▁the ▁mechan isms ▁of ▁ple iot ropy . ▁In ▁ 1 9 3 8 ▁Gr une berg ▁published ▁an ▁article ▁div iding ▁ple iot ropy ▁into ▁two ▁distinct ▁types : ▁" gen u ine " ▁and ▁" sp ur ious " ▁ple iot ropy . ▁" G enu ine " ▁ple iot ropy ▁is ▁when ▁two ▁distinct ▁primary ▁products ▁arise ▁from ▁one ▁loc us . ▁" Sp ur ious " ▁ple iot ropy , ▁on ▁the ▁other ▁hand , ▁is ▁either ▁when ▁one ▁primary ▁product ▁is ▁util ized ▁in ▁different ▁ways ▁or ▁when ▁one ▁primary ▁product ▁initi ates ▁a ▁cas cade ▁of ▁events ▁with ▁different ▁phen ot yp ic ▁consequences . ▁Gr une berg ▁came ▁to ▁these ▁dist in ctions ▁after ▁experiment ing ▁on ▁r ats ▁with ▁ske let al ▁mut ations . ▁He ▁recognized ▁that ▁" sp ur ious " ▁ple iot ropy ▁was ▁present ▁in ▁the ▁mut ation , ▁while ▁" gen u ine " ▁ple iot ropy ▁was ▁not , ▁thus ▁partially ▁invalid ating ▁his ▁own ▁original ▁theory . ▁Through ▁subsequent ▁research , ▁it ▁has ▁been ▁established ▁that ▁Gr une berg ' s ▁definition ▁of ▁" sp ur ious " ▁ple iot ropy ▁is ▁what ▁we ▁now ▁identify ▁simply ▁as ▁" ple iot ropy ". ▁ ▁In ▁ 1 9 4 1 ▁American ▁gen etic ists ▁George ▁B ead le ▁and ▁Edward ▁T atum ▁further ▁invalid ated ▁Gr une berg ' s ▁definition ▁of ▁" gen u ine " ▁ple iot ropy , ▁advoc ating ▁instead ▁for ▁the ▁" one