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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 （exhaustionsurgical 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 instrumentan organthe 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