the circulation of the blood-第4部分

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actual　existence　of　the　fact　which　everybody　assumed。　　To　anybody　who
looks　at　the　blood…vessels　with　an　unprejudiced　eye　it　seems　so　natural
that　the　blood　should　all　come　out　of　the　liver；　and　be　distributed　by
the　veins　to　the　different　parts　of　the　body；　that　nothing　can　seem
simpler　or　more　plain；　and　consequently　no　one　could　make　up　his　mind
to　dispute　this　apparently　obvious　assumption。　　But　Harvey　did　dispute
it；　and　when　he　came　to　investigate　the　matter　he　discovered　that　it　was
a　profound　mistake；　and　that；　all　this　time；　the　blood　had　been　moving
in　just　the　opposite　direction；　namely；　from　the　small　ramifications　of
the　veins　towards　the　right　side　of　the　heart。　　Harvey　further　found
that；　in　the　arteries；　the　blood；　as　had　previously　been　known；　was
travelling　from　the　greater　trunks　towards　the　ramifications。　Moreover；
referring　to　the　ideas　of　Columbus　and　of　Galen　（for　he　was　a　great
student　of　literature；　and　did　justice　to　all　his　predecessors）；　Harvey
accepts　and　strengthens　their　view　of　the　course　of　the　blood　through
the　lungs；　and　he　shows　how　it　fitted　into　his　general　scheme。　　If　you
will　follow　the　course　of　the　arrows　in　Fig。　4　you　will　see　at　once
thatin　accordance　with　the　views　of　Columbusthe　blood　passes　from
the　right　side　of　the　heart；　through　the　lungs；　to　the　left　side。　　Then；
adds　Harvey；　with　abundant　proof；　it　passes　through　the　arteries　to　all
parts　of　the　body；　and　then；　at　the　extremities　of　their　branches　in
the　different　parts　of　the　body；　it　passes　（in　what　way　he　could　not
tell；　for　his　means　of　investigation　did　not　allow　him　to　say）　into　the
roots　of　the　ventsthen　from　the　roots　of　the　veins　it　goes　into　the
trunk　and　veinsthen　to　the　right　side　of　the　heartand　then　to　the
lungs；　and　so　on。

That；　you　will　observe；　makes　a　complete　circuit；　and　it　was　precisely
here　that　the　originality　of　Harvey　lay。　　There　never　yet　has　been
produced；　and　I　do　not　believe　there　can　be　produced；　a　tittle　of
evidence　to　show　that；　before　his　time；　any　one　had　the　slightest
suspicion　that　a　single　drop　of　blood；　starting　in　the　left　ventricle
of　the　heart；　passes　through　the　whole　arterial　system；　comes　back
through　the　venous　system；　goes　through　the　lungs；　and　comes　back　to
the　place　whence　it　started。　　But　that　is　the　circulation　of　the　blood；
and　it　was　exactly　this　which　Harvey　was　the　first　man　to　suspect；　to
discover；　and　to　demonstrate。

But　this　was　by　no　means　the　only　thing　Harvey　did。　　He　was　the　first
who　discovered　and　who　demonstrated　the　true　mechanism　of　the　heart's
action。　　No　one；　before　his　time；　conceived　that　the　movement　of　the
blood　was　entirely　due　to　the　mechanical　action　of　the　heart　as　a
pump。　　There　were　all　sorts　of　speculations　about　the　matter；　but　nobody
had　formed　this　conception；　and　nobody　understood　that　the　so…called
systole　of　the　heart　is　a　state　of　active　contraction；　and　the
so…called　diastole　is　a　mere　passive　dilatation。　　Even　within　our　own
age　that　matter　had　been　discussed。　　Harvey　is　as　clear　as　possible
about　it。　　He　says　the　movement　of　the　blood　is　entirely　due　to　the
contractions　of　the　walls　of　the　heartthat　it　is　the　propelling
apparatusand　all　recent　investigation　tends　to　show　that　he　was
perfectly　right。　And　from　this　followed　the　true　theory　of　the　pulse。
Galen　said；　as　I　pointed　out　just　now；　that　the　arteries　dilate　as
bellows；　which　have　an　active　power　of　dilatation　and　contraction；　and
not　as　bags　which　are　blown　out　and　collapse。　　Harvey　said　it　was
exactly　the　contrarythe　arteries　dilate　as　bags　simply　because　the
stroke　of　the　heart　propels　the　blood　into　them；　and；　when　they　relax
again；　they　relax　as　bags　which　are　no　longer　stretched；　simply　because
the　force　of　the　blow　of　the　heart　is　spent。　　Harvey　has　been
demonstrated　to　be　absolutely　right　in　this　statement　of　his；　and　yet；
so　slow　is　the　progress　of　truth；　that；　within　my　time；　the　question　of
the　active　dilatation　of　the　arteries　has　been　discussed。

Thus　Harvey's　contributions　to　physiology　may　be　summed　up　as　follows：
In　the　first　place；　he　was　the　first　person　who　ever　imagined；　and
still　more　who　demonstrated；　the　true　course　of　the　circulation　of　the
blood　in　the　body；　in　the　second　place；　he　was　the　first　person　who
ever　understood　the　mechanism　of　the　heart；　and　comprehended　that　its
contraction　was　the　cause　of　the　motion　of　the　blood；　and　thirdly；　he
was　the　first　person　who　took　a　just　view　of　the　nature　of　the　pulse。
These　are　the　three　great　contributions　which　he　made　to　the　science　of
physiology；　and　I　shall　not　err　in　sayingI　speak　in　the　presence　of
distinguished　physiologists；　but　I　am　perfectly　certain　that　they　will
endorse　what　I　saythat　upon　that　foundation　the　whole　of　our
knowledge　of　the　human　body；　with　the　exception　of　the　motor　apparatus
and　the　sense　organs；　has　been　gradually　built　up；　and　that　upon　that
foundation　the　whole　rests。　　And　not　only　does　scientific　physiology
rest　upon　it；　but　everything　like　scientific　medicine　also　rests　upon
it。　　As　you　knowI　hope　it　is　now　a　matter　of　popular　knowledgeit　is
the　foundation　of　all　rational　speculation　about　morbid　processes；　it
is　the　only　key　to　the　rational　interpretation　of　that　commonest　of　all
indications　of　disease；　the　state　of　the　pulse；　so　that；　both
theoretically　and　practically；　this　discovery；　this　demonstration　of
Harvey's；　has　had　an　effect　which　is　absolutely　incalculable；　and　the
consequences　of　which　will　accumulate　from　age　to　age　until　they　result
in　a　complete　body　of　physiological　science。

Fig。5。The　junction　of　the　arteries　and　veins　by　capillary　tubes；
discovered　by　Malpighi　（A。D。　　1664）。

I　regret　that　I　am　unable　to　pursue　this　subject　much　further；　but　there
is　one　point　I　should　mention。　　In　Harvey's　time；　the　microscope　was
hardly　invented。　　It　is　quite　true　that　in　some　of　his　embryological
researches　he　speaks　of　having　made　use　of　a　hand　glass；　but　that　was
the　most　that　he　seems　to　have　known　anything　about；　or　that　was
accessible　to　him　at　that　day。　And　so　it　came　about；　that；　although　he
examined　the　course　of　the　blood　in　many　of　the　lower　animalswatched
the　pulsation　of　the　heart　in　shrimps；　and　animals　of　that　kindhe
never　could　put　the　final　coping…stone　on　his　edifice。　　He　did　not　know
to　the　day　of　his　death；　although　quite　clear　about　the　fact　that　the
arteries　and　the　veins　do　communicate；　how　it　is　that　they
communicatehow　it　was　that　the　blood　of　the　arteries　passed　into　the
veins。　　One　is　grieved　to　think　that　the　grand　old　man　should　have　gone
down　to　his　tomb　without　the　vast　satisfaction　it　would　have　given　to
him　to　see　what　the　Italian　naturalist　Malpighi　showed　only　seven　years
later；　in　1664；　when　he　demonstrated；　in　a　living　frog；　the　actual
passage　of　the　blood　from　the　ultimate　ramifications　of　the　arteries
into　the　veins。　　But　that　absolute　ocular　demonstration　of　the　truth　of
the　views　he　had　maintained　throughout　his　life　it　was　not　granted　to
Harvey　to　see。　　What　he　did　experience　was　this：　　that　on　the
publication　of　his　doctrines；　they　were　met　with　the　greatest　possible
opposition；　and　I　have　no　doubt　savage　things　were　uttered　in　those　old
controversies；　and　that　a　great　many　people　said　that　these　new…fangled
doctrines；　reducing　living　processes　to　mere　mechanism；　would　sap　the
foundations　of　religion　and　morality。　　I　do　not　know　for　certain　that
they　did；　but　they　said　things　very　like　it。　　The　first　point　was　to
show　that　Harvey's　views　were　absolutely　untrue；　and　not　being　able　to
succeed　in　that；　opponents　said　they　were　not　new；　and　not　being　able
to　succeed　in　that；　that　they　didn't　matter。　　That　is　the　usual　course
with　all　new　discoveries。　　But　Harvey　troubled　himself　very　little
about　these　things。　　He　remained　perfectly　quiet；　for　although　reputed
a　hot…tempered　man；　he　never　would　have　anything　to　do　with　controversy
if　he　could　help　it；　and　he　only　replied　to　one　of　his　antagonists
after　twenty　years'　interval；　and　then　in　the　most　charming　spirit　of
candour　and　moderation。　　But　he　had　the　great　satisfaction　of　living　to
see　his　doctrine　accepted　upon　all　sides。　　At　the　time　of　his　death；
there　was　not　an　anatomical　school　in　Europe　in　which　the　doctrine　of
the　circulation　of　the　blood　was　not　taught　in　the　way　in　which　Harvey
had　laid　it　down。　　In　that　respect　he　had　a　happiness　which　is　granted
to　very　few　men。

I　have　said　that　the　other　great　investigation　of　Harvey　is　not　one
which　can　be　dealt　with　to　a　general　audience。　　It　is　very　complex；　and
therefore　I　must　ask　you　to　take　my　word　for　it　that；　although　not　so
fortunate　an　investigation；　not　so　entirely　accordant　with　later　results
as　the　doctrine　of　the　circulation；　yet　that　still；　this　little
treatise　of　Harvey's　has　in　many　directions　exerted　an　influence　hardly
less　remarkable　than　that　exerted　by　the　Essay　upon　the　Circulation　of
the　Blood。

And　now　let　me　ask　your　attention　to　two　or　three　closing　remarks。

If　you　look　back　upon　that　period　of　about　100　years　which　commences
with　Harvey's　birthI　mean　from　the　year　1578　to　1680　or
thereaboutsI　think　you　will　agree　with　me；　that　it　constitutes　one　of
the　most　remarkable　epochs　in　the　whole　of　that　thousand　years　which　we
may　roughly　reckon　as　constituting　the　history　of　Britain。　　In　the
commencement　of　that　period；　we　may　see；　if　not　the　setting；　at　any
rate　the　declension　of　that　system　of　personal　rule　which　had　existed
under　previous　sovereigns；　and　which；　after　a　brief　and　spasmodic
revival　in　the　time　of　George　the　Third；　has　now　sunk；　let　us　hope；
into　the　limbo　of　forgotten　things。　The　latter　part　of　that　100　years
saw　the　dawn　of　that　system　of　free　government　which　has　grown　and
flourished；　and　which；　if　the　men　of　the　present　day　be　the　worthy
descendants　of　Eliott　and　Pym；　and　Hampden　and　Milton；　will　go　on
growing　as　long　as　this　realm　lasts。　Within　that　time；　one　of　the
strangest　phenomena　which　I　think　I　may　say　any　nation　has　ever
manifested　arose　to　its　height　and　fellI　mean　that　strange　and
altogether　marvellous　phenomenon；　English　Puritanism。　　Within　that
time；　England　had　to　show　statesmen　like　Burleigh；　Strafford；　and
CromwellI　mean　men　who　were