Two or more future interests may be created to take effect in the alternative, so that, if the first in order fails to vest, the next in succession shall be substituted for it, and take effect accordingly.

Source: CivC 1877, § 188; CL 1887, § 2704; RCivC 1903, § 211; RC 1919, § 281; SDC 1939, § 51.0218.