the origin and nature of emotions-第12节

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re　the　same。　　The　perception　of　danger　by　the　special　senses　in　the　sound　of　the　opening　gun　of　a　battle；　or　in　the　sight　of　a　venomous　snake；　is　phylogenetically　the　same　and　causes　the　same　effects　upon　the　entire　body　as　an　operation　under　anesthesia　or　a　physical　combat　in　that　each　drives　the　motor　mechanism。　The　use　of　local　anesthetics　in　the　operative　field　prevents　nerve…currents　from　the　seat　of　injury　from　reaching　the　brain　and　there　integrating　the　entire　body　for　a　self…defensive　struggle。　　The　result；　even　though　a　part　of　the　brain　is　asleep　and　the　muscles　paralyzed；　is　the　same　as　that　produced　by　the　interception　of　the　terrifying　sound　of　the　gun；　or　of　the　sight　of　the　dangerous　reptile；　since　the　stimulation　of　the　motor　mechanism　is　prevented。

By　both　the　positive　and　the　negative　evidence　we　are　forced　to　believe　that　the　emotions　are　primitive　instinctive　reactions　which　represent　ancestral　acts；　and　that　they　therefore　utilize　the　complicated　motor　mechanism　which　has　been　developed　by　the　forces　of　evolution　as　that　best　adapted　to　fit　the　individual　for　his　struggle　with　his　environment　or　for　procreation。

The　mechanism　by　which　the　motor　acts　are　performed　and　the　mechanism　by　which　the　emotions　are　expressed　are　one　and　the　same。　These　acts　in　their　infinite　complexity　are　suggested　by　association　phylogenetic　association。　　When　our　progenitors　came　in　contact　with　any　exciting　element　in　their　environment；　action　ensued　then　and　there。　　There　was　much　actionlittle　restraint　or　emotion。　Civilized　man　is　really　in　auto…captivity。　He　is　subjected　to　innumerable　stimulations；　but　custom　and　convention　frequently　prevent　physical　action。　　When　these　stimulations　are　sufficiently　strong　but　no　action　ensues；　the　reaction　constitutes　an　emotion。　A　phylogenetic　fight　is　anger；　a　phylogenetic　flight　is　fear；　a　phylogenetic　copulation　is　sexual　love；　and　so　one　finds　in　this　conception　an　underlying　principle　which　may　be　the　key　to　an　understanding　of　the　emotions　and　of　certain　diseases。



PAIN；　LAUGHTER；　AND　CRYING＇*＇

＇*＇　Address　delivered　before　the　John　Ashhurst；　Jr。。　Surgical　Society　of　the　University　of　Pennsylvania；　May　3；　1912。

PAIN


Pain；　like　other　phenomena；　was　probably　evolved　for　a　particular　purpose　surely　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　one　of　the　phenomena　which　result　from　a　stimulation　to　motor　action。　　When　a　barefoot　boy　steps　on　a　sharp　stone　it　is　important　that　the　injuring　contact　be　released　as　quickly　as　possible；　and　therefore　physical　injury　pain　results　and　impels　the　required　action。　　Anemia　of　the　soft　parts　at　the　points　of　pressure　results　from　prolonged　sitting　or　lying　in　one　position；　and　as　a　result　pain　compels　a　muscular　action　that　shifts　the　damaging　pressurethis　is　the　pain　of　anemia；　when　the　rays　of　the　blazing　sun　shine　directly　upon　the　retina；　pain　immediately　causes　a　protective　muscular　actionthe　lid　is　closed；　the　head　turns　awaythis　is　light　pain；　when　standing　too　close　to　a　blazing　fire　the　excessive　heat　causes　a　pain　which　results　in　the　protective　muscular　action　of　moving　awaythis　is　heat　pain；　when　the　urinary　bladder　is　acutely　overdistended　the　resultant　pain　induces　voluntary　as　well　as　involuntary　muscular　contraction　this　is　evacuation　pain；　associated　with　defecation　is　a　characteristic　warning　pain；　and　an　active　pain　which　induces　the　required　muscular　actionthis；　like　the　pain　accompanying　micturition；　is　an　evacuation　pain；　in　obstruction　of　the　urinary　passages　and　of　the　large　and　the　small　intestine　the　pain　is　exaggerated；　as　is　the　accompanying　muscular　contractionthis　is　a　pathologic　evacuation　pain；　when　the　fetus　reaches　full　term　and　labor　is　to　begin；　it　is　heralded　by　pain　which　is　associated　with　rhythmic　contractions　of　the　uterine　muscle；　later；　many　other　muscles　take　part　in　the　birth　and　pain　is　associated　with　all　these　muscular　contractionsthese　are　labor　pains；　when　a　foreign　body；　be　it　ever　so　small；　falls　upon　the　conjunctiva　or　cornea　there　results　what　is　perhaps　the　acutest　pain　known；　and　quick　and　active　muscular　action　followsthis　is　special　contact　pain。　　Special　pain　receptors　are　placed　in　certain　parts　of　the　nose；　the　pharynx；　and　the　larynx；　the　stimulation　of　which　causes　special　motor　acts；　such　as　sneezing；　hawking；　coughing。　　Curiously　vague　pains　are　associated　with　the　protective　motor　act　of　vomiting　and　with　the　sexual　motor　actsthese　may　be　termed　nausea　pains　and　pleasure　pains。　We　now　see；　therefore；　that　against　the　injurious　physical　contacts　of　environment；　against　heat　and　cold；　against　damaging　sunlight；　against　local　anemia　when　resting　or　sleeping；　the　body　is　protected　by　virtue　of　the　muscular　action　which　results　from　pain。　Then；　too；　for　the　emptying　of　the　pregnant　uterus；　for　the　evacuation　of　the　intestine　and　of　the　urinary　bladder　as　normal　acts；　and　for　the　overcoming　of　obstructions　in　these　tracts；　pain　compels　the　required　muscular　actions；　For　passing　gall…stones　and　urinary　calculi；　urgent　motor　stimuli　are　awakened　by　pain。　For　each　of　these　diversified　pains　the　consequent　muscular　action　is　specific　in　type；　distribution；　and　intensity。　　This　statement　is　so　commonplace　that　we　are　apt　to　miss　the　significance　and　the　wonder　of　it。　　It　is　probable　that　every　nerve…ending　in　the　skin　and　every　type　of　stimulation　represents　a　separate　motor　pattern；　the　adequate　stimulation　of　which　causes　always　the　same　response。

Let　us　pass　on　to　the　discussion　of　another　and　perhaps　even　more　interesting　type　of　pain；　that　associated　with　infection。　Not　all　kinds　of　infection　are　painful；　and　in　those　infections　that　may　be　associated　with　pain　there　is　pain　only　when　certain　regions　of　the　body　are　involved。　　Among　the　infections　that　are　not　associated　with　pain　are　scarlet　fever；　typhoid　fever；　measles；　malaria；　whooping…cough；　typhus　fever；　and　syphilis　in　its　early　stages。　The　infections　that　are　usually；　though　not　always；　associated　with　pain　are　the　pyogenic　infections。　　The　pyogenic　infections　and　the　exanthemata　constitute　the　great　majority　of　infections　and　are　the　basis　of　the　discussion　which　follows。

I　will　state　one　of　my　principal　conclusions　first；　_i。　e_。；　that　the　only　types　of　infection　that　are　associated　with　pain　are　those　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；　and；　further；　as　a　striking　corollary；　that　the　type　of　infection　that　may　cause　muscular　action　when　it　attacks　one　region　of　the　body　may　cause　no　such　action　when　it　attacks　another　region。

The　primary；　and　perhaps　the　most　striking；　difference　between　the　painless　exanthemata　and　the　painful　pyogenic　infections　is　that　in　the　case　of　the　exanthemata　the　protective　response　of　the　body　is　a　chemical　one；the　formation　of　antibodies　in　the　blood；　which　usually　produce　permanent　immunity；while　the　response　to　the　pyogenic　infections　is　largely　phagocytic。　　In　the　pyogenic　infections；　in　order　to　protect　the　remainder　of　the　body；　which；　of　course；　enjoys　no　immunity；　every　possible　barrier　against　the　spread　of　the　infection　is　thrown　about　the　local　point　of　infection。　How　are　these　barriers　formed？　　First；　lymph　is　poured　out；　then　the　part　is　fixed　by　the　continuous　contraction　of　the　neighboring　muscles　and　by　the　inhibition　of　those　muscles　that；　in　the　course　of　their　ordinary　function；　would　by　their　contractions　spread　the　infection。　Wherever　there　is　protective　muscular　rigidity　there　is　also　pain。　On　the　other　hand；　in　pyogenic　infections　in　the　substance　of　the　liver；　in　the　substance　of　the　kidney；　within　the　brain；　in　the　retroperitoneal　space；　in　the　lobes　of　the　lung；　in　the　chambers　of　the　heart　and　in　the　blood…vessels　of　the　chest　and　the　abdomen；　in　all　locations　in　which　muscular　contractions　can　in　no　way　assist　in　localizing　the　disease；　pyogenic　infections　produce　no　muscular　rigidity　and　no　pain。　　Apparently；　therefore；　only　those　infections　are　painful　which　are　associated　with　a　protective　muscular　contraction。　This　explains　why　tuberculosis　of　the　hip　is　painful；　while　tuberculosis　of　the　lung　is　painless。

There　is　a　third　type　of　pain　which　modifies　muscular　action　in　a　curious　way。　　We　have　already　stated　that　local　pain　serves　an　adaptive　purpose。　　In　this　light　let　us　now　consider　headache。　Headache　is　one　of　the　commonest　initiatory　symptoms　of　the　various　infections；　especially　of　those　infections　which　are　accompanied　by　no　local　pain　and　by　no　local　muscular　action。　In　peritonitis；　cholecystitis；　pleurisy；　arthritis；　appendicitis；　salpingitis；　child…birth；　in　obstructions　of　the　intestinal　and　the　genito…urinary　tract；　in　short；　in　those　acute　processes　in　which　the　local　symptoms　are　powerful　enough　to　govern　the　individual　as　a　whole；to　make　him　lie　down　and　keep　quiet；　refuse　food　and　possibly　reject　what　is　already　in　the　stomach；　in　all　these　conditions　there　is　rarely　a　headache；　but　in　the　diseases　in　which　local　pain　is　absent；　such　as　the　exanthemata；　typhoid　fever；　and　auto…intoxication；　which　have　no　dominating　local　disturba