CAB/LEG/24.1 Page 12 2. In the case of a State ratifying or acceding to the Convention after the depositing of the fourth instrument of ratification or accession, the Convention shall come into force on the thirtieth day after the deposit by such State of its instrument of ratification or accession. 3. The London Convention of 1933 or any other Convention on the conservation of flora and fauna in their natural state shall cease to have effect in States in which this Convention has come into force. Article XXII Accession 1. After the date of approval specified in Article XIX paragraph (1), this Convention shall be open to accession by any independent and sovereign African State. 2. The instruments of accession shall be deposited with the Administrative Secretary General of the Organization of African Unity. Article XXIII Denunciation 1. Any Contracting State may denounce this Convention by notification in writing addressed to the Administrative Secretary General of the Organization of African Unity. 2. Such denunciation shall take effect, for such a State, one year after the date of receipt of its notification by the Administrative Secretary General of the Organization of African Unity. 3. No denunciation shall, however, be made before the expiry of a period of five years from the date at which for the State concerned this Convention comes into force. Article XXIV Revision 1. After the expiry of a period of five years from the date of entry into force of this Convention, any Contracting State may at any time make a request for the revision of part or the whole of this Convention by notification in writing addressed to the Administrative Secretary General of the Organization of African Unity.