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s¡¡which¡¡it¡¡connects£»¡¡consequently¡¡the¡¡two¡¡latter£»¡¡during¡¡the¡¡course¡¡of¡¡further¡¡modification£»¡¡from¡¡existing¡¡in¡¡greater¡¡numbers£»¡¡will¡¡have¡¡a¡¡great¡¡advantage¡¡over¡¡the¡¡less¡¡numerous¡¡intermediate¡¡variety£»¡¡and¡¡will¡¡thus¡¡generally¡¡succeed¡¡in¡¡supplanting¡¡and¡¡exterminating¡¡it¡£¡¡
We¡¡have¡¡seen¡¡in¡¡this¡¡chapter¡¡how¡¡cautious¡¡we¡¡should¡¡be¡¡in¡¡concluding¡¡that¡¡the¡¡most¡¡different¡¡habits¡¡of¡¡life¡¡could¡¡not¡¡graduate¡¡into¡¡each¡¡other£»¡¡that¡¡a¡¡bat£»¡¡for¡¡instance£»¡¡could¡¡not¡¡have¡¡been¡¡formed¡¡by¡¡natural¡¡selection¡¡from¡¡an¡¡animal¡¡which¡¡at¡¡first¡¡could¡¡only¡¡glide¡¡through¡¡the¡¡air¡£¡¡
We¡¡have¡¡seen¡¡that¡¡a¡¡species¡¡may¡¡under¡¡new¡¡conditions¡¡of¡¡life¡¡change¡¡its¡¡habits£»¡¡or¡¡have¡¡diversified¡¡habits£»¡¡with¡¡some¡¡habits¡¡very¡¡unlike¡¡those¡¡of¡¡its¡¡nearest¡¡congeners¡£¡¡Hence¡¡we¡¡can¡¡understand¡¡bearing¡¡in¡¡mind¡¡that¡¡each¡¡organic¡¡being¡¡is¡¡trying¡¡to¡¡live¡¡wherever¡¡it¡¡can¡¡live£»¡¡how¡¡it¡¡has¡¡arisen¡¡that¡¡there¡¡are¡¡upland¡¡geese¡¡with¡¡webbed¡¡feet£»¡¡ground¡¡woodpeckers£»¡¡diving¡¡thrushes£»¡¡and¡¡petrels¡¡with¡¡the¡¡habits¡¡of¡¡auks¡£¡¡
Although¡¡the¡¡belief¡¡that¡¡an¡¡organ¡¡so¡¡perfect¡¡as¡¡the¡¡eye¡¡could¡¡have¡¡been¡¡formed¡¡by¡¡natural¡¡selection£»¡¡is¡¡more¡¡than¡¡enough¡¡to¡¡stagger¡¡any¡¡one£»¡¡yet¡¡in¡¡the¡¡case¡¡of¡¡any¡¡organ£»¡¡if¡¡we¡¡know¡¡of¡¡a¡¡long¡¡series¡¡of¡¡gradations¡¡in¡¡complexity£»¡¡each¡¡good¡¡for¡¡its¡¡possessor£»¡¡then£»¡¡under¡¡changing¡¡conditions¡¡of¡¡life£»¡¡there¡¡is¡¡no¡¡logical¡¡impossibility¡¡in¡¡the¡¡acquirement¡¡of¡¡any¡¡conceivable¡¡degree¡¡of¡¡perfection¡¡through¡¡natural¡¡selection¡£¡¡In¡¡the¡¡cases¡¡in¡¡which¡¡we¡¡know¡¡of¡¡no¡¡intermediate¡¡or¡¡transitional¡¡states£»¡¡we¡¡should¡¡be¡¡very¡¡cautious¡¡in¡¡concluding¡¡that¡¡none¡¡could¡¡have¡¡existed£»¡¡for¡¡the¡¡homologies¡¡of¡¡many¡¡organs¡¡and¡¡their¡¡intermediate¡¡states¡¡show¡¡that¡¡wonderful¡¡metamorphoses¡¡in¡¡function¡¡are¡¡at¡¡least¡¡possible¡£¡¡For¡¡instance£»¡¡a¡¡swim¡­bladder¡¡has¡¡apparently¡¡been¡¡converted¡¡into¡¡an¡¡air¡­breathing¡¡lung¡£¡¡The¡¡same¡¡organ¡¡having¡¡performed¡¡simultaneously¡¡very¡¡different¡¡functions£»¡¡and¡¡then¡¡having¡¡been¡¡specialised¡¡for¡¡one¡¡function£»¡¡and¡¡two¡¡very¡¡distinct¡¡organs¡¡having¡¡performed¡¡at¡¡the¡¡same¡¡time¡¡the¡¡same¡¡function£»¡¡the¡¡one¡¡having¡¡been¡¡perfected¡¡whilst¡¡aided¡¡by¡¡the¡¡other£»¡¡must¡¡often¡¡have¡¡largely¡¡facilitated¡¡transitions¡£¡¡
We¡¡are¡¡far¡¡too¡¡ignorant£»¡¡in¡¡almost¡¡every¡¡case£»¡¡to¡¡be¡¡enabled¡¡to¡¡assert¡¡that¡¡any¡¡part¡¡or¡¡organ¡¡is¡¡so¡¡unimportant¡¡for¡¡the¡¡welfare¡¡of¡¡a¡¡species£»¡¡that¡¡modifications¡¡in¡¡its¡¡structure¡¡could¡¡not¡¡have¡¡been¡¡slowly¡¡accumulated¡¡by¡¡means¡¡of¡¡natural¡¡selection¡£¡¡But¡¡we¡¡may¡¡confidently¡¡believe¡¡that¡¡many¡¡modifications£»¡¡wholly¡¡due¡¡to¡¡the¡¡laws¡¡of¡¡growth£»¡¡and¡¡at¡¡first¡¡in¡¡no¡¡way¡¡advantageous¡¡to¡¡a¡¡species£»¡¡have¡¡been¡¡subsequently¡¡taken¡¡advantage¡¡of¡¡by¡¡the¡¡still¡¡further¡¡modified¡¡descendants¡¡of¡¡this¡¡species¡£¡¡We¡¡may£»¡¡also£»¡¡believe¡¡that¡¡a¡¡part¡¡formerly¡¡of¡¡high¡¡importance¡¡has¡¡often¡¡been¡¡retained¡¡£¨as¡¡the¡¡tail¡¡of¡¡an¡¡aquatic¡¡animal¡¡by¡¡its¡¡terrestrial¡¡descendants£©£»¡¡though¡¡it¡¡has¡¡become¡¡of¡¡such¡¡small¡¡importance¡¡that¡¡it¡¡could¡¡not£»¡¡in¡¡its¡¡present¡¡state£»¡¡have¡¡been¡¡acquired¡¡by¡¡natural¡¡selection£»¡¡a¡¡power¡¡which¡¡acts¡¡solely¡¡by¡¡the¡¡preservation¡¡of¡¡profitable¡¡variations¡¡in¡¡the¡¡struggle¡¡for¡¡life¡£¡¡
Natural¡¡selection¡¡will¡¡produce¡¡nothing¡¡in¡¡one¡¡species¡¡for¡¡the¡¡exclusive¡¡good¡¡or¡¡injury¡¡of¡¡another£»¡¡though¡¡it¡¡may¡¡well¡¡produce¡¡parts£»¡¡organs£»¡¡and¡¡excretions¡¡highly¡¡useful¡¡or¡¡even¡¡indispensable£»¡¡or¡¡highly¡¡injurious¡¡to¡¡another¡¡species£»¡¡but¡¡in¡¡all¡¡cases¡¡at¡¡the¡¡same¡¡time¡¡useful¡¡to¡¡the¡¡owner¡£¡¡Natural¡¡selection¡¡in¡¡each¡¡well¡­stocked¡¡country£»¡¡must¡¡act¡¡chiefly¡¡through¡¡the¡¡competition¡¡of¡¡the¡¡inhabitants¡¡one¡¡with¡¡another£»¡¡and¡¡consequently¡¡will¡¡produce¡¡perfection£»¡¡or¡¡strength¡¡in¡¡the¡¡battle¡¡for¡¡life£»¡¡only¡¡according¡¡to¡¡the¡¡standard¡¡of¡¡that¡¡country¡£¡¡Hence¡¡the¡¡inhabitants¡¡of¡¡one¡¡country£»¡¡generally¡¡the¡¡smaller¡¡one£»¡¡will¡¡often¡¡yield£»¡¡as¡¡we¡¡see¡¡they¡¡do¡¡yield£»¡¡to¡¡the¡¡inhabitants¡¡of¡¡another¡¡and¡¡generally¡¡larger¡¡country¡£¡¡For¡¡in¡¡the¡¡larger¡¡country¡¡there¡¡will¡¡have¡¡existed¡¡more¡¡individuals£»¡¡and¡¡more¡¡diversified¡¡forms£»¡¡and¡¡the¡¡competition¡¡will¡¡have¡¡been¡¡severer£»¡¡and¡¡thus¡¡the¡¡standard¡¡of¡¡perfection¡¡will¡¡have¡¡been¡¡rendered¡¡higher¡£¡¡Natural¡¡selection¡¡will¡¡not¡¡necessarily¡¡produce¡¡absolute¡¡perfection£»¡¡nor£»¡¡as¡¡far¡¡as¡¡we¡¡can¡¡judge¡¡by¡¡our¡¡limited¡¡faculties£»¡¡can¡¡absolute¡¡perfection¡¡be¡¡everywhere¡¡found¡£¡¡
On¡¡the¡¡theory¡¡of¡¡natural¡¡selection¡¡we¡¡can¡¡clearly¡¡understand¡¡the¡¡full¡¡meaning¡¡of¡¡that¡¡old¡¡canon¡¡in¡¡natural¡¡history£»¡¡'Natura¡¡non¡¡facit¡¡saltum¡£'¡¡This¡¡canon£»¡¡if¡¡we¡¡look¡¡only¡¡to¡¡the¡¡present¡¡inhabitants¡¡of¡¡the¡¡world£»¡¡is¡¡not¡¡strictly¡¡correct£»¡¡but¡¡if¡¡we¡¡include¡¡all¡¡those¡¡of¡¡past¡¡times£»¡¡it¡¡must¡¡by¡¡my¡¡theory¡¡be¡¡strictly¡¡true¡£¡¡
It¡¡is¡¡generally¡¡acknowledged¡¡that¡¡all¡¡organic¡¡beings¡¡have¡¡been¡¡formed¡¡on¡¡two¡¡great¡¡laws¡¡Unity¡¡of¡¡Type£»¡¡and¡¡the¡¡Conditions¡¡of¡¡Existence¡£¡¡By¡¡unity¡¡of¡¡type¡¡is¡¡meant¡¡that¡¡fundamental¡¡agreement¡¡in¡¡structure£»¡¡which¡¡we¡¡see¡¡in¡¡organic¡¡beings¡¡of¡¡the¡¡same¡¡class£»¡¡and¡¡which¡¡is¡¡quite¡¡independent¡¡of¡¡their¡¡habits¡¡of¡¡life¡£¡¡On¡¡my¡¡theory£»¡¡unity¡¡of¡¡type¡¡is¡¡explained¡¡by¡¡unity¡¡of¡¡descent¡£¡¡The¡¡expression¡¡of¡¡conditions¡¡of¡¡existence£»¡¡so¡¡often¡¡insisted¡¡on¡¡by¡¡the¡¡illustrious¡¡Cuvier£»¡¡is¡¡fully¡¡embraced¡¡by¡¡the¡¡principle¡¡of¡¡natural¡¡selection¡£¡¡For¡¡natural¡¡selection¡¡acts¡¡by¡¡either¡¡now¡¡adapting¡¡the¡¡varying¡¡parts¡¡of¡¡each¡¡being¡¡to¡¡its¡¡organic¡¡and¡¡inorganic¡¡conditions¡¡of¡¡life£»¡¡or¡¡by¡¡having¡¡adapted¡¡them¡¡during¡¡long¡­past¡¡periods¡¡of¡¡time£º¡¡the¡¡adaptations¡¡being¡¡aided¡¡in¡¡some¡¡cases¡¡by¡¡use¡¡and¡¡disuse£»¡¡being¡¡slightly¡¡affected¡¡by¡¡the¡¡direct¡¡action¡¡of¡¡the¡¡external¡¡conditions¡¡of¡¡life£»¡¡and¡¡being¡¡in¡¡all¡¡cases¡¡subjected¡¡to¡¡the¡¡several¡¡laws¡¡of¡¡growth¡£¡¡Hence£»¡¡in¡¡fact£»¡¡the¡¡law¡¡of¡¡the¡¡Conditions¡¡of¡¡Existence¡¡is¡¡the¡¡higher¡¡law£»¡¡as¡¡it¡¡includes£»¡¡through¡¡the¡¡inheritance¡¡of¡¡former¡¡adaptations£»¡¡that¡¡of¡¡Unity¡¡of¡¡Type¡£¡¡¡¡
Chapter¡¡7¡¡¡­¡¡Instinct

THE¡¡subject¡¡of¡¡instinct¡¡might¡¡have¡¡been¡¡worked¡¡into¡¡the¡¡previous¡¡chapters£»¡¡but¡¡I¡¡have¡¡thought¡¡that¡¡it¡¡would¡¡be¡¡more¡¡convenient¡¡to¡¡treat¡¡the¡¡subject¡¡separately£»¡¡especially¡¡as¡¡so¡¡wonderful¡¡an¡¡instinct¡¡as¡¡that¡¡of¡¡the¡¡hive¡­bee¡¡making¡¡its¡¡cells¡¡will¡¡probably¡¡have¡¡occurred¡¡to¡¡many¡¡readers£»¡¡as¡¡a¡¡difficulty¡¡sufficient¡¡to¡¡overthrow¡¡my¡¡whole¡¡theory¡£¡¡I¡¡must¡¡premise£»¡¡that¡¡I¡¡have¡¡nothing¡¡to¡¡do¡¡with¡¡the¡¡origin¡¡of¡¡the¡¡primary¡¡mental¡¡powers£»¡¡any¡¡more¡¡than¡¡I¡¡have¡¡with¡¡that¡¡of¡¡life¡¡itself¡£¡¡We¡¡are¡¡concerned¡¡only¡¡with¡¡the¡¡diversities¡¡of¡¡instinct¡¡and¡¡of¡¡the¡¡other¡¡mental¡¡qualities¡¡of¡¡animals¡¡within¡¡the¡¡same¡¡class¡£¡¡
I¡¡will¡¡not¡¡attempt¡¡any¡¡definition¡¡of¡¡instinct¡£¡¡It¡¡would¡¡be¡¡easy¡¡to¡¡show¡¡that¡¡several¡¡distinct¡¡mental¡¡actions¡¡are¡¡commonly¡¡embraced¡¡by¡¡this¡¡term£»¡¡but¡¡every¡¡one¡¡understands¡¡what¡¡is¡¡meant£»¡¡when¡¡it¡¡is¡¡said¡¡that¡¡instinct¡¡impels¡¡the¡¡cuckoo¡¡to¡¡migrate¡¡and¡¡to¡¡lay¡¡her¡¡eggs¡¡in¡¡other¡¡birds'¡¡nests¡£¡¡An¡¡action£»¡¡which¡¡we¡¡ourselves¡¡should¡¡require¡¡experience¡¡to¡¡enable¡¡us¡¡to¡¡perform£»¡¡when¡¡performed¡¡by¡¡an¡¡animal£»¡¡more¡¡especially¡¡by¡¡a¡¡very¡¡young¡¡one£»¡¡without¡¡any¡¡experience£»¡¡and¡¡when¡¡performed¡¡by¡¡many¡¡individuals¡¡in¡¡the¡¡same¡¡way£»¡¡without¡¡their¡¡knowing¡¡for¡¡what¡¡purpose¡¡it¡¡is¡¡performed£»¡¡is¡¡usually¡¡said¡¡to¡¡be¡¡instinctive¡£¡¡But¡¡I¡¡could¡¡show¡¡that¡¡none¡¡of¡¡these¡¡characters¡¡of¡¡instinct¡¡are¡¡universal¡£¡¡A¡¡little¡¡dose£»¡¡as¡¡Pierre¡¡Huber¡¡expresses¡¡it£»¡¡of¡¡judgment¡¡or¡¡reason£»¡¡often¡¡comes¡¡into¡¡play£»¡¡even¡¡in¡¡animals¡¡very¡¡low¡¡in¡¡the¡¡scale¡¡of¡¡nature¡£¡¡
Frederick¡¡Cuvier¡¡and¡¡several¡¡of¡¡the¡¡older¡¡metaphysicians¡¡have¡¡compared¡¡instinct¡¡with¡¡habit¡£¡¡This¡¡comparison¡¡gives£»¡¡I¡¡think£»¡¡a¡¡remarkably¡¡accurate¡¡notion¡¡of¡¡the¡¡frame¡¡of¡¡mind¡¡under¡¡which¡¡an¡¡instinctive¡¡action¡¡is¡¡performed£»¡¡but¡¡not¡¡of¡¡its¡¡origin¡£¡¡How¡¡unconsciously¡¡many¡¡habitual¡¡actions¡¡are¡¡performed£»¡¡indeed¡¡not¡¡rarely¡¡in¡¡direct¡¡opposition¡¡to¡¡our¡¡conscious¡¡will£¡¡¡yet¡¡they¡¡may¡¡be¡¡modified¡¡by¡¡the¡¡will¡¡or¡¡reason¡£¡¡Habits¡¡easily¡¡become¡¡associated¡¡with¡¡other¡¡habits£»¡¡and¡¡with¡¡certain¡¡periods¡¡of¡¡time¡¡and¡¡states¡¡of¡¡the¡¡body¡£¡¡When¡¡once¡¡acquired£»¡¡they¡¡often¡¡remain¡¡constant¡¡throughout¡¡life¡£¡¡Several¡¡other¡¡points¡¡of¡¡resemblance¡¡between¡¡instincts¡¡and¡¡habits¡¡could¡¡be¡¡pointed¡¡out¡£¡¡As¡¡in¡¡repeating¡¡a¡¡well¡­known¡¡song£»¡¡so¡¡in¡¡instincts£»¡¡one¡¡action¡¡follows¡¡another¡¡by¡¡a¡¡sort¡¡of¡¡rhythm£»¡¡if¡¡a¡¡person¡¡be¡¡interrupted¡¡in¡¡a¡¡song£»¡¡or¡¡in¡¡repeating¡¡anything¡¡by¡¡rote£»¡¡he¡¡is¡¡generally¡¡forced¡¡to¡¡go¡¡back¡¡to¡¡recover¡¡the¡¡habitual¡¡train¡¡of¡¡thought£º¡¡so¡¡P¡£¡¡Huber¡¡found¡¡it¡¡was¡¡with¡¡a¡¡caterpillar£»¡¡which¡¡makes¡¡a¡¡very¡¡complicated¡¡hammock£»¡¡for¡¡if¡¡he¡¡took¡¡a¡¡caterpillar¡¡which¡¡had¡¡completed¡¡its¡¡hammock¡¡up¡¡to£»¡¡say£»¡¡the¡¡sixth¡¡stage¡¡of¡¡construction£»¡¡and¡¡put¡¡it¡¡into¡¡a¡¡hammock¡¡completed¡¡up¡¡only¡¡to¡¡the¡¡third¡¡stage£»¡¡the¡¡caterpillar¡¡simply¡¡re¡­performed¡¡the¡¡fourth£»¡¡fifth£»¡¡and¡¡sixth¡¡stages¡¡of¡¡construction¡£¡¡If£»¡¡however£»¡¡a¡¡caterpillar¡¡were¡¡taken¡¡out¡¡of¡¡a¡¡hammock¡¡made¡¡up£»¡¡for¡¡instance£»¡¡to¡¡the¡¡third¡¡stage£»¡¡and¡¡were¡¡put¡¡into¡¡one¡¡finished¡¡up¡¡to¡¡the¡¡sixth¡¡stage£»¡¡so¡¡that¡¡much¡¡of¡¡its¡¡work¡¡was¡¡already¡¡done¡¡for¡¡it£»¡¡far¡¡from¡¡feeling¡¡the¡¡benefit¡¡of¡¡this£»¡¡it¡¡was¡¡much¡¡embarrassed£»¡¡and£»¡¡in¡¡order¡¡to¡¡complete¡¡its¡¡hammock£»¡¡seemed¡¡forced¡¡to¡¡start¡¡from¡¡the¡¡third¡¡stage£»¡¡where¡¡it¡¡had¡¡left¡¡off£»¡¡and¡¡thus¡¡tried¡¡to¡¡complete¡¡the¡¡already¡¡finished¡¡work¡£¡¡
If¡¡we¡¡suppose¡¡any¡¡habitual¡¡action¡¡to¡¡become¡¡inherited¡¡and¡¡I¡¡think¡¡it¡¡can¡¡be¡¡shown¡¡that¡¡this¡¡does¡¡sometimes¡¡happen¡¡then¡¡the¡¡resemblance¡¡between¡¡what¡¡originally¡¡was¡¡a¡¡habit¡¡and¡¡an¡¡instinct¡¡becomes¡¡so¡¡close¡¡as¡¡not¡¡to¡¡be¡¡distinguished¡£¡¡If¡¡Mozart£»¡¡instead¡¡of¡¡playing¡¡the¡¡pianoforte¡¡at¡¡three¡¡years¡¡old¡¡with¡¡wonderfully¡¡little¡¡practice£»¡¡had¡¡played¡¡a¡¡tune¡¡with¡¡no¡¡practice¡¡at¡¡all£»¡¡be¡¡might¡¡truly¡¡be¡¡said¡¡to¡¡have¡¡done¡¡so¡¡instinctively¡£¡¡But¡¡it¡¡would¡¡be¡¡the¡¡most¡¡serious¡¡error¡¡to¡¡suppose¡¡that¡¡the¡¡greater¡¡number¡¡of¡¡instincts¡¡have¡¡been¡¡acquired¡¡by¡¡habit¡¡in¡¡one¡¡generation£»¡¡and¡¡then¡¡transmitted¡¡by¡¡inheritance¡¡to¡¡succeeding¡¡generations¡£¡¡It¡¡can¡¡be¡¡clearly¡¡shown¡¡that¡¡the¡¡most¡¡wonderful¡¡instincts¡¡with¡¡which¡¡we¡¡are¡¡acquainted£»¡¡namely£»¡¡those¡¡of¡¡the¡¡hive¡­bee¡¡and¡¡of¡¡many¡¡ants£»¡¡c

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