Section 11. At the end of each calendar year, after the bills for the extinguishment of forest fires shall have been presented for that year, the Auditor General of the Commonwealth shall prepare a statement showing the expenditure made for the extinguishment of fires in each of the counties of the State, and shall transmit to the Commissioners of each county a copy of the statement relating to their respective county. The Auditor General shall, at the same time, state an account with each of the said counties, and collect from each county an amount equal to one-fifth of the amount expended by the Commonwealth for the extinguishment of forest fires in that particular county. The county commissioners of each county shall, immediately upon receipt of the stated account of the Auditor General, forward to him, for the use of the Commonwealth, the amount of money so found to be due and owing by the county for the extinguishment of forest fires. In case the said account is not settled within thirty days after its receipt by the county commissioners, the Auditor General is hereby authorized, empowered, and required to collect the amount of the then delinquent account stated, in manner provided by existing law for the collection of accounts due the Commonwealth.