the expression of emotion in man and animals-第16章

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The　males　of　some　lizards；　when　fighting　together　during　their　courtship；　expand　their　throat　pouches　or　frills；　and　erect　their　dorsal　crests。＇16＇　But　Dr。　Gunther　does　not　believe　that　they　can　erect　their　separate　spines　or　scales。

We　thus　see　how　generally　throughout　the　two　higher　vertebrate　classes；　and　with　some　reptiles；　the　dermal　appendages　are　erected　under　the　influence　of　anger　and　fear。　　The　movement　is　effected；　as　we　know　from　Kolliker's　interesting　discovery；　by　the　contraction　of　minute；　unstriped；　involuntary　muscles；＇17＇　often　called　_arrectores　pili_；　which　are　attached　to　the　capsules　of　the　separate　hairs；　feathers；　&c。　By　the　contraction　of　these　muscles　the　hairs　can　be　instantly　erected；　as　we　see　in　a　dog；　being　at　the　same　time　drawn　a　little　out　of　their　sockets；　they　are　afterwards　quickly　depressed。　　The　vast　number　of　these　minute　muscles　over　the　whole　body　of　a　hairy　quadruped　is　astonishing。　The　erection　of　the　hair　is；　however；　aided　in　some　cases；　as　with　that　on　the　head　of　a　man；　by　the　striped　and　voluntary　muscles　of　the　underlying　_panniculus　carnosus_。　　It　is　by　the　action　of　these　latter　muscles；　that　the　hedgehog　erects　its　spines。　It　appears；　also；　from　the　researches　of　Leydig＇18＇　and　others；　that　striped　fibres　extend　from　the　panniculus　to　some　of　the　larger　hairs；　such　as　the　vibrissae　of　certain　quadrupeds。　The　_arrectores　pili_　contract　not　only　under　the　above　emotions；　but　from　the　application　of　cold　to　the　surface。　　I　remember　that　my　mules　and　dogs；　brought　from　a　lower　and　warmer　country；　after　spending　a　night　on　the　bleak　Cordillera；　had　the　hair　all　over　their　bodies　as　erect　as　under　the　greatest　terror。　We　see　the　same　action　in　our　own　_goose…skin_　during　the　chill　before　a　fever…fit。　Mr。　Lister　has　also　found；＇19＇　that　tickling　a　neighbouring　part　of　the　skin　causes　the　erection　and　protrusion　of　the　hairs。


＇15＇　_Melopsittacus　undulatus_。　　See　an　account　of　its　habits　by　Gould；　‘Handbook　of　Birds　of　Australia；'　1865；　vol。　　ii。　　p。　　82。

＇16＇　See；　for　instance；　the　account　which　I　have　given　（‘Descent　of　Man；'　vol。　　ii。　　p。　　32）　of　an　Anolis　and　Draco。

＇17＇　These　muscles　are　described　in　his　well…known　works。　I　am　greatly　indebted　to　this　distinguished　observer　for　having　given　me　in　a　letter　information　on　this　same　subject。

From　these　facts　it　is　manifest　that　the　erection　of　the　dermal　appendages　is　a　reflex　action；　independent　of　the　will；　and　this　action　must　be　looked　at；　when；　occurring　under　the　influence　of　anger　or　fear；　not　as　a　power　acquired　for　the　sake　of　some　advantage；　but　as　an　incidental　result；　at　least　to　a　large　extent；　of　the　sensorium　being　affected。　The　result；　in　as　far　as　it　is　incidental；　may　be　compared　with　the　profuse　sweating　from　an　agony　of　pain　or　terror。　Nevertheless；　it　is　remarkable　how　slight　an　excitement　often　suffices　to　cause　the　hair　to　become　erect；　as　when　two　dogs　pretend　to　fight　together　in　play。　We　have；　also；　seen　in　a　large　number　of　animals；　belonging　to　widely　distinct　classes；　that　the　erection　of　the　hair　or　feathers　is　almost　always　accompanied　by　various　voluntary　movements　by　threatening　gestures；　opening　the　mouth；　uncovering　the　teeth；　spreading　out　of　the　wings　and　tail　by　birds；　and　by　the　utterance　of　harsh　sounds；　and　the　purpose　of　these　voluntary　movements　is　unmistakable。　　Therefore　it　seems　hardly　credible　that　the　co…ordinated　erection　of　the　dermal　appendages；　by　which　the　animal　is　made　to　appear　larger　and　more　terrible　to　its　enemies　or　rivals；　should　be　altogether　an　incidental　and　purposeless　result　of　the　disturbance　of　the　sensorium。　This　seems　almost　as　incredible　as　that　the　erection　by　the　hedgehog　of　its　spines；　or　of　the　quills　by　the　porcupine；　or　of　the　ornamental　plumes　by　many　birds　during　their　courtship。　should　all　be　purposeless　actions。


＇18＇　‘Lehrbuch　der　Histologie　des　Menschen；'　1857；　s。　　82。　　I　owe　to　Prof。　W。　Turner's　kindness　an　extract　from　this　work。

＇19＇　‘Quarterly　Journal　of　Microscopical　Science；'　1853；　vol。　　i。　　p。　　262。

We　here　encounter　a　great　difficulty。　　How　can　the　contraction　of　the　unstriped　and　involuntary　_arrectores　pili_　have　been　co…ordinated　with　that　of　various　voluntary　muscles　for　the　same　special　purpose？　If　we　could　believe　that　the　arrectores　primordially　had　been　voluntary　muscles；　and　had　since　lost　their　stripes　and　become　involuntary；　the　case　would　be　comparatively　simple。　　I　am　not；　however；　aware　that　there　is　any　evidence　in　favour　of　this　view；　although　the　reversed　transition　would　not　have　presented　any　great　difficulty；　as　the　voluntary　muscles　are　in　an　unstriped　condition　in　the　embryos　of　the　higher　animals；　and　in　the　larvae　of　some　crustaceans。　Moreover　in　the　deeper　layers　of　the　skin　of　adult　birds；　the　muscular　network　is；　according　to　Leydig；＇20＇　in　a　transitional　condition；　the　fibres　exhibiting　only　indications　of　transverse　striation。

Another　explanation　seems　possible。　　We　may　admit　that　originally　the　_arrectores　pili_　were　slightly　acted　on　in　a　direct　manner；　under　the　influence　of　rage　and　terror；　by　the　disturbance　of　the　nervous　system；　as　is　undoubtedly　the　case　with　our　so…called　_goose…skin_　before　a　fever…fit。　Animals　have　been　repeatedly　excited　by　rage　and　terror　during　many　generations；　and　consequently　the　direct　effects　of　the　disturbed　nervous　system　on　the　dermal　appendages　will　almost　certainly　have　been　increased　through　habit　and　through　the　tendency　of　nerve…force　to　pass　readily　along　accustomed　channels。　We　shall　find　this　view　of　the　force　of　habit　strikingly　confirmed　in　a　future　chapter；　where　it　will　be　shown　that　the　hair　of　the　insane　is　affected　in　an　extraordinary　manner；　owing　to　their　repeated　accesses　of　fury　and　terror。　As　soon　as　with　animals　the　power　of　erection　had　thus　been　strengthened　or　increased；　they　must　often　have　seen　the　hairs　or　feathers　erected　in　rival　and　enraged　males；　and　the　bulk　of　their　bodies　thus　increased。　　In　this　case　it　appears　possible　that　they　might　have　wished　to　make　themselves　appear　larger　and　more　terrible　to　their　enemies；　by　voluntarily　assuming　a　threatening　attitude　and　uttering　harsh　cries；　such　attitudes　and　utterances　after　a　time　becoming　through　habit　instinctive。　In　this　manner　actions　performed　by　the　contraction　of　voluntary　muscles　might　have　been　combined　for　the　same　special　purpose　with　those　effected　by　involuntary　muscles。　It　is　even　possible　that　animals；　when　excited　and　dimly　conscious　of　some　change　in　the　state　of　their　hair；　might　act　on　it　by　repeated　exertions　of　their　attention　and　will；　for　we　have　reason　to　believe　that　the　will　is　able　to　influence　in　an　obscure　manner　the　action　of　some　unstriped　or　involuntary　muscles；　as　in　the　period　of　the　peristaltic　movements　of　the　intestines；　and　in　the　contraction　of　the　bladder。　Nor　must　we　overlook　the　part　which　variation　and　natural　selection　may　have　played；　for　the　males　which　succeeded　in　making　themselves　appear　the　most　terrible　to　their　rivals；　or　to　their　other　enemies；　if　not　of　overwhelming　power；　will　on　an　average　have　left　more　offspring　to　inherit　their　characteristic　qualities；　whatever　these　may　be　and　however　first　acquired；　than　have　other　males。


＇20＇　‘Lehrbuch　der　Histologie；'　1857；　s。　　82。

_The　inflation　of　the　body；　and　other　means　of　exciting　fear　in　an　enemy_。Certain　Amphibians　and　Reptiles；　which　either　have　no　spines　to　erect；　or　no　muscles　by　which　they　can　be　erected；　enlarge　themselves　when　alarmed　or　angry　by　inhaling　air。　This　is　well　known　to　be　the　case　with　toads　and　frogs。　The　latter　animal　is　made；　in　AEsop's　fable　of　the　‘Ox　and　the　Frog；'　to　blow　itself　up　from　vanity　and　envy　until　it　burst。　This　action　must　have　been　observed　during　the　most　ancient　times；　as；　according　to　Mr。　Hensleigh　Wedgwood；＇21＇　the　word　_toad_　expresses　in　all　the　languages　of　Europe　the　habit　of　swelling。　　It　has　been　observed　with　some　of　the　exotic　species　in　the　Zoological　Gardens；　and　Dr。　Gunther　believes　that　it　is　general　throughout　the　group。　Judging　from　analogy；　the　primary　purpose　probably　was　to　make　the　body　appear　as　large　and　frightful　as　possible　to　an　enemy；　but　another；　and　perhaps　more　important　secondary　advantage　is　thus　gained。　When　frogs　are　seized　by　snakes；　which　are　their　chief　enemies；　they　enlarge　themselves　wonderfully；　so　that　if　the　snake　be　of　small　size；　as　Dr。　Gunther　informs　me；　it　cannot　swallow　the　frog；　which　thus　escapes　being　devoured。


＇21＇　‘Dictionary　of　English　Etymology；'　p。　　403。

Chameleons　and　some　other　lizards　inflate　themselves　when　angry。　Thus　a　species　inhabiting　Oregon；　the　_Tapaya　Douglasii_；　is　slow　in　its　movements　and　does　not　bite；　but　has　a　ferocious　aspect；　〃when　irritated　it　springs　in　a　most　threatening　manner　at　anything　pointed　at　it；　at　the　same　time　opening　its　mouth　wide　and　hissing　audibly；　after　which　it　inflates　its　body；　and　shows　other　marks　of　anger。〃＇22＇

Several　kinds　of　snakes　likewise　inflate　themselves　when　irritated。　The　puff…adder　（_Clotho　arietans_）　is　remarkable　in　this　respect；　but　I　believe；　after　carefully　watching　these　animals；　that　they　do　not　act　thus　for　the　sake　of　increasing　their　apparent　bulk；　but　simply　for　inhaling　a　large　supply　of　air；　so　as　to　produce　their　surprisingly　loud；　harsh；　and　prolonged　hissing　sound。　The　Cobras…de…capello；　when　irritated；　enlarge　themselves　a　little；　and　hiss　moderately；　but；　at　the　same　time　they　lift　their　heads　aloft；　and　dilate　by　means　of　their　elongated　anterior　ribs；　the　skin　on　each　side　of　the　neck　into　a　large　flat　disk；the　so…called　hood。　With　their　widely　opened　mouths；　they　then　assume　a　terrific　aspect。　The　benefit　thus　derived　ought　to　be　considerable；　in　order　to　compensate　for　the　somewhat　lessened　rapidity　（though　this　is　still　great）　with　which；　when　dilated；　they　can　strike　at　their　enemies　or　prey；　on　the　same　principle　that　a　broad；　thin　piece　of　wood　cannot　be　moved　through　the　air　so　quickly　as　a　small　round　stick。　An　innocuous　snake；　the　_Trovidonotus　macrophthalmus_；　an　inhabitant　of　India；　likewise　dilates　its　neck　when　irritated；　and　consequently　is　often　mistaken　for　its　compatriot；　the　deadly　Cobra。＇23＇　This　resemblance　perhaps　serves　as　some　protection　to　the　Tropidonotus。


＇21＇　See　the　account　of　the　habits　of　this　animal　by　Dr；　Cooper；　as　quoted　in　‘Nature；'　April　27；　1871；　p。　　512。

＇22＇　Dr。　Gunther；　‘Reptiles　of　British　India；'　p。　　262。

Another　innocuous　species；　the　Dasypeltis　of　South　Africa；　blows　itself　out；　distends　its　neck；　hisses　and　darts　at　an　intruder。＇24＇　Many　other　snakes　hiss　under　similar　circumstances。　They　also　rapidly　vibrate　their　protruded　tongues；　and　this　may　aid　in　increasing　their　terrific　appearance。

Snakes　possess　other　means　of　producing　sounds　besides　hissing。　Many　years　ago　I　observed　in　South　America　that　a　venomous　Trigonocephalus；　when　disturbed；　rapidly　vibrated　the　end　of　its　tail；　which　striking　against　the　dry　grass　and　twigs　produced　a　rattling　noise　that　could　be　distinctly　heard　at　the　distance　of　six　feet。＇25＇　The　deadly　and　fierce　_Echis　carinata_　of　India　produces　〃a　curious　prolonged；　almost　hissing　sound　in　a　very　different　manner；　namely　by　rubbing　〃the　sides　of　the　folds　of　its　body　against　each　other；〃　whilst　the　head　r