The bonds may be in the form of negotiable coupon bonds, payable to bearer, with the privilege to the holder of having them registered as to principal on registry books kept for the college by the State Treasurer, and the principal thus made payable to the registered holder, unless the last registered transfer shall have been to bearer, upon such conditions as the board shall prescribe, or the bonds may be issued as fully registered bonds in such form as may be prescribed by the board. If issued as fully registered bonds, it may be provided that they may thereafter be converted into negotiable coupon bonds of the tenor first above described.