If, before argument begins, counsel on either side applies to the court for an extension of the time prescribed for argument and states in his place or on oath, in the discretion of the court, that he cannot do the case justice within the time prescribed and that it will require for that purpose additional time, stating how much additional time will be necessary, the court shall grant such extension of time as may seem reasonable and proper, provided that the extension of time granted in misdemeanor cases or cases brought up from inferior judicatories shall not exceed 30 minutes.