A borrowing member for each share or fractional part thereof borrowed upon, in addition to the dues on his shares, in case such member is a shareholder borrowing on the sinking fund plan, shall pay monthly interest on his loan at such rate not exceeding 6 percent per annum as the directors shall name, until the shares borrowed upon reach the matured value of $200, $300 or $400 each, or the loan is repaid. When such matured value is reached, the share shall cancel the loan upon it and the proper surrenders and acquittances be made. A borrowing member, in case such member is not a shareholder but is borrowing on the direct reduction plan, shall pay monthly interest on the balance of principal outstanding on his loan at such rate, not exceeding 6 percent per annum, as the directors shall name, until the loan is repaid. When the loan is repaid, the proper surrenders and acquittances shall be made.