A city may take, by gift, grant, devise or bequest, any money or property, real, personal or mixed, in trust for the benefit of the pension fund. The care, management, investment and disposal of the body of the trust shall be vested in the officer or officers of the city as the city may designate. The care, management and disposal shall be directed by ordinance and the body of the trust shall be governed by the ordinance, subject to directions not inconsistent with the ordinance, as the settlor of the trust may prescribe.