SurelyifdisusecanbecreditedwiththevastpowersinvolvedinMr。Darwin’sstatementthatithasprobably\"beenthemainagentinrenderingorgansrudimentary，\"nolimitsareassignabletotheaccumulatedeffectsofhabit，providedtheeffectsofhabit，oruseanddisuse，aresupposed，asMr。Darwinsupposedthem，tobeinheritableatall。DarwinianshaveatlengthwokeuptothedilemmainwhichtheyareplacedbythemannerinwhichMr。Darwintriedtositonthetwostoolsofuseanddisuse，andnaturalselectionofaccidentalvariations，atthesametime。TheknellofCharles-DarwinismisrunginMr。Wallace’spresentbook，andinthegeneralperceptiononthepartofbiologiststhatwemusteitherassigntouseanddisusesuchapredominantshareinmodificationastomakeitthefeaturemostpropertobeinsistedon，ordenythatthemodifications，whetherofmindorbody，acquiredduringasinglelifetime，areevertransmittedatall。Iftheycanbeinheritedatall，theycanbeaccumulated。Iftheycanbeaccumulatedatall，theycanbeso，foranythingthatappearstothecontrary，totheextentofthespecificandgenericdifferenceswithwhichwearesurrounded。Theonlythingtodoistopluckthemoutrootandbranch：theyareasacancerwhich，ifthesmallestfibrebeleftunexcised，willgrowagain，andkillanysystemontowhichitisallowedtofasten。Mr。Wallace，therefore，maywellbeexcusedifhecastslongingeyestowardsWeismannism。
AndwhatwasMr。Darwin’ssystem？Whocanmakeheadortailoftheinextricablemuddleinwhichheleftit？The\"OriginofSpecies\"initslatestshapeisthereductionofhedgingtoanabsurdity。HowdidMr。Darwinhimselfleaveitinthelastchapterofthelasteditionofthe\"OriginofSpecies\"？Hewrote：-
\"Ihavenowrecapitulatedthefactsandconsiderationswhichhavethoroughlyconvincedmethatspecieshavebeenmodifiedduringalongcourseofdescent。Thishasbeeneffectedchieflythroughthenaturalselectionofnumerous，successive，slight，favourablevariations；aidedinanimportantmannerbytheinheritedeffectsoftheuseanddisuseofparts，andinanunimportantmanner——thatis，inrelationtoadaptivestructureswhetherpastorpresent——bythedirectactionofexternalconditions，andbyvariationswhichseemtousinourignorancetoarisespontaneously。ItappearsthatI
formerlyunderratedthefrequencyandvalueoftheselatterformsofvariation，asleadingtopermanentmodificationsofstructureindependentlyofnaturalselection。\"
The\"numerous，successive，slight，favourablevariations\"abovereferredtoareintendedtobefortuitous，accidental，spontaneous。