The degree of authority, control, or administration to be exercised by the Mandatory shall, if not previously agreed upon by the Members of the League, be explicitly defined in each case by the Council. A permanent Commission shall be constituted to receive and examine the annual reports of the Mandatories and to advise the Council on all matters relating to the observance of the mandates. ARTICLE 23. Subject to and in accordance with the provisions of international conventions existing or hereafter to be agreed upon, the Members of the League: (_a_) will endeavour to secure and maintain fair and humane conditions of labour for men, women, and children, both in their own countries and in all countries to which their commercial and industrial relations extend, and for that purpose will establish and maintain the necessary international organisations; (_b_) undertake to secure just treatment of the native inhabitants of territories under their control; (_c_) will entrust the League with the general supervision over the execution of agreements with regard to the traffic in women and children, and the traffic in opium and other dangerous drugs; (_d_) will entrust the League with the general supervision of the trade in arms and ammunition with the countries in which the control of this traffic is necessary in the common interest; (_e_) will make provision to secure and maintain freedom of communications and of transit and equitable treatment for the commerce of all Members of the League. In this connection, the special necessities of the regions devastated during the war of 1914-1918 shall be borne in mind; (_f_) will endeavour to take steps in matters of international concern for the prevention and control of disease. {130} ARTICLE 24. There shall be placed under the direction of the League all international bureaux already established by general treaties if the parties to such treaties consent. All such international bureaux and all commissions for the regulation of matters of international interest hereafter constituted shall be placed under the direction of the League. In all matters of international interest which are regulated by general convention but which are not placed under the control of international bureaux or commissions, the Secretariat of the League shall, subject to the consent of the Council and if desired by the parties, collect and distribute all relevant information and shall render any other assistance which may be necessary or desirable. The Council may include as part of the expenses of the Secretariat the expenses of any bureau or commission which is placed under the direction of the League. ARTICLE 25.