves 
they are enabled to endure the greatest fatigue and perform 
an immense amount of physical exertion without the need of 
food. The observations of many travellers confirm these re- 244 
LESSONS IN PHYSIOLOGY. 
ports, but a scientific man will regard them as exaggerations. 
There is scarcely an article in use as a medicine but at some- 
time in its history has been lauded to the skies for its extraor- 
dinary virtues. Opium when first introduced to the medical 
profession was called “Magnum Dei donum ” the great gift of 
God. Cinchona bark, from which quinine is made, was also 
attributed with extraordinary powers. Cocaine, an extract of 
coca, is now much employed in medicine. 
Coca is probably less dangerous as a narcotic indulgence 
than opium, hemp, and alcohol. It is in use by about 10,000,000 
people in South America. 
6. Betel-nut. — This is the seed of a species of palm tree, 
groAving in India and on the islands of the Indian Ocean. It 
is chewed like tobacco, and it is estimated that not less than 
50,000,000 people so use it. It gives a red color to the saliva 
and to the lips and teeth. This is considered very ornamental 
by the natives who use it. It seems to have narcotic effects 
somewhat similar to coca. 
7. Chloroform and Ether. — Perhaps no discovery of modern 
times has contributed more to human happiness than the discov- 
ery of the use of these substances as ancesthetics. An anaesthetic 
is a substance which produces unconsciousness to such a degree 
that any operation may be performed on the body without pain 
and without the knowledge of the patient. Previous to the use 
of anaesthetics in surgery, when it was necessary to amputate a 
limb or remove a tumor or growth, the patient was obliged to 
suffer extreme torment; and it required a number of assistants 
to hold him still long enough to perform the operation, which 
under such circumstances had to be done hurriedly, and neces- 
sarily in an imperfect manner. Now the patient lies down and 
inhales for a few minutes the vapor of chloroform or ether, and 
passes into a sleep as sound, and apparently as natural, as that 
of a child when undisturbed, and awakes in a few hours, know- 
ing nothing whatever of what has been done. It is true that in 
some rare cases death results from the use of these substances, 
yet the chances for recovery from the operation are so much 
greater, that there are few that are not willing to take the risk. NAttCOTIC DIIUGS. 
245 
Surgery has made wonderful advances since the introduction of 
anaesthetics, and hospitals which once were filled with shrieks 
and groans of the suffering patients are now transformed into a 
paradise in comparison. 
But there is no good thing that is not abused. There is grow- 
ing tendency among civilized people to use these substances for 
every ache and pain, and while it is not likely they will come 
into such habitual use as alcohol and opium, yet the danger is 
such as to call for warning. It is a safe rule never to use 
chloroform or ether without the advice of a competent physi- 
cian. 
8. Tobacco. — This is too well known to need description. 
The extent of its use is simply enormous. It is in use in all 
countries and by all races of men. Thirty years ago it was 
estimated that not less than 4,480,000,000 pounds were consumed 
annually, and since then it has been increasing. Its effects have 
been stated in the foregoing pages. We shall say here only 
that it is an injurious habit to all young persons, and to many 
adults, that to those past the middle age a moderate indulgence 
is generally beneficial, and that in many cases its use satisfies 
the longing for some kind of a stimulant, and doubtless saves 
many persons from the alcohol and opium habits. It is an 
expensive and filthy luxury, and if for no other reason it should 
be abstained from by the young. 
9. Other Narcotics. — There are numerous substances in use, 
taking the world over, which produce intoxicating effects in a 
greater or less degree. Thus various species of pepper which 
are known to possess narcotic properties are used in tropical 
countries. In Siberia a species of mushroom is largely used as 
a narcotic. Species of our common jimson weed are used in 
South America for the same purpose. The milky juice of let- 
tuce has been collected and dried and used as a substitute for 
opium in Europe. In Jamaica a plant called bull-hoof is used 
for its narcotic effect. 246 
LESSONS IN PHYSIOLOGY. 
TEST QUESTIONS FOR GENERAL REVIEW. 
Note. — The teacher who desires to hold an examination in Physiology may 
select ten or more of these questions as tests of the pupil’s knowledge. He may 
assign the whole list for study, and then select a given number and require the 
pupils, without access to books, to write out answers to them, the pupils not to 
know what the test questions are until required to answer them. It must be 
remembered that examinations are only partial tests of knowledge. As a gen- 
eral rule, examinations should be more of the nature of a general review of the 
subject. 
1. Who discovered the circulation of the blood ? When ? Read a sketch of 
his life in any encyclopaedia or biographical dictionary. What can be said of 
the importance of this discovery ? 
2. Why is disease now less dreaded than in the Middle Ages ? 
3. What is a cell ? What is life ? 
4. What do you mean by the word tissue? Can we speak of the blood as 
“tissue” ? 
5. What organs constitute the Digestive System ? What is the use, stated 
in a few words, of the Digestive System ? 
6. What three elements compose in great part the human body ? 
7. Write an essay on Bones, using the following outline of points to be dis- 
cussed : 1. Number; 2. Sizes and shapes ; 3. Structure and composition; 4. How 
joined together ; 5. Properties and uses ; 6. Growth and repair ; 7. How to care 
for them. 
8. Suppose a man’s arm to be amputated half-way between elbow and shoul- 
der, what structures can you name that would be severed ? In like manner 
name the parts severed in cutting off the head; in cutting the body through at 
the lower point of the sternum. [Similar questions should be proposed. It is 
an excellent method of testing the pupil’s knowledge of the relation of bones, 
muscles, arteries, and nerves.] 
9. Write an essay on Digestion, discussing briefly the organs, processes, 
results, uses, and hygiene of digestion. 
10. Name the heat-making element in each of the following articles: Wheat, 
bread, rice, potatoes, dates, cocoanuts, bacon. 
11. Name the tissue-making element in beans, bacon, milk, and wheat bread. 
12. What is the hardest and most durable substance in an animal body ? 
13. Describe a proper method of ventilating a room. 
14. What are the advantages of full and deep breathing ? 
15. What would be the probable effect of a removal of the entire epidermis ? 
16. What is protoplasm ? 
17. What is the function of the red corpuscles ? 
18. What are cilia, and what is their use ? 
19. What is the office of the Eustachian tube ? Of the tympanum ? 
20. Where is the organ of Corti ? What is its supposed function ? 
21. What is the remedy for near-sightedness ? INDEX AND GLOSSARY. 
A HINT TO THE STUDENT. 
The most valuable part of any book is the index. Study the subject and not the 
book. Use the book in studying the subject. You cannot use a book with economy 
of time without using the index. The more practice you have in looking up words in 
the index the quicker you will find them. Do not pass over words in the text which 
you do not understand. If the word is not defined in its connection, or not made 
clear by the context, look for it at once in the index. It will either be defined there 
or the figures will refer you to the part of the text where it is made clear. A teacher 
can help you much, but you need not depend on a teacher. This book is a self- 
instructor, if used as here directed. Where several page numbers are given, look for 
each of them. 
A. 
Abdomen (L. abdere, to hide), the largest 
cavity in the body, containing the 
stomach, liver, intestines, etc. 
Abdominal brain, 158. 
Abdueens nerve (L., to lead away), 156. 
Aberration, 187. 
Absolute alcohol, 239. 
Absorbents, the vessels concerned in ab- 
sorption. They are the capillaries, 
the lacteals, and the lymphatics. 
Absorption (L. ab and sorbere, to suck 
in), 
in the mouth, 57. 
experiment to illustrate, 59. 
from the stomach, 62. 
from intestine, 73. 
by capillaries, 97. 
from surfaces, 141. 
internal, 142. 
Accommodation, function of, 185. 
Acetabulum, the round cavity in the 
innominata bone which receives the 
head of the femur; so called from L. 
acetum, vinegar, because of its re- 
semblance to a vinegar vessel. 
Achilles, tendon of, 38. 
Achromatic lenses, 187. 
Acid, a substance usually sour to the 
taste and having certain definite 
chemical properties. Acids are of 
an opposite nature to alkalies. 
Actions of muscles, 40. 
“Adam’s apple.” The larynx is more 
prominent in men than in women. 
This name was applied to the promi- 
nence in the throat from the fanciful 
notion that the apple given Adam by 
Eve stuck in his throat. 13,114. 
Adipose tissue (L. adeps, fat), 61. 
Adjustment of the eye, see Accommoda- 
tion. 
Adulteration of liquors, 240. 
After-images, 188. 
“ Ague cake,” 71. 
Air, 
composition of, 121. 
effects of respiration on, 121. 
pure, 124. 
moisture in, 125. 
dust in, 125. 
draughts of, 126. 
of sick-rooms, 128. 
Air-cells of lungs, 117. 
Albinos (L. albus, white), 133. 
Albumen, or albumin (L. albus, white), 75. 
Albuminose, 60. 
Albuminous substances. This term is 
generally used synonymous with 
“nitrogenous substances.” It is a 
peculiar fact that nitrogen is a con- 248 
INDEX. 
stituent element of all living beings 
as well as one of the elements of 
most all unstable and explosive 
chemical compounds, while in itself 
it is an inert substance characterized 
by its negative properties only. Al- 
bumen is taken as the type of the 
nitrogenous substances which are 
capable of being transformed into 
the tissues of the body. 60, 75. 
Alcohol, 
effect on muscles, 49. 
osseous system, 31. 
digestive system, 83. 
circulatory system, 112. 
respiratory system, 129. 
secretory system, 147. 
nervous system, 173. 
special senses, 207, 231. 
summarized, 231. 
general description of, 230. 
Alcoholic beverages, 234. 
Aleurone, 211. 
Alexis St. Martin, 62. 
Aliment (L. alo, to nourish), food, nutri- 
ment. 
Alimentary canal, 51. 
Alkali, a substance having chemical 
properties opposite to those of acids. 
Potash, soda, and lime are the most 
familiar examples. 61. 
Allspice, 222. 
Amoeboid movements of white corpuscles 
(from amczba, Gr. amoiba, a change), 
101. 
Anaesthetics (Gr. ana, without; aisthenai, 
feeling), 244. 
Anastomosing (Gr. anastomoun, to fur- 
nish with a mouth), 94. 
Anatomy defined, 2. 
Anger and digestion, 64. 
Animal charcoal, 25. 
Animal food, 79. 
Animal heat, 75. 
Anterior nares, 202. 
Antihelix, 193. 
Antiseptic treatment (L., opposing putre- 
faction), 126. 
Aorta, 92. 
Apparatus, 4. 
Appendages of skin, 134. 
Appendix, vermiform, 67. 
Appetite, a guide, 78. 
Apples, 218. 
Apricots, 218. 
Aqueous humor (L. aqua, water), 181. 
Arachnoid membrane, 150. 
Arbor vitae, 153. 
Areolae (L., diminutive of area), 132. 
Arrow root, 213. 
Arteries (Gr. aer, air, and tereo, to con- 
tain), supposed by the ancients to 
contain air, 92, 94. 
Articulations (L. articulo, I join), 16. 
Arytenoid cartilage (Gr. arytainai, a 
ladle), 115. 
Assimilation, 74. 
Astigmatism (Gr. a, without, and stigma, 
a point), 191. 
Astragalus, 15. 
Atlas, 12. 
Atropa belladonna, a medicine.used to 
dilate the pupil of the eye, 186. 
Audiphone, 200. 
Auditory canal, 193. 
Auditory judgments, 200. 
Auditory nerve, 156. 
Auditory sensations, 199. 
Auricles (L. auricula, a little ear), 88. 
Automatic action, 166. 
Avocation, 48. 
Axillary artery, 93. 
Axis, 12. 
Axis cylinder, 159. 
B. 
Bacteria, 126. 
Barley, 212. 
Base-ball, 47. 
Basilar artery, 93. 
Bathing, 
kinds of baths, 144. 
value of, 143. 
Beans, 213. 
Beaumont, Dr., 62. 
Beef, 215. 
Beer, 235, 236. 
Betel nut, 244. 
Biceps, 36. 
“ Big neck,” 109. 
Bile, 69, 73. 
Bipenniform (L. bi, two, and penna, a 
feather), 36. 
Blackberries, 219. 
Bleeding, to stop, 110. 
Blindness, color, 191. 
Blind spot, 189. 
Blister, 132. 
Blood, 
amount of, 99. 
composition of, 99. 
circulation of, 102. 
properties of, 99, INDEX. 
249 
Blood-sliot eyes, 179 
Boat rowing, 46. 
Bolus, 62. 
Bones, 7, 
articulations of, 16. 
composition of, 22. 
covering of, 20. 
development of, 26. 
growth of, 28. 
hygiene of, 29. 
number of, 7. 
ossification, 26. 
properties of, 24. 
repair of, 28. 
relation to muscles, 42. 
structure of, 21, 22. 
uses of, 24. 
Brachial artery, 94. 
Brachial plexus, 155. 
Brain, 
coverings of, 150. 
divisions of, 150. 
location of, 149. 
size of, 149. 
structure of, 152. 
Brandy, 239. 
Breathing exercise, 129. 
Bronchi, 115. 
Buckwheat, 213. 
Bunions, 147. 
Buttermilk, 226. 
C. 
Cabbage, 219. 
Calorifacient foods, 75. 
Camera obscura, 183. 
Canaliculi, 22. 
Canals, semicircular, 196. 
Canine teeth, 52. 
Capacity of lungs, 117. 
Capillaries, 97. 
Capsular ligaments, 16. 
Carbo-hydrates, 75. 
Carbon (L. carbo, coal), 4. 
Carbonaceous foods, 75. 
Carbon dioxide, 121,124. 
Cardiac orifice, 60. 
Carotid artery, 93. 
Carpenter, Dr., on diet, 79. 
Carpus, 14. 
Carriage riding, 46. 
Carrots, 219. 
Cartilage, 17. 
Cataract, 191. 
Catarrh, 27. 
Cavities of heart, 87. 
Celery, 219. 
Cell, defined, 2. 
Cellular coat, 60, 67. 
Cement, 54. 
Centres of ossification, 26. 
Cerebellum, 151. 
Cerebrum, 150. 
Ceruminous glands (L. cera, wax), 193. 
Cervical nerves, 155. 
Cervical vertebrae, 12. 
Chafing and chapping of the skin, 146. 
Cheese, 217. 
Chemistry of body, 4. 
Cherries, 218. 
Chicory, 228. 
Chloroform, 244. 
Chocolate, 82, 83. 
Cholera, 225. 
Choroid membrane, 179. 
Chromatism, 186. 
Chyle, 72, 108. 
Chyme, 61. 
Chymification, time required, 62. 
Cider, 226. 
Cigarette smoking, 207. 
Cilia, 116, 182. 
Ciliary muscle, 179. 
Ciliary processes, 179. 
Ciliated epithelium, 116, 137. 
Circulation, 97, 
rate of, 105. 
special, 103. 
causes of, 103. 
exercise and, 111. 
cold and heat and, 111. 
nervous shocks and, 111. 
alcohol and, 112. 
tobacco and, 112. 
Circulatory system, 87. 
Circumvallate papillae, 203. 
Clams, 217. 
Clavicle, 11. 
Cleanliness, 143. 
Clothing, 76, 145. 
Cloves, 82. 
Club-foot, 38. 
Coagulation, 101. 
Coca, 243. 
Cocoaine, 244. 
Coccygeal nerves, 155. 
Coccyx, 13. 
Cochlea, 196, 199. 
Cocoa bean, 228. 
Cocoanuts, 214. 
Cceliac axis, 94. 
Coffee, 82, 83, 228. 
“ Colds,” 126. 250 
INDEX. 
Cold drinks, 81. 
Coleridge, 242. 
Colon, 67. 
Color blindness, 191. 
Color of eyes, 180. 
lungs, 117. 
Complemental air, 120. 
Complementary colors, two colors which 
by their mixture produce white light 
are called complementary, 188. 
Concha, 193. 
Condiments, 81, 82, 221. 
Conjunctiva, 177. 
Convolutions of brain, 151. 
Cooking, 79. 
Cords, vocal, 115. 
Corium, 132. 
Corn, 212. 
Cornea, 179. 
Corns, 147. 
Corpus callosum (L., hard body), 151. 
Corpuscles (L., diminutive of corpus, 
body), 99, 100. 
Corpus striatum (L., striped body), 153. 
Corsets, 30. 
Cortical substance (L. cortex, bark), 54. 
Corti, organ of, 196. 
Course of the blood, 102. 
Covering of bones, 20. 
Cranberries, 220. 
Cranial nerves, 155. 
Cranium, 7. 
“Crazy-bone,” 14. 
Cricoid cartilage, 115. 
“ Cross-eyes,” 178. 
Crusta petrosa (L., stony crust), 54. 
Crying, 123. 
Crystalline lens, 181. 
Cucumbers, 219. 
Cuneiform bone, 14. 
Currants, 220. 
Cystic duct, 69. 
D. 
Daltonism, 191. 
Dandruff, 131. 
Dates, 214. 
Decay of body, 5. 
Deglutition (L. de, down, and glutire, to 
swallow), 58. 
Deltoid muscle, 37. 
Dental pulp, 54. 
Dentine, 54. 
De Quincey, 242. 
Derbyshire neck, 109. 
Derma, 132. 
Desks for pupils, 29. 
Development of bone, 26. 
teeth, 54. 
Diapedesis (Gr. dia, through, and pedan, 
to leap), 101. 
Diaphragm, 119. 
Diaphysis, 27. 
Diet, variety in, 80. 
Digestive system, 51. 
Digestion (L. digerere, to separate), 
in the mouth, 56. 
stomach, 61. 
intestine, 72. 
Diploe (Gr. diploe, two-fold), 21. 
Distilled liquors, 238. 
Dorsal nerves, 155. 
Dorsal vertebrae, 13. 
Double vision, 187. 
Draughts, danger in, 126. 
Drinks, non-alcoholic, 222. 
Duodenum (L., for twelve, because as long 
as the breadth of twelve fingers), 65. 
Dura mater, 150. 
Dust and disease, 125. 
E. 
Ear, 
external, 193, 197. 
middle, 194, 197. 
internal, 195, 198. 
hygiene of, 207. 
bones of, 195, 198. 
wax, 193, 201, 208. 
stones, 196. 
Eating, 
regularity in, 80. 
frequency of, 81. 
manner of, 81. 
Eggs, 215, 216. 
Emotions, 64. 
Emulsion (from a Latin word meaning 
“to milk ”), 72. 
Enamel, 54. 
Endocardium, 90. 
Endolymph, 196. 
Endosteum, 20. 
Endothelium, 138. 
Ensiform appendage (L. ensis, a sword), 
10. 
Epidermis (Gr. epi, upon, and, derma, 
skin), 131. 
Epiglottis (Gr. epi, upon, and glottis, the 
entrance to the windpipe), 115. 
Epihyal hone, 28. 
Epiphysis, 26. 
Epithelium, 137. INDEX. 
251 
Erect image, 185. 
Erect posture, 30. 
Esophagus (Gr. oisophagos, food car- 
rier), 57. 
Ether, 244. 
Ethmoid bone, 9. 
Eustachian tube, 57, 194, 198. 
Eustachian valve, 88. 
Excretion defined, 139. 
Exercise, 
alternation with rest, 45. 
effects of, 47. 
and digestion, 64. 
and respiration, 128. 
kinds of, 46. 
time for, 48. 
necessity of, 44. 
violent, 47. 
Expiration, 120. 
Extensor muscles, 36. 
External iliac artery, 94. 
External rectus muscle, 177. 
Eye, 
structure of, 177. 
physiology of, 183. 
hygiene of, 206. 
Eyeball, 177. 
Eyebrows, 181. 
Eyelashes, 182. 
Eyelids, 182. 
Eye teeth, 52. 
F. 
False ribs, 10. 
False vocal cords, 115. 
Fang of tooth, 53. 
Far-sightedness, 190. 
“ Father of medicine,” 1. 
Fatigue, 205. 
Fats, 214. 
Fauces, 52. 
Feeling, sense of, 204. 
Femoral artery, 94. 
Femur, 15. 
Fenestra ovalis, 194. 
Fenestra rotunda, 194. 
Fermented liquors, 234. 
Fiber of muscle, 39. 
nerve, 158. 
Fibril, 40. 
Fibrin, 102. 
Fibrous tissue, 3. 
Fibula, 15. 
Filiform papillae, 203. 
Fisli, 217. 
Fissures of liver, 68. 
Flat bones, 19. 
Flesh, 35. 
Flexor muscles, 36. 
Floating ribs, 10. 
“ Flying flies,” 190. 
Focus in camera, 183. 
Fontanelles, 27. 
Foods, 
classified, 75. 
quantity, 77. 
quality, 78. 
cooking, 79. 
and drinks, how to choose, 211. 
Foreign object in eye or ear, 206, 208. 
Fossa of helix (L., a ditch), 193. 
Fractures of bones, 28, 30. 
Freckles, 133. 
Frequency of eating, 81. 
heart beat, 90. 
Frontal bone, 8. 
Frontal sinus, 27, 29. 
Frying, 80. 
Fulcrum, bones as, 42. 
Functions of different organs, see under 
names of organs. 
Fungiform papillae, 203. 
Fusiform muscles, 36. 
G. 
Gall bladder, 69. 
Gall cyst, 69. 
Game, 216. 
Ganglia, 155. 
Gases, exchange of, 121. 
Gastric artery, 94. 
Gastric juice (Gr. gaster, stomach), 60. 
Gelatine, 23, 75, 220. 
General sensation, 205. 
Germs of disease, 126. 
Gin, 239. 
Ginger, 222. 
“ Ginger ale,” 227. 
Gladiolus, 10. 
Glands, 
ceruminous, 193. 
salivary, 55. 
parotid, 55. 
sublingual, 56. 
submaxillary, 56. 
sebaceous, 136. 
sudoriparous, 136. 
pancreas, 71. 
spleen, 71. 
liver, 68. 
lymphatic, 107. 
thymus and thyroid, 109. 
Meibomian, 182. 252 
INDEX. 
Glottis, 115. 
Glucose, 70, 214. 
Gluten, 61, 75, 211. 
Glycogen, 70. 
Goitre, 109. 
“ Goose-flesh,” 35. 
Graham bread, 212. 
Grapes, 219. 
“Greens,” 220. 
Grief and digestion, 64. 
Gristle, see Cartilage. 
Groaning, 128. 
Grunting, 128. 
Gullet, 57. 
Gustatory bulbs, 203. 
Gymnastic exercises, 47. 
H. 
Habit, force of, 168. 
Hair, 134. 
Ham-strings, 38. 
Handkerchief bandage, 110. 
Harvey, William (b. 1578, d. 1657), an emi- 
nent English physician and surgeon, 
discoverer of the circulation of the 
blood, 1. 
Haversian canals, 22. 
Hawking, 123. 
Heart, 
cavities of, 87. 
auricles, 88. 
ventricles, 88. 
valves, 88. 
structure, 90. 
sounds of, 90. 
work of, 91. 
size and shape, 87. 
Heat, animal, 75. 
Helix, 193. 
Hemaglobin, 99, 101. 
Hemispheres of brain, 151. 
Hemp, 243. 
Hepatic artery (Gr. hepars, liver), 69. 
Hepatic duct, 69. 
Hepatic veins, 69. 
Hiccough, or hickup, 122. 
Hippocrates, 1. 
Histogenetic food, 75. 
Histology, 3. 
Horseback riding, 46. 
Hot water, 82. 
Humors of eye, 181. 
Hunger, 205. 
Hydrocarbons, 75. 
Hydrogen (Gr. hudor, water, and genein, 
to generate), 4. 
Hygiene, 
defined, 2. 
of bones, 29. 
muscles, 44. 
digestion, 77. 
secretory system, 143. 
nervous system, 170. 
circulation, 110. 
respiration, 124. 
special senses, 206. 
Hyoid bone, 13. 
Hypermetropy, 190. 
Hypoglossal nerve, 156. 
I. 
Ileum (Gr. eilein, to twist), 66. 
Ilium (L. ilia, the flank), 13. 
Images, 184, 188. 
Immovable joints, 18. 
Improper ventilation, 127. 
Incus, 195. 
Inferior maxillary bone, 9. 
Inferior oblique muscle, 178. 
Inferior rectus muscle, 177. 
Inferior vena cava, 88, 89. 
Infundibulum, 196. 
Innominata artery, 93. 
Innominata bone, 13. 
Insalivation, 58. 
Insect in ear, 208. 
Insensible perspiration, 140. 
Inside of body, 137. 
Inspiration, 119. 
Intensity of sound, 199. 
Intercostal muscles, 37. 
Internal carotid artery, 93. 
Internal iliac artery, 94. 
Internal rectus muscle, 178. 
Intertubular tissue, 54. 
Intestinal juice, 67, 73. 
Intestines, 
small, 65. 
large, 66. 
structure of, 67. 
Iris (L., a rainbow), 180,186. 
Irradiation, 188. 
Irregular bones, 20. 
J. 
Jaw-bones, 9. 
Jejunum, 66. 
Joints, 16. 
Judgments, auditory, 200. INDEX. 
253 
Juice, 
gastric, 60. 
intestinal, 67. 
pancreatic, 70, 73. 
K. 
Kidneys, 141. 
L. 
Labyrinth, 195, 196. 
Lachrymal bones, 9. 
Lachrymal canals, 182. 
Lachrymal duct, 182. 
Lachrymal sac, 182. 
Lacteals (L. lac, lactis, milk), 67, 73,107. 
Lacunae, 22. 
Laminae, 11. 
Large intestine, 66. 
Larynx, 114. 
Laudanum, 241. 
Laughing, 123. 
Lawn tennis, 47. 
Leaders, 38. 
Leaping, 47. 
Legumin, 61, 75. 
Lemons, 219. 
Lens, crystalline, 181. 
Life, 3. 
Ligaments (L. ligo, I bind), 16. 
Light in reading, 206. 
Light, regulating in the eye, 186. 
Liquor sanguinis, 99. 
Liver, 
location, size, and shape, 68. 
structure, 68. 
vessels, 68. 
lobes, 68. 
Lobule of ear, 193. 
Long bones, 19. 
Loudness of sound, 199. 
Lumbar nerves, 155. 
Lumbar vertebrae, 13. 
Lung capacity, 121. 
Lungs, 117. 
Lymph, 108. 
Lymphatic system, 106. 
Lymphatic system, functions of, 109. 
Lymphatic vessels and glands, 107. 
M. 
Macaroni, 212. 
Malleus, 195. 
Mastication, 58. 
Mastoid bone, 8. 
Mastoid cells, 194. 
Matrix of nail, 134. 
Meatus auditorius externus, 193. 
Mechanism of inspiration, 119. 
expiration, 120. 
Medulla oblongata, 152, 163. 
Meibomian glands, 182. 
Melons, 219. 
Membranes, mucous and serous, 137. 
Membranous labyrinth, 196. 
Mental development, food for, 79. 
Middle ear, 194. 
Milk, 217. 
Milk teeth, 52. 
Mitral valve, 89. 
Modified respiratory movements, 121. 
Modiolus, 196. 
Moisture in the air, 125. 
Molars, 52. 
Morphine, 174, 243. 
Motions of heart, 90. 
Mucous membrane, 60, 116, 117,131. 
Muscae volitantes, 190. 
Muscles of the eyeball, 177. 
skin, 132. 
Muscular sense, 204. 
Muscular system, 35. 
Mushrooms, 220. 
Musical sounds, 199. 
Mustard, 222. 
Myopy, 190. 
N. 
Nails, 134, 146. 
Naming muscles, 36. 
Narcotics, 240, 245. 
Nasal bones, 9. 
Nasal catarrh, 27. 
Nasal fossae, 202. 
Nausea, sickness of the stomach, with in- 
clination to vomit. 
Near-sightedness, 190. 
Nerves, 
structure of, 158. 
composition of, 160. 
Nervous shocks, 111. 
Nervous system, 149,170. 
Neuroglia, 158. 
Neurilemma, 159. 
Nightmare, 169. 
Nitrogen, 121. 
Nitrogenous substances, 75. 
Noises, hearing, 199. 
Nostrils, 202. 
Nutrition, 142. 254 
INDEX. 
O. 
Oatmeal, 212. 
Occipital bone, 8. 
Occipito-froutalis muscle, 36. 
Occupation and food, 77. 
Odontoid process, the peg-like process 
of the axis on which the head rotates 
(Gr., “ tooth-like ”), 12. 
Oil-glands, 136. 
Oils, 214. 
Old-sightedness, 190. 
Olecranon process, 15. 
Olfactory nerve, 156, 202. 
Opium, 174, 241. 
Optic nerve, 156. 
Optic thalamus, 153. 
Oranges, 219. 
Orbits, 177. 
Organ defined, 3. 
Organ of Corti, 196. 
Originators of nerve-force, 161. 
Os hyoides, 13. 
Osmose, 104. 
Osseous system, 7. 
Ossicles, 195,198. 
Ossification, 26. 
Otoliths, 196. 
Oxygen, 3,114,121. 
Oysters, 217. 
P. 
Pain, 167. 
Palate-bone, 9. 
Palmar arch, 94. 
Pancreas, 70. 
Pancreatic juice, 70, 71, 73. 
Papillary layer, 132. 
Parietal bone, 8. 
Parsnips, 219. 
Patella, 15. 
Pathetic nerve, 156. 
Peaches, 218. 
Pears, 218. 
Peas, 213. 
Pectin, 220. 
Pectoralis major muscle, 37. 
Peculiarities of hair, 135. 
skin, 133. 
teeth, 55. 
Pelvis, 13. 
Penniform, 36. 
Pepper, 222. 
Pepsin, 60. 
Peptones, 60. 
Pericardium, 89. 
Perilymph, 196. 
Perimysium, 40. 
Perineurium, 159. 
Periodical action of stomach, 64. 
Periosteum, 20. 
Peristaltic action, 61. 
Peritoneum, 68, 138. 
Peritonitis, 139. 
Permanent cartilage, 17. 
Permanent teeth, 52. 
Perspiration, 140. 
Petrous bone, 8. 
Phalanges, 14. 
Pharynx, 57. 
Phosphenes, 189. 
Physical development, 79. 
Physiology defined, 2. 
Pia mater, 150. 
Picture on retina, 184. 
Pigment of hair, 135. 
skin, 131. 
Pinna, 193. 
Pisiform bone, 14. 
Plasma, 99, 108. 
Pleura, 118. 
Plexuses, 155,157. 
Plums, 218. 
Pneumogastric nerve (Gr. pneumon, the 
lungs, and gaster, the stomach), also 
called par vagum, or the wandering 
pair of nerves. Its distribution is 
wider than that of any of the cranial 
nerves. It is the principal nerve of 
respiration and exercises an inhibi- 
tory or checking power on the heart. 
156. 
Pneumonia, inflammation of the sub- 
stance of the lungs; a very frequently 
fatal disease, often called lung fever. 
Poisons, 146. 
Pons Varolii, 151, 163. 
Popliteal artery, 94. 
Pork, 216. 
Portal vein and portal circulation, 68,103. 
Posterior tibial artery, 94. 
Posture, erect, 30. 
Potatoes, 213. 
Poultry, 216. 
Prehension, 74. 
Presbyopy, 190. 
Processes of vertebrae, 12. 
Properties of bones, 24. 
Proper ventilation, 128. 
Protectors of eye, 181. 
Proteids, 60. 
Protoplasm, 2,101. 
Provisional callous, 28. 
Ptyalin, 56. INDEX. 
255 
Pulmonary circulation, 103. 
Pulse tracing, 104. 
Pumpkins, 219. 
Pupil of eye, 180. 
Pure air, 124. 
Pure water, 223. 
Pyloric orifice, 60. 
Pylorus, 60. 
Q. 
Quality of food, 78. 
sound, 200. 
Quantity of food, 77. 
Quinine, 175. 
Quinsy, 52. 
R. 
Radial artery, 94. 
Radiating muscles, 36. 
Radius, 14. 
Raspberries, 219. 
Rate of circulation, 105. 
respiration, 120. 
Reading, light and eyes, 207. 
Receiving organs, 161. 
Receptaculum cliyli, 107. 
Reflex action, 123,164,166. 
Regularity in eating, 80. 
Relation of muscles to bones, 42. 
Reserve air, 120. 
Residual air, 120. 
Respiration, 119, 121,128, 129. 
Respiratory center, 163. 
Rest, 42, 43, 64, 171, 207. 
Retina, 180, 184. 
Rhubarb, 219. 
Ribs, 10. 
Rice, 212. 
Riding, 46. 
Rima glottidis, 115. 
Rivinianus, ducts of, 56. 
Rods and cones, 180. 
Rods of Coi’ti, 196. 
Roots of spinal nerves, 157. 
Rowing, 46. 
Rum, 239. 
Running, 47. 
Rye, 212. 
S. 
Saccharose, 214. 
Saccule, 196. 
Sacral nerves, 155. 
Sacrum, 13. 
Sago, 213. 
Saliva, 56, 72. 
Salivary glands, 55. 
Salt, 221. 
Sarcolemma, 40. 
Sarcous elements, 40. 
Sarsaparilla, 227. 
Sartorius, 37. 
Scaphoid, 14,15. 
Scapula, 11. 
Schneiderian membrane, 202. 
Schwann, white substance of, 159. 
Sclerotic coat, 178. 
Sebaceous glands, 132. 
Secretion, 74,140. 
Secretory system, 131, 143,147. 
Semicircular canals, 196,199. 
Semilunar bone, 14. 
Semilunar valves, 89. 
Sensation, general, 205. 
Serous membranes, 138. 
Serum, 102, 108. 
Sesamoid bones, 28. 
Short bones, 19. 
Sick-rooms, air of, 128. 
Sighing, 122. 
Sinews, 38. 
Single and double vision, 187. 
Sinuses of bone, 27. 
dura mater, 97. 
Skating, 46. 
Skeleton (Gr. skeletos, dried up), 16. 
Skin, 
layers, 131. 
muscles of, 133. 
peculiarities of, 133. 
uses of, 133. 
glands of, 132. 
appendages of, 134. 
Sleep, 64,168, 172. 
Small intestines, 65. 
Smell, 202. 
Smoking, 207. 
Sneezing, 123. 
Sobbing, 122. 
“ Soda water,” 226. 
Solar plexus, 157. 
Somnambulism (L., “ sleep-walking ”), 
169. 
Sound, 197. 
Sounds of heart, 90. 
Sphenoid bone, 8. 
Sphincter muscles (from Gr. word, mean- 
ing “ to bind tight ”), 36. 
Sphygmograph, 104. 
Spices, 222. 
Spinal accessory nerve, 156. 
Spinal canal, 12. 256 
INDEX. 
Spinal column, 11. 
Spinal cord, 149, 153, 154, 165. 
Spinal nerves, 155, 157. 
Spinous processes, 12. 
Spleen, 71. 
Squamous bone, 8. 
Squashes, 219. 
Stapes, 195. 
Starch, 61. 
Steapsin, 71. 
Stenson’s duct, 55. 
Sterno-cleido-mastoid muscle, 36. 
Sternum, 10. 
Stimulants, 240. 
Stomach, 
location, 60. 
coats, 60. 
secretion of, 60. 
digestion in, 61, 63. 
digesting itself, 62. 
absorption from, 62. 
Strawberries, 219. 
Strength of muscles, 43. 
Striated muscles, 40. 
Structure of organs, see under names of 
respective organs. 
Subclavian artery, 93. 
Sublingual gland, 56. 
Submaxillary gland, 55. 
Substance of bone, 20. 
Succory, 228. 
Sudoriparous glands (L. sudor, sweat), 
136. 
Sugar, 214. 
Superficial veins, 95. 
Superior maxillary bone, 9. 
Superior mesenteric artery, 94. 
Superior oblique muscle, 178. 
Superior rectus muscle, 177. 
Superior vena cava, 96. 
Superior vocal cords, 115. 
Sutures, 18, 
Sweat ducts, 132,136. 
Sweat glands, 136. 
Sweat pores, 132, 136. 
Swimming, 46. 
Sympathetic system, 157,169. 
Synovia, 17. 
System defined, 4. 
Systemic circulation, 103. 
T. 
Tannic acid, 227. 
Tapioca, 213. 
Tarsus, 15. 
Taste, 203. 
"Taste buds,” 203. 
Tea, 
Chinese, 83,174, 227. 
Paraguay, 228. 
Abyssinian, 228. 
Tears, 182. 
Teeth, 
classes of, 52. 
structure of, 53. 
development of, 54. 
peculiarities of, 55. 
uses of, 55. 
care of, 85. 
Temperance reform, 233. 
Temperature, 64, 81, 204. 
Temporal bone, 8. 
Temporal muscle, 36. 
Temporary teeth, 52. 
Tendons, 37. 
Tennis, 47. 
Terminations of nerves, 159. 
Theine, 227. 
Thirst, sensation of, 205. 
Thoracic aorta, 93. 
Thoracic duct, 73,107. 
Thorax, 10. 
Thymus gland, 109. 
Thyroid cartilage, 114. 
Thyroid gland, 109. 
Tibia, 15. 
Tibialis muscle, 36. 
Timbre, 200. 
Tissue adipose, 61. 
Tissue defined, 3. 
Tobacco, 84, 112,129, 245. 
Toddy, 237. 
Tomatoes, 220. 
Tongue, 203. 
Tonicity, 45. 
Tonsils, 52. 
Tonsilitis, 52. 
Toothpicks, 85. 
Touch, 204, 205. 
Trachea (Gr. trachus, rough), 115. 
Tragus, 193. 
Transmitting nerve-force, 161. 
Trapezium, 14. 
Trapezoid, 14. 
“ Tree of life,” 153. 
Trephine, or trepan, 21. 
Triceps, 37. 
Trifacial nerve, 156. 
Trigeminal nerve, 156. 
True skin, 131. 
Trunk, bones of, 10. 
Trypsin, 71. 
Tubes, Eustachian, 57. INDEX. 
Tubuli dental, 54. 
Tunics of eye, 178. 
Turnips, 219. 
Tusks, 53. 
Tympanic membrane, 194,197. 
Tympanum (Gr. tumpanon, a drum), 194. 
Typhoid fever, 224. 
U. 
Ulna, 14. 
Ulnar artery, 94. 
Ulnar nerve, 14. 
Ultimate fibers, 39. 
Unciform hone, 14. 
Urea, 141. 
Ureters, 141. 
Utricle, 196. 
V. 
Vagus nerve, 156. 
Valves, 
of heart, 88. 
of veins, 97. 
pyloric, 60. 
illeo-coecal, a fold in the intestine be- 
tween ileum and ccecum. 
Vasa vasorum, 98. 
Vaso-motor center, 164. 
Veins, 95, 97. 
Vena cava, 96. 
Ventricles of brain, 153. 
heart, 89. 
Vermicelli, 212. 
Vermicular motion, 61. 
Vermiform appendix, 67. 
Vertebra, 11. 
Vertebral artery, 93. 
Vessels of liver, 68. 
Vestibule, 195. 
Villi (L. villus, the nap of cloth, a tuft), 
67, 73. 
Vinegar, 221. 
“ Vital knot,” 163. 
Vitreous humor (glassy), 181. 
Vocal cords, 115. 
Vocal sounds, 123. 
Vocation, 48. 
Voice, 114. 
Vomer, 9. 
Vomiting center, 164. 
W. 
Walking as exercise, 46. 
Warm drinks, 227. 
Water, 
in food, 223. 
composition of, 223. 
unwholesome, 224. 
tests for, 225. 
use of, in body, 222. 
taken with food, 82. 
Waste and repair, 142. 
Weak eyes, 207. 
Wheat, 211. 
Whiskey, 239. 
White nerve-matter, 158. 
White substance of Schwann, 159. 
Wholesome food, 78. 
Willis, circle of, 93. 
Wines, 237, 238. 
Work and worry, 171. 
Work of the heart, 91, 
Wormian hones, 27. 
Wounds, 110. 
X. 
Xiphoid appendage (Gr., sword-like), 10. 
Y. 
Yawning, 122. 
Yellow fever, 225. 
Yellow spot, 181,189. CONTENTS OF THE APPENDIX. 
PAGE 
1. To the Teacher 259 
2. What is Protoplasm? 260 
3. Classification of the Tissues 261 
4. Chemical Composition of the Human Bom ; . 263 
5. Table of Bones of the Cranium 266 
6. Table of Bones of the Face 267 
7. Table of Bones of the Trunk 268 
8. Table of Bones of the Limbs . 269 
9. Outline of Articulations 270 
10. Table of some Important Muscles 272 
11. The General Effect of Exercise on the Body 273 
12. The Effects of Over-exercise of the Muscles 274 
13. Amount of Work a Man may do 275 
14. Turning out the Toes 275 
15. The Foot and how it should be Treated 276 
16. Relative Strength of Men and Women 276 
17. The Use of Liquids at Meals 277 
18. Science and Economy in Cooking 277 
19. Coffee : A Physician’s View 277 
20. Hereditary Effects of Alcohol 278 
21. Blood Corpuscles #. . . 278 
22. Blood-plaques 279 
23. Carbon Dioxide in the Air 279 
24. The Finger Nails 279 
25. The Sudoriparous Glands 280 
26. The Distribution of Functions in the Cerebrum 280 
27. Brain Work and Insanity 282 
28. Relations of Mind and Body 282 
29. The Rate of Nerve Force : 283 
30. The Number of Nerve Cells and Fibers in the Brain . . . 284 
31. The Color Sense . 285 
32. The Arborescent Figure of Purkinje 285 
33. Hearing without Air 286 
34. The Germ Theory 286 
35. Longevity 287 
36. The Human Form 288 
37. Seat of the Greatest Growth 288 
38. Differences in the Male and Female Skeleton 288 
39. Compression of the Intervertebral Cartilages 289 
40. Anatomical Landmarks 290 
41. Disinfectants and their Use 291 
42. Comparative Anatomy 293 
43. Poisons and Antidotes 294 
44. Anatomy and Physiology of the Vocal Organs 297 APPENDIX. 
TO THE TEACHER. 
The teacher should always be in advance of the pupil, both in general 
grasp of the subject and in a knowledge of details. The former is, however, 
of more importance than the latter. It is always possible for some of the 
pupils, at least, to be better posted in some of the details of a subject than 
the teacher ; but in general knowledge, and in the comprehension of funda- 
mental principles and a knowledge of leading facts, the teacher should be 
much in advance of those he assumes to instruct. 
Few teachers have access to libraries rich in the literature of physiology, 
and no single text-book can contain that which will place the teacher in 
advance of the diligent pupil. This College Edition, containing matter in 
addition to the “ Lessons in Physiology,” has been prepared to meet, in part, 
the wants of the teacher. If possible, however, the teacher should possess 
at least one more comprehensive work. The author can confidently recom- 
mend as a valuable book for the teacher “ The Human Body,” by Prof. H. 
Newell Martin. It is not an expensive work, and will be found exceedingly 
helpful. 
A copy of the latest edition of Gray’s “ Anatomy ” would be a valuable 
reference book for the teacher. This, with Landois & Sterling’s “ Physi- 
ology ” and Parke’s “ Practical Hygiene,” would form a very complete library 
of reference in this line, but the expense of such books is considerable. Yet, 
many teachers can well afford them. 
The microscope is a valuable aid in the study of physiology. There are 
a great many teachers who could afford a microscope of sufficient powers to 
demonstrate all the important points of the subject. It must be remembered 
that microscopes range in price from 25 cents to hundreds of dollars. A 
simple lens, or common magnifying glass, costing no more than 25 cents, is 
of some value. It will answer in demonstrating adjustment of the eye, as 
shown in the text. The Excelsior pocket and dissecting microscope, costing 
only $2.50, will, under good management, show the individual corpuscles in 
the blood of the frog, and will easily show the circulation in the web of the 
frog’s foot. The lenses of this microscope can be used singly, and thus 
answer the purpose of a common magnifying glass. The Student’s micro- 
scope, with powers ranging from 80 to 375 diameters, can be had for $30.00. 
This will answer all pui'poses of the ordinary teacher, show structure of bone 
and teeth when sections are made thin enough, show human blood-corpuscles 
quite well, structure of muscles, epithelial cells, etc. There are other instru- 
ments that may answer the teacher’s purpose equally as well, but the price 
will not differ much from that we have named. The teacher should write 
for catalogues of microscopes of different houses, and compare prices and 
statements, or consult some reliable dealer in microscopes. 260 
APPENDIX. 
WHAT IS PROTOPLASM? 
In all modern works on plants and animals the term protoplasm is of fre- 
quent occurrence. Huxley called it “ the physical basis of life.” It is the 
first step in the organization of inorganic matter. It is living matter with- 
out definite shape. It is a very convenient term to use, but we really know 
but little about the substance it is the name of. We can say that protoplasm 
reproduces itself, drawing, in the case of the plant, from the inorganic world 
for its new material, and, in the case of the animal, from previously organ- 
ized matter. All protoplasm comes from some pre-existing protoplasm, 
which is equivalent to saying that all living things come from pre-existing 
living things. All tissues of plants and animals, with the exception of cer- 
tain crystalline and other mineral deposits between and in cells, are produced 
from protoplasm. 
“ A small lump of protoplasm may in itself represent an independent, liv- 
ing being, exhibiting vital phenomena of such a kind that it is impossible to 
refuse to call it an ‘ animal.’ It moves by its own force, and, as it would 
seem, voluntarily; it imbibes matter for its own nutrition from the sur- 
rounding liquid ; it grows, it multiplies its kind, and it dies. The most evi- 
dent motion in this case occurs in two ways. Sometimes single processes 
are seen to protrude from the whole mass ; these processes gradually affect 
the whole granular mass, so that the whole body is displaced, and a genuine 
change of position happens to the animal; or the processes being again 
retracted, other similar processes are protruded from another part of the 
body in such a way that the direction of motion is changed; in short, 
the animal creeps about on the glass plate on which it is observed by 
means of these processes. Meanwhile currents of granules can be seen 
within the mass; closer observation, however, shows that the motion in 
this case is only passive, and that it is the result of a continuous wave- 
like displacement of the protoplasm. Movements entirely similar to those 
in these independent animals (Amoebce) occur in more highly oi’ganized 
beings, vegetable as well as animal. All living beings are fundamentally com- 
posed of just such lumps of protoplasm as we see in the Amoebce. Most of these 
lumps of protoplasm have, however, essentially changed their appearance, 
and, at the same time, their qualities, so that it is only from the evolution 
of the parts that we know them to have originated from such lumps. More- 
over, even in developed organisms separate parts always occur which are in 
all respects similar to such lumps of protoplasm as the Amoebce, and which 
move like the latter. It is a well-known fact, that when a drop of blood is 
placed under the microscope, a very large number of small red bodies, to 
which the red color of the blood is due, are seen, within it. And scat- 
tered about among these red blood-corpuscles are seen colorless or white 
blood-corpuscles, round or jagged in form, and containing granular pro- 
toplasm with a kernel or nucleus. If the blood has been placed on a 
warmed glass, and if it is observed at a temperature of from 35 to 40 
degrees C., these blood-corpuscles exhibit active movements entirely similar 
to those of the Amoebce, and which have, therefore, been called Amoeboid 
movements. The corpuscles send out processes and again retract them; they 
creep about on the glass; and, in short, they behave exactly like Amoebce, 
and like the latter they even absorb matter, such as granules of any color- 
ing substance which may have been added, from the blood-fluid — they eat, 
that is, — and after a time they again reject this matter.”—Dr. 1. Rosenthal. 
Of plant protoplasm, Bessey, in his admirable work on Botany, thus APPENDIX. 
261 
speaks: “ If we examine a thin slice of any growing part of a plant under 
a microscope of a moderate power (100 to 500 diameters), there may be 
seen large numbers of cavities which are more or less filled with an almost 
transparent semi-fluid substance. In very young parts, as in buds and tips 
of roots, this substance entirely fills the cavities, and makes up almost the 
whole mass, while in older parts it occurs in less quantity, and usually 
disappears in quite old tissues. This substance is the living portion of the 
plant, the active, vital thing which gives to it its sensibility to heat, cold, 
and other agents, and the power of moving, of appropriating food, and of 
increasing in size; it is, in fact, that which is sensitive, which moves, appro- 
priates food, and increases in size. This sensitive, moving, assimilating, and 
growing substance is named Protoplasm. 
“It is a fact of great biological interest that in animals the essential 
constituent of all living parts is a substance similar to the protoplasm of 
plants. We cannot distinguish the two by any chemical or physical tests, 
and can only say that, taken as a whole, the protoplasm of plants differs 
from that of animals in its secretion. And yet these secretions are not 
strictly confined to plants; cellulose, starch, chlorophyll, and other products 
of vegetable protoplasm, formerly regarded as peculiar to plants, are now 
known to occur in undoubted animals. Botanists and zoologists have 
labored long in vain to discover absolute differences between the animal and 
the vegetable kingdoms ; between the higher plants and the higher animals 
there are great and constant differences; in none of the higher animals, for 
instance, is chlorophyll produced, but in the lower orders of both kingdoms 
not one of the differences observed to hold between the higher plants and 
animals exists.” 
Geddes, a recent investigator, thus defines protoplasm : — 
“ Protoplasm is regarded as an exceedingly complex and unstable com- 
pound, undergoing continual molecular chaqge or metabolism. On the one 
hand, more or less simple dead matter or food passes into life by a series of 
assimilative ascending changes, with each of which it becomes molecularly 
more complex and unstable. On the other hand, the resulting protoplasm 
is continually breaking down into more and more simple compounds, and 
finally into waste products. The ascending synthetic constructive series of 
changes are termed anabolic, and the descending disruptive series katabolic." 
CLASSIFICATION OF THE TISSUES. 
The following classification of tissues is based on that of William Turner, 
M.B., Professor of Anatomy, University of Edinburgh : — 
THE TISSUES. 
I. Cells suspended in Fluids. 
1. Blood. 
2. Lymph. 
3. Chyle. 
II. Cells placed on Free Surfaces. 
(“ By a free surface is meant a surface which is not blended with or at- 
tached to adjacent structures, but is free or separable from them without 
dissection. Every free surface is covered by one or more layers of cells.”) 
1. Epithelium. — (“ By the term epithelium is meant the cells situated 
on free surfaces which are exposed directly or indirectly to the air.”) 262 
APPENDIX. 
(1) Tessellated, pavement, scaly, or squamous. — Nucleated, flattened cells, 
varying in diameter from to of an inch. Found in mucous 
lining of mouth, pharynx, esophagus, conjunctiva, entrance to nasal cavity, 
and under the special name of epidermis forms the external layer of the skin. 
(2) Columnar, or Cylindrical. — Elongated, cylindrical cells, about 
of an inch long, placed side by side like palings, with their long axis per- 
pendicular to the surface on which they rest. Found in mucous lining of 
alimentary canal, and in the ducts of various glands. 
(3) Ciliated. — Columnar cells with hair-like processes or cilia, not more 
than xvooth to xoVo~th of an inch in length. Found in mucous lining of 
air passages, in ventricles of the brain, and canal of spinal cord, and some 
other places.1 
(4) Spheroidal, or Glandular. — Cells spheroidal or polyhedral in form. 
Found in glands and the commencement of gland ducts. 
(5) Transitional. — Forms of cells resembling both columnar and tessel- 
lated, 'or columnar and spheroidal. The cells of the mucous membrane of 
the bladder are of this nature. 
2. Endothelium. —(“ By the term endothelium is meant the cells situated 
on free surfaces which are not exposed directly or indirectly to the air.”) 
Generally flattened,, scale-like cells, arranged like the cells of tessellated 
epithelium. Found in all serous membranes. 
III. Cells embedded in Solid Tissues. 
1. Connective Tissue. — Those tissues which, though differing in various 
respects from each other, agree in having the property of binding together 
other tissues or parts of the body, and in serving as a supporting framework 
for more delicate tissues. 
(1) Neuroglia. — “ Small round or ovoid corpuscles, embedded in a soft 
undifferentiated protoplasm.” Connects the nerve-cells and nerve-fibers. 
(2) Retiform Tissue. — Star-shaped, branching cells. It constitutes the 
supporting framework of the lymphatic and some other glands, also in the 
enamel the teeth. 
(3) Gelatinous or Mucous Tissue. — The framework of the vitreous 
humor of the eye. Rounded or star-shaped cells, embedded in a gelatinous 
substance. 
(4) Fibrous Tissue. — Consisting of threads or fibers. 
a. Areolar Tissue. — Loose, fine fibers, running in all directions. Found 
just below the skin and in part of the peritoneum. 
b. White Fibrous Tissue. — Makes up the great bulk of most ligaments, 
tendons, and fibrous membranes. The fibers are extremely delicate, 2viyoo4h 
to of an inch in thickness. 
c. Yellow Fibrous Tissue. —Elastic fibers, certain ligaments as the strong 
ligament in the back of the neck (ligamentum nuchce), and in the elas- 
tic coats of the arteries. In some places mingled with the white fibrous 
tissue. 
2. Adipose Tissue. — Collections of ovoid or spherical cells containing 
fat. 
3. Pigmentary Tissue. — Cells containing coloring-matter. Found in 
the skin and choroid coat of the eye. 
4. Cartilaginous Tissue. — (“ By the term cartilage or cartilaginous tis- 
sue is meant a group of tissues which, although usually found in the form 
1 The ciliated cells of the ventricles of the brain and spinal cord would properly 
come under the head of endothelium, as they are not exposed to air. APPENDIX. 
263 
of plates or bars, yet differ in various aspects from each other, both in 
naked eye and microscopic characters. They agree, however, in forming 
solid textures, opaque when seen in mass, but in thin slices translucent, 
pearly, or bluish white, firm in consistence, but easily cut with a knife, 
endowed with considerable elasticity, and yielding chondrine on boiling.”) 
(!) Cellular Cartilage. — The original form of bone, the growth of bone 
being the change or modification of the cartilage cells into bone cells. 
(2) Hyaline Cartilage. — Cells embedded in semi-transparent, solid mass. 
The costal cartilages, the layer at euds of bones, those of the nose and 
trachea and part of those in the larynx, also the temporary cartilage. 
(3) Fibro-cartilage. — Cartilage cells and fibrous tissue commingled. 
The epiglottis, framework of the external ear, Eustachian tube, etc. 
5. Osseous Tissue. 
6. Muscular Tissue. 
7. Nervous Tissue. 
Have been sufficiently described. 
CHEMICAL COMPOSITION OF THE HUMAN BODY. 
Note. — The teacher who has some knowledge of chemistry may make 
the following outline the basis of an hour’s lecture or talk on this subject. 
If possible, specimens of some of the elements should be exhibited. The 
following may be obtained without cost in a state nearly pure: — Carbon 
in the form of charcoal, black lead, and gas carbon (the latter is used in 
electric batteries and electric lights); sulphur, iron, fibrin, glucose, gelatine, 
calcium carbonate in the form of limestone and marble, sodium chloride 
(common salt). The following may be purchased at a small cost: — Phos- 
phorus, magnesium, sodium, potassium, dextrin, calcium phosphate, cal- 
cium fluoride. The following may be manufactured by the teacher who 
has studied chemistry, and their peculiar properties illustrated by experi- 
ments : — Hydrogen, oxygen, nitrogen, chlorine. 
I. Ultimate Elements. — By these, we mean those elements which cannot 
be further divided or separated into two or more elements. 
1. Carbon. — Found in all the tissues of the body. Found pure in 
nature as the diamond, and nearly so as charcoal, anthracite coal, graphite, 
or black lead. Produced in the manufacture of illuminating gas from coal. 
Combined in limestone, marble, and chalk, and in all animal and vegetable 
substances. 
2. Hydrogen. —In all the tissues. When free and uncombined it is an 
invisible, inflammable gas, the lightest of all known substances. One of the 
elements of water and consequently of all animal and vegetable substances. 
3. Oxygen. — In all the tissues. When uncombined it is a gas sixteen 
times as heavy as hydrogen, a little heavier than air. Does not burn but 
most substances burn readily in it; in fact, nearly all combustion or burning 
is simply the union of oxygen with some other substances so rapidly that 
great heat is produced. Nearly all decay is also the union of oxygen with 
some of the elements of a substance, but more slowly than in combustion. 
Found in the air simply mixed, not chemically combined with nitrogen. 
One of the elements of water. It is combined in nearly every substance in 
nature. 
4. Nitrogen. —In most all of the tissues. When uncombined, it is a gas 
which will not burn nor support combustion nor life. It is free in the air. 
Combined with hydrogen it forms ammonia, and with hydrogen and 264 
APPENDIX. 
oxygen, nitric acid and numerous acids and salts, including a number of 
highly explosive substances. 
5. Sulphur. — One of the elements of albumen and fibrin. Also found 
in the hair, epidermis, and nails. Hair is dyed black by salts of silver, 
because the sulphur in the hair unites with the silver to form silver sulphide, 
a black substance. For the same reason a drop of nitrate of silver makes a 
black spot on the skin which will not wash out, but remains until the 
epidermis is cast off and replaced by new. Eggs blacken silver spoons on 
the same principle. Sulphur is found in nature in an uncombined state 
in volcanic regions, and is widely diffused in the form of combinations 
with iron and copper. 
6. Phosphorus. —Found in bones and nerves. When uncombined is a 
solid, waxy substance, which takes fire at a temperature a little higher than 
that of the body. Must be handled with extreme care, as a little friction 
will cause it to ignite. Does not exist uncombined in nature. Is manu- 
factured mainly from the bones of animals. 
7. Calcium. — Found in the bones. In nature it is never found uncom- 
bined, but is very abundant and widely diffused, being one of the elements 
of limestone, which is the commonest of rocks. It is a light yellow metal. 
8. Magnesium. — In the bones in small quantities. In nature combined 
with other elements in various rocks and soils. When uncombined it is a 
white metal, which takes fire at a red heat, and burns with the most brilliant 
and intense light. 
9. Sodium. — Found in minute proportions in every tissue of the body, 
and in almost every substance in nature. When separated from its combina- 
tions by the chemist it is a white metal, soft as wax, and when it comes in 
contact with water it appears to take fire and burn with a yellow flame. In 
reality it unites with the oxygen of the water, releasing the hydrogen, which 
burns as it is released. 
10. Potassium. — Found in muscles and some other parts of the body. 
Abundant in the ashes of plants. Resembles sodium in its properties, behav- 
ing when thrown on water in a similar manner, except that the flame is 
violet. 
11. Chlorine. — Found generally combined with sodium in the form of 
chloride of sodium, or common salt, in nearly all the tissues. When uncom- 
bined it is a heavy, greenish gas, very irritating and poisonous. 
12. Fluorine. — In minute quantities in bones and teeth. Sparingly dis- 
tributed in nature. It is the only element which will not unite with oxygen. 
Until recently chemists did not succeed in isolating it. 
13. Silicon. — Exists in minute quantities in the brain. Found more 
abundantly in plants, and exceedingly abundant in nature in the form of 
silica or quartz, which is a compound of oxygen and silicon. 
14. Iron. — Sparingly in the heinaglobin of the red corpuscles of the 
blood. 
15. Manganese. — In minute quantity in bones. When uncombined it 
is a hard, white metal. 
II. Proximate Elements. 
By proximate elements is meant those compounds produced by the 
chemical union of two or more ultimate elements. For example, water is a 
proximate element consisting of hydrogen and oxygen; common salt is a 
proximate element consisting of chlorine and sodium. We can give a brief 
notice of only the most important ones here. It must be remembered that 
when we speak of a proximate element of the body we mean one that is APPENDIX. 
265 
found in the living tissues, or may be separated from them immediately after 
the death of the part. There are many compounds formed, as we observed 
in the introduction to this volume, during the decay of the body. These 
must not be considered as normal constituents of the tissues. We cannot 
say that alcohol exists in corn or apples, but it is produced from the elements 
contained in these vegetables during their decomposition. The important 
proximate elements may be classified as follows : 
1. Nitrogenous or Albuminous Substances. 
(1) Proteids or Albuminoids. — Under this head are grouped various 
substances which contain carbon, oxygen, hydrogen, and nitrogen (with 
sometimes other elements, as phosphorus), in varying proportion. 
a. Serum-Albumen. — The principal form of albumen in the body. Found 
in the blood and in the muscles. 
b. Casein. — In milk. 
c. Myosin. — The principal part of dead muscle. 
d. Fibrin. — May be separated from fresh blood by whipping it with 
twigs. Is formed in coagulation of the blood; in fact, coagulation is nothing 
more nor less than the formation of fibrin from the elements of living blood. 
e. Peptone or Albuminose.— The various albuminous substances which 
are taken as food are converted into a soluble form by the action of the 
digestive fluids, this soluble form being called peptones. (See Discussion of 
Processes of Digestion.) 
(2) Substances resembling Proteids. 
a. Mucine. — The active principle of mucus. 
b. Chondrin. — The principal basis of cartilage. 
c. Gelatine. — Obtained by boiling fibrous tissue, as tendons and liga- 
ments ; also from the skin and bones. The jelly of pigs’ feet is pure gelatine. 
Glue is dried gelatine. 
2. Carbonaceous Substances. — Substances which contain carbon, 
hydrogen, and oxygen, but no nitrogen. They differ from nitrogenous sub- 
stances in being less liable to decay. 
(1) Carbo-hydrates. — Those in which the carbon predominates. 
a. Glucose, or Grape-sugar. — Produced in the liver from glycogen. 
Found in the blood. An excess of glucose in the body forms the disease 
known as diabetes. 
b. Lactose, or Milk-sugar. — Found in milk. 
c. Dextrin. — A substance produced from starch by the action of fer- 
ments. It is a step in the process of converting starch to glucose. It is 
found in the alimentary canal after a meal containing starch, and has also 
been found in the blood. 
d. Glycogen. — Found in the liver if examined immediately after death; 
but if much delay, it is all converted into glucose. See Functions of the 
Liver. 
(2) Hydro-carbons. — Those substances in which the hydrogen predomi- 
nates. They are represented by the fat of the body. 
3. Inorganic Substances. — This includes all substances which are not 
peculiar to animal and vegetable bodies, but found in the mineral kingdom 
also. 
(1) Water. — This has been sufficiently described. See Index to body 
of book for the various places in which it is discussed. 
(2) Calcium Phosphate. — More commonly known as phosphate of lime, 
a principal constituent of bones. 
(3) Calcium Carbonate. — Known in the mineral kingdom as limestone, 
marble, and carbonate of lime. Found in bones. 266 
APPENDIX. 
(4) Calcium Fluoride. — Known in the mineral kingdom as fluor-spar. 
It is found only in small quantities in bones and in teeth. 
(5) Sodium Chloride. — Commonly known as common salt. In the 
blood and perspiration; also in nearly all the tissues of the body in small 
proportion. 
TABLE OF BONES OF THE CRANIUM. 
Name. 
Articulates with. 
Muscles attached. 
Uses, etc. 
Occipital 
Two parietal 
Two temporal . 
Sphenoid 
Atlas 
Twelve pairs—Occipito- 
frontalis, trapezius, 
and others 
Forms hack and 
base of skull 
Frontal 
Two malar 
Two parietal 
Sphenoid 
Ethmoid 
Two nasal 
Two superior maxillary 
Two lachrymal 
Three pairs — Corruga- 
tor supercilii, orbic- 
ularis palpebrarum, 
temporal 
Forms forehead. 
In two pieces at 
birth, which usu- 
ally unite after- 
ward 
Temporal 
Occipital 
Parietal 
Sphenoid 
Inferior maxillary 
Malar 
Fifteen pairs — Tem- 
poral, masseter, oc- 
cipito-frontalis, and 
others 
Forms side and 
base of skull, 
and contains in- 
ternal ear 
Parietal 
Opposite parietal 
Occipital 
Frontal 
Temporal 
Sphenoid 
Only one — The tem- 
poral 
Forms side and top 
of skull 
Sphenoid 
All others of cranium, 
and — 
Two malar 
Two palate 
Vomer 
Twelve pairs — Tem- 
poral, external and 
internal pterygoid, 
muscles of eyeball, 
and others 
Forms base of 
skull, holds 
others together 
Ethmoid 
Sphenoid 
Frontal 
Two nasal 
Two superior maxillary 
Two lachrymal 
Two inferior turbinated 
Vomer 
No muscles attached 
Helps to form 
orbits, transmits 
olfactory nerve APPENDIX. 
267 
TABLE OF BONES OF THE FACE. 
Name. 
Articulates with. 
Muscles attached. 
Uses, etc. 
Nasal 
Frontal 
Ethmoid 
Opposite nasal superior 
maxillary 
No muscles attached 
Forms bridge of 
nose 
Superior 
maxillary 
Frontal 
Ethmoid 
Nasal 
Malar 
Lachrymal 
Inferior turbinated 
Palate 
Vomer 
Opposite superior max- 
illary 
Twelve pairs — Orbicu- 
laris palpebrarum, 
buccinnator, masse- 
ter, and others 
Forms upper jaw. 
Contains upper 
teeth 
Palate 
Sphenoid 
Ethmoid 
Superior maxillary 
Inferior turbinated 
Vomer 
Opposite palate 
Five — Internal and ex- 
ternal pterygoid, su- 
perior constrictor of 
pharynx, tensor pa- 
lati,and azygos uvulae 
Forms hack part 
of roof of mouth 
Lachrymal 
Frontal 
Ethmoid 
Superior maxillary 
Inferior turbinated 
One muscle — Tensor 
tarsi 
Helps to form orbit 
Malar 
Frontal 
Sphenoid 
Temporal 
Superior maxillary 
Five — Masseter, tem- 
poral, and others 
Helps form orbit 
and prominence 
of cheek 
Inferior 
turbinated 
Ethmoid 
Superior maxillary 
Lachrymal 
Palate 
No muscles attached 
Furnishes surface 
for spread of ol- 
factory nerve 
Inferior 
maxillary 
Two temporal 
Fifteen pairs — Buccin- 
nator, masseter, di- 
gastric, temporal, in- 
ternal and external 
pterygoid, and others 
Lower jaw. Con- 
tains lower teeth. 
Largest hone of 
face 
Vomer 
Sphenoid 
Ethmoid 
Two superior maxillary 
Two palate 
No muscles attached 
Forms septum of 
nasal cavity 268 
APPENDIX. 
TABLE OF BONES OF THE TRUNK. 
Name. 
Abticulates with. 
Muscles attached. 
Uses, etc. 
Sternum 
Clavicles 
Seven costal cartilages 
on each side 
Nine pairs and one 
single muscle—Pecto- 
ralis major, sterno- 
cleido-mastoid, dia- 
phragm, and others 
Forms part of front 
wall of thorax. 
Holds ribs in 
place 
Ribs 
Each with one or a part 
of two vertebrae, and 
all except 11th and 
12th with costal carti- 
lages 
Twenty — Internal and 
external pterygoid, 
pectoralis major, dia- 
phragm, and others 
Form the main part 
of the thorax. 
Aid in breathing 
Clavicle 
Sternum 
Scapula 
Cartilage of 1st rih 
Seven—Trapezius, ster- 
no-cleido-mastoid,del- 
toid, and others 
Acts as a brace to 
shoulder 
Scapula 
Humerus 
Clavicle 
Eighteen — Trapezius, 
deltoid, biceps, tri- 
ceps, and others 
Forms the shoul- 
der. Attaches 
arm to body 
Atlas 
Occipital axis 
Nine pairs — Longus 
colli, levator anguli 
scapulae, and others 
Supports the head 
Axis 
Atlas 
Third cervical vertebra 
Eleven pairs — Muscles 
of neck and back 
The pivot on which 
the head rotates 
Other verte- 
brae 
Axis 
Sacrum 
Ribs 
Thirty-five pairs and 
one single muscle 
Form the axis of 
the body and 
protect spinal 
cord 
Sacrum 
Last lumbar vertebra 
Coccyx 
Two innominata 
Eight pairs — Gluteus 
maximus, latissimus 
dorsi, and others 
Forms back wall of 
pelvis 
Coccyx 
Sacrum 
Four pairs and one 
single muscle — Glu- 
teus maximus and 
others 
Gives attachment 
to muscles — not 
important in man 
Os innomi- 
natum 
Its fellow 
Sacrum 
Femur 
Forty-five muscles of 
abdomen, back, thigh, 
and pelvis 
Forms main part of 
pelvis. Attaches 
lower limb to 
trunk APPENDIX. 
269 
TABLE OF BONES OF THE LIMBS. 
Name. 
Articulates with. 
Muscles attached. 
Uses, etc. 
Humerus 
Scapula 
Ulna 
Radius 
Twenty-five — Pectora- 
lis major, latissimus 
dorsi, deltoid, flexors 
and extensors of the 
forearm, and others 
The axis of the 
upper arm 
Ulna 
Humerus 
Radius 
Sixteen — Triceps, an- 
coneus, flexors and 
extensors of fingers, 
and others 
Forms main joint 
at elbow. With 
radius makes 
forearm 
Radius 
Humerus 
Ulna 
Scaphoid 
Semilunar 
Nine — Biceps, flexors, 
extensors, pronators 
and supinators of 
hand 
Forms main joint 
at wrist. With 
ulna makes fore- 
arm 
Carpal bones 
Radius 
Metacarpal bones 
Seven — Short flexors 
of the fingers 
Form an elastic 
union of hand to 
arm, by the aid 
of ligaments 
Metacarpal 
bones 
Carpal bones 
Phalanges 
Twenty-one — Flexors 
and extensors of the 
hand 
Form the frame- 
work of the hand 
Phalanges of 
hand 
Metacarpal hones 
Fellows 
Twenty-one — Flexors 
and extensors of the 
fingers 
The axes of the 
fingers 
Femur 
Os innominatum 
Tihia 
Patella 
Twenty-three —Gluteus 
maximus, crureus, 
gastrocnemius, plan- 
taris, and others 
The axis of the 
thigh 
Patella 
Femur 
Four muscles having 
one common tendon 
— Rectus, crureus, 
vastus internus, vas- 
tus externus 
Protects knee joint 
Tibia 
Femur 
Fibula 
Astragalus 
Twelve — Tibialis an- 
ticus, sartorius, grac- 
ilis, and others 
The main axis of 
the leg 
Fibula 
Tibia 
Astragalus 
Nine — Biceps femoris, 
soleus, and others 
An aid to the tibia 
Astragalus 
Tibia 
Fibula 
Os calcis 
Scaphoid 
No muscles attached 
Supports the tibia. 
Main part of 
ankle joint 
Os calcis or 
caleaneum 
Astragalus 
Cuboid 
Eight — Tendo Achillis, 
plantaris, and others 
Forms the support 
of the heel 270 
APPENDIX. 
TABLE OF BONES OF THE LIMBS. — Continued. 
Name. 
Articulates with. 
Muscles attached. 
Uses, etc. 
Cuboid 
Os calcis 
External cuneiform 
4th metatarsal hone 
5th metatarsal hone 
Sometimes with sca- 
phoid. 
Part of the flexor brevis 
pollicis 
Helps form the in- 
step 
Scaphoid 
Astragalus 
Three cuneiform 
Sometimes with cuboid 
Part of tibialis posticus 
Helps to form in- 
step 
Three cunei- 
form hones 
Scaphoid 
Cuboid 
1st, 2d, 3d, and 4th 
metatarsal hones 
Tibialis posticus and 
anticus, flexor brevis 
pollicis 
Help form instep 
Metatarsal 
hones 
Tarsal bones 
Phalanges 
Twenty-one muscles 
. .. 
Form the frame- 
work of the front 
part of foot 
Phalanges 
Metatarsal hones 
Fellows 
Twenty-four muscles — 
Flexors and extensors 
of the toes 
Axes of the toes 
ARTICULATIONS. 
The following outline is adapted from Gray’s “ Anatomy.” 
I. Kinds of Joints. 
1. Synarthrosis, or Immovable Joint. — Surfaces separated by fibrous 
membrane, without any intervening synovial cavity, and immovably con- 
nected with each other, as in joints of cranium and face (except lower jaw). 
(1) Sutura. — Articulation by processes and indentations interlocked 
together. 
a. Sutura vera (true). — Articulate by indented borders. 
(a) Dentata. — Having tooth-like processes, as in interparietal suture. 
(b) Serrata. — Having serrated edges, like the teeth of a saw, as in inter- 
frontal suture. 
(c) Limbosa. — Having bevelled margins and dentated processes, as in 
fronto-parietal suture. 
b. Sutura notha (false).— Articulate by rough surfaces. 
(a) Squamosa.— Formed by their bevelled margins overlapping each 
other, as in squamo-parietal suture. 
(b) Harmonia. — Formed by the apposition of contiguous rough surfaces, 
as in intermaxillary suture. APPENDIX. 
271 
(2) Schindylesis. — Articulation formed by the reception of a thin plate 
of one bone into a fissure of another, as in articulation of sphenoid with 
vomer. 
(3) Gomphosis. — Articulation formed by the insertion of a conical 
process into a socket, as the teeth. 
2. Amphiarthrosis, or Mixed Articulations. 
(1) Surfaces connected by fibro-cartilage, not separated by synovial 
membrane, and having limited motion, as in joints between bodies of 
vertebrae. 
(2) Surfaces covered by fibro-cartilage, lined by a partial synovial mem- 
brane, as in sacro-iliac and pubic joints. 
3. Diarthrosis, or Movable Joint. 
(1) Arthrodia, or Gliding Joint.— Articulation by plane surfaces, which 
glide upon each other, as in sterno-clavicular joint. 
(2) Enarthrosis, or Ball-and-Socket Joint. — Articulations by a globular 
head received into a cup-like cavity, as in hip and shoulder joints. 
(3) Ginglymus, or Hinge Joint. — Articulation surfaces fitted together so 
as to permit motion in one plane, as in elbow, ankle, and knee. 
(4) Diarthrosis Rotcitorius, or Lateral Ginglymus. — Articulation by a 
pivot process, turning within a ring or ring round a pivot, as between upper 
end of radius and ulna and the atlo-axoid joint. 
(5) Condyloid. — Ovoid head received into elliptical cavity, as the wrist 
joint. 
(6) Reciprocal Reception. — Articular surfaces inversely convex in one 
direction and concave in the other, as in the metacarpo-phalangeal joint of 
the thumb. 
II. Kinds of Movement admitted in Joints. 
1. Gliding. — Common to all movable joints; but in some, as in the car- 
pus and tarsus, it is the only motion permitted. 
2. Angular. — Occurs only in long bones, and by it the angle between 
the two bones is increased or diminished. It may take place in foul- 
directions,— forward and backward, constituting flexion and extension, or 
inward and outward, constituting adduction and abduction. The ginglymoid 
joints admit of motion in two directions only. 
3. Circumduction. — Where the extremity of the bone is made to 
describe a circle, or the whole length of the limb describes a conical space, 
having the joint as the apex; the shoulder and hip joints are capable of 
this motion. 
4. Rotation. — The movement of a bone on its own axis, as in the atlas 
and axis, and the radius and humerus. 272 
APPENDIX. 
TABLE OF SOME IMPORTANT MUSCLES. 
Note. — “ In the description of a muscle the term origin is meant to imply its more [usually] 
fixed or central attachment, and the term insertion the movable point to which the force of the 
muscle is directed; but the origin is absolutely fixed in only a very small number of muscles, 
such as those of the face, which are attached by one extremity to the bone, and by the other to 
the movable integument. In the greater number the muscle can be made to act from either 
extremity.” — Gray's "Anatomy." 
Name. 
Origin. 
Insertion. 
Action. 
Shape, etc. 
Occipito-frontalis 
Occipital bone 
Skin of fore- 
head 
Raises the eye- 
brows and moves 
scalp 
Broad, thin, and 
tendinous 
Orbicularis 
palpebrarum 
Interior angle of 
frontal bone 
mainly 
Makes com- 
plete ring and 
blends with 
other muscles 
Closes the eyes 
Sphincter muscle 
Corrugator 
supercilii 
Interior angle of 
frontal bone 
Into the orbic- 
ularis palpe- 
brarum 
Draws eyebrow 
down and in. 
“ The frowning 
muscle ” 
Pyramidal, small 
Temporal 
Temporal, parietal, 
and frontal bones 
Lower jaw 
Raises lower jaw 
Radiating 
Masseter 
Superior maxillary 
and malar bones 
Lower jaw 
Raises lower jaw 
Short, thick, quadri- 
lateral 
External and in- 
ternal ptery- 
goid 
Sphenoid and pal- 
ate bones 
Lower jaw 
Give side motion 
to lower jaw. 
“Food-grinders” 
Short and thick 
Platysma 
myoides 
Clavicle and scap- 
ula 
Lower jaw 
Draws jaw, lip, and 
corner of mouth 
down. Expresses 
melancholy 
Very thin and 
broad 
Sterno-cleido- 
mastoid 
Sternum and clav- 
icle 
Mastoid proc- 
ess of tem- 
poral bone 
One turns head to 
one side. Both 
together bend 
head down. 
Shortening of it 
produces “wry- 
neck ” 
Thick in the mid- 
dle, flattened at 
ends 
Digastric 
Temporal bone, 
front of mastoid 
process 
Lower jaw at 
chin 
Lowers the jaw 
and raises hyoid 
bone in swallow- 
ing 
Two parts. Tendon 
in middle, which 
perforates stylo- 
hyoid 
Stylo-hyoid 
Styloid process of 
temporal bone 
Hyoid bone 
Raises hyoid bone 
in swallowing 
Slender, perforated 
by digastric 
Pectoralis major 
Clavicle, sternum, 
and costal carti- 
lages 
Humerus 
Draws arm across 
chest. The “ fly- 
ing muscle ” in 
birds 
Triangular, radiat- 
ing 
Trapezius 
Occipital bone and 
spinal column 
Clavicle and 
scapula 
Raises shoulder 
and draws it back 
Triangular, broad 
Latissimus dorsi 
Dorsal, lumbar, 
and sacral verte- 
brae 
Humerus 
Draws arm back 
and down 
Broad and flat APPENDIX. 
273 
TABLE OF SOME IMPORTANT MUSCLES. — Continued. 
Name. 
Origin. 
Insertion. 
Action. 
Shape, etc. 
Serratus posticus 
superior 
Cervical and dorsal 
vertebrae 
2d, 3d, 4th, and 
5th ribs 
Elevates the ribs. 
An inspiratory 
muscle 
Thin, flat, quadri- 
lateral 
Serratus posticus 
inferior 
Dorsal and lumbar 
vertebrae 
9th, 10th, 11th, 
and 12th ribs 
Draws ribs down 
Quadrilateral 
Erector spinse 
Sacral, lumbar, and 
dorsal vertebrae 
Ribs and cer- 
vical vertebrae 
Maintains erect po- 
sition of spinal 
column 
Large mass below, 
several divisions 
above 
Deltoid 
Scapula and clav- 
icle 
Humerus 
Raises the arm 
Thick, triangular 
Teres major 
Scapula 
Humerus 
Lowers the arm 
Slightly flattened 
Subscapularis 
Scapula 
Humerus 
Rotates the arm 
inward 
Triangular 
Biceps (of arm) 
Scapula 
Radius 
Bends the arm at 
elbow 
Fusiform 
Triceps 
Scapula and upper 
end of humerus 
Ulna 
Straightens the 
arm. Antagonist 
of biceps 
Three - parted at 
upper end 
Psoas magnus 
Last dorsal and all 
the lumbar verte- 
brae 
Upper end of 
the femur 
Bends the thigh on 
the body 
Fusiform 
Gluteus maximus 
Ilium, back part 
Upper end of 
femur 
Straightens and ro- 
tates the thigh 
outward 
Quadrilateral. One 
of the largest in 
the body 
Biceps (of leg) 
Ischium and femur 
Fibula and 
tibia 
Bends the leg at 
knee 
Fusiform 
Quadriceps ex- 
tensor 
Ilium and femur 
Patella 
Straightens the leg. 
The antagonist 
of biceps 
Four muscles with 
one tendon at 
lower end 
Gastrocnemius 
Lower end of femur 
Os calcis 
Raises the heel and 
with it the entire 
body 
“ Calf of leg.” Its 
tendon is the 
“ tendon of Achil- 
les ” 
The diaphragm 
Lumbar vertebrae, 
ribs, and ster- 
num 
A flat tendon 
in the center 
Principal agent in 
breathing 
Flat and thin 
THE GENERAL EFFECT OF EXERCISE ON THE BODY, 
The main effect of exercise is to increase oxidation of carbon and per- 
haps also of hydrogen. It also eliminates water from the body; and this 
action continues, as seen from Pettenkofer and Voit’s experiments, for some 
time. After exercise, therefore, the body is poorer in water, especially the 
blood. It increases the rapidity of circulation everywhere, as well as the 
pressure on the vessels; and therefore it causes in all organs a more rapid 
outflow of plasma and absorption, — in other words, a quicker renewal. In 274 
APPENDIX. 
this way also it removes the products of their action to the various parts of 
the body. It increases the outflow of warmth from the body by increasing 
perspiration. It therefore strengthens all parts. It must be combined with 
increased supply, both of nitrogen and carbon (the latter possibly in the 
form of fat), otherwise the absorption of oxygen, the molecular changes in 
the nitrogenous tissues, and the elimination of carbon will be checked. 
There must be also an increased supply of salts, certainly of chloride of 
sodium, probably of potassium phosphate and chloride. There must be 
proper intervals of rest, or the store of oxygen, and the material in the 
muscles which is to be metamorphosed during contraction, cannot take 
place. The integrity and perfect freedom of action, both of the lungs and 
heart, are essential; otherwise neither absorption of oxygen nor elimination 
of carbon can go on, nor can the necessary increased supply of blood be 
given to the acting muscles without injury. — Parkes’s “Practical Hygiene.” 
EFFECTS OF OVER-EXERCISE OF THE MUSCLES. 
Physiology teaches us that the contraction of the muscle is attended with 
the production of various chemical substances, such as carbonic acid, lactic 
acid, urea, creatin, sugar, phosphates, etc. In the normal state these waste 
matters — the ashes of the fire of life — are easily got rid of by the kidneys, 
lungs, and other organs, which play the part of dustmen to the economy. 
The greater the work done, the larger naturally is the amount of waste 
matter produced ; and, if the work is increased beyond a certain point, the 
physiological dust-bin becomes full faster than it can be emptied. In that 
case the waste matters accumulate in the muscles and give rise to the feeling 
of fatigue ; indeed, fatigue can be artificially induced by injecting into the 
muscles of a perfectly fresh animal an “ extract ” of the muscles of another that 
is tired out. In healthy persons a comparatively short period of rest suffices 
for the removal of the waste matters, and fatigue disappears. 
It may be said here that this happy result is much assisted by allowing 
young athletes a sufficient amount of sleep, as in addition to the repose 
afforded to the muscles thereby during sleep there is much less formation of 
poisonous material that causes fatigue than in the waking state. Hence 
sleep is a particularly favorable condition, for the “ working off ” of the 
poisons generated during exercise. 
If, however, the work to be done is too severe or too prolonged, the elimi- 
nation of waste matters cannot keep pace with their production, the system 
becomes saturated with them, and “ auto-intoxication ” results, the man being 
in truth poisoned by materials of his own manufacture. The dose may be 
sufficient to cause death, as in the case, reported by Dr. Bertherand, of two 
native runners in Algiers, who died immediately after having run respectively 
192 kilometers in forty-five hours, and 252 kilometers in sixty-two hours. On 
examination of the bodies nothing was found beyond the ordinary signs of 
excessive fatigue (intense blackness of the blood, owing to deficient aeration, 
great softening and discoloration of the muscles, extravasation of blood in 
various parts of the skin and mucous membrane with extremely rapid decom- 
position). 
It is now coming to be recognized that many of the cases of so-called 
“sunstroke” among soldiers on the march are really due to the “auto- 
intoxication ” by waste products which I have described. — Sir Morell Mac- 
kenzie, M.D. APPENDIX. 
275 
The external work which can be done by a man daily has been estimated 
at one-seventh of the work of the horse; but if the work of a horse is con- 
sidered to be equal to the one-horse power of a steam-engine (viz., 33,000 lbs. 
raised one foot high per minute, or 8839 tons raised one foot high in ten 
hours), this must be an over-estimate, as one-seventh of this would be 1263 
tons raised one foot in a day’s work of ten hours. In some works on 
physiology a man’s work of eight hours has been put as high as 1020 tons 
lifted a foot; but this is far too much. The hardest day’s work of twelve 
hours noted by Dr. Parkes was in the case of a workman in a copper rolling 
mill. He stated that he occasionally raised a weight of 90 lbs. to a height 
of eighteen inches 12,000 times a day. Supposing this to be correct, he 
would raise 723 tons one foot high. But this much overpasses the usual 
amount. The same man’s ordinary day’s work, which he considered ex- 
tremely hard, was raising a weight of 124 lbs. sixteen inches, 5000 or 6000 
times in a day. Adopting the larger number, this would make his work 
equivalent to 442.8 tons lifted a foot, and this was a hard day’s work for a 
powerful man. Some of the puddlers in the iron country and the glass- 
blowers probably worked harder than this, but there are no calculations 
recorded. From the statement of a pedler, his ordinary day’s work was to 
carry 28 lbs. twenty miles daily. The weight is balanced over the shoulder 
—14 lbs. behind and 14 lbs. in front. The work is equal to 419.5 tons lifted 
one foot. It would, therefore, seem certain that an amount of work equal 
to 500 tons lifted a foot is an extremely hard day’s work, which perhaps few 
men could continue to do. Four hundred tons lifted a foot is a hard day’s 
work, and 300 tons lifted a foot is an average day’s work for a healthy, strong 
adult. 
The external work is thus 300 to 500 tons on an average; the internal 
work of the heart, muscles of respiration, digestion, etc., has been variously 
estimated ; the estimates for the heart alone vary from 122 to 277 tons lifted 
a foot. The former is that given by Haughton, who estimates the respiratory 
movements as about 11 tons lifted a foot in twenty-four hours. Adopting a 
mean number of 260 tons for all the internal mechanical work, and the ex- 
ternal work of a mechanic being 300 to 500 tons, this will amount to one- 
seventh to one-eighth of all the force obtainable from food. — Parkes's 
“ Practical Hygiene.” 
AMOUNT OF WORK A MAN MAY DO. 
The practice of turning out the toes, so much insisted on by dancing- 
masters, when it becomes habitual is a deformity. Although in standing in an 
easy position the whole limb may be rotated outward from the hip, so as to 
give a broader basis of support, in walking or running the hip, knee, ankle, 
and joints of the foot are simple hinges, and it is essential for the proper co- 
ordination of their actions that they should all work in the same plane, 
which can only be the case when the toes are pointed directly forward and 
the feet nearly parallel to one another. Any deviation from this position 
must interfere with the true action of the foot when raising and propelling 
the body. Turning out the toes is, moreover, a common cause of ■weak 
ankles, as it throws the weight of the body chiefly on the inside, instead of 
distributing it equally over all parts of the joint. — William Henry Flower, 
LL.D., F.R.S. 
TURNING OUT THE TOES. 276 
APPENDIX. 
THE FOOT AND HOW IT SHOULD BE TREATED. 
The human foot is an instrument admirably adapted to all the various 
uses it has to serve, which fashion has done its best to spoil by improper 
treatment. The bones of the instep are so adjusted as to form an arrange- 
ment which combines in exquisite perfection the resistance of the arch with 
as much elasticity as enables it to bear safely the prodigious strain to which 
it is subjected. The whole frame of the foot is kept in position and made 
capable of its proper range of movement by means of muscles and tendons, 
constituting a living and sensitive bandage, increasing or relaxing its pull or 
pressure in the most exact obedience to our will. In a sound, free foot each 
part of the machinery is in constant readiness to bring it into the required 
position, whether to lift the body, to bound, or to sustain the shock of the 
whole weight in coming down again, or to perform any other of a number of 
complications of movement. 
How perfectly the foot is adapted for these purposes and is protected 
against too great pressure and sudden shock is showm by the fact that such 
violent actions as leaping, or the being burdened by a weight twice or thrice 
that of the whole body, causes no uneasiness to a sound foot; the injury, if 
any, resulting from such exertions being usually felt elsew'here. The skin, 
very thin and delicate on the upper part of the foot, is thick and tough, 
though soft and pliable, on the sole. Beneath it is a layer of fat, strengthened 
by strong fibers crossing it and binding it to the muscles and ligaments. 
The sole can endure great pressure and even violent shocks, but is at the 
same time curiously sensitive, especially to the touch. It is very easily 
tickled. This property serves a very important purpose in walking, for the 
pressure on the ground stimulates the muscles of the foot to their required 
activity without any effort of the will, and, indeed, without one being con- 
scious of the operation. This spontaneous alertness of the muscles, on 
which the energy and grace of movement depend, can be secured only by 
their being kept uncramped, free, and well exercised. 
How much the shoemaker’s shoes, cramping the foot, jamming the toes 
upon each other, destroying the shape of the organ, and lifting the heel up 
so that the weight of the body is thrown upon the toes, prevent this needs no 
elaboration. The lesson of these observations is that the shoe should give 
plenty of room all around to the foot, that the sole should be thinnest and 
narrowest at the “ waist,” where elasticity is wanted, broad and thick at the 
tread, where protection is most required, and that no one should be ashamed 
of the size of his foot. “ A wrell-formed, large one is a far pleasanter sight 
than the smallest one distorted.” — The Popular Science Monthly. 
RELATIVE STRENGTH OF MEN AND WOMEN. 
A French experimenter has tested the strength of 50 robust men and 
50 healthy women, all of the middle class of society, and between 25 and 
45 years of age. He used an apparatus recording the greatest downward 
pressure with the palm of the hand. The strongest man w7as able to give, 
with the right hand, a pressure equivalent to 187 pounds, and the weakest 
one of 88 pounds. The short men were nearly as strong as the tall, the 
average difference being less than 7 pounds. The force exerted by the 
strongest woman was only 97 pounds, and that by the weakest was but 
35 pounds, while the average was 72 pounds. — Medical Journal. APPENDIX. 
277 
THE USE OF LIQUIDS AT MEALS. 
Dr. Tev. O. Stratievsky, of St. Petersburg, after elaborate trials, has found 
that fluids materially assist the assimilation of proteids, and announces the 
following conclusion, which it is to be hoped no future experiments will 
controvert: “ On the whole, the widely spread custom of taking fluids during 
or just before one’s meals, proves to be rational and fully justified on strict 
scientific grounds. To take fluids with the meals is almost as important an 
adjunct to digestion as is the mastication of solid food preparatory to swal- 
lowing it. It is obvious, however, that there is a limit to the amount of fluid 
one can swallow with impunity — not to speak of comfort — just as much 
with meals as at other times.” It would be dangerous to create a general 
impression that the fluid is good with food irrespective of quantity. It is, 
moreover, a well-ascertained clinical fact that an excess of cumprandial fluid 
does not retard digestion in certain people, and gives rise to discomfort in 
most. A little attention to one’s sensations in such matters will far better 
fix the desirable limit than all the “ data ” in the world. — Medical Journal. 
SCIENCE AND ECONOMY IN COOKING. 
If the true way were comprehended, the right way made use of, the 
tougher but equally nutritious pieces of meat would be placed in suitable 
crockery dishes, these dishes or vessels would be placed in a suitable oven, a 
small oil lamp lighted at night, and in the morning a nutritious meat stew, 
soup stock, oatmeal, or salt fish cooked in milk, would be found ready 
either to be eaten at breakfast with the bread baked over the evening 
lamp all night; or it would be ready to be warmed over for the noonday 
meal. If a hot dish were desired without the expenditure of any of the noon- 
tide hour for the preparation of the meal, then the tougher portions of the 
meat would be put into the pan immediately after breakfast, treated with 
suitable relishes and flavorings, many vegetables placed in other vessels, the 
lamp lighted and left burning five hours, when the dinner would be found 
ready to be served ; tender, nutritious, and appetizing, without any attention 
having been required in the interval. 
Both the real waste of food and the true waste of time are to be found in 
the attempt to cook quickly, which almost invariably results in cooking 
badly. Both the true saving of time and the true saving of food are to be 
found in learning the right way of preparing the material, then putting it 
under the right conditions, and there leaving it where the regulated measure 
of right heat may work upon it a certain number of hours. 
This is the art which can be learned from those who have mastered the 
science of cooking. It can be learned in a single week, perhaps in a day, by 
those who can read intelligently and comprehend what is printed, with a little 
practice. — Edward Atkinson. 
COFFEE: A PHYSICIANS VIEW 
I venture the opinion that there is no beverage on earth to-day which,' 
used in moderation, expresses more comfort, contentment, and calmness to 
the cerebral centers than coffee. But in excess it is undoubtedly most 
dangerous. . . . The infusion of coffee in proper quantities aids diges- 278 
APPENDIX, 
tion, and is a safe cerebro-spinal stimulant, which is not followed by percepti- 
ble reactions. Leibig drew attention first to the fact that this beverage con- 
tains the elements which stimulate the flow of bile. It is a decided laxative ; 
a pronounced diuretic. The fact that the coffee belt of the world is also the 
“ bilious belt ” and the malarial belt, as well as the field where noxious 
germs and suppurative processes most abound, is evidence of the fitness of 
things. No one knows better than the citizens of the hot regions of the 
world the value of coffee to open up the secretions which have been checked 
by excessive heat or the malarial influence. They know well, and have 
known for centuries, that which has recently been receiving much attention 
by the medical world, particularly in Germany, viz. the antiseptic qualities of 
coffee. — 1. N. Love, M.D., St. Louis. 
HEREDITARY EFFECTS OF ALCOHOL. 
Demme studied 10 families of drinkers and 10 families of temperate 
persons. The direct posterity of the 10 families of drinkers included 57 
children. Of these 25 died in the first weeks and months of their life, 6 
were idiots, in 5 children a striking backwardness of their longitudinal 
growth was observed, 5 were affected with epilepsy, 5 with inborn diseases. 
One boy was taken with chorea and became idiotic. Thus of the 57 children 
of drinkers only 10, or 17.5 per cent, showed a normal constitution and de- 
velopment. The 10 sober families had 61 children, 5 only dying in the first 
weeks; 4 were affected with curable diseases of the nervous system ; 2 only 
presented inborn defects. The remaining 50 — 81.9 per cent — were nor- 
mal in their constitution and development. From this series of investiga- 
tions we derive the sad truth that among the children of drinkers the pre- 
vailing mortality is fearful, that the survivors represent a pitiful crowd, 
afflicted with unsoundness of mind, idiocy, epilepsy, and other disturbances 
of their nervous system, and that only a very small proportion of the 
descendants grow up as useful members of society. — Herald of Health. 
BLOOD CORPUSCLES. 
The blood globules of all warm-blooded quadrupeds, with the exception of 
the camel family, resemble those of the human species in shape and structure. 
They differ somewhat in size, being generally smaller than in man. There 
are but two species in which they are known to be larger than in man ; viz. 
the Indian elephant, in which they are of an inch, and the two-toothed 
sloth (Bradypus didactylus), in which they are 2^T of an inch in diameter. 
In the musk deer of Java they are smaller than in any known species, 
measuring less than xx of an inch. According to the best authority, the 
comparative .size of the red globules of blood in the principal mammalian 
species may be shown in the following list: — 
Ape . . . XX(T(T °f an inch. 
Horse . . “ 
Ox . . . “ 
Sheep . . Ty-sVff “ 
Goat. . . 44 
Dog • • • tsW 44 
Celt . . . inch. 
FOX. . . “ 
Wolf . . rJtns 14 
Elephant . 4 4 
Red Deer . “ 
Musk Deer “ APPENDIX. 
279 
According to the estimate of Vierodt, five millions of red globules are 
present in every cubic millimeter of healthy human blood. As the red 
globules or corpuscles are circular, biconcave disks in all mammals, except 
the camel tribe, so in all birds, reptiles, and amphibia they are either oval 
or elliptical. — Popular Science News. 
BLOOD-PLAQUES. 
There is a “third corpuscle”. in the blood, known variously as “ hemato- 
blasts ” and by other names, but best by the name given them by Bizzozero, 
“ blood-plates,” or “ blood-plaques.” They are colorless, protoplasmic disks, 
constant in mammalian blood, measuring 1.5 to 3.5 micromillimeters, and 
about the ratio of one to eighteen or twenty red ones, as a rule. They are 
colorless, homogeneous, or finely granular, probably without a nucleus. 
They are increased in number in a large number of diseases, and bear an 
important relation to the coagulation of the blood, and especially to the 
formation of thrombi.— Gray's “Anatomy.” 
CARBON DIOXIDE IN THE AIR. 
The amount of carbon dioxide in the expired air may be taken as a gauge 
or index of its impurity, even though this gas in itself be not injurious, for the 
more carbon dioxide present, the more poisonous organic exhalations from 
the lungs. Waller’s “Introduction to Human Physiology” says that when 
the carbon dioxide does not exceed 2 parts in 10,000 the air may be con- 
sidered “ fresh ”; when between 2 and 4 parts in 10,000, it begins to feel 
“ close ”; between 4 and 6 parts per 10,000, it is “ decidedly close ”; and 
between 8 and 10 parts per 10,000, the air is “foul”; and beyond this limit 
intolerable for any length of time. 
THE FINGER NAILS. 
There is a common belief that the finger nails are poisonous, which idea 
is natural enough, considering the fact that scratches made by them are 
generally quite irritable and much inclined to unusual inflammation. The 
reasoning is erroneous, however, for, as far as is known, the nails themselves 
do not have any poisonous properties. The trouble excited by them is due 
to the foreign deposits under them. In other words, if one keeps his nails 
clean, scratches caused by them will be no more irritable than those produced 
by any like instrument that is considered innocent. The results of the 
examinations made in Vienna show that it is more important that the fin- 
ger nails be kept clean than is supposed. Seventy-eight were made, and 
there were found thirty kinds of micrococci, eighteen different bacilli, and 
three kinds of sarcinse; besides common mould spores were present in many 
instances. It would seem from this that the spaces under the finger nails 
were favorable hiding-places for minute organisms which are more or less 
prejudicial to health, and that therein lies the poisonous element attributed 
to nails; furthermore, that cleanliness of the nails is a very important 
essential. It is not sufficient to use merely a knife blade, but at the toilet a 
nail brush and plenty of soap and water should be called into service. 280 
APPENDIX. 
Surgeons long ago learned that deposits under the nails were a menace, 
and that through them wounds were easily poisoned. This led to extreme 
care in the matter of personal cleanliness on their own part and on the part 
of all their assistants. Before an operation is performed all who touch the 
patient or the instruments must first clean their hands thoroughly with 
soap and water, being especially careful to have the spaces under the nails 
absolutely clean ; then the hands are put into disinfectant solutions. — Hall’s 
“Journal of Health.” 
THE SUDORIPAROUS GLANDS. 
Their number varies. They are most numerous on the palm of the hand, 
presenting, according to Krause, 2800 orifices on a square inch of the 
integument, and are rather less numerous on the sole of the foot. In both 
these situations the orifices of the ducts are exceedingly regular, and corre- 
spond to the small, transverse grooves which intersect the ridges of papilke. 
In other situations they are more irregularly scattered, but in nearly equal 
numbers, over parts including the same extent of surface. In the neck and 
back they are least numerous, their number amounting to 417 on the 
square inch (Krause). Their total number is estimated by the same writer 
at 2,381,248, and supposing the aperture of each gland to represent a 
surface of of a line in diameter, he calculates that the whole of these 
glands would present an evaporating surface of about eight square inches. 
Each gland consists of a single tube, intricately convoluted, terminating at 
one end by a blind extremity, and opening at the other end upon the surface 
of the skin.— Gray's “ Anatomy." 
DISTRIBUTION OP FUNCTIONS IN THE CEREBRUM. 
Until recently but little was known of the special functions of special 
parts of the gray matter of the surface of the brain. Of late years many 
experiments have been made upon dogs and monkeys, and a great deal of 
information has been obtained from observations of the actions of human 
beings with disease in different portions of the brain, so that at present a 
tolerably accurate knowledge of the localization of functions of the brain has 
been obtained. 
The following quotations from an article by Ambrose L. Ranney, M.D., 
sum up our present knowledge of the functions of the cerebral cortex, or the 
shell of gray matter on the surface of the brain : — 
In summary we are justified in drawing the following conclusions respect- 
ing the cells of the cerebral cortex from the results obtained by experimenta- 
tion, clinical experience, and pathological data. 
1. The surface of the brain is the seat of all conscious mental action. It 
is the receptacle of all impressions made upon the organs of smell, sight, taste, 
hearing, and the tactile organs of the skin. Here, and only here, do such 
impressions become transformed into a conscious appreciation of external 
objects. 
2. The mental powers are the result of different combinations of memories 
of past events and the activity of groups of cells that are probably situated 
in the frontal lobes. Although the integrity of the entire organ is necessary 
to the unimpeded action of the higher mental faculties (such as judgment, APPENDIX. 
281 
will, self-control, reason, etc.), the cells of that portion of the frontal lobes 
that lies in front of the motor centers are perhaps more closely associated 
with these faculties than those of any other area. 
3. The central convolutions of the brain (a part of the frontal and 
parietal lobes of each hemisphere) preside exclusively over motion. The 
upper part governs the legs chiefly, the middle part controls the upper 
extremity, while the lower part presides over the complex movements of the 
tongue and lips necessary to speech. The memories of muscular acts are 
probably stored within the cells of the motor area. 
4. The occipital lobes preside over the sense of sight and the memory 
of sight pictures. The recognition of familiar objects by the eye depends 
on the activity of the cells of the cortex of these lobes. Hallucinations of 
vision point strongly toward a disturbance of the function of these cells. 
An inability to recognize familiar objects, such as faces, letters, words, etc., 
is one of the prominent symptoms of disease of the occipital region, provided 
the eyes are capable of performing their normal functions. Colored percep- 
tions of objects and other ocular spectra often accompany irritation of these 
lobes. If the whole of the occipital lobes be not destroyed, the unimpaired 
part may slowly accumulate new sight memories, and the sense of vision may 
thus be slowly regained. This has been proven upon the dog by Professor 
Munk. 
5. That part of the parietal lobes which is not occupied by special 
centers of motion is probably associated with the conscious perceptions of 
various tactile impressions, and the associated memories of touch, tempera- 
ture, degrees of pressure, and pain. 
6. The temporal lobes are the seat of our conscious appreciation of 
sounds, odors, and taste. When these lobes are diseased, the memory of 
spoken words may be obliter- 
ated, and hallucinations of 
hearing, or deafness, may be 
developed. I once encoun- 
tered an interesting case 
where hallucinations of smell 
(imaginary odors) existed in 
consequence of disease in- 
volving the apex of this lobe. 
Cases of persons who were 
suddenly deprived of their 
ability to appreciate a ques- 
tion when spoken, but who 
would reply promptly to the 
same question if written be- 
fore their eyes, have been 
reported. In such the mem- 
ories of sound have been 
obliterated by disease of the 
temporal lobe, but the mem- 
ories of the form and mean- 
ing of letters have remained 
intact, because the occipital 
lobes were not involved. These patients can often be made to repeat 
mechanically word upon word, in a parrot-like way, but the memory of their 
meaning has gone forever. 
7. The power of speech (when regarded as a mere mechanical perform- 
Fig. 32. — Dr. Ranney’s Diagram showing Func- 
tions of Different Areas of the Cerebral 
Cortex. 282 
APPENDIX. 
ance) seems to be governed by the inferior frontal convolution and the area 
adjacent to it around the lower part of the fissure of Sylvius. But it must be 
remembered that our remarks are usually called forth by some form of 
excitation, such as a spoken question, an impression upon the eye, or some 
form of irritation of the sensory nerves, as in the case of pain, tickling, etc., 
for example. Disease of this limited area of the brain’s surface causes 
patients to frequently interpolate wrong words in conversation, in spite of 
the fact that they grasp the meaning of all that transpires about them and 
have the memories of past events perfectly at their command. Such a 
subject could write a reply to any spoken or written question with perfect 
accuracy, although he might speak it incorrectly. If he were asked to repeat 
words selected as a test of co-ordinate movements of the tongue and lips he 
would probably fail to do so with his accustomed facility. 
8. That we are endowed with memories of muscular movements is well 
illustrated by a case observed by Professor Charcot of a gentleman who was 
rendered incapable, by disease of the brain, of recognizing either printed or 
written language, but who could grasp the meaning of both with ease by 
tracing out the curves with his fingers. The habit of writing had impressed 
the mind with the symbols of thought through the agency of the muscles. 
9. Some collections of cells within the deeper parts of the brain (the 
corpus striatum and optic thalamus of each cerebral hemisphere) are 
probably distributing centers for all impulses that pass either to or from 
the cerebral cortex. They act as middlemen as it were. They are capable 
of an automatic control over movements ; but, as far as we know, there is no 
reason to think that they are associated in any way with the attribute of 
consciousness. 
10. The functions of the cerebellum, the pons Varolii, and the medulla 
oblongata are too complex to be discussed here. Their cells are called into 
action in a reflex manner rather than by volition. There is reason to believe 
that the cerebellum is an “ informing depot ” for the cerebrum, and a “ store- 
house for nerve force.” The medulla presides over acts that are chiefly 
outside of the domain of the will, such as the beating of the heart, the worin- 
like movement of the intestine, the regulation of the caliber of the blood- 
vessels to the wants of the different organs, the modifications of blood 
pressure, and other functions that are essentially vital. 
BRAIN WORK AND INSANITY. 
Does excessive brain work tend to produce insanity ? The best authorities 
are generally agreed that mental labor of itself does not have this tendency. 
It is gratifying, however, to have statistical evidence bearing upon the 
question, and we see that Dr. O. Evart, in the “American Practitioner,” 
gives the results of his large experience. From 1870 to 1876 he admitted 
into the general insane asylum in Ohio 1201 patients. Of these but 17 had 
received an academic education. Only 25 professed to be professional men. 
As we have more than once said in the “ News,” a man in good health seems 
to be able to do an almost unlimited amount of mental work, provided it 
is not attended with anxiety. It is worry, not work, that generally breaks 
him down. — Popular Science News. 
RELATIONS OF MIND AND BODY. 
It must be distinctly understood that our mental condition is most exten- 
sively influenced by corporeal states. Certain conditions of the nervous APPENDIX. 
283 
centers modify their workings and mould their products, thought amongst the 
rest. When the nutrition of the brain, and especially those tiny, microscopic 
cells upon whose activity thought, or at any rate the manifestations of 
thought, depends, is modified or interfered with by any physical condition, a 
distinct effect is produced, viz. a condition of mental pain, otherwise 
unhappiness and depression, is induced. The brain feels as pain intensified 
sensations from other parts, but it is insensitive to pain itself. The con- 
dition which produces neuralgia in the peripheral nerves is mental pain in 
the cells of the brain itself. When they are well fed and unexhausted, they 
endow the individual with a sense of well-being, of comfort, and of energy; 
when ill-fed and exhausted, this condition expresses itself in a feeling of dis- 
comfort, of wretchedness, and apprehension. The thoughts are steeped in 
misery during such periods, and the affairs of life assume a different hue and 
complexion according as these physical conditions vary. When the brain is 
well supplied by a powerful circulation, and a rich blood supply from a 
good digestion furnishes it with an abundance of pabulum, the cares of life 
are borne with cheerfulness and sustained with equanimity. But when the 
physical condition becomes affected a total and complete change may be, and 
commonly is, induced. The change is as great as is that betwixt a bright, 
sunny May morning with a cheering breeze and the sultry, oppressive 
electrical condition which ushers in the violence of a black, darkening 
thunderstorm. Things look very differently in the light of a bright morning 
to what they appear during the dark gloom of the impending thundercloud. 
But, after all, the things are the same, however much in appearance they may 
seem altered. — J. Milner Fothergill, M.D., M.R.C.P. 
THE RATE OF NERVE FORCE. 
In the “ Nineteenth Century ” Dr. J. McK. Cattell gives an account of the 
time-measurements of thought made by means of the line drawn on a 
rapidly moving surface by a pen attached to the prong of a tuning fork 
vibrating at a constant rate, by means of electricity. By a delicate appa- 
ratus constructed on this principle, duration of time may be measured to 
the jTnhre of a second. The writer above named has found that the 
process of thought varies in its degree of rapidity in different individuals, 
children and old persons thinking slower than people of middle age, 
ignorant persons thinking more slowly than educated persons. In this way 
he also found that he could measure the time it takes to perceive, that is, the 
time which passes from the moment when the impression reaches conscious- 
ness until the moment at which we know what it is. In his own case he 
found that it took -fa second to see white light, second to see a picture, 
| to see a letter, and \ to see a word. It takes longer to see a rare word than 
a common word, or a word in a foreign language than in our native tongue. 
It even takes longer to see some letters than others. “ Will time,” or time 
taken up in choosing can be measured. It takes W second to judge between 
blue and red. To recall the name of a printed word takes second, to a letter 
| second, to a picture \ second. It takes less time to remember the name of 
a familiar word than of a letter, though it takes less time to see the letter. 
The time of remembering can be measured. It takes \ second to translate 
a word from one language to another when one is familiar with both. It 
takes xV second longer to translate a word from a foreign language to one’s 
native tongue than it does in the other direction. We can think of the name 
of the next month in half the time we can think of the last month. It has 284 
APPENDIX. 
been demonstrated that sensation does not travel through the nerves to the 
brain so fast as has been supposed. Its speed is not much greater than sixty 
miles an hour.— Scientific Journal. 
The following, from “ General Physiology of Muscles and Nerves, by 
Rosenthal,” bears on the same point: — 
Let us suppose that an observer sitting in complete darkness suddenly sees 
a spark, and thereupon gives a signal. By a suitable apparatus both the time 
at which the spark really appeared and that at which the signal was given 
are recorded. The difference between the two can be measured, and it is 
called the physiological time for the sense of sight; the physiological time for 
the sense of hearing and for that of touch may be determined in the same 
way. Thus Professor Hirsch, of Neufchatel, found — 
In the case of the sense of sight 0.1974to 0.2083 sec. 
“ “ “ “ hearing 0.194 “ 
“ “ “ “ touch 0.1733 “ 
When the impression which was to be recorded was not unexpected, but 
was known beforehand, the physiological time proved to be much shorter; 
in the case of the sense of sight it was only from 0.07 to 0.11 of a second. 
From this it follows that, in the case of excitement, the advent of which is 
expected, the brain fulfills its work much more quickly. 
Certain experiments made by Bonders are yet more interesting. A person 
was instructed to make a signal, sometimes with the right hand, sometimes 
with the left, according as a gentle irritant applied to the skin was felt in 
one place or the other. If the place was known the signal succeeded the 
irritant after an interval of 0.205 of a second, but if the place was not knowm 
only after an interval of 0.272 of a second. The psychological act of reflec- 
tion as to where the irritant occurred, and that of the corresponding choice 
of the hand, occupied, therefore, a period of 0.067 of a second. 
The physiological time in the case of the sense of sight was somewhat 
dependent on color; white light was always noticed somewhat sooner than 
l’ed. If the observer knew the color which he was to see he gave the signal 
sooner than when this was not the case, arid he had first to reflect as to what 
he had seen before he gave the signal. In such experiments the observer 
always forms a preconception of the color which he expects to see. If the 
color when it becomes observable corresponds with that which he expected, 
the reaction in the observer takes place sooner than wThen this is not the case. 
Similar observations were made in the case of the sense of hearing. The 
recognition of any sound heard follows sooner when it is known beforehand 
what sound is to be heard than when this is not the case. 
Dr. Alexander Bain says : “ The example is put by M. Du Bois Raymond 
of a whale, 90 feet long, struck in the tail by a harpoon; one second would 
be occupied in transmitting the impression to the brain, a fraction of a 
second, say in traversing the brain, a full second in returning the 
motor impulse, so that the boat would have upward of two seconds for 
escaping the danger.” Some one has estimated that if a child had an arm 
long enough to reach to the sun it would die of old age long before it would 
know that its fingers were burned. 
THE NUMBER OF NERVE CELLS AND FIBERS IN THE 
BRAIN. 
The thin cake of gray substance surrounding the hemispheres of the brain, 
and extending into its many doublings by the furrowed or convoluted APPENDIX. 
285 
structure, is somewhat difficult to measure. It has been estimated at upwards 
of 300 square inches, or as nearly equal to a square surface of 18 inches in 
the side. Its thickness is variable, but, on an average, it may be stated at 
of an inch. It is the largest accumulation of gray matter in the body. 
It is made up of several layers of gray substance, divided by layers of white 
substance. The gray substance is a very nearly compact mass of corpuscles 
of variable size. The large caudate nerve cells are mingled with very small 
corpuscles, less than the thousandth of an inch in diameter. Allowing for 
intervals, we may suppose that a linear row of 500 cells occupies an inch, 
thus giving a quarter of a million to the square inch for 300 inches. If one 
half of the thickness of the layer is made up of fibers, the corpuscles, or 
cells, taken by themselves would be a mass of an inch thick, say 
16 cells in depth. Multiplying these numbers together we should reach 
a total of 1,200,000,000 of cells in the gray covering of the hemispheres. As 
every cell is united with at least two fibers, often many more, we may 
multiply this number by 4 for the number of connecting fibers attached to 
the mass, which gives 4,800,000,000 of fibers. —Alexander Bain, LL.D. 
THE COLOR SENSE. 
We may suppose that all over the surface of the retina nervous termina- 
tions are closely packed, belonging to three orders which correspond to three 
classes of fibers and their connected central organs. Each order of termina- 
tions vibrates in sympathy with a system of ether waves possessing a limited 
though widely varying rate of oscillation only. From the stimulation of 
those in sympathy with the slowest (visible) waves arises the sensation of red. 
From the stimulation of those in sympathy with waves having a medium rate 
of oscillation arises the sensation of green. From the stimulation of those 
in sympathy with the quickest (visible) waves arises the sensation of violet. 
All other sensations of color are due to combinations of these in different 
degrees of intensity. Stimulation of all three simultaneously produces the 
feeling [sensation] of whiteness. Stimulation of the red and green produces 
the sensation called yellow; of the green and violet, that called blue; of the 
violet and red, that called purple. Hence, the visible shape of any object 
depends upon the number and position of the points in the retina affected by 
it; its color depends upon the class of nervous terminations stimulated; and 
this last point again depends upon the rapidity of the ether waves which in- 
fringe upon that particular portion. So that, in the eye as in the ear, differ- 
ences of sensation are ultimately explicable as due to differences in the 
several structures involved.— Grant Allen, “ Physiological Aesthetics.” 
THE ARBORESCENT FIGURE OF PURKINJE. 
One of the most interesting entoptic phenomena is the Arborescent Figure, 
discovered by Purkinje. If, towards evening, we place ourselves opposite a 
dark wall in a dark room and move a lighted candle to and fro before our 
eyes, looking, however, fixedly at the wall beyond, we shall then, after a little 
practice, see this arborescent figure, whose intersecting branches cover the 
whole of the dark space, and which is unmistakably caused by the blood- 
vessels in the interior of the eye. The field of vision assumes a reddish 
appearance, upon which the veins stand out in dark shadows. The trunk of 
the figure rises a little on one side of the center, where the optic nerve 
enters the eye, and thence branches out after the manner of blood-vessels, 286 
APPENDIX. 
which is undoubtedly a proof that in this experiment we see the blood-vessels 
of the retina itself. One spot alone is free from vessels: the yellow spot, 
which is the most sensitive to light of all parts of the retina. If now the 
candle is moved to and fro, the figure will also move and follow the direction 
of the light. That these vessels cast a shadow behind them is clear, but that 
the shadow should be sufficient to cause a perception leads to the very 
important and interesting fact that the elements of the retina which receive 
the impression of light must lie behind the blood-vessels. — “ The Five Senses 
of Man,” Bernstein. 
HEARING WITHOUT AIR. 
There is a well-known children’s game, which depends chiefly upon the con- 
veyance of sound to the ear through bone. A metallic spoon is fastened to 
a string which is wound round the first finger, and the finger pressed firmly 
into the auditory canal. The spoon is then struck against the edge of 
the table, and the sound produced resembles that of a large bell, for the 
vibrations of the spoon are communicated to the labyrinth through the 
thread, the finger, and the bones of the skull with increased intensity. 
The communication of sound through bone is of no value to man under 
ordinary circumstances, since we do not generally bring the head into close 
contact with the sounding body. In fishes, however, it plays a very im- 
portant part, for they possess neither external ear, auditory canal, nor ear- 
bones, but only a labyrinth, which is entirely closed by walls of bone, or is 
only covered with membrane on its outer surface. The sound-waves of the 
water, therefore, are transferred directly to the fluid of the labyrinth through 
the bone. This is possible because the sound-waves of water, which is well 
known to be incompressible, are similar to those of a solid body, and do not, 
like those of the air, consist of expansions and condensations. Sound-waves 
of the air, on the contrary, are transferred to solid bodies and to liquids with 
great difficulty; and to effect this ingenious contrivances are required, which 
are found in their greatest perfection in our ears. Such contrivances are not 
required by fishes, for they have only to hear in water; indeed, an apparatus 
filled with air, if placed between the water and the labyrinth of their ear, 
would considerably diminish their power of hearing. In cases of illness the 
communication of sound through the bones can be of considerable importance 
to us. If the apparatus for the communication of sound is diseased, and can 
no longer perform its duties, in spite of deafness sound can still be com- 
municated by means of bone, which then gives the physician a very 
important diagnostic sign that the labyrinth and the auditory nerve are in a 
sound condition. — Bernstein. 
THE GERM THEORY. 
The contagious or infectious principle, unlike all other causes of disease, 
accumulates after it enters the system. We can account for this accumula- 
tion in no other way than that it is a living, growing germ, capable of 
reproducing itself. A drop of matter taken from the pustule of a small-pox 
patient and introduced into the body of another produces small-pox. Here, 
again, are multiplied hundreds of pustules, each of which contains many 
drops of matter identical with that first introduced. That it has not lost any 
of its virulence or potency is evidenced by the fact that it will produce the 
disease in a third person as surely and quickly as the original drop did in the APPENDIX. 
287 
second. From the first drop there has been a prodigious increase in 
quantity; and thus it has been throughout the ages. No other cause, 
whether it be animal, mineral, or vegetable in its nature, if not endowed with 
life and the power of procreation, will pei’petuate a disease of unabated 
intensity through successive individuals. Strychnine given to an animal will 
produce its characteristic effects, but these effects cannot be maintained by 
transmission from one animal to another. So it is with the mineral poisons 
and the non-contagious animal poisons. The experiment has often been 
made of submitting a fowl to be bitten by a venomous reptile and establish- 
ing therefrom a series of inoculations. The fowl bitten speedily succumbs 
to the virulence of the poison introduced into its system. A second one, 
inoculated from the blood of this, may die, but less speedily. A third, 
inoculated from the second, is much less profoundly affected, and so on con- 
tinually, the poison losing its strength as it becomes diluted by dissemination 
through different bodies, until it finally becomes practically inert. So it is 
with all other known substances, except such as consist of living elements. 
Every contagious disease has its own special contagium, which differs from 
that of all others, and which imparts to the disease its distinguishing char- 
acters. Thus, the contagium of small-pox differs from that of scarlet fever, 
cholera, or any other contagious disease, and always produces small-pox. So 
it is with other contagia ; each produces its kind and nothing else. 
The ordinary parasites of the body are the grosser representatives of the 
minute organisms which we call contagia. Fleas, lice, and ticks infest the 
surface of the body; they grow and multiply, pass from individual to 
individual, and produce their characteristic effects on each. They are con- 
tagious. The same may be said of the intestinal worms, and by the aid of 
the microscope numerous other parasites are revealed. These are too small 
to be detected by the naked eye, yet none the less certainly the producers of 
disease. 
As familiar examples, we may mention the itch mite, the trichina spiralis, 
and the filaria medinensis, each of which gives rise to its characteristic 
disease. Lowly organisms have been found in most of the contagious and 
infectious diseases ; notably in cholera, typhoid fever, diphtheria, small-pox, 
erysipelas, relapsing fever, and the septic diseases. It can hardly be claimed 
that for the present the specific contagium for either of the above has been 
affixed beyond question, though the field is being cleared for subsequent 
investigations. — IJ. Tod Gilliam, M.D. 
Much evidence has accumulated to show that the average duration of 
human life has been increasing for some years past. Formerly it was set 
down as 33 years; it is now 35 years. The gain in longevity is greatest 
among educated men familiar with the laws of hygiene. Among Yale 
College graduates the records show that, from 1701 to 1745, 32 out of every 
100 lived beyond 70; between 1875 and .1885,40 out of every 100 lived 
beyond 70. Similar records in England show like results. 
We frequently see newspaper accounts of men and women who have lived 
to the age of 110 and even 120 years. These accounts are set down by 
physiologists and medical men as pure fictions. Mr. Thoms, who has 
written a work on longevity, says : “Any evidence that can be produced of 
any human being having attained the age, not of 130 or 140, but of 110 will 
be found on examination to be perfectly worthless.” Dr. Gardner says: 
LONGEVITY. 288 
APPENDIX, 
“ The historical evidence up to the present time fails in proof of any person’s 
having reached even 105 years.” 
“ The longevity of stagnant villages and country parsons proves how 
infinitely health outweighs all other means of happiness. The peasants of 
Southern Russia live almost as frugally as the Hebrew patriarchs, on milk, 
bread and honey, with a bit of cheese now and then, or a drop of hydromel 
(half-fermented honey-water) ; their climate is dry and favorable to outdoor 
life, and, in spite of official tyranny, war and rumors of war, feudalism, and 
outrageous over-taxation, they outlive the free-born British yeoman, with his 
strong ales and daily beefsteaks. But the coincidence of dietetic and 
administrative abuses cuts the thread of life with a two-edged knife, and in 
Northern Russia the average duration of life is 10 years less than among the 
equally intemperate but less misgoverned natives of Northern Germany, and 
almost 20 years less than in the equally despotic but less poison-cursed 
territories of the Shah.” — Felix L. Oswald, M.D. 
THE HUMAN FORM. 
The Greek sculptors, it is said, used the following rules in making their 
statues: — 
1. From the crown of the head to the nape of the neck is one-twelfth of the 
height. 
2. The face from the point on the forehead where the hair begins to the 
tip of the chin is one-tenth of the height. 
3. The length of the right foot is one-sixth of the height. 
4. The distance between the finger tips of each hand when the arms are 
extended in opposite directions is exactly equal to the height. 
5. The distance from the wrist to the tip of the middle finger is one-tenth 
of the height. 
6. From the place where the hair begins on the forehead to the place of 
meeting of the eyebrows, from this point to the nostrils, and from the latter 
to the tip of the chin are equal distances. 
SEAT OF THE GREATEST GROWTH. 
The entire body from birth to adult life increases 3.37 times. The entire 
leg increases 4.49 times, but the lower end of the femur increases 7.30 times, 
so we may say that we grow in height mainly by lengthening of the lower 
end of the femur. 
DIFFERENCES IN THE MALE AND FEMALE SKELETON. 
All the parts of the female skeleton are lighter and more frail; the general 
contour is more soft and graceful; the eminences, processes, or tubercles are 
smaller and less marked. If there is one well-established physiological fact 
it is this : that the- asperities which serve for the insertion of muscles are 
developed in proportion to the activity of those muscles. Less marked in the 
studious man than in the laborer, these asperities are still less so in the 
woman, especially in women residing in towns. This law is so exact that we 
can tell by the degree of prominence of the crests and processes what muscles 
the individual was most in the habit of using, and hence judge as to his pro- APPENDIX. 
289 
fession or calling. As a sequence of these prominences, the depressions, 
grooves, and marks are more distinct in the man. So the temporal ridge, which 
serves superiorly for the insertion of the temporal muscle, and the trans- 
verse ridges, which divide the internal surface of the scapula and serve for 
the insertion of the subscapularis muscle, are more marked in the male ; the 
groove of torsion of the humerus is more visible, and the two S-like curva- 
tures of the clavicle are stronger. 
In the woman, on the contrary, the external protuberance of the occipital 
and the two subjacent curved lines, wrhicli serve for the insertion of the 
muscles of the nucha; the anterior tubercle of the tibia, to which the triceps 
femoris is attached; the tuberosity of the radius, which gives insertion to the 
biceps of the humerus — are less prominent. The curved alveolar borders 
are more regular, the borders of the malar bone are less thick, the canine 
fossa is less deep. In a word, it is tolerably easy to determine the sex by 
the appearance of a bone : in the case of a long bone we are rarely in doubt; 
in a short bone, as the calcaneum, it is still more possible to do so. But we 
must not be surprised if we are occasionally at fault. . . . On the 
skeleton, a woman who had worked hard all her life would have the bony 
prominences and the processes for the attachment of muscles more developed 
probably than a man who had not worked at all. . . . The head of the woman 
is smaller and lighter, its contours more delicate, the surfaces smoother, 
the ridges and processes not so marked. The superciliary arches are but 
little prominent; the external half of the superior orbital border is thin and 
sharp. The forehead is vertical below, projecting above. The occipital 
condyles are small, as also the styloid and mastoid processes. . . . The 
inferior maxillary is smaller, its posterior angles having no projecting rough- 
nesses. The frontal sinus is less developed. — Dr. Paul Topinard. 
COMPRESSION OF THE INTERVERTEBRAL CARTILAGES. 
A person is taller in the morning than at night. The reason is that he is 
pressed down during the day by the weight of the atmosphere, and by the 
pressure of the upper parts of his body and such burdens as he may carry. 
These weights press down the cartilages at the joints, and especially those in 
the spinal column, so that the height of the man is reduced. When the weights 
are removed and he lies down at night the cartilages act like cushions and 
gradually return to their original size. M. Robert reports measurements of 
287 persons, showing a difference in height between morning and night 
measurements of 6 to 20 millimeters (I to f of an inch). This fact is well 
understood among French conscripts, and M. Paul Topinard reports that 
some of them, who are just upon or very slightly above the minimum 
limit as to height, walk about with heavy weights upon their shoulders for 
several days and during the night immediately preceding the final measure- 
ments, in order to reduce their heights. This practice has been so successful 
that in some extreme cases, according to the same authority, the height of a 
man has been reduced by it more than an inch. As men advance in age the 
cartilages do not fully recover during the night from the effects of the day’s 
compression. The result of this is that men are commonly not so tall at an 
advanced age as in middle life. Extreme cases of this, reported by M. 
Tenon, are of a man who had lost li inches at the age of 70, and another 
who had lost 1 inches at the age of 85. — Medical Journal. 290 
APPENDIX. 
ANATOMICAL LANDMARKS. 
By this term we mean points on the surface of the body, such as lines, 
ridges, prominences, furrows, etc., which are guides to the location of 
important parts that are deeper seated. 
1. Supra-orbital Arch and Notch. — Commence at the angle of the nose 
and forehead and pass your finger along the eyebrows, pressing firmly. You 
feel a sharp ridge of bone. This is the supra-orbital arch. In some persons 
a depression may be felt at the inner side of the middle of this arch. This 
is the supra-orbital notch, through which passes the supra-orbital artery, vein, 
and nerve. In othei’s, there is a foramen or hole through the bone instead 
of a notch, and it cannot be felt. The artery may generally be felt 
pulsating just above the arch. It is a branch of the ophthalmic, which is a 
branch of the internal carotid artery. The nerve is a branch of the fifth 
cranial nerve. 
2. The Mastoid Process. — This is the prominence behind the ear. The 
cavities in this process probably act as a sounding-board, and increase the 
resonant properties of the middle ear. The portion of bone between these 
cells and the brain is sometimes very thin, and inflammation of the mucous 
membrane lining them may spread to the brain and result seriously. 
3. The Occipital Protuberance. — The bump which may easily be felt 
on the back of the head is the occipital protuberance. The skull is very 
thick at this point, there being an elevation on the inner side of the bone 
also. It is more prominent in very muscular persons. It gives attachment 
to the ligamentum nuchas, a strong elastic ligament which unites the spinous 
processes of the seven cervical vertebra;. “In man it is merely the rudiment of 
an important elastic ligament which sustains the weight of the head.” — 
Gray's “Anatomy.” 
4. The Pulley for the Superior Oblique Muscle of the Eye may be 
felt by pressing the finger against the frontal bone in the inner and upper 
part of the orbit of the eye. 
5. The Thyroid and Cricoid Cartilages are easily felt. As your finger 
passes down from the point of the thyroid cartilage a slight depression is felt 
before you reach the cricoid. This is the crico-thyroid space. Here there is 
no cartilage, nothing but the skin and a membrane between the interior of 
the larynx and the exterior of the body. At this point an incision may be 
made by the surgeon and a tube inserted in cases of croup or other obstruc- 
tion of the air passages. The operation is not likely to be dangerous and 
has often saved lives. The ignorance of many people concerning the 
anatomy of the body often stands in the way of surgical operations that 
might be the means of saving life. Many persons regard any operation about 
the throat as exceedingly dangerous and will not trust the surgeon to make 
them. 
6. The Subclavian Artery. — By standing behind a person and press- 
ing with the thumb in the hollow above the clavicle, near the sternum, the 
pulsation of the subclavian artery may be felt. It can be compressed against 
the first rib by pushing downward and a little inward. In case of wounds 
about the shoulders and chest it might some time be of importance to know 
how to stop the flow of blood in this vessel by pressure of the thumb until 
surgical assistance could be brought. 
7. Parts behind the First Bone of the Sternum. — “ There is little or 
no lung behind the first bone of the sternum, the space being occupied by 
the trachea and large vessels, as follows : — APPENDIX 
291 
“ The left vena innominata crosses the sternum just below the upper border. 
Next come the great primary branches of the arch of the aorta. Deeper 
still is the trachea, dividing into its two bronchi opposite the junction of the 
first and second bones of the sternum. Deepest of all is the esophagus. 
About one inch from the upper border of the sternum is the highest part of the 
aorta, which lies on the bifurcation of the trachea.” — Gray’s “Anatomy.” 
8. The Heart. — “A needle passed through the second intercostal space 
to the right side of the sternum would pass through the lung, enter the 
pericardium and the most prominent part of the bulge of the aorta. A 
needle passed through the first intercostal space close to the right side of the 
sternum would pass through the lung and enter the superior vena cava above 
the pericardium. The aortic valves lie behind the third intercostal space, 
close to the left side of the sternum. The pulmonary valves lie in front of 
the aortic, behind the junction of the third intercostal cartilage on the left 
side of the sternum. The tricuspid valves lie behind the middle of the 
sternum, about the level of the fourth costal cartilage. The mitral valves 
(the deepest of all) lie behind the third intercostal space, about one inch to 
the left of the sternum.” — Gray’s “Anatomy.” 
9. Liver and Spleen. — There are three areas on the abdomen and chest 
where a tapping with the fingers will give a dull sound. All other places will 
give a hollow or drum-like sound. First, a small area over the heart; second, 
a larger area over the spleen; and third, a still larger over the liver. In this 
way one can locate tolerably well these organs. 
10. The Knee Joint. — The patella can easily be outlined with the fingers 
when the limb is extended. It can also be made to slide back and forth 
beneath the skin in this position of the limb, but when the leg is bent it is 
fixed by the stretching of the tendons attached above and below it. The 
enlarged heads (condyles) of the femur may be felt as prominences on either 
side of the knee joint; also the enlarged portions (tuberosities) of the tibia. 
The patella lies over the middle of the joint when the knee is bent, thus pro- 
tecting it when kneeling. When the leg is extended it is drawn above the joint. 
11. The “ Hamstrings.” — On either side of the hollow behind the knee 
(popliteal space) may be felt strong cords beneath the skin. They are 
popularly known as hamstrings, and are the tendons of the following- 
muscles : The outer hamstring is the tendon of the biceps of the leg. The 
inner hamstring is composed of the tendons of the semitendonosus, semi- 
membranosus, and gracilis. 
12. The Ankle Joint. — The prominent points on the outer and inner 
sides of the ankle are the external malleolus, or projection of the fibula, and 
the internal malleolus, or projection of the tibia. 
13. The Shoulder Joint. — The highest prominence of the shoulder is 
the acromion process of the scapula. The prominent ridge, or spine, of the 
scapula can always be distinctly felt. 
14. The Elbow Joint. — The tip of the elbow is the olecranon process of 
the ulna. The two other bony points which can be felt are the external and 
internal condyles of the humerus. In the depression between the olecranon 
process and the inner condyle lies the ulnar nerve. You may press the nerve 
with th6 thumb here sufficiently hard to produce a peculiar sensation in the 
third and little fingers. 
DISINFECTANTS AND THEIR USE. 
A disinfectant as generally understood is any substance which will destroy 
or remove bad odors or poisonous gases from the atmosphere. As we pro- 292 
APPENDIX 
pose to use the term it includes all means of destroying and removing 
injurious gases, liquids, and solids which may in any way injure animal life 
by contact either through breathing, through food, or by direct contact with 
the surface of the body. 
A convenient classification of disinfectants is here given, with a brief 
description of the more important ones. 
1. Antiseptics, or Decay-preventers. — Many substances are powerfully 
antiseptic, but at the same time are injurious of themselves and cannot be 
used in every case. Modern physicians regard corrosive sublimate (mercuric 
chloride) as the best antiseptic. It is a deadly poison if introduced into the 
system or applied to the surface in any ordinary quantity, but it has the 
peculiar power of destroying bacteria and other germs when used in an 
extremely diluted form. It can be used externally in solutions so weak that 
no injurious effect will be produced and yet destroy all germs of disease. 
We will not attempt to prescribe the form of its use here, but advise all to 
consult with a physician in regard to its proper use. Says Remington, “ It is 
undoubtedly the most powerful antiseptic available, the only serious disad- 
vantage being the necessity for great care on account of its poisonous 
properties.” 
Carbolic acid is also much used as an antiseptic. It should also be used 
with caution, as it is a powerful poison. Iodoform is a substance lately much 
employed as an antiseptic. It is also a poison when used too freely. 
Antiseptics, from their necessary poisonous character, cannot be used to 
destroy bacteria when the latter have gained access to the blood and tissues, 
but when properly used externally and upon instruments and appliances 
which come in contact with the body they are a means of preventing disease 
which should not be ignored. 
2. Deodorizers, or Smell-destroyers. — It must be held in mind that 
all disagreeable odors are not injurious to health, and that many very poison- 
ous gases have no disagreeable odor and that air may be laden with disease 
germs and have no perceptible indication of it in the way of odor or appear- 
ance ; yet, as a general rule, wherever there is a foul smell dangerous gases 
and bacteria-laden atmosphere exist also. 
One must distinguish also between smell-destroyers and mere smell-dis- 
guisers. Perfumes frequently so disguise the disagreeable odor by their more 
powerful agreeable smell that one does not recognize the bad odor; yet it 
still exists, and if dangerous at all is still dangerous. 
Water and other liquids, especially milk, are smell-removers to a great 
extent. They act by absorbing the gaseous substance, and thus take it 
from the atmosphere ; but if exposed to warm air these liquids evaporate and 
give off the odors again to the air. In the same manner many porous solid 
substances act, as dry earth, charcoal, chalk, etc. Dry earth can be used 
to great advantage, as it not only absorbs gases, but liquids, and holds them 
an indefinite time. Earth thus saturated with gases and liquids that are 
dangerous can be disinfected by adding chemicals which will neutralize and 
destroy the dangerous substances. 
There are, however, several substances which actually destroy bad-smelling 
gases by chemically combining with them. The most effectual of these is 
chlorine gas. The best way to use it is in the form of chloride of lime 
(bleaching powder). This, when exposed to the air, slowly gives off chlorine 
gas. It can be made to give it off rapidly by adding a little acid of any kind. 
Strong vinegar will answer. Chlorine gas is in itself dangerous when in any 
considerable quantities. It irritates the mucous membrane when inhaled, and 
if very strong will cause death. It also destroys most colors, and when strong APPENDIX, 
293 
will corrode clothing, paper, etc. It is best to remove clothing, books, and 
such like articles from a room which is to be disinfected. Johnston says of 
chlorine as a disinfectant: “ It is probably the most generally efficient for 
this purpose of any gaseous substance with which we are acquainted. And, 
besides its efficiency, it is further recommended by being easily and cheaply 
prepared; by producing its good effects even when so diluted with air as to 
be breathable without injurious effects. It can thus be used within a build- 
ing without displacing its inhabitants, and with little inconvenience even in 
the chambers of delicate invalids. In this diluted state, also, its use is free 
from almost every other objection. For, though it does corrode metallic 
substances, its evil effects in this way are much less sensible than those of 
any of the other gases already mentioned.” 
Quick-lime is a valuable and cheap disinfectant to be used upon solid or 
liquid substances and prevent the formation of injurious gases, but it has 
comparatively little effect on gases already in the atmosphere. 
Many an epidemic of disease may be cut short by a thorough and free use 
of disinfectants. It should be the duty of everyone to contribute something 
toward work of this kind. The student of physiology can use his advice, 
backed up by his knowledge of the human body and its liability to be affected 
by impure physical surroundings. 
COMPARATIVE ANATOMY. 
This is an extensive subject. We can only give here a few points of 
resemblance and difference in the structure of man and the lower animals. 
They are mainly condensed from Topinard’s “Anthropology.” 
All mammals have 7 cervical vertebrse, except the sloth, which has 9, and 
the sea-cow, which has 8. The long neck of the giraffe is due, not to increase 
in number of vertebrae, but to their individual length. The dorsal vertebrae 
vary much in number. The bat has 11, the elephant 20. The number of 
lumbar vertebrae varies little, generally from 4 to 7. The sea-cow, however, 
has but 1, and the dolphin 18. The ribs vary as the dorsal vertebrae. 
The divisions of the coccyx vary greatly, this bone corresponding to the 
bones of the tail in those mammals possessing one. The number of caudal 
vertebrae, or, in other words, divisions of the coccyx, varies from 2 in the 
tapir to 60 in the Cape rorqual. 
The bones of the head are in the main similar in the lower mammals to 
those of man. The principal differences being in the shape of the bones, and 
the consolidation of two or more into one in some cases, and their division 
by sutures in others. We see similar variations in man; for example, the 
frontal bone often remains in two pieces through life, and again the nasal 
bones frequently unite into one. 
If a line be drawn on a skull from the opening of the ear to the base of the 
nose, and another from the most prominent part of the forehead to the most 
projecting point of the upper jaw, the space between the lines forms an angle 
which is found to vary considerably in man, and to be much greater than in 
the highest mammals. There is also apparently a regular gradation from the 
most intelligent man down through the lower races, and from them through 
the lower animals, until we reach the fishes, wThich are the lowest of the back- 
boned animals. The angle in fishes and snakes is very small, in birds a little 
greater, in the lower mammals still greater, until we reach one species of ape 
which has an angle of 42 degrees, and another an angle of 50 degrees. Then 294 
APPENDIX. 
comes the African with an angle of 70 degrees, while in the European it is 
80 degrees or more. The painters and sculptors among the Greeks and 
Romans represented their highest ideal men and women with* faces having 
an angle of 90 degrees, while their gods they represented with angles of 
100 degi-ees. 
The angle made by lines forming axes of the orbits of the eyes varies also 
greatly in man and lower animals. It varies from 40 to 50 degrees in 
different men, from 30 to 62 in the monkeys, is 73 in the lemur, and 143 in 
the rabbit. 
The higher apes have the same number of teeth as man, but some monkeys 
have as many as 38. The number and shape vary greatly in other lower 
animals. Man is the only creature that can be said properly to have a chin, 
that is, a projection of the jaw in front of the insertion of the teeth. The 
foramen magnum in man is in the center of the base of the skull, and the 
head is poised upon the trunk, a condition not found in any of the lower 
animals. 
The innominata bones in man are broader in proportion to their length in 
consequence of the upright posture. They come into use to support the 
abdominal organs. 
The thorax is more developed transversely in man, and more so from before 
backward in quadrupeds. 
The clavicles are wanting in many animals as the cow, horse, etc. The 
sternum is broader in man than in quadrupeds. 
Man is the only animal that can the thumb to the fingers 
separately, as in picking up small objects. 
The pupil of the eye in man is perfectly circular. In many mammals 
which are preyed upon by others it is elongated horizontally. In many which 
seek their prey it is elongated vertically. 
All other mammals have a more perfect development of the muscles of the 
jaw, since the jaws alone are used in dividing the food. 
POISONS AND ANTIDOTES. 
When convinced that a poison has been swallowed, send for a doctor at 
once. But in the meantime something may be done which may save the 
patient’s life. If the nature of the poison be known, of course the thing to do 
is to administer the proper antidote if there be one. But you may not know 
what the antidote is, or if you do it may not be at hand. In these cases, and 
also where it is impossible to know what has been swallowed, the proper 
thing to do is to administer an emetic, that is, something that will incite 
immediate vomiting. A quick and harmless emetic is a teaspoonful of 
ground mustard in half a pint of lukewarm water. Salt and warm water, 
soapsuds, or simply large quantities of lukewarm water will also act as an 
emetic. In case none of these articles be obtainable, vomiting may often be 
induced by pushing the finger down the throat. 
Some poisons have no special antidote. In such cases any oily or muci- 
laginous substance should be given, such as oil or grease of any kind, cream, 
milk, white of egg, flour and water, or starch and water. These substances 
prevent rapid absorption of the poison by spreading over the mucous coat of 
the stomach. There is only one kind of poisoning in which oil or grease 
should not be used, and that is by phosphorus. 
Antidotes may be chemical or physiological. A chemical antidote acts by 
forming with the poison a harmless compound; in other words, it neutralizes 
the poison. A physiological antidote acts by producing an opposite physio- APPENDIX. 
295 
logical effect on the body, thus neutralizing the effect of the poison, and not 
the poison itself. 
In the following list will be found the names, both common and chemical, 
of most of the common poisons and their recognized antidotes, the names 
being arranged alphabetically for ready reference : — 
Acetic Acid. — See Acids. 
Acetate of Lead. — See Lead. 
Acids. — A class of substances known generally by a sour taste and chemically 
opposed to alkalies. The common dangerous acids are sulphuric acid (oil of 
vitriol), nitric acid (aqua fortis), hydrochloric acid (muriatic acid), acetic acid, 
and oxalic acid. The antidotes are the harmless alkalies, as powdered chalk, 
magnesia, soap, and lime water. If nothing else be at hand, scrape the plastered 
wall and mix the scrapings with water and drink the mixture. Cream, milk, and 
flour and water will help to allay the burning sensation produced in the mouth and 
throat by the acid. If these acids have been swallowed in an undiluted state in 
any considerable quantity, it will be impossible to save the life of the patient, as 
they are intensely corrosive, destroying the mucous membrane almost the instant 
of contact. Such substances often get by accident on clothes or on the skin. A 
little aqua ammonia if immediately applied will in great measure neutralize their 
effects. If this be not at hand, use strong soap, lye, potash, baking soda, or even 
ashes from the stove will help to neutralize the effect. 
Alkalies. —A class of substances known by their acrid or bitter taste, soapy feel, and 
chemically opposed to acids. The common poisonous alkalies are concentrated lye, 
potash, sal-soda, and ammonia (hartshorn). Acids are the chemical antidotes, 
but, as most of the acids themselves are dangerous, only certain ones should be 
given. Vinegar, lemon juice, sour milk, and sour cider are about the only avail- 
able harmless antidotes. Use these freely. 
Ammonia. — See Alkalies. 
Antimony. — May have been swallowed in the form of tartar emetic, or of black anti- 
mony. Give plenty of strong tea of oak bark, elm bark, currant or blackberry 
leaves. 
Aqua Fortis. — See Acids. 
Arsenic. — May have been taken in the form of Paris green, or rat poison (white 
arsenic, “ratsbane”)- Iron is its chemical antidote, but no convenient'form of 
it will probably be at hand. Give milk and raw egg, or lime water, or flour and 
water, until the doctor comes. Give emetics if possible. 
Bateman’s Drops.—See Opium. 
Bed-bug Poison. — See Mercury. 
Blue-mass or Blue-pill. — See Mercury. 
Calomel. — See Mercury. 
Carbolic Acid and Creosote. — Differing from the common acids. Give sweet oil, or 
castor oil and a mixture of lime, sugar, and water. 
Chloral. — See Chloroform. 
Chloride of Zinc. — See Zinc. 
Chloroform, Ether, and Chloral. — The first two are generally inhaled. Dash cold 
water in the face. Suspend patient by the legs for a few moments; practice 
artificial respiration, as for drowned persons. 
Concentrated Lye. — See Alkalies. 
Copper.— May have been taken in the form of blue vitriol (blue-stone), verdigris, 
food cooked in copper vessels, “ greened pickles.” Give milk and white of eggs, 
and strong tea. Do not give acids. 
Copperas. — See Iron. 
Creosote. — See Carbolic Acid. 
Cyanide of Potassium. — See Prussic Acid. 
Dog Button. — See Strychnia. 
Green Vitriol. — See Iron. 
Greened Pickles. — See Copper. 
Hartshorn. — See Alkalies. 
Hydrochloric Acid. — See Acids. 
Iodine. —Give large quantities of starch and water, or flour and water. 
Iron. — May have been taken in the form of sulphate of iron {copperas, or green 
vitriol). Give magnesia, or baking soda and water. 
Laudanum. — See Opium. 296 
APPENDIX. 
Lead. — In the forms of acetate of lead {sugar of lead), white lead or white paint, red 
lead or red paint. Give Epsom salts, 2 ounces in a pint of water, a wineglassful 
every ten minutes, until several doses have been taken. Painters and others who 
work with these substances are often slowly poisoned, causing what is called “ lead 
colic,” attended with loss of power in the limbs, noticeable in the wrists. Consult 
a physician. 
Lunar Caustic. — See Silver. 
Lye. — See Alkalies. 
Matches. —Children sometimes eat lucifer matches. See Phosphorus. 
Mercury. — In the form of calomel, corrosive sublimate, or bed-bug poison, red precipi- 
tate, vermilion, blue-mass, or blue-pill. Give white of eggs freely, or flour and 
water, or milk, or linseed oil. 
Morphine. — See Opium. 
Muriatic Acid. — See Acids. 
Nitrate of Silver. — See Silver. 
Nitric Acid. — See Acids. 
Opium. — In the form of laudanum or tincture of opium, paregoric, Bateman’s drops, 
soothing sirups, poppy seeds, morphine. Give plenty of strong coffee, which is a 
physiological antidote; put mustard plasters on the calves of the legs; keep patient 
roused by dashing cold water in the face and beating the soles of the feet. 
Oxalic Acid. — Is a solid and resembles Epsom salts, for which it may be mistaken. 
See Acids. 
Oxide of Zinc. — See Zinc. 
Paregoric. — See Opium. 
Paris Green. — See Arsenic. 
Phosphorus.—In the form of matches and rat poison. Give magnesia, chalk, or 
whiting with warm water. Give oil or fat of any kind. 
Poppy Seeds. — See Opium. 
Potash. — See Alkalies. 
Prussic Acid and Cyanide of Potassium. — Very powerful poisons. Little hope of 
saving the patient. Give a teaspoonful of hartshorn in a pint of water. Dash 
water in face. 
Rat Poison. — See Phosphorus and Strychnia. 
Ratsbane. — See Arsenic. 
Red Lead. — See Lead. 
Red Precipitate. — See Mercury.' 
Sal-soda or Washing Soda. — See Alkalies. 
Saltpeter. — Give Hour and water or linseed oil. 
Soothing Sirups.—.See Opium. 
Silver. — In the form of nitrate of silver or lunar caustic. Give salt and water freely, 
then castor oil and flaxseed tea. 
Strychnia. — In the form of rat poison, nux vomica, or dog button, or strychnia. Con- 
vulsions are produced and the body bent backward. Give flaxseed tea. Keep 
quiet and darken the room. Give belladonna or opium under medical advice. 
Sugar of Lead. —See Lead. 
Sulphate of Iron. — See Iron. 
Sulphate of Copper. — See Copper. 
Sulphate of Zinc. — See Zinc. 
Sulphuric Acid. — See Acids. Give very little water, as great heat is produced when 
water and sulphuric acid come together. 
Tartar Emetic. — See Antimony. 
Verdigris. — See Copper. 
Vermilion. — See Mercury. 
Vitriol, Blue.— See Copper. 
Vitriol, Green. — See Iron. 
Vitriol, Oil of.— (Same as sulphuric acid.) See Acids. 
Vitriol, White. — See Zinc. 
White Lead or White Paint. — See Lead. 
Zinc. — In the form of chloride of zinc, white vitriol, or sulphate of zinc, or oxide of 
zinc. Give milk, or magnesia, or chalk and raw eggs. 
All poisons should be plainly labeled and kept out of the reach of children. APPENDIX. 
297 
ANATOMY AND PHYSIOLOGY OF THE VOCAL ORGANS. 
The following is a modified extract from a lecture by Dr. Edward B. Gray 
of Oxford, England, before the London district of the National Phonographic 
Society, December 16, 1891: — 
I will deal first with the general anatomy of the vocal organs, and trust 
that by the help of these diagrams I may be able to present to you an intelli- 
gible outline of it. Allow me to draw attention first to this diagram repre- 
senting a longitudinal section down through the middle of a man’s head and 
neck, from the under 
surface of the skull to 
the top of the windpipe, 
the section passing a 
trifle to the left of the 
central division of the 
nostrils. The part 
marked “ nasal passage ” 
is the irregular cavity of 
the left nostril. T h e 
pharynx is the expanded 
portion at the top of the 
gullet. The cavity of 
the mouth is separated 
from that of the nostrils 
by a vaulted partition 
called the palate. These 
several cavities here 
represented will hence- 
forth be spoken of as the 
nasal, oral, and pharyn- 
geal cavities. 
About the palate I 
must pause to say a few 
words. The word 
“palate” in ordinary 
parlance is rather vaguely 
used. When a man says 
his palate is out of order, 
he means the surface of 
his tongue, and inside of 
his tin >u t h generally. But 
remember that in medical parlance the word has always a restricted meaning, 
being used only of this vaulted partition between the nasal cavity above and 
the oral cavity below. 
This partition is not of the same substance throughout. Its anterior two- 
thirds, called the hard palate, is firmly fixed solid bone ; its posterior one- 
third, called the soft palate, has no bone in it; it is a soft, fleshy swinging 
curtain, with its free edge downwards, and the uvula, like a small, short tassel, 
dangling from its middle. You see it herein section. A full front view of it 
can always be had by looking at the back of your own mouth in the looking- 
glass. 
This soft palate has a great deal to do with speech. Its real use is that of 
a self-acting valve; and according as it is drawn back against the wall of the 298 
APPENDIX. 
pharynx behind, or forward against this part of the tongue in front, so will 
the outgoing current of air from the lungs escape by two very different 
channels — in the one case by the mouth, in the other by the nose, of 
course with corresponding modification of sound. 
We must now leave the nose, mouth, and pharynx for a moment, and 
carry our eyes downwards to the lower part of the first diagram, namely, 
the air tube or larynx. As with the term palate, so the term throat in ordinary 
parlance is employed in a very ill-defined sort of way. A layman almost 
always means by throat the top of his gullet, that is the region between 
and behind the two tonsils. But in medical language, whenever we talk of 
the throat as an organ of speech, we mean, not this part, but the larynx 
or voice box. This is simply an expansion of the upper end of the wind- 
pipe, and, like the windpipe, made of cartilage or gristle. It opens behind 
Diagrams to illustrate the play of the soft 
palate (shaded black) in determining the 
direction of the outgoing air stream. 
into the upper part of the pharynx or gullet, the opening between the two 
being guarded by a flap-valve, called the epiglottis. 
Food, when swallowed, pushes this flap down before it, and the flap 
effectually prevents any of the food entering the larynx. When food goes 
the wrong way, as the saying is, what happens is this: The perfect closure 
of this valve has been somehow prevented, and some of the food has slipped 
into the sensitive larynx, which immediately makes violent and spasmodic 
efforts to expel the intruder. Inside this voice box are the so-called vocal 
cords. Imagine yourselves to be looking down into the larynx from above, 
and you will see the cords stretching across the cavity like a pair of broad, APPENDIX. 
299 
thin, white parallel india-rubber bands. By a special and most elaborate 
machinery of fine muscles these cords can be rendered more or less slack or 
tense, or brought more or less near together, or separated more or less 
widely apart. This play of the vocal cords is represented in the annexed 
diagrams, and can be actually seen and studied by placing a little mirror 
called a laryngoscope at the back of the throat, throwing a strong light 
upon it, and then getting the patient to sing a few notes. 
So much for a rough outline of the anatomy of the parts concerned in 
the production of speech. I must now try to make clear to you the function 
of these several parts, and show how they co-operate in the production 
of speech. 
To understand this you must first remember that all articulate sound 
depends primarily on respiration. The several modulations of voice which 
constitute speech depend upon the play of the various structures just 
described on the outgoing stream of air. The lungs do for our vocal 
machinery just what the bellows does for the church organ. The impor- 
tance of respiration as a factor in speech comes out strikingly, when, 
instead of being calm and even, the expiratory act is hurried, jerky, and 
spasmodic. We then have one of the commonest forms of stammering. 
The first factor, then, in the production of speech is the act of expiration, 
giving rise to an outgoing stream of air from the lungs. The second factor 
is the partial or complete stoppage of that air stream by the interposition of 
a series of barriers in the oral and laryngeal cavities. The third factor is the 
direction of that air stream into the oral or nasal cavity through the valvular 
action of the soft palate. 
A fourth and most important factor is the action of the brain, for before a 
man can utter a single articulate sound the brain has to settle what that 
sound shall be and to put in motion the machinery necessary to produce it. 
Note, therefore, what a very complex matter speech is; for the utterance of 
each sound involves the exercise of (1) cerebration, (2) respiration, (3) 
phonation and articulation, and not only the exercise of each of these highly 
complex functions, but also their harmonious co-operation. 
In pronouncing the several elementary sounds of the English language, if 
you watch closely ypu will note the fact that, while in the articulation of 
some the outgoing air stream is momentarily blocked, in the articulation 
of others it is merely narrowed. In the utterance of the following four pairs of 
consonants, p, b; t, d; ch, j; k, g, there is momentary complete arrest, then 
sudden liberation of the air stream at different points in its passage through 
the mouth. Hence these four pairs of consonants are called explodents. 
Observe that the order from before backwards in which the several barriers 
to the air stream are placed, determines the order in which these consonants 
stand in the Phonetic Alphabet. Thus, when the explosion takes place 
between the lips, p and b are formed. When it takes place at the teeth, or 
(to speak more accurately) between the tip of the tongue and the gums behind 
the upper front teeth, t and d are formed. When the explosion takes place 
yet further back, between the tip of the tongue and the fore part of the roof of 
the mouth, ch and j are formed. Lastly, when it takes place between the root 
of the tongue and the back part of the roof of the mouth, k and g are formed. 
The vocal articulation of each of these pairs of consonants is the same, the 
second letter in each pair being merely the first letter heavily sounded, or 
voiced. 
Then there are four other pairs of consonants, /, v ; th, th; s, z; sh, zh. 
The difference between these and explodents is simply this, that whereas 
explodents are produced by forcing the air stream in a sudden gust through 300 
APPENDIX. 
openings momentarily closed, these are produced by forcing the air in a 
slowed, continuous stream through similar (but slightly modified) openings 
merely narrowed. Hence they are called continuants. They stand in the 
order in which they are placed, because this is the order of the successive 
barriers formed in the mouth from before backwards, at which the outgoing 
air stream becomes narrowed. Like explodents, the continuants go in pairs, 
and for the same reason. 
In the utterance of these eight pairs of consonants, none of the outgoing air 
stream has made its way out through the nose, that little valve, the soft 
palate, having shut off the nasal cavity so as to direct the whole air stream 
through the mouth. 
But there are three other consonants, viz. m, n, ing, in which this arrangement 
is reversed. These three consonants are sounded by the momentary closure in 
succession (1) of the lips, (2) of the fore part of the tongue against the 
fore part of the palate, (3) ot the back part of the tongue against the back 
part of the palate. Now it is most important to observe that these three barriers 
are precisely those which are used for articulating the three explodents b,d,g, and 
the reason of the difference in the resulting sounds is this, that in the one 
case the communication between the nasal cavity and the mouth is left open, 
and in the other case it is closed by the valvular action of the soft palate. 
In sounding nasals the outgoing air stream simply impinges against these 
barriers and escapes into the nasal cavity. In sounding explodents the same 
air stream bursts these barriers, because the closure of the nose by the soft 
palate leaves the air stream no other mode of escape. Hence it is that in 
case of nasal obstructions (as in a very heavy “cold in the head”) our 
attempted nasals become explodents, i.e. m, n, ing become b, d, g. 
A good illustration of this fact, that is, the fact that in nasal obstruction 
attempted nasals become explodents, occurs in “ Oliver Twist.” The wide- 
awake doorkeeper of old Fagin’s den at the “ Three Cripples ” was a certain 
youth named Barney. For some reason or other not determined by Dickens, 
Barney was never able to breathe through his nose. When Noah Claypole 
first knocks at the door of the “ Three Cripples ” Barney says “ Cub id,” and 
in answer to Noah’s inquiry, “ Is this the ‘ Three Cripples ? ’” he informs him 
“ That is the dabe of this ’ouse.” Again, when Toby Crackitt, spying Oliver 
in the Jew’s den, asks Barney who he is, Barney says, “Wud of Bister 
Fagid’s boys.” Barney always spoke of Fagin as “ Bister Fagid,” and Nancy 
as “ Biss Dadsy.” 
So much for the articulation of explodents, continuants, and nasals. 
The only consonants now remaining are the liquids, l and r, and aspirate h. 
L and r are sounded by forcing the outgoing air stream between the tip of 
the tongue and the roof of the mouth. In point of articulation, therefore, 
l and r are voiced continuants; but, like the nasals, not having in our 
language corresponding breath consonants to pair with them, they form a 
special group. They are called liquids from the ease with which in pronunci- 
ation they follow other consonants, and, as it were, melt with them into com- 
binations such as the pi and pr series. 
The only other remaining consonant is the aspirate h. This calls for no 
remark; its production being, as its name indicates, a mere sigh, or expira- 
tory effort. So much for consonants. 
Now, following our plan of proceeding from before backwards and down- 
wards, we come to the last barrier in the way of the expired air, and that is 
the vocal cords. It is the rush of the air stream through the varying width 
of the chink between the cords — in sufficient force to make them vibrate — APPENDIX. 
301 
which primarily gives rise to the simple long vowels — ah, eh, ee, aw, oh, oo, 
and their corresponding short sounds — a, e, i, o, u, do. 
Now, observe that in the mechanism of their production vowels are by no 
means as simple as they may at first appear. Books will tell you summarily 
that vowels are formed in the larynx and consonants in the mouth. This is 
by no means a correct representation of the case. It is true that vowels are 
primarily formed at the vocal cords in the larynx, but they are, one and all, 
more or less modified by simultaneous adaptations of the aperture of the lips 
and the position of the tongue. In the sounding of each vowel both these 
agencies are at work, but in unequal degrees, ah, eh, ee depending mainly on 
the position of the tongue as regards the palate, while aw, oh, oo depend 
mainly on the regulation of the aperture of the mouth by the lips. In ah, eh, 
ee, there is gradual protrusion and elevation; in aw, oh, oo gradual retraction 
and depression of tongue. On this natural law is based Mr. Pitman’s classifi- 
cation of simple vowels into palatal and labial, each series commencing with 
the most open and ending with the most closed sound. 
The main principle of this classification is unassailable, but I venture to 
think that the palatal group would be more appropriately named lingual, for 
this simple reason, that in the oral modification of ah, eh, ee the tongue does 
all the work, while the palate remains passive. If the one group of vowels 
is called labial because the lips play the chief part in their production, the 
other group for similar reason should be called lingual.