Subject to the executive direction and control which is vested in the governor as chief magistrate of the state by the constitution and this Chapter, the director shall have the management of the department and, subject to the provisions of this Chapter, shall exercise all the functions of the department himself or through the department organization provided, in carrying out the provisions of law with respect to its functions, except those functions which are specifically assigned to the board of the department under the provisions of this Chapter.  Any act performed by any employee of the department under the authority of the director shall be deemed an act of the department and of the director.  The director shall designate the head of some division or other employee of the department to act as head of the department in his own absence or disability or in case of a vacancy until the absence or disability is terminated or the vacancy is filled.  In default of designation by the director the governor may make the designation.