Upon failure or refusal of the police jury of any parish to organize a hospital service district, they are hereby required to and shall form such district when petitioned to so do upon petition presented to the police jury, signed by not less than twenty-five persons owning or assessed for lands in said districts.  In presenting such petition to the police jury, such petition shall set forth substantially the boundaries of the district which is proposed to be organized.  

Acts 1950, No. 420, §9.