In　a　large　number　of　cases；　as　with　the　salivary　and　lacrymal　glands；　intestinal　canal；　&c。；　the　power　of　attention　seems　to　rest；　either　chiefly；　or　as　some　physiologists　think；　exclusively；　on　the　vaso…motor　system　being　affected　in　such　a　manner　that　more　blood　is　allowed　to　flow　into　the　capillaries　of　the　part　in　question。　This　increased　action　of　the　capillaries　may　in　some　cases　be　combined　with　the　simultaneously　increased　activity　of　the　sensorium。
  The　manner　in　which　the　mind　affects　the　vasomotor　system　may　be　conceived　in　the　following　manner。　　When　we　actually　taste　sour　fruit；　an　impression　is　sent　through　the　gustatory　nerves　to　a　certain　part　of　the　sensorium；　this　transmits　nerve…force　to　the　vasomotor　centre；　which　consequently　allows　the　muscular　coats　of　the　small　arteries　that　permeate　the　salivary　glands　to　relax。　　Hence　more　blood　flows　into　these　glands；　and　they　secrete　a　copious　supply　of　saliva。　Now　it　does　not　seem　an　improbable　assumption；　that；　when　we　reflect　intently　on　a　sensation；　the　same　part　of　the　sensorium；　or　a　closely　connected　part　of　it；　is　brought　into　a　state　of　activity；　in　the　same　manner　as　when　we　actually　perceive　the　sensation。　If　so；　the　same　cells　in　the　brain　will　be　excited；　though；　perhaps；　in　a　less　degree；　by　vividly　thinking　about　a　sour　taste；　as　by　perceiving　it；　and　they　will　transmit　in　the　one　case；　as　in　the　other；　nerve…force　to　the　vaso…motor　centre　with　the　same　results。
  To　give　another；　and；　in　some　respects；　more　appropriate　illustration。　If　a　man　stands　before　a　hot　fire；　his　face　reddens。　　This　appears　to　be　due；　as　Mr。　Michael　Foster　informs　me；　in　part　to　the　local　action　of　the　heat；　and　in　part　to　a　reflex　action　from　the　vaso…motor　centres。＇46＇　In　this　latter　case；　the　heat　affects　the　nerves　of　the　face；　these　transmit　an　impression　to　the　sensory　cells　of　the　brain；　which　act　on　the　vaso…motor　centre；　and　this　reacts　on　the　small　arteries　of　the　face；　relaxing　them　and　allowing　them　to　become　filled　with　blood。　Here；　again；　it　seems　not　improbable　that　if　we　were　repeatedly　to　concentrate　with　great　earnestness　our　attention　on　the　recollection　of　our　heated　faces；　the　same　part　of　the　sensorium　which　gives　us　the　consciousness　of　actual　heat　would　be　in　some　slight　degree　stimulated；　and　would　in　consequence　tend　to　transmit　some　nerve…force　to　the　vaso…motor　centres；　so　as　to　relax　the　capillaries　of　the　face。　Now　as　men　during　endless　generations　have　had　their　attention　often　and　earnestly　directed　to　their　personal　appearance；　and　especially　to　their　faces；　any　incipient　tendency　in　the　facial　capillaries　to　be　thus　affected　will　have　become　in　the　course　of　time　greatly　strengthened　through　the　principles　just　referred　to；　namely；　nerve…force　passing　readily　along　accustomed　channels；　and　inherited　habit。　　Thus；　as　it　appears　to　me；　a　plausible　explanation　is　afforded　of　the　leading　phenomena　connected　with　the　act　of　blushing。
  _Recapitulation_。Men　and　women；　and　especially　the　young；　have　always　valued；　in　a　high　degree；　their　personal　appearance；　and　have　likewise　regarded　the　appearance　of　others。　　The　face　has　been　the　chief　object　of　attention；　though；　when　man　aboriginally　went　naked；　the　whole　surface　of　his　body　would　have　been　attended　to。　Our　self…attention　is　excited　almost　exclusively　by　the　opinion　of　others；　for　no　person　living　in　absolute　solitude　would　care　about　his　appearance。　Every　one　feels　blame　more　acutely　than　praise。　　Now；　whenever　we　know；　or　suppose；　that　others　are　depreciating　our　personal　appearance；　our　attention　is　strongly　drawn　towards　ourselves；　more　especially　to　our　faces。　　The　probable　effect　of　this　will　be；　as　has　just　been　explained；　to　excite　into　activity　that　part　of　the　sensorium；　which　receives　the　sensory　nerves　of　the　face；　and　this　will　react　through　the　vaso…motor　system　on　the　facial　capillaries。　By　frequent　reiteration　during　numberless　generations；　the　process　will　have　become　so　habitual；　in　association　with　the　belief　that　others　are　thinking　of　us；　that　even　a　suspicion　of　their　depreciation　suffices　to　relax　the　capillaries；　without　any　conscious　thought　about　our　faces。　With　some　sensitive　persons　it　is　enough　even　to　notice　their　dress　to　produce　the　same　effect。　　Through　the　force；　also；　of　association　and　inheritance　our　capillaries　are　relaxed；　whenever　we　know；　or　imagine；　that　any　one　is　blaming；　though　in　silence；　our　actions；　thoughts；　or　character；　and；　again；　when　we　are　highly　praised。
  ＇46＇　See；　also；　Mr。　Michael　Foster；　on　the　action　of　the　vaso…motor　system；　in　his　interesting　Lecture　before　the　royal　Institution；　as　translated　in　the　‘Revue　des　Cours　Scientifiques；'　Sept。　25；　1869；　p。　　683。
  On　this　hypothesis　we　can　understand　how　it　is　that　the　face　blushes　much　more　than　any　other　part　of　the　body；　though　the　whole　surface　is　somewhat　affected；　more　especially　with　the　races　which　still　go　nearly　naked。　　It　is　not　at　all　surprising　that　the　dark…coloured　races　should　blush；　though　no　change　of　colour　is　visible　in　their　skins。　From　the　principle　of　inheritance　it　is　not　surprising　that　persons　born　blind　should　blush。　　We　can　understand　why　the　young　are　much　more　affected　than　the　old；　and　women　more　than　men；　and　why　the　opposite　sexes　especially　excite　each　other's　blushes。　It　becomes　obvious　why　personal　remarks　should　be　particularly　liable　to　cause　blushing；　and　why　the　most　powerful　of　all　the　causes　is　shyness；　for　shyness　relates　to　the　presence　and　opinion　of　others；　and　the　shy　are　always　more　or　less　self…conscious。　With　respect　to　real　shame　from　moral　delinquencies；　we　can　perceive　why　it　is　not　guilt；　but　the　thought　that　others　think　us　guilty；　which　raises　a　blush。　A　man　reflecting　on　a　crime　committed　in　solitude；　and　stung　by　his　conscience；　does　not　blush；　yet　he　will　blush　under　the　vivid　recollection　of　a　detected　fault；　or　of　one　committed　in　the　presence　of　others；　the　degree　of　blushing　being　closely　related　to　the　feeling　of　regard　for　those　who　have　detected；　witnessed；　or　suspected　his　fault。
  Breaches　of　conventional　rules　of　conduct；　if　they　are　rigidly　insisted　on　by　our　equals　or　superiors；　often　cause　more　intense　blushes　even　than　a　detected　crime；　and　an　act　which　is　really　criminal；　if　not　blamed　by　our　equals；　hardly　raises　a　tinge　of　colour　on　our　cheeks。　Modesty　from　humility；　or　from　an　indelicacy；　excites　a　vivid　blush；　as　both　relate　to　the　judgment　or　fixed　customs　of　others。
  From　the　intimate　sympathy　which　exists　between　the　capillary　circulation　of　the　surface　of　the　head　and　of　the　brain；　whenever　there　is　intense　blushing；　there　will　be　some；　and　often　great；　confusion　of　mind。　This　is　frequently　accompanied　by　awkward　movements；　and　sometimes　by　the　involuntary　twitching　of　certain　muscles。
  As　blushing；　according　to　this　hypothesis；　is　an　indirect　result　of　attention；　originally　directed　to　our　personal　appearance；　that　is　to　the　surface　of　the　body；　and　more　especially　to　the　face；　we　can　understand　the　meaning　of　the　gestures　which　accompany　blushing　throughout　the　world。　　These　consist　in　hiding　the　face；　or　turning　it　towards　the　ground；　or　to　one　side。　The　eyes　are　generally　averted　or　are　restless；　for　to　look　at　the　man　who　causes　us　to　feel　shame　or　shyness；　immediately　brings　home　in　an　intolerable　manner　the　consciousness　that　his　gaze　is　directed　on　us。　Through　the　principle　of　associated　habit；　the　same　movements　of　the　face　and　eyes　are　practised；　and　can；　indeed；　hardly　be　avoided；　whenever　we　know　or　believe　that；　others　are　blaming；　or　too　strongly　praising；　our　moral　conduct。　　CHAPTER　XIV。
  CONCLUDING　REMARKS　AND　SUMMARY。
  The　three　leading　principles　which　have　determined　the　chief　movements　of　expressionTheir　inheritanceOn　the　part　which　the　will　and　intention　have　played　in　the　acquirement　of　various　expressions　The　instinctive　recognition　of　expressionThe　bearing　of　our　subject　on　the　specific　unity　of　the　races　of　manOn　the　successive　acquirement　of　various　expressions　by　the　progenitors　of　man　The　importance　of　expressionConclusion。
  I　HAVE　now　described；　to　the　best　of　my　ability；　the　chief　expressive　actions　in　man；　and　in　some　few　of　the　lower　animals。　I　have　also　attempted　to　explain　the　origin　or　development　of　these　actions　through　the　three　principles　given　in　the　first　chapter。　The　first　of　these　principles　is；　that　movements　which　are　serviceable　in　gratifying　some　desire；　or　in　relieving　some　sensation；　if　often　repeated；　become　so　habitual　that　they　are　performed；　whether　or　not　of　any　service；　whenever　the　same　desire　or　sensation　is　felt；　even　in　a　very　weak　degree。
  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。
  Our　third　principle　is　the　direct　action　of　the　excited　nervous　system　on　the　body；　independ