One who contracts a field [as a sharecropper] from a Jew, an idolater, or a Cuthean di-vides [the produce] in their presence. One who leases a field [as a tenant-farmer] from a Jew separates terumah and [then] gives him [his share]. R’ Yehudah said: When [is this so]? When he gave him from that [same] field and from that [same] species; but if he gave him from a different field or from a different species, he tithes and [then] gives him.