Assessments against lands in any general improvement or divisional district authorized under this chapter, when collected by the county treasurer shall constitute a special fund or funds as the case may be, to be called respectively, the "bond fund of general improvement or divisional district No. . . . .", the "contract fund of general improvement or divisional district No. . . . .", the "warrant fund of general improvement or divisional district No. . . . .", and any other special fund authorized by law.