Each justice court juror shall be entitled to receive $6.00 for each day’s attendance, and $3.00 for each half day’s attendance upon any term of justice court, to be paid out of the city treasury of the city on the certificate or order of the clerk of the justice court: Provided, There shall be deducted therefrom the amount of any certificate issued to such juror on account of services performed as a juror in a case brought for a violation of the criminal laws of the state. The constable, or deputy sheriff, summoning said jurors, shall be entitled to receive the sum of 50 cents for each summons so served, and the constable shall be entitled to $4.00 per day for each day’s attendance and $2.00 for each half day’s attendance upon the jury at any such jury term, to be paid out of the city treasury on the certificate or order of the clerk of the justice court. Any city may by ordinance increase the compensation of jurors and constables to a sum not exceeding $6.00 for each day’s attendance and $3.00 for each half day’s attendance.