Section 26. The term of office of a major general of the line shall be five years. The term of office of a brigadier general of the line shall be six years. The term of office of a colonel, commanding an organization, except an air medical group or any army medical battalion, shall be seven years. The terms of office aforesaid shall commence from the date of appointment. Officers so appointed shall be ineligible for reappointment in the same office. The time during which an officer is in the military service of the United States under section one hundred and eleven of the National Defense Act shall be excluded from the term herein specified.