darwin and modern science-第134节

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　voluntarily　performed　for　a　definite　object；namely；　to　escape　some　danger；　to　relieve　some　distress；　or　to　gratify　some　desire。〃　　（Ibid。　pages　373；　374。）

〃Our　second　principle　is　that　of　antithesis。　　The　habit　of　voluntarily　performing　opposite　movements　under　opposite　impulses　has　become　firmly　established　in　us　by　the　practice　of　our　whole　lives。　　Hence；　if　certain　actions　have　been　regularly　performed；　in　accordance　with　our　first　principle；　under　a　certain　frame　of　mind；　there　will　be　a　strong　and　involuntary　tendency　to　the　performance　of　directly　opposite　actions；　whether　or　not　these　are　of　any　use；　under　the　excitement　of　an　opposite　frame　of　mind。〃　　（〃Expression　of　the　Emotions〃；　page　368。）　　This　principle　of　antithesis　has　not　been　widely　accepted。　　Nor　is　Darwin's　own　position　easy　to　grasp。

〃Our　third　principle；〃　he　says　（Ibid。　page　369。）；　〃is　the　direct　action　of　the　excited　nervous　system　on　the　body；　independently　of　the　will；　and　independently；　in　large　part；　of　habit。　　Experience　shows　that　nerve…force　is　generated　and　set　free　whenever　the　cerebro…spinal　system　is　excited。　　The　direction　which　this　nerve…force　follows　is　necessarily　determined　by　the　lines　of　connection　between　the　nerve…cells；　with　each　other　and　with　various　parts　of　the　body。〃

Lack　of　space　prevents　our　following　up　the　details　of　Darwin's　treatment　of　expression。　　Whether　we　accept　or　do　not　accept　his　three　principles　of　explanation　we　must　regard　his　work　as　a　masterpiece　of　descriptive　analysis；　packed　full　of　observations　possessing　lasting　value。　　For　a　further　development　of　the　subject　it　is　essential　that　the　instinctive　factors　in　expression　should　be　more　fully　distinguished　from　those　which　are　individually　acquireda　difficult　taskand　that　the　instinctive　factors　should　be　rediscussed　in　the　light　of　modern　doctrines　of　heredity；　with　a　view　to　determining　whether　Lamarckian　inheritance；　on　which　Darwin　so　largely　relied；　is　necessary　for　an　interpretation　of　the　facts。

The　whole　subject　as　Darwin　realised　is　very　complex。　　Even　the　term　〃expression〃　has　a　certain　amount　of　ambiguity。　　When　the　emotion　is　in　full　flood　the　animal　fights；　flees；　or　faints。　　Is　this　full…tide　effect　to　be　regarded　as　expression；　or　are　we　to　restrict　the　term　to　the　premonitory　or　residual　effectsthe　bared　canine　when　the　fighting　mood　is　being　roused；　the　ruffled　fur　when　reminiscent　representations　of　the　object　inducing　anger　cross　the　mind？　　Broadly　considered　both　should　be　included。　　The　activity　of　premonitory　expression　as　a　means　of　communication　was　recognised　by　Darwin；　he　might；　perhaps；　have　emphasised　it　more　strongly　in　dealing　with　the　lower　animals。　　Man　so　largely　relies　on　a　special　means　of　communication；　that　of　language；　that　he　sometimes　fails　to　realise　that　for　animals　with　their　keen　powers　of　perception；　and　dependent　as　they　are　on　such　means　of　communication；　the　more　strictly　biological　means　of　expression　are　full　of　subtle　suggestiveness。　　Many　modes　of　expression；　otherwise　useless；　are　signs　of　behaviour　that　may　be　anticipated；signs　which　stimulate　the　appropriate　attitude　of　response。　　This　would　not；　however；　serve　to　account　for　the　utility　of　the　organic　accompanimentsheart…affection；　respiratory　changes；　vaso…motor　effects　and　so　forth；　together　with　heightened　muscular　tone；on　all　of　which　Darwin　lays　stress　（〃Expression　of　the　Emotions〃；　pages　65　ff。）　under　his　third　principle。　　The　biological　value　of　all　this　is；　however；　of　great　importance；　though　Darwin　was　hardly　in　a　position　to　take　it　fully　into　account。

Having　regard　to　the　instinctive　and　hereditary　factors　of　emotional　expression　we　may　ask　whether　Darwin's　third　principle　does　not　alone　suffice　as　an　explanation。　　Whether　we　admit　or　reject　Lamarckian　inheritance　it　would　appear　that　all　hereditary　expression　must　be　due　to　pre…established　connections　within　the　central　nervous　system　and　to　a　transmitted　provision　for　coordinated　response　under　the　appropriate　stimulation。　　If　this　be　so；　Darwin's　first　and　second　principles　are　subordinate　and　ancillary　to　the　third；　an　expression；　so　far　as　it　is　instinctive　or　hereditary；　being　〃the　direct　result　of　the　constitution　of　the　nervous　system。〃

Darwin　accepted　the　emotions　themselves　as　hereditary　or　acquired　states　of　mind　and　devoted　his　attention　to　their　expression。　　But　these　emotions　themselves　are　genetic　products　and　as　such　dependent　on　organic　conditions。　　It　remained；　therefore；　for　psychologists　who　accepted　evolution　and　sought　to　build　on　biological　foundations　to　trace　the　genesis　of　these　modes　of　animal　and　human　experience。　　The　subject　has　been　independently　developed　by　Professors　Lange　and　James　（Cf。　William　James；　〃Principles　of　Psychology〃；　Vol。　II。　Chap。　XXV；　London；　1890。）；　and　some　modification　of　their　view　is　regarded　by　many　evolutionists　as　affording　the　best　explanation　of　the　facts。　　We　must　fix　our　attention　on　the　lower　emotions；　such　as　anger　or　fear；　and　on　their　first　occurrence　in　the　life　of　the　individual　organism。　　It　is　a　matter　of　observation　that　if　a　group　of　young　birds　which　have　been　hatched　in　an　incubator　are　frightened　by　an　appropriate　presentation；　auditory　or　visual；　they　instinctively　respond　in　special　ways。　　If　we　speak　of　this　response　as　the　expression；　we　find　that　there　are　many　factors。　　There　are　certain　visible　modes　of　behaviour；　crouching　at　once；　scattering　and　then　crouching；　remaining　motionless；　the　braced　muscles　sustaining　an　attitude　of　arrest；　and　so　forth。　　There　are　also　certain　visceral　or　organic　effects；　such　as　affections　of　the　heart　and　respiration。　　These　can　be　readily　observed　by　taking　the　young　bird　in　the　hand。　　Other　effects　cannot　be　readily　observed；　vaso…motor　changes；　affections　of　the　alimentary　canal；　the　skin　and　so　forth。　　Now　the　essence　of　the　James…Lange　view；　as　applied　to　these　congenital　effects；　is　that　though　we　are　justified　in　speaking　of　them　as　effects　of　the　stimulation；　we　are　not　justified；　without　further　evidence；　in　speaking　of　them　as　effects　of　the　emotional　state。　　May　it　not　rather　be　that　the　emotion　as　a　primary　mode　of　experience　is　the　concomitant　of　the　net　result　of　the　organic　situationthe　initial　presentation；　the　instinctive　mode　of　behaviour；　the　visceral　disturbances？　　According　to　this　interpretation　the　primary　tissue　of　experience　of　the　emotional　order；　felt　as　an　unanalysed　complex；　is　generated　by　the　stimulation　of　the　sensorium　by　afferent　or　incoming　physiological　impulses　from　the　special　senses；　from　the　organs　concerned　in　the　responsive　behaviour；　from　the　viscera　and　vaso…motor　system。

Some　psychologists；　however；　contend　that　the　emotional　experience　is　generated　in　the　sensorium　prior　to；　and　not　subsequent　to；　the　behaviour…　response　and　the　visceral　disturbances。　　It　is　a　direct　and　not　an　indirect　outcome　of　the　presentation　to　the　special　senses。　　Be　this　as　it　may；　there　is　a　growing　tendency　to　bring　into　the　closest　possible　relation；　or　even　to　identify；　instinct　and　emotion　in　their　primary　genesis。　　The　central　core　of　all　such　interpretations　is　that　instinctive　behaviour　and　experience；　its　emotional　accompaniments；　and　its　expression；　are　but　different　aspects　of　the　outcome　of　the　same　organic　occurrences。　　Such　emotions　are；　therefore；　only　a　distinguishable　aspect　of　the　primary　tissue　of　experience　and　exhibit　a　like　differentiation。　　Here　again　a　biological　foundation　is　laid　for　a　psychological　doctrine　of　the　mental　development　of　the　individual。

The　intimate　relation　between　emotion　as　a　psychological　mode　of　experience　and　expression　as　a　group　of　organic　conditions　has　an　important　bearing　on　biological　interpretation。　　The　emotion；　as　the　psychological　accompaniment　of　orderly　disturbances　in　the　central　nervous　system　profoundly　influences　behaviour　and　often　renders　it　more　vigorous　and　more　effective。　　The　utility　of　the　emotions　in　the　struggle　for　existence　can；　therefore；　scarcely　be　over…estimated。　　Just　as　keenness　of　perception　has　survival…　value；　just　as　it　is　obviously　subject　to　variation；　just　as　it　must　be　enhanced　under　natural　selection；　whether　individually　acquired　increments　are　inherited　or　not；　and　just　as　its　value　lies　not　only　in　this　or　that　special　perceptive　act　but　in　its　importance　for　life　as　a　whole；　so　the　vigorous　effectiveness　of　activity　has　survival…value；　it　is　subject　to　variation；　it　must　be　enhanced　under　natural　selection；　and　its　importance　lies　not　only　in　particular　modes　of　behaviour　but　in　its　value　for　life　as　a　whole。　　If　emotion　and　its　expression　as　a　congenital　endowment　are　but　different　aspects　of　the　same　biological　occurrence；　and　if　this　is　a　powerful　supplement　to　vigour　effectiveness　and　persistency　of　behaviour；　it　must　on　Darwin's　principles　be　subject　to　natural　selection。

If　we　include　under　the　expression　of　the　emotions　not　only　the　premonitory　symptoms　of　the　initial　phases　of　the　organic　and　mental　state；　not　only　the　signs　or　conditions　of　half…tide　emotion；　but　the　full…tide　manifestation　of　an　emotion　which　dominates　the　situation；　we　are　naturally　led　on　to　the　consideration　of　many　of　the　phenomena　which　are　discussed　under　the　head　of　sexu