the circulation of the blood-第1章

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The　Circulation　of　the　Blood


by　Thomas　H。　Huxley





I　DESIRE　this　evening　to　give　you　some　account　of　the　life　and　labours
of　a　very　noble　EnglishmanWilliam　Harvey。

William　Harvey　was　born　in　the　year　1578；　and　as　he　lived　until　the　year
1657；　he　very　nearly　attained　the　age　of　80。　　He　was　the　son　of　a　small
landowner　in　Kent；　who　was　sufficiently　wealthy　to　send　this；　his
eldest　son；　to　the　University　of　Cambridge；　while　he　embarked　the
others　in　mercantile　pursuits；　in　which　they　all；　as　time　passed　on；
attained　riches。

William　Harvey；　after　pursuing　his　education　at　Cambridge；　and　taking
his　degree　there；　thought　it　was　advisableand　justly　thought　so；　in
the　then　state　of　University　educationto　proceed　to　Italy；　which　at
that　time　was　one　of　the　great　centres　of　intellectual　activity　in
Europe；　as　all　friends　of　freedom　hope　it　will　become　again；　sooner　or
later。　　In　those　days　the　University　of　Padua　had　a　great　renown；　and
Harvey　went　there　and　studied　under　a　man　who　was　then　very
famousFabricius　of　Aquapendente。　　On　his　return　to　England；　Harvey
became　a　member　of　the　College　of　Physicians　in　London；　and　entered
into　practice；　and；　I　suppose；　as　an　indispensable　step　thereto；
proceeded　to　marry。　　He　very　soon　became　one　of　the　most　eminent
members　of　the　profession　in　London；　and；　about　the　year　1616；　he　was
elected　by　the　College　of　Physicians　their　Professor　of　Anatomy。　　It
was　while　Harvey　held　this　office　that　he　made　public　that　great
discovery　of　the　circulation　of　the　blood　and　the　movements　of　the
heart；　the　nature　of　which　I　shall　endeavour　by…and…by　to　explain　to　you
at　length。　　Shortly　afterwards；　Charles　the　First　having　succeeded　to
the　throne　in　1625；　Harvey　became　one　of　the　king's　physicians；　and　it
is　much　to　the　credit　of　the　unfortunate　monarchwho；　whatever　his
faults　may　have　been；　was　one　of　the　few　English　monarchs　who　have　shown
a　taste　for　art　and　sciencethat　Harvey　became　his　attached　and
devoted　friend　as　well　as　servant；　and　that　the　king；　on　the　other
hand；　did　all　he　could　to　advance　Harvey's　investigations。　　But；　as　you
know；　evil　times　came　on；　and　Harvey；　after　the　fortunes　of　his　royal
master　were　broken；　being　then　a　man　of　somewhat　advanced　yearsover
60　years　of　age；　in　factretired　to　the　society　of　his　brothers　in　and
near　London；　and　among　them　pursued　his　studies　until　the　day　of　his
death。　　Harvey's　career　is　a　life　which　offers　no　salient　points　of
interest　to　the　biographer。　　It　was　a　life　devoted　to　study　and
investigation；　and　it　was　a　life　the　devotion　of　which　was　amply
rewarded；　as　I　shall　have　occasion　to　point　out　to　you；　by　its　results。

Harvey；　by　the　diversity；　the　variety；　and　the　thoroughness　of　his
investigations；　was　enabled　to　give　an　entirely　new　direction　to　at
least　two　branchesand　two　of　the　most　important　branchesof　what
now…a…days　we　call　Biological　Science。　　On　the　one　hand；　he　founded　all
our　modern　physiology　by　the　discovery　of　the　exact　nature　of　the
motions　of　the　heart；　and　of　the　course　in　which　the　blood　is　propelled
through　the　body；　and；　on　the　other；　he　laid　the　foundation　of　that
study　of　development　which　has　been　so　much　advanced　of　late　years；　and
which　constitutes　one　of　the　great　pillars　of　the　doctrine　of　evolution。
This　doctrine；　I　need　hardly　tell　you；　is　now　tending　to　revolutionise
our　conceptions　of　the　origin　of　living　things；　exactly　in　the　same　way
as　Harvey's　discovery　of　the　circulation　in　the　seventeeth　century
revolutionised　the　conceptions　which　men　had　previously　entertained　with
regard　to　physiological　processes。

It　would；　I　regret；　be　quite　impossible　for　me　to　attempt；　in　the　course
of　the　time　I　can　presume　to　hold　you　here；　to　unfold　the　history　of
more　than　one　of　these　great　investigations　of　Harvey。　　I　call　them
〃great　investigations；〃　as　distinguished　from　〃large　publications。〃　　I
have　in　my　hand　a　little　book；　which　those　of　you　who　are　at　a　great
distance　may　have　some　difficulty　in　seeing；　and　which　I　value　very
much。　　It　is；　I　am　afraid；　sadly　thumbed　and　scratched　with　annotations
by　a　very　humble　successor　and　follower　of　Harvey。　　This　little　book　is
the　edition　of　1651　of　the　'Exercitationes　de　Generatione'；　and　if　you
were　to　add　another　little　book；　printed　in　the　same　small　type；　and
about　one…seventh　of　the　thickness；　you　would　have　the　sum　total　of　the
printed　matter　which　Harvey　contributed　to　our　literature。　And　yet　in
that　sum　total　was　contained；　I　may　say；　the　materials　of　two
revolutions　in　as　many　of　the　main　branches　of　biological　science。　　If
Harvey's　published　labours　can　be　condensed　into　so　small　a　compass；
you　must　recollect　that　it　is　not　because　he　did　not　do　a　great　deal
more。　　We　know　very　well　that　he　did　accumulate　a　very　considerable
number　of　observations　on　the　most　varied　topics　of　medicine；　surgery；
and　natural　history。　　But；　as　I　mentioned　to　you　just　now；　Harvey；　for
a　time；　took　the　royal　side　in　the　domestic　quarrel　of　the　Great
Rebellion；　as　it　is　called；　and　the　Parliament；　not　unnaturally
resenting　that　action　of　his；　sent　soldiers　to　seize　his　papers。　　And
while　I　imagine　they　found　nothing　treasonable　among　those　papers；　yet；
in　the　process　of　rummaging　through　them；　they　destroyed　all　the
materials　which　Harvey　had　spent　a　laborious　life　in　accumulating；　and
hence　it　is　that　the　man's　work　and　labours　are　represented　by　so
little　in　apparent　bulk。

What　I　chiefly　propose　to　do　to…night　is　to　lay　before　you　an　account　of
the　nature　of　the　discovery　which　Harvey　made；　and　which　is　termed　the
Discovery　of　the　Circulation　of　the　Blood。　　And　I　desire　also；　with
some　particularity；　to　draw　your　attention　to　the　methods　by　which　that
discovery　was　achieved；　for；　in　both　these　respects；　I　think；　there　will
be　much　matter　for　profitable　reflection。

Let　me　point　out　to　you；　in　the　first　place；　with　respect　to　this
important　matter　of　the　movements　of　the　heart　and　the　course　of　the
blood　in　the　body；　that　there　is　a　certain　amount　of　knowledge　which
must　have　been　obtained　without　men　taking　the　trouble　to　seek
itknowledge　which　must　have　been　taken　in；　in　the　course　of　time；　by
everybody　who　followed　the　trade　of　a　butcher；　and　still　more　so　by
those　people　who；　in　ancient　times；　professed　to　divine　the　course　of
future　events　from　the　entrails　of　animals。　　It　is　quite　obvious　to
all；　from　ordinary　accidents；　that　the　bodies　of　all　the　higher　animals
contain　a　hot　red　fluidthe　blood。　　Everybody　can　see　upon　the　surface
of　some　part　of　the　skin；　underneath　that　skin；　pulsating　tubes；　which
we　know　as　the　arteries。　　Everybody　can　see　under　the　surface　of　the
skin　more　delicate　and　softer　looking　tubes；　which　do　not　pulsate；　which
are　of　a　bluish　colour；　and　are　termed　the　veins。　　And　every　person　who
has　seen　a　recently　killed　animal　opened　knows　that　these　two　kinds　of
tubes　to　which　I　have　just　referred；　are　connected　with　an　apparatus
which　is　placed　in　the　chest；　which　apparatus；　in　recently　killed
animals；　is　still　pulsating。　　And　you　know　that　in　yourselves　you　can
feel　the　pulsation　of　this　organ；　the　heart；　between　the　fifth　and
sixth　ribs。　　I　take　it　that　this　much　of　anatomy　and　physiology　has
been　known　from　the　oldest　times；　not　only　as　a　matter　of　curiosity；
but　because　one　of　the　great　objects　of　men；　from　their　earliest
recorded　existence；　has　been　to　kill　one　another；　and　it　was　a　matter
of　considerable　importance　to　know　which　was　the　best　place　for　hitting
an　enemy。　　I　can　refer　you　to　very　ancient　records　for　most　precise　and
clear　information　that　one　of　the　best　places　is　to　smite　him　between
the　fifth　and　sixth　ribs。　　Now　that　is　a　very　good　piece　of　regional
anatomy；　for　that　is　the　place　where　the　heart　strikes　in　its
pulsations；　and　the　use　of　smiting　there　is　that　you　go　straight　to　the
heart。　　Well；　all　that　must　have　been　known　from　time　immemorialat
least　for　4；000　or　5；000　years　before　the　commencement　of　our
erabecause　we　know　that　for　as　great　a　period　as　that　the　Egyptians；
at　any　rate；　whatever　may　have　been　the　case　with　other　people；　were　in
the　enjoyment　of　a　highly　developed　civilisation。　　But　of　what
knowledge　they　may　have　possessed　beyond　this　we　know　nothing；　and　in
tracing　back　the　springs　of　the　origin　of　everything　that　we　call
〃modern　science〃　（which　is　not　merely　knowing；　but　knowing
systematically；　and　with　the　intention　and　endeavour　to　find　out　the
causal　connection　of　things）I　say　that　when　we　trace　back　the
different　lines　of　all　the　modern　sciences　we　come　at　length　to　one
epoch　and　to　one　countrythe　epoch　being　about　the　fourth　and　fifth
centuries　before　Christ；　and　the　country　being　ancient　Greece。　　It　is
there　that　we　find　the　commencement　and　the　root　of　every　branch　of
physical　science　and　of　scientific　method。　　If　we　go　back　to　that　time
we　have　in　the　works　attributed　to　Aristotle；　who　flourished　between
300　and　400　years　before　Christ；　a　sort　of　encyclopaedia　of　the
scientific　knowledge　of　that　dayand　a　very　marvellous　collection　of；
in　many　respects；　accurate　and　precise　knowledge　it　is。　　But；　so　far　as
regards　this　particular　topic；　Aristotle；　it　must　be　confessed；　has　not
got　very　far　beyond　common　knowledge。　　He　knows　a　little　about　the
structure　of　the　heart。　　I　do　not　think　that　his　knowledge　is　so
inaccurate　as　many　people　fancy；　but　it　does　not　amount　to　much。　　A　very
few　years　after　his　time；　however；　there　was　a　Greek　philosopher；
Erasistratus；　who　lived　about　three　hundred　years　before　Christ；　and
who　must　have　pursued　anatomy　with　much　care；　for　he　made　the　important
discovery　that　there　are　membranous　flaps；　which　are　now　called
〃valves；〃　at　the　origins　of　the　great　vessels；　and　that　there　are
certain　other　valves　in　the　interior　of　the　heart　itself。

Fig。　1。The　apparatus　of　the　circulation；　as　at　present　known。　　The
capillary　vessels；　which　connect　the　arteries　and　veins；　are　omitted；
on　account　of　their　small　size。　　The　shading　of　the　〃venous　system〃　is
given　to　all　the　vessels　which　contain　venous　blood；　that　of　the
〃arterial　system〃　to　all　the　vessels　which　contain　arterial　blood。

I　have　here　（Fig。　1）　a　purposely　rough；　but；　so　far　as　it　goes；
accurate；　diagram　of　the　structure　of　the　heart　and　the　course　of　the
blood。　　The　heart　is　supposed　to　be　divided　into　two　portions。　　It
would　be　possible；　by　very　careful　dissection；　to　split　the　heart　down
the　middle　of　a　partition；　or　so…called　'septum'；　which　exists　in　it；
and　to　divide　it　into　the　two　portions　which　you　see　here　represented；
in　which　case　we　should　have　a　left　heart　and　a　right　heart；　quite
distinct　from　one　another。　　You　will　observe　that　there　is　a　portion　of
each　heart　which　is　what　is　called　the　ventricle。　　Now　the　ancients
applied　the　term　'heart'　simply　and　solely　to　the　ventricles。　　They　did
not　count　the　rest　of　the　heartwhat　we　now　speak　of　as　the
'auricles'as　any　part　of　the　heart　at　all；　but　when　they　spoke　of　the
heart　they　meant　the　left　and　the　right　ventricles；　and　they　described
those　great　vessels；　which　we　now　call　the　'pulmonary　veins'　and　the
'vena　cava'；　as　opening　directly　into　the　heart　itself。

What　Erasistratus　made　out　was　that；　at　the　roots　of