the origin and nature of emotions-第5章

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nnected）　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　inte