the origin and nature of emotions-第25节

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use　certain　diseases。　　For　example；　alterations　in　the　efficiency　of　the　cerebral　link　may　yield　neurasthenia；　mania；　dementia；　of　the　thyroid　link；　Graves'　disease；　myxedema；　of　the　adrenal　link；　Addison's　disease；　cardiovascular　disease。

This　introduction　may　serve　to　give　the　line　of　our　argument。　We　shall　now　consider　briefly　certain　salient　facts　which　relate　to　the　conversion　of　latent　into　kinetic　energy　as　an　adaptive　reaction。　The　experimental　data　are　so　many　that　they　will　later　be　published　in　a　monograph。

The　amount　of　latent　energy　which　may　be　converted　into　kinetic　energy　for　adaptive　ends　varies　in　different　species；　in　individuals　of　the　same　species；　in　the　same　individual　in　different　seasons；　in　the　life　cycle　of　growth；　reproduction　and　decay；　in　the　waking　and　sleeping　hours；　in　disease　and　in　activity。　We　shall　here　consider　briefly　the　reasons　for　some　of　those　variations　and　the　mechanisms　which　make　them　possible。


Biologic　Consideration　of　the　Adaptive　Variation　in　Amounts　of　Energy　Stored　in　Various　Animals

Energy　is　appropriated　from　the　physical　forces　of　nature　that　constitute　the　environment。　　This　energy　is　stored　in　the　body　in　quantities　in　excess　of　the　needs　of　the　moment。　In　some　animals　this　excess　storage　is　greater　than　in　other　animals。　Those　animals　whose　self…preservation　is　dependent　on　purely　mechanical　or　chemical　means　of　defensesuch　animals　as　crustaceans；　porcupines；　skunks　or　cobrashave　a　relatively　small　amount　of　convertible　（adaptive）　energy　stored　in　their　bodies。　On　the　contrary；　the　more　an　animal　is　dependent　on　its　muscular　activity　for　self…preservation；　the　more　surplus　available　（adaptive）　energy　there　is　stored　in　its　body。　　It　may　be　true　that　all　animals　have　approximately　an　equal　amount　per　kilo　of　chemical　energy　but　certainly　they　have　not　an　equal　amount　stored　in　a　form　which　is　available　for　immediate　conversion　for　adaptive　ends。　Adaptive　Variation　in　the　Rate　of　Energy　Discharge

What　chance　for　survival　would　a　skunk　have　without　odor；　a　cobra　without　venom；　a　turtle　without　carapace；　or　a　porcupine　shorn　of　its　barbs；　in　an　environment　of　powerful　and　hostile　carnivora？　And　yet　in　such　an　hostile　environment　many　unprotected　animals　survive　by　their　muscular　power　of　flight　alone。　　It　is　evident　that　the　provision　for　the　storage　of　〃adaptive〃　energy　is　not　the　only　evolved　characteristic　which　relates　to　the　energy　of　the　body。　The　more　the　self…preservation　of　the　animal　depends　on　motor　activity；　the　greater　is　the　range　of　variation　in　the　rate　of　discharge　of　energy。　The　rate　of　energy　discharge　is　especially　high　in　animals　evolved　along　the　line　of　hunter　and　hunted；　such　as　the　carnivora　and　the　herbivora　of　the　great　plains。


Influences　That　Cause　Variation　in　the　Rate　of　Output　of　Energy　in　the　Individual

Not　only　is　there　a　variation　in　the　rate　of　output　of　energy　among　various　species　of　animals；　but　one　finds　also　variations　in　the　rate　of　output　of　energy　among　individuals　of　the　same　species。　If　our　thesis　that　men　and　animals　are　mechanisms　responding　to　environmental　stimuli　be　correct；　and　further；　if　the　speed　of　energy　output　be　due　to　changes　in　the　activating　organs　as　a　result　of　adaptive　stimulation；　then　we　should　expect　to　find　physical　changes　in　the　activating　glands　during　the　cycles　of　increased　activation。　What　are　the　facts？　　We　know　that　most　animals　have　breeding　seasons　evolved　as　adaptations　to　the　food　supply　and　weather。　Hence　there　is　in　most　animals　a　mating　season　in　advance　of　the　season　of　maximum　food　supply　so　that　the　young　may　appear　at　the　period　when　food　is　most　abundant。　　In　the　springtime　most　birds　and　mammals　mate；　and　in　the　springtime　at　least　one　of　the　great　activating　glands　is　enlargedthe　thyroid　in　man　and　in　animals　shows　seasonal　enlargement。　　The　effect　of　the　increased　activity　is　seen　in　the　song；　the　courting；　the　fighting；　in　the　quickened　pulse；　and　in　a　slightly　raised　temperature。　　Even　more　activation　than　that　connected　with　the　season　is　seen　in　the　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　e