Section 154(2A) in The Representation of the People Act, 1951
(2A)In order that, as nearly as may be, one-third of the members may retire on the second day of April, 1958, and on the expiration of every second year thereafter, the President shall, as soon as may be after the commencement of the Constitution (Seventh Amendment) Act, 1956 after consultation with the Election Commission, make by order such provisions as he thinks fit in regard to the terms of office of the members elected under sub-section (2) of section 147.
