(d) the first Academic Council and the first Planning Board, shall be constituted on the expiry of a period of ten years from the commencement of this Act and during the said period of ten years, the powers and functions of. these two authorities shall be exercised and performed by the Planning and Academic Committee constituted under section 20: Provided that if any vacancy occurs in the above offices or authorities, the same shall be filled by appointment or nomination, as the case may be, by the Visitor, and the persons so appointed or nominated shall hold office for so long as the officer or member in whose place he is appointed or nominated would have held that office, if such vacancy had not occurred.