▁his ▁career ▁appearing ▁in ▁Off - B road way ▁produ ctions ▁in ▁the ▁mid - 1 9 4 0 s . ▁In ▁ 1 9 4 7 – 1 9 4 8 ▁he ▁was ▁a ▁member ▁of ▁the ▁ch orus ▁in ▁the ▁Broadway ▁rev ival ▁of ▁Marc ▁Bl itz stein ' s ▁The ▁C rad le ▁Will ▁Rock . ▁In ▁ 1 9 4 9 ▁he ▁became ▁a ▁member ▁of ▁the ▁New ▁York ▁City ▁Opera ▁( N Y CO ) ▁at ▁the ▁inv itation ▁of ▁Las z lo ▁Hal asz , ▁making ▁his ▁debut ▁with ▁the ▁company ▁as ▁the ▁animal ▁vendor ▁in ▁Richard ▁Stra uss ' s ▁Der ▁Ros enk aval ier . ▁In ▁ 1 9 5 3 ▁he ▁created ▁the ▁role ▁of ▁K ok h k ary ov ▁in ▁the ▁world ▁premi ere ▁of ▁Boh us lav ▁Martin ů ' s ▁The ▁Mar riage ▁with ▁the ▁N BC ▁Opera ▁Theater . ▁ ▁Pol lock ▁appeared ▁as ▁a ▁character ▁ten or ▁in ▁numerous ▁NY CO ▁produ ctions ▁up ▁through ▁ 1 9 5 6 , ▁not ably ▁creating ▁roles ▁in ▁the ▁world ▁premier es ▁of ▁David ▁Tam kin ' s ▁The ▁Dy bb uk ▁( 1 9 5 1 ) ▁and ▁A aron ▁Cop land ’ s ▁The ▁T ender ▁Land ▁( 1 9 5 4 ). ▁He ▁also ▁sang ▁with ▁the ▁company ▁in ▁the ▁United ▁States ▁premier es ▁of ▁Gott fried ▁von ▁Ein em ' s ▁The ▁Tri al ▁( 1 9 5 3 ), ▁Frank ▁Martin ' s ▁Der ▁St