the origin and nature of emotions-第22章

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tor　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　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　cons