21. The provisions of sections 4A, 4B, 10, 13, 24B, 29, 36 to 44C (inclusive), 45 to 48 (inclusive), 49E, 49F, 50, 54, 61 to 63 (inclusive), 65 to 67A (inclusive) of the Income tax Act, 1922, shall apply with such modifications, if any, as may be prescribed as if the said provisions were provisions of this Act and referred to excess profits tax instead of to income tax, and every officer exercising powers under the said provisions in regard to income tax may exercise the like powers under this Act in regard to excess profits tax in respect of cases assigned to him under sub section (3) of section 3 as he exercises in relation to income tax under the said Act: Provided that references in the said provisions to the assessee shall be construed as references to a person to whose business this Act applies.