the origin and nature of emotions-第23部分

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physical　state　of　mating；　when　the　thyroid　is　known　to　enlarge　materially；　though　this　increased　activity；　as　we　shall　show　later；　is　probably　no　greater　than　the　increased　activity　of　other　activating　glands。　In　the　mating　season　the　kinetic　activity　is　speeded　up；　in　short；　there　exists　a　statea　fleeting　stateof　mild　Graves'　disease。　In　the　early　stages　of　Graves'　disease；　before　the　destructive　phenomena　are　felt；　the　kinetic　speed　is　high；　and　life　is　on　a　sensuous　edge。　Not　only　is　there　a　seasonal　rhythm　to　the　rate　of　flow　of　energy；　but　there　is　a　diurnal　variationthe　ebb　is　at　night；　and　the　full　tide　in　the　daytime。　　This　observation　is　verified　by　the　experiments　which　show　that　certain　organs　in　the　kinetic　chain　are　histologically　exhausted；　the　depleted　cells　being　for　the　most　part　restored　by　sleep。

We　have　seen　that　there　are　variations　in　speed　in　different　species；　and　that　in　the　same　species　speed　varies　with　the　season　of　the　year　and　with　the　time　of　day。　　In　addition　there　are　variations　also　in　the　rate　of　discharge　of　energy　in　the　various　cycles　of　the　life　of　the　individual。　　The　young　are　evolved　at　high　speed　for　growth；　so　that　as　soon　as　possible　they　may　attain　to　their　own　power　of　self…defense；　they　must　adapt　themselves　to　innumerable　bacteria；　to　food；　and　to　all　the　elements　in　their　external　environment。　Against　their　gross　enemies　the　young　are　measurably　protected　by　their　parents；　but　the　parentsexcept　to　a　limited　extent　in　the　case　of　manare　unable　to　assist　in　the　protection　of　the　young　against　infectious　disease。

The　cycle　of　greatest　kinetic　energy　for　physiologic　ends　is　the　period　of　reproduction。　　In　the　female　especially　there　is　a　cycle　of　increased　activity　just　prior　to　her　development　into　the　procreative　state。　During　this　time　secondary　sexual　characters　are　developed　the　pelvis　expands；　the　ovaries　and　the　uterus　grow　rapidly；　the　mammary　glands　develop。　　Again　in　this　period　of　increasing　speed　in　the　expenditure　of　energy　we　find　the　thyroid；　the　adrenals；　and　the　hypophysis　also　in　rapid　growth。　Without　the　normal　development　of　the　ovary；　the　thyroid；　and　the　hypophysis；　neither　the　male　nor　the　female　can　develop　the　secondary　sexual　characters；　nor　do　they　develop　sexual　desire　nor　show　seasonal　cycles　of　activity；　nor　can　they　procreate。　The　secondary　sexual　characterssexual　desire；　fertilitymay　be　developed　at　will；　for　example；　by　feeding　thyroid　products　from　alien　species　to　the　individual　deprived　of　the　thyroid。

At　the　close　of　the　child…bearing　period　there　is　a　permanent　diminution　of　the　speed　of　energy　discharge；　for　energy　is　no　longer　needed　as　it　was　for　the　self…preservation　of　the　offspring　before　adolescence；　and　for　the　propagation　of　the　species　during　the　procreative　period。　　Unless　other　factors　intervene；　this　reduction　in　speed　is　progressive　until　senescent　death。　The　diminished　size　of　the　thyroid　of　the　aged　bears　testimony　to　the　part　the　activating　organs　bear　in　the　general　decline。

We　have　now　referred　to　variations　in　the　rate　of　discharge　of　energy　in　different　species；　in　individuals　of　the　same　species；　in　cycles　in　the　same　individualsuch　as　the　seasons　of　food　supply；　the　periods　of　wakefulness　and　of　sleep；　the　procreative　period；　and　we　have　spoken　of　those　variations　caused　artificially　by　thyroid　feeding；　thus　far　having　confined　our　discussion　to　the　conversion　for　adaptive　purposes　of　latent　into　kinetic　energy　in　muscular　and　in　procreative　action。　　We　shall　now　consider　the　conversion　of　latent　into　kinetic　energy　in　the　production　of　heat；＇*＇　and　endeavor　to　answer　the　questions　which　arise　at　once：　Is　there　one　mechanism　for　the　conversion　of　latent　energy　into　heat　and　another　mechanism　for　its　conversion　into　muscular　action？　What　is　the　adaptive　advantage　of　fever　in　infection？


＇*＇　We　use　the　terms　〃heat〃　and　〃muscular　action〃　in　the　popular　sense；　though　physicists　use　them　to　designate　one　and　the　same　kind　of　energy。

The　Purpose　and　the　Mechanism　of　Heat　Production　in　Infections

Vaughan　has　shown　that　the　presence　in　the　body　of　any　alien　protein　causes　an　increased　production　of　heat；　and　that　there　is　no　difference　between　the　production　of　fever　by　foreign　proteins　and　by　infections。　Before　the　day　of　the　hypodermic　needle　and　of　experimental　medicine；　the　foreign　proteins　found　in　the　body　outside　the　alimentary　tract　were　brought　in　by　invading　microorganisms。　　Such　organisms　interfered　with　and　destroyed　the　host。　　The　body；　therefore；　was　forced　to　evolve　a　means　of　protection　against　these　hostile　organisms。　The　increased　metabolism　and　fever　in　infection　might　operate　as　a　protection　in　two　waysthe　increased　fever；　by　interfering　with　bacterial　growth；　and　the　increased　metabolism；　by　breaking　up　the　bacteria。　　Bacteriologists　have　taught　us　that　bacteria　grow　best　at　the　normal　temperature　of　the　body；　hence　fever　must　interfere　with　bacterial　growth。　　With　each　rise　of　one　degree　centigrade　the　chemical　activity　of　the　body　is　increased　10　per　cent。　In　acute　infections　there　is　aversion　to　food　and　frequently　there　is　vomiting。　　In　fever；　then；　we　have　diminished　intake　of　energy；　but　an　increased　output　of　energyhence　the　available　potential　energy　in　the　body　is　rapidly　consumed。　　This　may　be　an　adaptation　for　the　purpose　of　breaking　up　the　foreign　protein　molecules　composing　the　bacteria。　　Thus　the　body　may　be　purified　by　a　chemical　combustion　so　furious　that　frequently　the　host　itself　is　destroyed。　The　problems　of　immunity　are　not　considered　here。

As　to　the　mechanism　which　produces　fever；　we　postulate　that　it　is　the　same　mechanism　as　that　which　produces　muscular　activity。　Muscular　activity　is　produced　by　the　conversion　of　latent　energy　into　motion；　and　fever　is　produced　largely　in　the　muscles　by　the　conversion　of　latent　energy　into　heat。　　We　should；　therefore；　find　similar　changes　in　the　brain；　the　adrenals；　the　thyroid；　and　the　liver；　whatever　may　be　the　purpose　of　the　conversion　of　energy　whether　for　running；　for　fighting；　for　the　expression　of　emotion；　or　for　combating　infection。

We　shall　first　present　experimental　and　clinical　evidence　which　tends　to　show　what　part　is　played　by　the　brain　in　the　production　of　both　muscular　and　febrile　action；　and　later　we　shall　discuss　the　parts　played　by　the　adrenals；　the　thyroid；　and　the　liver。　　Histologic　Changes　in　the　Brain…cells　in　Relation　to　the　Maintenance　of　Consciousness　and　to　the　Production　of　the　Emotions；　Muscular　Activity；　and　Fever

We　have　studied　the　brain…cells　in　human　cases　of　fever；　and　in　animals　after　prolonged　insomnia；　after　the　injection　of　the　toxins　of　gonococci；　of　streptococci；　of　staphylococci；　and　of　colon；　tetanus；　diphtheria；　and　typhoid　bacilli；　and　after　the　injection　of　foreign　proteins；　of　indol　and　skatol；　of　leucin；　and　of　peptones。　　We　have　studied　the　brains　of　animals　which　had　been　activated　in　varying　degrees　up　to　the　point　of　complete　exhaustion　by　running；　by　fighting；　by　rage　and　fear；　by　physical　injury；　and　by　the　injection　of　strychnin　（Figs。　2；　4；　5；　and　37）。　We　have　studied　the　brains　of　salmon　at　the　mouth　of　the　Columbia　River　and　at　its　headwater　（Fig。　55）；　the　brains　of　electric　fish；　the　storage　batteries　of　which　had　been　partially　discharged；　and　of　those　the　batteries　of　which　had　been　completely　discharged；　the　brains　of　woodchucks　in　hibernation　and　after　fighting；　the　brains　of　humans　who　had　died　from　anemia　resulting　from　hemorrhage；　from　acidosis；　from　eclampsia；　from　cancer　and　from　other　chronic　diseases　（Figs。　40　to　43；　56；　74；　and　75）。　We　have　studied　also　the　brains　of　animals　after　the　excision　of　the　adrenals；　of　the　pancreas；　and　of　the　liver　（Figs。　57　and　60）。

In　every　instance　the　loss　of　vitalitythat　is；　the　loss　of　the　normal　power　to　convert　potential　into　kinetic　energy　was　accompanied　by　physical　changes　in　the　brain…cells　（Figs。　45　and　46）。　The　converse　was　also　true；　that　is；　the　brain…cells　of　animals　with　normal　vital　power　showed　no　histologic　changes。　The　changes　in　the　brain…cells　were　identical　whatever　the　cause。　The　crucial　question　then　becomes：　　Are　these　constant　changes　in　the　brain…cells　the　result　of　work　done　by　the　brain…cells　in　running；　in　fighting；　in　emotion；　in　fever？　　In　other　words；　does　the　brain　perform　a　definite　role　in　the　conversion　of　latent　energy　into　fever　or　into　muscular　action；　or　are　the　brain…cell　changes　caused　by　the　chemical　products　of　metabolism？　　Happily；　this　crucial　question　was　definitely　answered　by　the　following　experiment：　The　circulations　of　two　dogs　were　crossed　in　such　a　manner　that　the　circulation　of　the　head　of　one　dog　was　anastomosed　with　the　circulation　of　the　body　of　another　dog；　and　vice　versa。　　A　cord　encircled　the　neck　of　each　so　firmly　that　the　anastomosing　circulation　was　blocked　（Fig。　58）。　If　the　brain…cell　changes　were　due　to　metabolic　products；　then　when　the　body　of　dog　〃A〃　was　injured；　the　brain　of　dog　〃A〃　would　be　normal　and　the　brain　of　dog　〃B〃　would　show　changes。　Our　experiments　showed　brain…cell　changes　in　the　brain　of　the　dog　injured　and　no　changes　in　the　brain　of　the　uninjured　dog。

The　injection　of　adrenalin　causes　striking　brain…cell　changes：　first；　a　hyperchromatism；　then　a　chromatolysis。　　Now　if　adrenalin　caused　these　changes　merely　as　a　metabolic　phenomenon　and　not　as　a　〃work〃　phenomenon；　then　the　injection　of　adrenalin　into　the　carotid　artery　of　a　crossed　circulation　dog　would　cause　no　change　in　its　circulation　and　its　respiration；　since　the　brain　thus　injected　is　in　exclusive　vascular　connection　with　the　body　of　another　dog。　In　our　experiment　the　blood…pressures　of　both　dogs　were　recorded　on　a　drum　when　adrenalin　was　injected　into　the　common　carotid。　The　adrenalin　caused　a　rise　in　blood…pressure；　an　increase　in　the　force　of　cardiac　contraction；　increase　in　respiration；　and　a　characteristic　adrenalin　rise　in　the　blood…pressure　of　both　dogs。　The　rise　was　seen　first　in　the　dog　whose　brain　alone　received　adrenalin　and　about　a　minute　later　in　the　dog　whose　body　alone　received　adrenalin　（Fig。　59）。　Histologic　examinations　of　the　brains　of　both　dogs　showed　marked　hyperchromatism　in　the　brain　receiving　adrenalin；　while　the　brain　receiving　no　adrenalin　showed　no　change。　Here　is　a　clear…c