Section 39C. County notes, when issued for a serial loan, may be made payable to ”bearer”, and when so issued section thirty-nine B may be construed by the director as being properly complied with in so far as it relates to the proper filling in of the space provided for the name of the purchaser of the loan, and he may certify such notes; provided, that before certification there shall be filed with him by the county treasurer the name of the purchaser of such loan.