The permanent school fund is the fund described in Article VII, sections 7 and 8, of the Constitution of Nebraska, the principal of which shall be held and invested in perpetuity by the state in trust for the support of its common schools. The annual interest and other income, but not the principal, is subject to use for the support and maintenance of the common schools in each public school district of the state as the Legislature provides in accordance with Article VII, § 9, of the Constitution of Nebraska.