The endowment fund authorized by section 2, Laws of Missouri 1925, page 136, shall be maintained by the department of natural resources as a permanent endowment for the maintenance of the Confederate Memorial Park. The department of natural resources may accept gifts, donations, or bequests for the maintenance of the memorial park and for the endowment fund until the fund reaches the sum of seventy-five thousand dollars. The department of natural resources may sell, convey or otherwise convert into money any property received and shall invest all moneys of the endowment fund and use the income therefrom for the maintenance of the park, but the principal shall remain intact as a permanent endowment fund.