the perpetuation of living beings-第3章

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nourishment；　and　so　on；　you　may　by…and…by　convert　single　flowers　into
double　flowers；　and　make　thorns　shoot　out　into　branches。　　You　may
thicken　or　make　various　modifications　in　the　shape　of　the　fruit。　　In
animals；　too；　you　may　produce　analogous　changes　in　this　way；　as　in　the
case　of　that　deep　bronze　colour　which　persons　rarely　lose　after　having
passed　any　length　of　time　in　tropical　countries。　　You　may　also　alter
the　development　of　the　muscles　very　much；　by　dint　of　training；　all　the
world　knows　that　exercise　has　a　great　effect　in　this　way；　we　always
expect　to　find　the　arm　of　a　blacksmith　hard　and　wiry；　and　possessing　a
large　development　of　the　brachial　muscles。　　No　doubt　training；　which　is
one　of　the　forms　of　external　conditions；　converts　what　are　originally
only　instructions；　teachings；　into　habits；　or；　in　other　words；　into
organizations；　to　a　great　extent；　but　this　second　cause　of　variation
cannot　be　considered　to　be　by　any　means　a　large　one。　　The　third　cause
that　I　have　to　mention；　however；　is　a　very　extensive　one。　　It　is　one
that；　for　want　of　a　better　name；　has　been　called　〃spontaneous
variation；〃　which　means　that　when　we　do　not　know　anything　about　the
cause　of　phenomena；　we　call　it　spontaneous。　　In　the　orderly　chain　of
causes　and　effects　in　this　world；　there　are　very　few　things　of　which　it
can　be　said　with　truth　that　they　are　spontaneous。　Certainly　not　in
these　physical　matters；in　these　there　is　nothing　of　the
kind；everything　depends　on　previous　conditions。　　But　when　we　cannot
trace　the　cause　of　phenomena；　we　call　them　spontaneous。

Of　these　variations；　multitudinous　as　they　are；　but　little　is　known　with
perfect　accuracy。　　I　will　mention　to　you　some　two　or　three　cases；
because　they　are　very　remarkable　in　themselves；　and　also　because　I
shall　want　to　use　them　afterwards。　　Reaumur；　a　famous　French　naturalist；
a　great　many　years　ago；　in　an　essay　which　he　wrote　upon　the　art　of
hatching　chickens；which　was　indeed　a　very　curious　essay；had
occasion　to　speak　of　variations　and　monstrosities。　　One　very　remarkable
case　had　come　under　his　notice　of　a　variation　in　the　form　of　a　human
member；　in　the　person　of　a　Maltese；　of　the　name　of　Gratio　Kelleia；　who
was　born　with　six　fingers　upon　each　hand；　and　the　like　number　of　toes
to　each　of　his　feet。　　That　was　a　case　of　spontaneous　variation。　　Nobody
knows　why　he　was　born　with　that　number　of　fingers　and　toes；　and　as　we
don't　know；　we　call　it　a　case　of　〃spontaneous〃　variation。　　There　is
another　remarkable　case　also。　　I　select　these；　because　they　happen　to
have　been　observed　and　noted　very　carefully　at　the　time。　　It　frequently
happens　that　a　variation　occurs；　but　the　persons　who　notice　it　do　not
take　any　care　in　noting　down　the　particulars；　until　at　length；　when
inquiries　come　to　be　made；　the　exact　circumstances　are　forgotten；　and
hence；　multitudinous　as　may　be　such　〃spontaneous〃　variations；　it　is
exceedingly　difficult　to　get　at　the　origin　of　them。

The　second　case　is　one　of　which　you　may　find　the　whole　details　in　the
〃Philosophical　Transactions〃　for　the　year　1813；　in　a　paper　communicated
by　Colonel　Humphrey　to　the　President　of　the　Royal　Society；〃On　a　new
Variety　in　the　Breed　of　Sheep；〃　giving　an　account　of　a　very　remarkable
breed　of　sheep；　which　at　one　time　was　well　known　in　the　northern　states
of　America；　and　which　went　by　the　name　of　the　Ancon　or　the　Otter　breed
of　sheep。　　In　the　year　1791；　there　was　a　farmer　of　the　name　of　Seth
Wright　in　Massachusetts；　who　had　a　flock　of　sheep；　consisting　of　a　ram
and；　I　think；　of　some　twelve　or　thirteen　ewes。　　Of　this　flock　of　ewes；
one　at　the　breeding…time　bore　a　lamb　which　was　very　singularly　formed；
it　had　a　very　long　body；　very　short　legs；　and　those　legs　were　bowed！　　I
will　tell　you　by…and…by　how　this　singular　variation　in　the　breed　of
sheep　came　to　be　noted；　and　to　have　the　prominence　that　it　now　has。　For
the　present；　I　mention　only　these　two　cases；　but　the　extent　of　variation
in　the　breed　of　animals　is　perfectly　obvious　to　any　one　who　has　studied
natural　history　with　ordinary　attention；　or　to　any　person　who　compares
animals　with　others　of　the　same　kind。　　It　is　strictly　true　that　there
are　never　any　two　specimens　which　are　exactly　alike；　however　similar；
they　will　always　differ　in　some　certain　particular。

Now　let　us　go　back　to　Atavism；to　the　hereditary　tendency　I　spoke　of。
What　will　come　of　a　variation　when　you　breed　from　it；　when　Atavism
comes；　if　I　may　say　so；　to　intersect　variation？　The　two　cases　of　which
I　have　mentioned　the　history；　give　a　most　excellent　illustration　of
what　occurs。　　Gratio　Kelleia；　the　Maltese；　married　when　he　was
twenty…two　years　of　age；　and；　as　I　suppose　there　were　no　six…fingered
ladies　in　Malta；　he　married　an　ordinary　five…fingered　person。　　The
result　of　that　marriage　was　four　children；　the　first；　who　was　christened
Salvator；　had　six　fingers　and　six　toes；　like　his　father；　the　second　was
George；　who　had　five　fingers　and　toes；　but　one　of　them　was　deformed；
showing　a　tendency　to　variation；　the　third　was　Andre；　he　had　five
fingers　and　five　toes；　quite　perfect；　the　fourth　was　a　girl；　Marie；　she
had　five　fingers　and　five　toes；　but　her　thumbs　were　deformed；　showing　a
tendency　toward　the　sixth。

These　children　grew　up；　and　when　they　came　to　adult　years；　they　all
married；　and　of　course　it　happened　that　they　all　married　five…fingered
and　five…toed　persons。　　Now　let　us　see　what　were　the　results。　　Salvator
had　four　children；　they　were　two　boys；　a　girl；　and　another　boy；　the
first　two　boys　and　the　girl　were　six…fingered　and　six…toed　like　their
grandfather；　the　fourth　boy　had　only　five　fingers　and　five　toes。　George
had　only　four　children；　there　were　two　girls　with　six　fingers　and　six
toes；　there　was　one　girl　with　six　fingers　and　five　toes　on　the　right
side；　and　five　fingers　and　five　toes　on　the　left　side；　so　that　she　was
half　and　half。　　The　last；　a　boy；　had　five　fingers　and　five　toes。　　The
third；　Andre；　you　will　recollect；　was　perfectly　well…formed；　and　he　had
many　children　whose　hands　and　feet　were　all　regularly　developed。　　Marie；
the　last；　who；　of　course；　married　a　man　who　had　only　five　fingers；　had
four　children；　the　first；　a　boy；　was　born　with　six　toes；　but　the　other
three　were　normal。

Now　observe　what　very　extraordinary　phenomena　are　presented　here。　　You
have　an　accidental　variation　arising　from　what　you　may　call　a
monstrosity；　you　have　that　monstrosity　tendency　or　variation　diluted　in
the　first　instance　by　an　admixture　with　a　female　of　normal　construction；
and　you　would　naturally　expect　that；　in　the　results　of　such　an　union；
the　monstrosity；　if　repeated；　would　be　in　equal　proportion　with　the
normal　type；　that　is　to　say；　that　the　children　would　be　half　and　half；
some　taking　the　peculiarity　of　the　father；　and　the　others　being　of　the
purely　normal　type　of　the　mother；　but　you　see　we　have　a　great
preponderance　of　the　abnormal　type。　Well；　this　comes　to　be　mixed　once
more　with　the　pure；　the　normal　type；　and　the　abnormal　is　again　produced
in　large　proportion；　notwithstanding　the　second　dilution。　　Now　what
would　have　happened　if　these　abnormal　types　had　intermarried　with　each
other；　that　is　to　say；　suppose　the　two　boys　of　Salvator　had　taken　it
into　their　heads　to　marry　their　first　cousins；　the　two　first　girls　of
George；　their　uncle？　　You　will　remember　that　these　are　all　of　the
abnormal　type　of　their　grandfather。　　The　result　would　probably　have
been；　that　their　offspring　would　have　been　in　every　case　a　further
development　of　that　abnormal　type。　　You　see　it　is　only　in　the　fourth；
in　the　person　of　Marie；　that　the　tendency；　when　it　appears　but　slightly
in　the　second　generation；　is　washed　out　in　the　third；　while　the　progeny
of　Andre；　who　escaped　in　the　first　instance；　escape　altogether。

We　have　in　this　case　a　good　example　of　nature's　tendency　to　the
perpetuation　of　a　variation。　Here　it　is　certainly　a　variation　which
carried　with　it　no　use　or　benefit；　and　yet　you　see　the　tendency　to
perpetuation　may　be　so　strong；　that；　notwithstanding　a　great　admixture
of　pure　blood；　the　variety　continues　itself　up　to　the　third　generation；
which　is　largely　marked　with　it。　In　this　case；　as　I　have　said；　there
was　no　means　of　the　second　generation　inter