. . . . "Rule 25(d), Rules of Civil Procedure, 28 U.S.C.A. now provides: 'When an officer of the United States, or of the District of Columbia, the Canal Zone, a territory, an insular possession, a state, county, city, or other governmental agency, is a party to an action and during its pendency dies, resigns, or otherwise ceases to hold office, the action may be continued and maintained by or against his" . .