Sales of lands for delinquent assessments may be made either under the law which was in force at the time of the creation of the drainage district, or under that in force at the time of sale, as may be deemed by the county treasurer more effectual for the enforcement of the assessments and the protection of the interest of the holders of bonds predicated thereon. Any sales of lands heretofore made under either of such laws are declared valid and effectual.
1927, p. 16; Michie Code 1942, § 1771a.