Section 5. Within each of the divisions established in section one the commissioner shall, with the approval of the secretary, from time to time establish such branches, bureaus, sections, offices and other units as shall be necessary for efficient and economical administration of the work of the department, and, if necessary for such purpose, may with the approval of the secretary, from time to time consolidate or abolish the same. He shall prepare and keep current a general statement of such organization of the department, of the assignment of functions to its various administrative units, officials and employees, and of the established places at which and methods whereby the public may secure information or make requests. Such statement shall be known as the department's ''description of organization''. He shall file with the state secretary an attested copy of such description and of each amendment thereto, and the substance of it shall be included in each annual report he shall make to the governor and the general court.