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The Origin and Nature of the Emotions; Miscellaneous Papers

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Title: The Origin and Nature of the Emotions; Miscellaneous Papers

Author: George Washington Crile


        
Release date: March 1, 1998 [eBook #1233]
                Most recently updated: April 2, 2015

Language: English

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*** START OF THE PROJECT GUTENBERG EBOOK THE ORIGIN AND NATURE OF THE EMOTIONS; MISCELLANEOUS PAPERS ***
Ver.04.29.93*END*




THE ORIGIN AND NATURE

of the

EMOTIONS

Miscellaneous Papers

BY

GEORGE W. CRILE, M.D.

PROFESSOR OF SURGERY, SCHOOL OF MEDICINE, WESTERN RESERVE UNIVERSITY
VISITING SURGEON TO THE LAKESIDE HOSPITAL, CLEVELAND

EDITED BY
AMY F. ROWLAND, B. S.




PREFACE


IN response to numerous requests I have brought together into this volume
eight papers which may serve as a supplement to the volumes previously
published[*] and as a preface to monographs now in preparation.


[*] Surgical Shock, 1899; Surgery of the Respiratory System, 1899;
Problems Relating to Surgical Operations, 1901; Blood Pressure
in Surgery, 1903; Hemorrhage and Transfusion, 1909;
Anemia and Resuscitation, 1914; and Anoci-association, 1914
(with Dr. W. E. Lower).


In the first of these addresses, the Ether Day Address, delivered at
the Massachusetts General Hospital in October, 1910, I first
enunciated the Kinetic Theory of Shock, the key to which was found
in laboratory researches and in a study of Darwin's "Expression
of the Emotions in Man and in Animals," whereby the phylogenetic
origin of the emotions was made manifest and the pathologic
identity of surgical and emotional shock was established.
Since 1910 my associates and I have continued our researches through--
(a) Histologic studies of all the organs and tissues of the body;
(b) Estimation of the H-ion concentration of the blood in the emotions
of anger and fear and after the application of many other forms of stimuli;
(c) Functional tests of the adrenals, and (d) Clinical observations.

It would seem that if the striking changes produced by fear
and anger and by physical trauma in the master organ of the body--
the brain--were due to WORK, then we should expect to find
corresponding histologic changes in other organs of the body as well.
We therefore examined every organ and tissue of the bodies of animals
which had been subjected to intense fear and anger and to infection and
to the action of foreign proteins, some animals being killed immediately;
some several hours after the immediate effects of the stimuli had passed;
some after seances of strong emotion had been repeated several
times during a week or longer.

The examination of all the tissues and organs of these animals
showed changes in three organs only, and with few exceptions in all
three of these organs--the brain, the adrenals, and the liver.
The extent of these changes is well shown by the photomicrographs
which illustrate the paper on "The Kinetic System" which is included
in this volume.  This paper describes many experiments which show
that the brain, the adrenal, and the liver play together constantly
and that no one of these organs--as far at least as is indicated
by the histologic studies--can act without the co-operation
of the other two.

Another striking fact which has been experimentally established
is that the deterioration of these three organs caused by emotion,
by exertion, and by other causes is largely counteracted,
if not exclusively, during sleep.  If animals exhausted by the continued
application of a stimulus are allowed complete rest for a certain
number of hours, _*without sleep_, the characteristic histologic
appearance of exhaustion in the brain, adrenals, and liver is not
altered notably, whereas in animals allowed to sleep for the same
number of hours the histologic changes in these organs are lessened--
in some cases obliterated even.

This significant phenomenon and its relation will be dealt with in
a later monograph.

Many of the arguments and illustrations by which the primary
premises were established are repeated--a few in all--many in
more than one of these addresses.  It will be observed, however,
that the APPLICATION of these premises varies, and that their
SIGNIFICANCE broadens progressively.

In the Ether Day Address the phylogenetic key supplied by Darwin was
utilized to formulate the principle that the organism reacts as a unit
to the stimuli of physical injury, of emotion, of infection, etc.
To the study of these reactions (transformations of energy)
the epoch-making work of Sherrington, "The Integrative Action
of the Nervous System," gave an added key by which the dominating
role of the brain was determined.  Later the original work
of Cannon on the adrenal glands gave facts, and an experimental
method by which Darwin's phylogenetic theory of the emotions
was further elaborated in other papers, especially in the one
entitled "Phylogenetic Association in Relation to the Emotions,"
read before The American Philosophical Society in April, 1911.
GEORGE W. CRILE.  CLEVELAND, OHIO, _February, 1915_.



CONTENTS PAGE PHYLOGENETIC ASSOCIATION IN RELATION TO CERTAIN MEDICAL
PROBLEMS. . . . . . . . . . . . . . . . . . . . . . . . . . .1

PHYLOGENETIC ASSOCIATION IN RELATION TO THE EMOTIONS . . . .
55 PAIN, LAUGHTER, AND CRYING. . . . . . . . . . . . . . . . . 77

THE RELATION BETWEEN THE PHYSICAL STATE OF THE BRAIN-CELLS AND
BRAIN FUNCTIONS-EXPERIMENTAL AND CLINICAL . . . .111

A MECHANISTIC VIEW OF PSYCHOLOGY . . . . . . . . . . . . . .127

A MECHANISTIC THEORY OF DISEASE. . . . . . . . . . . . . . .157

THE KINETIC SYSTEM . . . . . . . . . . . . . . . . . . . . .173

ALKALESCENCE, ACIDITY, ANESTHESIA--A THEORY OF ANESTHESIA.  .227

INDEX. . . . . . . . . . . . . . . . . . . . . . . . . . . .237
THE ORIGIN AND NATURE OF THE EMOTIONS

PHYLOGENETIC ASSOCIATION IN RELATION TO CERTAIN MEDICAL PROBLEMS[*]


[*] Address delivered at the Massachusetts General Hospital on
the sixty-fourth anniversary of Ether Day, Oct. 15, 1910.


The discovery of the anesthetic properties of ether and its practical
application to surgery must always stand as one of the great
achievements of medicine.  It is eminently fitting that the anniversary
of that notable day, when the possibilities of ether were first
made known to the world, should be celebrated within these walls,
and whatever the topic of your Ether Day orator, he must fittingly
pause first to pay tribute to that great event and to the master
surgeons of the Massachusetts General Hospital.  On this occasion,
on behalf of the dumb animals as well as on behalf of suffering humanity,
I express a deep sense of gratitude for the blessings of anesthesia.

Two years ago, an historic appreciation of the discovery of ether
was presented here by Professor Welch, and last year an address
on medical research was given by President Eliot.  I, therefore,
will not attempt a general address, but will invite your
attention to an experimental and clinical study.  In presenting
the summaries of the large amount of data in these researches,
I acknowledge with gratitude the great assistance rendered by
my associates, Dr. D. H. Dolley, Dr. H. G. Sloan, Dr. J. B. Austin,
and Dr. M. L. Menten.[*]


[*] From the H. K. Cushing Laboratory of Experimental Medicine,
Western Reserve University, Cleveland.


The scope of this paper may be explained by a concrete example.
When a barefoot boy steps on a sharp stone there is an immediate discharge
of nervous energy in his effort to escape from the wounding stone.
This is not a voluntary act.  It is not due to his own personal experience--
his ontogeny--but is due to the experience of his progenitors
during the vast periods of time required for the evolution
of the species to which he belongs, _i.  e_., his phylogeny.
The wounding stone made an impression upon the nerve receptors
in the foot similar to the innumerable injuries which gave origin
to this nerve mechanism itself during the boy's vast phylogenetic or
ancestral experience.  The stone supplied the phylogenetic association,
and the appropriate discharge of nervous energy automatically followed.
If the sole of the foot be repeatedly bruised or crushed by a stone,
shock may be produced; if the stone be only lightly applied,
then the consequent sensation of tickling causes a discharge of
nervous energy.  In like manner there have been implanted in the body
other mechanisms of ancestral or phylogenetic origin whose purpose
is the discharge of nervous energy for the good of the individual.
In this paper I shall discuss the origin and mode of action of some
of these mechanisms and their relation to certain phases of anesthesia.

The word anesthesia--meaning WITHOUT FEELING--describes accurately
the effect of ether in anesthetic dosage.  Although no pain
is felt in operations under inhalation anesthesia, the _*nerve
impulses excited by a surgical operation still reach the brain_.
We know that not every portion of the brain is fully anesthetized,
since surgical anesthesia does not kill.  The question then is:
What effect has trauma under surgical anesthesia upon the part
of the brain THAT REMAINS AWAKE?  If, in surgical anesthesia,
the traumatic impulses cause an excitation of the wide-awake cells,
are the remainder of the cells of the brain, despite anesthesia,
affected in any way?  If so, they are prevented by the anesthesia from
expressing that influence in conscious perception or in muscular action.
Whether the ANESTHETIZED cells are influenced or not must be determined
by noting the physiologic functions of the body after anesthesia has
worn off, and in animals by an examination of the brain-cells as well.
It has long been known that the vasomotor, the cardiac, and the respiratory
centers discharge energy in response to traumatic stimuli applied
to various sensitive regions of the body during surgical anesthesia.
If the trauma be sufficient, exhaustion of the entire brain
will be observed after the effect of the anesthesia has worn off;
that is to say, despite the complete paralysis of voluntary
motion and the loss of consciousness due to ether, the traumatic
impulses that are known to reach the AWAKE centers in the medulla
also reach and influence every other part of the brain.
Whether or not the consequent functional depression and the morphologic
alterations seen in the brain-cells may be due to the low blood-pressure
which follows excessive trauma is shown by the following experiments:
The circulation of animals was first rendered STATIC by over-transfusion,
and was controlled by a continuous blood-pressure record on a drum,
the factor of anemia being thereby wholly excluded during the application
of the trauma and during the removal of a specimen of brain tissue
for histologic study.  In each instance, morphologic changes
in the cells of all parts of the brain were found, but it required
much more trauma to produce brain-cell changes in animals whose
blood-pressure was kept at the normal level than in the animals
whose blood-pressure was allowed to take a downward course.
In the cortex and in the cerebellum, the changes in the brain-cells
were in every instance more marked than in the medulla.

There is also strong NEGATIVE evidence that traumatic impulses
are not excluded by ether anesthesia from the part of the brain
that is apparently asleep.  This evidence is as follows:
If the factor of fear be excluded, and if in addition the traumatic
impulses be prevented from reaching the brain by cocain[*] blocking,
then, despite the intensity or the duration of the trauma within
the zone so blocked, there follows no exhaustion after the effect
of the anesthetic disappears, and no morphologic changes are noted
in the brain-cells.


[*] Since the presentation of this paper, novocain has been
substituted for cocain in operations under anoci-association.


Still further negative evidence that inhalation anesthesia offers
little or no protection to the brain-cells against trauma is derived
from the following experiment:  A dog whose spinal cord had been
divided at the level of the first dorsal segment, and which had
then been kept in good condition for two months, showed a recovery
of the spinal reflexes, such as the scratch reflex, etc.  Such an
animal is known as a "spinal dog."  Now, in this animal, the abdomen
and hind extremities had no direct nerve connection with the brain.
In this dog, continuous severe trauma of the abdominal viscera and of
the hind extremities lasting for four <p 5-7> hours was accompanied
by but slight change in either the circulation or in the respiration,
and by no microscopic alteration of the brain-cells (Fig. 1). Judging
from a large number of experiments on NORMAL dogs under ether,
such an amount of trauma would have caused not only complete
physiologic exhaustion of the brain, but also morphologic alterations
of all of the brain-cells and the physical destruction of many
(Fig. 2). We must, therefore, conclude that, although ether anesthesia
produces unconsciousness, it APPARENTLY PROTECTS NONE OF THE BRAIN-CELLS
against exhaustion from the trauma of surgical operations; ether is,
so to speak, but a veneer.  Under nitrous oxid anesthesia there is
approximately only one-fourth as much exhaustion as is produced by equal
trauma under ether (Fig. 3). We must conclude, therefore, either that
nitrous oxid protects the brain-cells against trauma or that ether
predisposes the brain-cells to exhaustion as a result of trauma.
With these premises let us now inquire into the cause of this
exhaustion of the brain-cells.


The Cause of the Exhaustion of the Brain-cells as a Result of Trauma
of Various Parts of the Body under Inhalation Anesthesia


Numerous experiments on animals to determine the effect of ether
anesthesia _per se_, _i.  e_., ether anesthesia without trauma,
showed that, although certain changes were produced, these included
neither the physiologic exhaustion nor the alterations in the
brain-cells which are characteristic of the effects of trauma.
On turning to the study of trauma, we at once found in the behavior
of individuals as a whole under deep and under light anesthesia
the clue to the cause of the discharge of energy, of the consequent
physiologic exhaustion, and of the morphologic changes in the brain-cells.

If, in the course of abdominal operations, rough manipulations
of the parietal peritoneum be made, there will be frequently
observed a marked increase in the respiratory rate and an increase
in the expiratory force which may be marked by the production
of an audible expiratory groan.  Under light ether anesthesia,
severe manipulations of the peritoneum often cause such vigorous
contractions of the abdominal muscles that the operator is greatly
hindered in his work.

Among the unconscious responses to trauma under ether anesthesia
are purposeless moving, the withdrawal of the injured part, and,
if the anesthesia be sufficiently light and the trauma sufficiently
strong, there may be an effort toward escape from the injury.
In injury under ether anesthesia every grade of response may be seen,
from the slightest change in the respiration or in the blood-pressure
to a vigorous defensive struggle.  As to the purpose of these
subconscious movements in response to injury, there can be no doubt--
THEY ARE EFFORTS TO ESCAPE FROM THE INJURY.

Picture what would be the result of a formidable abdominal operation
extending over a period of half an hour or more on an unanesthetized
human patient, during which extensive adhesions had been broken up,
or a large tumor dislodged from its bed!  In such a case,
would not the nervous system discharge its energy to the utmost
in efforts to escape from the injury, and would not the patient suffer
complete exhaustion?  If the traumata under inhalation anesthesia
are sufficiently strong and are repeated in sufficient numbers,
the brain-cells are finally deprived of their dischargeable nervous
energy and become exhausted just as exhaustion follows such strenuous
and prolonged muscular exertion as is seen in endurance tests.
Whether the energy of the brain be discharged by injury under anesthesia
or by ordinary muscular exertion, identical morphologic changes are
seen in the nerve-cells. In shock from injury (Fig. 2), in exhaustion
from overwork (Hodge and Dolley) (Fig. 4), and in exhaustion from pure fear
(Fig. 5), the resultant general functional weakness is similar--
in each case a certain length of time is required to effect recovery,
and in each there are morphologic changes in the brain-cells. It
is quite clear that in each of these cases the altered function
and form of the brain-cells are due to an _*excessive discharge
of nervous energy_.  This brings us to the next question:
What determines the discharge of energy as a result of trauma
with or without inhalation anesthesia?


The Cause of the Discharge of Nervous Energy as a Result of Trauma
under Inhalation Anesthesia and under Normal Conditions


I looked into this problem from many viewpoints and there seemed
to be no solution until it occurred to me to seek the explanation
in certain of the postulates which make up the doctrine of evolution.
I realize fully the difficulty and the danger in attempting
to reach the generalization which I shall make later and in
the hypothesis I shall propose, for there is, of course, no direct
final proof of the truth of even the doctrine of evolution.
It is idle to consider any experimental research into the cause
of phenomena that have developed by natural selection during
millions of years.  Nature herself has made the experiments on
a world-wide scale and the data are before us for interpretation.
Darwin could do no more than to collect all available facts and then
to frame the hypothesis by which the facts were best harmonized.
Sherrington, that masterly physiologist, in his volume entitled
"The Integrative Action of the Nervous System," shows clearly how
the central nervous system was built up in the process of evolution.
Sherrington has made free use of Darwin's doctrine in explaining
physiologic functions, just as anatomists have extensively
utilized it in the explanation of the genesis of anatomic forms.
I shall assume, therefore, that the discharge of nervous energy is
accomplished by the application of the laws of inheritance and association,
and I conclude that this hypothesis will explain many clinical phenomena.
I shall now present such evidence in favor of this hypothesis as time
and my limitations will admit, after which I shall point out certain
clinical facts that may be explained by this hypothesis.

According to the doctrine of evolution, every function owes
its origin to natural selection in the struggle for existence.
In the lower and simpler forms of animal life, indeed, in our
human progenitors as well, existence depended principally upon
the success with which three great purposes were achieved:
(1) Self-defense against or escape from enemies; (2) the acquisition
of food; and (3) procreation; and these were virtually the only purposes
for which nervous energy was discharged.  In its last analysis,
in a biologic sense, this statement holds true of man today.
Disregarding for the present the expenditure of energy for procuring
food and for procreation, let us consider the discharge of energy
for self-preservation. The mechanisms for self-defense which we
now possess were developed in the course of vast periods of time
through innumerable intermediary stages from those possessed by
the lowest forms of life.  One would suppose, therefore, that we must
now be in possession of mechanisms which still discharge energy on
adequate stimulation, but which are not suited to our present needs.
We shall point out some examples of such unnecessary mechanisms.
As Sherrington has stated, our skin, in which are implanted many
receptors for receiving specific stimuli which are transmitted
to the brain, is interposed between ourselves and the environment
in which we are immersed.  When these stimuli reach the brain,
there is a specific response, principally in the form of
muscular action.  Now, each receptor can be adequately stimulated
only by the particular factor or factors in the environment
which created the necessity for the existence of that receptor.
Thus there have arisen receptors for touch, for temperature,
for pain, etc.  The receptors for pain have been designated _nociceptors_
(nocuous or harmful) by Sherrington.

On the basis of natural selection, nociceptors could have developed
in only those regions of the body which have been exposed to injury
during long periods of time.  On this ground the finger, because it
is exposed, should have many nociceptors, while the brain, though the
most important organ of the body, should have no nociceptors because,
during a vast period of time, it has been protected by a skull.
Realizing that this point is a crucial one, Dr. Sloan and I made a series
of careful experiments.  The cerebral hemispheres of dogs were exposed
by removing the skull and dura under ether and local anesthesia.
Then various portions of the hemispheres were slowly but
completely destroyed by rubbing them with pieces of gauze.
In some instances a hemisphere was destroyed by burning.
In no case was there more than a slight response of the centers governing
circulation and respiration, and no morphologic change was noted
in an histologic study of the brain-cells of the uninjured hemisphere.
The experiment was as completely negative as were the experiments
on the "spinal dog."  Clinically I have confirmed these experimental
findings when I have explored the brains of conscious patients
with a probe to determine the presence of brain tumors.
Such explorations elicited neither pain nor any evidence of altered
physiologic functions.  The brain, therefore, contains no mechanism--
no nociceptors--the direct stimulation of which can cause
a discharge of nervous energy in a self-defensive action.
That is to say, direct injury of the brain can cause no purposeful
nerve-muscular action, while direct injury of the finger does cause
purposeful nerve-muscular action.  In like manner, the deeper portions
of the spinal region have been sheltered from trauma and they, too,
show but little power of causing a discharge of nervous energy
on receiving trauma.  The various tissues and organs of the body
are differently endowed with injury receptors--the nociceptors
of Sherrington.  The abdomen and chest when traumatized stand first
in their facility for causing the discharge of nervous energy, _i.
e_., THEY STAND FIRST IN SHOCK PRODUCTION.  Then follow the extremities,
the neck, and the back.  It is an interesting fact also that different
types of trauma elicit different responses as far as the consequent
discharge of energy is concerned.

Because it is such a commonplace observation, one scarcely realizes
the importance of the fact that clean-cut wounds inflicted
by a razor-like knife cause the least reaction, while a tearing,
crushing trauma causes the greatest response.  It is a suggestive fact
that the greatest shock is produced by any technic which imitates
the methods of attack and of slaughter used by the carnivora.
_*In the course of evolution, injuries thus produced may well have
been the predominating type of traumata to which our progenitors
were subjected_.  In one particular respect there is an analogy between
the response to trauma of some parts of the body of the individuals
of a species susceptible to shock and the response to trauma of the
individuals in certain other great divisions of the animal kingdom.
Natural selection has protected the crustaceans against their
enemies by protective armor, _e.  g_., the turtle and the armadillo;
to the birds, it has given sharp eyes and wings, as, for instance,
the wild goose to another species--the skunk--it has given a noisome odor
for its protection.  The turtle, protected by its armor against trauma,
is in a very similar position to that of the sheltered brain
of man and, like the brain, the turtle does not respond to trauma
by an especially active self-protective nerve-muscular response,
but merely withdraws its head and legs within the armored protection.
It is proverbially difficult to exhaust or to kill this animal by trauma.
The brain and other phylogenetically sheltered parts likewise give no
exhausting self-protective nerve-muscular response to trauma.  The skunk
is quite effectively protected from violence by its peculiar odor.
This is indicated not only by the protective value of the odor itself,
but also by the fact that the skunk has no efficient nerve-muscular
mechanism for escape or defense; it can neither run fast nor can it
climb a tree.  Moreover, in encounters it shows no fear and backs
rather than runs.  The armadillo rolls itself into a ball for defense.
On these premises we should conclude that the turtle,
the armadillo, and the skunk have fewer nociceptors than has
a dog or man, and that they would show less response to trauma.
In two carefully conducted experiments on skunks and two on armadillos
(an insufficient number) the energy discharged in response to severe
and protracted trauma of the abdominal viscera was very much less than
in similar experiments on dogs, opossums, pigs, sheep, and rabbits.
It was indeed relatively difficult to exhaust the skunks and armadillos
by trauma.  These experiments are too few to be conclusive,
but they are of some value and furnish an excellent lead.
It seems more than a coincidence that proneness to fear,
distribution of nociceptors, and susceptibility to shock go
hand-in-hand in these comparative observations (Figs. 6, 7, and 8).

The discharge of energy caused by an adequate mechanical stimulation
of the nociceptors is best explained in accordance with the law
of phylogenetic association.  That is, injuries awaken those reflex
actions which by natural selection have been developed for the purpose
of self-protection. Adequate stimulation of the nociceptors for pain
is not the only means by which a discharge of nervous energy is caused.
Nervous energy may be discharged also by adequate stimulation
of the various ticklish regions of the body; the entire skin
surface of the body contains delicate ticklish receptors.
These receptors are closely related to the nociceptors for pain,
and their adequate stimulation by an insect-like touch
causes a discharge of energy,--a nerve-muscular reaction,--
resembling that developed for the purpose of brushing off insects.
This reflex is similar to the scratch reflex in the dog.
The discharge of energy is almost wholly independent of the will
and is a self-protective action in the same sense as is the response
to pain stimuli.  The ear in man and in animals is acutely ticklish,
the adequate stimulus being any foreign body, especially a buzzing,
insect-like contact.  The discharge of nervous energy in horses
and in cattle on adequate stimulation of the ticklish receptors
of the ear is so extraordinary that in the course of evolution it
must have been of great importance to the safety of the animal.
A similar ticklish zone guards the nasal chambers, the discharge of energy
here taking a form which effectively dislodges the foreign body.
The larynx is exquisitely ticklish, and, in response to any adequate
stimulus, energy is discharged in the production of a vigorous cough.
The mouth and pharynx have active receptors which cause the rejection
of noxious substances.  The conjunctival reflex, though not
classed as ticklish, is a most efficient self-protective reflex.
I assume that there is no doubt as to the relation between
the adequate stimuli and the nerve-muscular response of the various
ticklish receptors of the surface of the skin, of the ear,
the nose, the eye, and the larynx.  These mechanisms were developed
by natural selection as protective measures against the intrusion
of insects and foreign bodies into regions of great importance.
The discharge of energy in these instances is in accordance
with the laws of inheritance and association.  The other ticklish
points which are capable of discharging vast amounts of energy
are the lateral chest-wall, the abdomen, the loins, the neck,
and the soles of the feet.  The type of adequate stimuli of the soles
of the feet, the distribution of the ticklish points upon them,
and the associated response, leave no doubt that these ticklish points
were long ago established as a means of protection from injury.
Under present conditions they are of little value to man.

The adequate stimulus for the ticklish points of the ribs,
the loins, the abdomen, and the neck is deep isolated pressure,
probably the most adequate being pressure by a tooth-shaped body.
The response to tickling in these regions is actively and obviously
self-defensive. The horse discharges energy in the form of a kick;
the dog wriggles and makes a counter-bite; the man makes efforts
at defense and escape.

There is strong evidence that the deep ticklish points of the body
were developed through vast periods of fighting with teeth and claws
(Fig. 9). Even puppies at play bite each other in their ticklish
points and thus give a recapitulation of their ancestral battles
and of the real battles to come (Fig. 10). The mere fact that animals
fight effectively in the dark and always according to the habit
of their species supports the belief that the fighting of animals
is not an intellectual but a reflex process.  There are no rules
which govern the conduct of a fight between animals.  The events
follow each other with such kaleidoscopic rapidity that the process
is but a series of automatic stimulations and physiologic reactions.
Whatever their significance, therefore, it is certain that man did
not come either accidentally or without purpose into possession
of the deep ticklish regions of his chest and abdomen.
Should any one doubt the vast power that adequate stimulation
of these regions possesses in causing the discharge of energy,
let him be bound hand and foot and vigorously tickled for an hour.
What would happen?  He would be as completely exhausted as though he had
experienced a major surgical operation or had run a Marathon race.

A close analogy to the reflex process in the fighting of animals
is shown in the role played by the sexual receptors in conjugation.
Adequate stimulation of either of these two distinct groups
of receptors, the sexual and the noci, causes specific behavior--
the one toward embrace, the other toward repulsion.  Again, one of
the most peremptory causes of the discharge of energy is that due
to an attempt to obstruct forcibly the mouth and the nose so that
asphyxia is threatened.  Under such conditions neither friend
nor foe is trusted, and a desperate struggle for air ensues.
It will be readily granted that the reactions to prevent suffocation
were established for the purpose of self-preservation, but the discharge
of nerve-muscular energy to this particular end is no more specific
and no more shows adaptive qualities than do the preceding examples.
Even the proposal to bind one down hand and foot excites resentment,
a feeling originally suggested by the need for self-preservation.
No patient views with equanimity the application of shackles
as a preparation for anesthesia.

We have now considered some of the causes of those discharges of nervous
energy which result from various types of harmful physical contact,
and have referred to the analogous, though antithetical,
response to the stimulation of the sexual receptors.
The response to the adequate stimuli of each of the several receptors
is a discharge of nerve-muscular energy of a specific type; that is,
there is one type of response for the ear, one for the larynx,
one for the pharynx, another for the nose, another for the eye,
another for the deep ticklish points of the chest and the abdomen,
quite another for the delicate tickling of the skin, and still
another type of response to sexual stimuli.

According to Sherrington, a given receptor has a low threshold
for only one, its own specific stimulus, and a high threshold
for all others; that is, the doors that guard the nerve-paths
to the brain are opened only when the proper password is received.
According to Sherrington's law, the individual as a whole responds
to but one stimulus at a time, that is, only one stimulus
occupies the nerve-paths which carry the impulses as a result
of which acts are performed, _i.  e_., the final common path.
As soon as a stronger stimulus reaches the brain it dispossesses
whatever other stimulus is then occupying the final common path--
the path of action.  The various receptors have a definite order
of precedence over each other (Sherrington). For example, the impulse
from the delicate ticklish points of the skin, whose adequate
stimulus is an insect-like contact, could not successfully compete
for the final common path with the stimulus of a nociceptor.
The stimulus of a fly on the nose would be at once superseded by
the crushing of a finger.  In quick succession do the various receptors
(Sherrington) occupy the final common path, but each stimulus is for
the time the sole possessor, hence the nervous system is integrated
(connected) to act as a whole.  Each individual at every moment
of life has a limited amount of dischargeable nervous energy.
This energy is at the disposal of any stimulus that obtains possession
of the final common path, and results in the performance of an act.
Each discharge of energy is subtracted from the sum total of stored
energy and, whether the subtractions are made by the excitation
of nociceptors by trauma, by tickling, by fighting, by fear,
by flight, or by the excitation of sexual receptors, by any
of these singly or in combination with others, the sum total of
the expenditure of energy, if large enough, produces exhaustion.
Apparently there is no distinction between that state of exhaustion
which is due to the discharge of nervous energy in response
to trauma and that due to other causes.  The manner of the
discharge of energy is specific for each type of stimulation.
On this conception, traumatic shock takes its place as a natural
phenomenon and is divested of its mask of mystery.


The Discharge of Energy through Stimulation of the Distance Receptors,
or through Representation of Injury (Psychic)


We will now turn from the discussion of the discharge of nervous energy by
mechanical stimuli to the discharge of energy through mental perception.
_Phylogenetic_ association may result from stimulation of the distance
receptors through sight, hearing, smell, or by a representation
of physical experiences, as well as from physical contact.
The effect upon the organism of the representation of injury
or of the perception of danger through the distance receptors is
designated FEAR.  Fear is as widely distributed in nature as is its cause,
that is, fear is as widely distributed as injury.  Animals under
the stimulus of fear, according to W. T. Hornaday, not only may exhibit
preternatural strength, but also may show strategy of the highest order,
a strategy not seen under the influence of a lesser stimulus.
In some animals fear is so intense that it defeats escape; this is
especially true in the case of birds in the presence of snakes.
The power of flight has endowed the bird with an easy means of escape
from snakes, especially when the encounter is in the tops of trees.
Here the snake must move cautiously, else he will lose his equilibrium;
his method of attack is by stealth.  When the snake has stalked
its prey, the bird is often so overcome by fear that it cannot fly
and so becomes an easy victim (Fig. 11). The phenomena of fear
are described by Darwin as follows:

"Fear is often preceded by astonishment, and is so near akin to it that
both lead to the senses of sight and hearing being instantly aroused.
In both cases the eyes and mouth are widely opened and the
eyebrows raised.  The frightened man at first stands like a statue,
motionless and breathless, or crouches down as if instinctively
to escape observation.  The heart beats quickly and violently,
so that it palpitates or knocks against the ribs.  * * * That the skin
is much affected under the sense of great fear we see in the marvelous
and inexplicable manner in which perspiration immediately exudes from it.
This exudation is all the more remarkable as the surface is then cold,
and hence the term, `a cold sweat'; whereas the sudorific glands
are properly excited into action when the surface is heated.
The hairs also on the skin stand erect, and the superficial
muscles shiver.  In connection with the disturbed action of the heart,
the breathing is hurried.  The salivary glands act imperfectly;
the mouth becomes dry, and is often opened and shut.  I have also
noticed that under slight fear there is a strong tendency to yawn.
One of the best-marked symptoms is the trembling of all the
muscles of the body; and this is often first seen in the lips.
From this cause, and from the dryness of the mouth, the voice
becomes husky and indistinct, or may altogether fail.
* * * As fear increases into agony of terror, we behold, as under
all violent emotions, diversified results.  The heart beats wildly,
or may fail to act and faintness ensues; there is death-like pallor;
the breathing is labored; the wings of the nostrils are widely dilated;
`there is a gasping and convulsive motion of the lips, a tremor
on the hollow cheek, a gulping and catching of the throat';
the uncovered and protruding eyeballs are fixed on the object of terror;
or they may roll restlessly from side to side.  * * * The pupils
are said to be enormously dilated.  All the muscles of the body
may become rigid, or may be thrown into convulsive movements.
The hands are alternately clenched and opened, often with a
twitching movement.  The arms may be protruded, as if to avert
some dreadful danger, or may be thrown wildly over the head.
* * * In other cases there is a sudden and uncontrollable tendency
to headlong flight; and so strong is this that the boldest soldiers
may be seized with a sudden panic.  As fear rises to an extreme pitch,
the dreadful scream of terror is heard.  Great beads of sweat
stand on the skin.  All the muscles of the body are relaxed.
Utter prostration soon follows, and the mental powers fail.
The intestines are affected.  The sphincter muscles cease
to act and no longer retain the contents of the body.
* * * Men, during numberless generations, have endeavored
to escape from their enemies or danger by headlong flight,
or by violently struggling with them; and such great exertions
will have caused the heart to beat rapidly, the breathing to
be hurried, the chest to heave, and the nostrils to be dilated.
As these exertions have often been prolonged to the last extremity,
the final result will have been utter prostration, pallor, perspiration,
trembling of all the muscles, or their complete relaxation.
And now, whenever the emotion of fear is strongly felt, though it
may not lead to any exertion, the same results tend to reappear,
through the force of inheritance and association"[*] (Fig. 12).


[*] Darwin:  Expression of the Emotions in Man and Animals.


In an experimental research, we found evidence that the physiologic
phenomena of fear have a physical basis.  This evidence is found
in the morphologic alterations in the brain-cells, which are similar
to those observed in certain stages of surgical shock and in fatigue
from muscular exertion (Figs. 2, 4, 5, and 13). For the present,
we shall assume that fear is a REPRESENTATION of trauma.
Because fear was created by trauma, fear causes a discharge of the energy
of the nervous system by the law of phylogenetic association.
The almost universal fear of snakes, of blood, and of death
and dead bodies may have such a phylogenetic origin.
It was previously stated that under the stimulus of fear animals
show preternatural strength.  An analysis of the phenomena of fear
shows that, as far as can be determined, all the functions of the body
requiring the expenditure of energy, and which are of no direct
assistance in the effort toward self-preservation, are suspended.
In the voluntary expenditure of muscular energy, as in the chase,
the suspension of other functions is by no means so complete.
Fear and trauma may drain to the last dreg the dischargeable
nervous energy, and, therefore, the greatest possible exhaustion
may be produced by fear and trauma.


Summation

In the discharge of energy, summation plays an important role.
Summation is attained by the repetition of stimuli at such a rate
that each succeeding stimulus is applied before the nerve-cells
have returned to the resting stage from the preceding stimulus.
If drops of water fall upon the skin from a sufficient height to cause
the slightest unpleasant sensation, and at such a rate that before
the effect of the stimulus of one drop has passed another drop
falls in precisely the same spot, there will be felt a gradually
increasing painful sensation which finally becomes unbearable.
This is summation of stimuli.  When, for a long time, a patient
requires frequent painful wound dressings, there is a gradual
increase in the acuteness of the pain of the receptors.
This is caused by summation.  In a larger sense, the entire behavior
of the individual gives considerable evidence of summation, _e.
g_., in the training of athletes, the rhythmic discharge of muscular
energy at such intervals that the resting stage is not reached
before a new exercise is given results in a gradual ascent
in efficiency until the maximum is reached.  This is summation,
and summation plays a large role in the development of both normal
and pathologic phenomena.

We have now pointed out the manner in which at least
a part of the nervous energy of man may be discharged.
The integrative action of the nervous system and the discharge
of nervous energy by phylogenetic association may be illustrated
by their analogy to the action of an electric automobile.
The electric automobile is composed of four principal parts:
The motor and the wheels (the muscular system and the skeleton);
the cells of the battery containing stored electricity
(brain-cells, nervous energy); the controller, which is connected
with the cells by wiring (the receptors and the nerve-fibers);
and an accelerator for increasing the electric discharge
(thyroid gland?). The machine is so constructed that it acts
as a whole for the accomplishment of a single purpose.
When the controller is adjusted for going ahead (adequate stimulus
of a receptor), then the conducting paths (the final common path)
for the accomplishment of that purpose are all open to the flow of
the current from the battery, and the vehicle is integrated to go ahead.
It spends its energy to that end and is closed to all other impulses.
When the controller is set for reverse, by this adequate stimulus
the machine is integrated to back, and the battery is closed to all
other impulses.  Whether integrated for going forward or backward,
if the battery be discharged at a proper rate until exhausted,
the cells, though possessing no more power (fatigue), have sustained
no further impairment of their elements than that of normal wear
and tear.  Furthermore, they may be restored to normal activity
by recharging (rest). If the vehicle be placed against a stone wall,
and the controller be placed at high-speed (trauma and fear),
and if the accelerator be used as well (thyroid secretion?), though
the machine will not move, not only will the battery soon be exhausted,
but the battery elements themselves will be seriously damaged
(exhaustion--surgical shock).

We have now presented some evidence that nervous energy is
discharged by the adequate stimulation of one or more of the various
receptors that have been developed in the course of evolution.
In response to an adequate stimulus, the nervous system is
integrated for a specific purpose by the stimulated receptor,
and but one stimulus at a time has possession of the final common path--
the nerve mechanisms for action.  The most numerous receptors
are those for harmful contact; these are the nociceptors.
The effect of the adequate stimulus of a nociceptor is like that of
pressing an electric button that sets great machinery in motion.

With this conception, the human body may be likened to a
musical instrument--an organ--the keyboard of which is composed
of the various receptors, upon which environment plays the many
tunes of life; and written within ourselves in symbolic language
is the history of our evolution.  The skin may be the "Rosetta Stone"
which furnishes the key.


Anoci-association


By the law of phylogenetic association, we are now prepared
to make a practical application of the principles of the discharge
of nervous energy.  In the case of a surgical operation, if fear
be excluded and if the nerve-paths between the field of operation
and the brain be blocked with cocain,[*] no discharge of energy will be
caused by the operation; hence no shock, no exhaustion, can result.
Under such conditions the nervous system is protected against
noci-association, resulting from noci-perception or from an adequate
stimulation of nociceptors.  The state of the patient in whom all
noci-associations are excluded can be described only by coining
a new word.  That word is "anoci-association" (Fig. 14).


[*] See footnote, page 4.@@@


The difference between anesthesia and anoci-association is that,
although _inhalation anesthesia_ confers the beneficent loss of
consciousness and freedom from pain, it does not prevent the nerve
impulses from reaching and influencing the brain, and therefore does
not prevent surgical shock nor the train of later nervous impairments
so well described by Mumford.  _Anoci-association_ excludes fear,
pain, shock, and postoperative neuroses.  _Anoci-association_ is
accomplished by combining the special management of patients
(applied psychology), morphin, inhalation anesthesia,
and local anesthesia.

We have now presented in summary much of the mass of experimental
and clinical evidence we have accumulated in support of our
principal theme, which is that the discharge of nervous energy is
accomplished in accordance with the law of phylogenetic association.
If this point seems to have been emphasized unduly, it is because
we expect to rear upon this foundation a clinical structure.
How does this hypothesis apply to surgical operations?


Prevention of Shock by the Application of the Principle of
Anoci-association



Upon this hypothesis a new principle in operative surgery is founded, _i.
e_., operation during the state of _anoci-association_. Assuming that
no unfavorable effect is produced by the anesthetic and that there is
no hemorrhage, the cells of the brain cannot be exhausted in the course
of a surgical operation except by fear or by trauma, or by both.
Fear may be excluded by narcotics and special management until
the patient is rendered unconscious by inhalation anesthesia.
Then if, in addition to inhalation anesthesia, the nerve-paths
between the brain and the field of operation are blocked with
cocain,[*] the patient will be placed in the beneficent state of
_anoci-association_, and at the completion of the operation will be
as free from shock as at the beginning.  In so-called "fair risks"
such precautions may not be necessary, but in cases handicapped
by infections, by anemia, by previous shock, and by Graves'
disease, etc., anoci-association may become vitally important.


[*] See footnote, page 4.@@@


Graves' Disease


By applying the principle of the discharge of nervous energy by
phylogenetic association, and by making the additional hypothesis
that in the discharge of nervous energy the thyroid gland is stimulated
through the nervous system, we can explain many of the phenomena
of Graves' disease and may possibly discover some of the factors
which explain both its genesis and its cure.

In the wild state of animal life in which only the fittest
survive in the struggle for existence, every point of advantage
has its value.  An animal engaged in battle or in a desperate
effort to escape will be able to give a better account of itself
if it have some means of accelerating the discharge of energy--
some influence like that of pouring oil upon the kindling fire.
There is evidence, though perhaps it is not conclusive,
that such an influence is exerted by the thyroid gland.
In myxedema, a condition characterized by a lack of thyroid secretion,
there is dulness of the reflexes and of the intellect, a lowered
muscular power, and generally a sluggish discharge of energy.
In Graves' disease there is an excessive production of thyroid secretion.
In this disease the reflexes are increased, the discharge of
energy is greatly facilitated, and metabolism is at a maximum.
The same phenomena occur also after the administration of thyroid
extract in large doses to normal subjects.  In the course of
sexual activities there is an increased action of the thyroid,
which is indicated by an increase in its size and vascularity.
That in fear and in injury the thyroid, in cases of Graves'
disease, is probably stimulated to increased activity is indicated
by the increased activity of the thyroid circulation, by an increase
in the size of the gland, by the histologic appearance of activity
in the nuclei of the cells, and by an increase of the toxic symptoms.
Finally, Asher has stated that electric stimulation of the nerve supply
of the thyroid causes an increased secretion.  The origin of many cases
of Graves' disease is closely associated with some of the causes
of the discharge of nervous energy, depressive influences especially,
such as nervous shocks, worry and nervous strain, disappointment in love,
business reverses, illness and death of relatives and friends.
The association of thyroid activity with procreation is well known,
hence the coincidence of a strain of overwork or of fear with
the sexual development of maturing girls is obviously favorable
to the incidence of Graves' disease.  The presence of a colloid goiter
is a suitable soil for the development of Graves' disease, and I
fully recognize also the evidence that infection or auto-intoxication
may be contributing factors and must be assigned their role.

I have never known a case of Graves' disease to be caused by success
or happiness alone, or by hard physical labor unattended by
psychic strain, or to be the result of energy voluntarily discharged.
Some cases seem to have had their origin in overdosage with thyroid
extract in too vigorous an attempt to cure a colloid goiter.
One of the most striking characteristics of Graves' disease is
the patient's loss of control and his increased susceptibility
to stimuli, especially to trauma and to fear and to the administration
of thyroid extract.  It has been shown that the various causes
of the discharge of nervous energy produce alterations in the nervous
system and probably in the thyroid gland.  This is especially
true of the fear stimulus, and has been clearly demonstrated
in the brains of rabbits which had been subjected to fear alone
(Fig. 13). Of special interest was the effect of daily fright.
In this case the brain-cells showed a distinct change, although the animal
had been subjected to no fear for twenty-four hours before it was killed
(Fig. 13 C. Now, a great distinction between man and the lower
animals is the greater control man has acquired over his actions.
This quality of control, having been phylogenetically most recently
acquired, is the most vulnerable to various NOCUOUS influences.
The result of a constant noci-integration may be a wearing-out
of the control cells of the brain.  In a typical case of Graves'
disease a marked morphologic change in the brain-cells has
been demonstrated (Fig. 15). As has been previously stated,
the origin of many cases of Graves' disease is associated
with some noci-influence. If this influence causes stimulation
of both the brain and the thyroid, its excessive action may cause
impairment of the brain and also hyperplasia of the thyroid.
As self-control is impaired, fear obtains an ascendency and,
_pari passu_, stimulates the thyroid still more actively (Fig. 16).
Finally, the fear of the disease itself becomes a noci-stimulus.
As the thyroid secretion causes an increase in the facility
with which nervous energy is discharged, a pathologic reciprocal
interaction is established between the brain and the thyroid.
The effect of the constantly recurring stimulus of the noci-influence
is heightened by summation.  This reciprocal goading may
continue until either the brain or the thyroid is destroyed.
If the original noci-stimulus is withdrawn before the fear of the
disease becomes too strong, and before too much injury to the brain
and the thyroid has been inflicted, a spontaneous cure may result.
Recovery may be greatly facilitated by complete therapeutic rest.
A cure implies the return of the brain-cells to their normal state,
with the reestablishment of the normal self-control and the
restoration of the thyroid to its normal state, when the impulses
of daily life will once more have possession of the final
common path and the noci-influence will be dispossessed.
The discovery of the real cause of a given case of Graves' disease is
frequently difficult because it may be of a painful personal nature.
Of extreme interest is the fact that, in the acute stage,
the patient may be unable to refer to the exciting cause without
exhibiting an exacerbation of the symptoms of the disease.
I presume no case should be regarded as cured until reference
can be made to its cause without an abnormal reaction.
It has been established that in Graves' disease injury to any part
of the body, even under inhalation anesthesia, causes an exacerbation
of the disease.  Fear alone may cause an acute exacerbation.
These acute exacerbations are frequently designated "hyperthyroidism"
and are the special hazard of operation.

In applying the principle of anoci-association in operations on
patients with Graves' disease there is scarcely a change in the pulse,
in the respiration, or in the nervous state at the close of the operation.
I know no remedy which can obviate the effect of the inflowing
stimuli from the wound after the cocain[*] has worn off.[t] It
is necessary, therefore,


Beats 70 80 90 100 110 120



Ether ******* ******** ******** ******** ********



N2O ******* ******** ******** ******** *



Anoci.  ******* ******** ******** ** not to venture too far
in serious cases.  Since the adoption of this new method
(anoci-association) my operative results have been so vastly improved
that I now rarely regard any case of Graves' disease as inoperable,
at least to the extent of contraindicating a double ligation (Fig. 17).


[*] See footnote, page 4.@@@

[t] In later papers and in "Anoci-association" (Crile and Lower)
methods of combating postoperative hyperthyroidism are fully discussed.


If we believe that, in accordance with the law of phylogenetic association,
a continuous stimulation of both the brain and the thyroid gland,
accelerated by summation, plays a role in the establishment
of the pathologic interaction seen in Graves' disease, then it
is but the next step to assume that if the nerve connection between
the brain and the thyroid be severed, or if the lobe be excised
and the patient reinforced by a sojourn in a sanatorium or in some
environment free from former noci-associations, he may be restored
to normal health, provided that the brain-cells, the heart,
or other essential organs have not suffered irreparable damage.
There are still many missing links in the solution of this problem,
and the foregoing hypotheses are not offered as final, although from
the viewpoint of the surgeon many of the phenomena of this
disease are explicable.


Sexual-Neurasthenia


The state of sexual neurasthenia is in many respects analogous
to that of Graves' disease.  In the sexual reflexes, summation leads
to a hyperexcitability by psychic and mechanical stimuli of a
specific type which is analogous to the hyperexcitability in Graves'
disease under trauma and fear; the explanation of both conditions
is based on the laws of the discharge of energy by phylogenetic
association and summation.  It would be interesting to observe
the effect of interrupting the nerve impulses from the field of
the sexual receptors by injections of alcohol, or by other agencies,
so as to exclude the associational stimuli until the nervous
mechanism has again become restored to its normal condition.
Interpretation of Some of the Phenomena of Certain Diseases of the
Abdomen in Accordance with the Hypothesis of Phylogenetic Association


The law of phylogenetic association seems to explain many
of the phenomena of certain lesions in the abdominal cavity.
The nociceptors in the abdomen, like nociceptors elsewhere, have been
established as a result of some kind of injury to which during
vast periods of time this region has been frequently exposed.
On this premise, we should at once conclude that there are no
nociceptors for heat within the abdomen because, during countless years,
the intra-abdominal region never came into contact with heat.
That this inference is correct is shown by the fact that the
application of a thermocautery to the intestines when completing
a colostomy in a conscious patient is absolutely painless.
One would conclude also that there are no touch receptors in the
abdominal viscera, and therefore no sense of touch in the peritoneum.
Just as the larynx, the ear, the nose, the sole of the foot,
and the skin have all developed the specific type of nociceptors
which are adapted for their specific protective purposes, and which,
when adequately stimulated, respond in a specific manner in accordance
with the law of phylogenetic association, so, the abdominal viscera
have developed equally specific nociceptors as a protection against
specific nocuous influences.  The principal harmful influences
to which the abdominal viscera have been exposed during vast periods
of time are deep tearing injuries by teeth and claws in the innumerable
struggles of our progenitors with each other and with their enemies
(Fig. 9); peritonitis caused by perforations of the intestinal
tract from ulcers, injuries, appendicitis, gall-stones, etc.;
and overdistention of the hollow viscera by various forms of obstruction.
Whatever may be the explanation, it is a fact that the type
of trauma which results from fighting corresponds closely with
that which causes the most shock in the experimental laboratory.
Division of the intestines with a sharp knife causes no pain,
but pulling on the mesentery elicits pain.  Ligating the stump
of the appendix causes sharp, cramp-like pains.  Sharp division
of the gall-bladder causes no pain, but distention, which is
the gall-bladder's most common pathologic state, produces pain.
Distention of the intestine causes great pain, but sharp cutting or burning
causes none.  In the abdominal viscera, as in the superficial parts,
nociceptors have presumably been developed by specific harmful
influences and each nociceptor is open to stimulation only by a
stimulus of the particular type that produced it.

As a result of the excitation of nociceptors, with which pain
is associated, the routine functions, such as peristalsis, secretion,
and absorption are dispossessed from the control of their respective
nervous mechanisms, just as they are inhibited by fear.  This hypothesis
explains the loss of weight, the lassitude, the indigestion,
the constipation, and the many alterations in the functions of the various
glands and organs of the digestive system in chronic appendicitis.
It readily explains also the extraordinary improvement in the digestive
functions and the general health which follows the removal
of an appendix which is so slightly altered physically that only
the clinical results could persuade one that this slight change could
be an adequate cause for such far-reaching and important symptoms.
This hypothesis explains certain gall-bladder phenomena likewise,--
indigestion, loss of weight, disturbed functions, etc.,--and it
may supply the explanation of the disturbance caused by an active
anal fissure, which is a potent noci-associator, and the consequent
disproportionate relief after the trivial operation for its cure.
Noci-association would well explain also the great functional disturbances
of the viscera which immediately follow abdominal operations.

Postoperative and traumatic neuroses are at once explained on
the ground of noci-association, the resulting strain from which,
upon the brain-cells, causes in them physical lesions.
If one were placed against a wall and were looking into the gun muzzles
of a squad of soldiers, and were told that there were nine chances
out of ten that he would not be killed outright when the volley
was fired, would it help him to be told that he must not be afraid?
Such an experience would be written indelibly on his brain.
This corresponds closely to the position in which some surgical patients
are placed.  In railway wrecks, we can readily understand the striking
difference between the after-effects in the passengers who were conscious
at the time of the accident and those who were asleep or drunk.
In the latter the noci-perceptors and receptors were not aroused,
hence their immunity to the nervous shock.  In the functional disturbances
of the pelvic organs, association and summation may play a large role.
On this hypothesis many cases of neurasthenia may well be explained.
From the behavior of the individual as a whole we may well conclude
that summation is but a scientific expression for "nagging."
Many other pathologic phenomena may be explained in a similar manner.
Thus we can understand the variations in the gastric analyses in a
timid patient alarmed over his condition and afraid of the hospital.
He is integrated by fear, and as fear takes precedence over all
other impulses, no organ functionates normally.  For the same reason,
one sees animals in captivity pine away under the dominance of fear.
The exposure of a sensitive brain to the naked possibility of death from
a surgical operation may be compared to uncovering a photographic plate
in the bright sunlight to inspect it before putting it in the camera.
This principle explains, too, the physical influence of the physician
or surgeon, who, by his PERSONALITY, inspires, like a Kocher,
absolute confidence in his patient.  The brain, through its power
of phylogenetic association, controls many processes that have wholly
escaped from the notice of the "practical man."  It is in accordance
with the law of association that a flower, a word, a touch, a cool breeze,
or even the thought of a fishing rod or of a gun, is helpful.
On the contrary, all suggestions of despair or misfortune--
a corrugated brow, the gloomy silence of despair, or a doubtful word--
are equally depressing.  In like manner, one could add many
illustrations of the symbolism that governs our daily lives.
Thus we see that through the laws of inheritance and noci-association,
we are able to read a new meaning into the clinical phenomena
of various diseases.


Observations on Patients whose Associational Centers are Dulled,
and on Diseases and Injuries of Regions not Endowed with Nociceptors


Reversing the order of our reasoning, let us now glance at the patient
who is unconscious and who, therefore, has lost much of the power
of association.  His mouth is usually dry, the digestive processes
are at a low ebb, the aroma of food causes no secretion of saliva,
tickling the nose causes no sneezing; he catches no cold.
The laryngeal reflex is lost and food may be quietly inhaled;
the entire process of metabolism is low.  The contrast between a man
whose associational centers are keen and a man in whom these centers
are dulled or lost is the contrast between life and death.

In accordance with the law of adaptation through natural selection,
phylogeny, and association, one would expect no pain in abscess
of the brain, in abscess of the liver, in pylephlebitis,
in infection of the hepatic vessels, in endocarditis.
This law explains why there are no nociceptors for cancer,
while there are active nociceptors for the acute infections.
It is because nature has no helpful response to offer against cancer,
while in certain of the acute pyogenic infections the nociceptors
force the beneficent physiologic rest.

Could we dispossess ourselves of the shackles of psychology,
forget its confusing nomenclature, and view the human brain,
as Sherrington has said, "as the organ of, and for the adaptation
of nervous reaction," many clinical phenomena would appear in
a clearer light.


Natural Selection and Chemical Noci-association in the Infections


Thus far we have considered the behavior of the individual as a whole
in his response to a certain type of noci-influences. We have been voicing
our argument in terms of physical escape from GROSS physical dangers,
or of grappling with GROSS NERVE-MUSCULAR enemies of the same or of
other species.  To explain these phenomena we have invoked the aid
of the laws of natural selection and phylogenetic association.
If our conclusions be correct, then it should follow that in the same
laws we may find the explanation of immunity, which, of course,
means a defensive response to our MICROSCOPIC enemies.  There should
be no more difficulty in evolving an efficient army of phagocytes
by natural selection, or in developing specific chemical reactions
against _*microscopic enemies_, than there was in evolving the various
nociceptors for our nerve-muscular defense against our _*gross enemies_.
That immunity is a chemical reaction is no argument against
the application of the law of natural selection or of association.
What essential difference is there between the chemical defense of
the skunk against its NERVE-MUSCULAR enemies and its chemical defense
(immunity) against its MICROSCOPIC ENEMIES?

The administration of vaccines becomes the adequate stimulus which
awakens phylogenetic association of a chemical nature as a result
of which immune bodies are produced.

In discussing this subject I will raise only the question whether
or not the specific character of the inaugural symptoms of some
infectious diseases may be due to phylogenetic association.
These inaugural symptoms are measurably a recapitulation of the leading
phenomena of the disease in its completed clinical picture.
Thus, the furious initiative symptoms of pneumonia, of peritonitis,
or erysipelas, of the exanthemata, are exaggerations of phenomena
which are analogous to the phenomena accompanying physical injury
and fear of physical violence.  Just as the acute phenomena of fear,
or those which accompany the adequate stimulation of nociceptors,
are recapitulations of phylogenetic struggles, so may the inaugural
symptoms of an infection be a similar phylogenetic recapitulation
of the course of the disease.  A certain amount of negative
evidence is supplied by a comparison of the response to a dose
of toxins with the response to a dose of a standard drug.
No drug in therapeutic dosage except the iodin compounds causes
a febrile response; no drug causes a chill; on the other hand,
all specific toxins cause febrile responses and many cause chills.
If a species of animal had been poisoned by a drug during vast periods
of time, and if natural selection had successfully established
a self-defensive response, then the administration of that drug would
cause a noci-association (chemical), and a specific reaction analogous
to that following the administration of Coley's toxins might be expected.
Bacterial noci-association probably operates through the same
law as that through which physical noci-association operates.
Natural selection is impartial, however.  It must be supposed that it
acts impartially upon the microscopic invader and upon the host.
On this ground one must infer that, in accordance with the same law
of natural selection, the bacteria of acute infections have met
by natural selection each advance in the struggle of the host
for immunity.  Hence the fast and furious struggle between man
and his microscopic enemies merely indicates to what extent natural
selection has developed the ATTACK and the DEFENSE respectively.
This struggle is analogous to the quick and decisive battles
of the carnivora when fighting among themselves or when contending
against their ancient enemies.  But when phylogenetically strange
animals meet each other, they do not understand how to conduct a fight:
natural selection has not had the opportunity of teaching them.
The acute infections have the characteristics of being ancient enemies.
On this hypothesis one can understand the high mortality of measles
when it is introduced into a new country.  By natural selection,
measles has become a powerful enemy of the human race, and a race
to which this infection is newly introduced has not had the advantage
of building up a defense against it by the law of natural selection.
May not the phenomena of anaphylaxis be studied on associational lines?
Then, too, there may be chemical noci-associations with enemies
now extinct, which, like the ticklish points, may still be active
on adequate stimulation.  This brief reference to the possible
relation of the phenomena of the acute infections to the laws
of natural selection and of specific chemical noci-association has
been made as a suggestion.  Since the doctrine of evolution explains
all or nothing, I have included many phenomena to see how reasonable
or unreasonable such an explanation might be.


Recapitulation


The following are the principal points presented:  In operations
under inhalation anesthesia the nerve impulses from the trauma
reach every part of the brain--the cerebrum that is apparently
anesthetized as well as the medulla that is known to remain awake--
the proof being the PHYSIOLOGIC exhaustion of and the PATHOLOGIC
change in the nerve-cells. Under ether anesthesia the damage
to the nerve-cells is at least four times greater than under
nitrous oxid.  Inhalation anesthesia is, therefore, but a veneer--
a mask that "covers the deep suffering of the patient."  The cause
of the exhaustion of the brain is the discharge of nervous energy
in a futile effort to energize the paralyzed muscles in an attempt
to escape from the injury just as if no anesthetic had been given.
The exhaustion is, therefore, of the same nature as that from overexertion,
but if the nerve-paths connecting the field of operation
and the brain be blocked, then there is no discharge of nervous
energy from the trauma, and consequently there is no exhaustion,
however severe or prolonged the operation may be.

Fear is a factor in many injuries and operations.  The phenomena
of fear probably are exhibited only by animals whose natural defense
is nerve-muscular. The skunk, the porcupine, the turtle, have little
or no fear.  Fear is born of the innumerable injuries which have
been inflicted in the course of evolution.  Fear, like trauma,
may cause physiologic exhaustion of and morphologic changes
in the brain-cells. The representation of injury, which is fear,
being elicited by phylogenetic association, may be prevented
by the exclusion of the noci-association or by the administration
of drugs like morphin and scopolamin, which so impair the associational
function of the brain-cells that immunity to fear is established.
Animals whose natural defense is in muscular exertion, among which is man,
may have their dischargeable nervous energy exhausted by fear alone,
or by trauma alone, but most effectively by the combination of both.
What is the mechanism of this discharge of energy?  It is the adequate
stimulation of the nociceptors and the physiologic response for the purpose
of self-preservation. According to Sherrington, the nervous system
responds in action as a whole and to but one stimulus at a time.
The integration of the individual as a whole occurs not alone in injury
and fear, but also, though not so markedly, as a result of other
phylogenetic associations, such as those of the chase and procreation.
When adequate stimuli are repeated with such rapidity that the new
stimulus is received before the effect of the previous one has
worn off, a higher maximum effect is produced than is possible
under a single stimulus, however powerful.

Sexual receptors are implanted in the body by natural selection,
and the adequate stimuli excite the nerve-muscular reactions
of conjugation in a manner analogous to the action of the adequate
stimuli of the nociceptors.  The specific response of either
the sexual receptors or the nociceptors is at the expense
of the total amount of nervous energy available at the moment.
Likewise in daily labor, which, in the language of evolution,
is the chase, nervous energy is expended.  Under the dominance
of fear or injury, however, the integration is most nearly
absolute and probably every expenditure of nervous energy which is
not required for efforts toward self-preservation is arrested;
hence fear and injury drain the cup of energy to the dregs.
This is the potential difference between fear and desire,
between injury and conjugation.

What is the practical application of this?  In operative surgery
there is introduced a new principle, which removes from surgery much
of the immediate risk from its trauma by establishing ANOCI-ASSOCIATION;
it places certain of the phenomena of fear on a physical basis;
it explains to us the physical basis for the impairment of the entire
individual under worry or misfortune; it makes evident the physical
results of the daily noci-associations experienced by the individual
as a social unit.  On the other hand, it explains the power
of therapeutic suggestion and of other influences which serve
for the time to change the noci-integration; it shows the physical
basis for the difference between hope and despair; it explains
some of the phenomena of Graves' disease, of sexual neurasthenia,
possibly of hay-fever and of the common cold.  The principle is probably
equally applicable to the acute infections, in each of which chemical
noci-association gives rise to many of the phenomena of the disease
and it explains their cure by natural immunity and by vaccines.
This hypothesis should teach us to view our patients as a whole;
and especially should it teach the surgeon gentleness.  It should
teach us that there is something more in surgery than mechanics,
and something more in medicine than physical diagnosis and drugs.


Conclusion


The brain-cells have existed for eons and, amid the vicissitudes
of change, they have persisted with perhaps less alteration than has
the crust of the earth.  Whether in man or in the lower animals,
they are related to and obey the same general biologic laws,
thus being bound to the entire past and performing their function
in accordance with the law of phylogenetic association.

For so long a time have we directed our attention to tumors,
infections, and injuries that we have not sufficiently considered
the vital force itself.  We have viewed each anatomic and pathologic
part as an entity and man as an isolated phenomenon in nature.
May we not find in the laws of adaptation under natural selection,
and of phylogenetic association, the master key that will disclose
to us the explanation of many pathologic phenomena as they have
already explained many normal phenomena?

And may medicine not correlate the pathologic phenomena of the sick
man with the forces of evolution, as the naturalists have correlated
the phenomena of the sound man, and thus may not disease, as well
as health, be given its evolutionary setting?



PHYLOGENETIC ASSOCIATION IN RELATION TO THE EMOTIONS[*]


[*] Address before the American Philosophical Society, Philadelphia,
April 22, 1911.


The surgeon is familiar with the manifestations of every variety
of the human emotions in the various stations of life, from infancy
to senility, in health and in disease.  Not only does he come
into intimate contact with the emotions displayed by the victims
of disease and of accidents, but he also observes those manifested
by the relatives and friends of the families of his patients.
Moreover, he is unhappily forced to notice the emotional effect
upon himself when he is waging an unequal battle against death--
the strain and worry at a crisis, when a life is in the balance
and a single false move may be fatal, is an experience known only
to the operating surgeon.

For the data for this paper, therefore, in which I shall for the most
part limit my discussion to the strongest of all emotions--FEAR--I have
drawn largely from my personal experience as a surgeon, as well
as from an experimental research in which I have had the valuable
assistance of my associates, Dr. H. G. Sloan, Dr. J. B. Austin,
and Dr. M. L. Menten.

I believe it can be shown that it is possible to elicit the emotion
of fear only in those animals that utilize a motor mechanism
in defense against danger or in escape from it.  For example,
the defense of the skunk is a diabolic odor which repels its enemies;
the skunk has no adequate equipment for defense or escape by
muscular exertion, and the skunk therefore shows little or no fear.
Again, certain species of snakes are protected by venom;
they possess no other means of defense nor have they adequate
motor mechanisms for escape and they show no fear.  Because of
their strength other animals, such as the lion, the grizzly bear,
and the elephant, show but little fear (Fig. 6). Animals which have
an armored protection, such as the turtle, show little fear.
It is, therefore, obvious that fear is not universal and that the
emotion of fear is felt only by those animals whose self-preservation
is dependent upon an uncertain adequacy of their power of muscular
exertion either for defense or for flight (Fig. 7).

What are the principal phenomena of fear?  They are palpitation
of the heart, acceleration of the rate and alteration of the rhythm
of the respiration, cold sweat, rise in body temperature,
tremor, pallor, erection of the hair, suspension of the principal
functions of digestion, muscular relaxation, and staring of the eyes
(Fig. 12). The functions of the brain are wholly suspended except those
which relate to the self-protective response against the feared object.
Neither the brain nor any other organ of the body can respond
to any other lesser stimulus during the dominance of fear.

From these premises it would appear that under the influence
of fear, most, perhaps all, of the organs of the body are divided
sharply into two classes:  First, those that are stimulated,
and, second, those that are inhibited.  Those that are stimulated
are the entire muscular system, the vasomotor and locomotor systems,
the senses of perception, the respiration, the mechanism for erecting
the hair, the sweat-glands, the thyroid gland, the adrenal gland
(Cannon), and the special senses.  On the other hand,
all the digestive and procreative functions are inhibited.
What is the significance of this stimulation of some and inhibition
of other organs?  As far as we know, the stimulated organs
increase the efficiency of the animal for fight or for flight.
It is through skeletal muscles that the physical attack or escape
is effected; these muscles alone energize the claws, the teeth,
the hoofs, and the means for flight.  The increased action of the
muscles of the heart and the blood-vessels increases the efficiency
of the circulation; the secretion of the adrenal gland causes a rise
in the blood-pressure; the increased action of the thyroid gland causes
an increased metabolic activity; there is evidence that glycogen
is actively called out, this being the most immediately available
substance for the production of energy; the increased activity
of the respiration is needed to supply the greater need of oxygen
and the elimination of the increased amount of waste products;
the dilatation of the nostrils affords a freer intake of air;
the increased activity of the sweat-glands is needed to regulate
the temperature of the body which the increased metabolism causes to rise.
The activity of all the organs of perception--sight, hearing, smell--
is increased in order that the danger may be more accurately perceived.
It cannot be a mere coincidence that the organs and the tissues
that are stimulated in the emotion of fear are precisely those that
are actually utilized in a physical struggle for self-preservation.

Are any other organs stimulated by fear except those that can
or that do assist in making a defensive struggle?  I know of none.
On the other hand, if an animal could dispense with his bulky
digestive organs, whose functions are suspended by fear, if he could,
so to speak, clear his decks for battle, it would be to his advantage.
Although the marvelous versatility of natural selection apparently
could devise no means of affording this advantage, it nevertheless shut
off the nervous current and saved the vital force which is ordinarily
consumed by these non-combatants in the performance of their functions.
Whatever may be the origin of fear, its phenomena are due to a
stimulation of all the organs and tissues that add to the efficiency
of the physical struggle for self-preservation and an inhibition
of the func-


{illust. caption = FIG.  19--THE BROAD JUMP.  Note the similarity
of the expression to the facial expression of fear and of anger
(Figs. 12 and 21). (Wm. J. Brownlow, drawn from photo.)
tions of the leading organs that do not participate in that struggle--
the non-combatants, so to speak.  Fear arose from injury,
and is one of the oldest and surely the strongest emotion.
By the slow process of vast empiricism nature has evolved the
wonderful defensive motor me-chanism of many animals and of man.
The stimulation of this mechanism leading to a physical struggle is action,
and the stimulation of this mechanism without action is emotion.
We may say, therefore, that fear is a PHYLOGENETIC FIGHT OR FLIGHT (Fig.
18). On this hypothesis all the organs and parts {illust. caption
= FIG.  20.-FINISH OF RELAY RACE.

Compare the facial expression of the runners with those in Figs.
12, 19, 22.  These pictures illustrate the fact that the same
mechanism is stimulated in emotion as in physical action.
(Photo by Underwood and Underwood, N. Y.)}


of the body are integrated, connected, or correlated for the
self-preservation of the individual by the activity of his motor mechanism
(Figs. 12, 19, and 20). We fear not in our hearts alone, not in our
brains alone, not in our viscera alone--fear influences every organ
and tissue; each organ or tissue is stimulated or inhibited according
to its use or hindrance in the physical struggle for existence.
By thus concentrating all or most of the nerve force on the nerve-muscular
mechanism for defense, a greater physical power is developed.
Hence it is that under the stimulus of fear animals are able to perform
preternatural feats of strength.  For the same reason, the exhaustion
following fear will be increased as the powerful stimulus of fear drains
the cup of nervous energy even though no visible action may result.
An animal under the stimulus of fear may be likened to an automobile
with the clutch thrown out but whose engine is racing at full speed.
The gasoline is being consumed, the machinery is being worn,
but the machine as a whole does not move, though the power of its
engine may cause it to tremble.

When this conception is applied to the human beings of today,
certain mysterious phenomena are at once elucidated.  It must be borne
in mind that man has not been presented with any new organs to meet
the requirements of his present state of civilization; indeed, not only
does he possess organs of the same type as those of his savage fellows,
but of the same type also as those possessed by the lower animals even.
In fact, man has reached his present status of civilization with
the primary equipment of brutish organs.  Perhaps the most striking
difference between man and animals lies in the greater control
which man has gained over his primitive instinctive reactions.
As compared with the entire duration of organic evolution,
man came down from his arboreal abode and assumed his new role
of increased domination over the physical world but a moment ago.
And now, though sitting at his desk in command of the complicated
machinery of civilization, when he fears a business catastrophe
his fear is manifested in the terms of his ancestral physical battle
in the struggle for existence.  He cannot fear intellectually,
he cannot fear dispassionately, he fears with all his organs,
and the same organs are stimulated and inhibited as if, instead of it
being a battle of credit, of position, or of honor, it were a physical
battle with teeth and claws.  Whether the cause of acute fear
be moral, financial, social, or stage fright, the heart beats wildly,
the respirations are accelerated, perspiration is increased,
there are pallor, trembling, indigestion, dry mouth, etc.
The phenomena are those which accompany physical exertion
in self-defense or escape.  There is not one group of phenomena
for the acute fear of the president of a bank in a financial
crash and another for the hitherto trusted official who suddenly
and unexpectedly faces the imminent probability of the penitentiary;
or one for a patient who unexpectedly finds he has a cancer
and another for the hunter when he shoots his first big game.
Nature has but one means of response to fear, and whatever its cause
the phenomena are always the same--always physical.

If the stimulus of fear be repeated from day to day, whether in
the case of a mother anxious on account of the illness of a child;
a business man struggling against failure; a politician under contest
for appointment; a broker in the daily hazard of his fortune;
litigants in legal battle, or a jealous lover who fears a rival;
the countless real as well as the baseless fears in daily life,
in fact, all forms of fear, as it seems to me, express themselves
in like terms of ancestral physical contests.  On this law,
fear dominates the various organs and parts of the body.

Anger and fear express opposite emotional states.  Fear is the
expression of a strong desire to escape from danger; anger, of a
strong desire to attack physically and to vanquish opposition.
This hypothesis is strongly supported by the outward expressions
of fear and of anger.  When the business man is conducting a struggle
for existence against his rivals, and when the contest is at
its height, he may clench his fists, pound the table, perhaps show
his teeth, and exhibit every expression of physical combat.
Fixing the jaw and showing the teeth in anger merely emphasize
the remarkable tenacity of phylogeny.  Although the development
of the wonderful efficiency of the hands has led to a modification
of the once powerful canines of our progenitors, the ancestral use
of the teeth for attack and defense is attested in the display of anger.
In all stations of life differences of opinion may lead to argument
and argument to physical combats, even to the point of killing.
The physical violence of the savage and of the brute still lies
surprisingly near the surface (Fig. 21).

We have now presented some of the reasons based largely on gross animal
behavior why fear is to be regarded as a response to phylogenetic
association with physical danger.  In further support of this hypothesis,
I shall now present some clinical and experimental evidence.
Although there is not convincing proof, yet there is evidence that
the effect of the stimulus of fear upon the body when unaccompanied
by physical activity is more injurious than is an actual physical
contest which results in fatigue without gross physical injury.
It is well known that the soldier who, while under fire,
waits in vain for orders to charge, suffers more than the soldier
who flings himself into the fray; and that a wild animal endeavoring
to avoid capture suffers less than one cowering in captivity.
An unexpressed smouldering emotion is measurably relieved by action.
It is probable that the various energizing substances needed in
physical combat, such as the secretions of the thyroid, the adrenals
(Cannon), etc., may cause physical injury to the body when they
are not consumed by action (Fig. 22).

That the brain is definitely influenced--damaged even--
by fear has been proved by the following experiments:
Rabbits were frightened by a dog but were neither injured nor chased.
After various periods of time the animals were killed and their
brain-cells compared with the brain-cells of normal animals--
wide-spread changes were seen (Fig. 13). The principal clinical phenomena
expressed by the rabbit were rapid heart, accelerated respiration,
prostration, tremors, and a rise in temperature.  The dog showed
similar phenomena, excepting that, instead of such muscular relaxation
as was shown by the rabbit, it exhibited aggressive muscular action.
Both the dog and the rabbit were exhausted but, although the dog
exerted himself actively and the rabbit remained physically passive,
the rabbit was much more exhausted.

Further observations were made upon the brain of a fox
which had been chased for two hours by members of a hunt club,
and had been finally overtaken by the hounds and killed.
Most of the brain-cells of this fox, as compared with those of a
normal fox, showed extensive physical changes (Fig. 4).

The next line of evidence is offered with some reservation,
but it has seemed to me to be more than mere idle speculation.
It relates to the phenomena of one of the most interesting diseases
in the entire category of human ailments--I refer to exophthalmic goiter,
or Graves' disease, a disease primarily involving the emotions.
This disease is frequently the direct sequence of severe
mental shock or of a long and intensely worrying strain.
The following case is typical:  A broker was in his usual health up
to the panic of 1907; during this panic his fortune and that of others
were for almost a year in jeopardy, failure finally occurring.
During this heavy strain he became increasingly nervous and by
imperceptible degrees there developed a pulsating enlargement of
the thyroid gland, an increased prominence of the eyes, marked increase
in perspiration--profuse sweating even--palpitation of the heart,
increased respiration with frequent sighing, increase in blood-pressure;
there were tremor of many muscles, rapid loss of weight and strength,
frequent gastro-intestinal disturbances, loss of normal control
of his emotions, and marked impairment of his mental faculties.
He was as completely broken in health as in fortune.
These phenomena resembled closely those of fear and followed
in the wake of a strain which was due to fear.

In young women exophthalmic goiter often follows in the wake
of a disappointment in love; in women, too, it frequently follows
the illnesses of children or parents during which they have had
to endure the double strain of worry and of constant care.
Since such strains usually fall most heavily upon women, they are
the most frequent victims of this disease.  Now, whatever the exciting
cause of exophthalmic goiter, whether it be unusual business worry,
disappointment in love, a tragedy, or the illness of a loved one,
the symptoms are alike and closely resemble the phenomena of one
of the great primitive emotions.  How could disappointment in love
play a role in the causation of Graves' disease?  If the hypothesis
which has been presented as an explanation of the genesis and
the phenomena of fear be correct, then that hypothesis explains
also the emotion of love.  If fear be a phylogenetic physical
defense or escape which does not result in muscular action,
then love is a phylogenetic conjugation without physical action.
The quickened pulse, the leaping heart, the accelerated respiration,
the sighing, the glowing eye, the crimson cheek, and many other
phenomena are merely phylogenetic recapitulations of ancestral acts.
The thyroid gland is believed to participate in such physical activities.
Hence it may well follow that the disappointed maiden who is intensely
integrated for a youth will, at every thought of him, be subjected
by phylogenetic association to a specific stimulation analogous
to that which attended the ancestral consummation.  Moreover, a happy
marriage has many times been followed by a cure of the exophthalmic
goiter which appeared in the wake of such an experience.

The victims of Graves' disease present a counterpart of
emotional exhaustion.  That the emotions in Graves' disease are
abnormally acute is illustrated by my personal observation
of the death of a subject of this disease from fear alone.
Whatever the exciting cause of this disease, the symptoms are the same;
just as in fear, the phenomena are the same whatever the exciting cause.

Figures 12 and 16 show the resemblance between the outward appearances
of a patient with Graves' disease and of a person obsessed by fear.
Fear and Graves' disease have the following phenomena in common:
Increased heart-beat, increased respiration, rising temperature,
muscular tremors, protruding eyes, loss in weight; Cannon has found
an increased amount of adrenalin in the blood in fear and Frankel
in Graves' disease; increased blood-pressure; muscular weakness;
digestive disturbances; impaired nervous control; hypersusceptibility
to stimuli; in protracted intense fear the brain-cells show marked
physical changes, and in Graves' disease analogous changes are seen
(Figs. 13 C and 15). In Graves' disease there seems to be a composite
picture of an intense expression of the great primitive emotions.
If Graves' disease be a disease of the great primitive emotions,
or rather of the whole motor mechanism, how is the constant flow
of stimulation of this complicated mechanism supplied?  It would
seem that there must be secreted in excessive amount some substance
that activates the motor mechanism.  The nervous system in Graves'
disease is hypersusceptible to stimuli and to thyroid extract.
It might follow that even a normal amount of thyroid secretion would
lead to excessive stimulation of the hypersusceptible motor mechanism.

This condition of excessive motor activity and hyperexcitability may
endure for years.  What is the source of this pathologic excitation?
The following facts may give a clue.  In suitable cases of Graves'
disease, if the thyroid secretion is sufficiently diminished by a removal
of a part of the gland or by interrupting the nerve and the blood supply,
the phenomena of the disease are diminished immediately, and in favorable
cases the patient is restored to approximately the normal condition.
The heart action slows, the respiratory rate falls, the restlessness
diminishes, digestive disturbances disappear, tremors decrease,
there is a rapid increase in the body weight, and the patient gradually
resumes his normal state.  On the other hand, if for a period
of time extract of the thyroid gland is administered to a normal
individual in excessive dosage, there will develop nervousness,
palpitation of the heart, sweating, loss of weight, slight protrusion
of the eyes, indigestion; in short, most of the phenomena of Graves'
disease and of the strong emotions will be produced artificially
(Figs. 15 and 23). When the administration of the thyroid extract
is discontinued, these phenomena may disappear.  On the other hand,
when there is too little or no thyroid gland, the individual
becomes dull, stupid, and emotionless, though he may be irritable;
while if a sufficient amount of thyroid extract be given to such
a patient he may be brought back to his normal condition.

Hence we see that the phenomena of the emotions may within certain
limits be increased, diminished, or abolished by increasing,
diminishing, or totally excluding the secretion of the thyroid gland.

Graves' disease may be increased by giving thyroid extract and by fear.
It may be diminished by removing a part of the gland, or by
interrupting the blood and nerve supply, or by complete rest.
In addition, at some stage of Graves' disease there is an
increase in the size and in the number of the secreting cells.
These facts regarding the normal and the pathologic supply of thyroid
secretion point to this gland as one of the sources of the energizing
substance or substances, by means of which the motor phenomena
of animals are executed and their emotions expressed.

Anger is similar to fear in origin and, like fear, is an integration
and stimulation of the motor mechanism and its accessories.
Animals which have no natural weapons for attack experience neither
fear nor anger, while the animals which have weapons for attack
express anger principally by energizing the muscles used in attack.
Although, as has already been stated, the efficiency of the hands
of man has largely supplanted the use of the teeth, he still shows
his teeth in anger and so gives support to the theory that this
emotion is of remote ancestral origin and proves the great persistence
of phylogenetic association.  On this conception we can understand
why it is that a patient consumed by worry--which to me signifies
interrupted stimulation, a state of alternation between hope
and fear--suffers so many bodily impairments and diseases even.
This hypothesis explains the slow dying of animals in captivity.
It explains the grave digestive and metabolic disturbances which
appear under any nerve strain, especially under the strain of fear,
and the great benefits of confidence and hope; it explains the nervousness,
loss of weight, indigestion--in short, the comprehensive physical
changes that are wrought by fear and by sexual love and hate.
On this hypothesis we can understand the physical influence
of one individual over the body and personality of another;
and of the infinite factors in environment that, through phylogenetic
association, play a role in the functions of many of our organs.
It is because under the uncompromising law of survival of the fittest
we were evolved as motor beings that we do not possess any organs or
faculties which have not served our progenitors in accomplishing their
survival in the relentless struggle of organic forms with one another.
We are now, as we were then, essentially motor beings, and the only way in
which we can meet the dangers in our environment is by a motor response.
Such a motor response implies the integration of our entire being
for action, this integration involving the activity of certain glands,
such as the adrenals (Cannon), the thyroid, the liver, etc., which throw
into the blood-stream substances which help to form energy, but which,
if no muscular action ensues, are harmful elements in the blood.
While this motor preparation is going on, the entire digestive
tract is inhibited.  It thus becomes clear why an emotion is more
harmful than action.

Any agency that can sufficiently inspire faith,--dispel worry,--
whether that agency be mystical, human, or divine, will at once
stop the body-wide stimulations and inhibitions which cause
lesions which are as truly physical as is a fracture.
The striking benefits of good luck, success, and happiness;
of a change of scene; of hunting and fishing; of optimistic
and helpful friends, are at once explained by this hypothesis.
One can also understand the difference between the broken body
and spirits of an animal in captivity and its buoyant return to its
normal condition when freed.

But time will not permit me to follow this tempting lead, which has
been introduced for another purpose--the proposal of a remedy.

Worries either are or are not groundless.  Of those that have
a basis, many are exaggerated.  It has occurred to me to utilize
as an antidote an appeal to the same great law that originally
excited the instinctive involuntary reaction known as fear--
the law of self-preservation.

I have found that if an intelligent patient who is suffering from
fear can be made to see so plainly as to become firmly convinced
that his brain, his various organs, indeed his whole being,
could be physically damaged by fear, that this same instinct of
self-preservation will, to the extent of his conviction, banish fear.
It is hurling a threatened active militant danger, whose injurious
influences are both certain and known, against an uncertain,
perhaps a fancied, one.  In other words, fear itself is an injury
which when recognized is instinctively avoided.  In a similar manner
anger may be softened or banished by an appeal to the stronger
self-preserving instinct aroused by the fear of physical damage,
such as the physical injury of brain-cells. This playing of one
primitive instinct against another is comparable to the effect
produced upon two men who are quarreling when a more powerful enemy
of both comes threateningly on the scene.

The acute fear of a surgical operation may be banished by the use
of certain drugs that depress the associational power of the brain and
so minimize the effect of the preparations that usually inspire fear.
If, in addition, the entire field of operation is blocked by local
anesthesia so that the associational centers are not awakened,
the patient will pass through the operation unscathed.

The phylogenetic origin of fear is injury, hence injury and fear cause
the same phenomena.  In their quality and in their phenomena psychic
shock and traumatic shock are the same.  The perception of danger
by the special senses in the sound of the opening gun of a battle,
or in the sight of a venomous snake, is phylogenetically the same
and causes the same effects upon the entire body as an operation under
anesthesia or a physical combat in that each drives the motor mechanism.
The use of local anesthetics in the operative field prevents
nerve-currents from the seat of injury from reaching the brain and there
integrating the entire body for a self-defensive struggle.  The result,
even though a part of the brain is asleep and the muscles paralyzed,
is the same as that produced by the interception of the terrifying
sound of the gun, or of the sight of the dangerous reptile,
since the stimulation of the motor mechanism is prevented.

By both the positive and the negative evidence we are forced
to believe that the emotions are primitive instinctive reactions
which represent ancestral acts; and that they therefore utilize
the complicated motor mechanism which has been developed by the forces
of evolution as that best adapted to fit the individual for his
struggle with his environment or for procreation.

The mechanism by which the motor acts are performed and the mechanism
by which the emotions are expressed are one and the same.
These acts in their infinite complexity are suggested by association--
phylogenetic association.  When our progenitors came in contact
with any exciting element in their environment, action ensued then
and there.  There was much action--little restraint or emotion.
Civilized man is really in auto-captivity. He is subjected
to innumerable stimulations, but custom and convention frequently
prevent physical action.  When these stimulations are sufficiently
strong but no action ensues, the reaction constitutes an emotion.
A phylogenetic fight is anger; a phylogenetic flight is fear;
a phylogenetic copulation is sexual love, and so one finds in this
conception an underlying principle which may be the key to an
understanding of the emotions and of certain diseases.



PAIN, LAUGHTER, AND CRYING[*]

[*] Address delivered before the John Ashhurst, Jr.. Surgical Society
of the University of Pennsylvania, May 3, 1912.

PAIN


Pain, like other phenomena, was probably evolved for a particular purpose--
surely for the good of the individual; like fear and worry,
it frequently is injurious.  What then may be its purpose?

We postulate that pain is one of the phenomena which result
from a stimulation to motor action.  When a barefoot boy steps
on a sharp stone it is important that the injuring contact be
released as quickly as possible; and therefore physical injury pain
results and impels the required action.  Anemia of the soft parts
at the points of pressure results from prolonged sitting or lying
in one position, and as a result pain compels a muscular action
that shifts the damaging pressure--this is the pain of anemia;
when the rays of the blazing sun shine directly upon the retina,
pain immediately causes a protective muscular action--the lid is closed,
the head turns away--this is light pain; when standing too close
to a blazing fire the excessive heat causes a pain which results
in the protective muscular action of moving away--this is heat pain;
when the urinary bladder is acutely overdistended the resultant
pain induces voluntary as well as involuntary muscular contraction--
this is evacuation pain; associated with defecation is a characteristic
warning pain, and an active pain which induces the required
muscular action--this, like the pain accompanying micturition,
is an evacuation pain; in obstruction of the urinary passages
and of the large and the small intestine the pain is exaggerated,
as is the accompanying muscular contraction--this is a pathologic
evacuation pain; when the fetus reaches full term and labor is
to begin, it is heralded by pain which is associated with rhythmic
contractions of the uterine muscle; later, many other muscles
take part in the birth and pain is associated with all these
muscular contractions--these are labor pains; when a foreign body,
be it ever so small, falls upon the conjunctiva or cornea there
results what is perhaps the acutest pain known, and quick and active
muscular action follows--this is special contact pain.  Special pain
receptors are placed in certain parts of the nose, the pharynx,
and the larynx, the stimulation of which causes special motor acts,
such as sneezing, hawking, coughing.  Curiously vague pains are
associated with the protective motor act of vomiting and with the sexual
motor acts--these may be termed nausea pains and pleasure pains.
We now see, therefore, that against the injurious physical contacts
of environment, against heat and cold, against damaging sunlight,
against local anemia when resting or sleeping, the body is protected
by virtue of the muscular action which results from pain.
Then, too, for the emptying of the pregnant uterus, for the evacuation
of the intestine and of the urinary bladder as normal acts,
and for the overcoming of obstructions in these tracts,
pain compels the required muscular actions, For passing gall-stones
and urinary calculi, urgent motor stimuli are awakened by pain.
For each of these diversified pains the consequent muscular action
is specific in type, distribution, and intensity.  This statement
is so commonplace that we are apt to miss the significance and
the wonder of it.  It is probable that every nerve-ending in the skin
and every type of stimulation represents a separate motor pattern,
the adequate stimulation of which causes always the same response.

Let us pass on to the discussion of another and perhaps even
more interesting type of pain, that associated with infection.
Not all kinds of infection are painful; and in those infections
that may be associated with pain there is pain only when certain
regions of the body are involved.  Among the infections that are not
associated with pain are scarlet fever, typhoid fever, measles, malaria,
whooping-cough, typhus fever, and syphilis in its early stages.
The infections that are usually, though not always, associated with
pain are the pyogenic infections.  The pyogenic infections
and the exanthemata constitute the great majority of infections
and are the basis of the discussion which follows.

I will state one of my principal conclusions first, _i.
e_., that the only types of infection that are associated with pain
are those in which the infection may be spread by muscular action
or those in which the fixation of parts by continued muscular
rigidity is an advantage; and, further, as a striking corollary,
that the type of infection that may cause muscular action when it
attacks one region of the body may cause no such action when it
attacks another region.

The primary, and perhaps the most striking, difference between
the painless exanthemata and the painful pyogenic infections is that
in the case of the exanthemata the protective response of the body
is a chemical one,--the formation of antibodies in the blood,
which usually produce permanent immunity,--while the response to the
pyogenic infections is largely phagocytic.  In the pyogenic infections,
in order to protect the remainder of the body, which, of course,
enjoys no immunity, every possible barrier against the spread
of the infection is thrown about the local point of infection.
How are these barriers formed?  First, lymph is poured out, then the part
is fixed by the continuous contraction of the neighboring muscles
and by the inhibition of those muscles that, in the course of their
ordinary function, would by their contractions spread the infection.
Wherever there is protective muscular rigidity there is also pain.
On the other hand, in pyogenic infections in the substance
of the liver, in the substance of the kidney, within the brain,
in the retroperitoneal space, in the lobes of the lung, in the chambers
of the heart and in the blood-vessels of the chest and the abdomen,
in all locations in which muscular contractions can in no way assist
in localizing the disease, pyogenic infections produce no muscular
rigidity and no pain.  Apparently, therefore, only those infections are
painful which are associated with a protective muscular contraction.
This explains why tuberculosis of the hip is painful, while tuberculosis
of the lung is painless.

There is a third type of pain which modifies muscular action
in a curious way.  We have already stated that local pain serves
an adaptive purpose.  In this light let us now consider headache.
Headache is one of the commonest initiatory symptoms of the
various infections, especially of those infections which are
accompanied by no local pain and by no local muscular action.
In peritonitis, cholecystitis, pleurisy, arthritis, appendicitis,
salpingitis, child-birth, in obstructions of the intestinal
and the genito-urinary tract, in short, in those acute processes
in which the local symptoms are powerful enough to govern
the individual as a whole,--to make him lie down and keep quiet,
refuse food and possibly reject what is already in the stomach,--
in all these conditions there is rarely a headache, but in the diseases
in which local pain is absent, such as the exanthemata, typhoid fever,
and auto-intoxication, which have no dominating local disturbances
to act as policemen to put the individual to bed and to make him
refuse food that he may be in the most favorable position to combat
the oncoming disease, in such cases in which these masterful and
beneficent local influences are absent we postulate that headache
has been evolved to perform this important service.

On the hypothesis that it is good for the individual who is acutely
stricken by a disease or who is poisoned by autointoxication to rest
and fast, and that the muscular system obeys the imperial command
of pain, and in view of the fact that the brain is not only in constant
touch with the conditions of every part of the body but that it
is also the controlling organ of the body, one would expect that in
these diseases the major pain whose purpose it is to govern general
muscular action would be located in the head and there we find it.
How curious and yet how intelligible is the fact that, though a
headache may be induced by even a slight auto-intoxication,
an abscess may exist within the brain without causing pain.
When an obliterative endarteritis is threatening a leg with
anemic gangrene, or when one lies too long in the same position on
a hard bed, there is threatening injury from local anemia, and as a
result there is acute pain, but when the obliterative endarteritis
threatens anemia of the brain, or when an embolism or thrombosis has
produced anemia of the brain, there may be no accompanying pain.
The probable explanation of the pain which results in the first instance
and the lack of pain in the second is that in the former muscular action
constitutes a self-protective response, but in the other it does not.
Diseases and injuries of the brain are notoriously difficult
to diagnosticate.  This may well be because it has always been so well
protected by the skull that there have been evolved within it few
tell-tale self-protective responses, so that in the presence of injury
and disease within itself the brain remains remarkably silent.
It should occasion no surprise that there are in the brain no receptors,
the mechanical stimulation of which can cause pain, because its bony
covering has always prevented the adaptive implantation within it
of contact pain receptors.  Dr. Frazier tells me that in the course
of his operations on the brains of unanesthetized patients
he is able to explore the entire brain freely and without pain.
From my own experience I am able to confirm Dr. Frazier's observation.
In addition, the two-stage operation for the excision of the Gasserian
ganglion provides an observation of extraordinary interest.
If at the first seance the ganglion is exposed, but is not disturbed
except by the iodoform gauze packing, then on the following
day the gauze may be removed, the ganglion picked up, and its
branches and root excised without anesthesia and without pain.
The same statement and explanation may be made regarding the distribution
of pain receptors for physical contact within the parenchyma of the liver,
the gall-bladder, the abdominal viscera, the spleen, the heart,
the lungs, the retroperitoneal tissue, the deep tissue of the back,
the vertebrae, and in certain portions of the spinal cord.
Just what is the distribution of the receptors for heat and for cold
I am unable to state, but this much we do know, that without
anesthesia the intestines may be cauterized freely without the least
pain resulting, and in animals the cauterization of the brain causes
no demonstrable change in the circulatory or respiratory reactions.
It is probable therefore that the distribution of the pain receptors
for physical contact and for heat are limited to those parts of the body
that have been exposed to injurious contacts with environment.

Of special significance is the pain which is due to cold,
which increases muscular tone and produces shivering.  The general
increase in muscular tone produces an interesting postural phenomenon:
the limbs are flexed and the body bent forward, a position which probably
is due to the fact that the flexors are stronger than the extensors.
As muscular action is always accompanied by heat production,
the purpose of the muscular contraction and the shivering
is quite certainly caused by cold to assist in the maintenance
of the normal body temperature.

We have now discussed many of the causes of pain and in each instance
we have found an associated muscular action which apparently
serves some adaptive purpose (Figs. 24 and 25). If we assume
that pain exists for the purpose of stimulating muscular reactions,
we may well inquire what part of the nervous are is the site of
the sensation of pain--the nerve-endings, the trunk, or the brain?
Does pain result from physical contact with the nerve-endings, with
the physical act of transmitting an impression along the nerve trunk,
or with the process within the brain-cells by which energy is released
to cause a motor act?

It seems most probable that the site of the pain is in the brain-cells.
If this be so, then what is the physical process by which the
phenomena of pain are produced?  The one hypothesis that can be
tested experimentally is that pain is a phenomenon resulting from
the rapid discharge of energy in the brain-cells. If this be true,
then if every pain receptor of the body were equally stimulated
in such a manner that


{illust. caption = FIG.  25.--FEAR AND AGONY.  "Amid this dread
exuberance of woe ran naked spirits wing'd with horrid fear."--
Dante's "Inferno," Canto XXIV, lines 89, 90.  all the stimuli
reached the brain-cells simultaneously, the cells would find
themselves in equilibrium and no motor act would be performed.
But if all the pain receptors of the body but one were equally stimulated,
and this one stimu-lated harder than the rest, then the latter
would gain possession of the final common path, the sensation
of pain would be felt, and a muscular contraction would result.
It is well known that when a greater pain is thrown into
competition with a lesser one, the lesser is completely submerged.
In this manner the school-boy initiates the novice into the mystery
of the painless plucking of hair.  The simultaneous, but severe
application of the boot to the blindfolded victim takes complete
and exclusive possession of the final common path and the hair
is painlessly plucked through the triumph of the boot stimulus over
the hair stimulus in the struggle for the possession of the final
common path.  Another argument in favor of this hypothesis that
pain is an accompaniment of the release of energy in the brain-
cells is found in the fact that painless stimuli received through
the special senses may completely submerge the painful stimuli
of physical injury; for although the stimuli to motor action,
which are received through the senses of sight, hearing, and smell,
cause even more powerful motor action than those caused by
physical contact stimuli, yet they are not accompanied by pain.
Examples of this triumph of stimulation of the special senses over
contact stimulation are frequently seen in persons obsessed by anger
or fear, and to a less degree in those obsessed by sexual emotion.
In the fury of battle the soldier may not perceive his wound until
the emotional excitation is wearing away, when the sensation
of warm blood on the skin may first attract his attention.
Religious fanatics are said to feel no pain when they subject themselves
to self-injury. Now, since both psychic and mechanical stimuli cause motor
action by the excitation ofprecisely the same mechanism in the brain,
and since the more rapid release of energy from psychic stimuli
submerges the physical stimuli and prevents pain, it would seem
that pain must be a phenomenon which is associated with the process
of releasing energy by the brain-cells. Were physical injury inflicted
in a quiescent state equal to that inflicted in the emotional state,
great pain and intense muscular action would be experienced.
Now the emotions are as purely motor excitants as is pain.
The dynamic result is the same the principal difference being the greater
suddenness and the absolute specificity of the pain stimuli as compared
with the more complex and less peremptory stimuli of the emotions.
A further evidence that pain is a product of the release of brain-cell
energy is the probability that if one could pierce the skin at
many points on a limb in such a manner that antagonistic points
only were equally and simultaneously stimulated, then an equilibrium
in the governing brain- cells would be established and neither
pain nor motion would follow.  An absolute test of this assumption
cannot be made but it is supported by the obtainable evidence.
We will now turn to a new viewpoint, a practical as well as a
fascinating one, which can best be illustrated by two case histories:
A man, seventy-eight years old, whose chief complaint was obstinate
constipation, was admitted to the medical ward of the Lakeside Hospital
several years ago.  The abdomen was but slightly distended;
there was no fever, no increased leukocytosis, no muscular rigidity,
and but slight general tenderness.  He claimed to have lost in weight
and strength during the several months previous to his admission.
A tentative diagnosis of malignant tumor of the large intestine was made,
but free movements weresecured rather easily, and we abandoned
the idea of an exploratory operation.  The patient gradually failed
and died without a definite diagnosis having been made by either
the medical or the surgical service.  At autopsy there was found
a wide-spread peritonitis arising from a perforated appendix.
A child, several years old, was taken ill with some indefinite disease.
A number of the ablest medical and surgical consultants of a leading
medical center thoroughly and repeatedly investigated the case.
Although they could make no definite diagnosis they all
agreed that the trouble surely could not be appendicitis
because there was neither muscular rigidity nor tenderness.
The autopsy showed a gangrenous appendix and general peritonitis.
How can these apparently anomalous cases be explained?
These two cases are illustrations of the same principle that underlies
the freedom from pain which results from the use of narcotics
and anesthetics, the same principle that explains the fact that
cholecystitis may occur in the aged without any other local symptoms
than the presence of a mass and perhaps very slight tenderness;
and that accounts in general for the lack of well-expressed disease
phenomena in senility and in infancy.  The reason why the aged,
the very young, and the subjects of general paresis show but few
symptoms of disease is that in senility the brain is deteriorated,
while in infancy the brain is so undeveloped that the mechanism
of association is inactive, hence pain and tenderness,
which are among the oldest of the associations, are wanting.
Senility and infancy are by nature normally narcotized.
The senile are passing through the twilight into the night;
while infants are traversing through the dawn into the day.
Hence it is that the diagnosis of injury and disease in the extremes
oflife is beset by especial difficulties, since the entire body
is as silent as are the brain, the pericardium, the mediastinum,
and other symptomless areas.  For the same reason, when a patient
who is seriously ill with a painful disease turns upon the physician
a glowing eye and an eager face, and remarks how comfortable he feels,
then the end is near.  This is a brilliant and fateful clinical mirage.
When one reflects on the vast amount of evidence as to the origin
and the purpose of pain, he is forced to conclude that pain is
a phenomenon of motor stimulation, and that its principal role is
the protection of the individual against the gross and the microscopic
enemies in his environment.  The benefits of pain are especially
manifested in the urgent muscular actions by means of which the body
moves away from physical injury; obstructions of the hollow
viscera are overcome; rest is compelled in the acute infections--
the infected points are held rigidly quiet, the muscles of the abdomen
are fixed, and harmful peristalsis is arrested in peritonitis;
while there is absolutely no pain in the diseases or injuries
which affect those regions of the body in which in the course
of evolution no pain receptors were placed, or in those diseases
in which muscular inhibition or contraction is of no help.
In a biologic sense pain is closely associated with the emotional stimuli,
for both pain and the emotions incite motor activity for the good
of the individual.  The frequent occurrence of post-operative and
post- traumatic pain is accounted for by the fact that the operation
or the injury has lowered the threshold of the brain- cells to trauma;
the brain and not the local sensitive field is the site of the pain.
I have found that, by blockingthe field of operation with
local anesthesia, post-operative pain is diminished; that is,
since the local anesthesia prevents the strong stimuli of the
trauma from reaching the brain, its threshold is not lowered.
There is a close resemblance between the phenomena of pain habit,
of education, of physical training, of love and of hate.  In education,
in pain habit, in all emotional relations, a low brain- cell threshold
is established which facilitates the reception of specific stimuli;
all these processes are motor acts, or are symbolic of motor acts,
and we may be trained to perceive misfortune and pain as readily as we
are trained to perceive mathematical formulae or moral precepts.
In each and every case, readiness of perception depends, as it seems to me,
upon a modified state of the brain-cells, their threshold especially,
the final degree of perception possible in any individual being perhaps
based on the type of potential molecules of which the brain is built.
We must believe also that every impression is permanent, as only thus
could an individual animal or a man be fitted by his own experience
for life's battles.  LAUGHTER AND CRYING What is laughter?
What is its probable origin, its distribution, and its purpose?
Laughter is an involuntary rhythmic contraction of certain
respiratory muscles, usually accompanied by certain vocal sounds.
It is a motor act of the respiratory apparatus primarily, although if
intense it may involve not only the extraordinary muscles of respiration,
but most of the muscles of the body.  There are many degrees
of laughter, from the mere brightening of the eyes, a fleeting smile,
tittering andgiggling, to hysteric and convulsive laughter.
Under certain circumstances, laughter may be so intense and
so long continued that it leads to considerable exhaustion.
The formation of tears is sometimes associated with laughter.
When integrated with laughter, the nervous system can perform
no other function.  Crying is closely associated with laughter,
and in children especially laughter and crying are readily interchanged.
We postulate that laughter and weeping serve a useful purpose.
According to Darwin, only man and monkeys laugh (Fig. 26);
other animals exhibit certain types of facial expression accompanying
various emotions, but laughter in the sense in which that word
is commonly used is probably an attribute of the primates only,
although it is probable that many animals find substitutes for laughter.
The proneness of man to laughter is modified by age, sex, training,
mental state, health, and by many other factors.  Healthy, happy children
are especially prone to laughter, while disease, strong emotions,
fatigue, and age diminish laughter.  Women laugh more than do men.
The healthy, happy maturing young woman perhaps laughs most, especially
when she is slightly embarrassed.  What causes laughter?  Good news,
high spirits, tickling, hearing and seeing others laugh; droll stories;
flashes of wit; passages of humor; averted injury; threatened breach
of the conventions; and numerous other causes might be added.
It is obvious that laughter may be produced by diverse influences,
many of which are so unlike each other that it would at first sight
seem improbable that a single general principle underlies all.
Before presenting a hypothesis which harmonizes most of the facts,
and which mayoffer an explanation of the origin and purpose of laughter,
let us return for a moment to some previous considerations--
that man is essentially a motor being; that all his responses to
the physical forces of his environment are motor; {illust. caption
= FIG.  26.--LAUGHING CHIMPANZEE.  "Mike," the clever chimpanzee
in the London Zoo, evidently enjoys a joke as well as any one else.
(Photo by Underwood and Underwood, N. Y.)}


that thoughts and words even are symbolic of motor acts;
that in the emotions of fear, of anger, and of sexual love
the whole body is integrated for acts which are not performed.
These integrations stimulate the brain-cells, the ductless glands,
and other parts, and the energizing secretions, among which are epinephrin,
thyroid and hypophyseal secretions, are thrown into the blood-stream,
while that most available fuel, glycogen, is also mobilized in the blood.
This body-wide preparation for action may be designated kinetic reaction.
The fact that emotion is more injurious to the body than is
muscular action is well known, the difference being probably caused
by the fact that when there is action the above-mentioned products
of stimulation are consumed, while in stimulation without action
they are not consumed and must be eliminated as waste products.
Now these activating substances and the fuel glycogen may be consumed
by any muscular action as well as by the particular muscular action
for which the integration and consequent stimulation were made;
that is, if one were provoked to such anger that he felt impelled
to attack the object of his anger, one of three things might happen:
First, he might perform no physical act but give expression to
the emotion of anger; second, he might engage in a physical struggle
and completely satisfy his anger; third, he might immediately engage
in violent gymnastic exercises and thus consume all the motor-producing
elements mobilized by the anger and thus clarify his body.

In these premises we find our explanation of the origin and purpose
of laughter and crying, for since they consist almost wholly
of muscular exertion, they serve precisely such clarifying purposes
as would be served by the gymnastic exercises of an angry man.
As it seems to me, the muscular action of laughter clears the system
of the energizing substances which have been mobilized in various
parts of the body for the performance of other actions (Figs. 27
to 29). If this be true, the first question that presents itself is,
Why is the respiratory system utilized for such a clarifying purpose?
Why do we not laugh with our feet and hands as well?
Were laughter expressed with the hands, the monkey might fall
from the tree and, if by the feet, man might fall to the ground.
He would at least be ataxic.  In fact, laughter has the great
advantage of utilizing a group of powerful muscles which can be
readily spared without seriously interfering with the maintenance
of posture.  Laughter, however, is only one form of muscular action
which may consume the fuel thrown into the blood by excitation.
That these products of excitation are often consumed by other motor
acts than laughter is frequently seen in public meetings when
the stamping of feet and the clapping of hands in applause gives
relief to the excitation (Fig. 30). Why the noise of laughter?
In order that the products of excitation may be quickly and
completely consumed, the powerful group of expiratory muscles must
have some resistance against which they can exert themselves strongly
and at the same time provide for adequate respiratory exchange.
The intermittent closure of the epiglottis serves this purpose admirably,
just as the horizontal bars afford the resistance against which muscles
may be exercised.  The facial muscles are not in use for other purposes,
hence their contractions will consume a little of the fuel.
An audience excited by the words of an impassioned speaker undergoes
a body-wide stimulation for action, all of which may be eliminated
by laughter or by applause (Fig. 31).

Let us test this hypothesis by some practical examples.
The first is an incident that accidentally occurred in our laboratory
during experiments on fear which were performed as follows:
A keen, snappy fox terrier was completely muzzled by winding a broad strip
of adhesive plaster around his jaw so as to include all but the nostrils.
When this aggressive little terrier and the rabbit found themselves
in close quarters each animal became completely governed by instinct;
the rabbit crouched in fear, while the terrier, with all the ancestral
assurance of seizing his prey, rushed, upon the rabbit, his muzzle
always glancing off and his attack ending in awkward failure.

This experiment was repeated many times and each time provoked
the serious-minded scientific visitors who witnessed it
to laughter.  Why?  Because the spectacle of a savage little terrier
rushing upon an innocent rabbit as if to mangle it integrated
the body of the onlooker with a strong desire to exert muscular
action to prevent the cruelty.  This integration caused a conversion
of the potential energy in the brain-cells into kinetic energy,
and there resulted a discharge into the blood-stream of activating
internal secretions for the purpose of producing muscular action.
Instantly and unexpectedly the danger passed and the preparation
for muscular action intended for use in the protection of the rabbit
was not needed.  This fuel was consumed by the neutral muscular
action of laughter, which thus afforded relief.

A common example of the same nature is that encountered on the street
when a pedestrian slips on a banana peel and, just as he is
about to tumble, recovers his equilibrium.  The onlookers secure
relief from the integration to run to his rescue by laughing.
On the other hand, should the same pedestrian fall and fracture
his skull the motor integration of the onlookers would be consumed
by rendering physical assistance--hence there would be no laughter.
In children almost any unexpected phenomenon, such as a sudden "booing"
from behind a door, is attended by laughter, and in like manner
the kinetic reaction produced by the innumerable threats of danger
which are suddenly averted, a breach of the conventions, a sudden
relief from acute nervous tension; a surprise--indeed, any excitant
to which there is no predetermined method of giving a physical response--
may be neutralized by the excitation of the mechanism of laughter.

In the same way the laughter excited by jokes may be explained.
An analysis of a joke shows that it is composed of two parts--
the first, in which is presented a subject that acts as a stimulus
to action, and the second, in which the story turns suddenly
so that the stimulus to action is unexpectedly withdrawn.
The subject matter of the joke affects each hearer according
to the type of stimuli that commonly excites that individual.
Hence it is that a joke may convulse one person while it bores another,
and so there are jokes of the classes, bankers' jokes, politicians' jokes,
the jokes of professional men, of the plebeian, of the artist, etc.
If the joke fails, the integration products of the excitation may
be used in physical resentment (Fig. 32).

Another type of laughter is that associated with the ticklish points
of certain parts of the body, the soles of the feet and certain
parts of the trunk and of the abdomen.  The excitation of the
ticklish receptors, like pain, compels self-defensive motor acts.
This response is of phylogenetic origin, and may be awakened only
by stimuli which are too light to be painful.  In this connection
it is of interest to note that a superficial, insect-like contact
with the skin rarely provokes laughter, and that the tickling
of the nasal, oral, and pulmonary tracts does not produce laughter.
The ticklish points that cause laughter are rather deeply placed,
and a certain type of physical contact is required to constitute
an adequate stimulus.  That is, the contact must arouse a phylogenetic
association with a physical struggle or with physical exertion.
In the foot, the adequate stimuli for laughter are such contacts
as resemble or suggest piercing by stones or rough objects.. The
intention of the one who tickles must be known; if his intention
be playful, laughter results, whereas if injury be intended,
then an effort toward escape or defense is excited, but no laughter.
If deep tickling of the ribs is known to be malicious, it will excite
physical resentment and not laughter.  Self-tickling rarely causes
laughter for the reason that auto-tickling can cause only a known
degree of stimulation, so that there results no excessive integration
which requires relief by the neutral muscular activity of laughter.
In fact, one never sees purposeful acts and laughter associated.
According to its severity, an isolated stimulus causes either
an action or laughter.  The ticklish points in our bodies were
probably developed as a means of defense against serious attacks
and of escape from injurious contacts.

Anger, fear, and grief are also strong excitants and, therefore,
are stimuli to motor activity.  It is obvious that whatever the excitant
the physico-chemical action of the brain and the ductless glands
cannot be reversed--the effect of the stimulus cannot be recalled,
therefore either a purposeful muscular act or a neutralizing act
must be performed or else the liberated energy must smoulder
in the various parts of the body.

It is on this hypothesis that the origin and the purpose of laughter
and crying may be understood.  Even a superficial analysis of the
phenomena of both laughter and crying show them to be without any
external motor purpose; the respiratory mechanism is intermittently
stimulated and inhibited; and the shoulder and arm muscles, indeed,
many muscles of the trunk and the extremities are, as far as any
external design is concerned, purposelessly contracted and released
until the kinetic energy mobilized by excitation is utilized.
During this time the facial expression gives the index to
the mental state.

Crying, like laughter, is always preceded by a stimulation
to some motor action which may or may not be performed
(Figs. 33 and 34). If a mother is anxiously watching the course
of a serious illness of her child and if, in caring for it, she is
stimulated to the utmost to perform motor acts, she will continue
in a state of motor tenseness until the child recovers or dies.
If relief is sudden, as in the crisis of pneumonia, and the mother
is not exhausted, she will easily laugh if tired, she may cry.
If death occurs, the stimulus to motor acts is suddenly
withdrawn and she then cries aloud, and performs many motor
acts as a result of the intense stimulation to motor activity
which is no longer needed in the physical care of her child.
With this clue we can find the explanation of many phenomena.  We can
understand why laughter and crying are so frequently interchangeable;
why they often blend and why either gives a sense of relief;
we can understand why either laughter or crying can come only
when the issue that causes the integration is determined; we can
understand the extraordinary tendency to laughter that discloses
the unspoken sentiments of love; we can understand the tears
of the woman when she receives a proposal of marriage from the man
she loves; we can understand why any averted circumstance,
such as a threatened breach of the conventions, which would have led
to embarrassment or humiliation, leads to a tendency to laughter;
and why the recital of heroic deeds by association leads to tears,
On the other hand, under the domination of acute diseases,
of acute fear, or of great exhaustion, there is usually neither
laughter nor crying because the nervous system is under the control
of a dominating influence as a result of which the body is so
exhausted that the excess of energy which alone can produce laughing
or crying is lacking.

A remarkable study of the modification of laughter and crying by disease
is found in that most interesting of diseases--exophthalmic goiter.
In this disease there is a low threshold to all stimuli.
That the very motor mechanism of which we have been speaking
is involved, is shown by an enormous increase in its activity.
There is also an increase in the size of certain at least of the
activating glands--the thyroid and the adrenals are enlarged and overactive
and the glycogen-producing function of the liver is stimulated.
The most striking phenomenon of this disease, however, is the remarkable
lowering of the brain thresholds to stimuli.  In other words,
in Graves' disease the nervous system and the activating glands--
the entire motor mechanism--are in an exalted state of activity.

If this be true, then these patients should exhibit behavior
precisely contrary to that of those suffering from acute infection,
that is, they should be constantly clearing their systems of
these superabundant energizing materials by crying or laughing,
and this is precisely what happens--the flood-gates of tears are open
much of the time in Graves' disease--a disease of the emotions.

We have already interpreted pain as a phenomenon of motor activity.
When pain does not lead to muscular activity it therefore frequently
leads to crying or to moaning, just as tickling, which is equally
an incentive to motor activity, results in laughter if it does
not find full expression in action.

From the foregoing we infer that pain, the intense motor response
to tickling, and emotional excitation are all primitive biologic
reactions for the good of the individual, and that all have
their origin in the operation of the great laws of evolution.
If to this inference we add the physiologic dictum that the nervous
system always acts as a whole, and that it can respond to but one
stimulus at a time, we can easily understand that while diverse
causes may integrate the nervous system for a specific action,
if the cause be suddenly removed, then the result of the
integration of the nervous system may be, not a specific action,
but an undesigned muscular action, such as crying or laughter.
Hence it is that laughter and crying may be evoked by diverse
exciting causes.  The intensity of the laughter or of the crying
depends upon the intensity of the stimulus and the dynamic state
of the individual.

The linking together of these apparently widely separated phenomena
by the simple law of the discharge of energy by association perhaps
explains the association of an abnormal tendency to tears with an
abnormally low threshold for pain (Fig. 36). In the neurasthenic,
tears and pain are produced with abnormal facility.  Hence it is that,
if a patient about to undergo a surgical operation is in a state of fear
and dread before the operation, the threshold to all stimuli is lowered,
and this lowered threshold will continue throughout the operation,
even under inhalation anesthesia, because the stimulus produced by
cutting sensitive tissue is transmitted to the brain just as readily
as if the patient were not anesthetized.  In like manner, the brain
may be sensitized by the administration of large doses of thyroid
extract prior to operation, the threshold to injury in such a case
continuing to be low to traumatic stimuli even under anesthesia.
Under the sensitizing influences of thyroid extract or of Graves'
disease the effect of an injury, of an operation, or of emotional
excitation is heightened.  The extent to which the threshold to pain
or to any other excitant is affected by Graves' disease is illustrated
by the almost fatal reaction which I once saw result from the mere
pricking with a hypodermic needle of a patient with this disease.
As the result of a visit from a friend, the pulse-rate of a victim of this
disease may increase twenty beats and his temperature rise markedly.
I have seen the mere suggestion of an operation produce collapse.
As the brain is thus remarkably sensitized in Graves' disease, we find
that in these patients laughter, crying, emotional disturbances,
and surgical shock are produced with remarkable facility.

I hope that even this admittedly crude and imperfect consideration
of this subject will suggest the possibility of establishing
a practical viewpoint as to the origin and purpose of pain,
of tickling, and of such expressions of emotion as laughter and crying,
and that it may help us to understand their significance in health
and in disease.



THE RELATION BETWEEN THE PHYSICAL STATE OF THE BRAIN-CELLS AND
BRAIN FUNCTIONS--EXPERIMENTAL AND CLINICAL[*]

[*] Address before The American Philosophical Society, April 18, 1913.


The brain in all animals (including man) is but the clearing-house
for reactions to environment, for animals are essentially motor
or neuromotor mechanisms, composed of many parts, it is true,
but integrated by the nervous system.  Throughout the phylogenetic history
of the race the stimuli of environment have driven this mechanism,
whose seat of power--the battery--is the brain.

Since all normal life depends upon the response of the brain
to the daily stimuli, we should expect in health, as well
as in disease, to find modifications of the functions and the
physical state of the component parts of this central battery--
the brain-cells. Although we must believe, then, that every
reaction to stimuli, however slight, produces a corresponding
change in the brain-cells, yet there are certain normal, that is,
non-diseased, conditions which produce especially striking changes.
The cell changes due to the emotions, for example, are so similar,
and in extreme conditions approach so closely to the changes produced
by disease, that it is impossible to say where the normal ceases
and the abnormal begins.

In view of the similarity of brain-cell changes it is not strange
that in the clinic as well as in daily life, we are confronted
constantly by outward manifestations which are so nearly
identical that the true underlying cause of the condition in
any individual case is too often overlooked or misunderstood.
In our laboratory experiments and in our clinical observations
we have found that exhaustion produced by intense emotion,
prolonged physical exertion, insomnia, intense fear, certain toxemias,
hemorrhage, and the condition commonly denominated surgical shock,
produce similar outward manifestations and identical brain-cell changes.

It is, therefore, the purpose of this paper to present the definite
results of laboratory researches which show certain relations
between alterations in brain functions and physical changes
in the brain-cells.

Fear.--Our experiments have shown that the brain-cell changes due
to fear may be divided into two stages:  First, that of hyperchromatism--
stimulation; second, that of hypochromatism--exhaustion (Figs. 5 and
13). Hyperchromatism was shown only in the presence of the activating
stimuli or within a very short time after they had been received.
This state gradually changed until the period of maximum exhaustion
was reached--about six hours later.  Then a process of reconstruction
began and continued until the normal state was again reached.

Fatigue.--Fatigue from overexertion produced in the brain-cells
like changes to those produced by fear, these changes being
proportional to the amount of exertion (Fig. 4). In the extreme
stage of exhaustion from this cause we found that the total
quantity of Nissl substance was enormously reduced.
When the exertion was too greatly prolonged, it took weeks or
months for the cells to be restored to their normal condition.
We have proved, therefore, that in exhaustion resulting from emotion
or from physical work a certain number of the brain-cells are
permanently lost.  This is the probable explanation of the fact
that an athlete or a race-horse trained to the point of highest
efficiency can reach his maximum record but once in his life.
Under certain conditions, however, it is possible that, though some
chromatin is forever lost, the remainder may be so remarkably developed
that for a time at least it will compensate for that which is gone.

Hemorrhage.--The loss of blood from any cause, if sufficient to reduce
the blood-pressure, will occasion a change in the brain-cells, provided
that the period of hypotension lasts for more than five minutes.
This time limit is a safeguard against permanent injury
from the temporary hypotension which causes one to faint.
If the hemorrhage be long continued and the blood-pressure be low,
there will be a permanent loss of some of the brain-cells. This
explains why an individual who has suffered from a prolonged
hemorrhage will never again be restored to his original powers.

Drugs.--According to their effect upon the brain-cells, drugs
may be divided into three classes:  First, those that stimulate
the brain-cells to increased activity, as strychnin (Fig. 37);
second, those that chemically destroy the brain-cells, as alcohol
and iodoform (Figs. 38 and 39); third, those that suspend the functions
of the cells without damaging them, as nitrous oxid, ether, morphin.
Our experiments have shown that the brain-cell changes induced
by drugs of the first class are precisely the same as the cycle
of changes produced by the emotions and by physical activity.
We have found that strychnin, according to the dosage, causes convulsions
ending in exhaustion and death; excitation followed by lassitude;
stimulation without notable after-results; or


{illust. caption = A, Section of Cerebellum of Normal Dog.  C, Section of
Cerebellum of Dog after Repeated Doses of Strychnin.  FIG.  37.--
BRAIN-CELLS SHOWING STAGE OF HYPERCHROMATISM FOLLOWED BY CHROMATOLYSIS
RESULTING FROM THE CONTINUATION OF THE STIMULUS.  (Camera lucida
drawings.)increased mental tone; while the brain-cells accurately
display these physiologic alterations in proportional hyperchromatism
in the active stages, and proportional chromatolysis in the stages
of reaction.  The biologic and therapeutic application of this fact
is as obvious as it is important.

In our experiments, alcohol in large and repeated dosage caused
marked morphologic changes in the brain-cells which went as far
even as the destruction of some of the cells (Fig. 39). Ether,
on the other hand, even after five hours of administration,
produced no observable destructive changes in the brain-cells.

The effect of iodoform was peculiarly interesting, as it was the only
drug that produced a rise of temperature.  Its observed effect upon
the brain-cells was that of wide-spread destruction.

Infections.--In every observation regarding the effect of pyogenic
infections on dogs and on man we found that they caused definite
and demonstrable lesions in certain cells of the nervous system,
the most marked changes being in the cortex and the cerebellum
(Fig. 40). For example, in fatal infections resulting from
bowel obstruction, in peritonitis, and in osteomyelitis, the real
lesion is in the brain-cells. We may, therefore, reasonably conclude
that the lassitude, the diminished mental power, the excitability,
irritability, restlessness, delirium, and unconsciousness which may
be associated with acute infections, are due to physical changes
in the brain-cells.

Graves' Disease.--In Graves' disease the brain-cells show marked
changes which are apparently the same as those produced by overwork,
by the emotions, and by strychnin.  In the postmortem examination
of one advanced case it was found that a large number of brain-cells
were disintegrated beyond the power of recuperation, even had
the patient lived.  This is undoubtedly the reason why a severe case
of exophthalmic goiter sustains a permanent loss of brain power.

Insomnia.--The brains of rabbits which had been kept awake for one
hundred hours showed precisely the same changes as those shown
in physical fatigue, strychnin poisoning, and exhaustion from
emotional stimulation.  Eight hours of continuous sleep restored
all the cells except those that had been completely exhausted.
This will explain the permanent ill effect of long-continued insomnia;
that is, long-continued insomnia permanently destroys a part
of the brain-cells just as do too great physical exertion,
certain drugs, emotional strain, exophthalmic goiter, and hemorrhage.
We found, however, that if, instead of natural sleep, the rabbits
were placed for the same number of hours under nitrous oxid anesthesia,
not only did the brain-cells recover from the physical deterioration,
but that 90 per cent.  of them became hyperchromatic.
This gives us a possible clue to the actual chemical effect of sleep.
For since nitrous oxid owes its anesthetic effect to its influence
upon oxidation, we may infer that sleep also retards the oxidation
of the cell contents.  If this be true, then it is probable
that inhalation anesthetics exert their peculiar influence upon
that portion of the brain through which sleep itself is produced.
If nitrous oxid anesthesia and sleep are chemically identical, then we
have a further clue to one of the primary mechanisms of life itself;
and as a practical corollary one might be able to produce artificial
sleep which would closely resemble normal sleep, but which would
have this advantage, that by using an anesthetic which interferes with
oxidation the brain-cells might be reconstructed after physical fatigue,
after emotional strain, or after the depression of disease.

In the case of the rabbit in which nitrous oxid was substituted
for sleep, the appearance of the brain-cells resembled that in
but one other group experimentally examined--the brain-cells
of hibernating woodchucks.

Insanity.--Our researches have shown that in the course of a fatal
disease and in fatal exhaustion, however produced, death does not
ensue until there is marked disorganization of the brain tissue.
In the progress of disease or exhaustion one may see in different
patients every outward manifestation of mental deterioration,
manifestations which, in a person who does not show any other sign of
physical disease, mark him as insane.  Take, for example, the progressive
mental state of a brilliant scholar suffering from typhoid fever.
On the first day of the gradual onset of the disease he would
notice that his mental power was below its maximum efficiency;
on the second he would notice a further deterioration, and so
the mental effect of his disease would progress until he would
find it impossible to express a thought or to make a deduction.
No one can be philanthropic with jaundice; no one suffering
from Graves' disease can be generous; no mental process is possible
in the course of the acute infectious diseases.  Just prior to death
from any cause every one is in a mental state which, if it could
be continued, would cause that individual to be judged insane.
If the delirium that occurs in the course of certain diseases
should be continued, the patient would be judged insane.
In severe cases of Graves' disease the patient is insane.
Individuals under overwhelming emotion may be temporarily insane.
Every clinician has seen great numbers of cases in which insanity
is a phase of a disease, of an injury, or of an emotion.
The stage of excitation in anesthesia is insanity.
The only difference between what is conventionally called insanity
and the fleeting insanity of the sick and the injured is that of time.
We may conclude, therefore, what must be the brain-picture of the person
who is permanently insane.  This _a priori_ reasoning is all that
is possible, since the study of the brain in the insane has thus far
been confined to the brains of those who have died of some disease.
And it is impossible to say which changes have been produced by the
fatal disease, and which by the condition which produced the insanity.
The only logical way by which to investigate the physical basis
of insanity would be to make use of the very rare opportunities
of studying the brains of insane persons who have died in accidents.

Our experiments have proved conclusively that whether we call a person
fatigued or diseased, the brain-cells undergo physical deterioration,
accompanied by loss of mental power (Figs. 40 to 43). Even to the minutest
detail we can show a direct relationship between the physical state
of the brain-cells and the mental power of the individual, that is,
the physical power of a person goes _pari passu_ with his mental power.
Indeed, it is impossible to conceive how any mental action,
however subtle, can occur without a corresponding change in the
brain-cells. It is possible now to measure only the evidences of
the effects on the brain-cells of gross and violent mental activity.
At some future time it will doubtless be possible so to refine
the technic of brain-cell examinations that more subtle changes
may be measured.  Nevertheless, with the means at our disposal
we have shown already that in all the conditions which we
have studied the cells of the cortex show the greatest changes,
and that loss of the higher mental functions invariably accompanies
the cell deterioration.




A MECHANISTIC VIEW OF PSYCHOLOGY[*]


[*] Address delivered before Sigma Xi, Case School
of Science, Cleveland, Ohio, May 27, 1913, and published
in _Science_, August 29, 1913.


Traditional religion, traditional medicine, and traditional psychology
have insisted upon the existence in man of a triune nature.
Three "ologies" have been developed for the study of each nature
as a separate entity--body, soul, and spirit--physiology, psychology,
theology; physician, psychologist, priest.  To the great minds
of each class, from the days of Aristotle and Hippocrates on,
there have come glimmerings of the truth that the phenomena
studied under these divisions were interrelated.  Always, however,
the conflict between votaries of these sciences has been sharp,
and the boundary lines between them have been constantly changing.
Since the great discoveries of Darwin, the zoologist, biologist,
and physiologist have joined hands, but still the soul-body-spirit
chaos has remained.  The physician has endeavored to fight the gross
maladies which have been the result of disordered conduct;
the psychologist has reasoned and experimented to find the laws
governing conduct; and the priest has endeavored by appeals to an
unknown god to reform conduct.

The great impulse to a deeper and keener study of man's relation,
not only to man, but to the whole animal creation, which was given
by Darwin, has opened the way to the study of man on a different basis.
Psychologists, physicians, and priests are now joining hands as never
before in the great world-wide movement for the betterment of man.
The new science of sociology is combining the functions of all three,
for priest, physician, and psychologist have come to see that man
is in large measure the product of his environment.

My thesis to-night, however, will go beyond this common agreement,
for I shall maintain, not that man is in _*large measure_ the product
of his environment, but that environment has been the actual CREATOR
of man; that the old division between body, soul, and spirit
is non-existent; that man is a unified mechanism responding in every
part to the adequate stimuli given it from without by the environment
of the present and from within by the environment of the past,
the record of which is stored in part in cells throughout
the mechanism, but especially in its central battery--the brain.
I postulate further that the human body mechanism is equipped, first,
for such conflict with environment as will tend to the preservation
of the individual; and, second, for the propagation of the species,
both of these functions when most efficiently carried out tending
to the upbuilding and perfection of the race.

Through the long ages of evolution the human mechanism has been
slowly developed by the constant changes and growth of its parts
which have resulted from its continual adaptation to its environment.
In some animals the protection from too rough contact with
surroundings was secured by the development of an outside armor;
in others noxious secretions served the purposes of defense,
but such devices as these were not suitable for the higher animals
nor for the diverse and important functions of the human race.
The safety of the higher animals and of man had to be preserved
by some mechanism by means of which they could become adapted
to a much wider and more complex environment, the dominance over
which alone gives them their right to be called "superior beings."
The mechanism by the progressive development of which living
beings have been able to react more and more effectually to their
environment is the central nervous system, which is seen in one
of its simplest forms in motor plants, such as the sensitive
plant and the Venus fly-trap, and in its highest development only
in the sanest, healthiest, happiest, and most useful men.

The essential function of the nervous system was primarily to secure
some form of motor activity, first as a means of securing food,
and later as a means of escaping from enemies and to promote procreation.
Activities for the preservation of the individual and of the species
were and are the only purposes for which the body energy is expended.
The central nervous system hag accordingly been developed for the purpose
of securing such motor activities as will best adapt the individuals
of a species for their self-preservative conflict with environment.

It is easy to appreciate that the simplest expressions of nerve response--
the reflexes--are motor in character, but it is difficult to understand
how such intangible reactions as love, hate, poetic fancy, or moral
inhibition can be also the result of the adaptation to environment
of a distinctively motor mechanism.  We expect, however, to prove
that so-called "psychic" states as well as the reflexes are products
of adaptation; that they occur automatically in response to adequate
stimuli in the environment; that, like the reflexes, they are
expressions of motor activity, which, although intangible and unseen,
in turn incite to activity the units of the motor mechanism of the body;
and finally, that any "psychic" condition results in a definite depletion
of the potential energy in the brain-cells which is proportionate
to the muscular exertion of which it is the representative.

That this nerve mechanism may effectively carry out its
twofold function, first, of self-adaptation to meet adequately
the increasingly complicated stimuli of environment; and second,
of adapting the motor mechanism to respond adequately to its demands,
there have been implanted in the body numerous nerve ceptors--
some for the transmission of stimuli harmful to the mechanism--
nociceptors some of a beneficial character--beneceptors; and still
others more highly specialized, which partake of the nature of both
bene- and nociceptors--the distance ceptors, or special senses.

A convincing proof that environment has been the creator
of man is seen in the absolute adaptation of the nociceptors
as manifested in their specific response to adequate stimuli,
and in their presence in only those parts of the body which throughout
the history of the race have been most exposed to harmful contacts.
We find they are most numerous in the face, the neck, the abdomen,
the hands, and the feet; while in the back they are few in number,
and within the bony cavities they are lacking.

Instances of the specific responses made by the nociceptors might be
multiplied indefinitely.  Sneezing, for example, is a specific response
made by the motor mechanism to stimulation of nociceptors in the nose,
while stimulation of the larynx does not produce a sneeze, but a cough;
stimulation of the nociceptors of the stomach does not produce cough,
but vomiting; stimulation of the nociceptors of the intestine
does not produce vomiting, but increased peristaltic action.
There are no nociceptors misplaced; none wasted; none that do not
make an adequate response to adequate stimulation.

Another most significant proof that the environment of the past
has been the creator of the man of to-day is seen in the fact
that man has added to his environment certain factors to which
adaptation has not as yet been made.  For example, heat is
a stimulus which has existed since the days of prehistoric man,
while the _x_-ray is a discovery of to-day; to heat, the nociceptors
produce an adequate response; to the _x_-ray there is no response.
There was no weapon in the prehistoric ages which could move at
the speed of a bullet from the modern rifle, therefore, while slow
penetration of the tissues produces great pain and muscular response,
there is no response to the swiftly moving bullet.

The response to contact stimuli then depends always on the presence
of nociceptors in the affected part of the body and to the type
of the contact.  Powerful response is made to crushing injury by
environmental forces; to such injuring contacts as resemble the impacts
of fighting; to such tearing injuries as resemble those made by teeth
and claws (Fig. 9). On the other hand, the sharp division of tissue
by cutting produces no adaptive response; indeed, one might imagine
that the body could be cut to pieces by a superlatively sharp knife
applied at tremendous speed without material adaptive response.

These examples indicate how the history of the phylogenetic experiences
of the human race may be learned by a study of the position
and the action of the nociceptors, just as truly as the study
of the arrangement and variations in the strata of the earth's
crust discloses to us geologic history.

These adaptive responses to stimuli are the result of the action
of the brain-cells, which are thus continually played upon by
the stimuli of environment.  The energy stored in the brain-cells
in turn activates the various organs and parts of the body.
If the environmental impacts are repeated with such frequency that
the brain-cells have no time for restoration between them, the energy
of the cells becomes exhausted and a condition of shock results.
Every action of the body may thus be analyzed into a stimulation
of ceptors, a consequent discharge of brain-cell energy,
and a final adaptive activation of the appropriate part.
Walking, running, and their modifications constitute an adaptation
of wonderful perfection, for, as Sherrington has shown,
the adaptation of locomotion consists of a series of reflexes--
ceptors in the joints, in the limb, and in the foot being stimulated
by variations in pressure.

As we have shown, the bene- and nociceptors orientate man to all
forms of physical contact--the former GUIDE HIM TO the acquisition
of food and to sexual contact; the latter DIRECT HIM FROM contacts
of a harmful nature.  The distance ceptors, on the other hand,
adapt man to his distant environment by means of communication
through unseen forces--ethereal vibrations produce sight; air waves
produce sound; microscopic particles of matter produce smell.
The advantage of the distance ceptors is that they allow time
for orientation, and because of this great advantage the majority
of man's actions are responses to their adequate stimuli.
As Sherrington has stated, the greater part of the brain has been
developed by means of stimuli received through the special senses,
especially through the light ceptors, the optic nerves.

We have just stated that by means of the distance ceptors animals
and man orientate themselves to their distant environment.
As a result of the stimulation of the special senses chase and escape
are effected, fight is conducted, food is secured, and mates are found.
It is obvious, therefore, that the distance ceptors are the primary
cause of continuous and exhausting expenditures of energy.
On the other hand, stimuli applied to contact ceptors lead to short,
quick discharges of nervous energy.  The child puts his hand
in the fire and there is an immediate and complete response
to the injuring contact; he sees a pot of jam on the pantry shelf
and a long train of continued activities are set in motion,
leading to the acquisition of the desired object.

The contact ceptors do not at all promote the expenditure of energy
in the chase or in fight, in the search for food or for mates.
Since the distance ceptors control these activities, one would expect to
find that they control also those organs whose function is the production
of energizing internal secretions.  Over these organs--the thyroid,
the adrenals, the hypophysis--the contact ceptors have no control.
Prolonged laboratory experimentation seems to prove this postulate.
According to our observations, no amount of physical trauma inflicted upon
animals will cause hyperthyroidism or increased adrenalin in the blood,
while fear and rage do produce hyperthyroidism and increased adrenalin
(Fig. 44) (Cannon). This is a statement of far-reaching importance
and is the key to an explanation of many chronic diseases--
diseases which are associated with the intense stimulation of
the distance ceptors in human relations.

Stimuli of the contact ceptors differ from stimuli of the distance
ceptors in still another important particular.  The adequacy of stimuli
of the contact ceptors depends upon their number and intensity,
while the adequacy of the stimuli of the distance ceptors depends
upon the EXPERIENCE of the species and of the individual.
That is, according to phylogeny and ontogeny this or that sound,
this or that smell, this or that sight, through association
recapitulates the experience of the species and of the individual--
awakens the phylogenetic and ontogenetic memory.  In other words, sights,
sounds, and odors are symbols which awaken phylogenetic association.
If a species has become adapted to make a specific response to a
certain object, then that response will occur automatically in an
individual of that species when he hears, sees, or smells that object.
Suppose, for example, that the shadow of a hawk were to fall
simultaneously on the eyes of a bird, a rabbit, a cow, and a boy.
That shadow would at once activate the rabbit and the bird to an
endeavor to escape, each in a specific manner according to its
phylogenetic adaptation; the cow would be indifferent and neutral;
while the boy, according to his personal experience or ontogeny,
might remain neutral, might watch the flight of the hawk with interest
or might try to shoot it.

Each phylogenetic and each ontogenetic experience by an indirect
method develops its own mechanism of adaptation in the brain;
and the brain threshold is raised or lowered to stimuli by
the strength and frequency of repetition of the experience.
Thus through the innumerable symbols supplied by environment the distance
ceptors drive this or that animal according to the type of brain
pattern and the particular state of threshold which has been developed
in that animal by its phylogenetic and ontogenetic experiences.
The brain pattern depends upon his phylogeny, the state of threshold
upon his ontogeny.  Each BRAIN PATTERN is created by some particular
element in the environment to which an adaptation has been made
for the good of the species.  The _*state of threshold_ depends
upon the effect made upon the individual by his personal contacts
with that particular element in his environment.  The presence
of that element produces in the individual an associative recall
of the adaptation of his species--that is, the brain pattern developed
by his phylogeny becomes energized to make a specific response.
The intensity of the response depends upon the state of threshold--
that is, upon the associative recall of the individual's
own experience--his ontogeny.

If the full history of the species and of the individual
could be known in every detail, then every detail of that
individual's conduct in health and disease could be predicted.
Reaction to environment is the basis of conduct, of moral standards,
of manners and conventions, of work and play, of love and hate,
of protection and murder, of governing and being governed, in fact,
of all the reactions between human beings--of the entire web of life.
To quote Sherrington once more:  "Environment drives the brain,
the brain drives the various organs of the body."

By what means are these adaptations made?  What is the mechanism through
which adequate responses are made to the stimuli received by the ceptors?
We postulate that in the brain there are innumerable patterns
each the mechanism for the performance of a single kind of action,
and that the brain-cells supply the energy--electric or otherwise--
by which the act is performed; that the energy stored in the brain-cells
is in some unknown manner released by the force which activates
the brain pattern; and that through an unknown property of these brain
patterns each stimulus causes such a change that the next stimulus
of the same kind passes with greater facility.

Each separate motor action presumably has its own mechanism--
brain pattern--which is activated by but one ceptor and by
that ceptor only when physical force of a certain intensity
and rate of motion is applied.  This is true both of the visible
contacts affecting the nociceptors and of the invisible contacts
by those intangible forces which affect the distance ceptors.
For example, each variation in speed of the light-producing
waves of ether causes a specific reaction in the brain.
For one speed of ether waves the reaction is the perception
of the color blue; for another, yellow; for another, violet.
Changes in the speed of air waves meet with specific response
in the brain patterns tuned to receive impressions through the
aural nerves, and so we distinguish differences in sound pitch.
If we can realize the infinite delicacy of the mechanisms adapted
to these infinitesimal variations in the speed and intensity of
invisible and intangible stimuli, it will not be difficult to conceive
the variations of brain patterns which render possible the specific
responses to the coarser contacts of visible environment.

Each brain pattern is adapted for but one type of motion,
and so the specific stimuli of the innumerable ceptors play
each upon its own brain pattern only.  In addition, each brain
pattern can react to stimuli applied only within certain limits.
Too bright a light blinds; too loud a sound deafens.  No mechanism
is adapted for waves of light above or below a certain rate of speed,
although this range varies in different individuals and in different
species according to the training of the individual and the need
of the species.

We have already referred to the fact that there is no receptive
mechanism adapted to the stimuli from the _x_-ray, from the
high-speed bullet, from electricity.  So, too, there are innumerable
forces in nature which can excite in man no adaptive response,
since there exist in man no brain patterns tuned to their waves,
as in the case of certain ethereal and radioactive forces.

On this mechanistic basis the emotions may be explained as activations
of the entire motor mechanism for fighting, for escaping, for copulating.
The sight of an enemy stimulates in the brain those patterns formed
by the previous experiences of the individual with that enemy, and also
the experiences of the race whenever an enemy had to be met and overcome.
Each of these many brain patterns in turn activates that part of
the body through which lies the path of its own adaptive response--
those parts including the special energizing or activating organs.
Laboratory experiments show that in an animal driven strongly
by emotion the following changes may be seen:  (1) A mobilization
of the energy-giving compound in the brain-cells, evidenced by a
primary increase of the Nissl substance and a later disappearance
of this substance and the deterioration of the cells (Figs. 5 and 13);
(2) increased output of adrenalin (Cannon), of thyroid secretion,
of glycogen, and an increase of the power of oxidation in the muscles;
(3) accelerated circulation and respiration with increased
body temperature; (4) altered metabolism.  All these are adaptations
to increase the motor efficiency of the mechanism.  In addition,
we find an inhibition of the functions of every organ and tissue that
consumes energy, but does not contribute directly to motor efficiency.
The mouth becomes dry; the gastric and pancreatic secretions are
lessened or are completely inhibited; peristaltic action stops.
The obvious purpose of all these activations and inhibitions is
to mass every atom of energy upon the muscles that are conducting
the defense or attack.

So strong is the influence of phylogenetic experience that though
an enemy to-day may not be met by actual physical attack,
yet the decks are cleared for action, as it were, and the weapons
made ready, the body as a result being shaken and exhausted.
The type of emotion is plainly declared by the activation
of the muscles which would be used if the appropriate physical
action were consummated.  In anger the teeth are set, the fists
are clenched, the posture is rigid; in fear the muscles collapse,
the joints tremble, and the running mechanism is activated
for flight; in sexual excitement the mimicry is as obvious.
The emotions, then, are the preparations for phylogenetic activities.
If the activities are consummated, the fuel--glycogen--and the activating
secretions from the thyroid, the adrenals, the hypophysis are consumed.
In the activation without action, these products must be eliminated
as waste products and so a heavy strain is put upon the organs
of elimination.  It is obvious that the body under emotion might be
clarified by active muscular exercise, but the subject of the emotion
is so strongly integrated thereby that it is difficult for him
to engage in diverting, clarifying exertion.  The person in anger
does not want to be saved from the ill effects of his own emotion;
he wants only to fight; the person in fear wants only to escape;
the person under sexual excitement wants only possession.

All the lesser emotions--worry, jealousy, envy, grief, disappointment,
expectation--all these influence the body in this manner, the consequences
depending upon the intensity of the emotion and its protraction.
Chronic emotional stimulation, therefore, may fatigue or exhaust
the brain and may cause cardiovascular disease, indigestion, Graves'
disease, diabetes, and insanity even.

The effect of the emotions upon the body mechanism may be compared
to that produced upon the mechanism of an automobile if its engines
are kept running at full speed while the machine is stationary.
The whole machine will be shaken and weakened, the batteries and weakest
parts being the first to become impaired and destroyed, the length
of usefulness of the automobile being correspondingly limited.

We have shown that the effects upon the body mechanism of the action
of the various ceptors is in relation to the response made by the brain
to the stimuli received.  What is this power of response on the part
of the brain but CONSCIOUSNESS?  If this is so, then consciousness
itself is a reaction to environment, and its intensity must vary
with the state of the brain and with the environmental stimuli.
If the brain-cells are in the state of highest efficiency, if their
energy has not been drawn upon, then consciousness is at its height;
if the brain is fatigued, that is, if the energy stored in the cells
has been exhausted to any degree, then the intensity of consciousness
is diminished.  So degrees of consciousness vary from the height
maintained by cells in full vigor through the stages of fatigue
to sleep, to the deeper unconsciousness secured by the administration
of inhalation anesthetics, to that complete unconsciousness
of the environment which is secured by blocking the advent to
the brain of all impressions from both distance and contact ceptors,
by the use of both local and inhalation anesthetics--the state
of anoci-association (Fig. 14).

Animals and man may be so exhausted as to be only semi-conscious.
While a brain perfectly refreshed by a long sleep cannot immediately
sleep again, the exhausted brain and the refreshed brain when subjected
to equal stimuli will rise to unequal heights of consciousness.
The nature of the physical basis of consciousness has been
sought in experiments on rabbits which were kept awake from
one hundred to one hundred and nine hours.  At the end of this
time they were in a state of extreme exhaustion and seemed
semi-conscious. If the wakefulness had been further prolonged,
this state of semi-consciousness would have steadily changed
until it culminated in the permanent unconsciousness of death.
An examination of the brain-cells of these animals showed physical
changes identical with those produced by exhaustion from other causes,
such as prolonged physical exertion or emotional strain (Figs. 45
and 46). After one hundred hours of wakefulness the rabbits were
allowed a long period of sleep.  All the brain-cells were restored
except those that had been in a state of complete exhaustion.
A single seance of sleep served to restore some of the cells,
but those which had undergone extreme changes required prolonged rest.
These experiments give us a definite physical basis for explaining
the cost to the body mechanism of maintaining the conscious state.
We have stated that the brain-cell changes produced by prolonged
consciousness are identical with those produced by physical exertion
and by emotional strain.  Rest, then, and especially sleep,
is needed to restore the physical state of the brain-cells which
have been impaired, and as the brain-cells constitute the central
battery of the body mechanism, their restoration is essential
for the maintenance of normal vitality.

In ordinary parlance, by consciousness we mean the activity
of that part of the brain in which associative memory resides,
but while associative memory is suspended the activities of the brain
as a whole are by no means suspended; the respiratory and circulatory
centers are active, as are those centers which maintain muscular tone.
This is shown by the muscular response to external stimuli made
by the normal person in sleep; by the occasional activation of motor
patterns which may break through into consciousness causing dreams;
and finally by the responses of the motor mechanism made to the injuring
stimuli of an operation on a patient under inhalation anesthesia only.

Direct proof of the mechanistic action of many of life's phenomena
is lacking, but the proof is definite and final of the part
that the brain-cells play in maintaining consciousness;
of the fact that the degree of consciousness and mental
efficiency depends upon the physical state of the brain-cells;
and finally that efficiency may be restored by sleep,
provided that exhaustion of the cells has not progressed too far.
In this greatest phenomenon of life, then, the mechanistic theory
is in harmony with the facts.

Perhaps no more convincing proof of our thesis that the body is
a mechanism developed and adapted to its purposes by environment
can be secured than by a study of that most constant manifestation
of consciousness--pain.

Like the other phenomena of life, pain was undoubtedly evolved
for a particular purpose--surely for the good of the individual.
Like fear and worry, it frequently is injurious.  What then may
be its purpose?

We postulate that pain is a result of contact ceptor stimulation
for the purpose of securing protective muscular activity.
This postulate applies to all kinds of pain, whatever their cause--
whether physical injury, pyogenic infection, the obstruction
of hollow viscera, childbirth, etc.

All forms of pain are associated with muscular action, and as in every
other stimulation of the ceptors, each kind of pain is specific
to the causative stimuli.  The child puts his hand in the fire;
physical injury pain results, and the appropriate muscular
response is elicited.  If pressure is prolonged on some parts
of the body, anemia of the parts may result, with a corresponding
discomfort or pain, requiring muscular action for relief.
When the rays of the sun strike directly upon the retina, light pain
causes an immediate protective action, so too in the evacuation
of the intestine and the urinary bladder as normal acts, and in
overcoming obstruction of these tracts, discomfort or pain compel
the required muscular actions.  This view of pain as a stimulation
to motor action explains why only certain types of infection are
associated with pain; namely, those types in which the infection
may be spread by muscular action or those in which the fixation
of parts by continued muscular rigidity is an advantage.
As a further remarkable proof of the marvelous adaptation
of the body mechanism to meet varying environmental conditions,
we find that just as nociceptors have been implanted in only those
parts of the body which have been subject to nocuous contacts,
so a type of infection which causes muscular action in one part
of the body may cause none when it attacks another.

This postulate gives us the key to the pain-muscular phenomena
of peritonitis, pleurisy, cystitis, cholecystitis, etc., as well as to
the pain-muscular phenomena in obstructions of the hollow viscera.
If pain is a part of a muscular response and occurs only
as a result of contact ceptor stimulation by physical injury,
infection, anemia, or obstruction, we may well inquire which part
of the nerve mechanism is the site of the phenomenon of pain.
Is it the nerve-ending, the nerve-trunk, or the brain?  That is,
is pain associated with the physical contact with the nerve-ending,
or with the physical act of transmission along the nerve-trunk,
or with the change of brain-cell substance by means of which
the motor-producing energy is released?

We postulate that the pain is associated with the discharge of energy
from the brain-cells. If this be true, then if every nociceptor in
the body were equally stimulated in such a manner that all the stimuli
should reach the brain-cells simultaneously, then the cells would
find themselves in equilibrium and no motor act would be performed.
But if all the pain nerve ceptors but one were equally stimulated,
and this one more strongly stimulated than the rest, then this
one would gain possession of the final common path--would cause
a muscular action and the sensation of pain.

It is well known that when a greater pain or stimulus is thrown
into competition with a lesser one, the lesser is submerged.
Of this fact the school-boy makes use when he initiates
the novice into the mystery of the painless pulling of hair.
The simultaneous but severe application of the boot to the blindfolded
victim takes complete but exclusive possession of the final common
path and the hair is painlessly plucked as a result of the triumph
of the boot stimulus over the pull on the hair in the struggle
for the final common path.

Persons who have survived a sudden, complete exposure to superheated steam,
or whose bodies have been enwrapped in flame, testify that they
have felt no pain.  As this absence of pain may be due to the fact
that the emotion of fear gained the final common path, to the exclusion
of all other stimuli, we are trying by experimentation to discover
the effects of simultaneous painful stimulation of all parts of the body.
The data already in hand, and the experiments now in progress,
in which anesthetized animals are subjected to powerful stimuli
applied to certain parts of the body only, or simultaneously to
all parts of the body, lead us to believe that in the former case
the brain-cells become stimulated or hyperchromatic, while in the latter
case no brain-cell changes occur.  We believe that our experiments
will prove that an equal and simultaneous stimulation of all parts
of the body leaves the brain-cells in a state of equilibrium.
Our theory of pain will then be well sustained, not only by common
observation, but by experimental proof, and so the mechanistic view
will be found in complete harmony with another important reaction.

We have stated that when a number of contact stimuli act simultaneously,
the strongest stimulus will gain possession of the final common path--
the path of action.  When, however, stimuli of the distance ceptors
compete with stimuli of the contact ceptors, the contact-ceptor
stimuli often secure the common path, not because they are stronger
or more important, but because they are immediate and urgent.
In many instances, however, the distance-ceptor stimuli are strong,
have the advantage of a lowered threshold, and therefore compete
successfully with the immediate and present stimuli of the
contact ceptors.  In such cases we have the interesting phenomenon
of physical injury without resultant pain or muscular response.
The distance-ceptor stimuli which may thus triumph over even powerful
contact-ceptor stimuli are those causing strong emotions--as great
anger in fighting; great fear in a battle; intense sexual excitement.
Dr. Livingstone has testified to his complete unconsciousness
to pain during his struggle with a lion; although he was torn
by teeth and claws, his fear overcame all other impressions.
By frequently repeated stimulation the Dervish secures a low
threshold to the emotions caused by the thought of God or the devil,
and his emotional excitement is increased by the presence of others
under the same stimulation; emotion, therefore, secures the final
common path and he is unconscious of pain when he lashes, cuts,
and bruises his body.  The phenomena of hysteria may be explained
on this basis, as may the unconsciousness of passing events
in a person in the midst of a great and overwhelming grief.
By constant practice the student may secure the final common path for
such impressions as are derived from the stimuli offered by the subject
of his study, and so he will be oblivious of his surroundings.
Concentration is but another name for a final common path secured
by the repetition and summation of certain stimuli.

If our premises are sustained, then we can recognize in man no will,
no ego, no possibility for spontaneous action, for every action must
be a response to the stimuli of contact or distance ceptors, or to their
recall through associative memory.  Memory is awakened by symbols which
represent any of the objects or forces associated with the act recalled.
Spoken and written words, pictures, sounds, may stimulate the brain
patterns formed by previous stimulation of the distance ceptors;
while touch, pain, temperature, pressure, may recall previous
contact-ceptor stimuli.  Memory depends in part upon the adequacy
of the symbol, and in part upon the state of the threshold.
If one has ever been attacked by a snake, the threshold to any
symbol which could recall that attack would be low; the later
recall of anything associated with the bite or its results would
produce in memory a recapitulation of the whole scene, while even
harmless snakes would thereafter be greeted with a shudder.
On the other hand, in a child the threshold is low to the desire
for the possession of any new and strange object; in a child,
therefore, to whom a snake is merely an unusual and fascinating object,
there is aroused only curiosity and the desire for the possession
of a new plaything.

If we are to attribute to man the possession of a governing
attribute not possessed by other parts of the animal creation,
where are we to draw the boundary line, and say "here the ego--
the will--the reason--emerges"? What attribute, after all, has man
which in its ultimate analysis is not possessed by the lowest
animals or by the vegetable creation, even?  From the ameba,
on through all the stages of animal existence, every action is
but a response to an adequate stimulus; and as a result of adequate
stimuli each step has been taken toward the higher and more
intricate mechanisms which play the higher and more intricate parts
in the great scheme of nature.

The Venus fly-trap responds to as delicate a stimulus as do
any of the contact ceptors of animals, and the motor activity
resulting from the stimulus is as complex.  To an insect-like touch
the plant responds; to a rough contact there is no response; that is,
the motor mechanism of the plant has become attuned to only such
stimuli as simulate the contact of those insects which form its diet.
It catches flies, eats and digests them, and ejects the refuse
(Fig. 47). The ameba does no less.  The frog does no more,
excepting that in its place in creation a few more reactions are
required for its sustenance and for the propagation of its species.
Man does no more, excepting that in man's manifold relations
there are innumerable stimuli, for meeting which adequately,
innumerable mechanisms have been evolved.  The motor mechanism
of the fly-trap is perfectly adapted to its purpose.
The motor mechanism of man is adapted to its manifold uses,
and as new environmental influences surround him, we must believe
that new adaptations of the mechanism will be evolved to meet
the new conditions.

Is not this conception of man's activities infinitely more wonderful,
and infinitely more comprehensible than is the conception that his
activities may be accounted for by the existence of an unknown,
unimaginable, and intangible force called "mind" or "soul"?

We have already shown how the nerve mechanism is so well adapted
to the innumerable stimuli of environment that it can accurately
transmit and distinguish between the infinite variations of speed
in the ether waves producing light, and the air waves producing sound.
Each rate of vibration energizes only the mechanism which has
been attuned to it.  With marvelous accuracy the light and sound
waves gain access to the nerve tissue and are finally interpreted
in terms of motor responses, each by the brain pattern attuned
to that particular speed and intensity.  So stimuli and resultant
actions multiplied by the total number of the motor patterns
in the brain of man give us the sum total of his life's activities--
they constitute his life.

As in evolutionary history the permanence of an adaptation of the body
mechanism depends upon its value in the preservation of the life
of the individual and upon its power to increase the value of
the individual to the race, so the importance and truth of these
postulates and theories may well be judged on the same basis.

The fundamental instincts of all living matter are self-preservation
and the propagation of the species.  The instinct for self-preservation
causes a plant to turn away from cold and damaging winds toward
the life-giving sun; the inert mussel to withdraw within its shell;
the insect to take flight; the animal to fight or to flee; and man
to procure food that he may oppose starvation, to shelter himself
and to provide clothes that he may avoid the dangers of excessive
cold and heat, to combat death from disease by seeking medical aid,
to avoid destruction by man or brute by fight or by flight.
The instinct to propagate the species leads brute man by crude methods,
and cultured man by methods more refined, to put out of his way sex
rivals so that his own life may be continued through offspring.
The life of the species is further assured by the protective
action exercised over the young by the adults of the species.
As soon as the youngest offspring is able successfully to carry on his
own struggle with environment there is no longer need for the parent,
and the parent enters therefore the stage of disintegration.
The average length of life in any species is the sum of the years
of immaturity, plus the years of female fertility, plus the adolescent
years of the offspring.

The stimuli resulting from these two dominant instincts are now
so overpowering as compared with all other environmental stimuli
that the mere possession of adequate knowledge of the damaging effects
of certain actions as compared with the saving effects of others will
(other things being equal) lead the individual to choose the right,--
the self- and species-preservative course of action, instead of the wrong,--
the self- and species-destructive course of action.

The dissemination of the knowledge of the far-reaching
deleterious effects of protracted emotional strain, of overwork,
and of worry will automatically raise man's threshold to
the damaging activating stimuli causing the strong emotions,
and will cause him to avoid dangerous strains of every kind.
The individual thus protected will therefore rise to a plane
of poise and efficiency far above that of his uncontrolled fellows,
and by so much will his efficiency, health, and happiness be augmented.

A full acceptance of this theory cannot fail to produce in those
in whose charge rests the welfare of the young, an overwhelming
desire to surround children with those environmental stimuli only
which will tend to their highest ultimate welfare.

Such is the stimulating force of tradition that many who
have been educated under the tenets of traditional beliefs
will oppose these hypotheses--even violently, it may be.
So they have opposed them; so they opposed Darwin; so they
have opposed all new and apparently revolutionary doctrines.
Yet these persons themselves are by their very actions proving
the efficiency of the vital principles which we have enunciated.
What is the whole social welfare movement but a recognition
on the part of municipalities, educational boards, and religious
organizations of the fact that the future welfare of the race
depends upon the administration to the young of forceful
uplifting environmental stimuli?

There are now, as there were in Darwin's day, many who feel that man
is degraded from his high estate by the conception that he is not
a reasoning, willing being, the result of a special creation.
But one may wonder indeed what conception of the origin of man can
be more wonderful or more inspiring than the belief that he has
been slowly evolved through the ages, and that all creatures
have had a part in his development; that each form of life has
contributed and is contributing still to his present welfare
and to his future advancement.


Recapitulation

Psychology,--the science of the human soul and its relations,--
under the mechanistic theory of life, must receive a new definition.
It becomes a science of man's activities as determined by the
environmental stimuli of his phylogeny and of his ontogeny.

On this basis we postulate that throughout the history of the race nothing
has been lost, but that every experience of the race and of the individual
has been retained for the guidance of the individual and of the race;
that for the accomplishment of this end there has been evolved through
the ages a nerve mechanism of such infinite delicacy and precision
that in some unknown manner it can register permanently within
itself every impression received in the phylogenetic and ontogenetic
experience of the individual; that each of these nerve mechanisms
or brain patterns has its own connection with the external world,
and that each is attuned to receive impressions of but one kind,
as in the apparatus of wireless telegraphy each instrument can
receive and interpret waves of a certain rate of intensity only;
that thought, will, ego, personality, perception, imagination,
reason, emotion, choice, memory, are to be interpreted in terms
of these brain patterns; that these so-called phenomena of human
life depend upon the stimuli which can secure the final common path,
this in turn having been determined by the frequency and the strength
of the environmental stimuli of the past and of the present.

Finally, as for life's origin and life's ultimate end,
we are content to say that they are unknown, perhaps unknowable.
We know only that living matter, like lifeless matter, has its own
place in the cosmic processes; that the gigantic forces which operated
to produce a world upon which life could exist, as a logical sequence,
when the time was ripe, evolved life; and finally that these cosmic
forces are still active, though none can tell what worlds and what
races may be the result of their coming activities.




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