All such bonds shall be signed by the President and any two members of the Board of Trustees and shall have the seal of the University affixed thereto (or a facsimile of the signature of the President of the Board of Trustees or of said seal or both thereof, may be imprinted, engraved or otherwise reproduced thereon), and shall be attested by the Secretary of such Board of Trustees, and in case any officer who shall have signed or attested any such bonds, or whose facsimile appears on the bonds or interest coupons shall cease to be such officer, before such bonds shall have been issued by the Board of Trustees, such bonds may nevertheless be validly issued by said Board. Said Board of Trustees may provide for registration as to principal only or as to both principal and interest of any such bonds. All interest coupons shall be authenticated by the facsimile signatures of the President and Secretary of The Board of Trustees of the University of Illinois. Such bonds shall be payable only from the revenues of any such building, buildings, facility or facilities or any combination thereof, and, when authorized by the Board of Trustees, from University income authorized by law to be retained in the treasury of the University, and applied as a supplement to such revenues, and shall in no case be or become a charge or debt against the State of Illinois or The Board of Trustees of the University of Illinois, and such fact shall be plainly stated on the face of each bond.