No shareholder in any such association shall own shares of a greater aggregate par value than twenty percent (20%) of the paid-in capital stock, except as hereinafter provided, or be entitled to more than one vote. A mutual association shall reserve the right of purchasing the stock of any member whose stock is for sale, and may restrict the transfer of stock to such persons as are made eligible to membership in the bylaws. (1915, c. 144, s. 9; C.S., s. 5251; 1925, c. 179, s. 1.)