A yielding up of an es-tate tor life or years to hlm who has an immediate estate in reversion or remainder, by which the lesser estate ls merged in the greater by mutual agreement. Co. Lltt. 337b. And see Coe v. Hobby, 72 N. Y. 145, 28 Am. Rep. 120; Gluck v. Baltlmore, 81 Md. 315