Louis John Rettger.

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Professor of Biology in The Indiana State Normal School.



Copyrighted, 1898,




There are two extremes open in writing a brief treatise
on any natural science. One is to state briefly and explic-
itly those facts which are seriously questioned by no one.
It is to enumerate and tabulate what is definitely known
about the subject. In the field of animal physiology there
is much which is "settled" information, and which it is be-
lieved, will not be materially changed by the developments
of the future. Most of the gross anatomy is finished, by no
means all, but many points in histology are determined,
while in pure physiology there are fewer things that are con-
sidered explained. Thus the phenomena of respiration and
the dynamics of the blood flow are to a very large extent
known in terms of chemical and physical laws. To limit a
book to this would be to make it stereotyped, dead, and leave
the reader with the impression that physiology like Sanskrit
was finished, and like every finished problem had no longer
a living interest of its own. Most of the ordinary text-
books err on this side. They state ex cathedra, fact after
fact, they seldom give the reasons which have led physi-
ologists to adopt the views in question, and they seldom
leave the idea that many things are still being studied with
the hope that more study will give new light. Most text-
books leave the mind of the student with the belief that all
has been told, that there is nothing more to add, and that
therefore there is no need for him to try to improve on the
text-book, by making his own observation. The feeling of
the authority of the text-book in physiology has robbed
many a student of the desire to investigate the subject
further. L,ike the Scholastics of the Middle Ages they turn
to the book as to Aristotle, fully convinced that all know-
ledge is contained in it, and that what is not contained is
impossible of access.

The other extreme is to give in detail all the scientific
controversies of the past and present. It is to state indis-
criminately pros and cons until the conviction settles over
one that nothing is definite and all is confusion. Especially
true is this when these conflicting views are at once pre-
sented to the beginner in the subject.



There are in physiology, as, possibly, in all other
sciences, many problems at present which admit of different
interpretations, and which must be referred to the investi-
gations of the future for their correctness or their faultiness.
It would not be treating the reader right to shower him
with all sides of these questions, but the author has endeav-
ored to present that view in each case which seems most
generally accepted by scientific men, and awaiting future
verifications to show the value of the claim. By taking
this median course it is believed that the book will give to
its readers all of the main known facts, and in addition
acquaint them with many of those questions which are now
demanding the attention of physiologists. This will put
the science of physiology in its true light, it will show that
it is a living science, still at work trying to interpret living
problems. While it will show the present limitations of
our knowledge it will suggest future possibilities.

It is hoped that the study of this book may result in a
more lively appreciation of physiological phenomena, and
an added interest in teaching the subject in our common

It has been the aim to choose the illustrations for this
book with the greatest possible care. They have been
selected from quite a number of sources, and the proper
credit has in each case been given with every figure. Quite
a number of the histological illustrations are from Schafer's
Essentials of Histology. The author desires hereby to
thank Messrs. L,ongmans, Green & Company, the publish-
ers of that prince of text-books, Quain's Anatomy, for their
permission to reproduce several of the illustrations found
therein. The colored plates on the circulation of the blood
have been made possible by their courtesy. The author is
also under many obligations to D. Appleton & Company,
publishers of Osier's Practice of Medicine, for permission
to reproduce the colored plates illustrative of the nervous

Terre Haute, Indiana,
Aug. 12, 1898.



Introduction 1

An Epitome of the History of Physiology.

Hippocrates. Aristotle. Praxagoras. Herophilus and the Alex-
andrian School. " Galen. Vesalius. Servetus. Fabricius.
Harvey. Later investigators 5

The Cell and its Life.

Historical view. A typical cell. The division of the cell. Physi-
cal basis of heredity 22

The Teaching of Physiology and the Public Health.

History of Sanitation. Bacteriology. Bacteria. How germs
produce disease. Theories of immunity. Unsolved prob-
lems. Practical guidance. Rules of Indiana Board of>
Health 29

General Definitions.

Anatomy. Comparative Anatomy. Histology. Embryology.

Classification 46

The Blood.

General points. Amount. Composition. Red corpuscles, (size,
form, color, surface, composition, consistency, origin, de-
struction). Haemoglobin. Spectrum of haemoglobin. Blood
crystals. White corpuscles. Blood plates. Blood plasma.

Coagulation. Serum. Phenomena of osmosis 49



The Supporting Tissues. PAGE.

The Skeleton. Minute structure of bone. Origin and growth of
bone. Process of ossification. Chemical composition of
bone. Cartilages. Connective tissues proper. Humors.
Formation of cartilage and connective tissues. Hygiene of
supporting tissues. Joints. Ligaments 75

Muscles and the Phenomena of Contraction.

Kinds of Muscles. Voluntary muscles. Minute structure. Growth
of muscle. Finer structure of the muscle fibre. Plain mus-
cular tissue. Cardiac muscle. Chemistry of muscle. Elas-
ticity. Muscle stimuli. A single contraction. Tetanus.
Wave of contraction. Lifting power of muscles. Changes
in volume. Muscle fatigue-. Blood supply of muscles.
Electrical phenomena in muscles. Wave of negative varia-
tion. Rigor mortis. Source of muscular energy. Mechan-
ics of muscles. Levers. Mathematics of levers. Hygiene
of muscles 112

The Circulation.

General arrangement. Route of one complete circulation. The
heart (position, coverings, cavities, vessels arising from,
valves of heart). The arterial system. The venous system.
The pulmonary circulation. The portal circulation. His-
tology of arteries, veins and capillaries. Phenomena of the
heart's beat (rate, systole, diastole, filling of heart, sounds
of heart). Cardiograms. Pathological sounds of the heart.
Amount of blood forced out per beat. Energy and work
of the heart. Innervation of the heart. The dynamics of
the blood stream. Arterial pressure. Venous pressure.
Pressure in capillaries. Rate of blood flow. Time of one
complete circulation. Pulse (cause, kinds of, rate, meas-
urements of). Innervation of blood-vessels. Changes in
the circulation at birth 146

The Lungs and the Processes of Respiration.

Anatomy of respiratory system. Pathological conditions of sys-
tem. Mechanics of respiration. Ventilation. Chemistry of
respiration. Phenomena of external respiration. Dalton's
law of gases. The role of the red corpuscles. Phenomena
of internal respiration. Elimination of carbon dioxide. The
innervation of the respiratory system 202



The Larynx and the Production of Articulate Speech.

Anatomy of larynx. Manipulation of larynx in the production of

sounds. Range of human voice. Vowels. Consonants 239

Glands and the General Physiology of Secretion.

Historical. Secretion. Anatomy of glands. Process of secre-
tion. Histological changes in secreting cells. Innervation
of glands .. 249

The Digestive Organs and their Anatomy.

Mouth. Teeth. Structure of a typical tooth. Hygiene of the
teeth. Development and origin of the teeth. Tongue.
Papillae. Taste-bulbs. Gullet. Stomach. Gastric glands.
Small intestine. Villi. Large intestine. Mucous glands.
Pancreas. Liver. Thyroid gland. Spleen. Adrenal bodies.
Thymus gland. Carotid gland. Coccygeal gland. Pituitary
body 264

Foods and their Physiological Value.

Losses of the body. Classes of foods. A mixed diet. Relative
amounts in an average daily diet. Flavors, condiments,
stimulants. Alcohol. Physiological effects of alcohol 308

Digestion and the Digestive Agents.

Historical. Saliva and salivary digestion. Theory of hydrolysis.
Stomach and gastric digestion. Pepsin. Pancreatic juice.
Trypsin. Amylopsin. Steapsin. Bile. Bile salts. Bile
pigments. General function of bile. Intestinal juice. ... 327

Absorption and the Routes of Food.

Absorption of peptones. Absorption of the sugars. Absorption
of the fats. General physiology of the liver. Glycogen.
Hepatic action on albumens. Formation of urea 352



Nutrition and the Metabolic Changes in the Tissues.

General questions. Uses of the classes of foods. Use of proteids.
Disintegration of living 1 tissue. Formation of urea. For-
mation of C0 2 . Reconstruction of living tissue. Use of fats
and sugars. Nutritive equilibrium. Kreatin. Kreatinin.
Inter-relation of fats and carbohydrates 365

The Maintenance of the Animal Heat.

Normal temperature of body. Warm-blooded, cold-blooded ani-
mals. Variations in temperature. Conditions affecting the
temperature. The regulation of the temperature. Thermo-
genic nerves. Quantitative determinations of the source
and expenditure of heat. The amount of heat lost by the
body 376


The Kidneys, the Skin and the General Physiology of

Kidneys. Anatomy of urinary organs. Circulation through kid-
neys. Uriniferous tubules. Urine. Composition of urine.
Source of the urea. Skin. Epidermis. Dermis. Nails.
Hairs. Sebaceous glands. Sweat glands. Nerves of sweat
glands. Composition of sweat 385

The Anatomy and Physiology of the Nervous System.

Nerve systems. Nervous elements. Nerves. Nerve Trunks.
Plexuses. Nerve centers. Ganglia. Dura mater. Pia mater.
Arachnoid membrane. Spinal cord. Spinal nerves. Brain.
Weight of brain. Convolutions. Interior of brain. Ven-
tricles. Cranial nerves. Sympathetic system. Histology
of nervous system. Neurons. Minute structure of nerves
and nerve trunks. Gray fibres. Development of nerves.
Regeneration of nerves. Neuroglia. Nerve stimuli. Nature
of a nervous impulse. Kinds of nerve fibres. Finer archi-
tecture of central nervous system. Arrangement of motor
neurons. Arrangement of sensory neurons. Medulla.
Function of cerebellum. Function of midbrain. Function
of cerebrum. Localization of centers in the brain. Physi-
ological topography of the brain. Consciousness. Sleep.
Hypnotic phenomena. Time relations in psychic phe-
nomena. Personal equation 409


The Organs of Special Sense. PAGE.

Common sensations. Special sensations. Structure of an organ
of special sense. Neurosis. Psychosis. Development of
the special senses. The objectification of our sensations.
The relation between neurosis and psychosis. The psycho-
physical law. Confusion of sensations and inferences from
sensations 469

Touch, Temperature, Muscular Sense, Taste, Smell.

The anatomy of the end organs of touch. Pacinian corpuscles.
Tactile cells. End bulbs. Touch corpuscles. The absolute
touch sensitiveness. The power of localization and the touch
areas. The sense of temperature. The muscular sense.
The sense of taste. Taste bulbs. The nature of a taste
sensation 477

The Ear.

The nature of sound. The production of sound. The range of
the number of vibrations in the production of sound. The
transmission of sound in the air and its velocity in the same.
Reflection and refraction of sound. The physical proper-
ties of sound. Harmony. Sympathetic vibrations. The
external ear. The middle ear. The membranous ear.
Histology of the membranous labyrinth. The minute struc-
ture of the membranous cochlea. The functions of the in-
dividual parts of the membranous ear. The localization of
sound 494

The Eye and the Physiology of Vision.

Historical. The nature of light. The rate of transmission. The
number of vibrations in waves of light. The spectrum.
Complementary colors. The colors of objects by transmitted
or reflected light. The refraction of light and the property
of lenses. The formation of images by lenses. The anat-
omy of the eye (eyebrows, eyelids, lachrymal apparatus,
muscles of the eyeball, the globe of the eye, sclerotic coat,
choroid coat, ciliary muscles and the muscles of accomoda-


tion, optic nerves, microscopic structure of the retina). The
eye as a purely physical instrument. The normal or emme-
tropic eye (myopia, hypermetropia, astigmatism, cataract,
spherical aberration, chromatic aberration, muscae-voUtan-
tes, presbyopia) . The manipulation of the eye as an opti-
cal instrument. How do we focus the eye? The dioptrics
of the eye. The luminosity of eyes. The physiology of
color sensation. Color blindness. The Young-Helmholtz
theory. Normal or trichromatic eyes. The Hering theory.
After-images. Explanation of negative after-images.
Double vision. The advantages of two eyes. Optical illu-
sions . . 529


What are the reasons that entitle the subject of physiol-
ogy to a place in the common school curriculum? There
are now so many subjects, on the educational value of
which most educators are agreed, that unless physiology
can do for the student what these do, it ought to give way
to better fields of study.

In many cases no doubt it is taught simply because it is
prescribed by law, and its injunctions are not questioned.
In other cases its study is considered desirable, or even
necessary, because physiology concerns itself so largely
with hygienic considerations, and so is believed to exert a
helpful influence on the general health. Possibly this is
the main purpose our legislators had in mind when, by
statute, physiology was made one of the common school
branches. No one will deny the value, in fact the neces-
sity, of having clear conceptions of hygienic rules and
thoroughly understanding the laws of sanitation. It is the
author's firm belief that if the knowledge of the nature of
contagious and infectious diseases and of the means of
their spreading, was more generally possessed, perfected
sanitation would be declared a necessity, and the public
health would be greatly improved. Such a result would
repay a thousand times the cost of teaching such practical
information. It is however a question whether it usually
pays to have the study of physiology degenerate into formal
rules of health, and recipes for disease. Such formal,
theoretical knowledge seldom becomes of practical benefit.
Most of us eat what our pocketbooks can afford and what
experience shows agrees with us. We regulate our exer-
cise by the amount of time available, and our inclination to
take it. The desirability of bathing arises from something
deeper than a mere intellectual perception of its value.



The tramp probably possesses, in some instances, a theoret-
ical knowledge of the efficacy of soap and water, but it
does not therefore become a practical belief.

In teaching small children it is of course desirable to
make almost all the work of this hygienic character.
Physiology is a science that pre-supposes some knowledge
of physics and chemistry, and that cannot be assumed in
really elementary classes. In addition small children have
a morbid curiosity aroused when dealing with anatomical
structures that is frequently productive of more evil than
good. But with advanced classes physiology can be studied
to the greatest advantage, provided that we do so in a
scientific way. While in a strict sense physiology does not
at all include anatomy, either gross or minute, yet as gen-
erally conceived it is made to include this, and in such a
sense it is used by the author. While pure physiology is
a science of experiments, like physics and chemistry, and
not a science of observation like botany and zoology, and
as from the difficulty of the experiments, not many of them
can be repeated by the student himself, yet there are
numerous simpler experiments of deepest physiological
import which the student can perform for himself. Some
experiments in artificial digestion with prepared extracts,
the nature of the flow of liquids in iron and rubber tubes to
illustrate circulation, the phenomena of blood coagulation,
and finally the many experiments to be made in the study
of the special senses, all these will afford abundant oppor-
tunities to perform experiments of the highest educational
value. But it is when we include anatomy that the oppor-
tunities are greatest. It is never necessary in elementary
instruction to call to aid vivisections, or even ordinary
dissections of a nature often calculated to be repulsive.
Let all these be proscribed. But the meat market itself
will afford a multiplicity of material which will serve
to illustrate all the more important fields of anatomy.
Now it is believed that while a large part of the matter of
physiology must be informational, and although this is often


of the greatest value, the best thing this subject can do for
the student is to allow him to make his own observations as
far as possible, and to make his own interpretations of
experiments from related facts out of his own experience.
There is not so much educational value in knowing that the
heart possesses auricles, ventricles and valves, as there is
in finding and understanding them when a real heart is being
examined. There is an endless difference in mental value
between learning a few curious things about the brain from
the book or a cheap model, or even the description of a
teacher, and in studying for ourselves, in detail, the varied
anatomy of a real sheep's brain. One leaves us with hazy
and dim ideas, the only real, tangible thing of which are the
words to symbolize them, but the other results in real,
definite, and lasting information. To have dissected out the
salivary glands on the sheep's head, furnished by the meat
market ; to have seen the Eustachian tube ; to have cut out
the tonsils ; observed the large circumvallate papillae on the
tongue ; to have seen the lens and separated the coats of the
eye ; to have hunted for and found the middle ear with its
chain of bones, possibly to have laid open the cochlea; to
have seen all these things on a single sheep's head, will be
of more lasting benefit and real educational worth than the
ability to repeat from memory a chapter at a time of the
latest edition of Quain's Anatomy. If, to carry the sug-
gestion a little further, the student could observe and study
with his own eyes the sympathetic system as it hangs dis-
played in every meat market, if he could but see one
ganglion, one nerve trunk, and really learn to know it, if
he could grasp with the fingers of his hand as well as those
of his mind a single typical gland, crush with his thumb but
one lymphatic nodule to know it, if in short he could get
a living knowledge of the more important structures alone,
he would not only have acquired facts which are indelible
and can be turned to practical advantage, but he will have
acquired a discipline in their acquisition which will give
added power to the entire mind. Furthermore, and possibly


best of all, he is acquiring new facts in the way lie will be
obliged to acquire them when he leaves the school, and
when there will no longer be a teacher to diagram every
difficulty on the board in colored crayons, and when the
student will no longer be carried each day ' ' three pages in

By making his own actual observations on actual tan-
gible material he is not only training his powers of observa-
tion which are directly concerned, but by the care required
to verify his observations, and by strict reasoning of the
mind to properly interpret his observations, he is developing
all those faculties of mind which are required in the acqui-
sition of any new truth. He will learn what it often costs
to make but one point, he will see what painstaking efforts
it frequently requires to establish but one new fact, and he
will not be discouraged when later on he finds it hard to
make progress. He will know that to learn but one point
as it ought to be learned is making more real progress than
to have many poured into him. He will have somewhat of
a criterion by means of which to gauge his own pace. It
is certainly an attitude of mind brought about by scientific
study not to accept too quickly what seems still unproved,
be it from the assurances of the patent-medicine quack to
the politician with his latest schemes on finance. Huxley
compared knowledge with the virus of vaccination. When
the virus is fresh, when it comes directly from its original
source, it is wonderfully potent, but passed through the
tissues of other animals it is gradually weakened and may
finally have no effect at all. So knowledge gained first-
hand, from the objects themselves, from the experiments
themselves, is wonderfully potent, but passed through the
tissues of several text-books or handed down through several
teachers, it is gradually weakened until finally when it is
administered it is too weak to save us from the intellectual
epidemics of the day.



The word physiology now used to designate this and
kindred subjects, has a very remote origin. Etymologi-
cally it means a discourse on nature, from the Greek words
physis (0"'<H?), meaning nature, whence the word physical,
and logos (?-<w), meaning a discourse. In this original
sense it was employed by the earliest writers to include all
the natural sciences. Soon astronomy was set off as a spe-
cial science, and the term restricted to all subjects that
deal with natural phenomena and natural objects close at
hand. Little by little as human knowledge widened,
and the accumulated observations and experiments in
any one field became considerable, this field was sepa-
rated from the general study of nature, physiology, and
designated by its own peculiar name. In this way the
accumulating facts in the domain of chemistry gave rise to
the alchemy of the Middle Ages, and when later alchemy
was stripped of its superstitions and fancies, it rose to the
dignity of the science of chemistry. Soon purely physical
facts were separated off as the science of natural philosophy
and have become the science of physics. This eliminating
process has continued with the progress of science until the
original term physiology, which means the study of entire
nature, has been contracted so as to apply only to that
science which seeks to explain vital phenomena, be it in
plant or in animal.

Etymologically physiology is the parent science and all
others outgrowths of it. But not only in an etymological
sense is physiology of early origin. While logically phys-
iology follows physics, chemistry, botany and zoology, and



presupposes them at many steps, yet historically almost the
exact opposite is true. It is a trait of the human mind ap-
parently to attack a problem by attempting at once the
explanation of its deepest questions. Thales, Anaximan-
der, Anaximenes, Heraclitus and other early Grecian phil-
osophers busied themselves with trying to explain the ulti-
mate essence of things before the world had made even
the first real attempt to learn something of the things them-


Ancient writers cite Hippocrates of Macedon as the
person in whom physiological observations began. He is
often called the " Father of Medicine." Hippocrates was
a contemporary of Socrates and Plato, and he is especially

Online LibraryLouis John RettgerStudies in advanced physiology → online text (page 1 of 46)