Section 4. There shall be established within the department such bureaus as the director shall from time to time deem necessary. All such bureaus shall be under the direction, control and supervision of the director, who may abolish or merge any such bureaus as he may deem advisable. The director shall prepare and maintain on a current basis a general statement of the organization of the department, of the assignment of functions to its various administrative units, officers and employees, and of the established places at which and the methods whereby the public may receive information or make requests. Such statement shall be known as the department’s description of organization. A current copy of the description of organization shall be on file in the offices of the state secretary and in the executive office for administration and finance. Each bureau, subject to appropriation, shall be under the charge of a bureau chief, who shall be a person of skill and experience in the field of his appointment. The position of bureau chief shall not be subject to the provisions of section nine A of chapter thirty or chapter thirty-one, and persons shall be appointed to and may be removed from such position by the director.