The county commission in each county shall administer the county school fund of the county. In each county wherein the annual distribution of the liquidated capital of the county school fund has not been ordered by the voters pursuant to sections 166.151 to 166.161, the proceeds of the fund shall be invested by the county commission in registered bonds of the United States, or in bonds of the state or in approved bonds of any city or school district thereof, or in bonds or other securities the payment of which is fully guaranteed by the United States government and shall be preserved as a county school fund. Annually, on or before September thirtieth, in each county of the state all interest accruing from the investment of the capital of the county school fund, if any, the clear proceeds of all penalties and fines collected for any breach of the penal laws of the state, the net proceeds from the sale of estrays, and all other money lawfully coming into the fund, shall be collected and distributed to the school districts of the county by the county clerk in the same proportion that the September membership of a school district, determined as provided in (1) of subdivision (8) of section 163.011 bears to the sum of the September membership of all the districts in the county. He shall immediately after making the apportionments enter them in a book to be kept for that purpose, and shall furnish each district clerk a copy of the apportionment. The county treasurer shall pay over to the treasurer of the school board of every district in the county the amount due each respective district. The clear proceeds of all forfeitures collected for any breach of the penal laws of the state distributed for education shall be transferred to the school building revolving fund.