Limitation of prosecutions or suits against officers.

All prosecutions of any officer or person empowered to exercise powers or to perform duties or discharge functions under this Act, and all actions which may be lawfully brought against the Government or any of the aforesaid officers or persons in respect of anything done or alleged to have been done in pursuance of this Act, shall be instituted within four months from the date of the act complained of, and not afterwards; and any such action shall be dismissed- (a) if the plaintiff does not prove that, previously to bringing such action, he has