The controller in counties of the third to eighth classes shall draw and certify vouchers for all bills, claims and demands presented to him, which he approves and only for such as he approves, and shall forward the vouchers together with checks therefor with the bills, claims or demands to the county commissioners for their approval. If the county commissioners approve a voucher, at least two commissioners shall sign the check as properly drawn upon the county treasury. In such cases facsimiles of their signatures may be used. Thereupon the bill, claim or demand, and the voucher thereof, shall be returned to the controller for filing in his office and the check shall be forwarded to the county treasurer. The county treasurer shall sign the check as his draft upon the funds of the institution district in the county treasury, but the treasurer shall not sign any check not already signed, as herein provided, by the commissioners and the controller. Vouchers shall be numbered serially before the controller forwards them to the county commissioners and every check incident thereto shall bear the same serial number as the voucher as well as the number or numbers which may be put upon it or them by the county treasurer. If the county commissioners refuse to approve any bill, claim or demand, they shall return the same together with the voucher and check involved to the controller for filing in his office. In counties not having a controller, the county commissioners shall approve each transaction and the voucher and check shall be drawn by their chief clerk who shall keep files of the bills, claims or demands involved and of the vouchers. At least two commissioners shall sign the checks either personally or by facsimile, and they shall be forwarded, as hereinbefore provided, to the county treasurer for his signature. In all cases the cancelled checks shall be filed in the office of the county treasurer, but he shall transmit, at such times as the controller shall establish, a list of all checks paid from the funds of the institution district in the county treasury and not previously transmitted, giving their voucher serial numbers.