Section thirteen in every portion of the State, which has been granted to the State, shall be preserved for the use and benefit of the University of Oklahoma and the University Preparatory School, one-third; of the normal schools now established, or hereafter to be established, one-third; and of the Agricultural and Mechanical College and Colored Agricultural and Normal University, one-third. The said lands or the proceeds thereof as above apportioned to be divided between the institutions as the Legislature may prescribe: Provided, That the said lands so reserved, or the proceeds of the sale thereof, or of any indemnity lands granted in lieu of section thirteen shall be safely kept or invested and preserved by the State as a trust, which shall never be diminished, but may be added to, and the income thereof, interest, rentals, or otherwise, only shall be used exclusively for the benefit of said educational institutions. Such educational institutions shall remain under the exclusive control of the State and no part of the proceeds arising from the sale or disposal of any lands granted for educational purposes, or the income or rentals thereof, shall be used for the support of any religious or sectarian school, college, or university, and no portion of the funds arising from the sale of sections thirteen or any indemnity lands selected in lieu thereof, either principal or interest, shall ever be diverted, either temporarily or permanently, from the purpose for which said lands were granted to the State.