Every collection made under the authority of the act and of this part
                        shall be preserved in the public museum designated in the permit
                        and shall be accessible to the public. No such collection shall be
                        removed from such public museum without the written authority of the
                        Secretary of the Smithsonian Institution, and then only to another
                        public museum, where it shall be accessible to the public; and when any
                        public museum, which is a depository of any collection made under the
                        provisions of the act and this part, shall cease to exist, every such
                        collection in such public museum shall thereupon revert to the national
                        collections and be placed in the proper national depository.