Section 31. The by-laws of the retirement association, and any amendments thereto, shall be submitted to the commissioner and shall prescribe the manner in which, and the officers and agents by whom, the retirement association may be conducted and the manner in which its funds may be invested and paid out. Such retirement association shall be formed when its by-laws have been approved and agreed to by a majority of the trustees of each of 15 or more cooperative banks and have been approved by the commissioner. The association shall annually, on or before August 1 report to the commissioner such statements of its membership and financial transactions for the year ending on the preceding December 31st as the commissioner may consider necessary to show its business and standing. The commissioner may verify such statement by an examination of the books and papers of the retirement association. The retirement association shall not be subject to chapter 32 or chapter 175 or other laws as relate to insurance companies or other retirement associations.