The term of office of the member shall be four years and until the appointment and qualification of his successor; provided that the first members of the board shall classify themselves by lot within the city and county group and the citizen-at-large group so that approximately one-third (1/3) of the members of each group shall hold office for two (2) years, approximately one-third (1/3) shall hold office for three (3) years and approximately one-third (1/3) shall hold office for four (4) years. The power which originally appointed a member whose term has expired shall appoint his successor for a full term of four (4) years. Any member may be removed by the power appointing him.