The motion for a new trial shall be in writing and must set forth in detail and with particularity, in separate numbered paragraphs, the specific grounds or causes therefor. Such motion shall be filed before judgment and within four days after the return of the verdict; provided, on application of defendant, the court may extend the time for filing such motion for a period of thirty days; provided further, the court shall have no power to make another or further extension of the time for filing said motion.