99. A summary court martial may try any offence punishable under any of the provisions of this Act: Provided that when there is no grave reason for immediate action and reference can without detriment to discipline be made to the officer empowered to convene a district court martial, or on active service a field general court martial, for the trial of the alleged offender, an officer holding a summary court martial shall not try without such reference any of the following offences, namely:-(a) any offence punishable under sections 24, 31 and 59;or(b) any offence against the officer holding the court.