In any of the several counties of the commonwealth, wherein, by existing laws, the county treasurer is authorized and required to collect state and county taxes during a certain period, after which all unpaid or delinquent taxes are collected by collectors appointed under existing laws, it shall be the duty of the county treasurer on and after the first day of October in each year, in any election district, where such collector of unpaid or delinquent taxes may not have been appointed, to receive such unpaid or delinquent taxes until a collector be appointed and qualified as provided for under existing laws: Provided, That no percentage shall be charged and allowed the treasurer for collecting such taxes.