the origin and nature of emotions-第20节

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o　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　fuelglycogenand　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　emotionsworry；　jealousy；　envy；　grief；　disappointment；　expectationall　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　anestheticsthe　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　consciousnesspain。

Like　the　other　phenomena　of　life；　pain　was　undoubtedly　evolved　for　a　particular　purposesurely　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；　anem