res　of　the　orbicularis；　and　this　is　a　provision　for　supporting　and　defending　the　vascular　system　of　the　interior　of　the　eye　from　a　retrograde　impulse　communicated　to　the　blood　in　the　veins　at　that　time。　When　we　contract　the　chest　and　expel　the　air；　there　is　a　retardation　of　the　blood　in　the　veins　of　the　neck　and　head；　and　in　the　more　powerful　acts　of　expulsion；　the　blood　not　only　distends　the　vessels；　but　is　even　regurgitated　into　the　minute　branches。　Were　the　eye　not　properly　compressed　at　that　time；　and　a　resistance　given　to　the　shock；　irreparable　injury　might　be　inflicted　on　the　delicate　textures　of　the　interior　of　the　eye。〃　He　further　adds；　〃If　we　separate　the　eyelids　of　a　child　to　examine　the　eye；　while　it　cries　and　struggles　with　passion；　by　taking　off　the　natural　support　to　the　vascular　system　of　the　eye；　and　means　of　guarding　it　against　the　rush　of　blood　then　occurring；　the　conjunctiva　becomes　suddenly　filled　with　blood；　and　the　eyelids　everted。〃
  ＇12＇　‘The　Anatomy　of　Expression；'　1844；　p。　　106。　　See　also　his　paper　in　the　‘Philosophical　Transactions；'　1822；　p。　　284；　ibid。　　1823；　pp。　166　and　289。　　Also　‘The　Nervous　System　of　the　Human　Body；'　3rd　edit。　1836；　p。　　175。
  Not　only　are　the　muscles　round　the　eyes　strongly　contracted；　as　Sir　C。　Bell　states　and　as　I　have　often　observed；　during　screaming；　loud　laughter；　coughing；　and　sneezing；　but　during　several　other　analogous　actions。　A　man　contracts　these　muscles　when　he　violently　blows　his　nose。　I　asked　one　of　my　boys　to　shout　as　loudly　as　he　possibly　could；　and　as　soon　as　he　began；　he　firmly　contracted　his　orbicular　muscles；　I　observed　this　repeatedly；　and　on　asking　him　why　he　had　every　time　so　firmly　closed　his　eyes；　I　found　that　he　was　quite　unaware　of　the　fact：　he　had　acted　instinctively　or　unconsciously。
  It　is　not　necessary；　in　order　to　lead　to　the　contraction　of　these　muscles；　that　air　should　actually　be　expelled　from　the　chest；　it　suffices　that　the　muscles　of　the　chest　and　abdomen　should　contract　with　great　force；　whilst　by　the　closure　of　the　glottis　no　air　escapes。　In　violent　vomiting　or　retching　the　diaphragm　is　made　to　descend　by　the　chest　being　filled　with　air；　it　is　then　held　in　this　position　by　the　closure　of　the　glottis；　〃as　well　as　by　the　contraction　of　its　own　fibres。〃＇13＇　The　abdominal　muscles　now　contract　strongly　upon　the　stomach；　its　proper　muscles　likewise　contracting；　and　the　contents　are　thus　ejected。　During　each　effort　of　vomiting　〃the　head　becomes　greatly　congested；　so　that　the　features　are　red　and　swollen；　and　the　large　veins　of　the　face　and　temples　visibly　dilated。〃　　At　the　same　time；　as　I　know　from　observation；　the　muscles　round　the　eyes　are　strongly　contracted。　This　is　likewise　the　case　when　the　abdominal　muscles　act　downwards　with　unusual　force　in　expelling　the　contents　of　the　intestinal　canal。
  ＇13＇　See　Dr。　Brinton's　account　of　the　act　of　vomiting；　in　Todd's　Cyclop。　of　Anatomy　and　Physiology；　1859；　vol。　　v。　　Supplement；　p。　　318。
  The　greatest　exertion　of　the　muscles　of　the　body；　if　those　of　the　chest　are　not　brought　into　strong　action　in　expelling　or　compressing　the　air　within　the　lungs；　does　not　lead　to　the　contraction　of　the　muscles　round　the　eyes。　I　have　observed　my　sons　using　great　force　in　gymnastic　exercises；　as　in　repeatedly　raising　their　suspended　bodies　by　their　arms　alone；　and　in　lifting　heavy　weights　from　the　ground；　but　there　was　hardly　any　trace　of　contraction　in　the　muscles　round　the　eyes。
  As　the　contraction　of　these　muscles　for　the　protection　of　the　eyes　during　violent　expiration　is　indirectly；　as　we　shall　hereafter　see；　a　fundamental　element　in　several　of　our　most　important　expressions；　I　was　extremely　anxious　to　ascertain　how　far　Sir　C。　Bell's　view　could　be　substantiated。　Professor　Donders；　of　Utrecht；＇14＇　well　known　as　one　of　the　highest　authorities　in　Europe　on　vision　and　on　the　structure　of　the　eye；　has　most　kindly　undertaken　for　me　this　investigation　with　the　aid　of　the　many　ingenious　mechanisms　of　modern　science；　and　has　published　the　results。＇15＇　He　shows　that　during　violent　expiration　the　external；　the　intra…ocular；　and　the　retro…ocular　vessels　of　the　eye　are　all　affected　in　two　ways；　namely　by　the　increased　pressure　of　the　blood　in　the　arteries；　and　by　the　return　of　the　blood　in　the　veins　being　impeded。　It　is；　therefore；　certain　that　both　the　arteries　and　the　veins　of　the　eye　are　more　or　less　distended　during　violent　expiration。　The　evidence　in　detail　may　be　found　in　Professor　Donders'　valuable　memoir。　　We　see　the　effects　on　the　veins　of　the　head；　in　their　prominence；　and　in　the　purple　colour　of　the　face　of　a　man　who　coughs　violently　from　being　half　choked。　I　may　mention；　on　the　same　authority；　that　the　whole　eye　certainly　advances　a　little　during　each　violent　expiration。　This　is　due　to　the　dilatation　of　the　retro…ocular　vessels；　and　might　have　been　expected　from　the　intimate　connection　of　the　eye　and　brain；　the　brain　being　known　to　rise　and　fall　with　each　respiration；　when　a　portion　of　the　skull　has　been　removed；　and　as　may　be　seen　along　the　unclosed　sutures　of　infants'　heads。　This　also；　I　presume；　is　the　reason　that　the　eyes　of　a　strangled　man　appear　as　if　they　were　starting　from　their　sockets。
  ＇14＇　I　am　greatly　indebted　to　Mr。　Bowman　for　having　introduced　me　to　Prof。　Donders；　and　for　his　aid　in　persuading　this　great　physiologist　to　undertake　the　investigation　of　the　present　subject。　I　am　likewise　much　indebted　to　Mr。　Bowman　for　having　given　me；　with　the　utmost　kindness；　information　on　many　points。
  ＇15＇　This　memoir　first　appeared　in　the　‘Nederlandsch　Archief　voor　Genees　en　Natuurkiinde；'　Deel　5；　1870。　　It　has　been　translated　by　Dr。　W。　D。　Moore；　under　the　title　of　〃On　the　Action　of　the　Eyelids　in　determination　of　Blood　from　expiratory　effort；〃　in　‘Archives　of　Medicine；'　edited　by　Dr。　L。　S。　Beale；　1870；　vol。　　v。　　p。　　20。
  With　respect　to　the　protection　of　the　eye　during　violent　expiratory　efforts　by　the　pressure　of　the　eyelids；　Professor　Donders　concludes　from　his　various　observations　that　this　action　certainly　limits　or　entirely　removes　the　dilatation　of　the　vessels。＇16＇　At　such　times；　he　adds；　we　not　unfrequently　see　the　hand　involuntarily　laid　upon　the　eyelids；　as　if　the　better　to　support　and　defend　the　eyeball。
  ＇16＇　Prof。　Donders　remarks　（ibid。　p。　　28）；　that；　〃After　injury　to　the　eye；　after　operations；　and　in　some　forms　of　internal　inflammation；　we　attach　great　value　to　the　uniform　support　of　the　closed　eyelids；　and　we　increase　this　in　many　instances　by　the　application　of　a　bandage。　In　both　cases　we　carefully　endeavour　to　avoid　great　expiratory　pressure；　the　disadvantage　of　which　is　well　known。〃　　Mr。　Bowman　informs　me　that　in　the　excessive　photophobia；　accompanying　what　is　called　scrofulous　ophthalmia　in　children；　when　the　light　is　so　very　painful　that　during　weeks　or　months　it　is　constantly　excluded　by　the　most　forcible　closure　of　the　lids；　he　has　often　been　struck　on　opening　the　lids　by　the　paleness　of　the　eye；　not　an　unnatural　paleness；　but　an　absence　of　the　redness　that　might　have　been　expected　when　the　surface　is　somewhat　inflamed；　as　is　then　usually　the　case；　and　this　paleness　he　is　inclined　to　attribute　to　the　forcible　closure　of　the　eyelids。
  Nevertheless　much　evidence　cannot　at　present　be　advanced　to　prove　that　the　eye　actually　suffers　injury　from　the　want　of　support　during　violent　expiration；　but　there　is　some。　It　is　〃a　fact　that　forcible　expiratory　efforts　in　violent　coughing　or　vomiting；　and　especially　in　sneezing；　sometimes　give　rise　to　ruptures　of　the　little　（external）　vessels〃　of　the　eye。＇17＇　With　respect　to　the　internal　vessels；　Dr。　Gunning　has　lately　recorded　a　case　of　exophthalmos　in　consequence　of　whooping…cough；　which　in　his　opinion　depended　on　the　rupture　of　the　deeper　vessels；　and　another　analogous　case　has　been　recorded。　　But　a　mere　sense　of　discomfort　would　probably　suffice　to　lead　to　the　associated　habit　of　protecting　the　eyeball　by　the　contraction　of　the　surrounding　muscles。　Even　the　expectation　or　chance　of　injury　would　probably　be　sufficient；　in　the　same　manner　as　an　object　moving　too　near　the　eye　induces　involuntary　winking　of　the　eyelids。　We　may；　therefore；　safely　conclude　from　Sir　C。　Bell's　observations；　and　more　especially　from　the　more　careful　investigations　by　Professor　Donders；　that　the　firm　closure　of　the　eyelids　during　the　screaming　of　children　is　an　action　full　of　meaning　and　of　real　service。
  We　have　already　seen　that　the　contraction　of　the　orbicular　muscles　leads　to　the　drawing　up　of　the　upper　lip；　and　consequently；　if　the　mouth　is　kept　widely　open；　to　the　drawing　down　of　the　corners　by　the　contraction　of　the　depressor　muscles。　The　formation　of　the　naso…labial　fold　on　the　cheeks　likewise　follows　from　the　drawing　up　of　the　upper　lip。　　Thus　all　the　chief　expressive　movements　of　the　face　during　crying　apparently　result　from　the　contraction　of　the　muscles　round　the　eyes。　We　shall　also　find　that　the　shedding　of　tears　depends　on；　or　at　least　stands　in　some　connection　with；　the　contraction　of　these　same　muscles。
  ＇17＇　Donders；　ibid。　　p。　　36。
  In　some　of　the　foregoing　cases；　especially　in　those　of　sneezing　and　coughing；　it　is　possible　that　the　contraction　of　the　orbicular　muscles　may　serve　in　addition　to　protect　the　eyes　from　too　severe　a　jar　or　vibrati