All bonds shall bear the facsimile signature of the Governor, the facsimile signature of the Controller, and the facsimile signature of the Treasurer, and each of the bonds shall bear an impress or a facsimile of the Great Seal of the State of California. Each such signature shall be that of the person who shall be in office at the date of authorizing the affixing thereof. Bonds and coupons so executed, when sold, shall be valid and binding notwithstanding any of these persons having ceased to hold their respective offices before the issuance and delivery of the bonds.