A rule nisi for a new trial may be amended by adding new grounds not taken at the time the motion was filed.
(Orig. Code 1863, § 3432; Code 1868, § 3452; Code 1873, § 3503; Code 1882, § 3503; Civil Code 1895, § 5121; Civil Code 1910, § 5705; Code 1933, § 70-309.)