essays on life, art and science-第35章

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it　should　be　otherwise。　　Truth　is　like　moneylightly　come；　lightly
go；　and　if　she　cannot　hold　her　own　against　even　gross
misrepresentation；　she　is　herself　not　worth　holding。
Misrepresentation　in　the　long　run　makes　Truth　as　much　as　it　mars
her；　hence　our　law　courts　do　not　think　it　desirable　that　pleaders
should　speak　their　bona　fide　opinions；　much　less　that　they　should
profess　to　do　so。　　Rather　let　each　side　hoodwink　judge　and　jury　as
best　it　can；　and　let　truth　flash　out　from　collision　of　defence　and
accusation。　　When　either　side　will　not　collide；　it　is　an　axiom　of
controversy　that　it　desires　to　prevent　the　truth　from　being
elicited。

Let　us　now　note　the　courses　forced　upon　biologists　by　the
difficulties　of　Mr。　Darwin's　distinctive　feature。　　Mr。　Darwin　and
Mr。　Wallace；　as　is　well　known；　brought　the　feature　forward
simultaneously　and　independently　of　one　another；　but　Mr。　Wallace
always　believed　in　it　more　firmly　than　Mr。　Darwin　did。　　Mr。　Darwin
as　a　young　man　did　not　believe　in　it。　　He　wrote　before　1889；
〃Nature；　by　making　habit　omnipotent　and　its　effects　hereditary；　has
fitted　the　Fuegian　for　the　climate　and　productions　of　his　country；〃
｛21｝　a　sentence　than　which　nothing　can　coincide　more　fully　with　the
older　view　that　use　and　disuse　were　the　main　purveyors　of
variations；　or　conflict　more　fatally　with　his　own　subsequent
distinctive　feature。　　Moreover；　as　I　showed　in　my　last　work　on
evolution；　｛22｝　in　the　peroration　to　his　〃Origin　of　Species；〃　he
discarded　his　accidental　variations　altogether；　and　fell　back　on　the
older　theory；　so　that　the　body　of　the　〃Origin　of　Species〃　supports
one　theory；　and　the　peroration　another　that　differs　from　it　toto
caelo。　　Finally；　in　his　later　editions；　he　retreated　indefinitely
from　his　original　position；　edging　always　more　and　more　continually
towards　the　theory　of　his　grandfather　and　Lamarck。　　These　facts
convince　me　that　he　was　at　no　time　a　thorough…going　Darwinian；　but
was　throughout　an　unconscious　Lamarckian；　though　ever　anxious　to
conceal　the　fact　alike　from　himself　and　from　his　readers。

Not　so　with　Mr。　Wallace；　who　was　both　more　outspoken　in　the　first
instance；　and　who　has　persevered　along　the　path　of　Wallaceism　just
as　Mr。　Darwin　with　greater　sagacity　was　ever　on　the　retreat　from
Darwinism。　　Mr。　Wallace's　profounder　faith　led　him　in　the　outset　to
place　his　theory　in　fuller　daylight　than　Mr。　Darwin　was　inclined　to
do。　　Mr。　Darwin　just　waved　Lamarck　aside；　and　said　as　little　about
him　as　he　could；　while　in　his　earlier　editions　Erasmus　Darwin　and
Buffon　were　not　so　much　as　named。　　Mr。　Wallace；　on　the　contrary；　at
once　raised　the　Lamarckian　spectre；　and　declared　it　exorcised。　　He
said　the　Lamarckian　hypothesis　was　〃quite　unnecessary。〃　　The　giraffe
did　not　〃acquire　its　long　neck　by　desiring　to　reach　the　foliage　of
the　more　lofty　shrubs；　and　constantly　stretching　its　neck　for　this
purpose；　but　because　any　varieties　which　occurred　among　its
antitypes　with　a　longer　neck　than　usual　at　once　secured　a　fresh
range　of　pasture　over　the　same　ground　as　their　shorter…necked
companions；　and　on　the　first　scarcity　of　food　were　thus　enabled　to
outlive　them。〃　｛23｝

〃Which　occurred〃　is　evidently　〃which　happened　to　occur〃　by　some
chance　or　accident　unconnected　with　use　and　disuse。　　The　word
〃accident〃　is　never　used；　but　Mr。　Wallace　must　be　credited　with　this
instance　of　a　desire　to　give　his　readers　a　chance　of　perceiving　that
according　to　his　distinctive　feature　evolution　is　an　affair　of　luck；
rather　than　of　cunning。　　Whether　his　readers　actually　did　understand
this　as　clearly　as　Mr。　Wallace　doubtless　desired　that　they　should；
and　whether　greater　development　at　this　point　would　not　have　helped
them　to　fuller　apprehension；　we　need　not　now　inquire。　　What　was
gained　in　distinctness　might　have　been　lost　in　distinctiveness；　and
after　all　he　did　technically　put　us　upon　our　guard。

Nevertheless　he　too　at　a　pinch　takes　refuge　in　Lamarckism。　　In
relation　to　the　manner　in　which　the　eyes　of　soles；　turbots；　and
other　flat…fish　travel　round　the　head　so　as　to　become　in　the　end
unsymmetrically　placed；　he　says：…

〃The　eyes　of　these　fish　are　curiously　distorted　in　order　that　both
eyes　may　be　upon　the　upper　side；　where　alone　they　would　be　of　any
use。　。　。　。　Now　if　we　suppose　this　process；　which　in　the　young　is
completed　in　a　few　days　or　weeks；　to　have　been　spread　over　thousands
of　generations　during　the　development　of　these　fish；　those　usually
surviving　WHOSE　EYES　RETAINED　MORE　AND　MORE　OF　THE　POSITION　INTO
WHICH　THE　YOUNG　FISH　TRIED　TO　TWIST　THEM　＇italics　mine＇；　the　change
becomes　intelligible。〃　｛24｝　　When　it　was　said　by　Professor　Ray
Lankesterwho　knows　as　well　as　most　people　what　Lamarck　taught
that　this　was　〃flat　Lamarckism；〃　Mr。　Wallace　rejoined　that　it　was
the　survival　of　the　modified　individuals　that　did　it　all；　not　the
efforts　of　the　young　fish　to　twist　their　eyes；　and　the　transmission
to　descendants　of　the　effects　of　those　efforts。　　But　this；　as　I　said
in　my　book；　〃Evolution；　Old　and　New；〃　｛25｝　is　like　saying　that
horses　are　swift　runners；　not　by　reason　of　the　causes；　whatever　they
were；　that　occasioned　the　direct　line　of　their　progenitors　to　vary
towards　ever　greater　and　greater　swiftness；　but　because　their　more
slow…going　uncles　and　aunts　go　away。　　Plain　people　will　prefer　to
say　that　the　main　cause　of　any　accumulation　of　favourable
modifications　consists　rather　in　that　which　brings　about　the　initial
variations；　and　in　the　fact　that　these　can　be　inherited　at　all；　than
in　the　fact　that　the　unmodified　individuals　were　not　successful。
People　do　not　become　rich　because　the　poor　in　large　numbers　go　away；
but　because　they　have　been　lucky；　or　provident；　or　more　commonly
both。　　If　they　would　keep　their　wealth　when　they　have　made　it　they
must　exclude　luck　thenceforth　to　the　utmost　of　their　power；　and
their　children　must　follow　their　example；　or　they　will　soon　lose
their　money。　　The　fact　that　the　weaker　go　to　the　wall　does　not　bring
about　the　greater　strength　of　the　stronger；　it　is　the　consequence　of
this　last　and　not　the　causeunless；　indeed；　it　be　contended　that　a
knowledge　that　the　weak　go　to　the　wall　stimulates　the　strong　to
exertions　which　they　would　not　otherwise　so　make；　and　that　these
exertions　produce　inheritable　modifications。　　Even　in　this　case；
however；　it　would　be　the　exertions；　or　use　and　disuse；　that　would　be
the　main　agents　in　the　modification。　　But　it　is　not　often　that　Mr。
Wallace　thus　backslides。　　His　present　position　is　that　acquired　（as
distinguished　from　congenital）　modifications　are　not　inherited　at
all。　　He　does　not　indeed　put　his　faith　prominently　forward　and　pin
himself　to　it　as　plainly　as　could　be　wished；　but　under　the　heading；
〃The　Non…Heredity　of　Acquired　Characters；〃　he　writes　as　follows　on
p。　440　of　his　recent　work　in　reference　to　Professor　Weismann's
Theory　of　Heredity：…

〃Certain　observations　on　the　embryology　of　the　lower　animals　are
held　to　afford　direct　proof　of　this　theory　of　heredity；　but　they　are
too　technical　to　be　made　clear　to　ordinary　readers。　　A　logical
result　of　the　theory　is　the　impossibility　of　the　transmission　of
acquired　characters；　since　the　molecular　structure　of　the　germ…plasm
is　already　determined　within　the　embryo；　and　Weismann　holds　that
there　are　no　facts　which　really　prove　that　acquired　characters　can
be　inherited；　although　their　inheritance　has；　by　most　writers；　been
considered　so　probable　as　hardly　to　stand　in　need　of　direct　proof。

〃We　have　already　seen　in　the　earlier　part　of　this　chapter　that　many
instances　of　change；　imputed　to　the　inheritance　of　acquired
variations；　are　really　cases　of　selection。〃

And　the　rest　of　the　remarks　tend　to　convey　the　impression　that　Mr。
Wallace　adopts　Professor　Weismann's　view；　but；　curiously　enough；
though　I　have　gone　through　Mr。　Wallace's　book　with　a　special　view　to
this　particular　point；　I　have　not　been　able　to　find　him　definitely
committing　himself　either　to　the　assertion　that　acquired
modifications　never　are　inherited；　or　that　they　sometimes　are　so。
It　is　abundantly　laid　down　that　Mr。　Darwin　laid　too　much　stress　on
use　and　disuse；　and　a　residuary　impression　is　left　that　Mr。　Wallace
is　endorsing　Professor　Weismann's