Asthefactsstand, itappearsthat, whilesometertiaryformsareessentiallyundistinguishablefromexistingones, othersarethesamewithadifference,whichisjudgednottobespecificoraboriginal;andyetothersshowsomewhatgreaterdifferences,suchasarescientificallyexpressedbycallingthemmarkedvarieties, orelsedoubtfulspecies; whileothers, differingalittlemore, areconfidentlytermeddistinct, , isnotallthisaquestionofdegree, ofmeregradationofdifference?Andisitatalllikelythattheseseveralgradationscametobeestablishedintwototallydifferentways—someofthem (thoughnaturalistscantagreewhich) throughnaturalvariation, orothersecondarycause, andsomebyoriginalcreation, withoutsecondarycause? WehaveseenthatthejudiciousPictetanswerssuchquestionsasDarwinwouldhavehimdo, inaffirmingthat, inallprobability, thenearly-relatedspeciesoftwosuccessivefaunasweremateriallyconnected, andthatcontemporaneousspecies, similarlyresemblingeachother, werenotallcreatedso, (usingthetermasallnaturalistsdo, andmustcontinuetoemploytheword) haveonlyarelative, notanabsolutefixity;thatdifferencesfullyequivalenttowhatareheldtobespecificmayariseinthecourseoftime, sothatonespeciesmayatlengthbenaturallyreplacedbyanotherspeciesagooddeallikeit, ormaybediversifiedintotwo, three, ormorespecies, , , moreorlesstenable, forinferringmore.
