Section 47. No officer or enlisted person of the armed forces of the commonwealth, not on leave of absence, shall be excused from duty when ordered out under section thirty-eight, forty, forty-one or forty-two, except upon a physician’s certificate of disability. If an officer or enlisted person is absent without leave and does not produce such certificate to his commanding officer, he may be tried by court-martial for desertion or absence without leave. Sickness shall not be an excuse unless he procures a certificate or satisfies the court-martial that he was unable to procure the same.