Iowa Code § 498.31: Chapter extended to former associations.

All corporations, or associations heretofore organized and doing business under prior statutes, or which have attempted so to organize and do business cooperatively, shall have the benefit of all the provisions of this chapter and be bound thereby, on filing with the secretary of state amended and substituted articles of incorporation drawn in accordance with the provisions of this chapter and a written declaration signed and sworn to by the president and secretary, to the effect that said company or association has, by a majority vote of its stockholders, decided to accept the benefits of and to be bound by the provisions of this chapter.