§ 73. Oath of office. Every commissioned officer shall take and subscribe the oath of office prescribed for officers of the organized militia by the applicable laws of the United States and regulations issued pursuant to this chapter. Such oath shall be taken and subscribed before a commissioned or warrant officer of the organized militia or of any branch of the armed forces of the United States, or before a notary public or other officer authorized by the laws of this state to take and certify the acknowledgment and proof of conveyances of real property to entitle them to be recorded.