6 . ▁ ▁The ▁system ▁for ▁nomin ating ▁candidates ▁was ▁also ▁changed . ▁After ▁ 1 9 2 8 , ▁it ▁was ▁provided ▁that ▁the ▁number ▁of ▁nom ine es ▁would ▁be ▁equal ▁to ▁twice ▁the ▁number ▁of ▁seats ▁to ▁be ▁filled ▁and ▁that ▁half ▁would ▁be ▁elected ▁by ▁the ▁D á il ▁and ▁the ▁other ▁half ▁by ▁the ▁Se an ad . ▁Both ▁houses ▁used ▁the ▁single ▁transfer able ▁vote ▁for ▁this ▁purpose . ▁The ▁right ▁of ▁out going ▁sen ators ▁to ▁nomin ate ▁themselves ▁was ▁removed . ▁ ▁By - e lections ▁The ▁constitution ▁originally ▁provided ▁that ▁prem ature ▁vac an cies ▁would ▁be ▁filled ▁by ▁a ▁vote ▁of ▁the ▁Se an ad . ▁However , ▁a ▁candidate ▁elected ▁in ▁this ▁way ▁would ▁serve ▁only ▁until ▁the ▁next ▁sen atorial ▁election , ▁when ▁the ▁seat ▁would ▁come ▁up ▁for ▁election ▁along ▁with ▁the ▁others ▁scheduled ▁to ▁be ▁filled . ▁The ▁system ▁was ▁changed ▁by ▁the ▁Constitution ▁( Am end ment ▁No . ▁ 1 1 ) ▁Act , ▁passed ▁on ▁ 1 7 ▁December ▁ 1 9 2 9 , ▁so ▁that ▁vac an cies ▁were ▁filled ▁by ▁members ▁of ▁both ▁houses ▁voting ▁together . ▁ ▁Direct ▁dem ocracy ▁As ▁adopted ▁the ▁Constitution ▁of ▁the ▁Irish ▁Free ▁State ▁contained ▁a ▁number ▁of ▁prov isions ▁for ▁direct ▁dem ocracy , ▁which ▁included ▁a ▁special ▁role ▁for ▁the ▁Se an ad . ▁Most ▁important ly ▁it ▁was ▁provided ▁that ▁the ▁Se an ad ▁could , ▁if ▁three - fif th s ▁of ▁its