▁Na arden , ▁but ▁returned ▁to ▁En k hu izen ▁two ▁years ▁later ▁to ▁a ▁school ▁run ▁by ▁Wille m ▁van ▁Nie uw en hu izen . ▁In ▁ 1 6 2 5 ▁he ▁en rolled ▁at ▁the ▁University ▁of ▁Le iden ▁and ▁completed ▁initial ▁studies ▁in ▁natural ▁history ▁and ▁philosophy ▁under ▁Gilbert ▁J ach ae us ▁( 1 5 7 8 – 1 6 2 8 ) ▁and ▁Franco ▁Pet ri ▁Burg ers d ijk ▁. ▁ ▁He ▁then ▁turned ▁to ▁medical ▁studies , ▁att ending ▁lect ures ▁by ▁Otto ▁He urn ius , ▁E wald us ▁Sch re vel ius , ▁Ad rian ▁van ▁Fal ken burg ▁( 1 5 8 1 – 1 6 5 0 ) ▁and ▁Ad olph us ▁Vor st ius . ▁He ▁continued ▁his ▁studies ▁under ▁Men el aus ▁W ins em ius ▁( 1 5 9 1 – 1 6 3 9 ), ▁and ▁completed ▁his ▁doctor ate ▁on ▁ 1 9 ▁October ▁ 1 6 3 0 ▁with ▁a ▁treat ise ▁on ▁De ▁vir ul ent ia ▁ven erea . ▁In ▁ 1 6 3 1 ▁he ▁went ▁to ▁Amsterdam , ▁where ▁he ▁worked ▁in ▁medicine ▁with ▁his ▁father . ▁Here ▁he ▁was ▁able ▁to ▁continue ▁his ▁studies ▁using ▁his ▁father ' s ▁extensive ▁library , ▁and ▁became ▁a ▁good ▁friend ▁of ▁Nicola es ▁T ulp . ▁ ▁He ▁married ▁Hel ena ▁Gr ond t ▁in ▁ 1 6 3 4 ▁in ▁Amsterdam ; ▁they ▁subsequently ▁had ▁five ▁daughters ▁and ▁two ▁sons . ▁