the origin and nature of emotions-第20章

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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　entitybody；　soul；　and　spiritphysiology；　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　batterythe　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　reflexesare　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　characterbeneceptors；　and　still　others　more　highly　specialized；　which　partake　of　the　nature　of　both　bene…　and　nociceptorsthe　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　suc