jus accrescendi praefertur ultima; voluntati

/jas aekrasenday prafartar altamiy volanteytay/ The right of survivorship is preferred to the last will. A devise of one's share of a joint estate, by will, is no severance of the jointure; for no testament takes effect till after the death of the testator, and by such death the right of the survivor (which accrued at the original creation of the estate, and has therefore a priority to the other) is already vested. 2 Bl.Comm. 186