The Commission is authorized to designate any officer or employee of any other department of the Government on duty in any Territory or possession of the United States to render therein such service in connection with the administration of this chapter as the Commission may prescribe and also to designate any officer or employee of any other department of the Government to render such services at any place within the United States in connection with the administration of this subchapter as may be necessary: , That such designation shall be approved by the head of the department in which such person is employed.Provided