The board shall have the power to create within the board such divisions as may be necessary for its effective administration. Each division in the board shall be headed by and be under the direction, supervision and control of an officer who shall be designated as the chief of such division. All chiefs of divisions shall be appointed by the board. Before entering upon the discharge of their duties, such chiefs of divisions shall take the constitutional oath of office. The salaries of such chiefs of divisions shall be fixed by the board, with the approval of the Governor, and shall be paid in the same manner and at the same time as the salaries of other state officers, but no one of such salaries shall exceed such amount as is provided by statute; except, that the salaries paid two physicians may not be in excess of such amount as is provided by statute. Each such officer shall devote his full time to his official duties and shall hold no other lucrative position while serving as such.