The act of growing to a thing; usually applied to the gradual and imperceptible, accumulation of land by natural causes, as out of the sea or a river. Accretion of land is of two kinds: By alluvion, i.e., by the washing up of sand or soil, so as to form firm ground; or by dereliction, as when the sea shrinks below the usual water mark. The increase of real estate by the addition of portions of soil, by gradual deposition through the operation of natural causes, to that already in possession of the owner. 2 Washb. Real Prop. 451. Jefferis v. East Omaha Land Co., 134 U. S. 178, 10 Sup. Ct. 518, 33 L. Ed. 872; New Orleans v. United States, 10 Pet 662, 717, 9 L. Ed. 573; Lam mers v. Nissen, 4 Neb. 245; Mulry v. Norton, 100 N. Y. 424, 3N. B. 581, 53 Am. Rep. 206; Nebraska v. Iowa, 143 U. S. 359, 12 Sup. Ct. 396, 36 L. Ed. 186; Ewing v. Burnet, 11 Pet. 41, 9 L. Ed. 624; St. Louis, etc., R. Co. v. Ramsey, 53 Ark. 314, 13 S. W. 931, 8 L. R. A. 559, 22 Am. St. Rep. 195. In the civil law. The right of heirs or legatees to unite or aggregate with their shares or portions of the estate the portion of any co heir or legatee who refuses to accept it, fails to comply with a condition, becomes incapacitated to inherit, or dies before the testator. In this case, his portion is said to be “vacant,” and is added to the corpus of the estate and divided with it, the several shares or portions of the other heirs or legatees being thus increased by “accretion.” Bmeric v. Alvarado, 64 Cal, 529, 2 Pac. 418; Succession of Hunter, 45 La. Ann. 262, 12 South. 312.