the expression of emotion in man and animals-第8部分

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A　start　from　a　sudden　noise；　when　the　stimulus　is　conveyed　through　the　auditory　nerves；　is　always　accompanied　in　grown…up　persons　by　the　winking　of　the　eyelids。＇13＇　I　observed；　however；　that　though　my　infants　started　at　sudden　sounds；　when　under　a　fortnight　old；　they　certainly　did　not　always　wink　their　eyes；　and　I　believe　never　did　so。　　The　start　of　an　older　infant　apparently　represents　a　vague　catching　hold　of　something　to　prevent　falling。　I　shook　a　pasteboard　box　close　before　the　eyes　of　one　of　my　infants；　when　114　days　old；　and　it　did　not　in　the　least　wink；　but　when　I　put　a　few　comfits　into　the　box；　holding　it　in　the　same　position　as　before；　and　rattled　them；　the　child　blinked　its　eyes　violently　every　time；　and　started　a　little。　It　was　obviously　impossible　that　a　carefully…guarded　infant　could　have　learnt　by　experience　that　a　rattling　sound　near　its　eyes　indicated　danger　to　them。　But　such　experience　will　have　been　slowly　gained　at　a　later　age　during　a　long　series　of　generations；　and　from　what　we　know　of　inheritance；　there　is　nothing　improbable　in　the　transmission　of　a　habit　to　the　offspring　at　an　earlier　age　than　that　at　which　it　was　first　acquired　by　the　parents。

From　the　foregoing　remarks　it　seems　probable　that　some　actions；　which　were　at　first　performed　consciously；　have　become　through　habit　and　association　converted　into　reflex　actions；　and　are　now　so　firmly　fixed　and　inherited；　that　they　are　performed；　even　when　not　of　the　least　use；＇14＇　as　often　as　the　same　causes　arise；　which　originally　excited　them　in　us　through　the　volition。　　In　such　cases　the　sensory　nerve…cells　excite　the　motor　cells；　without　first　communicating　with　those　cells　on　which　our　consciousness　and　volition　depend。　It　is　probable　that　sneezing　and　coughing　were　originally　acquired　by　the　habit　of　expelling；　as　violently　as　possible；　any　irritating　particle　from　the　sensitive　air…passages。　As　far　as　time　is　concerned；　there　has　been　more　than　enough　for　these　habits　to　have　become　innate　or　converted　into　reflex　actions；　for　they　are　common　to　most　or　all　of　the　higher　quadrupeds；　and　must　therefore　have　been　first　acquired　at　a　very　remote　period。　Why　the　act　of　clearing　the　throat　is　not　a　reflex　action；　and　has　to　be　learnt　by　our　children；　I　cannot　pretend　to　say；　but　we　can　see　why　blowing　the　nose　on　a　handkerchief　has　to　be　learnt。

＇13＇　Muller　remarks　（‘Elements　of　Physiology；'　Eng。　　tr。　　vol。　　ii。　　p。　　1311）　on　starting　being　always　accompanied　by　the　closure　of　the　eyelids。

＇14＇　Dr。　Maudsley　remarks　（‘Body　and　Mind；'　p。　　10）　that　〃reflex　movements　which　commonly　effect　a　useful　end　may；　under　the　changed　circumstances　of　disease；　do　great　mischief；　becoming　even　the　occasion　of　violent　suffering　and　of　a　most　painful　death。〃

It　is　scarcely　credible　that　the　movements　of　a　headless　frog；　when　it　wipes　off　a　drop　of　acid　or　other　object　from　its　thigh；　and　which　movements　are　so　well　coordinated　for　a　special　purpose；　were　not　at　first　performed　voluntarily；　being　afterwards　rendered　easy　through　long…continued　habit　so　as　at　last　to　be　performed　unconsciously；　or　independently　of　the　cerebral　hemispheres。

So　again　it　appears　probable　that　starting　was　originally　acquired　by　the　habit　of　jumping　away　as　quickly　as　possible　from　danger；　whenever　any　of　our　senses　gave　us　warning。　　Starting；　as　we　have　seen；　is　accompanied　by　the　blinking　of　the　eyelids　so　as　to　protect　the　eyes；　the　most　tender　and　sensitive　organs　of　the　body；　and　it　is；　I　believe；　always　accompanied　by　a　sudden　and　forcible　inspiration；　which　is　the　natural　preparation　for　any　violent　effort。　　But　when　a　man　or　horse　starts；　his　heart　beats　wildly　against　his　ribs；　and　here　it　may　be　truly　said　we　have　an　organ　which　has　never　been　under　the　control　of　the　will；　partaking　in　the　general　reflex　movements　of　the　body。　To　this　point；　however；　I　shall　return　in　a　future　chapter。

The　contraction　of　the　iris；　when　the　retina　is　stimulated　by　a　bright　light；　is　another　instance　of　a　movement；　which　it　appears　cannot　possibly　have　been　at　first　voluntarily　performed　and　then　fixed　by　habit；　for　the　iris　is　not　known　to　be　under　the　conscious　control　of　the　will　in　any　animal。　In　such　cases　some　explanation；　quite　distinct　from　habit；　will　have　to　be　discovered。　　The　radiation　of　nerve…force　from　strongly…excited　nerve…cells　to　other　connected　cells；　as　in　the　case　of　a　bright　light　on　the　retina　causing　a　sneeze；　may　perhaps　aid　us　in　understanding　how　some　reflex　actions　originated。　　A　radiation　of　nerve…force　of　this　kind；　if　it　caused　a　movement　tending　to　lessen　the　primary　irritation；　as　in　the　case　of　the　contraction　of　the　iris　preventing　too　much　light　from　falling　on　the　retina；　might　afterwards　have　been　taken　advantage　of　and　modified　for　this　special　purpose。

It　further　deserves　notice　that　reflex　actions　are　in　all　probability　liable　to　slight　variations；　as　are　all　corporeal　structures　and　instincts；　and　any　variations　which　were　beneficial　and　of　sufficient　importance；　would　tend　to　be　preserved　and　inherited。　　Thus　reflex　actions；　when　once　gained　for　one　purpose；　might　afterwards　be　modified　independently　of　the　will　or　habit；　so　as　to　serve　for　some　distinct　purpose。　Such　cases　would　be　parallel　with　those　which；　as　we　have　every　reason　to　believe；　have　occurred　with　many　instincts；　for　although　some　instincts　have　been　developed　simply　through　long…continued　and　inherited　habit；　other　highly　complex　ones　have　been　developed　through　the　preservation　of　variations　of　pre…existing　instincts　that　is；　through　natural　selection。

I　have　discussed　at　some　little　length；　though　as　I　am　well　aware；　in　a　very　imperfect　manner；　the　acquirement　of　reflex　actions；　because　they　are　often　brought　into　play　in　connection　with　movements　expressive　of　our　emotions；　and　it　was　necessary　to　show　that　at　least　some　of　them　might　have　been　Erst　acquired　through　the　will　in　order　to　satisfy　a　desire；　or　to　relieve　a　disagreeable　sensation。


_Associated　habitual　movements　in　the　lower　animals_。　I　have　already　given　in　the　case　of　Man　several　instances　of　movements　associated　with　various　states　of　the　mind　or　body；　which　are　now　purposeless；　but　which　were　originally　of　use；　and　are　still　of　use　under　certain　circumstances。　　As　this　subject　is　very　important　for　us；　I　will　here　give　a　considerable　number　of　analogous　facts；　with　reference　to　animals；　although　many　of　them　are　of　a　very　trifling　nature。　　My　object　is　to　show　that　certain　movements　were　originally　performed　for　a　definite　end；　and　that；　under　nearly　the　same　circumstances；　they　are　still　pertinaciously　performed　through　habit　when　not　of　the　least　use。　That　the　tendency　in　most　of　the　following　cases　is　inherited；　we　may　infer　from　such　actions　being　performed　in　the　same　manner　by　all　the　individuals；　young　and　old；　of　he　same　species。　We　shall　also　see　that　they　are　excited　by　the　most　diversified；　often　circuitous；　and　sometimes　mistaken　associations。

Dogs；　when　they　wish　to　go　to　sleep　on　a　carpet　or　other　hard　surface；　generally　turn　round　and　round　and　scratch　the　ground　with　their　fore…paws　in　a　senseless　manner；　as　if　they　intended　to　trample　down　the　grass　and　scoop　out　a　hollow；　as　no　doubt　their　wild　parents　did；　when　they　lived　on　open　grassy　plains　or　in　the　woods。　　Jackals；　fennecs；　and　other　allied　animals　in　the　Zoological　Gardens；　treat　their　straw　in　this　manner；　but　it　is　a　rather　odd　circumstance　that　the　keepers；　after　observing　for　some　months；　have　never　seen　the　wolves　thus　behave。　A　semi…idiotic　dogand　an　animal　in　this　condition　would　be　particularly　liable　to　follow　a　senseless　habitwas　observed　by　a　friend　to　turn　completely　round　on　a　carpet　thirteen　times　before　going　to　sleep。

Many　carnivorous　animals；　as　they　crawl　towards　their　prey　and　prepare　to　rush　or　spring　on　it；　lower　their　heads　and　crouch；　partly；　as　it　would　appear；　to　hide　themselves；　and　partly　to　get　ready　for　their　rush；　and　this　habit　in　an　exaggerated　form　has　become　hereditary　in　our　pointers　and　setters。　Now　I　have　noticed　scores　of　times　that　when　two　strange　dogs　meet　on　an　open　road；　the　one　which　first　sees　the　other；　though　at　the　distance　of　one　or　two　hundred　yards；　after　the　first　glance　always　lowers　its　bead；　generally　crouches　a　little；　or　even　lies　down；　that　is；　he　takes　the　proper　attitude　for　concealing　himself　and　｛illust。　caption　=　for　making　a　rush　or　FIG。　　4。Small　dog　watching　a　cat　on　a　spring；　although　the　road　table。　From　a　photograph　taken　is　quite　open　and　The　distance　Mr。　Rejlander。｝　great。　Again；　dogs　of　all　kinds　when　intently　watching　and　slowly　approaching　their　prey；　frequently　keep　one　of　their　fore…legs　doubled　up　for　a　long　time；　ready　for　the　next　cautious　step；　and　this　is　eminently　characteristic　of　the　pointer。　　But　from　habit　they　behave　in　exactly　the　same　manner　whenever　their　attention　is　aroused　（fig。　4）。　I　have　seen　a　dog　at　the　foot　of　a　high　wall；　listening　attentively　to　a　sound　on　the　opposite　side；　with　one　leg　doubled　up；　and　in　this　case　there　could　have　been　no　intention　of　making　a　cautious　approach。

Dogs　after　voiding　their　excrement　often　make　with　all　four　feet　a　few　scratches　backwards；　even　on　a　bare　stone　pavement；　as　if　for　the　purpose　of　covering　up　their　excrement　with　earth；　in　nearly　the　same　manner　as　do　cats。　Wolves　and　jackals　behave　in　the　Zoological　Gardens　in　exactly　the　same　manner；　yet；　as　I　am　assured　by　the　keepers；　neither　wolves；　jackals；　nor　foxes；　when　they　have　the　means　of　doing　so；　ever　cover　up　their　excrement；　any　more　than　do　dogs。　All　these　animals；　however；　bury　superfluous　food。　　Hence；　if　we　rightly　understand　the　meaning　of　the　above　cat…like　habit；　of　which　there　can　be　little　doubt；　we　have　a　purposeless　remnant　of　an　habitual　movement；　which　was　originally　followed　by　some　remote　progenitor　of　the　dog…genus　for　a　definite　purpose；　and　which　has　been　retained　for　a　prodigious　length　of　time。

Dogs　and　jackals＇15＇　take　much　pleasure　in　rolling　and　rubbing　their　necks　and　backs　on　carrion。　　The　odour　seems　delightful　to　them；　though　dogs　at　least　do　not　eat　carrion。　Mr。　Bartlett　has　observed　wolves　for　me；　and　has　given　them　carrion；　but　has　never　seen　them　roll　on　it。　　I　have　heard　it　remarked；　and　I　believe　it　to　b