In case any member of the district board is absent at the time of any regular monthly meeting of said board, and a quorum of said board cannot be obtained by reason of the absence of said member, it shall be the duty of the chair of the board of county commissioners of the county in which the office of the district board is located to act in place of said absent member, and the acts of the district board at said meeting shall be valid so far as a quorum is concerned and shall have the same effect as though said absent member were present and acting thereat.